Tagged Beam R&D Milestones

Tagger Design

• 12/6/2007 - The tagger specification and Statement of Work documents for the 100% tagger engineering design bid package have been completed and sent on to purchasing for review. The 12GeV Program Office has already approved the procurement.
• 1/8/2008 - Tim has produced a draft of the tagger interface drawings that he has made, as a final piece in the bid package. Discrepancies between different sources of information were pointed out in email exchanges, are being resolved.
• 3-4/2008 - The first major milestone in the monitoring process set up for this project is in the March-April 2008 time frame. This will be finalized during negotiations with the firm who wins the contract.

Interface with Accelerator

• 1/23/2008 - Richard will to update the document 646 to incorporate the two developments of the improved beam emittance parameters and halo simulation and send around a note to the beam working group. It will be discussed at the tagged beam group meeting on January 31.
• 2/28/2008 - Elke will organize a meeting with the relevant people from CASA, accelerator division, and GlueX to review the electron beam requirements, with a goal of agreeing on a specification for the Hall D electron beam properties.

Photon Beam Collimator and Shielding

• 2/28/2008 - The drawings of the beam line shielding plan (see tagger engineering drawings under "beam line shielding") are only sketches. Franz Klein will take these sources and turn them into 80% engineering drawings.
• 2/28/2008 - Review the overall photon beam line alignment plan in preparation for presenting it at the meeting with CASA and accelerator division regarding electron beam requirements.
• 3/27/2008 - Develop a conceptual plan for the translation and alignment stages of the primary and secondary collimators. The 75% drawings must include the design of the collimator support elements and indicate what degrees of freedom require remote control adjustment.

Tagger Hodoscopes

• 5/15/2008 - Franz completes 100% design drawings of the broadband tagging hodoscope in preparation for the 2008 Lehmann review. The drawings will include the support structure for the broadband counters and the table on which the microscope will be supported. A rail for transporting a mobile radioactive source along the entire length of the broadband array will be included in the design.
• Microscope - The following drawings exist as a part of the 35% engineering design for GlueX.
  1. FiberSipmCouplingChimney.dwg, .pdf, .tcw
  2. Scintillators_WaveguideSegments_2x5.dwg, .pdf, .tcw
  3. Support_Structure.dwg, .pdf, .tcw
  4. TaggerMicroscope_Assembled.dwg, .pdf, .tcw
  5. TaggerMicroscope_ExplodedEnd.dwg, .pdf, .tcw
  6. TaggerMicroscope_ExplodedIso.dwg, .pdf, .tcw
• 3/15/2008 - Richard will produce a list of criteria for a 75% design of the tagger microscope, based on discussions with the UConn Physics machine shop supervisor and examples of other detector subsystems provided by Tim.
• 5/31/2008 - UConn students will produce drawings for a 75% design of the tagger microscope. The 75% drawings will include the design of the supports and whether or not remote control adjustment to the alignment is required.

Pair Spectrometer

• We have a shared interest with Primex in this device. Elke has contacts within Primex whom she will approach with the proposal that the Primex pair spectrometer be incorporated into Hall D as an integral part of the photon beam instrumentation.
• Members of the Yerevan group have expressed interest in working on some aspect of the polarized photon beamline instrumentation. We propose that they be asked to come up with a specification for the pair spectrometer and associated hodoscope counters. This specification will form the basis for a search for an existing magnet that might meet our need for a pair spectrometer.
• Richard will make contact with the Yerevan group and suggest that they focus initially on the specifications of the pair spectrometer, and not worry too much right now about an engineering design for such a magnet.
• Progress towards arranging for a visit from the Yerevan group to Jefferson Lab is slow. Richard will make contact with YERPHI colleagues to help move along the process of applying for visas, buying tickets, etc.

Diamond Radiators

• Yang has started to analyze the data taken at CHESS last month. Two of the diamonds we studied have very narrow rocking curves on the order of 15 microradians, and a third has a width of 30 microns. All three of these are of sufficient quality for R&D on thinning and mounting.
• Mounting continues to stand out as a problem. Yang noticed that rocking curves are often wider when rocking around an axis along the mounting wires than along an orthogonal axis. This suggests that the wire supports are unstable along this direction. This can be studied optically using a visible laser.
• Our present experience with thin diamonds is limited to one example, which turned out to be a bad one. We want to produce several 20 micron diamonds and study them using a variety of mounting techniques. The three diamonds of reasonably good quality that were examined at CHESS in 11/2007 belong to Element Six. Yang will contact Element Six and find out if they are willing to sell them to us, and what the price will be.
• Assuming we can buy them for an affordable price, we need to investigate firms that will be able to thin them for us. Several possibilities came up during discussion
  1. Element Six may be willing to thin them, as they have before.
  2. Another US company Diamond Knives may be willing.
  3. The source group at BNL is building up the capability in-house to thin diamonds using ion bombardment.
  4. Glasgow University has ion beam facilities that might be used. If we learn that experiments at BNL are successful, we might try it ourselves.
• Yang will investigate options 1 and 2 above. Richard will follow up on his contact with the BNL source group. Both will report on progress at the next working group meeting.