Hi chris,
I understand you missed most of your events in the forward region, for e-
corrisponding to proton paddles 9-14.
It can not be rad tail since that is continuous. However the front tofs
are only 15 cm wide. Assuming (for discussion sake) they really project
out 15 cm perpendicularly to the e-track (it could be less becuase of the
angle) than 7 % would be a 1 cm gap (7 mm for a 10 cm projection).
This number a bit high but maybe not completely unreasonable. We may be
less efficient when a track traverse part of the 1" thickness (which adds
to the definition of the gap..).
Or maybe a part of these events are random hits that somehow make it
through your cuts (z? coplanar ? "proton" adc ?)
-- tancredi
P.S.
Certainly 93 % is not a very good number for tof efficiency for e- !
I understand it is a worst case scenario number
________________________________________________________________________________
Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
On Tue, 2 Nov 2004, Chris Crawford wrote:
> being concerned about rates in some of the tof scalers, i decided to
> look at the tof efficiency in the recent 32deg and 45deg runs. i looked
> at events with good wc tracks in both the left and right sectors, and
> then counted the percentage of events missing either the left or right
> tof. so this gives information about the efficiency, but is is smeared,
> since the efficiency is not as a function of the missed tof, but instead
> the paddle number of the corresponding tof in the other sector. the
> missing tof events were unprescaled according to the trigger number.
> anyways, the conclusion is that 17 TOF's were at least 98% efficient,
> while the rest were at least 93% efficient. this does not take into
> account space inbetween the paddles, etc, but gives a general impression
> of the performance.
> --chris
>
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