DRAGON MEETING MINUTES - All Hallows Eve, 2006

Present: PM, CR (Rec), GR JP, MT, CV, DFO, DAH, JDA, LB, AH

1. Hardware

o One of Varian IGs needs repaired. PM to talk to Vacuum Group to see about 
modifications. 

o Beam stops tomorrow (Wednesday), MT and DFO to go to Mass Sep room to look at 22Na 
targets.

2. Alpha Acceptance

o DSSD at mass slit box, YSLITS removed. DSSD 3mm lower than optic axis.

o JP shows hit-patter projections, source at 0, -2mm and +2mm in y, at gas 
target z,x center.

o GT exit aperture was removed.

o Acceptance max at +2mm, suggesting gas target is lower than optic axis.
 
o Next step: more GEANT calculations.

o How to fix? Raise whole target (everything supported by yellow framework) + 
check collimators.

o JP and CV suggest collimating source to look at on-axis alphas with Quads on 
and off, but it was commented that rate would be extremely low. 

o Perhaps temporarily move gas target and assembly up for tests with beam?

o John: Jac was at PNL and mentioned actinides for potential strong alpha source. 

3. 20Ne(p,g)21Na

o Will be running this weekend, starting Friday. Objective: why do our 
20Ne(p,g) results for the 1162 keV resonance differ from our own measurement and 
literatue?

o Will be running owl shifts. 

o Do we need another resonance for comparison?

o CR: there are 21Ne+p resonances at 667 and 730 keV that are strong and under 
the target width.

4. 22Na lifetime Expt.

o Rolfs paper is out in European Journal Phys. Claims change in 22Na lifetime. 
They measured 2 days at room temperature then 3 days at 12K.

o The ratio of rates claimed is 1.2+/-0.2 %

o 7Be and 137Cs were reference sources.

o Goetz's measurement: 511 rate strange, correlated to cyclotron starting up.

o Compressor on/off affects reference source position - mechanical stress - 
but always moves back to same spot. Do we know this for sure?

o No change seen at all in our measurement despite better stats and better control.

o Improved experimental design is underway.

5. AOB

JDA brings attention to papers on 23Al decay regarding 23Mg states.