Minutes of Hall A Group Meeting May 25, 2010
1)	Run Report: Juliette Mammei
a)	For full details see 
http://www.jlab.org/~crowder/PREx_RC/PREx_rc_repo
rt.pdf
b)	Highlights:
i)	960 Hz raster synch reduces detector noise 
(Cates and crew)
ii)	Compton Background Rates high after Wien flip
iii)	Short Q2 measurement
iv)	Target vacuum problem Wednesday night
v)	Damage to PbD#2 with smaller raster (use 6x4mm2 
with 200µm spot)
c)	ABU 19 hours
d)	BANU 129 hours (124 hours from target vacuum)
e)	BNA 20 hours
f)	Total accumulated charge 31 C
i)	This week: 2 C
g)	Replacing o-ring with better one (better thermal 
properties)
h)	The Future:
i)	Ongoing maintenance work on LHRS magnets
ii)	Remote control of heaters/fan
iii)	Take production data!
iv)	Compton rates -address during beam studies
v)	Have extension to June 22. Shift workers 
needed!
2)	Installation: (Ed Folts)
a)	We are pumping down (no large leaks detected)
b)	Closing the Hall will depend on how the leak 
checking goes
i)	Minimum need two shifts to pump down
ii)	No beam before noon tomorrow (5/26)
3)	Al Gavalya
a)	Susan is working on g2p W inserts (need input 
from Alexandre)
b)	Whit (with Joyce) working on SRC detector lifting 
frame details
i)	Also working on Dewar boil off
c)	Joyce is working on frames
d)	Chris is learning the CAD system
e)	Al is working on DVCS and all the above
4)	Bert Manzlak
a)	Next Tuesday (6/1) is the beginning of hurricane 
season (June 1- Nov 30)
i)	Hall C is the point of contact for storm 
related issues
ii)	Each area has a checklist
iii)	There's information on the EH&S website about 
severe weather
iv)	Users' Group has a plan to get people off the 
peninsula in the event of a hurricane
b)	Work request is in to remove the poison ivy from 
the bushes at the entrance to the counting house
5)	Alexandre Camsonne on GEM status
a)	For full report see 
http://www.jlab.org/~camsonne/gem/presentation/
b)	Last runs with 4 chambers with improved grounding
c)	Shows plots:
i)	correlation with VDC plots
ii)	Efficiency vs. cuts
d)	EEL source tests on bottom INFN chamber
e)	More plots:
i)	Amplitude spectrum on cluster sum
ii)	Amplitude from Gaussian fit and integral
iii)	Gain Curve
f)	Gives future plans
g)	Conclusion:
i)	Signal improved with grounding and HV operating 
point study
ii)	HV a bit low for the first 3 chambers
iii)	One direction works better than the other one
iv)	 Software  in good shape for detector check 
and working on tracking
v)	Still work in progress - residual from VDC 
about 3 mm
vi)	Optimization of the chamber HV
-JJL

Minutes of Hall A Group Meeting May 25, 2010