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µicroMegasMicroMEsh GAseous Structure
Muons Atlas Micro Megas Activity
Faruk DiBLEN
Cern-TR Meeting
12.08.20091
What is Micromegas?
Invented in 1995* by Giomataris and Charpak (1992, Nobel Prize, Multiwire proportional chamber)
Two-stage parallel plate avalanche chamber
Narrow amplification gap defined by the anode plane and a cathode plane
High gain gaseous detector
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Micromegas detectors for the CAST experiment
The CAST experiment is designed to study the possible emission of axions from the Sun's core.
Temporal projection chambers (TPCs) for the T2K experiment
Three TPCs for the Japanese T2K neutrino oscillation experiment
TPC-based trajectograph for future electron colliders
Cylindrical detector for the CLAS12 experiment
Neutron flux monitor for the NTOF experiment
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TestBeamSparks will be a problem in SLHC conditions with today’s Micromegas detectors
Standard bulk detectors will not handle the neutron and hadron flux at forward ATLAS conditions sparks, dead time,damage the detector if persistent
Possible solutions
– Resistive films
– Segmented mesh
– Double amplification
The Saclay group decided to realise an R&D on resistive films on
small prototype (10 cm2) detectors
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Resistive Technology
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Spark Measurement
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TestBeam Data
Data Structure
Binary data
8 detector data in same file
Words of 4 bytes (32 bit)
Run Header
Events
Run Footer
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Run Header
1st: Run header start-flag
Run number
Date in the format Date=Year*10000 + Month*100 + Day */
Date offset: (msec from absolute start of time (1904) to the first msec of current date
Startime: timestamp of run start. Because of precision problems it is defined as: absolute(timestamp of run start) – Date offset.
Run type (0,1,2,3,… data, calibration , pedestal, background …)
Magnetic field
Magnet Gas
Detector’s number
HV1 (drift)
HV2 (mesh)
Micromegas gas (% of isobutane)
Run header end-flag
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Event Structure1st: Event start-flag
Event ID (DAQ)
Event’s timestamp ( from date offset )
A trigger counter
Number of ADC data words.
Number of channels
Strip data format: ndata words of 32 bit.
Bit 0-11 is the strip charge
Bit 12-22 is the strip ID (DECODING ???)Bit 30 is valid flag Bit 31 is overflow flag Bits 23-29 are reserved
i. Word 1
ii.Word 2
.
.
Event end-flag
Next Event17
Run Footer
1st: Run footer start-flag Total number of events
End time – from date offsetRun footer end flag
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Software
Software(c/c++)
Map1
Map2
Map3
Map4
Map5
Map7
Map6
Map8
Detector order
Analysis data file
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ProblemsExample1:
Strip: 93 Data: 62 vld : 1 ovf : 0
Strip: 94 Data: 63 vld : 1 ovf : 0
Strip: 95 Data: 45 vld : 1 ovf : 0
Strip: 0 Data: 0 vld : -1880988508 ovf : 126 NON-VALID strip found...
Strip: 0 Data: 0 vld : -1880988508 ovf : 126 NON-VALID strip found…
Example 2:
Strip: 65 Data: 32 vld : 1 ovf : 0
Strip: 66 Data: 22 vld : 1 ovf : 0
Strip: 67 Data: 27 vld : 1 ovf : 0
Strip 68?
Strip: 69 Data: 21 vld : 1 ovf : 0
Strip: 70 Data: 26 vld : 1 ovf : 0
Strip: 71 Data: 19 vld : 1 ovf : 0 21
Example 3:
Strip: 94 Data: 67 vld : 1 ovf : 0
Strip: 95 Data: 84 vld : 1 ovf : 0
Strip: 95 Data: 84 vld : 1 ovf : 0
Strip: 50440304 Data: -1073751624 vld : -1809429542 ovf : 50440384 NON-VALID strip found...
Example 4:
Strip: 94 Data: 39 vld : 1 ovf : 0
Strip: 95 Data: 39 vld : 1 ovf : 0
Strip: 95 Data: 39 vld : 1 ovf : 0
Strip: 0 Data: 68 vld : 1 ovf : 0
Strip: 0 Data: 68 vld : 1 ovf : 0
Strip: 1 Data: 70 vld : 1 ovf : 022
Run Header (run info)
#############RUN INFO#################
Run number : 5117
Run date : 20090609
Run start time : 75063
Run type : 0
Magnetic Field : 94000
Magnet Gas : 0
HV1 : 500385
HV2 : 500000
Gas : 50
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Event Header
###############EVENT INFO######################
Event ID : 1
Event time : 75245334
Run type : 0
Nwords : 96
Counter 1 : 11
Counter 2 : 387
...
Counter 8 : 0
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Event Header##############EVENT INFO######################
Event ID : 1
Event time : 75245334
Run type : 0
Nwords for detector 1 : 96
Nwords for detector 2 : 95
Nwords for detector 3 : 93
…
Nwords for detector 8: 96
Counter 1 : 11
Counter 2 : 387
...
Counter 8 : 0
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Reading Data
Read Run Footer
Read events
Read strip id, charge, validity, overflow
For each event check end of event
If event ends goto next event
Check end of file for every words
If run footer is found finish reading
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StripsFind Strips which are not exist
Number of strips for detector 1 BEFORE correction is 95
In detector 1 Strip 68 is missing...
Number of missing strips is 1
Number of strips for detector 1 AFTER correction is 96
************************************************************
Number of strips for detector 2 BEFORE correction is 96
Number of missing strips is 0
Number of strips for detector 2 AFTER correction is 96
...
*************************************************************
Number of strips for detector 4 BEFORE correction is 93
In detector 4 Strip 30 is missing...
In detector 4 Strip 89 is missing...
In detector 4 Strip 92 is missing...
Number of missing strips is 3
Number of strips for detector 4 AFTER correction is 96
Set strip charge value to -1 if strip is missing
Set Nwords28
Correction Example 1:
Corrected Det : 1 Strip : 66 cntr : 66 data : 22
Corrected Det : 1 Strip : 67 cntr : 67 data : 28
Corrected Det : 1 Strip : 68 cntr : 68 data : -1
Corrected Det : 1 Strip : 69 cntr : 69 data : 21
Corrected Det : 1 Strip : 70 cntr : 70 data : 26
Example 2:
Corrected Det : 4 Strip : 28 cntr : 28 data : 10
Corrected Det : 4 Strip : 29 cntr : 29 data : 21
Corrected Det : 4 Strip : 30 cntr : 30 data : -1
Corrected Det : 4 Strip : 31 cntr : 31 data : 6
Corrected Det : 4 Strip : 32 cntr : 32 data : 46
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Decoding
Detectors(0-7):
0 1 2 3 4 5 6 7
Read map files for 8 detectors
Status: 1
Strips:
3 1 7 5 11 9 15 13 19 17 23 21 27 25 31 29
30 32 26 28 22 24 18 20 14 16 10 12 6 8 2 4
35 33 39 37 43 41 47 45 51 49 55 53 59 57 63 61
62 64 58 60 54 56 50 52 46 48 42 44 38 40 34 36
67 65 71 69 75 73 79 77 83 81 87 85 91 89 95 93
94 96 90 92 86 88 82 84 78 80 74 76 70 72 66 68
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Detector order file
Map file
Decoded stripsBefore decoding
Corrected Det : 0 Strip : 0 cntr : 0 data : 41
Corrected Det : 0 Strip : 1 cntr : 1 data : 44
Corrected Det : 0 Strip : 2 cntr : 2 data : 48
Corrected Det : 0 Strip : 3 cntr : 3 data : 52
Corrected Det : 0 Strip : 4 cntr : 4 data : 50
Corrected Det : 0 Strip : 5 cntr : 5 data : 42
Corrected Det : 0 Strip : 6 cntr : 6 data : 36
After decoding
Decoded Det : 0 Strip : 2 cntr : 0 data : 48
Decoded Det : 0 Strip : 0 cntr : 1 data : 41
Decoded Det : 0 Strip : 6 cntr : 2 data : 36
Decoded Det : 0 Strip : 4 cntr : 3 data : 50
Decoded Det : 0 Strip : 10 cntr : 4 data : 54
Decoded Det : 0 Strip : 8 cntr : 5 data : 47
Map for first 4 strip
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Decoded strips 1st strip 2nd strip 3th strip 4th stripStrip before decoding 3 1 7 5
References
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-Status Report of the Saclay Telescope in June MAMMA Testbeam Micromegas Weekly Meeting
-Upgrade of the ATLAS muon chambers for the sLHC CEA/IRFU/SEDI M. Boyer, J. Derré, E. Ferrer-Ribas, A. Giganon, I. Giomataris, S. Herlant, F. Jeanneau ,WG1 Meeting - 21/01/2009
-Micromegas in a bulk Nuclear Instruments and Methods in Physics Research A 560 (2006) 405–408
-Micromegas, a multipurpose gaseous detector Nuclear Instruments and Methods in Physics Research A 478 (2002) 26 –
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THANKS!
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