Muon triggering system for the ALICE TOF cosmic tests for the ITEP Moscow: A.Akindinov Yu.Grishuk S.Kiselev D.Mal’kevich M.Ryabinin A.Smirnitski K.Voloshin B.Zagreev - NIM, A387, pp , Patent for invention of Russia, № , Preprint ITEP , th ICATPP, Villa Elba, Como, 6-10 Oct., Preprint ITEP , PTE, appr. for publishing, May, NIM, submitted in Sept., 2004 CBM – Russia meeting at ITEP, Nov 5 th 2004

ALICE TOF Cosmic Ray Test Facility To separate straight tracks of high-energy muons one needs at least 3 planes of trigger detectors organized in a granular structure The mechanical farm is already built Trigger counters are under construction TOF modules may be installed in 6 different positions

ALICE TOF Cosmic Tests of Detector Elements Muon Triggering System scintillator plate dimensions 15  15  1 cm 3 two round grooves at both surfaces two WLS fibers will be put into the grooves to collect light and to concentrate it on two MRS APDs ‘Tile’ WLS fiber (Kuraray Y11) and MRS APD (by CPTA, Moscow) with 1  1 mm 2 working area ITEP

Assembling of a trigger detector scintillator plate WLS fibers inside round grooves APDs Completely functional trigger detector for the ALICE TOF Cosmic Ray Facility. FEE card implemented. ALICE TOF Cosmic Tests of Detector Elements Trigger Detector ITEP

ALICE TOF Cosmic Tests of Detector Elements Trigger Detector under Test ITEP Beam to different places of the ‘tile’ Amplitude spectra

ALICE TOF Cosmic Tests of Detector Elements Construction of the Muon Triggering System Phase 1: building the prototype of a mosaic trigger detector The work has been launched at ITEP Assembly procedure Processing the scintillator plates

ALICE TOF Cosmic Tests of Detector Elements Muon Triggering System Mosaic stricture of the trigger detector Light detection by high-gain MRS APD 2 MRS APDs per cell dense packing ensures the absence of ‘dead’ zones intrinsic noise of a single cell ~ 0.01 Hz Various kinds of MRS APDs used in prototypes sensitive area size ~ 1 mm 2 gain ~ 10 6

Parameters: FE card and input signal Ampl. 0.5 V/pC ( at 35 pF ) Noise ~ 3000 e - Res. time of coincidence circuit 10 – 40 ns Working point 51 V Thresh. 130 mV (260 fC) ~ 3.5 ph.e.

1 m 2 muon detector – beam test with MIP

Close plans for the ALICE TOF muon trigger system 1. 1 m**2 - ready ( May 2004 ) 2. 7 m**2 - plans : ready mid 2005 work currently performing at ITEP: - sc. plastic has been built by “Polimersintez” now under machining at ITEP - FEE cards constr. close to finish (next week) - MRS APDs – still under choosing latest version i.e. so far: OK - assembly/tests – winter/spring m**2 - full system - plans: ready mid 2006

Resume on experience with 1 m**2 array of STARTs 1.Stable, repeatable characteristics 2.Response to MIP – clear, stays far above the pedestal – - 100% efficiency 3. Due to geometry – can be easily arranged in large trigger array 4. Cost – 70–140 USD/cell - now For large system ( ~ 40 cells/m**2) – 2–3 kUSD/m**2 - now Clear prediction for cost reduction… Will be used for cosmic muon triggering in ALICE TOF - now Good candidate to replace RPC for high rate muon triggering Intrinsic noise – around 10** -2 Hz/cell - now could be easily reduced to 10**-3 – 10**-4 Hz/cell - now