From Fermilab- “Frontier Science Result: MINERvA Scouting the party: neutrinos and nuclei”

Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

Friday, May 10, 2013
Philip Rodrigues

Neutrinos are notoriously difficult particles to study: For every 50 billion neutrinos that pass through the MINERvA detector at Fermilab, only about one will interact leaving a trace in our detector, producing particles that we can observe directly.

The likelihood of a neutrino undergoing a quasi-elastic interaction for different values of the momentum transferred to the proton or neutron (Q2) compared to several theoretical models. The data agree best with a model in which the neutrino can interact with multiple protons or neutrons at a time.

In spite of this, we are starting to use neutrinos to learn more about protons and neutrons and how they behave when they’re together inside an atomic nucleus. We already understand a lot about the nucleus: We know that it’s made of protons and neutrons, and we know the number of protons and the number of neutrons in the nucleus for every chemical element. But there is much we still don’t fully understand, especially about what those protons and neutrons are doing inside the nucleus.

We can study the protons’ and neutrons’ behavior in the nucleus the way we might study how people act at a party. Do the party-goers mingle according to the general spirit of the party, or do they break off into pairs? We could determine the party’s nature by sending in very shy folks and observing how quickly they leave and whether they leave through the same door they entered.

In a nucleus, does each proton and neutron react to just the average effect of the others, or do they occasionally pair up? One way to answer this question is to fire neutrinos at nuclei and measure the particles produced when neutrinos do interact with the nuclei of atoms in our detector. By studying those particles, we can try to infer the behavior of the protons and neutrons.”

The energy near the neutrino interaction point in neutrino quasi-elastic events. The data points, in black, are at higher energies on average than the prediction, in red, suggesting that the neutrino really is interacting with multiple protons or neutrons, which are kicked out of the nucleus.

See the full article here.

Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

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From DOE Pulse: “New particle detector records first 3-D tracks”

April 15, 2013
[Andre Salles, 630.840.3351,
media@fnal.gov]

“The NOvA particle detector, under construction in northern Minnesota, has begun recording its first three-dimensional images of particles. At its current size, the detector catches more than 1,000 cosmic rays per second. A webcam documents the progress of the construction of the humongous detector.

A cosmic-ray muon deposits a large shower of energy in the NOvA detector in Minnesota.

This summer, DOE’s Fermi National Accelerator Laboratory, located in Batavia, Ill., will start sending a beam of neutrinos every 1.3 seconds to the NOvA detector—500 miles straight through the Earth; no tunnel is necessary.

When complete in 2014, the full NOvA detector will be the most powerful neutrino detector in the United States. Made of PVC tubes that technicians will fill with scintillating liquid and outfit with light-sensitive electronics, the completed detector will weigh 14,000 tons. It will be the largest free-standing plastic structure in the world.

Scientists plan to use the NOvA experiment and Fermilab’s neutrino beam to discover the mass hierarchy of the three known types of neutrinos. Neutrinos are among the most abundant particles in the universe, but they have barely any mass and rarely interact with other matter particles. NOvA aims to discover which type of neutrino is the heaviest and which one is the lightest. The answer will shed light on the theoretical framework that scientists have proposed to describe neutrino interactions. Scientists suspect that neutrinos played a major role in the evolution of the universe. Neutrinos could help explain the imbalance of matter and antimatter in today’s universe, and scientists think there might be more types of neutrinos than the three known types.

‘The more we know about neutrinos, the more we know about the early universe and about how our world works at its most basic level,’ said NOvA co-spokesperson Gary Feldman of Harvard University.”

See the full article here.

DOE Pulse highlights work being done at the Department of Energy’s national laboratories. DOE’s laboratories house world-class facilities where more than 30,000 scientists and engineers perform cutting-edge research spanning DOE’s science, energy, National security and environmental quality missions. DOE Pulse is distributed twice each month.

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From Fermilab- “Frontier Science Result: MiniBooNE Stealthier than a neutrino”

Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

Friday, March 29, 2013
Zarko Pavlovic

“The search for sterile neutrinos has reached a new milestone. After collecting data for the past decade in both neutrino and antineutrino modes, the MiniBooNE experiment reports in a paper accepted for publication in Physical Review Letters an excess of events that suggests there may be additional neutrinos to the known three. MiniBooNE observed a combined excess of these events with 3.8 sigma significance.

MiniBooNE observes excesses of 78.4 ±20.0 (stat) ±20.3 (syst) and 162.0 ±28.1 (stat) ±38.7 (syst) candidate electron neutrino events in antineutrino (top) and neutrino (bottom) modes, respectively. Here they are given as a function of reconstructed neutrino energy. No credit.

It took 25 years to observe the electron neutrino after it was predicted to exist, so it is not surprising that it could take even longer to observe the proposed sterile partners of neutrinos. A sterile neutrino, unlike the neutrinos of the Standard Model, would not interact through the weak force. The existence of such neutrinos would be a sign of physics beyond the Standard Model.”

See the full article here.

Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

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From Symmetry Magazine: “OPERA snags third tau neutrino”

March 26, 2013
Kathryn Jepsen

“For the third time since the OPERA detector began receiving beam in 2006, the experiment has caught a muon neutrino oscillating into a tau neutrino.

For the third time ever, scientists have seen the particle transformation that explains the mystery of the ‘missing neutrinos’—particles we expect to rain down from the Sun and Earth’s atmosphere at higher rates than observed.

Neutrinos are light particles that come in three types, or flavors, each associated with a different subatomic particle: an electron, a muon or a tau. One of the biggest surprises that came with the discovery of neutrinos was that they could change from flavor to flavor.

Members of the OPERA experiment announced today the observation of a muon neutrino that had switched flavors to a tau neutrino. OPERA scientists, based at Gran Sasso National Laboratory in Italy, have caught this rare event only twice before, once in 2010 and once in 2012.

The new observation ‘is an important confirmation of the two previous observations,’ says Giovanni De Lellis, head of the international research team, in a statement released by INFN.

The OPERA experiment is a fast-moving, long-distance game of catch, with CERN laboratory at the border of France and Switzerland pitching a concentrated beam of neutrinos toward the 1,250-ton OPERA detector.

The beam of neutrinos from CERN is made up of muon neutrinos, the same kind of neutrinos created in the Sun. In the 1960s, physicists on multiple experiments found their counts of muon-flavored solar neutrinos were all coming in too low. It turned out that the solar neutrinos were there; they had just changed identities.

The OPERA experiment is the first neutrino experiment to examine a manmade beam of muon neutrinos in search of this type of oscillation. It will continue to take data for the next two years.

See the full article here.

The statement:

“26-03-2013: OPERA OBSERVED A THIRD NEUTRINO TAU

The OPERA international experiment at the INFN Gran Sasso Laboratory (Italy) has observed a third neutrino tau candidate from “flavour” oscillation. The “muon-type” neutrino produced at CERN in Geneva arrived at the Gran Sasso laboratory as a “tau” neutrino. An extremely rare event observed only twice before, in 2010 and in 2012. The OPERA international experiment (involving 140 physicists from 28 research institutes in 11 countries) was set up for the specific purpose of discovering this exceptionally rare event. Its observation confirms something scientists have been studying for more than 40 years: the fact that far fewer neutrinos seem to arrive from the Sun and the Earth atmosphere than expected. These “missing neutrinos” are indeed those that have oscillated into a different flavour.
The OPERA experiment was set up in 2001 for this specific purpose. A beam of neutrinos produced at CERN in Geneva travels towards the underground laboratory at the INFN Gran Sasso facility. Thanks to their extremely rare interactions with matter, after travelling through the earth for some 730 km the neutrinos arrive unperturbed at the giant OPERA detector (more than 4,000 tonnes, a volume of approx. 2,000 m3 and nine million photographic plates) where the minute quantity of particles that are caught are observed. In nature there are three kinds of neutrinos, termed “flavours”: electron, muon and tau. OPERA looks for the tau neutrinos knowing that all those leaving CERN are muon neutrinos. When neutrinos of another “flavour” are detected this is proof that oscillation occurs during the 730 km journey. After the first neutrinos arrived at the Gran Sasso laboratory in 2006, the experiment gathered data for five consecutive years, from 2008 to 2012. The first tau neutrino was observed in 2010, the second in 2012.
According to the head of the international research team, Giovanni De Lellis, from the Federico II University and INFN in Naples, the arrival of the third tau neutrino candidate “is an important confirmation of the two previous observations. This event has certain characteristics that make it entirely different from other processes. Statistically speaking too, the observation of three tau neutrino candidates provides the evidence of oscillations in the muon to tau neutrino channel in appearance mode. The data analysis will be pursued for two more years searching for other tau neutrinos that could definitely prove this very rare phenomenon.”

Symmetry is a joint Fermilab/SLAC publication.

From Fermilab- “Frontier Science Result: MINOS Does matter matter for neutrino flavor?”

Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

Friday, March 15, 2013
Zeynep Isvan, Brookhaven National Laboratory

“The NuMI (Neutrinos at the Main Injector) beam is generated here at Fermilab and points toward the Soudan Underground Laboratory in Soudan, Minn. The MINOS collaboration detects this beam of neutrinos in its journey twice: once at Fermilab right after it is generated and once at Soudan Lab after the neutrinos have traveled 450 miles through the Earth’s crust. At its generation, the beam is made up of muon-flavored neutrinos (neutrinos come in three flavors: electron, muon, and tau). After traveling such a long distance, some of the neutrinos change flavor, primarily into and a few into electron neutrinos. This phenomenon of flavor change is called neutrino oscillation. By counting the number (and measuring the energy) of muon neutrinos before and after travel, MINOS can measure parameters that govern neutrino oscillations.

By combining its neutrino and antineutrino data sets, MINOS has constrained the non-standard interaction parameter εμτ, finding that the results are consistent with εμτ=0, shown by the gray line. The angle θ and the parameter Δm2 relate to the relative masses of the neutrinos and to how quantum mechanically “mixed” the flavors are.

The presence of matter in the neutrino path may also have an impact on flavor change. If it does, the flavor count after travel would be altered. Some of these interactions are expected from the tiny number of oscillation-generated electron neutrinos, but extra interactions of muon or tau neutrinos with the Earth are non-standard and are thus called non-standard interactions, or NSI for short. (The Earth is made up of regular matter—electrons, protons and neutrons—and not of matter in muon or tau flavors.)

Because of its magnetized detectors, MINOS remains the most suitable experiment to further investigate NSI. Starting this spring, MINOS+ will collect data in a complementary energy regime. This will allow for a more precise determination of the impact of NSI in neutrino flavor change.”

See the full article here.

Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

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From Fermilab: “NOvA data concentrator modules near completion”

Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

Wednesday, Feb. 20, 2013
Leah Hesla

“News on Fermilab’s NOvA experiment has largely focused on the assembly of the enormous blocks that make up the football-field-sized particle detector in Minnesota. But elsewhere in the NOvA collaboration, engineers have been diligently plugging away at a more hidden-away part of the detector, a component without which the giant device would never be able to intelligibly reveal what it sees.

The NOvA data concentrator module collects and organizes all the particle interaction information generated inside the detector. Engineers are completing the design and testing of the system. Photo: Reidar Hahn

This crucial component is the circuitry and computer code that make up NOvA’s data concentrator modules, or DCMs. Now, after several years of design work and many months of testing and prototyping, engineers are completing the system. Nearly all that remains is for the modules to be installed onto the NOvA detector blocks as they, too, are installed.

‘Many people worked hard to develop a DCM system we expect to run very smoothly,’ said Fermilab’s Ron Rechenmacher, who led one of the DCM hardware-software integration efforts.

The NOvA DCM is a key component of the detector’s data acquisition system, which is responsible for collecting and organizing all the particle interaction information generated inside NOvA’s two detectors. When a particle interacts inside the detector, its energy is transmitted through the detector’s fiber optic system as light signals, which get converted to digital signals by electronics boards, travel through the DCMs and eventually make their way to the larger data acquisition system. The electronics boards and DCM together convert the signals into language that experimenters can later analyze.

NOvA’s DCM system comprises about 180 modules. Each of these custom modules, about the size of a briefcase, attaches to the detector. One hundred sixty-eight of them are assigned to NOvA’s far detector in Minnesota, and a dozen or so belong to the smaller near detector at Fermilab.”

See the full article here.

Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

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From Fermilab- “Frontier Science Result: MiniBooNE Nudging the community towards measuring where all the antimatter went”

Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

Friday, Feb. 15, 2013
Joe Grange

Joe Grange, University of Florida, performed the analysis for this MiniBooNE result.

“Like many of the processes we study at Fermilab, neutrino interactions probe fundamental properties of the universe. The focus of the MiniBooNE experiment has been to identify whether muon-type neutrinos spontaneously change into electron-type neutrinos in one of the neutrino beams created at the lab, possibly implying an extra neutrino state. However, recent work on the interactions of the muon-type neutrinos themselves has proven compelling as well, and this new result provides a first look at a specific muon antineutrino interaction.

This fundamental cross section shows the probability for a muon antineutrino to interact with a nucleon and produce a positively charged muon and any number of nucleons. For the first time, the MiniBooNE experiment has been able to split this measurement into a function of muon energy and scattering angle. By directly measuring the muon kinematics, these new data offer unprecedented insight into the behavior of the muon in antineutrino CCQE [(traditionally called a charged current quasi-elastic, or CCQE, interaction)]interactions. No image credit

In 2010, MiniBooNE released the first measurement of the cross section for muon-type neutrinos to elastically interact with a neutron to produce a muon and nucleons (traditionally called a charged current quasi-elastic, or CCQE, interaction) as a function of both muon energy and production angle relative to the incoming neutrino.

The new data presented here provides the world’s first look at how muon antineutrinos behave in similar reactions. Like the neutrino-based measurement of 2010, this antineutrino result also contributes to our knowledge of nuclear physics processes. Together, these measurements significantly advance the preparedness of the community to search for new physics with neutrinos.”

See the full article here. Follow the links for added information.

Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

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From Symmetry: “Long-baseline neutrino experiment”

The Long-Baseline Neutrino Experiment aims to discover whether neutrinos violate the fundamental matter–antimatter symmetry of physics.

February 13, 2013
Kurt Riesselmann

“The US Department of Energy has approved the conceptual design of a new experiment that will be a major test of our current understanding of neutrinos and their mysterious role in the universe. Scientists are now proceeding with the engineering design of the Long-Baseline Neutrino Experiment, which aims to discover whether neutrinos violate the fundamental matter–antimatter symmetry of physics. If they do, physicists will be a step closer to answering the puzzling question of why the universe is filled with matter while antimatter all but disappeared after the big bang.

So far, quarks are the only known particles that violate this fundamental symmetry. But the observed effect in quark interactions is not of the right kind to explain the abundance of matter over antimatter in our universe.

Scientists know that neutrino interactions also could violate matter–antimatter symmetry. If so, how strong is the effect? Scientists designed the LBNE experiment to discover the answer. They plan to break ground in 2015.

From around the world

The LBNE experiment will send beams of neutrinos and antineutrinos from the Department of Energy’s Fermilab, 40 miles west of Chicago, to the Sanford Lab in the Black Hills of South Dakota. More than 350 scientists and engineers from more than 60 institutions have joined the LBNE collaboration so far. They come from universities and national laboratories in the United States, India, Italy, Japan and the United Kingdom. The collaboration continues to grow, and project leaders seek and anticipate further international participation.

Start on the prairie

Surrounded by 1000 acres of tallgrass prairie, the accelerators at the Fermi National Accelerator Laboratory in Batavia, Illinois, will produce beams of muon neutrinos and antineutrinos for LBNE. Every 1.3 seconds, an accelerator will smash a batch of protons into a graphite target to make short-lived pions. Strong magnetic fields will guide and focus the pions to form a beam that points toward the LBNE detector in South Dakota. The pions will travel a few hundred feet, decay and produce muon neutrinos and antineutrinos.

A large particle detector to be built at the Sanford Lab will receive the neutrino and antineutrino beams. The lab is located at the former Homestake gold mine, the site of the Nobel Prize-winning Ray Davis solar neutrino experiment. The lab hosts several physics, biology, geology and engineering experiments, including investigations of neutrinos and dark matter. LBNE will be its largest experiment.”

See the full article here.

Symmetry is a joint Fermilab/SLAC publication.

From Fermilab “Frontier Science Result: MINOS Organizing the masses at MINOS”

Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

Friday, Jan. 18, 2013
Ryan Patterson, Caltech

“Over a decade ago the evidence became clear that neutrinos, which come in three varieties, can morph from one type to another as they travel, a phenomenon known as neutrino oscillation. By tallying how often this transformation happens under various conditions—different neutrino energies, different distances of travel—one can tease out a number of fundamental properties of neutrinos, for example, their relative masses. The MINOS collaboration has been doing exactly this by sending an intense beam of muon-type neutrinos from Fermilab to northern Minnesota, where a 5-kiloton detector lies in wait deep underground.

The 30 m long MINOS detector comprises 486 massive octagonal planes, lined up like the slices of a loaf of bread. Each plane consists of a sheet of steel that is about 8 m high and 2.5 cm thick, covered on one side with a layer of scintillating plastic. This photo shows the final plate in the assembly. (CERN)

MINOS also collected data with an antineutrino beam, and the real excitement comes in when combining the antineutrino and neutrino data sets. Differences between the rates of this particular oscillation mode between neutrinos and antineutrinos would point to a violation of something called CP symmetry. While physicists know that CP symmetry is violated by quarks, it remains unknown whether the same is true for neutrinos.

While further data will be needed to bring the answers into sharper focus, MINOS is the first to use this accelerator-based neutrino-antineutrino technique to probe such deep questions in the neutrino sector, paving the way for the next round of measurements.”

Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

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From Symmetry: “US-CERN partnership to accelerate neutrino research”

US institutions are working with the SHINE experiment at CERN to better understand the particle interactions that produce neutrinos.

December 19, 2012
Signe Brewster

“A new partnership between scientists from US institutions and CERN could improve results from neutrino experiments around the world. The scientists hope to use equipment at CERN to gain a more precise understanding of the process of creating a neutrino beam…”

NA61/SHINE detector layout
NA61/SHINE (SHINE = SPS Heavy Ion and Neutrino Experiment) is a particle physics experiment at the Super Proton Synchrotron (SPS) at (CERN)

Super Proton Synchrotron

The Super Proton Synchrotron is the second largest machine in CERN’s accelerator complex.

[Extra graphics added in to let the reader see the significance of the collaboration.]

“…Neutrinos are neutral in charge, so scientists cannot manipulate them with magnets in a particle accelerator. To create a neutrino beam, researchers accelerate positively charged protons and smash them into a fixed target made of beryllium or carbon. The resulting particle interactions produce pions and kaons, which also have charge. Physicists steer these particles into beams, at which point they decay into chargeless neutrinos.

Scientists from Fermilab, Los Alamos National Lab, University of Colorado, University of Pittsburgh and the College of William and Mary set out to sharpen their understanding of the initial interaction between the protons and the target. This will allow the collection of precise measurements for experiments such as Fermilab’s MINOS, MINERvA and the proposed Long-Baseline Neutrino Experiment, along with the T2K experiment in Japan.

The scientists discovered that they did not have to build a new experiment to make this type of measurement; it is already within the capabilities of another experiment at CERN. The SHINE experiment’s detector was designed to study strongly interacting matter, quark-gluon plasma and the production of composite particles. But it can also track and measure particles produced during the first step of the neutrino-beam-creation process: when protons collide with a fixed target. Researchers from the United States visited CERN this summer to try it out.

This isn’t the first time neutrino researchers based in the United States have partnered with experiments based at CERN, says Los Alamos physicist Geoffrey Mills, who organized the SHINE pilot run at CERN: ‘In 2002, a similar collaboration with the HARP experiment at CERN greatly enhanced Fermilab’s booster neutrino program.’”

HARP (The Hadron Production Experiment at the PS)

We should all hope that this collaboration is successful. See the full Symmetry article here.

Symmetry is a joint Fermilab/SLAC publication.

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