Real Photon Collaboration Engineering Meeting

4/30/02 Minutes

Attendees: 

W. Olson, S. St. Lorant, D. Walz, A. Angelov, P. Bosted, R. Arnold

Items Discussed: 
1. P. Bosted and L. Keller have been evaluating the LBL magnetic analysis of the E160 spectrometer magnet configuration.  P. Bosted is comparing the various wedge options for the spectrometer and finds the shorter wedge looks better for the 15 GEV runs.  Shielding the PMTs from the magnetic field is a design problem that needs further investigation, also.  More evaluation is needed before final decisions can be made.
2. The 3D3 aperture internals are pretty concrete.  The target system in the front half and graphite filling the downstream half.
3. The DC2 collimator was discussed and a decision made to replace it with a simpler design. It will have a fixed bore with the collimator itself being the vacuum chamber. This will provide a simpler more reliable system to install and align. R. Arnold, D. Waltz and P. Bosted will meet to discuss this possibility.
4. Alignment of the spectrometer magnets was discussed.  The alignment tolerance for the magnets is +/-1mm in Y and +/-2mm in X.  However, there is a complication with the beam pipe, which needs a tighter alignment. One thought was to align the magnet in Y and the copper in X.  Other questions were the allowable gap between the iron and copper plate, and between the copper plate and the beam pipe, and should 316L be used instead of copper between the iron wedges?  These questions and more will be answered as the design solidifies.
Decisions Reached
1.  Replace the E-158 3DC2 collimator with a new simpler design.
New Action Items
1.	R. Arnold, D. Walz, and P. Bosted will meet to establish the design requirements for a new 3DC2 collimator.
Ongoing Action Items
1. J. Weisend will work with D. Crabb and R. Principe to develop a detailed drawing showing the dilution refrigerator and the proposed superconducting magnet 
2. Number of cables required from the counting house to ESA. P. Stiles and A. Angelov will start tabulating these numbers based on the data acquisition memo and additional information from the collaboration.
3. P. Bosted will continue the physics simulations of the proposed change to the RPC design.
4. . 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.
5. Serious engineering of the shielding and earthquake supports associated with the LASS magnet must be started. 
6. T. Weber will investigate other E160 target materials to replace the Pb and Au for example Tantalum or Platinum
W. Olson