Minutes of Hall A Group Meeting November 2, 2010
1)	Run Report: Aiden Kelleher (DVCS)
a)	For full report see: 
http://www.jlab.org/~kelleher/RC/RC_02nov10.pdf
b)	Gives details of the week’s work
i)	Most notably went from 2 to 3 micro Amps with 
reduced deadtime on Sunday (10/31)
c)	Beamtime:
i)	ABU: 103.9
ii)	BANU: 26.18
iii)	BNA: 20.98
d)	Today doing  production running at 3 micro Amps
e)	DAQ details: converting from running with FADC’s 
in non-buffered mode to buffered mode made a 
large improvement.
i)	Non-buffered: 2 micro Amps 20% deadtime
ii)	Buffered: 3 micro Amps 6% deadtime
f)	Møller:
i)	Magnet now at 80K which will save access time 
to refill, but will require two day shifts to 
re-cool.
ii)	Problem with the polarization sign (it didn’t 
change when it should have?)
g)	Shows missing mass squared spectrum. Peak is 
where expected
h)	Plans
i)	Re-survey of calorimeter Thursday (11/4)
ii)	Qweak target cool-down Thursday or Friday 
requires Hall A target warm-up/cool-down
iii)	Change kinematics in next few days, but stay 
at this energy
iv)	Perform large charge asymmetry runs to double 
check the sign of asymmetry.
2)	Jack Segal
a)	Expect to be ready to swap out the ethanol 
refrigerator on the VDC gas system on Thursday 
(11/4)
3)	Al Gavalya
a)	G2p work continues
b)	Møller cryo-distribution can is in drawing 
production
c)	Compton replacement of window with window and CG 
flanges will require a bit of work. Møller cryo 
has priority.
4)	Bert Manzlak
a)	Please obey posted speed limits, especially 
inside the accelerator site where there’s a lot 
of construction traffic.
b)	Bicyclists are informed that the west arc roadway 
is one-way and that applies to them as well. When 
riding a bicycle all rules re motor vehicles 
apply to you as well.
c)	COO, RSAD, and ESAD are in the counting house. 
Experimenters, please, read and sign them if you 
haven’t already
d)	Experimental staging building, ESB, #23
i)	Jack Segal is the safety warden
ii)	Now being filled
iii)	Contact Rolf Ent if you think you need or 
could use some space.
e)	ESH&Q has a contractor coming every two weeks to 
calibrate tools. The collection point isn’t yet 
determined. See Bert (manzlak@jlab.org) or Steve 
Smith (sjsmith@jlab.org) for more information
5)	Sasha Glamazdin
a)	Reports on the finalized systematic error for the 
Møller Polarimeter
i)	For 2005-2009 the total systematic error is 2%
ii)	Summaries are posted on the Møller webpage 
(http://www.jlab.org/~moller/index.html)
b)	Shows the Møller result for 27 October. Discusses 
the sign problem that Aiden mentioned.
6)	Bogdan Wojtsekhowski
a)	Reports on efforts to test/repair FPP chambers in 
the teslab
i)	So far only looked at one of four chambers
ii)	Major gas leaks identified and repaired
iii)	Several dozen wires are broken
7)	S. Zhang reports on investigation of power losses in 
the Compton cavity
a)	Focused on mirror damage
i)	Surface profile measurement shows no 
significant damage
ii)	Mirror coating loss is significant
(1)	All three mirrors have losses higher 
than the specs
iii)	Laser damage measurements
(1)	9 hours in vacuum with 140kW/cm2: no 
damage
(2)	8 hours in air with 250-400kW/cm2: no 
damage
b)	Conclusion:
i)	Laser damage ruled out
ii)	Coating reflectivity degradation likely 
induced by electron beam radiation
-JJL