Transcript ppt

GLAST LAT Project
LAT Instrument Analysis Meeting– Aug 29, 2005
GLAST Large Area Telescope:
Gamma-ray Large
Area Space
Telescope
TKR Updates at SLAC
Hiro Tajima (SLAC)
Johann Cohen-Tanugi (SLAC)
TKR
[email protected]
650-926-3035
Hiro Tajima, TKR Updates at SLAC
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GLAST LAT Project
LAT Instrument Analysis Meeting– Aug 29, 2005
OUTLINE
• End-toEnd TOT Calibrations
– Summary of TOT calibration sequence.
– Charge scale distribution for 8-tower data
– Comparison between MC and data.
• TOT distribution
• Angle dependence of TOT peak
• Efficiency trending.
Hiro Tajima, TKR Updates at SLAC
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GLAST LAT Project
LAT Instrument Analysis Meeting– Aug 29, 2005
End-to-End TOT Calibration Summary
• TACK timing.
– done.
• GTFE charge injection scale.
– done.
• GTFE Threshold.
– done.
• TOT gain parameter.
– Correct thresholds were not used due to a bug in the TKR
script
• Fixed before 8-tower tests.
– Column and row number were swapped due to a bug in
LATTE tower mapping.
• Fixed before 8-tower tests.
• TKR recon.
– Wrong scale was used for “charge per MIP” parameter.
Hiro Tajima, TKR Updates at SLAC
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GLAST LAT Project
LAT Instrument Analysis Meeting– Aug 29, 2005
Charge Scale after TOT Calibrations
•
Definition of charge scale.
– Plot ratio 4.92/peak. (4.92 fC is expected for MIP)
(should be 1.0 if calibration is correctly applied.)
Before charge scale calibration
8-tower data (after fixes)
6-tower data
(after charge scale calibration)
Wrong “fC per MIP”
parameter
Johann
Tower row and column
Numbers swapped for
TOT gain parameter
Hiro Tajima, TKR Updates at SLAC
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GLAST LAT Project
LAT Instrument Analysis Meeting– Aug 29, 2005
Data/MC Comparison: TOT Distribution
• Fit parameters for data and MC are very similar
– Gaussian convolved Landau distribution function
– Peak at 4.91 : 4.92 fC
MC
– Landau width at 0.375 : 0.344
– Gaussian sigma at 0.69 : 0.69
Data
TOT charge (fC)
TOT charge (fC)
Hiro Tajima, TKR Updates at SLAC
Johann
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GLAST LAT Project
LAT Instrument Analysis Meeting– Aug 29, 2005
Angle Dependence of TOT Peak
TOT peak (fC)
• Incident angle dependence of TOT peak.
MC before
angle correction:
10% effect
MC
MC
MC after
angle correction:
<1% effect
cos
cos
DATA
8-tower data after
angle correction:
~1% residual effect
Johann
cos
Hiro Tajima, TKR Updates at SLAC
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GLAST LAT Project
LAT Instrument Analysis Meeting– Aug 29, 2005
Tower Efficiency Trending
Trend tower efficiency during I&T phase
– All I&T data sets are analyzed by the latest TkrRecon.
– FMB and FM1 shows consistent (but tiny) downward trend.
• 0.06% inefficiency corresponds to ONE strip.
Efficiency Trend
0.06%
0.04%
Efficiency change
•
TkrFMA
TkrFMB
TkrFM1
TkrFM2
TkrFM3
TkrFM4
TkrFM5
TkrFM6
0.02%
0.00%
-0.02%
-0.04%
-0.06%
Johann
-0.08%
2TWR
4TWR
6TWR
8TWR
Test phase
Hiro Tajima, TKR Updates at SLAC
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GLAST LAT Project
LAT Instrument Analysis Meeting– Aug 29, 2005
Conclusions
• Calibration procedure for TOT/threshold/charge scale is
demonstrated end-to-end.
– Improvement can be made for angle dependence of TOT
peak in data.
– TOT distributions in data and MC are very similar.
• Started tower efficiency trending.
– No major drop of efficiency observed.
– Tiny and consistent downward trend in FMB and FM1.
• Plan to trend more parameters.
– # of bad channels, thresholds, TOT parameters …
Hiro Tajima, TKR Updates at SLAC
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