BLAST Meeting for 22 January, 2003
Work on the LADS design continues. DH and JK will look at the available
space for the three different proposed positions.
Question of the shielding for the Cerenkov PMT's still an issue. PMT's
appear to be sensitive to few Gauss field and there is little or no space
inside the existing tubes to add mu-metal without extensive modification.
DH will talk to RA about present design and feasibility of changing it.
Plan to measure field in one of the tubes where extra shielding was added
to see how big a change this produced. KD will see if a bad tube is known
to exist in this Cerenkov box.
PK presented flasher and TOF status.
* researching commercial filters (price around $1k) but need to
modify supports and fittings
* yesterday they pulled the damaged TOF section and repaired it.
Should get reinstalled today.
o technicians helped so they are learning to do this
o PK making documentation
Flushing of the mylar windows with nitrogen on the wire chambers will
commence as soon as the technicians are free from work on TOF. Will also
reroute gas lines and tidy the cabling. Will change resistors on the
readout to get more signal (and noise) into the amplifier/discriminator.
Current resistors necessitate running with very low thresholds, near the
noise level of the electronics. The change will allow more reasonable
thresholds with a useable range. Changing resistors will take 2-3 days.
Also will modify cover plates slightly to avoid contact with the coils.
KD has ordered fibre optics for LADS. Existing fibre optics will be
removed and new fibres mounted at the centre of each LADS bar. PMT's are
being tested on their own with a Bismuth source. Scheme will work with
trigger and design for AND/OR/Adder. Work on base proceeding.
Compton polarimeter analysis as an MIT senior thesis available, BF giving
seminar at Michigan and will discuss spin flipper. Will prepare write-up
last Fall's running. Studying feedback for laser and electron to improve
performance.
ABS meeting today. Study dissociator also planned for today. Present
actuator can not move sextapole with field on. Sextapole slams in at 6000 A
and can not then be moved out. Very little motion of entire ABS seen with
field.
Cheers,
Douglas
26-415 M.I.T. Tel: +1 617 258 7199
77 Massachusetts Avenue Fax: +1 617 258 5440
Cambridge, MA 02139, USA E-mail: hasell@mit.edu
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