Minutes for DRAGON meeting, January 18th, 2005, 10:30.
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Present: CR, JDA, MT, WRH, GR (recorder), MP, AO, LB, JP, JC, DH, DO

1. Minutes of meeting of  Jan. 11, 2005  (circulated previously)
  - Nothing to correct on the previous minutes.
  - Volunteers are still needed for shutdown jobs in areas of high radiation fields. Contact VJ.
  - REA for second MCP should be done. More details are needed and an
    agenda should be made.

2. DRAGON Hardware
  - Upstream dipole
    A dipole has been installed to bend the beam to ISAC II.It has
    with very small beam pipes and these may cause us grief for our beam.
    

  - Beam monitor (CR)
    [see attachment "beam_monitor.pdf"]
    Purpose of the beam monitor is to quickly see whether we have the
    right atomic beam rather than a molecular mixture as it happened
    last Nov. (see Nov. 30 minutes). At the moment, there is no way to
    check this until the beam is tuned through DRAGON, and a half day
    of beam time is lost.
    The monitor measures the beam particles scattered backwards on a
    heavy target. The particles are identified by their different
    energies. The monitor could be placed behind the stripper.

    The LEDA is just an example used in the simulation since it covers
    a large angle. Dead layer effects are included in the simulation.
    The resolution is limited by the dead layer straggling and the
    kinematics.
    JC suggests to measure in forward direction when using a RIB since
    we need higher counting rates.
    Chris will prepare a presentation for the ISAC science forum in two weeks.

3. Projects in Progress
  - IC upgrade (CV)
    [see attachment "IC-upgrade.pdf"]
    Previous set-up was designed for higher energies. For lower
    energies we need thinner windows. Silson offers an 5x5 array of
    3x3 mm^2 windows and an single 14x14 mm^2 window. PSI offers a
    larger (and thicker) array with a total size of 50x50 mm^2.
    LB: Big problem is the size of the window. It has to be at least
        twice as large as the beam spot.
    DH: Temporarily place a DSSD in front of the window to check the
        spot.
    JDA: Or use the MCP?
    LB: It's a bit away and we never looked at the local resolution.
    JDA: We have beam (presumably 26Al or 27Si) in June and have to
        decide very soon what detector we use. With the DSSSD detector and
        local TOF we can do the 26Al experiment

    CV proposes to divide the anode into 2-3 plates. The largest
    difference in the accumulated charge can be seen where the dE/dx
    curves cross. This is at 10 cm (half of the range) for 40Ca 40Ar.
    For 26Al and 27Si, this point is at 5 cm (1/3 of the range) and
    the separation is less efficient with two plates. For 26Al and
    26Si the separation line is back to 10 cm and a separation brings
    no improvement either. A separation is only possible with
    17 ug/cm^2 (or less) SiN windows.
    The conclusion is: If you want to separate isobars you have to
    use 2 plates, if you want to suppress leaky beam from recoils,
    one single anode is the better choice.

    We also have to order new pre-amps that can be placed in the IC to
    reduce the noise that dominates the resolution at the moment.
    AO: We should use the pre-amps from the Cat. Det. They are better
        and we already have them. CV will look in this. 

  - GEANT calculations (CR)
    [see attachment "geant.pdf"]
    CR applied the new more realistic geometry with bigger pumping
    tubes as it was used by Dario (page 1). He simulated the
    distribution of the gammas coming from the Ex = 11.52 MeV 2+
    resonance in 16O, (for the C12(alpha,gammma)O16 data).
    Page 3: The black curve is the transition to the 0+ ground
    state, the blue curve the transition to the first excited state
    6.0 MeV (0+), and the red curve from the first excited state to
    the ground state. Magnetic sub-states are not taken into account.
    A 50/50 g.s./cascade branching ratio has been used for simplicity.
    Due to kinematics, the energies are split in the lab. system, as
    can be seen on page 5/6.
    Pages 7/8 show the final (gaussian-folded) spectra:
    - the total (sum of all charges) gamma energy of all BGOs
      (black line),
    - the leading gamma spectrum (blue line)
    - the second leading gamma spectrum (red line).
    The total gamma spectrum virtually contains more g.s. gammas, but
    some of them are the sum of cascade gammas. This is the reason why
    this spectrum was confused with the leading gamma spectrum in the
    experiment (page 11) where a 80% g.s., 10% 6.9 MeV (2+) and
    10% 6.0 MeV (0+) leads to the best fit.
    On page 12/13 the correct spectra are compared with the simulation
    with 13% cascade (6.0 MeV plus 6.9 MeV) contribution. The result is
    close to the published value of 8% but further improvements must be
    done.

  - Electronics for DAQ
    CV: New DSSSD electronics from Munich. Advantage is a faster
        timing and multiplexed energy output. 
    JP: Disagrees and suggests our present approach should be kept.
	The group agreed.    

4. AOB
  - JC (and MT) made a trip to Seattle to establishe a collaboration with the
    Univ. of Washington. for E1027. MT gave a report at an earlier meeting.
    UW scientists (KS) are interested and send an official paper for this.

  - E995: Technical review next Tuesday.
    Important issues are:
      - Quality of the off-line ECR results in terms of the ionization
      - Safety
      - Scaling to online performance
      - Impact on staff and other programs

  - NIM paper: DH: 1/3 of the people responded.

  - 20Ne: MT was able to duplicate Daves' results.

Actions for the next meeting
    IC, GEANT

Meeting ends at 12:10