Final Results from the MEG Experiment and the Status of MEG-II and Mu3e

Transcription

1 Final Rsults from th MEG Exprimnt and th Status of MEG-II and Mu3 Francsco Rnga INFN Roma BLV Clvland, May

2 LFV in muon dcays µ γ µ µ 2

3 LFV in muon dcays µ γ µ µ A. D Gouva & P. Vogl Prog.Part.Nucl.Phys. 71 (2013) 3

4 Exprimntal Signatur of µ -> γ µ + + Positron and photon ar monochromatic (52.8 MV), back-to-back and producd at th sam tim; γ Accidntal Background DOMINANT ~ Rµ 2 µ µ Radiativ Muon Dcay (RMD) µ ν ν ν γ γ ν 4

5 Ingrdints for a sarch of µ -> γ Rconstruct th Rlativ Angl + Rconstruct th Positron Enrgy γ µ + Rconstruct th Rlativ Tim Rconstruct th Photon Enrgy 5

6 Th MEG Exprimnt Rconstruct th Rlativ Angl + Rconstruct th Positron Enrgy LX calorimtr 16 Drift Chambrs in a magntic fild LX γ µ + DC Rconstruct th Rlativ Tim TC 30 scintillating bars for timing & triggr Rconstruct th Photon Enrgy 6

7 Bam & Dtctors Th most intns DC muon bam in th world (3 x 10 7 PSI, Switzrland) : 3.5 x µ on targt, BR(µ -> γ) < 5.7 x : 7.5 x µ on targt, rsults prsntd hr 800l LX dtctor rad out by 846 PMTs Eγ Rsolution ~ 1.9% 7

8 Bam & Dtctors 16 Drift Chambr moduls: σ R ~ 300 µm, σ Z ~ 1 mm Vry light (~ 10-3 X 0 ovr th whol spctromtr) 30 scintillating bars (Timing Countrs) ~ 60 ps positron tim rsolution E Rsolution ~ 300 kv Tγ Rsolution ~ 130 ps 8

9 Liklihood Analysis Liklihood analysis of 5 discriminating variabls (E,Eγ, θγ,φγ,tγ): - yar-by-yar and vnt-by-vnt PDFs - carful tratmnt of corrlations (from wll undrstood gomtrical ffcts) Accidntal Background PDFs ar fully dfind from data sidbands: vry solid dtrmination of th (largly) dominant background Signal and radiativ dcay PDFs by combining th rsults of th calibration procdurs Normalization from th obsrvd numbr of µ -> ν ν and RMD 9

10 Rsults (I) NACC = 7684 ± 103 NRMD = 663 ± 59 NSIG (bst fit) = -2.2 Magnifid signal (BR = 4 x ) BR < 4.2 x 90% C.L. Eur. Phys. J. C76 (2016) 10

11 Rsults (II) Toy MC snsitivity Mdian UL = 5.3 x DATA 11

12 Th MEG-II Exprimnt Largr LX volum with finr light dtctor granularity Highr bam intnsity 7 x 10 7 µ/s Uniqu-volum Drift Chambr RMD Vto Scintillator Til TC 12

13 MEG-II Highlights - Th LX Calorimtr MEG W dvlopd larg-ara (12x12 mm 2 ), UV-snsitiv MPPCs to covr th innr fac of th LX calorimtr Bttr Rsolution, bttr pil-up rjction Th dtctor just ntrd th xprimntal ara, rady for a first round of calibrations MEG-II σe ~ 1%, σposition ~ 2/5 mm (x,y/z) 13

14 MEG-II Highlights - Th Timing Countrs 5mm-thick Scintillator Tils rad out by 3x3 mm 2 SiPM 1/2 sctor (1/4 of th full systm) alrady took data at PSI 1 sctor alrady built, final assmbly to b compltd by this summr σt ~ 35 ps 14

15 MEG-II Highlights - Th Drift Chambr > 50% of th chambr has bn wird, aftr having solvd svr problms of wir fragility in not dry nough nvironmnts Expctd to b wird and sald by th nd of th yar σe ~ 130 kv, σangls ~ 5 mrad, 2x largr positron fficincy 15

16 MEG-II Highlights - RDC, DAQ, Triggr RMD Vto 50% of acc. background photons com from RMD w/ positron along th bam lin Can b vtod by dtcting th positron in coincidnc with th photon A nw dtctor (LYSO + plastic scint.) alrady built -> 16% bttr snsitivity Triggr and DAQ will b intgrat in a singl, compact systm (WavDram TDAQ) Also provids powr and amplification for SiPM/MPPC 16

17 Expctd Snsitivity MEG-II is xpctd to start taking data with th full dtctor nxt yar x10 improvmnt in snsitivity w.r.t. MEG 4 x in 4 yars 17

18 Th Mu3 Exprimnt 18

19 Signal and Background + µ positrons and 1 lctron producd at th sam tim, in th sam plac, with Minv = Mµ - Accidntal Background (.g. 2 µ dcays + Bhabha) µ + + µ νν Muon Dcay (RMD + IPC) DOMINANT ν µ ν ν ν 19

20 Mu3 concpt Silicon trackr in a solnoid + scintillators for timing 50 µm HV-maps µm fibrs + 1x1 mm 2 SiPM 5 mm thick tils + 3x3 mm 2 SiPM Phas-I: + Nw compact bam lin for a quick switch btwn MEG & Mu3 Phas-II: - Nw high intnsity muon bam lin (HiMB) 20

21 Status MuPix7 HV-maps (MuPix): pixl prototyps alrady built and tstd 20 mm modul prototyps in 2017 modul production in Scintillating fibrs: Succssful tsts of fibrs and SiPM (700 ps singl fibr rsolution) Nw radout chips rcivd in Jan Scintillating tils: Tils and radout ASIC succssfully tstd < 100 ns rsolution Modul prototyps in

22 Expctd Snsitivity Data taking xpctd to start ~

23 Conclusions Both MEG and Mu3 ar on track for a furthr stp forward in th sarch for chargd Lpton Flavor Violation Within th nxt 5 yars, significativ improvmnts in th currnt limits or (hopfully) a discovry! 23

24 Backup 24

25 Targt hol rconstruction Δx = 0.2 ± 0.1 mm 25

26 Liklihood plots 26

27 Normalization 27

28 Triggr and DAQ FPGA basd triggr systm + (sinc 2011) multipl buffr: - Bam intnsity x accptanc Hz - XEC Enrgy E > 45 MV Hz - -γ Timing Tγ < 10 ns.10 2 Hz - -γ Angl 10 Hz Full digitization of all radout channls for offlin analysis: - custom digitization chip (DRS4) 28