GlueX Target Meeting, December 21, 2010
Contents
Location, Time
Tuesday, December 21, 2010
1:30 pm EST
JLab: CEBAF Center, Room F326
Agenda
- Review minutes from previous meeting: all
- Refrigerator plans: Chris, Tim
- Schedule review: all
- MOU Status: Mark
Communication
Conference Group, US: 800-377-8846, Canada: 888-276-7715, International: 302-709-8424
participant code: 77438230
ESNet: 8542553
EVO: direct meeting link, phone bridge ID: 269 1668
Slides: talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2010-12 on the JLab CUE. This directory is accessible from the web at https://halldweb.jlab.org/talks/2010-12/ .
Minutes
Present:
- JLab: Hovanes Egiyan, Mark Ito (chair), Chris Keith, Yi Qiang, Tim Whitlatch, Elliott Wolin
- UMass: Rory Miskimen
Refrigerator Capacity
Chris talked to the manufacturer of the pulse tube refrigerator we are considering and was told that the most common use of the unit was for helium liquefaction, so operation of a 4He target would not be a problem. It should provide 1.5 W at 4 K. At liquid hydrogen temperatures it should be able to provide 20 to 30 W.
Hovanes mentioned that for photon running in Hall B with hydrogen, the target uses about 5 W. A heater is used to regulate the temperature (and thus prevent the hydrogen from freezing). A few Watts needs to be provided, typically.
Chris also noted that in Halls A and C they typically run hydrogen at 19 K, at about 3 psi over atmospheric pressure, supercooled to avoid bubbles.
Helium-3 requires more power but is not in the plan at present.
Work Plan
Chris plans to start work on our target system this Spring. He and Tim have identified some of the major work areas:
- gas system
- refrigerator system
- heat transfer system
Right now he is swamped with polarized target work for Hall A.
Chris: contact physicist to be able to operate target without adult supervision
Controls
Hovanes brought up the issue of controls.
- Chris has starting looking at the flow diagrams for the Saclay target system in Hall B. He thinks things can probably be simpler.
- In Halls A and C, the dependence of externally controlled valves has been minimized; mechanical controls are used whenever possible. We should probably do the same for Hall D.
Schedule
Mark flashed the target costs and schedule that is in the current baseline. As part of the ETC change request Tim is updating this section (WBS 1.5.5.2) adding some new items and updating cost estimates and starting dates. For example, the purchase of a refrigerator is not in the current baseline. Right now both he and Chris do not feel we are in any sort of schedule trouble.
Next Meeting
We decided to meet again in 4 weeks. Mark will schedule a meeting.
