DRAGON Group Minutes   6 May 2008
 
 Present   DO(rec) DH CD LE SF PB CV LB GR UH PM
 
o Preparation for Weekend Run
  Cool H target on Wednesday
    Load gas on Thursday
    Apparent window failure on Ion Chamber was explained by a 26 T interlock when attempt to go to 30 T was made
 
     Cyclotron has stripper failure so there will not be radioactive beam next week
 
o Status of Detectors
  MCP are working although alpha peaks are hard to see as noise is large
     NaI (HPGe? - ed)  stand needs stiffening.
  23Mg(p,gamma)24Al   Measure Charge State distributions of Mg & Al
  27Al(p,gamma)28Si 
 
See attached run plan
 
Next weeks beam from Thursday  24Mg(p,gamma)25Al

run plan  27Al   May 7 - 12, 2008

The primary goal of this beam time is to measure charge state distributions at the relevant recoil energies for the 23Mg(p,g)24Al experiment and to calibrate
the DRAGON end detectors (IC and local TOF).  Additionally we want to test the attenuator in front of the gas target and to perform a commissioning run for 
the local TOF at low energy (~200 keV resonance).

The energies of the resonances of interest are:
(considering energy loss in 8 Torr H2 gas and putting resonance at the center of the gas target)

Ecm (keV)    Ebeam (A keV)     Erecoil (A keV)
733          777               714 
652          693               636
497          509               467

For each recoil energy we do the following:

1)  let Marco/ops tune beam trough empty gas target, check alignment and transmission
2)  measure CSD at 0.5, 1, 2, 4, 8 Torr 
3)  tune beam to the end (FCF   ----    note:   MCP0 should be out !    ----   )
4)  ask ops to attenuate beam to ~100 cts/s
5)  optimize end detectors (IC and MCP detectors)
6)  take a longer run, note all settings (IC gas pressures, HV, gains, delays etc.)
7)  test the DRAGON attenuator (attenuation factor, energy deterioration, scattering, beam spot)

note:  
beam current should be around 10 nA on FC4;  
at the highest energy we want the smallest energy spread for testing the optimal timing resolution of the local TOF setup (which means the buncher to be on);
CSD measurements and attenuated beam runs shouldn't take longer than few hours per energy.


Once the CSD measurements are done we go to a resonance in the 27Al(p,g)28Si reaction (Ecm = 196 keV;  wg~14ueV) to test the recoil identification with the 
local TOF at low energies.

1)  tune through the gas target and the spectrometer in a standard way  (Ebeam = 213 A keV)
2)  take attenuated beam run
3)  switch to recoils
4)  take a longer run until we see the separation between recoils and leaky beam (expected count rate ~ 200 cts/day at 10 pnA)



For the 24Mg beam time  (May 15 - 17) we plan to do similar things except that the low energy resonance is at Ecm = 214 keV (Ebeam = 235 A keV) with a wg 
of 10 meV.