1 / 26

Ivan Logashenko for Mu2e Collaboration

Workshop on e+e - collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia. Ivan Logashenko for Mu2e Collaboration. Search for cLFV. We had several talks on cLFV already – MEG, COMET, BELLE,… Why is it interesting?

scot
Download Presentation

Ivan Logashenko for Mu2e Collaboration

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Workshop on e+e- collisions from Phi to Psi, Sep.19-22, 2011 Novosibirsk, Russia Ivan Logashenko for Mu2e Collaboration

  2. Search for cLFV • We had several talks on cLFV already – MEG, COMET, BELLE,… • Why is it interesting? • Charged Lepton Flavour Violation in SM is extremely small. Any detectable signal is a sign of New Physics. • Why muons? • Copiusly produced • We are trying to measure • Standard Model predicts extremely small value: e+e- collisions from Phi to Psi

  3. History of Mu2e • The current best limit was obtained at SINDRUM II experiment (90’s-2000) • Mu2e is the successor of two earlier proposals: • MELC at Moscow, early 90’s • The main ideas of the experimental design were proposed • MECO at Brookhaven, early 2000’s • Part of RSVP program, along with KOPIO, search for K->pinunu • At lof of design work and R&D were performed before the program was terminated • Mu2e goal: e+e- collisions from Phi to Psi

  4. Mu2e vs MEG μ → eγ decay and μN → eN conversion are complementary “Model-independent” lagrangian: Mu2e @ProjectX Mu2e k << 1 magnetic moment type m → egrate ~300X mN → eN rate MEG MEG 2011 k >> 1 four-fermion interation almost no contribution to m → eg MEGA SINDRUM II e+e- collisions from Phi to Psi

  5. Overview of the technique Stop muons in aluminum Muons quickly get to 1S orbit Lifetime of muonic atom is 864 ns Look for 105 MeV electron Hydrogen-like atom Bohr radius ≈20 fm Nucleus radius ≈4 fm Use X-rays to monitor number of muons Most of the background is well below this energy e+e- collisions from Phi to Psi

  6. Background: Muon decay-in-orbit (DIO) For decay-in-orbit , the maximum energy of electron is equal to the energy of conversion electron (≈105 MeV). The high-energy tail Need good energy resolution to beat this background! Free muon In-orbit Long tail! e+e- collisions from Phi to Psi

  7. Background: Radiative muon capture (RMC) Muon capture is the source of many background particles: • This background is mostly low energy, but: • RadiativeMuon Capture: • with small BR≈10-5, γ’s from muon captures can have high energy up to • source of high energy electrons, comparable with DIO at the tail: γ can convert in target to e+e- pair, and electron can get almost all energy • With good energy resolution and proper choice of target (MZ-1>MZ) this source of background is under control e+e- collisions from Phi to Psi

  8. Background: Radiative pion capture (RPC) • Muon are produced from pion decays, therefore there are pions in the muon beam. • RadiativePion Capture: • pions stop at the target and promptly annihilate on the nucleus • with BR~10-2, γ is produced with energy up to 137 MeV (for Al) • source of high energy electrons: γ can convert in target to e+e- pair, and electron can enough energy to mimic conversion electron • This is prompt background, it quickly dies away. Solution: pulsed beam. Time distribution of stopped pions in the target e+e- collisions from Phi to Psi

  9. Overview of the design Production Solenoid 4 m long Transport Solenoid 13 m long Detector Solenoid 12 m long e+e- collisions from Phi to Psi

  10. Historical perspective: MELC proposal (1992) e+e- collisions from Phi to Psi

  11. Production Solenoid e+e- collisions from Phi to Psi

  12. Extinction To avoid prompt background, we use pulsed beam The signal is extremely rare Need extinction factor 10-10! …and it has to be measured Use combination of techniques to achieve this factor e+e- collisions from Phi to Psi

  13. Accelerator e+e- collisions from Phi to Psi

  14. Mu2e vs NOvA vs g-2 • Mu2e can operate concurrently with FNAL neutrino experiments (NOvA) • we use 6 out of 18 Booster batches, which NOvA can’t use during Main Injector cycle • G-2 and Mu2e use the same beam, but in a different manner • cannot run concurrently, but there is effort to make it possible to switch between the experiments e+e- collisions from Phi to Psi

  15. Muon Beam Line • Negative gradient • magnetic mirrow • no trapped particles • Uniform field in tracker region • good resolution • Torroidal field in the transport solenoid • separation e+e- collisions from Phi to Psi

  16. Transport Solenoid e+e- collisions from Phi to Psi

  17. Stopping target • 17 Al disks, 200 mkm thickness • Why Aluminum? Perfect for this experiment • higher Z: • larger conversion rate • different contributions to the rate • lower Z: • larger lifetime • higher conversion energy e+e- collisions from Phi to Psi

  18. T-tracker 18 stations x 12 panels x 2x50 straws =21600 straws 5 mm dia. Mylar straws, 15 μm walls, 20 μm Au-plated W wire 200 μm position resolution e+e- collisions from Phi to Psi

  19. Measuring the momentum Low energy e- pass undetected For high energy e- we detect several points on the helix e+e- collisions from Phi to Psi

  20. Calorimeter • Located downstream of tracker • Main purpose: to provide trigger (1 kHz for E>80 MeV) • Provides redundant position, timing and energy data • Possible design: • 2112 LYSO crystals, • 3x3x13 cm3arranged in 4 vanes. Density 7.3g/cm3, Moliere radius 2.07 cm, Rad. Length 1.14 cm, decay time 40 ns. Light yield relative to NaI 85%. • Two APDs per crystal e+e- collisions from Phi to Psi

  21. Cosmic Ray Shield Cosmic rays can generate high energy electrons Need high suppression factor – a lot of cosmic ray events over 2 year running period Combination of passive (magnetized iron + dirt) and active (scintillation counters) shielding 99.99% coverage e+e- collisions from Phi to Psi

  22. Expected sensitivity e+e- collisions from Phi to Psi

  23. What we expect to see e+e- collisions from Phi to Psi

  24. Project schedule e+e- collisions from Phi to Psi

  25. Project X There is proposal to replace FNAL’s Booster with new 8 GeV high-intensity linear accelerator, based on ILC technologies – “Project X” Project X would feed neutrino and rare decay/high precision experiments Potential to upgrade Mu2e by factor x100! • set much stronger limits (if there is no signal) • or use different target materials to study nature of new physics (if there is signal) • Serious upgrade of the detector is required e+e- collisions from Phi to Psi

  26. Conclusion • In May 2008 P5 (US Particle Physics Project Prioritization Panel) Report stated: • “recommends pursuing the muon-to-electron conversion experiment under all budget scenarios considered by the panel.” • Why? • Mu2e experiment will allow to improve the current limit by 4 orders of magnitude • if signal is found, it will be an undeniable proof of the New Physics and it will provide data, complementary to LHC • if no signal is found, it will set constrains much stronger than LHC (up to 1000 TeV mass scale) • with better muon source and other upgrades, the limits can be improved by another 2 orders of magnitude e+e- collisions from Phi to Psi

More Related