General

After three years: first particle collisions at unprecedented energies at LHC start 5th July 

The ATLAS detector more powerful than ever – with major contributions from Mainz University

University of Mainz, press release

Tomorrow (on July 5th), protons are expected once again colliding with each other at speeds close to that of light in the Large Hadron Collider (LHC) at CERN, also giving physicists of the PRISMA+ Cluster of Excellence of Johannes Gutenberg University Mainz (JGU) something to celebrate. Over the last three years, they have made important contributions to the upgrade of the ATLAS detector, ensuring that it can cope with even greater volumes of data during Run 3 of the largest particle accelerator in the world. As a result the researchers hope to gain new and more extensive insights into the universe of the very smallest particles.

On 22 April, following the more than 36-month maintenance and revamping phase, protons were once more allowed to circulate in the 27-kilometer ring of the LHC – although initially at low energy. The power of the accelerator has been continuously ramped up over the past few weeks, resulting in tomorrow’s official launch of its physics program. Protons will then be collided at a total energy of 13.6 trillion electron volts (13.6 TeV) – in other words, 6.8 TeV per electron beam.
For Run 3, the LHC team has significantly improved the capability of the accelerator and taken it to the limits of its capacity. The LHC will not only be generating particle collisions at previously unseen levels of energy but there will also be unparalleled numbers of these collisions. The four detectors of the LHC also had to undergo extensive remodeling to ensure they can keep pace with this and be able to process and analyze the correspondingly massively increased flow of data. Among these is the ATLAS detector and physicists based in Mainz played a prominent part in its modification.

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ATLAS Collaboration: Searching for new physics using asymmetric top-quark events

The ATLAS Collaboration is studying the subtle differences in the energies and directions of top and antitop quarks produced in the LHC.

Read more about this in the original PRISMA+ news item here

A new analysis, led by MPA Fellow Alexander Basan shows agreement with the Standard Model, allowing to set limits on the influence of potential new particles and interactions. The ATLAS collaboration has published the new results and explained them for laymen in a "Physics Briefing".
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IceCube analysis puts most general constraints on nonstandard neutrino interactions

Team of scientists of the PRISMA+ Cluster of Excellence lead on new publication

Link to the original PRISMA+ news release here

For decades, physicists have theorized that the current best theory describing particle physics—the "Standard Model"—was not sufficient to explain the way the universe works. In the search for physics beyond the Standard Model (BSM), elusive particles called neutrinos might point the way.

Neutrinos are sometimes called "ghost particles" because they so rarely interact with matter that they can travel through just about anything. However, while traveling through matter, they may be "slowed down", depending on the neutrino's type (or "flavor"), in what is known as a "matter effect".

In many BSM models, neutrinos have extra interactions with matter due to new and thus far unknown forces of nature. Different neutrino flavors might be affected to varying extents by these interactions, and the strength of the resulting matter effects depends on the density of matter the neutrinos are passing through. If researchers observe matter effects that can be explained as "nonstandard interactions" (NSI), it might point to new physics.

The IceCube Neutrino Observatory, an array of sensors embedded in the South Pole ice, was built to detect and study neutrinos from outer space. But in IceCube's center is a subset of more densely packed sensors called DeepCore; this region is sensitive to lower energy neutrinos formed in Earth's atmosphere that are potentially more strongly affected by nonstandard matter effects. In a paper published today in Physical Review D, the IceCube Collaboration discusses an analysis in which they examined three years of DeepCore data to see whether atmospheric neutrinos have extra interactions with matter. This analysis puts limits on all the parameters used to describe NSI, an improvement upon earlier analyses that were restricted to only the NSI regimes to which IceCube is most sensitive.

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Topping-out ceremony for laboratory and office buildings at the future Center for Fundamental Physics (CFP)

Topping-out ceremony for laboratory and office buildings at the future Center for Fundamental Physics of Johannes Gutenberg University Mainz
Above-ground counterpart to the renovation and expansion of the underground experiment halls for the MESA electron accelerator

See more at the press release here

The new Center for Fundamental Physics (CFP) at Johannes Gutenberg University Mainz (JGU) continues to grow vigorously, both underground and above ground. The topping-out ceremony for the four-story laboratory and office building CFP II has now been celebrated. With several research laboratories, a two-storey assembly hall as well as seminar and conference rooms with a total of around 3,540 square meters, the CFP II forms the aboveground counterpart to the renovation and expansion of the underground experiment halls (CFP I), in which the new MESA electron accelerator will be operated in the future.

The state and federal government are investing around 75 million euros in a high-performance structural environment for cutting-edge research by the federally funded PRISMA + Cluster of Excellence in the field of particle and hadron physics, which deals, for example, with research into dark matter, the properties of which have so far only been inferred indirectly can be. The construction project is being managed by the Mainz branch of the State Office for Real Estate and Construction Management. The handover of the building to JGU is planned for summer 2023.

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Prof Alfons Weber

I hold a joint professorship at the University of Mainz and Fermilab and are a visiting professor at the University of Oxford. My main research interest is in neutrino physics, but I am also active in developing electronics and novel detectors.

Fun facts:

Research

I started my career in physics doing a diploma thesis in phenomenology, looking into novel way of detecting relict neutrinos from the big bang, or solar and accelerator neutrinos. After this more theoretical start at the RWTH-Aachen, I switched to experimental physics and did my Ph.D. and first post-doc at the L3 experiment at the LEP collider at CERN. I searched for new particles (but didn't find any) and made precision measurements of the W-boson mass.

I returned to neutrino, when I came to Oxford in 1999. I started to lead the Oxford MINOSgroup, who looks into the phenomenon of neutrino oscillations at Fermilab. We made a precision measurements using muon neutrinos from the NuMI beam line. More information can be found at the Fermilab MINOS page.

Later I joint the T2K experiment in Japan, which looks for electron neutrino appearance in a muon neutrino beam. We were awarded the Breakthrough Prize in Fundamental Physics for the measurement of neutrino oscillations and even found the first indication that neutrinos and anti-neutrinos don't oscillate in the same way. This process may eventually hold the key to understand why there is more matter than anti-matter in the universe. We need a new generation of experiments to really unlock the secret of the neutrino.

The DUNE Experiment is exact this. This very long baseline neutrino oscillation experiment is located in a neutrino beam that goes from Fermilab for 1300 km to the Sanford Underground Research Facility (SURF). The DUNE far detector will consist of 70,000 tons of liquid argon and will have an unprecedented sensitivity to measure neutrino oscillation. Its main aim is not only to study the matter anti-matter asymmetry, but to look for neutrino from supernova explosions or for the decay of the proton. I was the UK PI of the project and also leading a team to design the near detector, which is an essential component of the experiment to study the neutrino beam composition and the details of the neutrino interactions. I am the chair of the Institute Board of the International DUNE Collaboration.

I have also developed a novel detector for neutrino and neutron detection. These activities lead to the creation of the SoLid experiment, which searches for sterile neutrinos at the research reactor BR2 in Mol, Belgium.

Committees

I was serving on the STFC Science Board that provides advice to STFC Council and the executive on all aspects of STFC's science and technology programme.

I was on the Executive Committee of the MINOS and NOvA Experiments and was the chair of the institutional board and a member of the Executive Committee of the LAGUNA-LBNO design study. I am now the chair of DUNE's Institute board.

I am a member of the LHCC advising the CERN management on the LHC experiments concentrating on CMS and the WLCG.

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Common professorship appointment with Fermilab: Alfons Weber becoming member of ETAP

PRISMA+-research programme in neutrino physics further expanded

University Press release

Neutrino research is an important focus of the PRISMA + Cluster of Excellence at Johannes Gutenberg University Mainz (JGU): Mainz researchers are involved in many large-scale international experiments at the South Pole, in Italy and in China. Now, JGU and the Fermilab Prof. Dr. Alfons Weber appointed as the new W3 professor. The proven neutrino expert is moving from the renowned Oxford University to Mainz and will further strengthen the neutrino research program. His focus is on promoting German participation in the next major neutrino experiment, the Deep Underground Neutrino Experiment (DUNE) at the Fermilab near Chicago.
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Solar CNO neutrinos observed for the first time

Characteristic neutrinos are evidence of the secondary fusion process that powers our sun

University Press release

Scientists from the Borexino collaboration have provided the first experimental proof of the occurrence of the so-called CNO cycle in the sun: They were able to directly observe characteristic neutrinos that arise during this fusion process. This is an important milestone towards a complete understanding of the fusion processes in the sun. Even more: While the CNO cycle plays a subordinate role in the sun, it is probably the predominant way of generating energy in stars, which are much heavier and therefore hotter than the sun. The results of the Borexino collaboration are published in the current issue of Nature.
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Surprising Signal in the XENON1T Dark Matter Experiment

Scientists of the PRISMA+ Cluster of Excellence of the Johannes Gutenberg University Mainz significantly involved

University Press release

Scientists from the international XENON collaboration announced today that data from their XENON1T, the world's most sensitive dark matter experiment, show a surprising excess of events. The scientists do not claim to have found dark matter. Instead, they say to have observed an unexpected rate of events, the source of which is not yet fully understood. The signature of the excess is similar to what might result from a tiny residual amount of tritium (super heavy hydrogen), but could also be a sign of something more exciting: the existence of a new particle known as the solar axion or the indication of previously unknown properties of neutrinos.
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From China to the South Pole: Joining forces to solve the neutrino mass puzzle

Study by Mainz physicists indicates that the next generation of neutrino experiments may well find the answer to one of the most pressing issues in neutrino physics

University Press release

Among the most exciting challenges in modern physics is the identification of the neutrino mass ordering. Physicists from the PRISMA+ Cluster of Excellence at Johannes Gutenberg University Mainz (JGU) play a leading role in a new study that indicates that the puzzle of neutrino mass ordering may finally be solved in the next few years – thanks to the combined performance of two new neutrino experiments that are in the pipeline, the upgrade of the IceCube experiment at the South Pole and the Jiangmen Underground Neutrino Observatory (JUNO) in China. They will soon give the physicists access to much more sensitive and complementary data on the neutrino mass ordering.
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