User name Eugene
Log entry time 17:01:32 on February 3,2002
Entry number 81656
keyword=DVCS tests with RCS calorimeter
Goal: measure the rates and backgrounds to DVCS using HRSL (for e-),
and the RCS LG calorimeter. The proton recoil is not detected.
E0 Q2 th_e- P_e- th_g* q E_g th_g
5.784 1.3 -14.6 3.500 20.2 2.55 2.23 20.0
The beam appeared for very short periods. We took about an 1h
run at about 4:00-5:00 3 Feb. At about 12:00 the beam came back
but VDC died and the test was terminated.
beam run length(min) thresh magnet veto target
1uA 2009 20 1500 off off 15cm LH
2010 25 1500 off on
10uA 2011 4 1500 on off
1uA 2012 15 1500 on off VDC dead
3uA 2013 15 1000 on off VDC dead
The trigger rates looks as follows:
beam threshold Tr1 Tr3 Tr5 Tr7
1uA 1000 9.0E3 1.5E3 2 1.5E3
10uA 1500 ? 1.1E4 30 1.5E4
Preliminary results are:
a) At 1uA the accidental coincidence make about 1/6 of the
b) The coincidence rate is about 20 times higher than the expected
DVCS rate, which is about 15 per 20 min run at 1uA.
c) No clear DVCS kinematical signature was visible in the missing
mass spectrum or energies correlarion plot. The statistics
was too low to hope to see anything.