first a bit of good news (while it holds): The rewound coils have reached
4.95 Tesla and seem to be good. As far as I understand, one more test
is planned to go to the full 5.1 Tesla design value.
Also, it looks more and more like we are going to have our next EG1 meeting
on Friday, February 6, at CEBAF Center (Room to be announced). We will
likely begin at 10:30 in the morning (to avoid the installation meeting)
and continue into the afternoon as needed. All system experts (target,
Moeller, beam line, ...) should give a status report, since the Readiness
Review will occur soon thereafter (no firm date yet). We may postpone
a formal presentation of DAQ issues, though, unless someone from the DAQ
group volunteers. Keep sending suggestions for issues and presentations.
The Moeller group at FIU has generated a detailed task list which I have
posted to our Web site (keyed off the general Task list). If you can
take over any of these tasks, please let me (or the appropriate contact
people) know.
Last week we had 2 target meetings to advance the design work and settle
a few remaining questions. The main items of general interest are the
final stick design and the design of the "banjo" windows.
The stick will contain 4 target cells, one NH3, one ND3, one C12 and
one empty (to park the beam for tuning etc.). The cells will probably
be made out of KLF (a hydrogen-less plastic material) and will have
Kapton entrance and exit windows (1-2 mils thick). NMR coils will be
designed around the OUTSIDE of these cells to minimize dilution of
the target material. Prototyping is critical, especially for ND3.
The Genova group will finalize the stick design along these lines until
the end of the month and send DXF drawing files to CEBAF. We will ultimately
need 2 sticks (plus one spare), and the first one needs to be at CEBAF
for the acceptance test (hopefully early in March).
The "banjo" (cryostat) windows will be designed by Derek Branford,
Mikell Seely and Dave Cashy. The most important input needed is the
minimum distance from the stick axis (i.e. the free space needed around
the target cells). The entrance window may be 20-25 mm Ti foil (1-2 mils)
and the exit window will have to be around 50 mm in diameter. A serious
consideration will be leaks, especially for superfluid He4. A test rig
will be used to prototype this.
Please send additional items I may have forgotten directly to this list.
Greetings -
--
- Sebastian