HORIZONTALS:
===========
There was an astonishing similarity to the led settings decided now
by step one with the ones back in Feb 96. The difference, if any ,
of one led step ie 0.01V, or rarely of 0.02V (on 1.11V)
For the two runs taken with the same "exact" led settings
one in Feb (12812) and one now(90665), she did notice a slight
shift towards smaller number of li counts in SM5:
ie it looks as if the same setting that would create 30-35 li
counts now it will create 25-30 licounts in the waveforms.
VERTICALS:
==========
There was a big difference between the led settings determined by the
first step run during last week(90765) and the ones back in February 96
(settings of 1.56V in Feb 96 went to 1.75V Jul 97). However, when she
analysed the second step run of last week , she found out that we were
on the "high" licount side and the efficiency is always 100%,
i.e. the new LED settings have missed the area of the efficiency step.
The analysis of the first run that decides the LED settings(90675)
looks OK and there is no clue to what might have made the verticals decide
wrong settings. A repeat of that calibration is planned but still pending
due to other priority issues during the following wednesday.
Comparing the run in February(12812) with that taken with the "same"
led settings on wednesday (90665) she notices the same shift towards
lower licounts for the same led setting, thus she misses the step
of the efficiency in quite a few tanks because the settings
are on the low efficiency side. It seems ,though, that the threshold
does not move (at least downwards) thus it is more probable
that it is a lower light response of the led to the same voltage setting.
Lower noise situation of the PMT fanouts might also account for that.
In addition, Sophia tried to address the issue of "hot" or "cold"
tohm tanks by performing calibrations for those tanks in SM3, SM4, SM5,
and SM6. A scheduled black out made this calibration to be in a hurry, thus
the LED parameters for those tanks were taken from the data back in Feb 96
hoping to catch the "efficiency step" area. Unfortunately most of the
44 tanks that were calibrated did not catch the efficiency step , something
that verifies once more the need of a "first step " run and better
calibration equipment. From the 65 tank-ends that were calibrated
31 didn't have adequate calibrations (the step of the efficiency was not
caught) 28 look ok, and 5 have clear problems. More calibrations are
scheduled for this week.
==========================
Stefano Stalio had helped with several of the ongoing projects reported
earlier during the first week of my shift and then took a much deserved
vacation for the second week of my shift.
=========================
Bob Webb spent his two weeks on shift helping the troops on the front line
carry out calibrations and various detector repairs( HV cards, WFD
triggering for lamosska and laser calibration on MV#2) reported in several
of the preceeding items in this report and nursing a terrible head cold
that set in shortly after his shift began.
respectfully submitted by your humble shift worker,
Bob Webb