Cooler-CSB GROUP MEETING MINUTES

May 28, 2002 - (EJS)

Present: Chris Allgower, Andy Bacher, Hermann Nann, John Olmsted, Tom Rinckel, and Ed Stephenson

SMALL ITEMS:

• A reminder was issued to let Ed know if there are particular times or conflicts that should be included when the schedule for the next run is made. (Hermann reported that he will leave for Germany July 17.)
• There are three full bottles of deuterium available for our use.
• Alan Eads has checked and cleaned MWPC-1. He reports that there was evidence of sparking on the high voltages planes. He cleaned the chamber and says that it is ready for use again.
• The two bottles of HD gas are available, but will need a special regulator which isn't in hand. Bill Lozowski will look into this.
• Tom will create account "c78g" and back up previous account to tape.

CHECK LISTS

Before the meeting, Ed circulated a list consisting of four possible check lists of items that would need to be monitored during the production run on various time schedules. By the end of the discussion we had evolved to the following summary:

• Start of Each Run
  1. Go through and check that all scintillator voltages are on and OK.
  2. Check silicon for voltage and signal.
  3. Look at MWPC spectra to make sure all cards/latches are working.
  4. Look at summed delta-E2 and E for the loss of one signal.
  5. Look at Delta-E1 pedestal ratios for loss of signal.
  6. Are the interruptions on the event noisemaker?
  7. Is taping on to a valid event file? What is file name?
  8. Does traceback originate at target position?
  Log the following:
  1. Computer livetime.
  2. Between cycles, get event 5 (inside 5002) and event 6, left and right deuteron gates. Calculate ratios.
• At the End of Long Runs
  1. Repeat the list above.
  2. Record designated feature from each scintillator spectrum.
  3. Check cosmic data for Pb-glass peak shifts.
  4. Record the stored event file size.
• Upstairs Vacuum Log (repeated every 2 hours):
  1. Record ion gauges and thermocouples for target on and off.
  2. Record typical full current at the start of the flattop.
  3. Record beam lifetime.
  4. Record nozzle temperature, pushing pressure, flow.
  5. Record which flattop combos are on, and a what values.
  6. Record values for channel magnet currents.
  7. Record BPMs near target box.
  8. Record silicon voltage and leakage current.
  9. [Record Hall current/voltage readouts.]
• Downstairs Log (once a day or upon entry):
  1. Record H2, D2, and HD gas levels.
  2. Record channel vacuum.
  3. Record silicon chiller temperature.
  4. Record MWPC parameters:
     - Argon bottle pressure and isobutane weight.
     - Flow tube readouts.
     - Check bubblers, alcohol level, refrigerator temperature.
  5. Record cryo temperatures.
  6. Record ion gauges and thermocouples.
  7. Test suspicious cryos for pumping quality, note results.
  8. Record room temperature.

There may also be a run sheet to be filled out at the start of each data run. We can look at samples from the PINTEX group.

DATA ANALYSIS

John Olmsted reported on various replay results.

At the end of the run, the overlap of the X-position distributions for the left and right 44-degree detectors was not as good as when it was adjusted during the run. This raised the possibility that things had changed during data acquisition, so several items were tracked as a function of run number. The number of events that were counted as deuterons for both 44-degree detectors experienced a 10% jump relative to the event-5 rate when the beam was moved from T_WIDE combo setting 1000 to 2000 (the nominal best value). This jump was greatly reduced when somewhat larger deuteron windows were tried, indicating that it originates from some small change in the spectra. As a part of this, Ed calculated that moving the beam by 1 mm horizontally would cause the double differential solid angle to change by 10%. It is not known by how far the beam actually moved.

John also showed a replay for single Pb-glass hits that combined all of the d+d data from the last two runs. There is a weak indication of an alpha+pi0 peak. But John subsequently found that the time peak had shifted at the end of the last run in the corrected Pb-glass time spectrum, and most of the good Pb-glass events were begin missed. Including these produced a general smoother distribution with no pion peak.

In discussing the causes of the time shift, it was realized that a change to the phototube voltage for the channel scintillators could affect the readout time, as could phototube gain sag. After the meeting John generated some raw time spectra that showed shifts of dozens of channels. Since this has a direct impact on the missing mass reconstruction, it needs further investigation quickly in case there need to be changes to the run plan. Ed will help to investigate.