Hello,
a full report (plots) on the beam tuning activity will be presented later.
Salient fact is that with this configuration we are very close to an "ideal"
beam position, meaning we are at local minima in the H,V displacements.
BQM rates track L,R single arm rates well. Improvement in BQM rate was
modest (20, 30 %) we had 50,30,15,20 Hz/mA at 95 mA, after the slits were
put in for a lifetime of 20 mins. See logbbok. The septum is still the
major player (50 %). Hopefully bqm rate will stay stable.
Preliminary analysis of empty targets shows that:
_ rate is high! : in the H-elastic cut we have ca 0.6 ev/C (empty)
vs 20 ev/C (0.1 SCCM gas, deltap= 4e-7). Note that this gas density is
at least factor 3 higher than ABS.
_ In the 1st attach the theta_e distribution of gas data scaled x1/3 (black)
vs empty tgt data (red). Data is also normalized according to charge.
_ In 2nd attachment the theta_L vs theta_R distribution of events from gas
and empty targets (in the elastic cut). clearly our "empty" rate comes
from hydrogen elastic. Can also be seen form coplanarity distribution
(sorry for not showing that). So that's where our icing went....
- Will need to at leat warm target, but not clear how to bring it above 0 C !
-- ________________________________________________________________________________ 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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