Minutes of the DRAGON Meeting of April 29, 2003

Attendees: John D'Auria(JDA), Dave Hutcheon(DH), Dave Ottewell(DO), Joel
Rogers(JR),
Lothar Buchmann(LB), Sabine Engel(SE), Zhihong Li(ZL), Chris Wrede(CW),
Mike Lamey(ML), Chris Ruiz(CR), Catherine Neish(CN), Aaron Bebington(AB),
Shawn Bishop(SB), Dario Gigliotti(DG, recorder), Cybele Jewett(CJ)

Facility Hardware
1) DH reports that the side plates for the solid target are complete and
there is a possibility that the target will be ready for June
2) JDA started discussions on the possibilities of cooling the DSSSD. The
following points were made:
-cooling detectors may allow the use of previously damage
-ISAC water is not low enough in temperature to use for cooling
the Peltier device.
-we will not be allowed to use tap water, which is the correct
temperature
-ISAC water could be chilled but consideration will need to be
given to insulating pipes
-DO will look into the cost of a chiller
-we will also need to be cautious about condesation on the DSSSD
when we break vacuum

12C Experiment Update
1) LB presented updates on the 12C experiment
-see attached overheads for graphs and any other details missed in
the following points
-3 resonances are expected: 4+, 10keV wide; 4+ "narrow"; 2+
"broad"
-the first overhead graph shows that some points do not seem to
agree
-the elastic spectra seem to indicate that the resonances are
occuring at different energies than expected
-the suppression devices on the elastics are not working in all
cases
-some discussion took place as to what the satellite peak, a few
percent from the full energy peak, in the heavy ion concidence spectrum
might be
-the double peaking in the gamma coincidence spectrum is okay as
long as this is in fact angular distribution we are seeing
2) DH gave some discussion on issues of DRAGON acceptance for this
reaction. See overheads for details
-the probability that we are seeing the result of ground state
gamma events being clipped is higher than the possibility of seeing
cascade events being clipped
-the general idea is that because the cascade result in two(or
more) gammas moving off at different angles "the kick" imparted on the
recoils makes them more likely to go off at smaller angles and therefor
more likely to be accepted by the seperator. Ground state gammas give a
larger "kick" and may result in recoils with larger reaction cone angle
and may be clipped.
3) JR presented information on his analysis of angular correlations in the
12C experiment
-there are holes in the theta plot due to beam lines as well as
where detectors have been pulled back.
-plot of cgamma(theta) should be symmetric except for where
detectors 2 and 3 have been pulled back
-phi plot shows gaps a large pumping tube and at 45 and 135 due to
geometry of BGO's
-z position for the angular correlations is calculated relative to
the r.f.
-JR determined that 100-200 coincidence counts will be needed for
analysis of the ground state transitions
-LB suggested 2+ resonance is well known and this should be
studied first to give a basis for more difficult cases

E824 Data Analysis
1)CN presented her work on the some of the other 21Na resonances
-overheads will give more details
-there is a discrepency between what is calculated for omega-gamma
using data and what the result would be from simulation
-calculations are very sensitive to choice of threshold and this
must be considered when looking at the discrepency
2) SE also gave information on her independent analysis of the 21Na
resonances
-overheads show details
-there were differences in normalization techniques between the
two methods and this will be discussed by CN and SE
-there was also a factor of four difference in the value of
omega-gamma calculated by SE. This point will also be discussed with CN