MICE detectors and first results. M. Bonesini Sezione INFN Milano Bicocca

Transcription

1 MICE detectors and first results M. Bonesini Sezione INFN Milano Bicocca

2 I will speak of the installed beamline PID detectors (TOFes, CKOVs, KL) and only shortly of EMR (to be built)/ the trackers (tested with cosmics only). For Lumi monitors see Ken s talk. Apologies for being at RAL virtually M. Bonesini - FAC April 2010 RAL 2

3 Accomplishments: Target Beamline PID detectors Mice Hall infrastructure M. Bonesini - FAC April 2010 RAL 3

4 ISIS 800 MeV proton synchrotron at RAL Titanium target, grazing ISIS beam p captured by quad triplet and momentum selected by dipole Followed by 5T decay superconducting solenoid (5 m long): contain p and decay m Second dipole momentum select muons ISIS MICE Hall R5.2 M. Bonesini - FAC April 2010 RAL 4

5 Particle identification: TOF, CKOV, Calorimeters Upstream Time of Flight TOF0 + TOF1 2 Aerogel threshold Cherenkov detectors p/m separation up to 360 MeV/c Beam purity better than 99.9% Downstream TOF2 EMC Calorimeter Kloe-like (KL) Lead-scintillating fiber sandwich layer (built) Electron-Muon Ranger (EMR) (to be built) 1m 3 block extruded scintillator bars Also measure muon momentum m/e separation Particle tracking Scintillating Fiber trackers Measure position and reconstruct momentum M. Bonesini - FAC April 2010 RAL 5

6 Scintillating fiber trackers Reduce transverse emittance by 10% Trackers need to measure this reduction to 0.1% precision Determine x,x,y,y and momentum High resolution on order of 1 fiber needed Design 350 mm scintillating fiber doublet layers Active area has diameter of 30 cm 5 measurement stations with 3 planes each Status: tracker setup lab 7,R1 RAL T1,T2 commisioned with cosmics M. Bonesini - FAC April 2010 RAL 6

7 Trackers Both trackers completed Cosmic ray test of tracker1 at RAL: Light yield measured 11 PE Measured resolution consistent with goal of 430 mm Efficiency 99% hit efficiencies to be installed in beam inside 4 T solenoid magnet (US) ~1m long with 5 SC coils Magnets see Mike talk for details M. Bonesini - FAC April 2010 RAL 7

8 MICE Particle ID Important to insure high muon purity for muon cooling measurement. Upstream: TOF0,1 X/Y hodoscope with 10m path, 70 ps resolution 2 Aereogel threshold Cherenkov detectors (n=1.07 and n=1.12) p/m/e separation at better than 1% at 230 MeV/c Downstream: 0.5% of m s decay in flight: need electron rejection at 10-3 to avoid bias on emittance reduction measurement TOF2 X/Y hodoscope EMC Calorimeter for MIP vs E.M. Shower (KL (built) + EMR (in future)) M. Bonesini - FAC April 2010 RAL 8

9 The upstream part (inside DSA) MICE Beamline Phase1/2 Startup TOF1,TOF2,KL CKOVa,b TOF0 Ckov counters DSA TOF0

10 Upstream : CKOVa/CKOVb Aerogel box radiator Reflector Panels (not shown) 8" PMT port CKOV PMTs (from CHOOZ, INFN Ts) M. Bonesini - FAC April 2010 RAL 10

11 Took data in MICE beamline Typical light spectrum from single PMT Muon tagging efficiency 98% M. Bonesini - FAC April 2010 RAL 11

12 EMC is not primarily intended for energy measurements: it s main role is to provide e/m separation In MICE proposal this was provided by a CKOV counter + an emcalorimeter (KL) Now it will be provided by KL + a sandwich calorimeter (EMR to be constructed) KL (KLOE-light) is a fiber spaghetti calorimeter with a design similar to the KLOE one EMR is a fully active calorimeter (10 layers) with increasing thickness M. Bonesini - FAC April 2010 RAL 12

13 Installation with TOF2 in temporary position after Q9 at RAL M. Bonesini - FAC April 2010 RAL 13

14 INFN contribution (up to 2009) was: Prototype development (INFN Ts) Final downstream platform for TOF2,KL,EMR (built&installed INFN Rm3) M. Bonesini - FAC April 2010 RAL 14

15 EMR design & Module M0 prototype KL EMR (to be built) EMR features: - 25 modules - 1 module is made of X&Y planes triangular bars - nearly 11 km of WLS fibers (1.2mm diam.) - 50 multianode PMT - 50 single pixel PMT - 28 Kg per plane (1,5 Ton totally) Movable platform Built from INFN Rm3

16 Main Steps Cutting to length done Gluing fibers (up to 20 per day) Layer Assembly Module Assembly CM26 March 2010 Slide 16

17 The problem was more serious than originally thought We have now a satisfactory design Large iron reflector between KL and EMR EMR is moved back by 50 mm Local shielding (1m) around each PMT EMR PMT axis

18 Waiting for EMR, 3 scintillator counters 10 cm wide (Taggers) have been installed behind KL to study what survives M. Bonesini - FAC April 2010 RAL 18

19 Exp trigger, upstream/downstream PID and measure of t vs RF Work in a harsh environment (high incoming particle rate, high fringe fields from solenoids, X rays from converted e - ) with good timing performances (s t ~70 ps) s pl Tof resolution can be expressed as: s t s 2 scint s N 2 PMT 2 elec M. Bonesini - FAC April 2010 RAL 19 pe s 2 pl s Some points to look to have high resolution TOFs dominated by geometrical dimensions (L/Npe) s scint ps (mainly connected with produced number of s fast and scintillator characteristics, such as risetime) s PMT PMT TTS (typically ps) + HARSH Environment (shielding from B, RF noise, high particle rate)

20 conventional X/Y scintillator structure with readout at both ends, to provide redundancy & intercalibration with inc. m problem: choice of PMTs for high incident particle rate (1 MHz) and solenoid B fringe field (B // ~ G, B perp ~ 1K G) M. Bonesini - FAC April 2010 RAL 20

21 With an external cage B field is reduced to tolerable levels for conventional R4198 PMTs (solution adopted for TOF1) for TOF2 massive box ARMCO local shielding (D0-like) solution PMT studies show solution is adequate.. M. Bonesini - FAC April 2010 RAL 21

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24 The adoption of leading edge discriminators introduces a dependence of the discrimination crossing time on the collected charge (time walk). The plots show overall distribution of the time difference between the vertical and horizontal slabs for all the counters in TOF0 without (top) and with (bottom) the time corrections. The measurements from the calibrated pixels (the peak at zero) and from the still uncalibrated pixels are clearly distinguishable. M. Bonesini - FAC April 2010 RAL 24

25 The difference between the vertical and horizontal slabs in the same station can be used also to measure the time Time resolution after the calibration: T OF0 50ps; TOF1 63ps TOF2 51ps against a 70 ps requirements (proposal/technical report) M. Bonesini - FAC April 2010 RAL 25

26 The first peak is considered as the time of flight of the positrons and is used to determine the absolute value of the time in TOF2. A natural interpretation of the other two peaks in the time of flight spectrum is that they are due to forward flying muons from pion decay and pions themselves (results have been recently published on NIM A615 (2010) 14). M. Bonesini - FAC April 2010 RAL 26

27 KL response to 270 MeV/c p beam KL energy response KL response to 250 MeV e + beam M. Bonesini - FAC April 2010 RAL 27

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32 Trackers tested with cosmics. Good performances, but installation schedule in beam is bound to solenoids delivery schedule This affects also other PID detectors, that will have to move around the MICE Hall for the different steps (re-installation problem) Quality of TOF PMTs was questionable: half of them had to be refurbished by Hamamatsu, the second half just installed on TOF0 will have to be dismounted for repair at the end of run (September 2010) -> refurbished TOF0 by beginning 2011 Still pending sync problem in DAQ event building for a fraction of events (see next slide) M. Bonesini - FAC April 2010 RAL 32

33 In part of a run, sync between TOF and KL is lost by DAQ ( pion Good file from run 1514 (250 MeV/c Bad file from same run 1514

34 440 Mev/c muon beam : muons originate mainly from decays inside the decay solenoid. (Dec 2009 data) Reconstruction of 4D emittance using TOF0 and TOF1 (x,px,y,py). Values are reconstructed within10 % M. Bonesini - FAC April 2010 RAL 34

35 N orm alised C ounts TOF0,TOF1,TOF2,KL, CKOV have been installed at RAL and calibrated. They have been used for beamline characterization and first emittances measurements P ions B 2 S can at 414 M ev /c P rotons 300 MeV/c pion beam profile in TOF0. Left : 2D beam profile C urrent in D 2 (A m p) EMR is expected for 2011 Trackers ready and waiting for solenoids Luminosity monitors have been installed A lot of activities around; first results from PID detectors available M. Bonesini - FAC April 2010 RAL 35