This is a belated entry describing a new wall we added yesterday just before the end of the down. The existing lead and boron shielding around the Compton PMT was largely lateral, surrounding the tube. The view downstream into the hall was largely open (apart from a dipole magnet, which would be relatively transparent to low energy neutrons).
Megan and I added five 6"X6"X2" lead blocks in a wall of two blocks standing atop three blocks (which are standing atop three courses of brick on the table, to elevate the lead blocks to be centered on the PMT). A wall of four 20-mule-team Borax boxes was placed upstream, in the gap between the dipole and the leg supporting the electron-detector table.
A unistrut frame was built to prevent the top lead blocks from toppling onto the GSO detector in the event that someone/something knocks them over. The table motion is unaffected and the blocks showed no sign of motion when the table went through it's full range of motion.