[PEPPo] Daily RC Report 6/2

[voutier at lpsc.in2p3.fr]

https://positron.jlab.org/wiki/index.php/Sat%2C_June_2%2C_2012_%28Voutier%29

Daily RC Report

Polarimeter calibration continues

Data Taking

The beam energy set at 5.5 Mev/c, the sensitivity of the Compton  
polarimeter to the orientation of the polarization of the electron  
beam was measured. As expected, we have a very strong sensitivity to  
the z-component. No real sensitivity to the x-component is observed  
while some sensitivity to the y-component is observed by the sign flip  
of the asymmetry when inserting the half-wave-plate or switching the  
polarity of the analyzing magnet. This does not seem to come from a  
beam charge asymmetry which was measured very small.

The calibration of the polarimeter at 5.5 MeV/c was achieved over the  
night and a systematic study of the linearity as function of the beam  
current was performed. Non-linearities have been observed and  
characterized and are still under .

Later today the beam energy was changed to 4.2 MeV/c for a new  
calibration point.

Hardware

After the energy change, the beam spot at T2 was found to be  
abnormally unstable. This was traced back to the power supply of the  
PEPPo spectrometer and presumably its regulation. The power supply was  
changed.

Event

The accelerator was down for about 1.5h following a tornado alarm. The  
experiment was down for 1.5h because of the spectrometer power supply.

Next 24 hours:

Saturday, 6/2 - SWING SL=Alexandre CAMSONNE

   Calibration of the polarimeter at 4.2 MeV/c
   Energy change to 6.3 MeV/c

Sunday, 6/3 - OWL SL=Jean-Sebastien REAL

   Calibration of the polarimeter at 6.3 MeV/c
   Systematic studies

Sunday, 6/3 - DAY, SL=Joe GRAMES

   Energy change to 3.22 MeV/c
   Calibration of the polarimeter at 3.22 MeV/c
   Energy change to 7.26 MeV/c


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