From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE): “New possibilities in the theoretical prediction of particle interactions”

From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE)

3.21.23
Professor Dr. Stefan Weinzierl
Theoretical High Energy Physics (THEP)
Institute of Physics and
PRISMA+ Cluster of Excellence
Johannes Gutenberg University Mainz
55099 Mainz
phone: +49 6131 39-25579

How does the world look like at the smallest scales? This is a question scientists are trying to answer in particle collider experiments like the Large Hadron Collider (LHC) at CERN in Switzerland.

The European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organization européenne pour la recherche nucléaire] [Europäische Organization für Kernforschung](CH) [CERN].

The European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organization européenne pour la recherche nucléaire] [Europäische Organization für Kernforschung](CH)[CERN] map. Credit: CERN.

CERN LHC tube in the tunnel. Credit: Maximilien Brice and Julien Marius Ordan.

The LHC magnets surround the beampipe along its 27 km circumference- Image CERN

SixTRack CERN LHC particles.

To compare the results of these experiments, theoretical physicists need to provide more and more precise predictions based on our current model for the interactions of fundamental particles, the so-called standard model. A key ingredient in these predictions are so called Feynman integrals. Recently, a team of the PRISMA+ Cluster of Excellence at Johannes Gutenberg University Mainz (JGU), consisting of Dr. Sebastian Pögel, Dr. Xing Wang and Prof. Dr. Stefan Weinzierl, developed a method to efficiently compute a new class of these Feynman integrals, associated to Calabi-Yau geometries. This research is now published in the renowned Physical Review Letters [below] and opens the path to high-precision theoretical predictions of particle interactions and to a better understanding of the elegant mathematical structure underpinning the world of particle physics.

“During the interaction of subatomic particles something special happens: Any number of additional particles can temporarily pop in and out of existence”, explained Professor Stefan Weinzierl. “When making theoretical predictions of such interactions, the more of these additional particles are taken into account, the more precise the computation will be to the real result.” Feynman integrals are mathematical objects which describe this effect, summing in effect all possible ways particles can appear and immediately disappear again.

Calabi-Yau geometries: An interplay of mathematics and physics

An important property determining the complexity of a Feynman integral is its geometry. Many of the simplest Feynman integrals have the geometry of a sphere or a torus, which is the mathematical term for a donut shape. Such integrals are nowadays well understood. However, there are entire families of geometries, so-called Calabi-Yau geometries, which are generalizations of the donut case to higher dimensions. These have proven to be a rich field of research in pure mathematics and have found extensive application in string theory in the last decades. In recent years, it was discovered that many Feynman integrals are associated to Calabi-Yau geometries, too. However, due to the complexity of the geometry, the efficient evaluation of such integrals has remained a challenge.

In their recent publication, Dr. Sebastian Pögel, Dr. Xing Wang, and Professor Stefan Weinzierl present a method that allows them to tackle integrals of Calabi-Yau geometries. They studied a simple family of Calabi-Yau Feynman integrals, so-called banana integrals.

Feynman graph of a banana intergral (ill./©: Weinzierl group)

The name is derived from the Feynman graph. Thereby they could find for the first time a so-called “epsilon-factorized form” for these integrals. This form allows to quickly evaluate the integral to nearly arbitrary precision, making them accessible for future experimental predictions predictions.

“It opens the door to a wide variety of hitherto unreachable Feynman integrals,” said Dr. Xing Wang. According to Dr. Sebastian Pögel, this is a nice example of how pure mathematics feeds into phenomenological predictions for high-energy experiments. “We are grateful to our colleagues in mathematics, and in particular to the group of Professor Duco van Straten, as we built on their work and now were able to achieve this exciting result”, Professor Stefan Weinzierl summarized.

Physical Review Letters

See the full article here.

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study.

The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany.

The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, The Goethe University Frankfurt(DE) and The Technische Universität Darmstadt(DE) together form the Rhine-Main-Universities [Rhein-Main Universitäten](DE)(RMU).

The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and Reichserzkanzler Adolf II von Nassau. At the time, establishing a university required papal approval and Adolf II initiated the approval process during his time in office. The university, however, was first opened in 1477 by Adolf’s successor to the bishopric, Diether von Isenburg. In 1784 the University was opened up for Protestants and Jews (curator Anselm Franz von Betzel). It fastly became one of the largest Catholic universities in Europe with ten chairs in theology alone. In the confusion after the establishment of the Mainz Republic of 1792 and its subsequent recapture by the Prussians, academic activity came to a gradual standstill. In 1798 the university became active again under French governance, and lectures in the department of medicine took place until 1823. Only the faculty of theology continued teaching during the 19th century, albeit as a theological Seminary (since 1877 “College of Philosophy and Theology”).

The current Johannes Gutenberg University Mainz was founded in 1946 by the French occupying power. In a decree on 1 March the French military government implied that the University of Mainz would continue to exist: the University shall be “enabled to resume its function”. The remains of anti-aircraft warfare barracks erected in 1938 after the remilitarization of the Rhineland during the Third Reich served as the university’s first buildings and are still in use today.

The continuation of academic activity between the old university and Johannes Gutenberg University Mainz, in spite of an interruption spanning over 100 years, is contested. During the time up to its reopening only a seminary and midwifery college survived.

In 1972, the effect of the 1968 student protests began to take a toll on the University’s structure. The departments (Fakultäten) were dismantled and the University was organized into broad fields of study (Fachbereiche). Finally in 1974 Peter Schneider was elected as the first president of what was now a “constituted group-university” institute of higher education. In 1990 Jürgen Zöllner became University President yet spent only a year in the position after he was appointed Minister for “Science and Advanced Education” for the State of Rhineland-Palatinate. As the coordinator for the SPD’s higher education policy, this furloughed professor from the Institute for Physiological Chemistry played a decisive role in the SPD’s higher education policy and in the development of Study Accounts.

From The University of Michigan And The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE): “A new model for dark matter”

From The University of Michigan

And

The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE)

1.23.23
Bernie DeGroat
734-647-1847
bernied@umich.edu

Phase transition in early universe changes strength of interaction between dark and normal matter.

This NASA Hubble Space Telescope image shows the distribution of dark matter in the center of the giant galaxy cluster Abell 1689, containing about 1,000 galaxies and trillions of stars. Dark matter is an invisible form of matter that accounts for most of the universe’s mass. Hubble cannot see the dark matter directly. Astronomers inferred its location by analyzing the effect of gravitational lensing, where light from galaxies behind Abell 1689 is distorted by intervening matter within the cluster.

Gravitational Lensing National Aeronautics Space Agency and European Space Agency [La Agencia Espacial Europea][Agence spatiale européenne][Europäische Weltraumorganization](EU).

Researchers used the observed positions of 135 lensed images of 42 background galaxies to calculate the location and amount of dark matter in the cluster. They superimposed a map of these inferred dark matter concentrations, tinted blue, on an image of the cluster taken by Hubble’s Advanced Camera for Surveys.

National Aeronautics Space Agency/European Space Agency [La Agencia Espacial Europea][Agence spatiale européenne][Europäische Weltraumorganization](EU) Advanced Camera for Surveys (ACS) on the NASA/ESA Hubble Space Telescope.

If the cluster’s gravity came only from the visible galaxies, the lensing distortions would be much weaker. The map reveals that the densest concentration of dark matter is in the cluster’s core. Abell 1689 resides 2.2 billion light-years from Earth. The image was taken in June 2002. Image credit: D. Coe (NASA Jet Propulsion Laboratory/California Institute of Technology, and Space Telescope Science Institute) NASA/ESA; , N. Benitez (Institute of Astrophysics of Andalusia, Spain), T. Broadhurst (University of the Basque Country, Spain), and H. Ford (Johns Hopkins University).

Dark matter remains one of the greatest mysteries of modern physics. It is clear that it must exist, because without dark matter, for example, the motion of galaxies cannot be explained. But it has never been possible to detect dark matter in an experiment.

Currently, there are many proposals for new experiments: They aim to detect dark matter directly via its scattering from the constituents of the atomic nuclei of a detection medium, i.e., protons and neutrons.

A team of researchers—Robert McGehee and Aaron Pierce of the University of Michigan and Gilly Elor of Johannes Gutenberg University of Mainz in Germany—has now proposed a new candidate for dark matter-“HYPER”: “HighlY Interactive ParticlE Relics.”

In the HYPER model some time after the formation of dark matter in the early universe the strength of its interaction with normal matter increases abruptly—which on the one hand makes it potentially detectable today and at the same time can explain the abundance of dark matter.

The new diversity in the dark matter sector

Since the search for heavy dark matter particles, or so-called WIMPS, has not yet led to success, the research community is looking for alternative dark matter particles, especially lighter ones. At the same time, one generically expects phase transitions in the dark sector—after all, there are several in the visible sector, the researchers say. But previous studies have tended to neglect them.

“There has not been a consistent dark matter model for the mass range that some planned experiments hope to access. “However, our HYPER model illustrates that a phase transition can actually help make the dark matter more easily detectable,” said Elor, a postdoctoral researcher in theoretical physics at JGU.

The challenge for a suitable model: If dark matter interacts too strongly with normal matter, its (precisely known) amount formed in the early universe would be too small, contradicting astrophysical observations. However, if it is produced in just the right amount, the interaction would conversely be too weak to detect dark matter in present-day experiments.

“Our central idea, which underlies the HYPER model, is that the interaction changes abruptly once—so we can have the best of both worlds: the right amount of dark matter and a large interaction so we might detect it,” McGehee said.

Constraints in the mediator mass-nucleon coupling plane from cooling of HB stars [25] and SN 1987A [12], as well as rare kaon decays [26] (gray shading). Credit: Physical Review Letters (2023).

And this is how the researchers envision it: In particle physics an interaction is usually mediated by a specific particle, a so-called mediator—and so is the interaction of dark matter with normal matter. Both the formation of dark matter and its detection function via this mediator, with the strength of the interaction depending on its mass: The larger the mass, the weaker the interaction.

The mediator must first be heavy enough so that the correct amount of dark matter is formed and later light enough so that dark matter is detectable at all. The solution: There was a phase transition after the formation of dark matter, during which the mass of the mediator suddenly decreased.

“Thus, on the one hand, the amount of dark matter is kept constant, and on the other hand, the interaction is boosted or strengthened in such a way that dark matter should be directly detectable,” Pierce said.

New model covers almost the full parameter range of planned experiments

“The HYPER model of dark matter is able to cover almost the entire range that the new experiments make accessible,” Elor said.

Specifically, the research team first considered the maximum cross section of the mediator-mediated interaction with the protons and neutrons of an atomic nucleus to be consistent with astrological observations and certain particle-physics decays. The next step was to consider whether there was a model for dark matter that exhibited this interaction.

“And here we came up with the idea of the phase transition,” McGehee said. “We then calculated the amount of dark matter that exists in the universe and then simulated the phase transition using our calculations.”

There are a great many constraints to consider, such as a constant amount of dark matter.

“Here, we have to systematically consider and include very many scenarios, for example, asking the question whether it is really certain that our mediator does not suddenly lead to the formation of new dark matter, which of course must not be,” Elor said. “But in the end, we were convinced that our HYPER model works.”

The research is published in the journal Physical Review Letters.
__________________________________
Dark Matter Background
Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., and Vera Rubin a Woman in STEM, denied the Nobel, some 30 years later, did most of the work on Dark Matter.

Fritz Zwicky.

Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.

In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

Vera Rubin measuring spectra, worked on Dark Matter(Emilio Segre Visual Archives AIP SPL).

Dark Matter Research

Super Cryogenic Dark Matter Search from DOE’s SLAC National Accelerator Laboratory at Stanford University at SNOLAB (Vale Inco Mine, Sudbury, Canada).

LBNL LZ Dark Matter Experiment xenon detector at Sanford Underground Research Facility Credit: Matt Kapust.

Lambda Cold Dark Matter Expansion ΛCDM of the Universe. Credit Alex Mittelmann Coldcreation.

DAMA at Gran Sasso uses sodium iodide housed in copper to hunt for dark matter LNGS-INFN.

Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB (CA) deep in Sudbury’s Creighton Mine.

The LBNL LZ Dark Matter Experiment Dark Matter project at SURF, Lead, SD.

DAMA-LIBRA Dark Matter experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) located in the Abruzzo region of central Italy.

DARWIN Dark Matter experiment. A design study for a next-generation, multi-ton dark matter detector in Europe at The University of Zurich [Universität Zürich](CH).

PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China.

Inside the Axion Dark Matter eXperiment U Washington. Credit: Mark Stone U. of Washington. Axion Dark Matter Experiment.

XENONnT experiment at the Laboratori Nazionali del Gran Sasso (LNGS) underground laboratory in Italy.

The University of Western Australia ORGAN Experiment’s main detector. A small copper cylinder called a “resonant cavity” traps photons generated during dark matter conversion. The cylinder is bolted to a “dilution refrigerator” which cools the experiment to very low temperatures.
__________________________________

See the full article here .

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.

five-ways-keep-your-child-safe-school-shootings

Please support STEM education in your local school system

Stem Education Coalition

The The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study.

The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany.

The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, The Goethe University Frankfurt(DE) and The Technische Universität Darmstadt(DE) together form the Rhine-Main-Universities [Rhein-Main Universitäten](DE)(RMU).

The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and Reichserzkanzler Adolf II von Nassau. At the time, establishing a university required papal approval and Adolf II initiated the approval process during his time in office. The university, however, was first opened in 1477 by Adolf’s successor to the bishopric, Diether von Isenburg. In 1784 the University was opened up for Protestants and Jews (curator Anselm Franz von Betzel). It fastly became one of the largest Catholic universities in Europe with ten chairs in theology alone. In the confusion after the establishment of the Mainz Republic of 1792 and its subsequent recapture by the Prussians, academic activity came to a gradual standstill. In 1798 the university became active again under French governance, and lectures in the department of medicine took place until 1823. Only the faculty of theology continued teaching during the 19th century, albeit as a theological Seminary (since 1877 “College of Philosophy and Theology”).

The current Johannes Gutenberg University Mainz was founded in 1946 by the French occupying power. In a decree on 1 March the French military government implied that the University of Mainz would continue to exist: the University shall be “enabled to resume its function”. The remains of anti-aircraft warfare barracks erected in 1938 after the remilitarization of the Rhineland during the Third Reich served as the university’s first buildings and are still in use today.

The continuation of academic activity between the old university and Johannes Gutenberg University Mainz, in spite of an interruption spanning over 100 years, is contested. During the time up to its reopening only a seminary and midwifery college survived.

In 1972, the effect of the 1968 student protests began to take a toll on the University’s structure. The departments (Fakultäten) were dismantled and the University was organized into broad fields of study (Fachbereiche). Finally in 1974 Peter Schneider was elected as the first president of what was now a “constituted group-university” institute of higher education. In 1990 Jürgen Zöllner became University President yet spent only a year in the position after he was appointed Minister for “Science and Advanced Education” for the State of Rhineland-Palatinate. As the coordinator for the SPD’s higher education policy, this furloughed professor from the Institute for Physiological Chemistry played a decisive role in the SPD’s higher education policy and in the development of Study Accounts.

The University of Michigan is a public research university located in Ann Arbor, Michigan, United States. Originally, founded in 1817 in Detroit as the Catholepistemiad, or University of Michigania, 20 years before the Michigan Territory officially became a state, the University of Michigan is the state’s oldest university. The university moved to Ann Arbor in 1837 onto 40 acres (16 ha) of what is now known as Central Campus. Since its establishment in Ann Arbor, the university campus has expanded to include more than 584 major buildings with a combined area of more than 34 million gross square feet (781 acres or 3.16 km²), and has two satellite campuses located in Flint and Dearborn. The University was one of the founding members of the Association of American Universities.

Considered one of the foremost research universities in the United States, the university has very high research activity and its comprehensive graduate program offers doctoral degrees in the humanities, social sciences, and STEM fields (Science, Technology, Engineering and Mathematics) as well as professional degrees in business, medicine, law, pharmacy, nursing, social work and dentistry. Michigan’s body of living alumni (as of 2012) comprises more than 500,000. Besides academic life, Michigan’s athletic teams compete in Division I of the NCAA and are collectively known as the Wolverines. They are members of the Big Ten Conference.

At over $12.4 billion in 2019, Michigan’s endowment is among the largest of any university. As of October 2019, 53 MacArthur “genius award” winners (29 alumni winners and 24 faculty winners), 26 Nobel Prize winners, six Turing Award winners, one Fields Medalist and one Mitchell Scholar have been affiliated with the university. Its alumni include eight heads of state or government, including President of the United States Gerald Ford; 38 cabinet-level officials; and 26 living billionaires. It also has many alumni who are Fulbright Scholars and MacArthur Fellows.

Research

Michigan is one of the founding members (in the year 1900) of the Association of American Universities. With over 6,200 faculty members, 73 of whom are members of the National Academy and 471 of whom hold an endowed chair in their discipline, the university manages one of the largest annual collegiate research budgets of any university in the United States. According to the National Science Foundation, Michigan spent $1.6 billion on research and development in 2018, ranking it 2nd in the nation. This figure totaled over $1 billion in 2009. The Medical School spent the most at over $445 million, while the College of Engineering was second at more than $160 million. U-M also has a technology transfer office, which is the university conduit between laboratory research and corporate commercialization interests.

In 2009, the university signed an agreement to purchase a facility formerly owned by Pfizer. The acquisition includes over 170 acres (0.69 km^2) of property, and 30 major buildings comprising roughly 1,600,000 square feet (150,000 m^2) of wet laboratory space, and 400,000 square feet (37,000 m^2) of administrative space. At the time of the agreement, the university’s intentions for the space were not set, but the expectation was that the new space would allow the university to ramp up its research and ultimately employ in excess of 2,000 people.

The university is also a major contributor to the medical field with the EKG and the gastroscope. The university’s 13,000-acre (53 km^2) biological station in the Northern Lower Peninsula of Michigan is one of only 47 Biosphere Reserves in the United States.

In the mid-1960s U-M researchers worked with IBM to develop a new virtual memory architectural model that became part of IBM’s Model 360/67 mainframe computer (the 360/67 was initially dubbed the 360/65M where the “M” stood for Michigan). The Michigan Terminal System (MTS), an early time-sharing computer operating system developed at U-M, was the first system outside of IBM to use the 360/67’s virtual memory features.

U-M is home to the National Election Studies and the University of Michigan Consumer Sentiment Index. The Correlates of War project, also located at U-M, is an accumulation of scientific knowledge about war. The university is also home to major research centers in optics, reconfigurable manufacturing systems, wireless integrated microsystems, and social sciences. The University of Michigan Transportation Research Institute and the Life Sciences Institute are located at the university. The Institute for Social Research (ISR), the nation’s longest-standing laboratory for interdisciplinary research in the social sciences, is home to the Survey Research Center, Research Center for Group Dynamics, Center for Political Studies, Population Studies Center, and Inter-Consortium for Political and Social Research. Undergraduate students are able to participate in various research projects through the Undergraduate Research Opportunity Program (UROP) as well as the UROP/Creative-Programs.

The U-M library system comprises nineteen individual libraries with twenty-four separate collections—roughly 13.3 million volumes. U-M was the original home of the JSTOR database, which contains about 750,000 digitized pages from the entire pre-1990 backfile of ten journals of history and economics, and has initiated a book digitization program in collaboration with Google. The University of Michigan Press is also a part of the U-M library system.

In the late 1960s U-M, together with Michigan State University and Wayne State University, founded the Merit Network, one of the first university computer networks. The Merit Network was then and remains today administratively hosted by U-M. Another major contribution took place in 1987 when a proposal submitted by the Merit Network together with its partners IBM, MCI, and the State of Michigan won a national competition to upgrade and expand the National Science Foundation Network (NSFNET) backbone from 56,000 to 1.5 million, and later to 45 million bits per second. In 2006, U-M joined with Michigan State University and Wayne State University to create the the University Research Corridor. This effort was undertaken to highlight the capabilities of the state’s three leading research institutions and drive the transformation of Michigan’s economy. The three universities are electronically interconnected via the Michigan LambdaRail (MiLR, pronounced ‘MY-lar’), a high-speed data network providing 10 Gbit/s connections between the three university campuses and other national and international network connection points in Chicago.

From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE): “Mainz team of scientists provides insight into the diffuse ice of Antarctica”

From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE)

10.21.22

Since 2010, the IceCube Neutrino Observatory at the South Pole has been searching for high-energy neutrinos from space. The experiment consists of 5,160 optical sensors, the so-called digital optical modules (DOMs), which are sunk up to 2.5 kilometers deep in one cubic kilometer of Antarctic ice.
_____________________________________________________
U Wisconsin IceCube Neutrino Observatory

U Wisconsin IceCube Neutrino Observatory neutrino detector at the at the Amundsen-Scott South Pole Station in Antarctica South Pole, elevation of 2,835 metres (9,301 feet).
IceCube employs more than 5000 detectors lowered on 86 strings into almost 100 holes in the Antarctic ice NSF B. Gudbjartsson, IceCube Collaboration.

Lunar Icecube

IceCube Gen-2 DeepCore PINGU annotated

IceCube neutrino detector interior.

IceCube DeepCore annotated.

DM-Ice II at IceCube annotated.

_____________________________________________________

When a neutrino interacts with a molecule in the ice, characteristic blue Čerenkov light is produced. This travels through the ice and can reach some of the DOMs where it is detected. The researchers can then reconstruct the energy and direction of the original neutrino – a process based on knowledge of the optical properties of the ice. In 2013, the IceCube collaboration reported a unique observation in which the brightness of a light source in the ice depends on the direction of the light from which it is observed. So far, researchers have tried to describe this so-called anisotropy with variations in the absorption and scattering caused by impurities, but so far with limited success.

In a recent study published in the journal The Cryosphere Discussions [below], the IceCube collaboration reports a new optical effect for the first time. It is the result of the birefringent properties of elongated ice crystals. The newly gained insights have been incorporated into a new birefringence-based optical model of the ice, which has significantly improved the interpretation of the light patterns resulting from particle interactions in the ice.

©: Jack Pairin / IceCube Collaboration
Without birefringence (top), the light flows radially from an isotropic light source. With birefringence (bottom), the light is slowly deflected towards the ice flow axis.

To improve previous attempts to simulate anisotropy, the researchers studied the anisotropy effect in more detail. Their results led them to believe that the many randomly arranged small crystals that make up the ice, and not just impurities it contains, play a role in the observed anisotropy.

“Then we realized that assuming curved light paths with tiny deflections of less than one degree per meter, we can suddenly accurately describe the IceCube data. This really got things rolling,” says Dr. Martin Rongen, researcher at the PRISMA Cluster of Excellence.+ Johannes Gutenberg University Mainz (JGU) and is in charge of the current analysis. “The next question was: How does this curvature come about? The answer lies in the microstructure of the ice: indeed, when calculating and simulating the light scattering by birefringent polycrystalline ice, as occurs in IceCube and where the crystals are stretched on average along the direction of flow of the ice, such a deflection results.”

For the study, the researchers simulated many different paths that light could travel within the IceCube detector – based on thousands of different crystal configurations in the ice. They then compared the simulated data with a large calibration data set. This includes data from 60,000 LEDs attached to all DOMs that emit consistent light pulses into the ice. From the comparison, the researchers were able to draw conclusions about the average shape and size of the ice crystals in IceCube.

In order to use this new discovery in the study of cosmic neutrinos, the IceCube collaboration created new simulations and adapted the current reconstruction methods. This new understanding will not only help IceCube to better reconstruct neutrino interactions, but also has implications for the field of glaciology.

“I am fascinated by the idea of understanding ice from the ground up,” says Dr. Martin Rongen. “Ice crystal properties are investigated in particular in order to understand the mechanics of ice flow. This in turn is the basis for predicting the Antarctic mass balance and the resulting rise in sea level in a changing climate.”

Science paper:
The Cryosphere Discussions

See the full article here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study.

The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany.

The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, The Goethe University Frankfurt(DE) and The Technische Universität Darmstadt(DE) together form the Rhine-Main-Universities [Rhein-Main Universitäten](DE)(RMU).

The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and Reichserzkanzler Adolf II von Nassau. At the time, establishing a university required papal approval and Adolf II initiated the approval process during his time in office. The university, however, was first opened in 1477 by Adolf’s successor to the bishopric, Diether von Isenburg. In 1784 the University was opened up for Protestants and Jews (curator Anselm Franz von Betzel). It fastly became one of the largest Catholic universities in Europe with ten chairs in theology alone. In the confusion after the establishment of the Mainz Republic of 1792 and its subsequent recapture by the Prussians, academic activity came to a gradual standstill. In 1798 the university became active again under French governance, and lectures in the department of medicine took place until 1823. Only the faculty of theology continued teaching during the 19th century, albeit as a theological Seminary (since 1877 “College of Philosophy and Theology”).

The current Johannes Gutenberg University Mainz was founded in 1946 by the French occupying power. In a decree on 1 March the French military government implied that the University of Mainz would continue to exist: the University shall be “enabled to resume its function”. The remains of anti-aircraft warfare barracks erected in 1938 after the remilitarization of the Rhineland during the Third Reich served as the university’s first buildings and are still in use today.

The continuation of academic activity between the old university and Johannes Gutenberg University Mainz, in spite of an interruption spanning over 100 years, is contested. During the time up to its reopening only a seminary and midwifery college survived.

In 1972, the effect of the 1968 student protests began to take a toll on the University’s structure. The departments (Fakultäten) were dismantled and the University was organized into broad fields of study (Fachbereiche). Finally in 1974 Peter Schneider was elected as the first president of what was now a “constituted group-university” institute of higher education. In 1990 Jürgen Zöllner became University President yet spent only a year in the position after he was appointed Minister for “Science and Advanced Education” for the State of Rhineland-Palatinate. As the coordinator for the SPD’s higher education policy, this furloughed professor from the Institute for Physiological Chemistry played a decisive role in the SPD’s higher education policy and in the development of Study Accounts.

From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE): “The conundrum of the anomalous magnetic moment of the muon”

From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE)

10.21.22
Professor Dr. Hartmut Wittig
Institute for Nuclear Physics
and
PRISMA+ Cluster of Excellence
Johannes Gutenberg University Mainz
55099 Mainz
Tel.: +49 6131 39-26808
Fax: +49 6131 39-27079
hartmut.wittig@uni-mainz.de

New calculations based on fundamental theories deviate from the currently accepted theoretical value.

The anomalous magnetic moment of the muon is a crucial parameter in particle physics as it allows for precision tests of the established Standard Model. A new measurement of this quantity in 2021 caused a furor as it reaffirmed a significant deviation from the theoretical prediction – in other words, the anomalous magnetic moment is greater than anticipated.

Physicists calculate the theoretical prediction on the basis of the currently valid Standard Model of particle physics. In 2020, the Muon g-2 Theory Initiative – a group of 130 physicists with a strong representation from Mainz – produced a consensual estimate that has since been accepted as the reference value. Since then, several teams, including that of Professor Hartmut Wittig of the PRISMA+ Cluster of Excellence at Johannes Gutenberg University Mainz (JGU), have published new results* for the contribution from the strong interaction using numerical simulations of lattice QCD, which suggest that the theoretical prediction is moving towards the experimental value. “Even if it turns out that the deviation between the theoretical and experiment results is actually smaller than we thought, this would still represent a major divergence,” said Wittig. “But it is still imperative for us to first understand why the use of differing theoretical methods leads to such dissimilar results.”

*See the science paper for instructive material with images.

A new mystery that requires a solution

The anomalous magnetic moment receives contributions from all fundamental interactions except gravity. The strong interaction or strong nuclear force which acts between the elementary particles of matter known as quarks and which is mediated by the exchange of gluons is of particular importance when it comes to testing the Standard Model. Recent calculations have focused on the so-called hadronic vacuum polarization (HVP) contribution to the muon magnetic moment, in which quark-antiquark pairs are continually generated from a vacuum for a split second before disappearing again. “This is an extremely complex process to handle, and the level of uncertainty of the theoretical prediction is thus largely determined by the effects of the strong interaction,” added Wittig. As the standard computational techniques either cannot be used in this context or have to date not been precise enough, in the current consensus paper the HVP contribution was determined by employing experimental data at various particle accelerators.

It would be ideal if the HVP contribution could be calculated without relying on experimental data, using Quantum Chromodynamics (QCD) alone. QCD is the fundamental theory of the strong interaction between quarks mediated by gluons. However, QCD is an extremely difficult theory to handle in practice. The Mainz team uses a technique known as lattice field theory for this purpose. Here the quarks and gluons are distributed over a discrete grid of points that represent space-time, very much like atoms in a crystal. The HVP contribution to the anomalous magnetic moment of the muon can then be determined with the help of supercomputers.

JGU high-performance computer MOGON II

“Until just a few years ago, the huge technical challenges of such a calculation made it impossible to determine the HVP contribution with the necessary accuracy using lattice QCD. In the meantime we have refined the method so that the precision of our result can match that of the traditional approach that resorts to using experimental data,” said Professor Hartmut Wittig. In the newly published paper, Wittig and his team present the results of calculation of a fraction of HVP that is particularly suitable for testing the consistency of the results of various lattice calculations and comparing these with the estimates based on the traditional method. “As our result is just as precise, you could say that lattice QCD calculation has passed its baptism of fire, which in itself is a huge success. Moreover, it is becoming increasingly clear that our QCD-based calculations actually correspond with the newly presented results of other teams.”

Wittig now turns his attention back to the magnetic moment of the muon: “Our new lattice calculations are making it more apparent that the theoretical prediction value is likely to move closer to the measured result. This has generated quite a bit of excitement among my colleagues. We are now focusing on the problem of why different methods used to evaluate the HVP contribution should produce discrepant results. And those of our colleagues who may be disappointed that the discrepancy with the Standard Model is shrinking can take comfort in the fact that our new calculation has not made the deviation between theory and experiment go away completely. Whichever way you look at it, there is no doubt that there is a discrepancy that requires explanation. There is still a lot we need to understand.”

See the full article here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study.

The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany.

The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, The Goethe University Frankfurt(DE) and The Technische Universität Darmstadt(DE) together form the Rhine-Main-Universities [Rhein-Main Universitäten](DE)(RMU).

The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and Reichserzkanzler Adolf II von Nassau. At the time, establishing a university required papal approval and Adolf II initiated the approval process during his time in office. The university, however, was first opened in 1477 by Adolf’s successor to the bishopric, Diether von Isenburg. In 1784 the University was opened up for Protestants and Jews (curator Anselm Franz von Betzel). It fastly became one of the largest Catholic universities in Europe with ten chairs in theology alone. In the confusion after the establishment of the Mainz Republic of 1792 and its subsequent recapture by the Prussians, academic activity came to a gradual standstill. In 1798 the university became active again under French governance, and lectures in the department of medicine took place until 1823. Only the faculty of theology continued teaching during the 19th century, albeit as a theological Seminary (since 1877 “College of Philosophy and Theology”).

The current Johannes Gutenberg University Mainz was founded in 1946 by the French occupying power. In a decree on 1 March the French military government implied that the University of Mainz would continue to exist: the University shall be “enabled to resume its function”. The remains of anti-aircraft warfare barracks erected in 1938 after the remilitarization of the Rhineland during the Third Reich served as the university’s first buildings and are still in use today.

The continuation of academic activity between the old university and Johannes Gutenberg University Mainz, in spite of an interruption spanning over 100 years, is contested. During the time up to its reopening only a seminary and midwifery college survived.

In 1972, the effect of the 1968 student protests began to take a toll on the University’s structure. The departments (Fakultäten) were dismantled and the University was organized into broad fields of study (Fachbereiche). Finally in 1974 Peter Schneider was elected as the first president of what was now a “constituted group-university” institute of higher education. In 1990 Jürgen Zöllner became University President yet spent only a year in the position after he was appointed Minister for “Science and Advanced Education” for the State of Rhineland-Palatinate. As the coordinator for the SPD’s higher education policy, this furloughed professor from the Institute for Physiological Chemistry played a decisive role in the SPD’s higher education policy and in the development of Study Accounts.

From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE): “Worldwide coordinated search for dark matter”

From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE)

20 January 2022

Professor Dr. Dmitry Budker
Quantum, Atomic, and Neutron Physics (QUANTUM)
Institute of Physics
Johannes Gutenberg University Mainz
and
PRISMA+ Cluster of Excellence
and
Helmholtz Institute – Mainz [Helmholtz-Institut Mainz](DE)
55099 Mainz
Tel.: +49 6131 39-27414
budker@uni-mainz.de

An international team of researchers with key participation from the PRISMA+ Cluster of Excellence at Johannes Gutenberg University Mainz (JGU) and The Helmholtz Institute – Mainz [Helmholtz-Institut Mainz](DE) has published for the first time comprehensive data on the search for dark matter using a worldwide network of optical magnetometers.

Sketch of the worldwide GNOME network. ©: Hector Masia Roig.

Mainz-based setup of the GNOME Network. Photo: Hector Masia Roig.

According to the scientists, Dark Matter fields should produce a characteristic signal pattern that can be detected by correlated measurements at multiple stations of the GNOME network. Analysis of data from a one-month continuous GNOME operation has not yet yielded a corresponding indication. However, the measurement allows to formulate constraints on the characteristics of Dark Matter, as the researchers report in the prestigious journal Nature Physics.

GNOME stands for Global Network of Optical Magnetometers for Exotic Physics Searches. Behind it are magnetometers distributed around the world in Germany, Serbia, Poland, Israel, South Korea, China, Australia, and the United States. With GNOME, the researchers particularly want to advance the search for Dark Matter – one of the most exciting challenges of fundamental physics in the 21st century. After all, it has long been known that many puzzling astronomical observations, such as the rotation speed of stars in galaxies or the spectrum of the cosmic background radiation, can best be explained by Dark Matter.

“Extremely light bosonic particles are considered one of the most promising candidates for Dark Matter today. These include so-called axion-like particles – ALPs for short,” said Professor Dr. Dmitry Budker, professor at PRISMA+ and at HIM, an institutional collaboration of Johannes Gutenberg University Mainz and The GSI Helmholtz Centre for Heavy Ion Research [GSI Helmholtzzentrum für Schwerionenforschung-Darmstadt](DE). “They can also be considered as a classical field oscillating with a certain frequency. A peculiarity of such bosonic fields is that – according to a possible theoretical scenario – they can form patterns and structures. As a result, the density of Dark Matter could be concentrated in many different regions – discrete domain walls smaller than a galaxy but much larger than Earth could form, for example.”

“If such a wall encounters the Earth, it is gradually detected by the GNOME network and can cause transient characteristic signal patterns in the magnetometers,” explained Dr. Arne Wickenbrock, one of the study’s co-authors. “Even more, the signals are correlated with each other in certain ways – depending on how fast the wall is moving and when it reaches each location.”

The network meanwhile consists of 14 magnetometers distributed over eight countries worldwide-nine of them provided data for the current analysis. The measurement principle is based on an interaction of dark matter with the nuclear spins of the atoms in the magnetometer. The atoms are excited with a laser at a specific frequency, orienting the nuclear spins in one direction. A potential dark matter field can disturb this direction, which is measurable.

Figuratively speaking, one can imagine that the atoms in the magnetometer initially dance around in confusion, as clarified by Hector Masia-Roig, a doctoral student in the Budker group and also an author of the current study. “When they “hear” the right frequency of laser light, they all spin together. Dark Matter particles can throw the dancing atoms out of balance. We can measure this perturbation very precisely.” Now the network of magnetometers becomes important: When the Earth moves through a spatially limited wall of Dark Matter, the dancing atoms in all stations are gradually disturbed. One of these stations is located in a laboratory at the Helmholtz Institute in Mainz. “Only when we match the signals from all the stations can we assess what triggered the disturbance,”said Masia-Roig. “Applied to the image of the dancing atoms, this means: If we compare the measurement results from all the stations, we can decide whether it was just one brave dancer dancing out of line or actually a global dark matter disturbance.”

In the current study, the research team analyzes data from a one-month continuous operation of GNOME. The result: Statistically significant signals did not appear in the investigated mass range from one femtoelectronvolt (feV) to 100,000 feV. Conversely, this means that the researchers can narrow down the range in which such signals could theoretically be found even further than before. For scenarios that rely on discrete Dark Matter walls, this is an important result – “even though we have not yet been able to detect such a domain wall with our global ring search,” added Joseph Smiga, another PhD student in Mainz and author of the study.

Future work of the GNOME collaboration will focus on improving both the magnetometers themselves and the data analysis. In particular, continuous operation should be even more stable. This is important to reliably search for signals that last longer than an hour. In addition, the previous alkali atoms in the magnetometers are to be replaced by noble gases. Under the title “Advanced GNOME”, the researchers expect this to result in considerably better sensitivity for future measurements in the search for ALPs and Dark Matter.

______________________________________________________
Dark Matter Background
Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM, denied the Nobel, some 30 years later, did most of the work on Dark Matter.

Fritz Zwicky.
Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed 30 years later by Vera Rubin.
In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.
Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970.

Vera Rubin measuring spectra, worked on Dark Matter(Emilio Segre Visual Archives AIP SPL).
Dark Matter Research

LBNL LZ Dark Matter Experiment (US) xenon detector at Sanford Underground Research Facility(US) Credit: Matt Kapust.

Lamda Cold Dark Matter Accerated Expansion of The universe http scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes. Credit: Alex Mittelmann.

DAMA at Gran Sasso uses sodium iodide housed in copper to hunt for dark matter LNGS-INFN.

Yale HAYSTAC axion dark matter experiment at Yale’s Wright Lab.

DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB (CA) deep in Sudbury’s Creighton Mine.

The LBNL LZ Dark Matter Experiment (US) Dark Matter project at SURF, Lead, SD, USA.

DAMA-LIBRA Dark Matter experiment at the Italian National Institute for Nuclear Physics’ (INFN’s) Gran Sasso National Laboratories (LNGS) located in the Abruzzo region of central Italy.

DARWIN Dark Matter experiment. A design study for a next-generation, multi-ton dark matter detector in Europe at The University of Zurich [Universität Zürich](CH).

PandaX II Dark Matter experiment at Jin-ping Underground Laboratory (CJPL) in Sichuan, China.

Inside the Axion Dark Matter eXperiment U Washington (US) Credit : Mark Stone U. of Washington. Axion Dark Matter Experiment.
______________________________________________________

See the full article here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study.

The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany.

The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, The Goethe University Frankfurt(DE) and The Technische Universität Darmstadt(DE) together form the Rhine-Main-Universities (RMU).

The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and Reichserzkanzler Adolf II von Nassau. At the time, establishing a university required papal approval and Adolf II initiated the approval process during his time in office. The university, however, was first opened in 1477 by Adolf’s successor to the bishopric, Diether von Isenburg. In 1784 the University was opened up for Protestants and Jews (curator Anselm Franz von Betzel). It fastly became one of the largest Catholic universities in Europe with ten chairs in theology alone. In the confusion after the establishment of the Mainz Republic of 1792 and its subsequent recapture by the Prussians, academic activity came to a gradual standstill. In 1798 the university became active again under French governance, and lectures in the department of medicine took place until 1823. Only the faculty of theology continued teaching during the 19th century, albeit as a theological Seminary (since 1877 “College of Philosophy and Theology”).

The current Johannes Gutenberg University Mainz was founded in 1946 by the French occupying power. In a decree on 1 March the French military government implied that the University of Mainz would continue to exist: the University shall be “enabled to resume its function”. The remains of anti-aircraft warfare barracks erected in 1938 after the remilitarization of the Rhineland during the Third Reich served as the university’s first buildings and are still in use today.

The continuation of academic activity between the old university and Johannes Gutenberg University Mainz, in spite of an interruption spanning over 100 years, is contested. During the time up to its reopening only a seminary and midwifery college survived.

In 1972, the effect of the 1968 student protests began to take a toll on the University’s structure. The departments (Fakultäten) were dismantled and the University was organized into broad fields of study (Fachbereiche). Finally in 1974 Peter Schneider was elected as the first president of what was now a “constituted group-university” institute of higher education. In 1990 Jürgen Zöllner became University President yet spent only a year in the position after he was appointed Minister for “Science and Advanced Education” for the State of Rhineland-Palatinate. As the coordinator for the SPD’s higher education policy, this furloughed professor from the Institute for Physiological Chemistry played a decisive role in the SPD’s higher education policy and in the development of Study Accounts.

From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) via phys.org : “Readout of an antiferromagnetic spintronics system by strong exchange coupling”

From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE)

via

phys.org

November 26, 2021

Fig. 1: Structure of the samples. a Cross section HAADF STEM image of the entire stack viewed along the [1¯10]-direction of Mn2Au(001). The inset shows a local Fourier transform of the Mn2Au region. b Magnified image of the Mn2Au/Py interface (region indicated by a rectangle in a), where Au atom columns have bright contrast. The inset shows a higher magnification image overlaid with a model of the crystal structure. c Crystal structure of Mn2Au with the magnetic moments pointing along the easy [1¯10]-direction. d STM image of a pristine Mn2Au(001) thin film surface with steps corresponding to half unit cells (0.42 nm) indicated by the yellow lines, one unit cell (0.85 nm) indicated by the blue lines, and three unit cells (2.55 nm) indicated by the gray line. Credit: DOI: 10.1038/s41467-021-26892-7

Within spin-based electronics (spintronics), a novel approach promising ultrafast and stable magnetic memory is based on antiferromagnets as active elements. These materials without macroscopic magnetization but with a staggered orientation of their microscopic magnetic moments display intrinsic dynamics in the Terahertz (THz) range and are robust against magnetic fields.

However, technologically relevant read-out in spintronics requires significant magnetoresistance effects, i.e., resistance changes larger than 20 percent should be associated with a reorientation of the staggered magnetization. This represents a major challenge in antiferromagnetic spintronics.

New approach enables the well-established read-out methods of ferromagnets

As published in the online science journal Nature Communications, scientists of the Institute of Physics of Johannes Gutenberg University Mainz (JGU), within an international collaboration, are now able to demonstrate a strong exchange coupling of very thin ferromagnetic layers to the prototypical antiferromagnetic spintronics compound of manganese and gold (Mn2Au). This allows us to benefit from the well-established read-out methods of ferromagnets, while the essential advantages of antiferromagnetic spintronics are only slightly diminished.

See the full article here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study.

The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany.

The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, The Goethe University Frankfurt(DE) and The Technische Universität Darmstadt(DE) together form the Rhine-Main-Universities (RMU).

The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and Reichserzkanzler Adolf II von Nassau. At the time, establishing a university required papal approval and Adolf II initiated the approval process during his time in office. The university, however, was first opened in 1477 by Adolf’s successor to the bishopric, Diether von Isenburg. In 1784 the University was opened up for Protestants and Jews (curator Anselm Franz von Betzel). It fastly became one of the largest Catholic universities in Europe with ten chairs in theology alone. In the confusion after the establishment of the Mainz Republic of 1792 and its subsequent recapture by the Prussians, academic activity came to a gradual standstill. In 1798 the university became active again under French governance, and lectures in the department of medicine took place until 1823. Only the faculty of theology continued teaching during the 19th century, albeit as a theological Seminary (since 1877 “College of Philosophy and Theology”).

The current Johannes Gutenberg University Mainz was founded in 1946 by the French occupying power. In a decree on 1 March the French military government implied that the University of Mainz would continue to exist: the University shall be “enabled to resume its function”. The remains of anti-aircraft warfare barracks erected in 1938 after the remilitarization of the Rhineland during the Third Reich served as the university’s first buildings and are still in use today.

The continuation of academic activity between the old university and Johannes Gutenberg University Mainz, in spite of an interruption spanning over 100 years, is contested. During the time up to its reopening only a seminary and midwifery college survived.

In 1972, the effect of the 1968 student protests began to take a toll on the University’s structure. The departments (Fakultäten) were dismantled and the University was organized into broad fields of study (Fachbereiche). Finally in 1974 Peter Schneider was elected as the first president of what was now a “constituted group-university” institute of higher education. In 1990 Jürgen Zöllner became University President yet spent only a year in the position after he was appointed Minister for “Science and Advanced Education” for the State of Rhineland-Palatinate. As the coordinator for the SPD’s higher education policy, this furloughed professor from the Institute for Physiological Chemistry played a decisive role in the SPD’s higher education policy and in the development of Study Accounts.

From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) via phys.org : “New insights into the structure of the neutron”

From The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE)

via

phys.org

Credit: CC0 Public Domain.

All known atomic nuclei and therefore almost all visible matter consists of protons and neutrons, yet many of the properties of these omnipresent natural building blocks remain unknown. As an uncharged particle, the neutron in particular resists many types of measurement and 90 years after its discovery there are still many unanswered questions regarding its size and lifetime, among other things. The neutron consists of three quarks which whirl around inside it, held together by gluons. Physicists use electromagnetic form factors to describe this dynamic inner structure of the neutron. These form factors represent an average distribution of electric charge and magnetization within the neutron and can be determined by means of experimentation.

Blank space on the form factor map filled with precise data

“A single form factor, measured at a certain energy level, does not say much at first,” explained Professor Frank Maas, a researcher at the PRISMA+ Cluster of Excellence in Mainz, GSI Helmholtz-Institut Mainz (DE), and GSI Helmholtzzentrum für Schwerionenforschung (DE). “Measurements of the form factors at various energies are needed in order to draw conclusions on the structure of the neutron.” In certain energy ranges, which are accessible using standard electron-proton scattering experiments, form factors can be determined fairly accurately. However, so far this has not been the case with other ranges for which so-called annihilation techniques are needed that involve matter and antimatter mutually destroying each other.

In the BESIII Experiment being undertaken in China, it has recently proved possible to precisely determine the corresponding data in the energy range of 2 to 3.8 gigaelectronvolts.

BESIII The Institute of High Energy Physics (IHEP), a Chinese Academy of Sciences research institute.

As pointed out in an article published by the partnership in the current issue of Nature Physics, this is over 60 times more accurate compared to previous measurements. “With this new data, we have, so to speak, filled a blank space on the neutron form factor ‘map’, which until now was unknown territory,” Professor Frank Maas pointed out. “This data is now as precise as that obtained in corresponding scattering experiments. As a result, our knowledge of the form factors of the neutron will change dramatically and as such we will get a far more comprehensive picture of this important building block of nature.”

Truly pioneering work in a difficult field of research

To make inroads into completing the required fields of the form factor ‘map’, the physicists needed antiparticles. The international partnership therefore used the Beijing Electron-Positron Collider II for its measurements. Here, electrons and their positive antiparticles, i.e., positrons, are allowed to collide in an accelerator and destroy each other, creating other new particle pairs—a process known as ‘annihilation’ in physics. Using the BESIII detector, the researchers observed and analyzed the outcome, in which the electrons and positrons form neutrons and anti-neutrons. “Annihilation experiments like these are nowhere near as well-established as the standard scattering experiments,” added Maas. “Substantial development work was needed to carry out the current experiment—the intensity of the accelerator had to be improved and the detection method for the elusive neutron had to be practically reinvented in the analysis of the experimental data. This was by no means straightforward. Our partnership has done truly pioneering work here.”

Other interesting phenomena

As if this was not enough, the measurements showed the physicists that the results for the form factor do not produce a consistent slope relative to the energy level, but rather an oscillating pattern in which fluctuations become smaller as the energy level increases. They observed similar surprising behavior in the case of the proton—here, however, the fluctuations were mirrored, i.e., phase-shifted. “This new finding indicates first and foremost that nucleons do not have a simple structure,” Professor Frank Maas explained. “Now our colleagues on the theoretical side have been asked to develop models to account for this extraordinary behavior.”

Finally, on the basis of their measurements, the BESIII partnership has modified how the relative ratio of the neutron to proton form factors needs to be viewed. Many years ago, the result produced in the FENICE experiment was a ratio greater than one, which means that the neutron must have a consistently larger form factor than the proton. “But as the proton is charged, you would expect it to be completely the other way round,” Maas asserted. “And that’s just what we see when we compare our neutron data with the proton data we’ve recently acquired through BESIII. So here we’ve rectified how we need to perceive the very smallest particles.”

From the micro- to the macrocosm

According to Maas, the new findings are especially important because they are so fundamental. “They provide new perspectives on the basic properties of the neutron. What’s more, by looking at the smallest building blocks of matter we can also understand phenomena that occur in the largest dimensions—such as the fusion of two neutron stars. This physics of extremes is already very fascinating.”

See the full article here.

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study.

The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany.

The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, the Goethe University Frankfurt and the Technische Universität Darmstadt together form the Rhine-Main-Universities (RMU).

The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and Reichserzkanzler Adolf II von Nassau. At the time, establishing a university required papal approval and Adolf II initiated the approval process during his time in office. The university, however, was first opened in 1477 by Adolf’s successor to the bishopric, Diether von Isenburg. In 1784 the University was opened up for Protestants and Jews (curator Anselm Franz von Betzel). It fastly became one of the largest Catholic universities in Europe with ten chairs in theology alone. In the confusion after the establishment of the Mainz Republic of 1792 and its subsequent recapture by the Prussians, academic activity came to a gradual standstill. In 1798 the university became active again under French governance, and lectures in the department of medicine took place until 1823. Only the faculty of theology continued teaching during the 19th century, albeit as a theological Seminary (since 1877 “College of Philosophy and Theology”).
Statue of Johannes Gutenberg at the University of Mainz.

The current Johannes Gutenberg University Mainz was founded in 1946 by the French occupying power. In a decree on 1 March the French military government implied that the University of Mainz would continue to exist: the University shall be “enabled to resume its function”. The remains of anti-aircraft warfare barracks erected in 1938 after the remilitarization of the Rhineland during the Third Reich served as the university’s first buildings and are still in use today.

The continuation of academic activity between the old university and Johannes Gutenberg University Mainz, in spite of an interruption spanning over 100 years, is contested. During the time up to its reopening only a seminary and midwifery college survived.

In 1972, the effect of the 1968 student protests began to take a toll on the University’s structure. The departments (Fakultäten) were dismantled and the University was organized into broad fields of study (Fachbereiche). Finally in 1974 Peter Schneider was elected as the first president of what was now a “constituted group-university” institute of higher education. In 1990 Jürgen Zöllner became University President yet spent only a year in the position after he was appointed Minister for “Science and Advanced Education” for the State of Rhineland-Palatinate. As the coordinator for the SPD’s higher education policy, this furloughed professor from the Institute for Physiological Chemistry played a decisive role in the SPD’s higher education policy and in the development of Study Accounts.