General Meeting Summary 4/9/15
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PWO CRYSTAL TESTS - TRANSMITTANCE
- Labeling of the crystals
- Spring 2014: crystal #1-10 (results below are from measurements performed after the Idaho irradiation tests)
- December 2014: crystal #11-15 (had not been measured before)
- Longitudinal Transmittance
- Crystal #14 has strange behavior above ~500 nm; this observation does not seem to be a feature of the experimental setup
- Crystal #12 also shows differences in transmittance from the other crystals when looking specifically at wave lengths 370 nm and to some extent 420 and 500 nm
- Note that crystal #9 longitudinal transmittance is consistent with the other crystals. This is different from what is observed for the transverse transmittance
- Transverse Transmittance
- Crystal #9 transmittance is lowest
- Crystal #8 behavior is different from the other crystals
- General result from this transmittance test: ~20% of the entire set of crystals does not meet specifications
- Additional observations regarding and tests with the crystals returned from the Idaho irradiation tests (#1-10)
- Some of the crystals seem to retain a brownish color, in particular crystal #2 (this is one of the crystals being sent to Rainer)
- Test of curing system - difficult to reach a conclusion
- ACTION ITEM: make a table of all crystals with transmittance results at specific wavelengths, e.g., 370 nm, 420 nm, and 500 nm
- Crystals to be sent to Rainer: #2, 3, 6, 8, and 9
- Shipping expected by 4/10
TCS WITH NPS LOI
- Uses NH3 target, two NPS type detectors to detect the lepton pair, and a combination of tracker (~3mm scintillating fiber) and hodoscope to detector the recoil protons
- Initial simulations have been carried out and geometry of experimental setup has been determined. Note that the detector configuration in Hall C is flexible and can be optimized, i.e., detector placement
- Low momentum protons
- Acceptance: studies ongoing to estimate the effect of target high field on proton deflection - implementation of magnetic field maps in the simulation. Initial studies show that angle is on order 1-2 degrees and so protons will make it out of the target
- Reconstruction of the recoil proton - impacts resolution. Ongoing studies to parameterize the acceptance to estimate the impact on the data.
- TCS event generator
- Based on VGG model; modifications include options for electron or real photon
- Initial results show a ~20% transverse target spin asymmetries
- Fits for physics case have been started. To estimate the impact of the data on these fits need: 1) error bars, 2) luminosity per day, 3) target length, 4) acceptance for the desired binning (limited theta for a given phi angle may have an impact on the projected asymmetry)
- uncertainty sources include statistics and bin width. Suggested bin width in t is less than 0.2 GeV/c^2 since the cross section depends strongly on t
ITEMS FOR NEXT MEETING:
- TCS LOI for PAC43
- Crystal studies at JLab and Giessen
- Other...
NEXT MEETING: THUR., 30 APRIL 9:00 AM (EST)