[APEX] APEX meeting Monday, March 7 at 11:30am EST

[Jack Segal]

   I only have a few points to make that might be of interest. I can put
them down in this email. This is probably a good way to do it so Hall A
has something to work with.
   For high background rates, any electronics are at risk. Generally, when
things have died, we have tried to relocate the replacement or replace it
with something more simple and more radiation "tolerant". This sounds kind
of nice, but doesn't change the general areas of concern. There are all the
racks of electronics along the beamline. The electronics on the platforms
behind the dipoles. The cryogenics controls underneath the dipoles. The
spectrometer motion control under the platforms behind the dipoles.
   People might ask if there is anything we have particular concerns about.
Since the answer is "everything". We seem to have settled on a threshold for
concern of 10^13 n/cm^2 in terms of 1-MeV neutron equivalent in silicon. So,
if you start creeping up on this number it is best to look at the shielding.
   Sometimes we get bit by the overlooked pieces of equipment. The Left Shield
House Inert Gas Fire Suppression controls were a problem during PREX. If
something like that goes down the experiment has to stop. The bad part is
that any repair has to be done by "qualified" personnel and has to have some
review. That can be costly and take a lot of time. Plus the repair is no more
radiation tolerant than the original. If the spectrometer is parked with a
good view of the dump, the Shield House door controllers can die and no one
can get access to the inside of the Shield House. That can be a problem for
working on the DAQ. Odds and ends like these tend to be overlooked. When they
are identified as a problem they tend to be given a low priority, do not get
addressed, and cause problems later on, again.
   Kent Paschke's approach of trying to contain the source terms in as small
a volume as possible seems to be doing some good for PREXII. A couple of things
I had to point out to them. The wall between the beamline and the electronics
racks upstream of the pivot is made of cinder blocks, not concrete. I forget
the exact history of how it ended up like that. Also, the green shielding
blocks we use around the hall are scrap iron, not concrete.
   That really is about all I have, other than try to answer any questions.

On 3/4/2016 5:47 PM, Philip Schuster wrote:
> Dear APEX Collaborators,
>
> We will have our weekly meeting on Monday, March 7 at 11:30am eastern.
>
> *Agenda:*
> — News
> — Discussion about Run Plan (Bogdan)
> — Dry Run of Radiation Talk (Maduka)
> — TBA (Jack Segal)
> — AOB
>
> *Call-in info:*
> https://jlab.bluejeans.com OR phone number: 1 888 240 2560 <tel:1%20888%20240%202560>
> Meeting ID: 724003167
>
> Best regards,
> Rouven, Philip, Natalia, Bogdan
> for APEX
>
>
> _______________________________________________
> APEX mailing list
> APEX at jlab.org
> https://mailman.jlab.org/mailman/listinfo/apex
>

-- 
John(Jack) Segal
Halls A and C Spectrometer Support Manager
Thomas Jefferson National Accelerator Facility
12000 Jefferson Avenue
Suite 12
Newport News, VA 23606-4486
Phone: (757) 269-7242
Cell: (757) 320-9977