1. E166 Photon Asymmetry Simulation
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E166 Photon Asymmetry Simulation
How it works
Results
Comparing to Measurements
V.Gharibyan Nov 2006 DESY

2. Photon Asymmetry Simulation How it works
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E166 Photon Case
Targets
Analytic
Integration
Monte-Carlo
Tracking
Exponential
Decay ds dW ds dW
Stot
, Stot
, Stot
V.Gharibyan Nov 2006 DESY

3. Photon Asymmetry Simulation How it works
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Explore MeV photon interaction main processes:
Iron electrons are Polarized, so the Compton scattering.
At the moment neglect polarization in Photo-effect.
V.Gharibyan Nov 2006 DESY

4. Photon Asymmetry Simulation Results
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Undulator spectra
provided by
Klaus Flotmann.
k=0.19 l = 2.54cm
V.Gharibyan Nov 2006 DESY

5. Photon Asymmetry Simulation Comparing to Measurements
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Cherenkov Multiphoton Counting Detector
Prediction is 3.64%
Measurement 3.50%
If effective threshold is 5MeV ?
V.Gharibyan Nov 2006 DESY

6. Photon Asymmetry Simulation Comparing to Measurements
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Multiphoton Energy Integrating Detector (Calorimeter)
Prediction is 3.26%.
Observed %.
V.Gharibyan Nov 2006 DESY

7. Photon Asymmetry Simulation Conclusion
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Measured and predicted numbers are pretty much close. None of them has an error to quote.
One detector (calorimeter) measures higher and the other (Cherenkov) lower than predicted asymmetry. This points the observed discrepancy
to originate from detector/simulation rather than
from original undulator spectra.
A polarized photo-effect could be considered.
V.Gharibyan Nov 2006 DESY