[BTeam] more possible checks

[Jay Benesch]

At the 0745 meeting Hall B RC said they had calculated some tracks which started 4m upstream of target.  One vacuum valve in the vicinity was cycled remotely and didn't change background.  There is another valve which can only be cycled in the hall around that location.  They have requested a radiation survey to see if that valve is warm. 

________________________________________
From: BTeam <bteam-bounces at jlab.org> on behalf of Yves Roblin <roblin at jlab.org>
Sent: Friday, August 28, 2020 7:56 AM
To: bteam at jlab.org
Subject: [BTeam] more possible checks

Assuming the problem is not localized within Hall B, we can also check the bleedthru from other halls.
suggestion from Joe Grames:

If you close all slits and only run the Hall B beam at 250 MHz is the "cleanest" setup, to the extent B is not bleeding into B' and scraping into the Hall - I guess it should really be close to zero and the base line.   Next, open up only the A slit, to check for B into A, and then open up only the C slit, to check for B through C slit.    If no halo yet, then B laser is excluded from causing themselves grief.   After this, you could repeat with only each of the other beams, to identify the source of the electrons causing halo.

He estimates this is a 20 minute thing and he is willing to assist the crew do this in case they need to.