Minutes of DRAGON meeting, 14 February 2006.

Present:  Chris Ruiz (CR), Christof Vockenhuber (CV), Dave Hutcheon (DH), 
Dave Ottewell (DFOT), Dieter Frekers (DF), Goetz Ruprecht (GR), Jac Caggiano (JAC), 
Jonty Pearson (JEP), Lothar Buchmann (LB), Peter Machule (PM), 
Mike Trinczek (MT) - recorder.


1. Previous minutes:

JAC would like there to be clarification on the results of cleaning an old DSSSD.  
Quantitatively, how much of the reduction in leakage current is due to the cleaning
and how much was due to the cooling of the detector?


2. Alpha-acceptance tests:

JEP presents overhead (see Attachment) of the latest results for the detector 
positioned at TP7.  On the overhead, the bottom 2 lines summarize what is important 
and should now be compared to GEANT (which CR is doing).  They show an acceptance 
of ~21 mrad for the alpha source positioned at target centre.  This agrees with the 
21.6 mrad acceptance calculated purely from geometry.

New detector position is just after MD1.  Encountering EPICS problems and noise 
problems from the charge slits.  Tinfoil shielding helps.  The noise is probably 
due to the holding current on the charge slits; will investigate.


3. GEANT:

CR has updated the small pumping tube coding within GEANT.  He has now run a 
12C(a,g) simulation for the low 4+ state and gets the same acceptance as before.
So, this has been ruled out as an explanation for the apparent 40% deficit in
our S-factor versus that of Rolfs.  We must look for other things...

CR will now update the large pumping tubes and repeat simulations.

DH mentions that the Strasbourg group (16O+12C) are also having GEANT difficulties.
MT's first cursory glance can find nothing wrong...


4. Draft of 21Na(p,g) paper from CSM:

DH is asking for comments from the group.

MT has already pointed out the discrepancy between the Energy levels in the draft
and the "DRAGON-accepted" values in our PRC.  This may be resolved if Uwe and
Cybele use the correct Q-value for the reaction.

MT also notes that his quick, prelim wg analysis from 2 years ago on the levels at
~1100 keV differs by ~15% from that reported in the draft.  Uwe will try to dig
out the calculation (normalization differences??) since Cybele has moved on to
a post-doc...

CR is concerned about the BGO efficiency that was used.

DH will attempt to locate a copy of Cybele's thesis in hopes of gleaning more
information on how the analysis was done.


5. AOB:

CR will give a talk at Banff and at the APS Northwest meeting in Tacoma
(http://www2.ups.edu/physics/NWAPS2006/home.htm)
Heather Crawford will also present at Banff.

DH confirms that DRAGON will have 2 summer students this year.

GR will also submit an abstract to NIC IX for the 22Na "Rolfs Effect"
measurement.

A draft schedule for RIB is now out and will be discussed at the Science
Forum.  DH is working on the OLIS schedule.


6. Items for next week:

GR will give a short presentation on Screening.

JEP will update us on the alpha-acceptance tests.