Present: Chris Allgower, Andy Bacher, Hermann Nann, Paul Pancella, Tom Rinckel, Sitaram Shastry
Meeting came to order at 3:10 pm.
SEPTUM MAGNET
Tom reported that both coils are finished, nearly. Water flow testing is underway, and temperature switches are still to be installed. The readout system for all 132 temp. switches is already available. Substation shutdown is scheduled for November 20/21 to cable in the big power supplies. With the current beam schedule, this means mapping can begin December 18. The vacuum chamber pieces which were machined outside are now coming back, so the vacuum chamber should be available and leak-tight in time to be assembled for mapping.
VARIOUS TOPICS
The vendor chosen to make circuit boards for the MWPCs has failed to deliver, causing a delay in their fabrication. We might have boards from a new vendor in a couple of weeks.
Stephenson reported (remotely) that many of the electronics modules we requested from Brookhaven will be available for us to borrow. We decided to let him follow up on this and find out if any FERAs could also be had.
In his last iteration, Chris managed to fix 3 lead glass detectors out of 12 attempted. This effort continues, as does the construction of delay boxes.
Chris said we now have lots of cable on spool ends which should be made into LEMO cables for general purpose. He was informed that was a job we could turn over to the operators to perform on slow shifts.
Thinking about the channel test, Chris asked for a figure on the expected time of flight between the first scintillator and the end detectors. Pancella volunteered to calculate it. He also suggested the reaction dd->pt as an alternate monitor. Consensus was that this cross section is probably not as well known as dd elastic.
LEAD GLASS
Pancella presented a lead glass configuration that exists within the boundary conditions that have been established, and appears to be as efficient as the stack which Pickar modelled in GEANT. There was much discussion and clarification for the group. Principle change is a reduction in the number of elements in the beam right stack, so that the total number of channels does not exceed 256. Total number of elements beam left will probably be 110 (mostly ANL bars with 10 or 20 IUCF in the center) and 144 beam right (all IUCF with 4 of the large blocks) so that no group of 16 is split across the beam.
LUMINOSITY MONITOR
Pancella included in his presentation some discussion of the luminosity monitor configuration that has grown out of previous meetings. He now envisions detecting dd elastic scattering at the target in a plane rotated 57 degrees from the horizontal (about the beam axis) low on beam left and high on beam right. A small scintillator telescope could be located outside the vacuum immediately downstream of the 6 degree chamber above and right of the beam pipe. This would be a deltaE-E arrangement (with some degrader) tuned to stop deuterons scattered at 5 degrees in the lab. Near the target nozzle inside the vacuum (beam left and below the target) would be a solid state PSD of roughly the same dimensions as used previously (1x5 cm) with the long axis along z. This detector could then see recoil deuterons in coincidence with the scintillator telescope, and be triggered independently of the main CE78 detectors. A coincidence would assure 2 charged particles from the target region, and the forward detectors should be able to separate d from p. The position of the recoil particle should give some information on the gas jet target profile along the beam. This configuration provides the minimum obstruction of the lead glass array, especially if a PSD can be obtained without a frame or heavy housing.
COMPUTER ACCOUNTS
Chris tried to look through some of the accounts mentioned last week that are due to be expunged. We decided to request that accounts belonging to Pavel and Adam Smith be kept active, and that whatever we want from any of the others should be transferred to other active accounts before next Monday.
The meeting adjourned at about 4:30 pm.