Updates October 29 2015
Xiaqing Li
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4He
Compton data analysis
• Formula for the extracted differential cross section:
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χY: extracted yield (from data and simulation)
fabs : correction factor for target absorption (from NIST XCOM database)
Nγ : number of incident photons (from 5-paddle system, which gives beam flux info.)
κ : target thickness [nuclei/cm2]
Ωeff: effective solid angle (from Geant4 simulation)
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To extract the photon yield:
Extract lineshapes from scattering data
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Plot ADC and TDC spectrum
Set calibrations to get energy and time of flight (ToF) spectrum
Apply energy and timing cuts on energy and ToF spectrum
Apply empty subtraction
Get convoluted simulation response function
• Requires the most accurate detector and target geometry info.
Fit lineshape from data to the simulation response function
Calculate the yield
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Calculation details for other factors
• fabs
• The fraction of photons attenuated by the target
• The average absorption over the target length
• Absorption correction factor
• Ωeff
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