MEG  e  search at PSI: SUGRA indications SUSY SU(5) predictions BR (  e  )   SUSY SO(10) predictions BR SO(10)  100 BR SU(5) R. Barbieri et al., Phys. Lett. B338(1994) 212 R. Barbieri et al., Nucl. Phys. B445(1995) 215 LFV induced by slepton mixing Our goal Experimental limit combined LEP results favour tan  >10 in the Standard Model !!

MEG: Experimental method Easy signal selection with  + at rest e +  +  Ee = E  = 52.8 MeV  e  = 180° Detector outline Stopped beam of  /sec in a 150  m target Photon detector Liquid Xenon calorimeter for  detection (scintillation) - fast: 4 / 22 / 45 ns - high LY: ~ 0.8 * NaI - short X 0 : 2.77 cm 1 MeV Cockroft-Walton for continuous calorimeter calibration Positron spectrometer Solenoid spectrometer & drift chambers for e + momentum Scintillation counters for e + timing CW beam line

Univ. of Tokyo Y. Hisamatsu, T. Iwamoto, T. Mashimo, S. Mihara, T. Mori, Y. Morita, H. Natori, H. Nishiguchi, Y. Nishimura, W. Ootani, K. Ozone, R. Sawada, Y. Uchiyama, S. Yamashita KEK T. Haruyama, K. Kasami, A. Maki, Y. Makida, A. Yamamoto, K. Yoshimura Waseda Univ. K. Deguchi, T. Doke, J. Kikuchi, S. Suzuki, K. Terasawa INFN Pisa A. Baldini, C. Bemporad, F. Cei, C. Cerri, L. Galli, G. Gallucci, M. Grassi, D. Nicolò, F. Sergiampietri, G. Signorelli INFN and Univ. of Genova M. De Gerone, S. Dussoni, F. Gatti, S. Minutoli, P. Musico, P. Ottonello, R. Valle INFN and Univ. of Pavia G. Boca, P. W. Cattaneo, A. De Bari, R. Nardo’, M. Rossella INFN and Univ. of Roma I C. Cavoto, G. Piredda, F. Renga C. Voena, D. Zanello INFN and Univ. of Lecce M. Panareo Paul Scherrer Institute A.Papa, M. Hildebrandt, P.-R. Kettle, S. Ritt, O. Kiselev BINP Novosibirsk L. M. Barkov, A. A. Grebenuk, D. N. Grigoriev, B. I. Khazin, N. M. Ryskulov JINR Dubna A. Korenchenko, N. Kravchuk, A. Moiseenko, D. Mzavia Univ. of California, Irvine W. Molzon, M. Hebert, P. Huwe, J. Perry, V. Tumakov, F. Xiao, S. Yamada MEG  ~40 FTEs The MEG collaboration

TCs DCs Calo. NaI C-W: “Essential Tool” “Essential Tool” Li (17.6, 14.6 MeV) + B (4.4, 11.7, 16.1 MeV) lines – Energy + Timing C-W: “Essential Tool” “Essential Tool” Li (17.6, 14.6 MeV) + B (4.4, 11.7, 16.1 MeV) lines – Energy + Timing NaI:  charge exch,reaction  charge exch,reaction on p   0  55/83 MeV  on p   0  55/83 MeV  back to back trigger back to back trigger automated mover automated mover  E/E ~5-6% (  )  E/E ~5-6% (  )NaI:  charge exch,reaction  charge exch,reaction on p   0  55/83 MeV  on p   0  55/83 MeV  back to back trigger back to back trigger automated mover automated mover  E/E ~5-6% (  )  E/E ~5-6% (  ) C-W

2008 data analysis: blind analysis: E  vs  t  e window

J.Adam et al., Nucl. Phys. B 834(2010), 1

90% CL limit 90 % C.L. N Sig  14.6 corresponds to BR(  →e  )  2.8 x Computed sensitivityComputed sensitivity 1.3 x Statistical fluctuation ~5%Statistical fluctuation ~5% From side bands analysis we expected 0.9 (left) and 2.1 (right) x From side bands analysis we expected 0.9 (left) and 2.1 (right) x Bad luckBad luck

8 2 months of data taking in 2009:

9 Problem on DCHs  problem in HV distribution cards All chambers repaired before start of 2009 beam time Hit map

run Smoother: LXe clean, DCHs working properly Shorter run: another experiment (muonic atom Lamb shift) having good results Transverse (fibers+APD) timing counter still missing: noise induced in DCHs DCHs resolutions though improved are not yet at the proposal level (electronic noise ). Synchronization between different electronic channels measuring timing not yet at good level (solved: DRS4 firmware problem)

Calibrazione con fascio di positroni Use of tuned monochromatic positron beam being investigated as a means of e.g. studying our positron spectrometer tracking efficiency vs. emission angle or momentum, with high statistics, in a momentum range equivalent to real MEG- conditions!!! Mechanism:positron-Nucleus elastic scattering from light nuclei at around Mechanism: positron-Nucleus elastic scattering from light nuclei at around P e ~ 50 MeV/c “Coherent” P e ~ 50 MeV/c “Coherent” nuclear recoil, spin-effects, magnetic terms all ~ negligable nuclear form-factor introduces a small effect X-sections “well known”  basically “Mott-scattering” Mechanism:positron-Nucleus elastic scattering from light nuclei at around Mechanism: positron-Nucleus elastic scattering from light nuclei at around P e ~ 50 MeV/c “Coherent” P e ~ 50 MeV/c “Coherent” nuclear recoil, spin-effects, magnetic terms all ~ negligable nuclear form-factor introduces a small effect X-sections “well known”  basically “Mott-scattering” Reality: MEG beam can be tuned to give ~ 50 MeV/c e + with a max. rate of ~ 8· 10 8 e + /s at 2mA proton current with ΔP/P ~ 7% FWHM  obviously would reduce ΔP/P to achieve “monochromaticity” though at the cost of rate. Wien-filter does not work at this momentum to sufficiently separate e + from  + but a 2mm CH 2 -degrader at the collimator system in front of BTS DOES! Carbon target ρ ~ 2.1 g/cm 3 t < 1cm thick, and 10 7 e + /s Integrated X-section: 30 ° < Δθ < 120 ° & Δφ =   2.5 mbarn  ~ 1300 events/s Carbon target ρ ~ 2.1 g/cm 3 t < 1cm thick, and 10 7 e + /s Integrated X-section: 30 ° < Δθ < 120 ° & Δφ =   2.5 mbarn  ~ 1300 events/s

16 Prospects 2 months of stable data taking at the end of 2009 Improvement in sensitivity due to stable conditions: 4 * for 2009 data (analysing now): ready next month Data taking now restarting: continue at least until 2012 (no competitor) Start thinking of possibile improvements/upgrades More details at Planning R & D Assembly Data Taking now

Composizione gruppo: MEG Pisa A. Baldini 100 C. Bemporad 100 F. Cei100 C. Cerri 50 L. Galli? G. Gallucci? M. Grassi100 D. Nicolo’100 G. Signorelli100 F. Sergiampietri 80 Totale FTE (+ tecnologi?)

Pisa - Richieste 2011 MI2 K€ * fte+2.5 K€ SP = 19 K€ ME5 m.u. * fte+2 m.u. * resp =247.5 K€ Cons2K€ * fte + 20 metab.* Apparato in presa dati: Criostato + trigger + accel.= 77 K€ Inv.Analisi end user 8 K€ + crate NIM 8 K€ Richieste di personale: solo per aiuti specifici

Suddivisione per sezione Nel 2010 Totale avuti = 580/885 richiesti