Minutes of 2 April 02 Dragon meeting

Present: DH,MC,DO,AC,JR,DG,SB,AO(recorder)

1) Prerun check list (DH):
-Earliest chance of Beam Sun night.
-DAQ tests to be done with pulser.
-One BGO has poor resolution (10%). It can't easily be replaced with
a spare, and it has a low count rate, so it will be left in place.
-Power supply for SX4 is working again.
-A pulser will be installed in the elastics channel for an additional
monitor of dead time.
-With the MCP in position another cup than FCF will have to be used
to protect the strip detector and MCP foil. There was discussion of
looking at protection via EPICS by inserting a blocking device
based on a strip detector scaler rate.
-The fence is complete, but the safety ASU will not be complete, so the 
procedure will be to give the master key to the operators in order to get beam.
-The lead shielding may not be installed for this run.
-Beta monitor should be installed and working for a redundant relative 
normalization.
2)Gas target study(DO,DH):
- Limit to our max target pressure comes from RB2B, which has a backing
pressure spec of 60 torr. With this we can get higher cell pressures by
opening a bypass valve.
With the bypass open a gas cell pressure of 10 torr has been achieved.
The pressure upstream to HEBT is still acceptable, but the downstream
pressure to dragon rises to 1e4. This may be a sign that we are
going over the knee of the turbo compression curve (see figure).
The power to the turbos goes from 180W to 280 W. 
This may lead to more leaky beam and a higher fraction
of gas outside the cell. 
-A run at high pressure may be useful in the initial search for the 
Na21 330 KeV resonance.

3) Update on Na21 822 analysis(DH):
-Final low intensity runs have problems with the elastics.
-Run 4800 has an unexplained discrepancy between FC4 and FCCH, suggesting
a bad tune.
-The elastic yield shape normalized to FC4 ignoring run 4799 looks very
much like the TUDA data. Run 4799 elastics have x5 lower value.
-Fitting everything but with FC4 (or elastics) normalization gives
width of 7 KeV (or 17 KeV) for a 15cm target length. The chisquares are
poor in both cases (see figures).
-A remeasurement of this level should include runs at E= 810, 825, 845,
860, 880 KeV/u. This program could be varied depending on on-line results.
These new runs would include important coincidence data.
It was also argued that our tuning procedure has been refined and it
would be best to do a full remeasurement and not rely on the old data. 
-The priority of this measurement was hotly debated. On the one hand there
is the desireability of commissioning the instrument on a strong RB resonance,
and resolving the discrepancy with TUDA. On the other hand, this is a
broad resonance and is not well known, so it is not an easy case for
commissioning. The consensus was that we should not devote more than
2 -3 days to this effort. 

4)Na21 212 analysis(SB):
Because the data at 210 KeV has significant losses in the elastics as
the peak is cut by the discriminator setting, it was decided to
retake this point.

5)Facility Upgrade(DH):
DH asked for input for facility upgrades to be requested for next year.
Items are new power supplies, FC1, Hall probes, FCCH catcher.