Minutes DRAGON Meeting Wed. Nov 12/03
14:30 ISAC Conference Room

PRESENT: MMP(recorder), JDA,LB,DH,MT,DFOT,NC,JR,CJ,JP (Jonty),ML,CD,AB,
  DG,CR,York guests (David Jenkins and Simon Moon)

MEETING STARTS 14:33

1. Minutes of Nov 4 meeting (as corrected and distributed by JDA)
approved.

2. Acceptance fluctuations in 12C+a-->g+16O (again)

  	o Lothar reported on weekend run ostensibly done for Q1,Q2 scan
	 o E = 1.46 MeV/u (?) and I~40pna
  	o heavy ion recoil spectra taken  at standard 0% (tune of DRAGON) setting
  	  after each step of quad scan changes
     - SHOULD get same centroid and normalized yield each time
     - HOWEVER yields, centroids varied a LOT !!?? (figure)
	 o LB speculated that only a few keV energy shift could account
  	   for the variations, since we were running on/near a resonance
  	o JR showed TOF spectra from these runs (figure) which indicated
  	   a 1.1% down energy shift (~8ns) monotonically

     o ACTION ITEM
      - __will need to give this matter consideration for future runs

3. Germanium detector test

  	o borrowed from Gordon Ball (?)
  	o "heroic" effort by JR, DG and others to get it working
  	o calibrated with Cobalt source (E= 1.1 and 1.3 MeV)
	o Good news: survived heat and vibration in tgt area
  	   and at least some data were taken (figure)
  	o Bad news : data inconclusive. resolution not as good as
  	   hoped. sparse evidence seen for lines expected. (figure)
  -    run wasn't very long
  	o Discussion about whether data acquisition was set up optimally
  	   and what improvements could be made

4. 12C + 12C --> 24Mg + g solid target run

  	o DJ of York outlined history of this reaction
  	o Ecm=8MeV, 10pna for ~12h for test gamma-(A=24) coincidence
  	o initial results this week during test running look "reasonable"
     - gamma energy consistency checks OK (figures)
     - e.g. sum of energies <22 MeV (as expected)
  	o Discussion about calibrating BGO at large Eg
     - could use 12 MeV gamma from 23Na(p,g)
     - would prefer a 22 MeV gamma, but one can bootstrap up
  	o CD showed HI recoil spectra
     - evidence for g-HI random coincidence with alpha background
       (figure)

5. JDA showed run sheet devised by NC
  	o layout corresponds 1<-->1 with various EPICS control pages
     - clearer than old sheet (figure)
      o ACTION ITEM: FILL THESE OUT DILIGENTLY !!

6. MT discussed Geant3 simulation briefly

	o implemented new target collimator tube geometry

7. JR showed analysis of 12C(a,g) recoil detector data
  	o noise correlates with gas pressure/beam
    - ionization trail to target ?
  	o noise has slower risetime
     - suggests pulse-shape discrimination to suppress it
  	o JR used a 2nd delayed LE discriminator circuit for PSD
  	o elastic pulse height moves around
     - likely effect of noise which fluctuates
  	o TOF (TDC27) signal shows reasonably clear separation of
  	   noise and true recoil peaks (figure)
     - sometimes peaks overlap a little
  	o at this point can't use recoil spectra for normalization
  	o speculation that adding a suppressor grid in target plus
  	   new TDC27 circuit could clean up elastic TOF spectrum

MEETING ADJOURNED 15:42