Transcript ppt
Gamma-ray Large Area
Space Telescope
PDU Voltage
Noise Dependence
(Very Preliminary)
Claudia Cecchi
Stefano Germani
Monica Pepe
INFN Perugia
Instrument Analysis Meeting
April 21, 2006
GLAST LAT Project
IA Meeting, April 21, 2006
Data Files
We used data from the following runs:
27V-supply
• 077002818 36-sec cosmic with 5 KHz fixed f external trigger
• 077002819 36-sec cosmic with 6.5 KHz fixed f external trigger
• 077002820 36-sec cosmic with 1 KHz random f external trigger
• 077002821 36-sec cosmic with 3KHz random f external trigger
• 077002822 36-sec cosmic with 5KHz random f external trigger
• 077002823 36-sec cosmic with 5KHz random f external trigger
29V-supply
• 077002837 36-sec cosmic with 5 KHz random f external trigger
• 077002838 36-sec cosmic with 10 KHz random f external trigger
We used SVAC and Merit variables !!!
C. Cecchi - S. Germani – M. Pepe
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GLAST LAT Project
IA Meeting, April 21, 2006
Event Selection (Tracker Study)
We want to select only noisy events therefore we ask for:
• External Trigger Only
– GemConditionsWord == 128
• No reconstructed Tracks
– TkrNumTracks == 0
• No Energy in the Cal
– CalEnergyRaw == 0
• No ACD Hits
– AcdTileCount == 0 && AcdRibbonCOunt == 0
Then we compute the fraction of noisy events which have
Hit Strips:
Tower Occupancy: TkrTotalHits[tower] >0
Layer Occupancy: TkrTotalHits[tower][layer][view] >0
C. Cecchi - S. Germani – M. Pepe
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GLAST LAT Project
IA Meeting, April 21, 2006
Noisy Events /EventSelected
27V Supply
12 13 14 15
8
9
10 11
4
5
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7
0
1
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C. Cecchi - S. Germani – M. Pepe
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GLAST LAT Project
IA Meeting, April 21, 2006
Noisy Events /EventSelected
29V Supply
12 13 14 15
8
9
10 11
4
5
6
7
0
1
2
3
C. Cecchi - S. Germani – M. Pepe
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Noisy Events /EventSelected
GLAST LAT Project
27V – 29V Comparison
IA Meeting, April 21, 2006
12 13 14 15
8
9
10 11
4
5
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7
0
1
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GLAST LAT Project
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Noisy Events /EventSelected
27V–29V Comparison (Zoom)
C. Cecchi - S. Germani – M. Pepe
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GLAST LAT Project
IA Meeting, April 21, 2006
Noisy Events /EventSelected
Layer Structure Tower 1 (Typical)
C. Cecchi - S. Germani – M. Pepe
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GLAST LAT Project
IA Meeting, April 21, 2006
Noisy Events /EventSelected
Layer Structure Tower 4
One Layer with High
Occupancy (Not All Runs)
C. Cecchi - S. Germani – M. Pepe
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GLAST LAT Project
IA Meeting, April 21, 2006
Noisy Events /EventSelected
Layer Structure Tower 5
One Layer with
High Occupancy
C. Cecchi - S. Germani – M. Pepe
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GLAST LAT Project
IA Meeting, April 21, 2006
Noisy Events /EventSelected
Layer Structure Tower 13
Two Layers with
High Occupancy
C. Cecchi - S. Germani – M. Pepe
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GLAST LAT Project
IA Meeting, April 21, 2006
Conclusions
• Tracker
– No Noise dependence from PDU Voltage (Up to Now)
– We need to understand better
• The Layers structures
• The differences among different runs and run
configurations
– We may need some improvements to the Event Selection
– We could change noise definition counting the number of
hit strips in noisy events
• CAL noise analysis
– To Be Done
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