Minutes of Hall A Group Meeting May 11, 2010
1)	PREX Run Report: Seamus Riordan
a)	For full details see: 
http://www.jlab.org/~riordan/20100511_riordan_rcu
pdate.pdf
b)	Pb/D targets become more noisy as they take 
current
i)	Solution is in hand
ii)	Gordon Cates is working with raster experts 
today to make the solution permanent
c)	Compton cavity/chicane vacuum work (3.0 kW lock)
d)	Pockels cell driving electronics improved to 
reduce ringing after transition.
e)	Present hardware issues:
i)	Left dipole controls
ii)	Target vacuum >1e-4
iii)	NMR on right dipole not working
f)	Time summary:
i)	ABU: 71.5
ii)	BANU: 58.8
iii)	BNA: 37.7
iv)	Now have 25.3 C (out of 130)
v)	Collected 5.8 C last week
g)	Plans:
i)	Repair target vacuum and left dipole
ii)	Waiting to hear word on an extension
iii)	Production
2)	Installation: (Ed Folts)
a)	Lost fire suppression in the left arm
b)	Lost dump air compressor
c)	Target vacuum although improved is not yet where 
he’s comfortable
d)	Working on right dipole NMR
e)	Not optimistic about locking up tonight
f)	Question: do we need to have a target operator in 
the counting house tonight? Short answer, yes.
3)	Al Gavalya
a)	Robin is working on SBS magnet simulation. 
Expects to have a full map by June 1.
b)	Joyce is working on:
i)	Beamline shielding for the DVCS calorimeter 
(finishing)
ii)	DVCS detector mount (this week)
c)	Tungsten for shielding should be in by 19 May
d)	Whit working on cryo line for Møller warm return
e)	Machining and welding done for the downstream 
extension of the DVCS scattering chamber. There 
are some alignment questions. Ed will have a look 
at it.
f)	Almost finished with the light tight box for the 
DVCS calorimeter
g)	New designer will start work on Monday (5/17). 
Also, Susan will be back.
4)	Bert Manzlak
a)	Reminds us that undergraduates must be escorted 
during their 1st 3 months when working in the 
Hall. “Escorted” means you must stay with them.
b)	New guidelines are being drafted re injuries and 
illnesses. As last week, go to medical services 
if you’re sick or injured on the job.
5)	General Announcements: (Kees de Jager)
a)	PREX will be extended to June 15
i)	10 days transition the 4-5 days APEX running
b)	Summer down will be shifted by 3 weeks
c)	Impact on the rest of the schedule to be 
discussed in the coming weeks.
6)	Sirish Nanda
a)	Re Compton mirrors, talking with FEL people about 
mirrors. They are equipped to test for damage.
7)	Ole Hansen 
a)	Working on the same software projects
b)	Italian group has finished digitization of SBS 
simulations. Now has results to feed into his 
code.
8)	Alexandre Camsonne
a)	Working on DVCS DAQ
b)	INFN GEM chamber had problems. It’s been removed
9)	Bogdan Wojtsekhowski
a)	APEX detector preparation is completed
b)	Restoring VDC#4
i)	Mechanical aspects done
ii)	Stringing has started
c)	Albert has started design of the frame for S1m
d)	SBS: there’s a newsletter. Check it out! 
(https://hallaweb.jlab.org/wiki/index.php/Newslet
ters)
e)	Deadline for next PAC submissions is July 1. Has 
some proposals in preparation.
10)	Al Gavalya asks whether or not g2p will need to 
split the septum?
a)	J-P says that will depend on the radiation 
calculations. He expects results from Pavel in 
mid-May.
11)	Jixie Zhang
a)	2 more Møller measurements last week
b)	Møller problems:
i)	Magnet alignment not understood
ii)	Discrepancies with simulations
iii)	2.5% systematic difference between old and 
new analyses.
iv)	1% differences between target foils
-JJL