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Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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The Time Of Flight detector of the ALICE experiment
- The role of the TOF in ALICE;
- The optimal detector choice: the MRPC;
- FRONT-END and Readout Electronics;
- Supermodule construction and test;
- The installation of the first two supermodules
- Conclusions
E. Scapparone (INFN – Bologna)on behalf of the TOF(*) GroupQM2006, Nov 15, 2006
(*) INFN and University, Bologna (Italy) – INFN and University, Salerno (Italy) – ITEP Moskow (Russia) - Kangnung University (South Korea)
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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TPC + ITS (dE/dx)
/KK/p
e /
0 1 p(GeV/c)
Particle Identification in ALICE
0 1 2 3 4 5 p(GeV/c)
TOF (100 ps)
/KK/p
e /TOF ( 50 ps)
/KK/p
e /
TOF (3.7 m from the beam pipe)TOF (3.7 m from the beam pipe)
ITSITS
HMPIDHMPID
/KK/p
TPCTPC
0 1 2 3 4 5 p(GeV/c)
HMPID
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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TOF requirements:
Large array to cover the ALICE barrel (~150 m2)Time resolution σ < 100 ps High efficiency, ε > 95%High segmentation: few thousands of particles per unit of rapidity expected in Pb-Pb collision at s = 5.5 TeV/nucleon pair
ALICE choice: a detector based on MRPC, segmented in ~157,000 channels, (3.5 x 2.5) cm2 area
√
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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M = p ((t2 c2 /L2 )-1)1/2
σTOF = 80 ps ; B = 0.5 T
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Combined PID Performance Efficiency/Contamination
Kaon PID (the most difficult case...)
ITSTPC
TOF(*)(120 ps)
p (GeV/c) p (GeV/c) p (GeV/c)
(C : CK : Cp = 0.75 : 0.15 : 0.1)
Higher efficiency & Lower contamination wrt individual detectors
p (GeV/c)
Combined PID ITS & TPC & TOF
(*) very conservative
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A TOF SuperModule in the Space Frame
2 crates /side157248 pads, total sensitive area: ~150 m2
18 Supermodules, each made of 5 modules: 2 external (19 strips), 2 intermediate (19 strips), 1 central (15 strips)
7.4 m
Readout performed bytwo VME Crates/Side
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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Central module0º
3.2º
4.3º
5.3º
0.5º 1.6º 2.7º 4.8º3.7º
1º
2.1º
15.30 cm8.5 cm
70138209276349415492
6.3º
7.4º
5.9º 6.9º 7.9º
99 cm114 cm
27.8º28.7º 29.6º 30.5º 31.5º 32.3º 33.3º 34.2º 34.9º 35.8º 36.6º 37.4º 38.3º 39.2º 40.1º 40.8º 41.6º 42.4º 43.1º 43.9º
173 cm
178.2 cm
Outer module
44.3º
27.3º 28.2º 30.1º 31.0º 32.8º 33.7º 34.6º35.4º 36.3º37.1º 38.8º 39.6º 40.4º 41.2º 42.0º 42.8º
43.5º
37.9º31.9º29.2º
8.2º 9.3º 13.4º12.4º11.4º10.3º
8.7º
9.8º
10.8º
11.9º
12.9º
13.9º
14.9º
16º
17º
18º
19.1º
20.1º
21.1º 23º
22.1º
23.9º 24.9º 25.9º 26.8º
147 cm
134.30 cm
27.3º
14.5º 15.5º 16.5º 17.5º 18.5º 19.5º 20.5º 21.5º 22.5º 23.4º 24.4º 25.4º 26.3º
Intermediate module
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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Cross section of a double-stack MRPC strip
2 rows of 48 readout pads (3.5 x 2.5 cm2)
Active strip length = 120 cm
Differential signal to FEA card
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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-
Produced up to now ~1550 strips ~ 95 % of the total MPRC production
MRPC CONSTRUCTION AND TEST IN BOLOGNAMRPC CONSTRUCTION AND TEST IN BOLOGNA
- Signal connector soldering test; - Gap size test ;
- Glass test;
- HV test;
- Cosmic test (sample);
Several quality assurance testsSeveral quality assurance tests::
9191 MRPC strips /SM to be produced = MRPC strips /SM to be produced = 16381638
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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TOF front end electronics: 6552 FEA TOF front end electronics: 6552 FEA cardscards
LV
To LTM
- Input stage (and following) fully differential;
- Adjustable input resistance ( 30 Ohm – 100 Ohm);
- Power: 40 mW/channels (to be compared with 400 mW/channels of the COTS amplifier);
- Nice matching with detector capacitance ( 30 pf );
- LVDS Output signal, compatible with HPTDC input
3 NINO ASICs (8 ch) /card
The benefit of the ASIC:
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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TOF Electronics: 2 VME CRATES @ each SM TOF Electronics: 2 VME CRATES @ each SM sideside
TRMTRM
TRMTRMTRM
TRMTRMTRMLTM DRM
TRMTRM
TRMTRM
TRMTRMTRM
TRMTRM
CPDMLTMDRM
TRMTRM
- Pulser to MRPC
- Clock distribution
TRMDRM
30 High Performance
TDC Chips
- FEA LV monitor- FEA thresh. set & monitor- FEAC temperature monitor- FEA OR signals for trigger- Wake up to TRD
LTMLTM
CPDMCPDM - VME master - TRM readout
- DAQ (DDL) - L0,L1,L2 (TTC)
- Slow control
Crate left Crate right
The chips contained in these boards were carefully tested in radiation (PSI, Louvain, Legnaro) and magnetic (CERN) enviroments.
Taking advantage of the very fast time response, TOF partecipates to the ALICE L0 trigger ( T < 800 ns sfter the collision)
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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An example: TRM (TDC Readout Module): 240 channels
Leading and trailing edge measurements signal width (TOT) for time slewing correction
Each TRM is equipped with 10 piggy-backs. Each piggy-back contains 3 HPTDC ASIC chip ( 8 channels, 25 ps intrinsic resolution)
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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Time slewing correction is mandatory to get extremely goodtime resolutions.TOT is a good charge substitute.
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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Test beam of single strips E
ffic
ien
cy
Tim
e re
solu
tio
n(
ps)ε > 99.9 %
average ~ 50 ps
Gas mixture: C2F4H2(90%) – SF6 (5%) – C4H10(5%)
Similar results obtained when strips are inserted inside the modules
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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Ageing study:
Total charge = 14 mC/cm2
Charge/event = 2 pC
7 *109 events /cm2 @ 50 Hz/cm2
T=1.4 108 sec = 1620 days Pb-Pb run
Time(min)
two MRPC strips irradiated at GIF
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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GIF results: No current increase
Source on
Source off
Source on
Source off
I (A)Flow = 1.4 cm3/s
The gas going to the chamber 2 was bubbled through water for some
time of the exposure
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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GIF results
No ageing effect measured at PS
Working voltage = 13 kV
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TOF Modules moved to CERN Cosmic Facility
MODULE 5
MODULE 1
MODULE 2
MODULE 3
MODULE 4
Scintillator Trigger
Modules are tested with the same electronics, service (HV+LV) and cables used in the experiment
Scintillator Trigger
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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-
SUPERMODULE CABLINGSUPERMODULE CABLING
~750 cables/Supermodule
Read out Crate Read out Crate
Signal cablesLV
FEAs
SM 1 during the cabling
HV
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AFTER CABLING: START A NEW SET OF TESTSAFTER CABLING: START A NEW SET OF TESTS- Gas system. - Cooling system test - pipe tightness, cooling test, temp monitor;
- HV test up to 4000 V;
- Power on the LV for crates ( 3.3 V ) + FEAs ( 2.5 V) + Vth measurement;
- New Pulser test (a first pulser test on each module done when modules arrive at CERN );
- Readout checks;
- Slow control test, Data on Dim server, PVSS control.
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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Installing the first TOF Supermodule
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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Oct. 5, 20062 TOF SMs inserted
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CONCLUSIONS
All productions (MRPCs, mechanics, electronics) well in progress.
Installation of first 2 SM in July and August (20/7-2/8!!!??) will be “critical” test (as usual when you install “first” pieces.... + service ready?? + very short time window!)
We are confident to have 2 (already inserted) + 8/9 SM assembled in January.
Installation time @ the pit could be critical!
- MRPC is an optimal choice to achieve a time resolution below 100 ps with high efficiency on a highly segmented detector (> 157,000 ch);
-Test beam, radiation and cosmic tests gave very good results in terms of time resolution, efficiency and ageing;
- MRPC strips production and front end + read out electronics delivery being completed;
- First and second Supermodule of the ALICE TOF succesfully installed;
- The second TOF installing period is planned for May 2007.
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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RISERVE
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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DISMOUNTING MODULES FROM COSMIC SETUP
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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MOUNTING MODULES ON THE ASSEMBLY BENCH
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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Module construction
30% modules assembly February July 2006
100% modules construction December 2006 May 2007
SuperModules Installation (new ALICE installation schedule)
Start installation SM [Stage 1] March July 2006
End installation ( 2 SM) [Stage 1] July August 2006
TOF production milestones :
SM 50% (9 SM) ready for installation August December 2006
SM 100% (18 SM) ready for installation March August 2007
With the present ALICE installation schedule we foresee to install in
February 2007 ~ 10 SuperModules.
Electronics
TRM+Crates+LV 30% production Nov. 2005 December 2006
TRM+Crates+LV 100% production Oct. 2006 February 2007
DRM+Trigger Start production Nov. 2005 March 2006
DRM 30 % production Feb. 2006 December 2006
DRM 100 % production July 2006 February 2007
TOF construction (installation) schedule (Notice that, e.g., February = 28/02, April = 30/04, July = 31/07, ….)
Notes : i) One complete order for TRM +Crates+ LV system
ii) One complete order for DRM + Trigger system, to the
same company as for TRM+ Crates + LV system
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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98.4 %
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- Module box + honeycomb production(first company, BERCELLA) Completed within this summer
-Interface card production Completed within this summer (second company, ELTOS )
- Interface card assembly on honeycomb (third company, RAV) Completed within Dec. 06
- 1st Supermodule modules tested, mechanic structure mounted, cabling completed. - 2nd Supermodule modules in the Cosmic test facility at CERN - 3rd Supermodule working on the assembly
Module production and assembly:
Supermodules status
Honeycomb
Module box
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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LTM (Local Trigger Module) 4/Supermodule TOTAL = 72
Production 5 produced and tested OK for 1° SMschedule 4 expected within Jun 06 OK for 2° SM 32 expected within Sep 06 40 expected within Nov 06
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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CPDM (Clock and Pulser Distributor Module): 1 per 2 SMs TOTAL = 36
Production 2 produced and tested schedule 7 expected within Jun 06 (OK for 4 SMs)
Da mettere foto piu’ recente....
CLKPulser
TOF Standalone PID (80 ps res. as in the PPR)
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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GIF resultsNo current increase
Source on
Source off
Source on
Source off
I (A)
No current increase
E. Scapparone RPC2003
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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Chemical analysis (Chromatography) of the outgoing gasfrom both MRPCs (CH1, CH2) by CERN EST/SM-CP : measured concentration of Fluorine under the limit of
detection (0.02 ppm), I.e. no trace of HF in the samplesppm
- No sign of degradation;
- No increase of dark current;
- No degradation in efficiency;
- No degradation in time resolution;
E. Scapparone RPC2003
- Active detector volume is 2% of the total volume of the gas box;- Diffusion for the gas exchange between strip and the surrounding gas.
Nov 15, 2006 The TOF detector of the ALICE experiment E. Scapparone
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POSITION SCAN ACROSS BOUNDARIES
Sharing of charge between neighbouring pads causes :
Global efficiency loss due to boundaries < 2%
Global double hit probability ~15%
Deterioration in resolution at the bordersCould use algorithm like average, pulse height weighted average etc..
Sharpness of boundaries depends on :
Threshold/dynamic range of charge spectrum
Size of footprint of avalanche on pickup pads