Dear collaborators,
Jim Kelsey has worked out detailed CAD layouts of the possible final
positions for the neutron walls (existing NC and refurbished LADS).
Taking into account that four LADS bars out of 28 per sector have to be
excluded (due to lack of phototubes), there are now two approaches
optimized for two separate requirements.
The first approach optimizes the forward-angle acceptance, with two LADS
bars behind each other, resulting in 35cm thickness. The most forward angle is
thus 27.5 degrees. The two 15+20cm LADS walls overlap between 27.5
and 42.7 degrees. The price for this is the reachable most backward angle
for the NC, which is 80 degrees while providing still a small overlap with
the LADS walls around 43 degrees.
The second approach covers neutron angles with the NC up to 90 degrees.
Thereby, the LADS acceptance to forward angles shrinks a little and the
most forward angle which is covered is 28.3 degrees. The overlap
with NC is at 46 degrees. The two 15+20cm LADS walls overlap between 28.3
and 42 degrees. In a slightly modified version, the most forward angle
would be 29.6 degrees, and the two LADS walls overlap between 29.6 and
43.3 degrees.
The second approach is technically less difficult to handle for Jim, as
the first approach needs an additional support for the NC.
In the present layouts for the LADS positions, the lead glass detectors
can't be in at the same time.
As there might be different preferences from various experiments, it is
suggested to have a meeting tomorrow (June 3) at 11am in the conference
room) in order to discuss this and to come closer towards a decision
which makes everybody happy.
Regards,
Michael
--+-------------------------------------+--------------------------+ | Office: | Home: | |-------------------------------------|--------------------------| | Dr. Michael Kohl | Michael Kohl | | Laboratory for Nuclear Science | 5 Ibbetson Street | | MIT-Bates Linear Accelerator Center | Somerville, MA 02143 | | Middleton, MA 01949 | U.S.A. | | U.S.A. | | | - - - - - - - - - - - - | - - - - - - - - -| | Email: kohlm@mit.edu | K.Michael.Kohl@gmx.de | | Work: +1-617-253-9207 | Home: +1-617-629-3147 | | Fax: +1-617-253-9599 | Mobile: +1-978-580-4190 | | http://blast.lns.mit.edu | | +-------------------------------------+--------------------------+
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