Muon triggering system for the ALICE TOF cosmic tests

for the ITEP Moscow:

A.AkindinovYu.GrishukS.KiselevD.Mal’kevichM.RyabininA.SmirnitskiK.VoloshinB.Zagreev

- NIM, A387, pp. 231-234, 1997- Patent for invention of Russia, №2142175, 1999- Preprint ITEP 11 - 03, 2003- 8th ICATPP, Villa Elba, Como, 6-10 Oct., 2003- Preprint ITEP 05 - 04, 2004- PTE, appr. for publishing, May, 2004 - NIM, submitted in Sept., 2004

CBM – Russia meeting at ITEP, Nov 5th 2004

ALICE TOFCosmic Ray Test Facility

Cosmic particle

TOF modules

Muon filter

Trigger detectors

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 TOFCosmic Tests of Detector Elements

Muon Triggering System

• scintillator plate

• dimensions 15151 cm3

• 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 11 mm2 working area

ITEP

Assembling of a trigger detector

scintillator plate

WLS fibers inside round grooves

APDs

Completely functional trigger detectorfor the ALICE TOF Cosmic Ray Facility.

FEE card implemented.

ALICE TOFCosmic Tests of Detector Elements

Trigger Detector ITEP

ALICE TOFCosmic Tests of Detector Elements

Trigger Detector under Test ITEP

Beam to different places of the ‘tile’

Amplitude spectra

ALICE TOFCosmic Tests of Detector Elements

Construction of the Muon Triggering System

Phase 1: building the prototype of a mosaic trigger detectorThe work has been launched at ITEP

Assembly procedure

Processing the scintillator plates

ALICE TOFCosmic 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 APDsused in prototypes

• sensitive area size ~ 1 mm2

• gain ~ 106

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.

0 5 10 15 20 25 30 3510

20

30

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110

Fourth glueingThird glueingSecond glueingFirst glueing

Efficiency scan for 32 STARs

Eff

icie

ncy

, %

STAR number0 5 10 15 20 25 30 35

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

Time resolution for 32 STARs

Fourth glueingThird glueingSecond glueingFirst glueing

Tim

e re

solu

tion

TO

F (T

1 -

T 2

) /2

, ns

STAR number

1 m2 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 2005

3. 20 m**2 - full system - plans: ready mid 2006

Resumeon experience with 1 m**2 array of STARTs

1. Stable, repeatable characteristics2. Response to MIP – clear, stays far above the pedestal – - 100% efficiency3. 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