Real Photon Collaboration Engineering & Photon Beam Meeting

9/03/02 Minutes

Attendees: 

P Bosted, L Keller, W Olson, S Rock, S St Lorant, T Sanchez, 
D Walz, T Weber, J Weisend

Items Discussed: 
1. T Weber got a $13,000 price for 3m3 (40 sheets) of poly.  
Decision was made to use poly as the absorber in front of the 
front and middle spectrometer detectors.
2. Spectrometer target materials were discussed.  Tantalum 
would be a good substitute for gold.  T Weber pointed out that 
there are extra target mounting positions for alternate materials.
3. L Keller is working on the LASS/wedge arrangement and forces 
to see if the wedge and copper components position can be moved 
to minimize axial forces on them.  Concern was expressed over 
what would happen if there was a sudden loss of current.  
S St Lorant will calculate the current decay time constant.  
If it turns out that eddy currents in the copper are a problem, 
the copper can be made in smaller pieces and insulated from each 
other.  LBL is a possible resource for additional analysis to 
resolve these issues.  
4. Which magnet to use for the Compton polarimeter was 
discussed, and whether to use a septum, and helium boxes 
instead of vacuum chamber(s).  A septum in B203 was 
considered best.  Peter, Saint, and Bill will discuss 
these issues further after the meeting.
5. The SEQ was saved from salvage and now resides in ESA.  
Mike Racine will insure its safety.
6. T Thurston should have the CDR report finished by the end 
of the week.
Decisions Reached
1. Poly will be used as the absorber in front of the front and 
middle spectrometer detectors.
New Action Items
1. T Weber to investigate using water tanks versus poly sheets 
as absorbers in front of the spectrometer front and middle 
detectors.  This is tied to action item 2 below. (Complete) 
Ongoing Action Items
1. T. Weber will get prices for cast copper and tin.
2. P. Bosted to determine material to be in front of the 
middle spectrometer detector panel. (Complete)
3. J. Weisend will work with D. Crabb and R. Principe to 
develop a detailed drawing showing the dilution refrigerator 
and the proposed superconducting magnet. 
4. P Bosted will continue the physics simulations of the 
proposed change to the RPC design. (In progress)
5. The interaction of the LASS magnet and all its iron 
with the E161/ E159 7-T target magnet needs to be 
carefully modeled using a 3-D field simulation. (Complete)
6. Shielding and earthquake supports associated with 
the LASS magnet must be evaluated and designed.  
This action item was re-written and M Olson is working 
on it. (In progress)
7. T. Weber will investigate other E160 target materials 
to replace the Pb and Au for example Tantalum or Platinum. 
(Complete)
8. L Keller will identify all forces on the magnet system, 
and confirm the magnet configuration.  Adding whether 
re-positioning the wedge can zero the force on the 
wedge. (In progress)
W. Olson