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02/26/2004
Target lab:
- Lingyan:
- Did another spindown with NMR measurement 6 hours apart. After correction, the lifetime for Queen Mary is 34.1 hours (UVA measured 34 hours).
- Ameya will do a spindown with NMR measurement 90min apart this weekend.
- EPR works fine. Lingyan did some improvements to remove spikes in the EPR spectrum.
- Kathy:
- Sasha made 10-turns RF coils.
- No significant reflexion found inside and outside the magnetic box.
Cell production:
- Todd:
- Pure potassium sphere and pure rubidium sphere spin up the same in 10 hours.
- Jaideep:
- 1st cell was made --> Panache is a K/Rb hybrid cell with a bigger pumping chamber.
- The target oven was redesigned to be bigger and resistant to higher temperature (about 250 C).
- Working on measuring Alkali Metal Vapor density and polarization using Faraday rotation (Circular Birefringence induced by B field).
Small Angle GDH:
- Seonho:
- Worked on Fourier transform for wall thickness analysis:
--> used a quadratic interpolation between the data point.
--> then applied the Fast Fourier Transform.
--> conclusion: it works fine to extract the wavelength, and, sinusoidal and Fourier give the same result.
- will check again with a bad wall thickness spectrum.
- Vince:
- Wall thickness analysis using the minima & maxima method is done.
- dp optimization:
* problem with the code.
* found and corrected bugs.
* 1st iteration is done.
* Nilanga looked at it and said that things don't seem right.
- Tim:
- Looking into BCM error analysis.
- BCM versus FC2: fairly linear.
- Showed Hall C bleedthrough in Hall A beam during saGDH to give an idea of correction to be applied in Spin Duality analysis.
Spin duality analysis:
- Patricia:
- Showed W peak position and width versus run for elastic kinematic: width and peak position is very stable.
- Regenerated Elastic asymmetry with same cut applied to data and simulation
* left arm average asymmetry = (4.045 +/- 0.258)% and Monte Carlo simulation gives 4.101%.
* right arm average asymmetry = (3.839 +/- 0.210)% and Monte Carlo simulation gives 4.129%.
- Jian-Ping said that the cuts are too tight for asymmetry analysis.
- The W peaks of simulation and data don't match too well: Alexandre and Jian-Ping suggested to look at the spectrometer resolution.
- When plotting Y_tg for the empty reference cell and the pol. 3He cell, the target windows don't match for the left arm however it looks good for the right arm --> have to check it.
- Plan: elastic cross section then will go back to elastic asymmetry.
02/19/2004
Target lab:
- Jian-Ping:
- talked about the task list for the target lab.
- Optical fiber 5-to-1 better without homogenizer.
- has to start planning for next 2 years budget.
- Lingyan:
- Showed spin-up (optical pumping with only 2 lasers) and spin-down curves: lifetime= 30hours (UVA measured 34hours).
- Adjusted laser temperatures to get good absorption.
- Plan: EPR set-up on Friday and lifetime measurement with NMR measurements every 6 hours during the weekend.
- Kathy:
- talked about the tests done on the magnetic box for Gen target system.
- The goal is to see the effect of the magnetic box on the RF.
- Sasha (from Temple) wrapped RF coils on wooden stands and placed pick-up coils on a stick: from this preliminary test the RF frequency seen by the pick-up coils was 18 kHz.
Small angle GDH:
- Tim:
- Left arm asymmetry check for kinematic 11: BCM asym.= 21ppm, Phys. asym.=121ppm.
- Left arm asymmetry check for kinematic 9: BCM asym.= 44ppm, Phys. asym.=-153ppm. But this kinematic need to be checked due to error bars inconsistency.
- Average of physics asym. (kin. 9, 10, 11 and 12): (-5.16 +/- 63.85) ppm.
- Vince:
- Optics reconstruction:
* started working on dp.
* talked to John Lerose about distortion in +phi_tg reconstruction: it is possibly due to a gap between the coils. John suggested that higher order elements are needed.
- Wall thickness:
* Numerical Recipes code does not give correct spectrum for a simple sinewave so abandonned this approach for now.
* Instead use signal minima & maxima as an alternative to the fit.
Spin duality analysis:
- Patricia:
- Showed elastic asymmetry generated with a cut on the elastic peak.
- After removing bad runs and short runs:
* left arm average asymmetry = (3.890 +/- 0.144)% and preliminary simulation gives 4.126%.
* right arm average asymmetry = (3.513 +/- 0.138)% but no simulation done yet for the right arm.
- The right arm asymmetries show some strange behavior that has to be investigated.
- Jian-Ping suggested to check the possible bleedthrough of Hall C in Hall A beam during Spin Duality.
- Seonho suggested to study the stability of the elastic peak position for all runs in order to check if we didn't have a problem at the time with the right magnets.
- Plan: continue elastic analysis.
02/12/2004
Target lab:
- Lingyan:
- Laser alignment is done.
- All 4 RTDs are working now but it would be good to have at least 5 RTDs on the target for temperature test.
- The spectrum analyzer is plugged in upstairs so we can not use it for now.
- Plan: spin-down during the weekend.
Small angle GDH:
- Tim:
- Left arm asymmetry check for kinematic 12.
- BCM asymmetry: 45ppm.
- Physics asymmetry: 21ppm.
- Vince:
- Phi-tg optimization:
* pretty good except central row, 1st-4th columns.
* looked at improving reconstruction: add new elements, removed elements and removed holes.
* Conclusions: No improvements. First 12 lowest elements improved reconstruction. Offset in central row present in left septum data (before optimizing).
* Nilanga checking code.
* Beginning dp optimization.
* still need to look at y-tg
- Wall thickness:
* use a Fourier transform.
* code from Numerical Recipes.
* checked with LabView --> comparable results.
* so far unable to get a quantity for wall thickness.
* plan to check results with gsl routine.
Spin duality analysis:
- Patricia:
- Used the very very last version of ESPACE (sept. 2003).
- Regenerated all asymmetries: now elastic asymmetries looks good (except no cut on elastic peak has been applied) --> sign change can be seen at configuration change.
- Asymmetries stay unchanged for all other kinematics.
- Cerenkov cut efficiency: due to the pion contamination in the shower electron sample, the true efficiency should be evaluated at the lower W of each energy.
- Plan:
* continue elastic analysis.
* finish efficiency evaluation for all detectors.
* look at asymmetry variations by changing cuts.
02/05/2004
Generalities:
- Jian-Ping:
- Talked about the conferences coming.
- Exposed quickly the GeN plan for the target.
- Reported the progress on the future laser room.
- Encountered some problems with the manufacturers for the optical fibers.
- Pointed out the lack of manpower for the preparation of the next pol. 3He experiments.
Target lab:
- Lingyan:
- One laser gives a significantly lower power for the same current setting as the others.
- Jian-Ping suggested that it may come from the calibration.
Small angle GDH:
- Tim:
- Left arm asymmetry check for kinematic 10: (0.183 +/- 0.154)E-3.
- BCM asymmetry: (53 +/- 30)ppm
- Physics asymmetry: (0.140 +/- 0.187)E-3
- Vince:
- Optics optimization:
* Now used 4 runs with raster off.
* Changed some cuts.
* Phi-tg is much better.
- Wall thickness:
* Error analysis.
* Rob suggested to use a Fourier transform to fit the wall thickness spectrum.
Spin duality analysis:
- Patricia:
- Cerenkov cut efficiency for all runs (except elastic): Jian-Ping pointed out the strange behavior in the left arm --> to be checked.
- Trigger and VDC efficiencies for electron. For VDC efficiency, should have cut on shower and preshower variables that don't contain any tracking requirements --> to be done again.
- Elastic analysis: after a lot of struggles and checks, the ESPACE version used to do the analysis seems to be the problem.
- Plan:
* Solve elastic asymmetry problem and then run the simulation.
* Go to cross section analysis.
* Trigger, VDC and lead glass electron efficiencies for all runs. Jian-Ping suggested to do the same thing with pions at the same time.
(last updated: 02/21/2004, maintained by Patricia Solvignon)