BLTWG Meeting 12/6/2007
From GlueXWiki
- Time: 10:00 EST
- Place: VRVS and ESNET
- Present: Aschenauer, Jones, Klein, Whitlatch, Yang
The agenda for this meeting was to review the status of all of the major systems under the oversight of the GlueX Tagger/Beamline working group, with the purpose of setting short-term goals and target dates for accomplishing things that must be completed in preparation for the 2008 Lehmann Review.
Contents
Tagger Design
- 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.
- Tim is working on 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.
- Elke will post the final revisions of the Tagger Specification and Statement of Work documents at the usual place on the wiki.
- 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
- Richard has written a document ``GlueX Requirements for 12 GeV Electron Beam Properties'' (gluex-doc-646). This document summarizes the GlueX physics requirements for the 9 GeV photon beam, and derives from these the requirements for the 12 GeV electron beam. The final section shows how these requirements can be phased in gradually within the context of the GlueX commissioning plan.
- Discussion of these requirements with the CASA group raised major concerns with two major points: emittance and halo. The former describes the r.m.s. size of the central intensity peak of the beam, while the halo describes the intensity at larger radius where it exceeds the gaussian fit. The concern over emittance subsided in early 2007 when the nominal beam emittance figures went down by a factor ~2 after a computational error was found. The halo concern remains.
- In Spring 2007 the CASA group produced an improved halo model based on a ray-tracing simulation through the accelerator. The GlueX tagger backgrounds have been resimulated using this halo model. The results allow the GlueX halo specification to be relaxed by one order of magnitude, while still adhering to the basic criterion of less than 1% background in the tagging counters.
- Richard needs to update the document to incorporate the two developments described above. End of January, 2008 is the target date for an updated version of gluex-doc-646.
- 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. A target date of the end of February is set for this meeting.
Photon Beam Collimator and Shielding
- Richard has produced the following documents which are a part of Tim's 35% design drawing library from the 2007 Lehmann Review.
- Detailed drawings of the active collimator
- Layout drawings of the complete collimator cave and contents.
- Collimator cave floor loading plan.
- The drawings of the beam line shielding plan (#2 above) are only sketches. Franz Klein will take these sources and turn them into 80% engineering drawings. A target date of end February 2008 is set for this task.
Tagger Hodoscopes
- Broadband array - Franz plans to do 100% design drawings of the broadband tagging hodoscope prior to 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.
