DRAGON minutes 11/5/04

ION CHAMBER TESTS.

    The purpose of these tests were to test the response of the Ion Chamber. It was intended 
to use a resonance in 21Ne(p,g) previously measured by DRAGON in order to detect coincident 
recoils with the IC-MCP setup. Here is what happened:

CR left alpha source holder in the beam - necessitating venting of the mass slit box. This 
resulted in the MCP foil rupturing.

Beam delivered at 2 a.m on the Friday owl shift. No coincidences were observed in the data. 
It was discovered eventually that 20Ne had been delivered to us instead of 21Ne. When the 
correct beam was delivered, there was an EPICS crash and the IC 55 ug/cm**2 window burst. 
The 130 ug/cm**2 window was put in.  

Before beam could be delivered there were problems with MIDAS - there was no ONLN in PAW++. 
Problems with noise were then discovered with the IC and elastic monitors.

Several pressures in the IC were used to move the recoils & beam into separate anodes to 
facilitate separation. It was found that by sacrificing 10% of the recoils, could eliminate 
80% of leaky beam this way.

With the final slits wide open, the leaky beam rate was about 10 times the recoil rate.

A charge state distribution was investigated, and showed that the poulation of the 4+ state 
was perhaps larger than Sabine assumed in her thesis.

It should be noted that the ratio of ED1 to the square of MD1 is a constant for a given m/q. 
The 5% discrepancy in this showed that we had 20Ne instead of 21Ne. We should incorporate the 
checking of this ratio into our tuning procedure.

ISAC had wrong amplitudes on DTL but had correct Prague Magnet setting, thus wrong beam right 
energy.

Other related points:

It is required that new thin windows be ordered for the IC. 

The DSSSD will be installed for the 21Na(p,g) run.

The beta-monitor is now hooked up to DRAGON scaler S9.

The ITW has not yet been hooked up for conditioning, which means possible delays in recieving 
radioactive beam.

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21Na(p,g)22Na RUN (CJ):

CJ presented her 21Na(p,g)22Na run plan to the group (see attachments).
Charge state distributions will be first in line before yield measurements are made.
It is intended to run the gas target at 4 Torr, and run on resonance as well as off-resonance
on the low-enegy tail.

A gamma_1 X gamma_2 spectrum is required to look for cascade transitions: this should be 
include in PAW++. Calibrations of the BGO array are required before and after the runs.

Extracting branching ratios will require a combination of BGO efficiency measurements and 
GEANT simulations.

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OTHER BUSINESS:

The upcoming 26Al run contamination measurements will require scaler histograms
in PAW++ online, for beta singles and coincidences in particular (Art & Jonty).

Joel's 32 spectrum limits won't apply in this case, so creating these spectra should be
straightforward.