[BLAST_SHIFTS] plan

From: Tancredi Botto (tancredi@mitlns.mit.edu)
Date: Tue Sep 16 2003 - 12:39:10 EDT


Continue measuraments at full reverse field. We should measure both
hydrogen and deuterium. CCR is tuning the beam: we may hope for a
BQM rate of < 200 after the slits are in (bqm-top), with an empty
target lifetime > 15 mins. Right now bqm-u is at 250 Hz/mA and
lifetime is > 30 mins (slits are out).

Attached the results of careful montecarlo simulations from march,
when the discussion about the run plan was initiated (at that time
priority #1 was to prove the wch could operate as in the golden runs).
Clearly our commissioning experiment could profit greatly from a
measurament at reverse field so the plan is to measure both ep and ed
channels and also study the chambers for potential charge up problems.

At 0.1 sccm (warm target) we should expect ca 12 events/C/sector. So at
least initially we need at least 400 C, which should correspond to about
3-4 hours or 5-6 runs. The easy was to check these numbers is

root count_charge.C run##'s (after charge.C)

whereas you can easily do

root flr.C run##'s
  root> flr->Draw("twl",Helastic_L)

After hydrogen we should continue with D2 measuraments for which the
xsection is ca 1/100 times less, as well as empty target measuraments.

I'll leave for now but am reachable by phone.
-- t
________________________________________________________________________________
Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
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