[PEPPo] Daily RC Report 6/5

[voutier at lpsc.in2p3.fr]

https://positron.jlab.org/wiki/index.php/Tue%2C_June_5%2C_2012_%28Voutier%29


'''Daily RC Report'''


''Positron production running''


'''Beam'''

The beam energy was tuned up to 8.28 MeV/c, a performance for this 1/4  
cryomodule. The collection of particles produced at 4.2 MeV/c was  
optimized with a degraded electron beam using S1 and S2 solenoides.

'''Data Taking'''

The data taking for the first positron data point at 4.2 MeV/c on the  
1 mm production target progressed smoothly all over the night and day  
shifts. Statistics was accumulated and the first asymmetry plots as  
function of the photon energy have been obtained.

http://opsweb.acc.jlab.org/CSUEApps/elog/entry/1790493

The energy dependence behaviour as well as the sensitivity to the  
magnet polarity and the half-wave-plate are consistent with  
expectations.

'''DAQ'''

Timing adjustement of the coincidence window and the DFC trigger have  
been performed, particularly to recover the 511 keV peak in crystal 5  
which signs the presence of positrons

http://opsweb.acc.jlab.org/CSUEApps/elog/entry/1790285

'''Hardware'''

It has been observed over the shifts that the polarity change of the  
analyzing magnet couples to a small change in the dipole current. This  
apparent cross-talk between the two magnet power supplies is inferred  
from the tranducer read-out. At this time, it is not established  
whether this is a read-out issue or a real current change. The data  
taking over the owl shift will be performed at fixed magnet current,  
and a test at 5.5 MeV/c beam energy will be done tomorrow day to  
establish whether this change is real.


Next 24 hours:

Tuesday, 6/5 - SWING SL=Alexandre CAMSONNE
    Positron Data taking at 4.2 meV/c

Tuesday, 6/5 - OWL SL=Jean-Sebastien REAL

    Background and systematic studies at 4.2 MeV/c

Wednesday, 6/6 - DAY, SL=Joe GRAMES

    Test of the apparent cross-talk between magnet power supplies
    Optimize positron collection at 3.2 MeV/c


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