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Fundamentale Myonenphysik am Paul Scherrer Institut

English title Fundamental Muon Physics at the Paul Scherrer Institute
Applicant Ritt Stefan
Number 137738
Funding scheme Project funding (Div. I-III)
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Particle Physics
Start/End 01.02.2013 - 31.08.2015
Approved amount 130'598.00
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Keywords (2)

Myonzerfall; Standardmodell der Teilchenphysik

Lay Summary (German)

Lead
Lay summary
Theoretisch Physiker entwickeln zahlreiche Modelle, um die Welt der Elementarteilchen zu beschreiben. Welche Modelle hiervon richtig sind, müssen Experimente zeigen. Ein Weg, mithilfe von Experimenten die Voraussagen der Modelle zu testen, ist die Beobachtung von Teilchenzerfällen.

Die meisten Elementarteilchen sind instabil und zerfallen nach kurzer Zeit in andere Teilchen. Dabei gibt es meist mehrere Möglichkeiten, was die Zerfallsprodukte sein können. Der Anteil einer bestimmten Zerfallsart an allen Zerfällen ist dabei eine wertvolle Messgrösse. Sollte ein bestimmter Zerfall deutlich öfter (oder weniger oft) beobachtet werden als vom Standardmodell vorausgesagt, wäre das ein deutlicher Hinweis auf sogenannte neue Physik, die eine Beschreibung in einem neuartigen Modell nötig macht.

Das MEG Experiment am Paul Scherrer Institut PSI untersucht den Zerfall des positiv geladenen Myons. Das Myon ist gewissermassen der schwere Bruder des Elektrons und zerfällt innerhalb von rund 2 Millionstelsekunden in ein Positron, also ein positv geladenes Elekrton, und zwei Neutrinos. Zerfiele es hingegen in ein Positron und ein Photon (Lichtteilchen), so wäre das ein bisher unbeobachteter Zerfall und ein eindeutiger Beweis für neue Physik jenseits des etablierten Standardmodells. Das MEG Experiment wurde in den vergangenen zehn Jahren von einer internationalen Forschergruppe geplant, gebaut und betrieben. Es benutzt den momentan weltweit intensivsten Myonestrahl am PSI von 30 Millionen Myonen pro Sekunde. Damit gelang es 2011, die bisherige Genauigkeit für den Zerfall von einem Myon in 100 Milliarden um den Faktor fünf zu verbessern.

Das aktuelle Forschungsgesuch bezieht sich eine Erweiterung des Experiments, um die Genauigket nochmals um einen Faktor zu verbessern. In Zusammenarbeit mit den beteiligten Partnern werden Teile des Detektors neu entworfen, gebaut und getestet. Die für den Detektor notwendige Elektronik wird weiter verbessert und wie bisher im Rahmen des Technologietransfers des PSI der Wissenschaft und Indsustrie zur Verfügug gestellt. Zudem soll die Ausbildung von Doktoranden auf dem Gebiet der experimentellen Teilchenphysik intensiviert werden.

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Collaboration

Group / person Country
Types of collaboration
Universität Heidelberg Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Joint Annual Meeting of the Austrian & Swiss Physical Societies Talk given at a conference The Compact Muon Beam Line for the Mu3e Experiment 01.09.2015 Wien, Austria Berg Felix Anton; Kettle Peter-Raymond;
ETH/Uni. ZH Ph.D. Seminar Talk given at a conference The Compact Muon Beam Line for the Mu3e Experiment 27.08.2015 Zürich, Switzerland Berg Felix Anton; Kettle Peter-Raymond;
International Workshop on Future Compact Muon Sources Poster Compact Muon Beam Line at PSI 21.01.2015 Huddersfield, Great Britain and Northern Ireland Berg Felix Anton; Kettle Peter-Raymond;
Annual Meeting of the Swiss Physical Society SPS Meeting Talk given at a conference Mu3e Experiment Compact Beam Line 02.07.2014 Fribourg, Switzerland Kettle Peter-Raymond; Berg Felix Anton;
13th International Conference on Muon Spin Rotation, Relaxation and Resonance Poster Feasibility study for a new high-intensity muon beam line (HiMB) at PSI 01.06.2014 Grindelwald, Switzerland Berg Felix Anton; Kettle Peter-Raymond;
3rd International Workshop on the Physics of Fundamental Symmetries and Interactions at low energies and the precision frontier Poster HiMB – A possible Next Generation High-intensity Muon Beam Facility for Particle Physics & Materials Science 09.09.2013 Villigen PSI, Switzerland Ritt Stefan; Hildebrandt Malte; Kettle Peter-Raymond; Berg Felix Anton;
ETH/Uni. ZH Ph.D. Seminar Talk given at a conference The Initial Study of a Compact Beam Line for the Mu3e Experiment 29.08.2013 Zürich, Switzerland Berg Felix Anton; Kettle Peter-Raymond;


Associated projects

Number Title Start Funding scheme
157742 Data Acquisition System for the MEG II Experiment 01.07.2015 R'EQUIP
162654 Fundamentale Myonenphysik am Paul Scherrer Institut 01.11.2015 Project funding (Div. I-III)
162654 Fundamentale Myonenphysik am Paul Scherrer Institut 01.11.2015 Project funding (Div. I-III)

Abstract

Tests of fundamental theories in particle physics and searches for “New Physics” beyond the Stan-dard Model (SM) can be performed at the high-energy frontier, where new particles can be created directly using TeV-scale accelerators such as the LHC. An alternative approach is the high-precision frontier, where particle decays and interactions measured with extreme precision can reveal indications of new physics through virtual loops involving possible new particles. An attractive probe for such measurements is the muon. Both the decay of the muon and its interaction with other particles can be used as a stringent test of the SM. The fact that the muon is about 200 times heavier than the electron makes these processes more sensitive to many parameters or extensions of the SM. As the SM describes different processes in a unified manner, muonic reactions can also provide important information about fundamental astrophysics reactions involving electrons, which are too weak to be measured directly in the laboratory. This SNF request is a joint application covering several activities of PSI’s fundamental muon programme.The MEG experiment searches for the decay mu->e gamma, which would violate lepton flavour and is therefore forbidden in the SM, but predicted to exist in most theories beyond the SM. The experiment aims to improve the current experimental limit of the branching ratio by about two orders of magnitude. The ex-periment took first physics data in 2008, and will continue for the next two to three years, pushing the branching ratio limit to a few times 10^-13. Following that, the experiment will reach its limits originating from systematics and background, and a detector upgrade is then necessary to push the limit beyond the current goal. This upgrade requires detailed Monte Carlo studies and a good understanding of the current operation of the experiment. We therefore ask for two PhD positions (A, B) and for 40 kCHF for equipment, materials and travel. The students will participate in the current data-taking and analysis to become acquainted with the experiment, and then start upgrade studies for the Drift Chamber system and the muon beam line, the latter being also of great interest for future projects such as the search for the mu->e+e+e- decay.The goal of the MuSun experiment is a measurement of the rate of the semileptonic weak process mu d -> n+n+nu to a precision of better than 1.5%. Muon capture on the deuteron is the simplest weak interac-tion process on a nucleus that can both be calculated and measured to a high degree of precision. This process is closely related to one of the most important nuclear reactions of the universe, solar pp-fusion, and the mu d-reaction, which was critical for establishing solar neutrino oscillations. We ask for the support of one postdoctorial research assistant (PDRA) and one PhD (C) student and 85 kCHF for equipment, material and travel. The PRDA and student thus will play an essential role in developing the new beam line and commis-sioning the experiment there. They will become the local experts in upgrading the complex cryo-detector and gas purification system, work that can only be performed at PSI and will be supported by experts from PSI and from within the international collaboration. They will play a leading role in the main physics and systematics runs planned for 2013 and 2014 in the new beam line.
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