1. Giovanni Onorato Fermilab University of Rome “Guglielmo Marconi” INFN Lecce Mu2e general presentation

2. / 156 / 28 / 2011 2 Particle physics frontiers - Neutrino experiments (NOvA, LBNE, MINOS, MINERvA, and others… ) - Precision measurements (g-2) - Rare decays (Mu2e) Mu2e collaboration

3. / 156 / 28 / 2011 3 The lepton flavor violation Neutrinos have mass, so in the SM we can have Rate < 10 -54 (unmeasurably low) In new physics models one can have or in presence of a nucleus… Experiments:Mu2e, SINDRUM II, TRIUMF, COMMET, and others… Rate ~ 10 -15

4. / 156 / 28 / 2011 4 Present measurements

5. / 156 / 28 / 2011 5 Mu2e achievements

6. / 156 / 28 / 2011 6 Experimental setup 1 Proton beam hits production target in Production Solenoid. Pions captured and accelerated towards Transport Solenoid by graded field. Pions decay to muons.

7. / 156 / 28 / 2011 7 Experimental setup II Transport solenoid performs sign and momentum selection. Eliminates high energy negative particles, positive particles and line-of- sight neutrals. Muons captured in stopping target. Conversion electron trajectory measured in tracker, validated in calorimeter. Cosmic Ray Veto surrounds Detector Solenoid.

8. / 156 / 28 / 2011 8 Dominant background

9. / 156 / 28 / 2011 9 Other background sources - Radiative muon/pion capture - Photon produced that can convert asymmetrically - Beam electrons can scatter in target - Muon/pion decay in flight - Antiprotons and other late arriving particles - Cosmic-ray induced electrons - Protons - Neutrons - Photons from Nuclear capture None of them produce a sharp peak at 105 MeV: they need to be well known and controlled. Work is going on on this

10. / 156 / 28 / 2011 10 Detectors: the T-Tracker 18 stations + Stiffening rings at ends 12 panels, at 30° rotations, form a station 30° stereo angles give 400m resolution along wire Straw termination and readout at r>70cm

11. / 156 / 28 / 2011 11 T-Tracker: straws structure 5mm straws Gaps between straws Double layer

12. / 156 / 28 / 2011 12 Alt. ITracker (from INFN Lecce)

13. / 156 / 28 / 2011 13 The calorimeter (from INFN Frascati/Pisa)

14. / 156 / 28 / 2011 14 Location

15. / 156 / 28 / 2011 15 Time schedule