BLTWG Meeting 1/17/2008

• Time: 10:00 EST
• Place: EVO and ESNET
• Present: Yang Guangliang, Richard Jones, Franz Klein, Elke Aschenauer.

Agenda

1. Agree on a set of milestones to be achieved by our working group leading up to the CD3 review.
2. Summary of my discussions with YERPHI colleague Hrachya Hakopian regarding participation in Gluex and a visit to the USA.
3. Review engineering manpower needed within the group in order to achieve the CD3 designs in a timely fashion.
4. Yang's status report on analysis of CHESS data
5. Answer a query from Ken Finkelstein regarding our readiness to present results from our CHESS measurements at the CHESS user's meeting in June.
6. Discuss a suggestion from Ken Finkelstein regarding loan of a diamond to a CHESS colleague who is developing high-resolution crystal topography.
7. Discuss a strategy for buying some diamonds from Element Six and putting together some specifications for a thinning job.
8. Agree on a set of specifications for the tagger hodoscopes for Elton's spec document.
9. Develop a set of specifications for the beamline instrumentation, ditto.
10. Review my (upcoming) electron beam requirements document prior to our meeting with Jlab 12 GeV project staff around the end of the month.

Milestones

I have taken the notes from our meeting last December and condensed them down into a list of milestones. Dates beside each item indicate when the task is to be completed. The milestones page is now linked from the main Photon Beam page on this wiki.

YERPHI update

H.H. has replied that he has agreement from his supervisor A.S. for a visit from both of them during the first half of March. Elke thinks it is already too late to arrange for a visit at that time. She suggests a visit timed to coincide with the next GlueX collaboration meeting May 8-10. I agreed to contact A.S. with this suggestion and ask him to request from Elke an invitation to attend this meeting in May. He should state what the duration of the visit should be and what his goals are for the visit. There will be some exchange on what the goals should be and then Elke will look into what sources of funding are available to enable them to come.

CHESS measurements

A couple of questions from K. Finkelstein:

Hi Richard,
I wondered what's new with data taken during the last visit to CHESS, and if there has been enough accomplished to consider having you speak about it at our CHESS user meeting June 10-11, 2008. Please let me know what's happening and if you might be able to participate.
Thank you and Best Regards for a healthy New Year,

Ken

The data from the 11/2007 measurements are still be analyzed by Yang. The monochromator worked very well, so we now have rocking curves with widths close to the intrinsic diamond widths. Several of the diamonds we looked at are of sufficient quality to use as a GlueX radiator, and some are not. Unfortunately, the CCD camera was not in optimum focus during the 11/2007 measurements, and this will affect our ability to use these data as a defect diagnostic. However they do have enough resolution to decide if the diamond is of radiator quality or not, and to distinguish between different classes of defects. RJ will confirm with KF that we plan to present these results at the User's Meeting. Yang will present them earlier to our working group and get feedback, then write a document. We will discuss whether there is a NIM article in these data after that document has been received.

Just this week, I received a second question

Richard,
My colleague Alexander Kazimirov ( ayk7@cornell.edu ) has been developing a method that can produce depth sensitive topographic information. The first publication is attached. He thought it would be interesting to examine one of your thin diamonds as part of a study he will be doing at ESRF in a few weeks.
Would you be interested in lending him a sample? Because the work involves method exploration and development, the sample could be broken or otherwise not too valuable for your needs, but it still should be a good crystal. The thickness could be anywhere from, say 10 to 50 or even 100 microns.
Please let me know at your earliest convenience
Thanks, Ken

RJ will write back and ask for more details. Questions to ask are:

1. What is the probability of breaking it? What are the plans for mounting it, etc.?
2. What minimum size is required?
3. Are there any other requirements? planarity? well-known rocking curves already measured? if so, which planes?

Diamond procurement

The diamonds that we examined during the November, 2007 CHESS test run still belong to Element Six. I proposed that Hall D purchase a set (perhaps 3) of the good-quality diamonds we tested that are of sufficient area to be used as radiators so that we can do R&D on them. Yang says that we do not have to buy them in order to do R&D with them. Elke would like to a see some kind of statement in writing to this effect, stating that certain ones of the Element Six inventory held by Glasgow can be devoted to R&D for the purposes of Hall D, and especially stating what our liability is for diamonds that are modified during R&D, so they cannot be returned in their original state to Element Six.

Specifications

We are missing specifications for the following items related to the tagged beam.

• High level specifications
  1. The photon beam - Richard
  2. The electron beam - Richard
• Low-level specifications
  1. The tagger fixed hodoscope - Franz
  2. The tagger microscope - Richard
  3. The pair spectrometer magnet - Franz
  4. The pair spectrometer hodoscope - Franz
  5. The active collimator - Richard
  6. The diamond radiators - Yang
  7. The goniometer - Franz
  8. The total absorption counter - Franz
  9. The primary and secondary collimator - Richard
  10. The tagger spectrometer - Franz

Electron beam properties document

Richard will finish his revisions to the electron beam requirements document and push a copy to members of this working group by mid-week next week. Each of us will read through this document and prepare to discuss it at the next tagged beam group biweekly meeting on 1/31/2008. Elke reminded us of the feedback bandwidth issue for the photon beam position control that came up during the October collaboration meeting following Jay's presentation of the Hall D electron beam line design.