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  • richardmitnick 5:33 pm on May 1, 2017 Permalink | Reply
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    From Physics Today: “An electron–proton collider could bridge the gap between the LHC and its successor” 

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    Physics Today

    May 1, 2017
    Toni Feder

    Whether the CERN facility goes ahead will depend on community support for it in the next European strategy for particle physics.

    Physics Today 70, 5, 29 (2017); doi: http://dx.doi.org/10.1063/PT.3.3551

    Last year the CERN council gave the green light to increasing by an order of magnitude the luminosity of the Large Hadron Collider. The beefed-up LHC is expected to start up around 2025 and run for about a decade. Beyond that, the jury is out on what future machines CERN—and the global particle-physics community—should pursue.

    Max Klein of the University of Liverpool thinks he has the perfect “Goldilocks” experiment that could bridge the discovery gap between the LHC and its successor: an electron–proton collider.

    Dubbed the LHeC, the new machine would require the construction of an electron accelerator that would shoot electrons at protons and ions produced by the LHC. And whereas next-generation colliders are projected to cost tens of billions of dollars, the LHeC would have a price tag of a half a billion to a billion dollars.

    The funds could be scraped together from CERN’s regular budget. It’s not peanuts, but it’s not a multibillion dollar machine. “It’s in between,” says Klein. “It’s too big to just smuggle in. It’s a serious decision.”

    No one can say the physics case for the LHeC is not good, says Achille Stocchi, director of the Linear Accelerator Laboratory in Orsay, France. “But people can have different priorities.” He notes that among potential partners, momentum is growing for his lab to build an experiment that would be a test bed for LHeC technology and a user facility for particle, nuclear, and applied physics; a decision is likely by the end of this year.

    Deep inelastic scattering

    Scattering electrons off protons probes hadronic substructure (see the story on page 14 of this issue).

    For example, HERA, the only previous electron–proton collider, which ran from 1992 to 2007 at DESY, the German Electron Synchrotron in Hamburg, opened a window into the distribution of gluons inside protons.

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    HERA was the largest particle accelerator at DESY and Germany’s largest research instrument.

    Without the HERA data, “we wouldn’t have been able to quantitatively interpret the Higgs boson,” says Klein. “The LHeC will measure the gluon distribution in protons much more precisely. Quantum chromodynamics can be improved dramatically.” The LHeC would smash electrons and protons together at four times the center-of-mass energy and 1000 times the luminosity of HERA.

    In electron–proton collisions, explains Klein, the W and Z bosons emit Higgs bosons. And with the high-luminosity LHC, there will be enough collisions for scientists to measure the subsequent decay of the Higgs into charm and bottom quarks with great precision. That capability is crucial, he says, for exploring the Higgs “as a portal to new physics, such as dark matter, exotic scalar bosons, and anomalous Higgs–top quark couplings.”

    The LHeC could make significant contributions in several other areas too. The observation of a predicted nonlinear interaction would change our understanding of the evolution of gluons and quarks and of proton structure, says Klein. The LHeC may find instantons, topological solutions of the Lagrangian in quantum chromodynamics. And electron–proton collisions could determine if sterile neutrinos exist (see Physics Today, October 2016, page 15). Another “huge terra incognita,” he says, is electron–ion physics.

    Exploiting the LHC

    Although the LHeC concept has been around for some years, so far it “is not so popular,” says Herwig Schopper, former CERN director general, chair of the lab’s international advisory committee on the LHeC, and a fan of the proposal. “Many would say electron–proton [physics] is not interesting. They are fixated on weak interactions in the standard model.” He notes that “high-energy physics is in a strange situation.” Theory does not indicate which way to go, he says. Studying electron–proton collisions would be “special. It doesn’t exist anywhere else,” and it would “exploit the LHC as much as possible—the big investments in terms of money and human effort.”

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    In its current design, the LHeC detector is 12 m in the beam direction and about 9 m in diameter. The schematic shows a simulated electron–proton scattering event that produces a Higgs particle that subsequently decays into a pair of bottom quarks. The green is the electromagnetic calorimeter, which is surrounded by the solenoidal magnet; shown in yellow are the hadron calorimeters; the red circles are the wheels on which silicon detectors that track particle signals are mounted; and the gray on the outside is the muon detector.

    PETER KOSTKA (UNIVERSITY OF LIVERPOOL)

    Whatever its science reach, the LHeC would be far cheaper than the bigger colliders being contemplated by the international particle-physics community—namely, the International Linear Collider (ILC) electron–positron machine in Japan; a large circular collider in China, with electron–positron, proton–proton, and electron–proton options; and, under study at CERN, the compact linear collider (CLIC) for electrons and positrons or the Future Circular Collider (FCC), which incorporates all three collision scenarios (see Physics Today, July 2014, page 23, and March 2013, page 23). A next-generation machine may happen, but it will take a long time, says Schopper. Oliver Brüning, deputy project leader for the LHC high-luminosity upgrade and co-leader with Klein of the LHeC project, says, “Management likes the [LHeC] idea as a possibility, but they are shy to say, ‘Do it.’ ”

    As envisioned in a 2012 conceptual design study, the LHeC would have a racetrack-shaped electron accelerator housed in its own 9 km tunnel and would kiss the LHC tunnel at one spot, where the detector would be located. The accelerator’s straight sides would each include 1-km-long linacs. The electrons would circulate three times, gaining 10 GeV in each linac pass, for a total of 60 GeV when they are released at the collision site. After the beam passes through the interaction site, its energy would be recovered by introducing a phase change and decelerating the beam and would be stored for use in the next acceleration cycle.

    The approach is called energy recovery, and the idea is to use minimal power and reduce energy losses. For the LHeC, using an energy recovery linear (ERL) accelerator makes it possible to reach higher luminosity than limits on how much power CERN can draw from the grid would otherwise permit.

    The ERL approach has been realized with a single pass. But for the LHeC the technology needs to be tested at higher currents and with the beam making multiple passes. That’s the goal of a proposed test bed at Orsay—PERLE (Powerful ERL for Experiments). Klein notes that the LHeC would work as an add-on to the LHC, a higher-energy LHC, or the FCC. And the ERL approach would be “a long-term investment for CERN’s hadron collider program.”

    According to Stocchi, who is spearheading the PERLE proposal, the facility could accelerate electrons up to 500 MeV by having them zip around the loop at least three times. Simulations show that the energy could be scaled up to the LHeC, he says. The PERLE facility would be an international collaboration; partners so far include CERN, the Thomas Jefferson National Accelerator Facility in the US, the Budker Institute of Nuclear Physics in Russia, and Daresbury Laboratory and Liverpool University in the UK. The PERLE project has not been completely costed, but building it from scratch would come to around €20 million ($21.5 million), Stocchi says. If partners provide magnets, cryomodules, and other components, that would bring down the tab and provide R&D for future facilities; some in-kind commitments have been made already. If PERLE gets approval and funding, it could be ready by about 2021.

    For Stocchi, a key selling point for PERLE is that it would serve not only as a prototype for the LHeC, but also as a user facility with a high flux of electrons and photons; the photons are to be produced by backscattering laser light off the electron beam. The electrons would be used for experiments in nuclear and particle physics, and the photons would be used for medical sciences, nanoscience, nuclear physics, materials science, and more. Successful technology demonstration at PERLE is not a guarantee that the LHeC will go ahead, Stocchi says. But PERLE is worthwhile on its own, he argues, and “if you don’t do PERLE, you won’t do the LHeC.”

    If the LHeC does happen, the most suitable site for the electron–proton collisions is where the ALICE heavy-ion experiment’s detector is located, Klein notes. The other potential LHC interaction regions are ruled out because they are reserved for ongoing experiments or because of civil engineering constraints. The ALICE experiment is planned to run at the LHC through 2029. That timing works for the LHeC; it would give the multiturn ERL technology, a precision electron–hadron detector, civil engineering, and other preparations time to get ready. The detector would be installed during LHC down time. “We would not interrupt the LHC,” says Klein, who stresses that LHeC’s electron–proton collisions could run simultaneously with the LHC’s proton–proton collisions.

    Collision decisions

    Another experiment under study at CERN that could be done on a shorter time scale and lower budget than CLIC or the FCC is an energy upgrade to the LHC. Switching out the superconducting niobium-titanium electromagnets for stronger bending electromagnets made of niobium-tin would nearly double the collision energy. Beyond the potential for discovery that higher collision energies might bring, the switch would be a technology demonstrator for a future FCC.

    So far, experiments have been made with roughly 1% of the LHC’s integrated luminosity. The accepted approach among particle physicists is to take more data before making any major decisions on future machines. And if Japan decides to go ahead with the ILC, or if CERN goes for CLIC, the “LHeC would be wiped out,” Brüning says, since CERN’s investments in those other projects would leave little wiggle room for funding.

    “I do think [the LHeC] could be a good project between the luminosity [upgrade] and the next project, but 2029 sounds too early—more like 2035 or 2040,” says Frédérick Bordry, CERN’s director for accelerators and technology. The project needs more support from the particle-physics community, he notes. “The next European strategy for particle physics will be very important for the LHeC.” The strategy recommendations are slated to come out in 2020, and decisions may be delayed beyond that.

    © 2017 American Institute of Physics.

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    The mission of Physics Today is to be a unifying influence for the diverse areas of physics and the physics-related sciences.

    It does that in three ways:

    • by providing authoritative, engaging coverage of physical science research and its applications without regard to disciplinary boundaries;
    • by providing authoritative, engaging coverage of the often complex interactions of the physical sciences with each other and with other spheres of human endeavor; and
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  • richardmitnick 3:38 pm on December 30, 2016 Permalink | Reply
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    From Physics Today: Women in STEM – “Happy birthday to particle astrophysicist Persis Drell.” 

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    Physics Today

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    Persis Drell, dean of the Stanford School of Engineering, will become provost on Feb. 1. (Image credit: Saul Bromberger and Sandra Hoover)

    She was born in Palo Alto, California, in 1955. After earning her PhD in atomic physics in 1983 from the University of California, Berkeley, Drell worked as a postdoc at Lawrence Berkeley National Laboratory and then joined the faculty of Cornell University in 1988. She left in 2002 to become director of research at SLAC. Drell was promoted to deputy director in 2005 and director in 2007. While at SLAC, Drell worked on the construction of the Fermi Gamma-Ray Space Telescope, among other projects. Not only was Drell the first female director of SLAC, but she also became the first woman to serve as dean of the Stanford School of Engineering when she accepted the position in 2014. Drell is also a cellist who enjoys playing chamber music. She is the daughter of the late physicist Sidney Drell, who was an emeritus professor at SLAC. As of 1 February 2017, Drell will take on a new position at Stanford as provost.

    From social media .

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    “Our mission

    The mission of Physics Today is to be a unifying influence for the diverse areas of physics and the physics-related sciences.

    It does that in three ways:

    • by providing authoritative, engaging coverage of physical science research and its applications without regard to disciplinary boundaries;
    • by providing authoritative, engaging coverage of the often complex interactions of the physical sciences with each other and with other spheres of human endeavor; and
    • by providing a forum for the exchange of ideas within the scientific community.”

     
  • richardmitnick 1:47 pm on December 9, 2016 Permalink | Reply
    Tags: , , Physics Today, Turmoil in Turkey hits science   

    From Physics Today: “Turmoil in Turkey hits science” 

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    Physics Today

    Toni Feder
    December 2016, page 30

    “Sometimes I am amazed that my life and that of many of my colleagues remains as undisturbed on an everyday basis as it does. But there are no guarantees that it remains unimpacted,” says Cihan Saçlıoğlu, a theoretical particle physicist at Sabancı University near Istanbul. “My university is like a haven.”

    Turkey is suffering from wars in neighboring Iraq and Syria, an influx of Syrian refugees, and attacks by Islamic State adherents and Kurdish PKK terrorists. On top of that, Turkish science faces chronic problems of low-level investment in large-scale scientific infrastructure and eroding autonomy of universities, says Ercan Alp, a physicist at Argonne National Laboratory who maintains close ties with his native Turkey.

    The 15 July failed coup, he says, “added salt to the wound.”

    The Turkish government admits that it has ousted around 100 000 state employees in the last year or so. That includes a thinning out of the police and armed forces and firings of nearly 28 000 people in K–12 education. In a series of purges, some 2500 academics have been sacked and 15 universities have been shuttered. A mood of uncertainty, suspicion, and fear pervades campuses.

    Purges

    The purges and university closures are aimed at supporters of Fethullah Gülen, a former imam who lives in self-imposed exile in Pennsylvania. Until they fell out in recent years, President Recep Tayyip Erdoğan and Gülen were close allies; Erdoğan blames Gülen for the coup. The Gülen movement is known to have penetrated deeply into Turkish education, business, government agencies, army, and police. Among government officials and secularists, the movement’s far-reaching international network of schools and universities are seen as nurseries for growing a workforce loyal to Gülen and a threat to democracy in Turkey.

    But the purges “also resulted in some unfair accusations,” says Haluk Ünal, a professor of finance at the University of Maryland and president of the Turkish American Scientists and Scholars Association (TASSA). Academics come under suspicion for voicing criticism of the current regime or for seeming to support the PKK. The clampdown on academic freedom threatens national and international collaboration and could have a negative impact on R&D, Ünal says. And the intense scrutiny “under the magnifying glass” that many scientists endure when they return to Turkey after studying or working abroad can have “dire consequences” for science. Ünal emphasizes that he speaks for himself, not for TASSA.

    “There is quite a bit of arbitrariness to what is going on in general in Turkey,” says Zehra Sayers, a biophysicist at Sabancı. “When the information you have is incomplete, a lot of things seem bizarre.”

    Above the fray

    Why have Sabancı and some other universities hovered above the fray? “The government probably has its own screening methods,” says Saçlıoğlu. Many academics credit their university rectors with protecting them. Sayers and Saçlıoğlu also note that Sabancı is “apolitical” and has been “well governed.” Avni Aksoy, deputy director of the Institute of Accelerator Technologies at Ankara University, posits that the established universities have existed under different governments and “therefore had balanced relations with all the previous government groups.” For the most part, it’s the older, more elite institutions that feel the heat less.

    2
    MIDDLE EAST TECHNICAL UNIVERSITY
    The Middle East Technical University in Ankara, among the best engineering schools in the region, is an oasis for faculty and students during tough times in Turkey. The pedestrian boulevard running through its campus is more than 2 km long.

    Despite the uncertainties, there are notable bright spots for Turkish science: Last year the country joined CERN as an associate member, with annual dues of about $4 million. And Turkey is a founding member of SESAME, the regional synchrotron light source soon to open in Jordan (see the story on page 32). “Both projects help to integrate Turkish physicists and scientists with Europe and the Middle East, consistent with Turkey’s broader traditional role,” says Alp.

    Some new scientific facilities are relative oases. For example, the $60 million Turkish Accelerator and Radiation Laboratory in Ankara, with an IR free-electron laser (FEL) as the centerpiece, is set to begin operations in 2019 and will be open to scientists from anywhere. If the laboratory is successful, it would pave the way for additional facilities—a synchrotron light source, x-ray FEL, positron–electron collider, and proton source—to create a geographically distributed Turkish accelerator center.

    The biggest challenge for research centers, says Aksoy, is that they are not autonomous. Despite recent legislation, for example, he cannot hire people because of a labyrinthine bureaucracy and unclear authorization paths. “That’s our weakness,” he says, “and because of it, we have brain drain.”

    No immunity

    Even places that have not seen firings or mass investigations of faculty have not been immune to the country’s turmoil. Immediately following the July coup attempt, for example, many academics who were abroad were called back to Turkey by the government. As public employees, they had little choice; the penalty for noncompliance is unknown, but Turkish scientists assume it could consist of losing passports, facing legal action, and being fired. Unfortunately, says Sayers, “our times are such that we are becoming paranoiac about every word we use and also worried about jeopardizing our institutions.”

    After the failed coup, the Scientific and Technological Research Council of Turkey (TÜBİTAK), the country’s main research funding agency—which itself was purged of many employees with suspected connections to Gülen—suspended grants and delayed until next year a call for new proposals. For a few months, until TÜBİTAK announced in October that it would resume paying graduate stipends, some faculty members paid graduate students and staff out of their own pockets. For now, the researchers who are faring best are those who are in collaborations funded by the European Union.

    Although R&D spending has been growing in Turkey, in the past few years it has stalled shy of 1% as a percentage of GDP. In 2005 the government announced a goal of investing 3% of GDP by 2013, but by 2010 the target had slid to 2023 (as the Turkish Republic’s centenary, a symbolic date); in 2015 the R&D investment goal was revised down to 2%. But even that target seems elusive, says Alp. “The institutional mechanisms and a road map for implementing ambitious scientific and technological projects are lacking.” Despite the fact that TÜBİTAK has increased money for research, the evaluation and distribution of funding has become biased and arbitrary “and finally paralyzed” by the attempted coup, says Sabancı astrophysicist Ali Alpar.

    In 2011, when the government decided that members of the Turkish Academy of Sciences would be appointed rather than elected on their merits, a majority of members quit, including Alpar. The defectors founded the independent Science Academy, which is funded by member fees and private donors. The new academy’s success has been a surprise, says Saçlıoğlu: “Each year we award some 40 young scientists with two-year research grants. That is one thing of which we are proud.”

    On 29 October, the government decreed that all university rectors will be appointed by Erdoğan. The Science Academy board responded with a statement saying the measure “is tantamount to the eradication of university autonomy.”

    Before the coup attempt, “Turkey was experiencing brain gain,” says Ünal. In one program, TÜBİTAK promised $3000 a month for a year to returning early-career academics. Ünal warns that “after the attempted coup, Turkey again may see brain drain; many academicians are looking for positions in universities abroad.”

    “The most capable, the most easily employable, they are the ranks that will be depleted first,” says Saçlıoğlu. Two decades ago he would tell his students, “Sure, you can do better science abroad, but you can do good things here too.” Now he is more reluctant to encourage them to stay in the country, he says, although “I am not at the point where I would say, ‘You are crazy to stay here.’ ”

    Staying connected

    Over the past year or so, international conferences and workshops in Turkey have been canceled, mainly because speakers and participants are scared off by political events and terrorist attacks. “People who already know us, they come,” says Aksoy, adding that he would say Turkey is not more dangerous than France or Germany. Serkant Ҫetin, a particle physicist at Istanbul Bilgi University, was the national organizer for a CERN accelerator school that was supposed to be held in Istanbul in September; the school was delayed and moved to Hungary. According to Ҫetin, such cancellations have a big impact on scientific life. “Scientists feel their relations to the world are at a lower level, that they are no longer in the loop. People have lost motivation. It’s like a pause button has been pushed. The uncertainty is a shock.”

    “I am aware of people who were under investigation, and who were cleared 100%, but were not given back their positions,” Ҫetin continues. “I have collaborators from other cities who had such cases. They cannot travel abroad. Their passports are deactivated. Even if they start their jobs again tomorrow, the psychological healing will be hard.”

    And worst of all, says Ҫetin, “is what I see in young people, those who recently finished their PhDs. They want to see a future. I see the hope getting lost in their eyes.”

    See the full article here .

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    The mission of Physics Today is to be a unifying influence for the diverse areas of physics and the physics-related sciences.

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    • by providing authoritative, engaging coverage of physical science research and its applications without regard to disciplinary boundaries;
    • by providing authoritative, engaging coverage of the often complex interactions of the physical sciences with each other and with other spheres of human endeavor; and
    • by providing a forum for the exchange of ideas within the scientific community.”

     
  • richardmitnick 2:06 pm on December 8, 2016 Permalink | Reply
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    From Physics Today: “Italy’s chain of earthquakes poses a forecasting challenge” 

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    Physics Today

    07 December 2016
    Seth Stein
    Antonella Peresan
    Edward Brooks

    To develop better hazard maps that will help protect buildings and save lives, scientists are poring over data on the string of Italian quakes that have occurred this year.

    Over the past several months, Italy has experienced a series of destructive earthquakes, which illustrate how the country is splitting geologically along the Apennines, a mountain range that forms the north–south spine of the Italian peninsula.

    The first quake, of magnitude 6.2, occurred on 24 August near the mountain town of Amatrice, about 120 km northeast of Rome. Almost 300 people were killed, and thousands were left homeless. Amatrice’s historic center, with buildings dating from the Middle Ages, was destroyed. Aftershocks continued for months. On 26 October, magnitude 5.5 and 6.1 earthquakes occurred about 30 km to the north. The temblors knocked down electrical and telephone lines, damaged buildings, and frightened local residents already unnerved by continuing earthquakes.

    Four days later, on 30 October, the strongest earthquake to date, magnitude 6.6, struck close to the historic walled town of Norcia, 20 km north of Amatrice. The town’s 14th-century basilica of San Benedetto collapsed, leaving just the façade standing. Fortunately, because many residents of the area had been evacuated due to the recent earthquakes, no lives were lost. However, damage was widespread. “Everything has been destroyed,” one local mayor said. “The towns no longer exist.”

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    A magnitude 6.2 earthquake on 24 August caused buildings to collapse in Pescara del Tronto, located about 15 km from the epicenter. Credit: Marco Garbin, CRS–OGS, Trieste, Italy

    The earthquakes came as no surprise. Similar sequences have been relatively common in the region, which was also shattered by a series of three large quakes in 1703. But unlike three centuries ago, scientists now have the tools to analyze the ground shaking and assess the possibility of further damage. The work is vitally important for helping Italy’s national and local governments rebuild damaged areas and prepare for future earthquakes.

    Battle of the microplates

    Italy’s complicated geological setting underlies the region’s seismic activity. For the past 100 million years, the African plate has been moving northward relative to the Eurasian plate (see diagram below). The collision between the two plates built the Alps and gave rise to a number of distinct crustal blocks, or microplates, which jostle between the two major plates. The Adria microplate, which contains the Adriatic Sea, looks like a finger driven into the Eurasian plate. It is bordered on the west by the Apennines and on the east by the Dinarides, a mountain chain that runs along the east shore of the Adriatic.

    Adria and Eurasia have had a complex history of interactions. Starting about 15 million years ago, the Tyrrhenian Sea, west of Italy, opened by seafloor spreading. Italy rotated counterclockwise relative to Eurasia, and Adria subducted southwestward under Italy, all of which combined to raise the Apennines. About 2 million years ago, spreading ceased in the Tyrrhenian Sea, and the subduction stopped. As a result, Italy west of the Apennines became part of Eurasia, and Adria began moving northwestward with respect to Eurasia.

    All that jostling explains a lot about earthquakes in Italy. Positions measured with high-precision GPS data show Adria rotating counterclockwise about a rotation pole in the southwestern Alps. That motion causes extensional earthquakes in the Apennines, where Adria is diverging from Eurasia, and compressional earthquakes along the southeastern Alps and Dinarides, where Adria is colliding with Eurasia.

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    Italy lies in an active geological zone. Red lines are plate boundaries, red dots are earthquakes with magnitude greater than 5 that have occurred since 1966, and yellow dots are epicenters of the 2016 earthquake series and the 2009 L’Aquila earthquake. The arrows show plate motions with respect to Eurasia. The Adria plate rotates with respect to Eurasia along the pole indicated by the star.

    The Apennine earthquakes occur on a network of short (30–40 km in length) faults that formed about a million years ago, relatively recently by geological standards. Over time, fault systems become smoother as short faults merge into longer ones. Because earthquake magnitudes are controlled by fault length, the strongest earthquakes on the Apennine faults have magnitudes between 6 and 7. Instead of growing stronger, the earthquakes on one fault segment often trigger earthquakes on a nearby fault, because the change in the stress field after an earthquake makes a nearby fault more prone to slip.

    The process of fault interactions by stress transfer is thought to be why Apennine earthquakes occur in progressive sequences, much like a series of falling dominoes. The recent activity can be viewed as a northward-propagating sequence that started with the 2009 magnitude 6.3 earthquake that destroyed the city of L’Aquila, about 50 km south of Amatrice. Italian seismologists were charged with manslaughter for allegedly providing inaccurate information about the earthquake danger, though they were ultimately acquitted.

    Playing the game of chance

    The burst of activity over the last seven years illustrates the challenge Italy faces in dealing with earthquakes. Defending society against earthquakes is a high-stakes game of chance against nature in an uncertain world. It involves the scientific challenge of assessing the hazard—estimating what levels of shaking should be expected and how often—and the societal challenge of mitigating or reducing the resulting losses.

    Both challenges are complex. Italy’s current seismic hazard maps were developed using a probabilistic approach, which predicts the level of shaking that should be exceeded either 2% or 10% of the time over a 50-year period. The maps show the Apennines as an area of high seismic hazard. However, ground shaking for the 30 October event was significantly more severe at several sites than the maps predicted. A deterministic approach to hazard mapping, which specifies the largest potential shaking to expect, better matched the observations of most severe shaking.

    Because earthquake hazard mapping has only been developed in the past 40 years, and large earthquakes are relatively rare, seismologists do not yet understand the accuracies and uncertainties of the maps. Programs are under way in Italy and other countries to assess and improve hazard mapping, since governments use the maps to develop building codes for earthquake-resistant construction. That’s especially important in Italy, which is full of historic buildings that are not particularly structurally sound and very expensive to retrofit.

    Although major earthquakes rarely occur at any given place, Italy as a whole has had more than its fair share. In addition to the 2009 and 2016 events, the country has experienced at least three other destructive quakes in the last two decades. All that seismic activity demonstrates the need for seismologists, earthquake engineers, social scientists, and public officials to work together to assess and mitigate earthquake hazards. As those experts raise and debate the hard questions, they will work toward better protection against quakes.

    Seth Stein and Edward Brooks are seismologists at Northwestern University in Evanston, Illinois. Antonella Peresan is a seismologist at the National Institute of Oceanography and Experimental Geophysics in Trieste, Italy.

    See the full article here .

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    The mission of Physics Today is to be a unifying influence for the diverse areas of physics and the physics-related sciences.

    It does that in three ways:

    • by providing authoritative, engaging coverage of physical science research and its applications without regard to disciplinary boundaries;
    • by providing authoritative, engaging coverage of the often complex interactions of the physical sciences with each other and with other spheres of human endeavor; and
    • by providing a forum for the exchange of ideas within the scientific community.”

     
  • richardmitnick 7:56 pm on October 6, 2016 Permalink | Reply
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    From Physics Today: “A bridge too far: The demise of the Superconducting Super Collider” A very important article. 

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    Physics Today

    10.6.16
    Michael Riordan

    The largest basic scientific project ever attempted, the supercollider proved to be beyond the management capacity of the US high-energy physics community. A smaller proton collider would have been substantially more achievable.

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    Map of the proposed Superconducting Super Collider.

    When the US Congress terminated the Superconducting Super Collider (SSC) in October 1993 after about $2 billion had been spent on the project, it ended more than four decades of American leadership in high-energy physics. To be sure, US hegemony in the discipline had been deteriorating for more than a decade, but the SSC cancellation was the ultimate blow that put Europe unquestionably in the driver’s seat and opened the door to the discovery of the Higgs boson at CERN (see Physics Today, September 2012, page 12). The causes and consequences of the SSC’s collapse, a watershed event in the history of science, have been discussed and debated ever since it happened.

    At least a dozen good reasons have been suggested for the demise of the SSC. Primary among them are the project’s continuing cost overruns, its lack of significant foreign contributions, and the end of the Cold War. But recent research and documents that have come to light have led me to an important new conclusion: The project was just too large and too expensive to have been pursued primarily by a single nation, however wealthy and powerful. Wolfgang “Pief” Panofsky, founding director of SLAC, voiced that possibility during a private conversation in the months after the project’s demise; he suggested that perhaps the SSC project was “a bridge too far” for US high-energy physics. That phrase became lodged firmly in my mind throughout the many years I was researching its history.

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    View along the Superconducting Super Collider main-ring tunnel, in early 1993. (Courtesy of Fermilab Archives.)

    Some physicists will counter that the SSC was in fact being pursued as an international project, with the US taking the lead in anticipation that other nations would follow; it had done so on large physics projects in the past and was doing so with the much costlier International Space Station. But that argument ignores the inconvenient truth that the gargantuan project was launched by the Reagan administration as a deliberate attempt to reestablish US leadership in a scientific discipline the nation had long dominated. If other nations were to become involved, they would have had to do so as junior partners in a multibillion-dollar enterprise led by US physicists.

    That fateful decision, made by the leader of the world’s most powerful government, established the founding rhetoric for the SSC project, which proved difficult to abandon when it came time to enlist foreign partners.

    The SSC and the LHC

    In contrast, CERN followed a genuinely international approach in the design and construction of its successful Large Hadron Collider (LHC), albeit at a much more leisurely pace than had been the case for the SSC.

    CERN/LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    Serious design efforts begun during the late 1980s and early 1990s ramped up after the SSC’s termination. Although the LHC project also experienced trying growth problems and cost overruns—its cost increased from an estimated 2.8 billion Swiss francs ($2.3 billion at the time) in 1996 to more than 4.3 billion Swiss francs in 2009—it managed to survive and become the machine that allowed the Higgs-boson discovery using only about half of its originally designed 14 TeV energy.

    CERN CMS Higgs Event
    CERN CMS Higgs Event

    CERN ATLAS Higgs Event
    CERN ATLAS Higgs Event

    (The SSC, by comparison, was designed for 40 TeV collision energy.) When labor costs and in-kind contributions from participating nations are included, the total LHC price tag approached $10 billion, a figure often given in the press. Having faced problems similar to, though not as severe as, what the SSC project experienced, the LHC’s completion raises an obvious question: Why did CERN and its partner nations succeed where the US had failed?

    From the SSC’s early days, many scientists thought it should have been sited at or near Fermilab to take advantage of the existing infrastructure, both physical and human. University of Chicago physicist and Nobel laureate James Cronin explicitly stated that opinion in a letter he circulated to his fellow high-energy physicists in August 1988. CERN has followed that approach for decades, building one machine after another as extensions of its existing facilities and reusing parts of the older machines in new projects, thereby reducing costs. Perhaps as important, CERN had also gathered and developed some of the world’s most experienced accelerator physicists and engineers, who work together well. During the late 1980s, Fermilab had equally adept machine builders—plus substantial physical infrastructure—who could have turned to other productive endeavors when the inevitable funding shortfalls occurred during the annual congressional appropriations process.

    Troublesome clashes occurred at the SSC between the high-energy physicists and engineers who had been recruited largely from the shrinking US military–industrial complex as the Cold War wound down during the late 1980s and early 1990s. For example, the methods by which SSC general manager Edward Siskin and magnet division director Thomas Bush managed large projects and developed sophisticated components differed greatly from those customarily employed by high-energy physicists. A particular bone of contention was the project’s initial lack of a cost-and-schedule control system, which by then had become mandatory practice for managing large military-construction and development projects overseen by the Department of Defense. Such clashes would probably not have erupted in the already well-integrated Fermilab high-energy physicist culture, nor would the disagreements have been as severe.

    Those pro-Fermilab arguments, however, ignore the grim realities of the American political process. A lucrative new project that was to cost more than $5 billion and promised more than 2000 high-tech jobs could not be sole-sourced to an existing US laboratory, no matter how powerful its state congressional delegation. As politically astute leaders of the Department of Energy recognized, the SSC project had to be offered up to all states able to provide a suitable site, with the decision based (at least publicly) on objective, rational criteria. Given the political climate of the mid 1980s, a smaller project costing less than $1 billion and billed as an upgrade of existing facilities might have been sole-sourced to Fermilab, but not one as prominent and costly as the SSC. It had to be placed on the US auction block, and Texas made the best bid according to the official DOE criteria.

    Unlike the SSC, the LHC project benefited from the project management skills of a single physicist, Lyndon Evans, who came to the task with decades of experience on proton colliders. Despite the facility’s major problems and cost overruns, Evans enjoyed the strong support of the CERN management and a deeply experienced cadre of physicists and engineers. On the LHC project, engineers reported ultimately to physicists, who as the eventual users of the machine were best able to make the required tradeoffs when events did not transpire as originally planned. The project encountered daunting difficulties and major delays, including the September 2008 quench of dozens of superconducting magnets. But the core management team led by Evans worked through those problems, shared a common technological culture, and understood and supported the project’s principal scientific goals.

    Similar observations cannot be made regarding the military–industrial engineers who came to dominate the SSC lab’s collider construction. Until 1992 a succession of acting or ineffectual project managers could not come to grips with the demands of such a complex, enormous project that involved making countless decisions weekly. Secretary of energy James D. Watkins deliberately had Siskin inserted into the SSC management structure in late 1990 in an effort to wrest control of the project from the high-energy physicists. After SLAC physicist John Rees stepped in as the SSC project manager in 1992, he and Siskin began working together effectively and finally got a computerized cost-and-schedule control system up and running—and thus the project under better control. But it proved to be too late, as the SSC had already gained a hard-to-shake reputation in Congress as being mismanaged and out of control.

    CERN also enjoys an enviable internal structure, overseen by its governing council, that largely insulates its leaders and scientists from the inevitable political infighting and machinations of member nations. Unlike in the US, the director general or project manager could not be subpoenaed to appear before a parliamentary investigations subcommittee or be required to testify under oath about its management lapses or cost overruns—as SSC director Roy Schwitters had to do before Congress. Nor did the LHC project face annual congressional appropriations battles and threats of termination, as did major US projects like the SSC and the space station. Serious problems that arose with the LHC—for example, a large cost overrun in 2001—were addressed in the council, which represents the relevant ministries of its member nations and generally operates by consensus, especially on major laboratory initiatives. That supple governing structure helps keep control of a project within the hands of the scientists involved and hinders government officials from intervening directly.

    Because the council must also address the wider interests of individual European ministries, CERN leaders have to be sensitive to the pressures that the annual budget, new projects, and cost overruns can exert on other worthy science. In that manner, European scientists in other disciplines have a valuable voice in CERN governing circles. The LHC project consequently had to be tailored to address such concerns before the council would grant it final approval. In the US, the only mechanism available was for disgruntled scientists to complain openly, which Philip Anderson of Princeton University, Theodore Geballe of Stanford University, Rustum Roy of the Pennsylvania State University, and others did in prominent guest editorials or in congressional hearings when SSC costs got out of hand between 1989 and 1991. The resulting polarization of the US physics community helped undermine what had been fairly broad support for the SSC project in the House of Representatives, which in 1989 had voted 331–92 to proceed with construction.

    Because of financial pressures, CERN had to effectively internationalize the LHC project—obtaining monetary and material commitments from such nonmember nations as Canada, China, India, Japan, Russia and the US—before the council would give approval to go ahead with it. When that approval finally came in 1996, the LHC was a truly international scientific project with firm financial backing from more than 20 nations. Those contributions enabled Evans and his colleagues to proceed with the design of a collider able to reach the full 14 TeV collision energy as originally planned.

    Scale matters

    In hindsight, the LHC was (somewhat fortuitously) more appropriately sized to its primary scientific goal: the discovery of the Higgs boson. The possibility that this elusive quarry could turn up at a mass as low as 125 GeV was not widely appreciated until the late 1980s, when theories involving supersymmetry began to suggest the possibility of such a light Higgs boson emerging from collisions. But by then the SSC die had been cast in favor of a gargantuan 40 TeV collider, 87 km in circumference, that would be able to uncover the roots of spontaneous symmetry breaking even if the long-anticipated phenomenon required the protons’ constituent quarks and gluons to collide with energies9 as high as 2 TeV. When it became apparent in late 1989 that roughly $2 billion more would be needed to reduce design risks that could make it difficult for the SSC to attain its intended collision rate, Panofsky argued that the project should be down-scoped to 35 TeV to save hundreds of millions of dollars. But nearly everyone else countered that the full 40 TeV was required to make sure users could discover the Higgs boson—or whatever else was responsible for spontaneous symmetry breaking and elementary-particle masses.

    3
    Schematic of the Superconducting Super Collider, depicting its main 87 km ring—designed to circulate and collide twin proton beams, each at energies up to 20 TeV—the injector accelerators, and experimental halls, where the protons were to collide. That ring circumference is more than three times the 27 km circumference of CERN’s Large Hadron Collider (orange). The footprints of yet smaller particle colliders at Fermilab (purple) and SLAC (green) are also shown for comparison.

    A US High-Energy Physics Advisory Panel (HEPAP) subpanel, chaired by SLAC deputy director Sidney Drell, unanimously endorsed that fateful decision in 1990. The US high-energy physics community had thus committed itself to an enormous project that became increasingly difficult to sustain politically amid the worsening fiscal climate of the early 1990s. With the end of the Cold War and subsequent absence of a hoped-for peace dividend during a stubborn recession, the US entered a period of fiscal austerity not unlike what is now occurring in many developed Western nations. In that constrained environment, a poorly understood basic-science project experiencing large, continuing cost overruns and lacking major foreign contributions presented an easy political target for congressional budget cutters.

    A 20 TeV proton collider—or perhaps just a billion-dollar extension of existing facilities such as the 4–5 TeV Dedicated Collider proposed by Fermilab in 1983—would likely have survived the budget axe and discovered the light Higgs boson long ago. Indeed, another option on the table during the 1983 meetings of a HEPAP subpanel chaired by Stanford physicist Stanley Wojcicki was for Brookhaven National Laboratory to continue construction of its Isabelle collider while Fermilab began the design work on that intermediate-energy proton– antiproton collider, whose costs were then projected at about $600 million.

    That more conservative, gradual approach would have maintained the high-energy physics research productivity of the DOE laboratories for at least another decade. And such smaller projects would certainly have been more defensible during the economic contractions of the early 1990s, for they aligned better with the high-energy physics community’s diminishing political influence in Washington. Their construction would also have been far easier for physicists to manage and control by themselves without having to involve military–industrial engineers.

    The Wojcicki subpanel had originally recommended that the US design a 20–40 TeV collider, but that was before European physicists led by CERN decided in 1984 to focus their long-range plans on a 14 TeV proton collider that they could eventually achieve by adding superconducting magnets to the Large Electron–Positron Collider (LEP) then under construction. (Actually, they considered 18 TeV achievable when they made this decision.) Lowering the SSC energy as Panofsky suggested thus risked Congress raising the awkward question that had already been voiced by SSC opponents, “Why don’t US physicists just join the LHC project and save US taxpayers billions of dollars?” Although justified on purely physics grounds, the 1990 decision to keep the original SSC energy clearly had a significant political dimension, too.

    The US high-energy physics community therefore elected to “bet the company” on an extremely ambitious 40 TeV collider, so large that it ultimately had to be sited at a new laboratory in the American Southwest, as was originally envisioned in 1982. Such a choice, however, meant abandoning the three-laboratory DOE system that had worked well for nearly two decades and had fostered US leadership in high-energy physics. (That was Cronin’s primary concern when he urged his fellow physicists and DOE to site the SSC at Fermilab.) But perceived European threats to US hegemony and Reagan administration encouragement tipped the balance toward making the SSC a national project and away from it becoming the truly international “world laboratory” that others had long been advocating.

    Infrastructure problems

    In retrospect, the SSC leadership faced two daunting tasks in establishing a new high-energy physics laboratory in Waxahachie, Texas:

    ► Building the physical infrastructure for a laboratory that would cost billions of US taxpayer dollars and was certain to be a highly visible, contentious project.

    ► Organizing the human infrastructure needed to ensure that the SSC became a world-class laboratory where scientists could do breakthrough high-energy physics research.

    Addressing those tasks meant having to draw resources away from other worthy programs and projects that competed with the SSC during a period of tight annual budgets. Reagan administration officials had insisted that the project would be funded by new money, but that was only a convenient fiction. Congress, not the president, holds the federal purse strings, so the SSC always had to compete against other powerful interests—especially energy and water projects—for its annual funding. And it usually came up short, which further delayed the project and increased its costs.

    Schwitters and other managers attempted to attract top-notch physicists to staff the laboratory, but after 1988 many of its original, primary advocates in the SSC Central Design Group (CDG) returned to their tenured positions in universities and national labs. For example, CDG director Maury Tigner, who returned to Cornell University, might have been the best choice for the original project manager. (Second-tier CDG managers did go to Texas, however, as did many younger, untenured physicists.) Despite the promise and likely prestige of building a world-class scientific laboratory, the Dallas–Fort Worth area was viewed as an intellectual backwater by many older, accomplished high-energy physicists. They might have come to work there on a temporary or consulting basis, as did Rees originally, but making a permanent, full-time commitment and bringing their spouses and families with them proved a difficult choice for many.

    Achieving the first daunting task in a cost-effective way thus required bringing in an alien, military–industrial culture that made realizing the second task much more difficult. Teaming with EG&G and Sverdrup Corporations helped the SSC laboratory to tap the growing surplus of military–industrial engineers. It was crucial to get capable engineers working on the project quickly so that all the detailed design and construction work could occur on schedule and costs could be controlled. But the presence of military–industrial engineers at high levels in the SSC organization served as an added deterrent to established physicists who might otherwise have moved to Texas to help organize and build the laboratory.

    Estimates of the infrastructure costs that could have been saved by siting the SSC adjacent to Fermilab range from $495 million to $3.28 billion. The official DOE figures came in at the lower end, from $495 million to $1.03 billion, but they ignored the value of the human infrastructure then available at Fermilab. In hindsight, the costs of establishing such infrastructure anew at a green-field site were not small. In Tunnel Visions, my coauthors and I estimate that the total added infrastructure costs—physical plus human—of building the SSC in Texas would have been about $2 billion.

    Unlike historians gazing into the past, however, physicists do not enjoy the benefit of hindsight when planning a new machine. Guided in part by the dominant theoretical paradigm, they work with a cloudy crystal ball through which they can only guess at phenomena likely to occur in a new energy range, and they must plan accordingly. And few can foresee what may transpire in the economic or political realms that could jeopardize an enormous project that requires about a decade to complete and will cost billions of dollars, euros, or Swiss francs—or, relevant today, a trillion yen. That climate of uncertainty thus argues for erring on the side of fiscal conservatism and for trying to reduce expenses by building a new machine at or near an existing laboratory. Such a gradual, incremental approach has been followed successfully at CERN for six decades now, and to a lesser extent at other high-energy physics labs.

    But US physicists, perhaps enticed by Reagan administration promises, elected to stray from that well-worn path in the case of the SSC. It took a giant leap of faith to imagine that they could construct an enormous new collider at a green-field site where everything had to be assembled from scratch—including the SSC management team—and defend the project before Congress in times of increasing fiscal austerity. A more modest project sited at Fermilab would likely have weathered less opposition and still be operating today.

    In the multibillion-dollar realm it had entered, the US high-energy physics community had to form uneasy alliances with powerful players in Washington and across the nation. And those alliances involved uncomfortable compromises that led, directly or indirectly, to the SSC project’s demise. That community of a few thousand physicists had a small and diminishing supply of what Beltway insiders recognize as “political capital.” It could not by itself lay claim to more than 5 billion taxpayer dollars when many other pressing demands were being made on the federal purse. Thus for the SSC to move forward as a principally national project meant that those physicists had to give up substantial control to powerful partners with their own competing agendas. The Texans’ yearning for high-tech jobs, for example, helped congressional opponents paint the SSC as a pork-barrel project in the public mind. In the process, the high-energy physics community effectively lost control of its most important project.

    A personal perspective

    Part of the problem driving up the SSC costs was the project’s founding rhetoric: the intention to leapfrog European advances and reassert US leadership in high-energy physics. The Reagan administration in particular was promoting US competitiveness over international cooperation; treating other nations as equal partners would not have gained the administration’s support. And a smaller, say 20 TeV, proton collider would not have sufficed either, for that was much too close in energy to what CERN could eventually achieve in the 27 km LEP tunnel then under construction. The SSC therefore had to shoot for 40 TeV, which was presented as a scientific necessity but was in fact mainly a political choice. That energy was more than 20 times the energy of the Fermilab Tevatron, and the SSC proved to be nearly 20 times as expensive. And along with its onerous price tag came other, unanticipated complications—managerial as well as political—that US physicists were ill-equipped to confront. As Panofsky suggested, the SSC was indeed “a bridge too far”—a phrase he probably borrowed from the title of Cornelius Ryan’s 1974 book about a disastrous Allied campaign to capture the Arnhem Bridge over the Rhine River during World War II.

    I became convinced of that interpretation only in April 2014, when previously suppressed documents surfaced at the William J. Clinton Presidential Library. The documents were memos to Clinton’s chief of staff regarding a draft letter being circulated among top administration officials in early 1993 by new secretary of energy Hazel O’Leary. In the letter, Clinton was to request a billion-dollar SSC contribution from Japanese prime minister Kiichi Miyazawa. Such a contribution would have helped tremendously to reassure House members that major foreign support was indeed forthcoming and perhaps would have kept the project alive. But the memos, one from science adviser John Gibbons and the other from assistant to the president John Podesta and staff secretary Todd Stern, recommended against the president sending such a letter. The latter memo was particularly adamant:

    NSC [the National Security Council] agrees that we should convey to the Japanese our firm backing for the SSC, but still objects strongly [emphasis in the original] to sending a letter to Miyazawa. Such a letter could be seen as suggesting that we attach greater importance to Japanese participation in the SSC than we do to Japanese efforts on other fronts, such as aid to Russia.

    The document underscored for me what insurmountable competition the SSC faced in securing the required billions of dollars in federal and foreign funding. Despite their political influence reaching back to the years after World War II, high-energy physicists were not accustomed to playing in the major leagues of US politics. No such letter was ever sent.

    In the final analysis, the Cold War model of doing Big Science projects, with the US taking the lead unilaterally and expecting other Western nations to follow in its footsteps, was no longer appropriate. By the 1980s the global scientific community had begun an epochal transition into a multipolar world in which other nations expect to be treated as equal partners in such major scientific endeavors—especially considering the large financial contributions involved. As US high-energy physicists have hopefully learned from the 1993 termination of the SSC, it should have been promoted from day one as a genuinely international world-laboratory project.

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    From Physics Today: “Water flows freely through carbon nanotubes” 

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    Physics Today

    08 September 2016
    Andrew Grant

    A new experiment confirms the slipperiness of the minuscule carbon cylinders but not their boron nitride counterparts.

    Despite the frenzy of research into carbon nanotubes (CNTs) over the past few decades (see, for example, Physics Today, June 1996, page 26), there isn’t much experimental evidence for one of the tiny structures’ most talked-about superpower­s: the ability to funnel water with nearly zero friction. The problem has been achieving the sensitivity to measure water transport rates as feeble as a femtoliter a second. Now Lydéric Bocquet and his colleagues at École Normale Supérieure in Paris have confirmed the slipperiness of CNTs by directly measuring water flow through individual nanotubes whose bores ranged from 15 nm to 50 nm. The researchers stuck a multiwalled CNT inside a small pipette and essentially turned the nanotube into the needle of a syringe. Pressure applied inside the pipette caused water to flow through the CNT and into a tank of water. Rather than tracking the water as it flowed through the tube, Bocquet and his team analyzed the motion of suspended polystyrene nanobeads in the tank to deduce the strength of the jet emerging from the CNT (see image below, which shows the response at various pressures). The results verify that CNTs allow water to flow extremely efficiently. Bocquet’s team also confirmed its 2010 prediction that the flow rate would increase as the tube’s radius decreased, although the dependence turned out to be roughly quadratic rather than quartic. The biggest surprise came when the researchers replaced the CNTs with nanotubes of boron nitride. Although the BN tubes are nearly structurally identical to their carbon counterparts (see Physics Today, November 2010, page 34), they proved far more resistant to water flow. The finding seems to suggest that electronic properties—CNTs are conductors; boron nitride nanotubes are insulators—play a role in hydrodynamics at very small scales. Bocquet and his team plan to investigate that possibility as they explore the nanotubes’ potential for applications such as water distillation and filtration. (E. Secchi et al., Nature 537, 210, 2016.)

    1

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    From Physics Today: “Six reasons to get excited about neutrinos” 

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    Physics Today

    23 August 2016
    Andrew Grant

    Extra Dimensions: New results and upcoming experiments offer hope that neutrinos hold the key to expanding the standard model.

    The headlines from the recent International Conference on High Energy Physics (ICHEP) in Chicago trended sad, focused on the dearth of discoveries from the Large Hadron Collider. (See, for example, “Prospective particle disappears in new LHC data.”) Yet there was some optimism to be found in the Windy City, particularly among neutrino physicists. Here are six reasons to believe that neutrinos might provide the window into new physics that the LHC has not:

    Neutrinos are proof that the standard model is wrong. Sure, we know that dark matter and dark energy are missing from the standard model. But neutrinos are standard-model members, and the theoretical predictions are wrong. Prevailing theory says that neutrinos are massless; the Nobel-winning experiments at the Sudbury Neutrino Observatory and Super-Kamiokande demonstrated definitively that neutrinos oscillate between three flavors (electron, muon, and tau) and thus have mass. André de Gouvêa, a theoretical physicist at Northwestern University, deems neutrinos the “only palpable evidence of physics beyond the standard model.” Everything we learn about neutrinos in the coming years is new physics.

    1
    This signal from May 2014 denotes the detection of an electron neutrino by Fermilab’s NOvA experiment. Credit: NOvA Neutrino Experiment.

    FNAL/NOvA experiment
    FNAL/NOvA experiment map

    Neutrinos’ ability to morph from one flavor to another is only now starting to be understood. Each of neutrinos’ three flavors is actually a quantum superposition of three different mass states. By understanding the interplay of the three mass states, characterized by parameters called mixing angles, physicists can pin down how neutrinos transform between flavors. Fresh data from the NOvA experiment at Fermilab near Chicago suggest that neutrino mixing may not be as simple as most theories predict.

    Neutrinos may exhibit charge conjugation–parity (CP) violation. All known examples of CP violation, in which particle decays proceed differently with matter than with antimatter, take place in processes involving quark-containing particles like kaons and B mesons. But at the Neutrino 2016 meeting in London and at ICHEP, the T2K experiment offered fresh data hinting at matter–antimatter asymmetry for neutrinos.

    T2K Experiment
    Super-Kamiokande
    T2K map
    T2K Experiment

    After firing beams of muon neutrinos and antineutrinos at the Super-Kamiokande detector in Japan, scientists expected to detect 23 electron neutrinos and 7 electron antineutrinos; instead they have spotted 32 and 4, respectively. T2K isn’t anywhere close to achieving a 5 σ result, but the evidence for CP violation seems to be growing as the experiment acquires more data.

    Neutrinos may be the first fundamental particles that are Majorana fermions. Because the neutrino is the only fermion that is electrically neutral, it is also the only one that could be a Majorana fermion, a particle that is identical to its antiparticle. Learning whether neutrinos are Majorana particles or typical Dirac fermions would provide invaluable insight as to how neutrinos acquired mass at the dawn of the universe, de Gouvêa says. To determine the nature of neutrinos, physicists are hunting for a process called neutrinoless double beta decay. In typical double beta decay, two neutrons transform into protons and emit a pair of antineutrinos. If those antineutrinos are Majorana particles, they could annihilate each other. A 16 August paper from the KamLAND-Zen experiment in Japan reports the most stringent limits for the rate of neutrinoless double beta decay, further constraining the possibility that neutrinos are Majorana particles.

    Another neutrino flavor may be waiting to be discovered. The discovery of a fourth neutrino flavor, the sterile neutrino, would make every particle physicist forget about the LHC’s particle drought. Such a neutrino could enable physicists to explain dark matter or the absence of antimatter in the universe. The Antarctic detector IceCube just reported a negative result in the hunt for a sterile neutrino, but results from prior experiments still leave some wiggle room for the particle’s existence.

    Multiple powerful neutrino experiments are on the horizon. The NOvA experiment is up and running and delivering data that, at least so far, seem to complement T2K’s hints of CP violation. Fermilab scientists are already excited about the Deep Underground Neutrino Experiment, which should come on line around 2025.

    FNAL LBNF/DUNE from FNAL to SURF
    FNAL LBNF/DUNE from FNAL to SURF

    Hyper-Kamiokande, a megadetector in Japan with a million-ton tank of water for neutrino detection, should start operations around the same time.

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    From Physics Today: “High-energy lab has high-energy director” 

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    Physics Today

    21 July 2016
    Toni Feder

    CERN director general Fabiola Gianotti looks at what lies ahead for particle physics.

    1
    Fabiola Gianotti in December 2015, just before she became CERN’s director general. Credit: CERN

    Fabiola Gianotti shot to prominence on 4 July 2012, with the announcement of the discovery of the Higgs boson. At the time, she was the spokesperson of ATLAS, which along with the Compact Muon Solenoid (CMS) experiment spotted the Higgs at the Large Hadron Collider (LHC) at CERN.

    CERN ATLAS Higgs Event
    CERN/ATLAS detector
    CERN ATLAS Higgs Event; CERN/ATLAS detector

    CERN CMS Higgs Event
    CERN/CMS Detector
    CERN CMS Higgs Event; CERN/CMS Detector

    In the excitement over the Higgs discovery, Gianotti was on the cover of Time. She was hailed as among the most influential and the most inspirational women of our time. She was listed among the “leading global thinkers of 2013” by Foreign Policy magazine.

    “I am not very comfortable in the limelight,” says Gianotti. “Particle physics is a truly collaborative field. The discovery of the Higgs boson is the result of the work of thousands of physicists over more than 20 years.”

    Gianotti first went to CERN in 1987 as a graduate student at the University of Milan. She has been there ever since. And she seems comfortable at the helm, a job she has held since the beginning of this year.

    “The main challenge is to cope with so many different aspects, and switching my brain instantly from one problem to another one,” she says. “There are many challenges—human challenges, scientific challenges, technological challenges, budget challenges. But the challenges are interesting and engaging.”

    As of this summer, the LHC is in the middle of its second run, known as Run 2. In June the collider reached a record luminosity of 1034 cm−2s−1. It produces proton–proton collisions of energy of 13 TeV. A further push to the design energy of 14 TeV may be made later in Run 2 or in Run 3, which is planned for 2021–23. An upgrade following the third run will increase the LHC’s luminosity by an order of magnitude.

    Physics Today’s Toni Feder caught up with Gianotti in June, about six months into her five-year appointment in CERN’s top job.

    PT: Last fall the ATLAS and CMS experiments both reported hints of a signal at 750 GeV. What would the implications be of finding a particle at that energy?

    GIANOTTI: At the moment, we don’t know if what the experiments observed last year is the first hint of a signal or just a fluctuation. But if the bump turns into a signal, then the implications are extraordinary. Its presumed features would not be something we can classify within the best-known scenarios for physics beyond the standard model. So it would be something unexpected, and for researchers there is nothing more exciting than a surprise.

    The experiments are analyzing the data from this year’s run and will release results in the coming weeks. We can expect them on the time scale of ICHEP in Chicago at the beginning of August. [ICHEP is the International Conference on High Energy Physics.]

    PT: The LHC is up to nearly the originally planned collision energy. The next step is to increase the luminosity. How will that be done?

    GIANOTTI: To increase the luminosity, we will have to replace components of the accelerator—for example, the magnets sitting on each side of the ATLAS and CMS collision regions. These are quadrupoles that squeeze the beams and therefore increase the interaction probability. We will replace them with higher-field, larger-aperture magnets. There are also other things we have to do to upgrade the accelerator. The present schedule for the installation of the hardware components is at the end of Run 3—that is, during the 2024–26 shutdown. The operation of the high-luminosity LHC will start after this installation, so on the time scale of 2027.

    The high-luminosity LHC will allow the experiments to collect 10 times as much data. Improving the precision will be extremely important, in particular for the interaction strength—so-called couplings—of the Higgs boson with other particles. New physics can alter these couplings from the standard-model expectation. Hence the Higgs boson is a door to new physics.

    The high-luminosity LHC will also increase the discovery potential for new physics: Experiments will be able to detect particles with masses 20% to 30% larger than before the upgrade.

    And third, if new physics is discovered at the LHC in Run 2 or Run 3, the high-luminosity LHC will allow the first precise measurements of the new physics to be performed with a very well-known accelerator and very well-known experiments. So it would provide powerful constraints on the underlying theory.

    PT: What are some of the activities at CERN aside from the LHC?

    GIANOTTI: I have spent my scientific career working on high-energy colliders, which are very close to my heart. However, the open questions today in particle physics are difficult and crucial, and there is no single way to attack them. We can’t say today that a high-energy collider is the way to go and let’s forget about other approaches. Or underground experiments are the way to go. Or neutrino experiments are the way to go. There is no exclusive way. I think we have to be very inclusive, and we have to address the outstanding questions with all the approaches that our discipline has developed over the decades.

    In this vein, at CERN we have a scientific diversity program. It includes the study of antimatter through a dedicated facility, the Antiproton Decelerator; precise measurements of rare decays; and many other projects. We also participate in accelerator-based neutrino programs, mainly in the US. And we are doing R&D and design studies for the future high-energy colliders: an electron–positron collider in the multi-TeV region [the Compact Linear Collider] and future circular colliders.

    PT: Japan is the most likely host for a future International Linear Collider, an electron–positron collider (see Physics Today, March 2013, page 23). What’s your sense about whether the ILC will go ahead and whether it’s the best next step for high-energy physics?

    GIANOTTI: Japan is consulting with international partners to see if a global collaboration can be built. It’s a difficult decision to be taken, and it has to be taken by the worldwide community.

    Europe will produce a new road map, the European Strategy for Particle Physics, on the time scale of 2019–20. That will be a good opportunity to think about the future of the discipline, based also on the results from the LHC Run 2 and other facilities in the world.

    PT: How is CERN affected by tight financial situations in member countries?

    GIANOTTI: CERN has been running for many years with a constant budget, with constant revenues from member states, at a level of CHF 1.2 billion [$1.2 billion] per year. We strive to squeeze the operation of the most powerful accelerator in the world, its upgrade, and other interesting projects within this budget.

    PT: Will Brexit affect CERN?

    GIANOTTI: We are not directly affected because CERN membership is not related to being members of the European Union.

    PT: You have said you have four areas that you want to maintain and expand at CERN: science, technology and innovation, education, and peaceful collaboration. Please elaborate.

    GIANOTTI: Science first. We do research in fundamental physics, with the aim of understanding the elementary particles and their interactions, which also gives us very important indications about the structure and evolution of the universe.

    In order to accomplish these scientific goals, we have to develop cutting-edge technologies in many domains, from superconducting magnets to vacuum technology, cryogenics, electronics, computing, et cetera.

    These technologies are transferred to society and find applications in many other sectors—for example, in the medical fields with imaging and cancer therapy, but also solar panels, not to mention the World Wide Web. Fundamental research requires very sophisticated instruments and is a driver of innovation.

    Another component of our mission is education and training. The CERN population is very young: The age distribution of the 12 000 citizens from all over the world working on our experiments peaks at 27 years, and almost 50% are below 35. About half of our PhD students remain in academia or research, and about half go to industry. It is our duty to prepare them to be tomorrow’s scientists or tomorrow’s employees of industry—and in any case, good citizens.

    How do we prepare them to be good citizens? CERN was created in the early 1950s to promote fundamental research and to foster peaceful collaboration among European countries after the war. Today we have scientists of more than 110 nationalities, some from countries that are in conflict with each other, some from countries that do not even recognize each other’s right to exist. And yet they work together in a peaceful way, animated by the same passion for knowledge.

    PT: You are the first woman to head CERN. What do you see as the significance of this?

    GIANOTTI: The CERN director general should be appointed on the basis of his or her capabilities to run the laboratory and not on the basis of gender arguments. This being said, I hope that my being a woman can be useful as an encouragement to girls and young women who would like to do fundamental research but might hesitate. It shows them they have similar opportunities as their male colleagues.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    “Our mission

    The mission of Physics Today is to be a unifying influence for the diverse areas of physics and the physics-related sciences.

    It does that in three ways:

    • by providing authoritative, engaging coverage of physical science research and its applications without regard to disciplinary boundaries;
    • by providing authoritative, engaging coverage of the often complex interactions of the physical sciences with each other and with other spheres of human endeavor; and
    • by providing a forum for the exchange of ideas within the scientific community.”

     
  • richardmitnick 4:48 pm on July 14, 2016 Permalink | Reply
    Tags: , Guiding surgical needles, Physics Today   

    From Physics Today: “Guiding surgical needles” 

    Physics Today bloc

    Physics Today

    14 July 2016
    Charles Day

    1

    Doctors frequently use thin, hollow needles to apply anesthetic to individual nerves, to extract samples of amniotic fluid, and to perform other minimally invasive procedures.

    Knowing the precise needle-tip location is crucially important—and challenging. Ultrasound can help, but with the two-dimensional scans that are typically used, it can be unclear what part of the needle is in view, and the tip is often out of sight.

    And if the needle’s angle of insertion is steep, it will not be seen with ultrasound imaging. To address those limitations, Wenfeng Xia of University College London and his colleagues have installed a tiny fiber-optic ultrasound sensor with a Fabry–Pérot cavity into a surgical needle.

    The reflectance of the cavity is altered by impinging ultrasound waves, and it is measured continuously by a wavelength-tunable laser via the optical fiber in the needle’s cannula.

    During an ultrasound-guided procedure, transducer elements in the ultrasound probe generate pulses used both for imaging tissue and for sensing the tip. Because of the reversibility of the wave equation, the tip’s position can be inferred in real time from sensor data, knowledge of the positions of the transducers, and the time it takes their pulses to reach the tip.

    Last year Xia and his colleagues demonstrated the feasibility of their device on a live sheep fetus. In their newest paper, they report using pulse compression techniques borrowed from radar ranging to boost the accuracy of needle location by almost an order of magnitude

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    “Our mission

    The mission of Physics Today is to be a unifying influence for the diverse areas of physics and the physics-related sciences.

    It does that in three ways:

    • by providing authoritative, engaging coverage of physical science research and its applications without regard to disciplinary boundaries;
    • by providing authoritative, engaging coverage of the often complex interactions of the physical sciences with each other and with other spheres of human endeavor; and
    • by providing a forum for the exchange of ideas within the scientific community.”

     
  • richardmitnick 5:14 pm on June 20, 2016 Permalink | Reply
    Tags: , Joseph Conlon, Physics Today, ,   

    From Physics Today: “Questions and answers with Joseph Conlon” String Theory 

    Physics Today bloc

    Physics Today

    17 June 2016
    Jermey N. A. Matthews

    1
    Joseph Conlon. NO image credit.

    The apple didn’t fall far from the tree,” says University of Oxford theoretical physicist Joseph Conlon. The author of Why String Theory?, reviewed in this month’s issue of Physics Today, says that from an early age he was good at math—a critical skill for a string theorist—thanks to the influence of his father and uncle, both PhD mathematicians, and his mother, a physics teacher.

    2

    By age 18 Conlon had earned a bachelor’s degree in mathematics from the local University of Reading in the UK; he did it part-time, while still in secondary school. Conlon followed that up by obtaining his bachelor’s and PhD degrees in physics at the University of Cambridge. At Oxford, he now focuses on phenomenological applications of string theory to particle physics and cosmology. “One thing I certainly benefited from is that if you [pursue] a physics undergraduate degree, having already done a math undergraduate degree, then you don’t need to concentrate on the math; you can just concentrate on understanding the physics concepts,” says Conlon.

    For those who would question string theory’s validity because it can’t be experimentally tested, Conlon “presents a set of compelling arguments for the value of string theory while acknowledging its weaknesses and open challenges,” writes Gary Shiu in his Physics Today review. “Like courtroom juries, readers are encouraged to draw their own logical conclusions.” Conlon is also a cocreator of the public outreach website http://whystringtheory.com, which aims to be “a layman’s journey to the frontiers of physics.”

    Physics Today books editor Jermey Matthews and senior editor Steven Blau, a theoretical physicist by training, recently caught up with Conlon to discuss the book.

    PT: Why did you write the book?

    CONLON: It’s to answer the question I think lots of people are asking: Why are so many people working on string theory if this is something you can’t directly say is the true theory of the universe at the smallest possible scales?

    PT: So how would you answer the question “Why string theory?” for a nonexpert?

    CONLON: String theory has brought ideas and insights and results to so many different areas beyond its supposedly core area of quantum gravity. The analogy I use in the book is it’s like in a gold rush, you get rich by selling spades, rather than by finding nuggets. String theory has … been able to provide spades to lots of people across mathematics and theoretical physics in so many different topics. And this is why so many people are interested in it.

    PT: What inspired you to study string theory?

    CONLON: I guess it was a fairly natural thing for me to do, given my interests and inclinations at the time. When I was in Cambridge, I was training in particle theory, and I was trying to learn as much particle theory as I could. You take courses on quantum field theory, you take courses on the standard model, you take a course in string theory.

    The reason I wanted to carry on with the PhD in string theory was the feeling that lots of the standard model was carved out and understood in the 1970s and 1980s. String theory seemed more like something where I could get in and feel it wasn’t already done by the generation that came before.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth

    PT: Were you ever tempted by any of the other alternative approaches to quantum gravity like loop quantum gravity or dynamic causal histories?

    CONLON: Not really. I was never really exposed to them. As an undergraduate, it wasn’t something I learned or particularly had the option of learning then. And I haven’t been particularly tempted since then. From quite early on in my work on string theory I’ve been more interested in connecting it to experiments and observation. It’s great that people work on the formal problems of quantum gravity, but it’s not really my style of physics.

    PT: As you were writing the book, was there something that you were hoping to be able to convey but said, “this is just too tough a nut to crack”? Did you have to leave anything on the table?

    CONLON: Yes. There was a series of results around 1995 that were very important, involving D-branes. I ended up covering this less than I thought I would. And it partly was because I felt it was hard to try and convey to a general reader what was important about them without just dropping into buzz words.

    PT: And, conversely, is there anything that you were particularly proud you were able to get across in simple language?

    CONLON: I guess you have to ask the readers that. There are things I learned about—for example, the monstrous moonshine [a mathematical theory involving symmetries and related to conformal field theories] is a topic which I learned more about in the process of writing the book. I enjoyed writing about that because I learned about it at a slightly more technical level. It was a discovery process for me, too.

    PT: According to the Physics Today review, your book also touches on “the sociology of string theory.” Was that your intention?

    CONLON: Yes. Science is always more interesting when it’s done by humans, rather than [being] just abstract results. There’s also [a danger] you can get in if you look at someone very big [successful] and you say, “Gosh, they’ve gotten all these fantastic results. I can never possibly be like them. I’ll never be smart enough.”

    But people are good at different things. Even though you might not be able to get the results that person did, you’ve got skills that they don’t have. I tried to convey that there are many, many different ways of being a good theoretical physicist. And part of that was by talking about the sociology, the different types of people who do the subject and do it successfully.

    PT: Was explaining string theory to the general public a particular itch you wanted to scratch, or are you interested in writing other popular books?

    CONLON: A bit of both. I thought string theory was being misrepresented, particularly in the general press, that there was this [notion] that string theory primarily was a theory of quantum gravity. And so string theory would then … compete with other theories of quantum gravity. And this is something I wanted to argue against because most people who work on string theory don’t focus on quantum gravity. That was the itch I wanted to scratch.

    The book was also a chance to kind of let go the other side of my brain [used to write research papers] … and just write freely.

    PT: What is your next project?

    CONLON: In the process of finishing the book, basically I stopped doing research for six to nine months. So for the next two or three years I just want to do research because I enjoy doing research. And then I think I would like to write another book. I don’t know yet what it would be on.

    PT: What books are you currently reading?

    CONLON: I’ve got two on the go. The longer one, which I’m about halfway through, is [Winston] Churchill’s series The Second World War (Houghton Mifflin, ca. 1948–ca. 1953). And then the sort of more easy reading is one by Apollo astronaut (and physicist) Walter Cunningham, The All-American Boys: An Insider’s Look at the U.S. Space Program (revised edition, iPicturebooks, 2010).

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    “Our mission

    The mission of Physics Today is to be a unifying influence for the diverse areas of physics and the physics-related sciences.

    It does that in three ways:

    • by providing authoritative, engaging coverage of physical science research and its applications without regard to disciplinary boundaries;
    • by providing authoritative, engaging coverage of the often complex interactions of the physical sciences with each other and with other spheres of human endeavor; and
    • by providing a forum for the exchange of ideas within the scientific community.”

     
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