1. Calibration :
The pedestal program does not work correctly. There is alsoe "a certain
potential to missuse the program" (W.F.J.M.). The pedestals have to be
obtained as long as the whole electronics and the cables are connected. Also the
shapers have to be connected and powered on.
For the electronics will be the following priority list:
a. Pedestal
b. Time calibrator
c. Pulser test for linearity and relative gain calibration
2. Telescope spectra :
Because the gain of the preamplifiers was
too high only protons and alphas could be seen. The magnets in backward angle
(110 degrees) worked very nice for 100 Mev/N. The effect in forward angle was
much smaller. For 100 MeV/N an energy calibration with punchtrough particles
should be possible.
For the main experiment one should use large gain preamplifiers and reduce the
amplification of the shaper (which is now 20), because there was some noise on
the signals which was independent of the preamplifier amplification.
3. Rotation of the chamber for 1 GeV:
The delta electrons can be bent away with magnets around the target but is it
possible to see 2 particles in the hodocopes and how much does the threshold
increase? When the hodoscopes are in backward angles one does not see the
particles from midrapidity which punchthrough the CsJ and produce a lot of
Fast clear vetos. As an alternative one could trigger on the Si signals with
a high threshold und suppress the fast protons from midrapidity. According to
older data the target velocity will be less then 1 MeV. This means that the
threshold will be increased by approximately the same factor. The efficency
for slow protons and alphas from Lithium-5 can be very much decreased by
this effect but this has to be considered very carefully.
4.Hodo logic:
During the testrun there were some double triggers in the hodoscope logic boxes.
This can be fixed either by increasing the length of the hodoscope logic output
or by modifying the shapers. For the shapers the were some problems with an
unstable threshold. Roberto Bassini made a suggestion and will come at the 20th
of March and stay for one week.
Next meeting: 28.2.1995