Minutes of the DRAGON Meeting, May 25, 2004  (MMP)

Attendance: MMP, DFOT, DH, CJ, LB, AO, ML, JP, GR, DG, MT, JDA, CR, Cv,
co-ops

1. Corrections to last week's minutes

    a)  in section "Other ...", replace 'momentum' by 'energy'.
2. FACILITY
    a)  DFOT described design of system to remove DASS on rails from
endstation, to allow ion chamber to slide in.
        *  parts are in hand
        *  hold-up is the detailed design and construction
    b)  DH mentioned puzlling items in recent data acquisition and
analysis
3. CJ reported on latest 21Na(p,g) run
    a)  ostensibly, E=1152 but evidence for 9 keV/u drift down with
time ?
        *  AO mentioned that gamma-time versus RF could show IF/HOW E was
drifting
    b)  showed figure (attached) of Eg(most E) vs Eg(2md most) for 6 run sum

    c)  showed strip detector E signal, singles and coincidences.
        *  some weird coincidences where there shouldn't have been

    d)  MT stated that at one point, nothing went into Elastic spectrum,
but rather seemed to be moved into strip detector channels
        *  chan 16,17 went into DSSD 8,9
        *  shows up on Heavy Ion spectrum
        *  speculations abound on cause
           -  not clear if it is hardware or software
        *  N.B.  problem appeared at high spill rates
4.  CR reported on 26Al runs
    a)  summary attached
    b)  tested with 26{Al, Mg, Na, ?}6+  beam
    c)  finally got 2h of 26gAl(p,g)27Si data
    d)  determined charge state distribution
    e)  showed simulated ICh anode spectrum
        *  Al and Mg peaks overlap
    f)  using beta-monitor system as mass split, showed decay spectrum of
ions stopped on slit
        *  demonstrates 1.45sec 26Na and 6.0sec 26mAl decay
           - estimated  26mAl/26Na ~ 9% (naively) count-rate ratio
           - (alternate analysis summarized in attachment)
        * discussion ensued on better way (if any) to detect beta+ and beta-s

    g)  showed IC1 vs IC2 energy plots for 26Mg and 26gAl+26Na (?)
        *  weird accidental coincidences in 26Mg beam
        *  no gamma coincidences with 26Al+26Na beam
           -  weird that 26Al ended up on 'wrong side' of 26Mg peak in ICh

    h)  saw  26Al(p,g)27Si   E=389 kev/u
        *  from gamma coincidences, estimate   wg~ 45meV
           - compare to 60 meV from LB's previous work

    i)  stated that next run should go to 1.5 MeV/u to determine beam
contaminants

5.  KO reported on 21Ne(p,g) at 275 KeV/u reanalysis of Sabines' work

    a)  charge state distribution was 5+ in thesis, but actually 4+
        *  measured during a brief run that 4+ was 49.5% and not 35% for
5+ in thesis

    b)  showed HI energy in thesis and recent run, where there is an odd
double-peak in recent data

    c)  thesis quoted  209+-35 meV
        *  with new Q distribution, ==>  132 meV
        *  'world average' around 82+-12

6.  JDA talked about Summer Running
    a)  run for CJ 21Na(p,g) E824
    b)  21Ne run for KO
    c)  26Al run for CR

7.  CV described AMS facility in Vienna

    a)  showed test of straggling through diamond-like carbon (DLC) foils
        *  0.6 ug/cm^2, 2.0, 8.0
        *  can be made up to 50mm in diameter  (in Moscow)
        *  proposed for MCP foil (?)

    b)  also result from 15nm (34 ug/cm^2)  Silicon Nitride windows
        *  for ion chamber ?
        *  can be made up to 17x17 mm^2 by Silson Co
           -  bigger sizes if thicker
           -  very uniform thickness
        *  extreme thinness reduces energy tails

8.  Meeting Adjourned 12pm