S117 meeting, 27.6.95
DAQ
Til end of the week pass 1 should be finished and Volker has installed the right
pedestals.
Mechanics
The alignment mount for angular measurements in the chamber will be finished
Wednesday.
Trigger documentation
Burkhard has checked the trigger (about 60%), the rest remains to be done.
Calibration
- The punch trough is quite tough to be determined analytically since the high
energy part which should determine the crossing point is not well visible.
Michael will have another try.
-
Burkhard checked the alpha-calibration one run with and one run without without
pulser. Without pulser the peak is shifted 10 channels higher out of 2000
channels (0.5%). Its a significant shift since the uncertainty of the mean is
below one channel.
-
A discussion came up if the research pulser has an offset. Hints for that
are:
-
For the silicon array the spacing of the alpha peaks give an pedestal of about
-1000 channels with large uncertainty (alpha peak in 20000, spacing about
2000), the pulser peaks give pedestals of about +100
channels. However, a possible explaination would be that the alpha emitters are
implanted in a matrix (a depht of 1/20 mu would be sufficient to get the rigt
energy loss)
-
Xis telescopes give pedestal information via the punch troughs and the pulser
peaks. Pulser peaks give always larger offset than punch troughs.
PID
Mahi introduced the Steckmeyer formula to improve the fits for the telescopes.
It fits now the low energy region quite well and works also for the
hodoscopes.
He introduced a peak finder according to the Indra procedure. He uses socalled
primary informations (slopes and spacing of z-branches) and determines the peak
positions. Even he didn't smooth anything, he got decent results and the whole
procedure seem to be promising.
The fits to the data points have to be improved yet for the p,d,t,a.
June 26th, 1995 Carsten Schwarz,