Dear all,
First, I have to say that my claim about huge drop of the rate at
the unpol run with increased
target density was wrong. As it turned out, I used wrong run numbers.
Now I'd like to present a clarified picture. eD elastic events are
used for retes.
1. Target density dependence in unpol runs.
a) normal density (Pbuf=2 torr) R=793+-6 events/kC
b) Pbuf = 1 torr R=424+-6
(expected - 397)
c) Pbuf = 3 torr R=1160+-12
(expected -1190)
One may note, that with reduced target thickness, rate is a bit
higher than expected, and at
high density rates are smaller than expected. Not by much, but ourside
error bars. I believe,
Nick observed similar picture in inclusives.
2) Current dependence in ABS runs, the target is at the same state
(age?) for both runs.
a) normal conditions (Imax~230 mA) R=674+-7
b) Imax=100mA R=904+-9
Here the effect is much more dramatic. At low current rates a MUCH
higher.
The only reasonable explanation I can come up witth is that wire
chamberrs efficiency (or, rather,
efficiency of reconstruction) depends on the wire chambers rate, and
that during our "normal" conditions
this efficiency is less than 75%. With low current, the chambers rate
drops very drastically, and changes
in target thickness have much smaller effect.
Genya
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