User name Anklin
Log entry time 10:46:06 on February 24,1998
Entry number 58
Followups:
- 59 02/24/98 10:53 Anklin additional plots
- 60 02/24/98 10:59 Anklin additional plots
- 98 03/24/98 10:22 Anklin BCM2/BCM1 hardware offsets
BCM data for the relevant runs are shown in the next few plots. The analys is based on the 16707 calibration.
Figure 1:The Ratio of BCM1 / BCM2 starts to be beam current dependent at about
run 17050. The same behaviuor can also be seen in 1/2 and 2/3. That means
more than one BCM drifted ! As a first assumption this could be 1 and 2,
since they are located in the same crate. That crate's power supply turned
bad and has been replaced later during the thanksgiving break. With the
intrinsic data (charge#####.txt) further studies can be done. Either the
offsets or the gains could have drifted!!!
At run 17131 two things have changed: first the beam current dropped
from roughly 100 microA to 40 microA and the unused frequency generator
has been removed from the faky crate.
After the thanksgiving break things look more constant. Beam current
was kept constant. The dip in the 1/2 ratio has already been explained in
hclog entry 2788. it is very likely due to a instability of BCM1.
Figure2: The expected (!) current dependence of the ratio 1/2 from calibration
run 16707. Due to different gain settings of 1 and 2 a nonlinearity
is expected at very low beam currents, where the one with the higher
gain starts to fall of the linear range of the amplifier.
But the expected deviation at 30 microA is about 0.05% !!!
The plots 1/3, 2/3 and beam current monitored with bcm2 are shown in the following
fpilog entries:
FIGURE 1
FIGURE 2
