MUG-TEST 1 L’esperimento MEG A. Baldini 17 settembre 2002

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1 MUG-TEST 1 L’esperimento MEG A. Baldini 17 settembre 2002 http://meg.pi.infn.it

2 MUG-TEST 2 Layout della presentazione Introduzione fisica Descrizione dei rivelatori Sensibilita’ dell’esperimento Necessita’ finanziarie

3 MUG-TEST 3 Motivazioni SUSY SU(5) predictions Lepton Flavour Violation (LFV) induced by finite slepton mixing through radiative corrections The mixing could be large due to the top-quark mass in SU(5) (larger by ~30 order of magnitudes than SM predictions) SO(10) predicts even larger BR J.Hisano et al.,Phys. Lett. B391 (1997) 341 R. Barbieri et al.,Nucl. Phys. B445(1995) 215  clear evidence for physics beyond the SM Our goal Analisi combinate degli esperimenti a LEP favoriscono

4 MUG-TEST 4 Limiti combinati degli esperimenti LEP per SUGRA MSSM

5 MUG-TEST 5 SO10

6 MUG-TEST 6 Connection with neutrino oscillations J.Hisano et al.,Phys. Lett. B437 (1998) 351 -oscillations Contribution to slepton mixing from (mixing responsible for solar -deficit)

7 MUG-TEST 7 muon (g-2) Results from BNL experiment Sizeable deviations (  tan  ) are expected   e  ) enhanced More recently: hep-ex/0208001 v2(2002) dal valore “predetto” g-2

8 MUG-TEST 8 - dal decadimento di a riposo sulla superficie del bersaglio (surface muons) - misure nel 1999: contaminazione circa 10% Il fascio

9 MUG-TEST 9 Studi di fascio -Studio della versione “U” per migliorare la separazione dai positroni - Misure estive e a fine anno

10 MUG-TEST 10 Detector overview Liquid Xe e.m. calorimeter Magnetic spectrometer Timing counter FWHM resolutions “espulsione” dei positroni

11 MUG-TEST 11 Montecarlo Simulazione di tutte le parti del rivelatore

12 MUG-TEST 12 COBRA spectrometer Gradient field Uniform field COnstant Bending RAdius (COBRA) spectrometer Constant bending radius independent of emission angles Low energy positrons quickly swept out

13 MUG-TEST 13 Il magnete 3 raggi diversi di avvolgimento Cavo superconduttore gia’ prodotto Test su prototipi per verificare che gli stress meccanici possono essere sostenuti

14 MUG-TEST 14 Campo magnetico lungo l’asse e nella zona dei fototubi del calorimetro e.m.

15 MUG-TEST 15 Camere a drift Catodi sagomati per una buona risuoluzione longitudinale Miscela He/C 2 H 6 (50%/50%)

16 MUG-TEST 16 (no magnetic field) R&D delle camere a drift

17 MUG-TEST 17 Miglioramento della lettura e prestazioni dello spettrometro

18 MUG-TEST 18 Dipendenza del limite (90% C.L.) dalla risoluzione longitudinale

19 MUG-TEST 19 Timing counter

20 MUG-TEST 20 TC prototype results (although depend on the number of photoelectrons) from rms of (T3-T4)/2 distribution almost independent of muon passage along the counter (T1 - T2)/2 independent of reference gives similar results Weighted average We obtain

21 MUG-TEST 21 Timing MC studies Timing efficiency   60 ps for  E  2 MeV mainly dominated by photoelectron statistics   E > 5 MeV energy deposit on adjacent  -cells to achieve 100 ps FWHM resolution Trigger efficiency Use of hit z-cells and  -cells to determine initial positron direction  correlation with max. charge PMT in LiXe calorimeter (providing  direction) Yet to be studied: use of Q1/Q2 (instead of z-cells layer) to determine the z-position e+ use of more than 2 PMT’s need to know T(E,x,z)

22 MUG-TEST 22 Efficiencies Timing efficiency evaluated for different configurations: 1cm thick inner layer, 2 cm thick outer layer  (  E>5 MeV) = 85 % (mainly due to e+ interaction in the inner layer)  (trigger) = 96.8 % 0.5 cm thick inner layer, same thickness for outer  (  E>5 MeV) = 93.6 %  (trigger) = 97.4 % reversed layers  (  E>5 MeV) = 97.5 %  (trigger) = 75.4 % ( many events with no hit on z-sliced layer) unavailable provided one uses Q1/Q2 to determine z

23 MUG-TEST 23 Configurazione dei rivelatori dello spettrometro

24 MUG-TEST 24 Il calorimetro a xenon liquido

25 MUG-TEST 25 Large calorimeter prototype 264 PMTs, 100 l LiXe Use of inverse-Compton scattered  -beam provided at TERAS, AIST, Tsukuba, Japan  -energy spread < 1% at Compton edge E = 40 MeV Test with alphas and cosmic rays (movable telescope) INFN participation

26 MUG-TEST 26

27 MUG-TEST 27 Risoluzione in energia

28 MUG-TEST 28 Detector resolutions Posizione Nuove misure sul Large Prototype

29 MUG-TEST 29 Trigger Use of “on-line” reconstruction of energy, direction for both positron and photon Photon PMT charge sum  energy deposit Use of 100 MHz FADC max. charge PMT  direction Positron DCs provide information about positron momentum (constant bending radius) and direction (correlation of chamber plane index with  ) but slower device (~200 ns drift)  information available only at high-level trigger Timing Counters instead: provide fast (~10 ns) information about timing and direction (correlation of scintillator slices with positron direction) work as a filter (e.g. no hit on TC) for Michel positrons with p<40 MeV/c or out of the acceptance angular range ( )

30 MUG-TEST 30 1st level trigger Coincidence of an event in Xe with a TC hit within ΔT = 10 ns Since then 2nd level trigger Based on an association of γ direction with TC-rods hit by the positron (hard to improve due to target size) 3rd level trigger Use of outer hit DC wires to determine the radius of the turning point By requiring Trigger levels

31 MUG-TEST 31 Trigger implementation Use of 100 MHz, 10-bit resolution Flash-ADC for PMT charge sampling Data processed by FPGA so as to: subtract the pedestals equalize the PMT gain compute the Q-sum find the PMT with max charge compute the min. arrival time store waveforms in FIFO Two types of VME board 1-Analog-to-Digital 6U 2-Digital 9U arranged in a layer tree structure 1 board 2 VME 6U 1 VME 9U Type2 LXe inner face (312 PMT)... 20 boards 20 x 48 Type1 16 3 Type2 2 boards... 10 boards 10 x 48 Type1 16 3 LXe lateral faces (488 PMT: 4 to 1 fan- in) Type2 1 board... 12 boards 12 x 48 Type1 16 3 Timing counters (160 PMT) Type2 2 boards 2 x 48 4 x 48 2 x 48

32 MUG-TEST 32 Readout: digitizzazione a 2 - 2.5 GHz Primo prototipo pronto a fine anno

33 MUG-TEST 33 Segnale: Sensibilita’ Il rate e’ abbassato per avere ~ 0.5 eventi di fondo e 1 evento di segnale Scoperta: 4 eventi misurati (P ) In tal caso il rate di muoni verra’ aumentato per migliorare la comprensione del fondo e capire meglio il segnale

34 MUG-TEST 34 Fondi Fondo Accidentale: un positrone di Michel ed un fotone dal decadimento radiativo o dall’annichilazione di un positrone Fondo prompt: dal decadimento radiativo (calcolabile)

35 MUG-TEST 35 Photon yield

36 MUG-TEST 36 K L 0  e K   e  A  eA  eee  e  Previous searches After Y. Kuno and Y. Okada Limits improved by ~ 2 orders of magnitude in the last 25 years Since 1948 E.P.Hincks and B.Pontecorvo, PR 73 (1948) 257 1940195019601970198019902000 BR year

37 MUG-TEST 37 INFN & Pisa University A. Baldini, C. Bemporad, F.Cei, M.Grassi, D. Nicolo’, R. Pazzi, F. Sergiampietri, G. Signorelli ICEPP, University of Tokyo T. Mashimo, S. Mihara, T. Mitsuhashi, T. Mori, H. Nishiguchi, W. Ootani, K. Ozone, T. Saeki, R. Sawada, S. Yamashita KEK, Tsukuba T. Haruyama, A. Maki, Y. Makida, A. Yamamoto, K. Yoshimura Osaka University Y. Kuno Waseda University T. Doke, J. Kikuchi, H. Okada, S. Suzuki, K. Terasawa, M. Yamashita, T. Yoshimura Budker Institute, Novosibirsk L.M. Barkov, A.A. Grebenuk, D.G. Grigoriev, B, Khazin, N.M. Ryskulov PSI, Villigen J. Egger, P. Kettle, S. Ritt The MEG collaboration INFN & Pavia University A.de Bari, P. Cattaneo, G. Cecchet INFN & Genova University F. Gatti

38 MUG-TEST 38 Stima dei costi

39 MUG-TEST 39 Preventivo globale

40 MUG-TEST 40 Pisa 2003

41 MUG-TEST 41 Finanziamenti/anticipi 2003 Pisa M.E. 2 m.u. PSI + 0.5 Giappone M.I. 5 k€ Inv + Consumo 25 k€ PMT (10) + 75 k€ LXe facility Pavia M.E. 1 m.u. PSI M.I. 2 k€ Inv. + Consumo 50 k€ test PMT in c.m. Rimborsi dotazioni (no) Genova M.E. 0.5 m.u. PSI M.I. 1 k €

42 MUG-TEST 42 LXe Facility 1) Gruppo di pompaggio con: pompa vuoto primario scroll (2 stadi, a secco, senza olio) pompa secondario turbomolecolare (a secco) 10 kEuro 2) Misuratori di vuoto 2 kEuro 3) Cercafughe (scroll+turbo+cella analisi)20 kEuro 4) Dewars, flange CF, tuberie, valvole23 kEuro 5) Criostato per Xenon liquido, con scambiatore di calore a LN2, finestre, passanti alta e bassa tensione, componentistica vuoto varia.20 kEuro Totale75 kEuro