PrimEx Collaboration meeting May,5 2001

Valeri Koubarovski.: Presented proposal for adding 4 IHEP members to PrimEx Presented list of parts from Serpukhov detector that they are willing to contribute to PrimEx (includes 1000 lead-glass detectors with tubes and frame, 1600 channels of delay cable, ...

Ashot: Called for vote to include Valeri's group. The vote was to accept. Introduced Riad Sueliman (postdoc for Stan at MIT). He is willing to work on a PrimEx project (as yet unidentified).

Mark Ito: Status of Dipole Mapper is installed Power supply is being commissioned LCW (cooling water) should be done Monday. EH&S done P.S. High voltage cales being made Vacuum box windows being made schedule Survey 5/8 start mapping 5/9 mount PS frame 5/15 remove mapper 5/16 install PS detectors ?? Hall closes 6/1 Ashot expressed concerns about the schedule. A short discussion ensued. Ashot Gasparian says, "Be Alert!"

Phil Cole: PS targets going into Superharp ladder for G8 5E-4 and 1E-3

Dan Dale: Pair spectrometer status Dan gave an overview of the PS geometry. For G8 running, the PS will use a target mounted on the Superharp. Scintillators are polished at U. Kentucky and will be brought out on Wednesday Light guides are being polished at jlab and are nearing completion Have PMT's, magnetic shielding tubes, and voltage dividers for upstream tubes. There is a design and prototype for downstream voltage divider Fiber optic will be attached to each light guide or detector for later attachment to light monitoring system A total of 16 detectors will be installed before June. (PrimEx plan eventually calls for 32 total. Berhard had asked for total tagger coverage which means 64 total) Still need to soldier the voltage dividers for downstream tubes.

Phil Cole: Pair spectrometer Monte Carlo Code inherited from Dan Dale who got it from Ashot. Conclusions: 10 kGauss field 1.0E-3 radiation length target (650 Hz for CUA/g8 and 200 Hz for PrimEx counters) Positioning: CUA/g8 paddles: 7inches from beamline (2 paddles each side, 6 inches each) PrimEx counters: front: x=15cm z=254.4cm back: x=19cm z=301.6cm

Liping Gan: Pair Spectrometer electronics Liping overviewed the original plan for the Pair spectrometer electronics and the recent (significant changes)

Abdellah Amidouch: Dipole mapping status Mapper is in the Hall and mounted Software is nearly complete. (Motors turn etc..) 25 micrometers accuracy. (but survey accuracy is less and limit switch reproducability is unclear) 2 NMR's are installed in the vacuum box. Fields to map: 1.5T 1.6T 1.0T 1.4T 0.3T Liping expressed concerns about the state cycling procedure to ensure reproducability. Also, de-gaussing procedure needs to be established.

Sam Danagoulian:Light monitoring system laser, fibers, filter, ... etc. have all arrived. LED system is more stable than laser system (laser system will be auxillary for us) No dependance on angle or position of LED to better than 1% Summary: The LED system looks like it will work. A Discussion of how to attach the fiber optic cable to the light guide for the p.s. detectors developed.

Glenn Warren: Veto detectors Gen01 Paddles BC-408 160cm x 11cm x 1/4 inch Attached PMTs 2" Phillips 1262B (CERN housing) Used as a large volume charged veto They overlapped detectors by 1/2 cm Joint between scint. and light-guides are somewhat fragile (i.e. if positioned horizontally, the tubes must be supported.) Only bases and PMT's come with them. NO OTHER ELECTRONICS WILL BE SUPPLIED WITH THE PADDLES Ran them at ~100kHz Available: 1-2: July 2001 12: Jan. 2002 Rory asked if we could have 2 by August,2001. Answer: "probably".(Assuming gen01 does not need either of their 2 spares) Signal attenuation measured at greater than or equal to a factor of 3 There's a possibility we'll want to replace the PMT's

Rory Miskimen: Targets X-ray attenuation scanner built and used at UMass Uses Am241 source (60keV photon) Problems related to Compton Scattering require an additional correction factor. Sn120 targets ordered from Oak Ridge (Sn116 will not be leased (instead, we will buy Sn120) Target ladder has been built (except for the motors) Ladder cartridge design complete. Eric Clinton will begin work on Epics slow control software for target ladder this summer. Should be able to install in vacuum box this August.

Ashot Gasparian: Hycal Development Ashot showed a drawing of a proposed Hycal prototype that consisted of 60 PbWO4 crystals 84 Lead-glass detectors temperature control (similar to earlier PbWO4 prototype) A discussion broke out over specifics of how the detectors are layed out. Eventually, it was decided that the descussion was better suited for a weekly meeting.

Liping Gan: Cosmic ray studies Liping showed the results of her recent studies of various wrapping and optical coupling options for the PbWO4 crystals. While optical grease was better, she was able to achieve comparable coupling with a thin cookie.

Bitau Bitau showed results from his recent studies of the transmission properties of the lead-glass. measurements are consistent with prediction transmission is dominated by reflections (absorption is very small) Chinese crystals have slightly worse transmission than Russian one. Since the Chinese have better light production, this shouldn't be a problem.

Ashot Gasparian: Crystal Procurement The current form of the contract contains the following: We will purchase 100 crystals which satisfy the specifications used by CERN when buying crystals from Russia. We can decide to not buy any more crystals for any reason we decide after we buy the first 100. If we do decide to buy, then we will get the same price and the remaining crystals (1250 total) will be made to satisfy the same CERN criteria.

David Lawrence David gave a brief update on where we stand in Electronics procurement. CAEN HV protoype should come in June (production units in September Connectors ordered for HV cables, but cable not ordered yet. (will be soon) Electronics rack placement still an outstanding issue, though we're coming close to a final plan.