Meeting minutes Tuesday 17th June 2003

Present: DH, MA, CG, CJ, CR, AL, AB, PM, LB, ML, DG, AO, ZL, AOli, CW, 
DO, SB
Recorder: JK

Previous minutes accepted


1. Hardware status.

    Cooler:  Working well.  Is able to cool from 27 - 5 (degrees) in 
    20 mins.
    CW would like a check for condensation outside of the vacuum box at 
    low temperatures.  
    Plan on running the cooler at all times, even with new detectors.

    Leak detector:  Detector is here but cart hasn't arrived yet.

    ED trips:  There have been strange trips lately.  
	       Three courses of action are:
               1. Turn power off and on at the power supply.
               2. Set current limit to 0, then to 40 on ED Experts page
               3. Try to restore the PLC memory:  unplug Canbus into
                        ED control temporarily (ask Ops how)
        
    MCP was shorting due to broken wires.  Was taken out and is now
    back in.


2. Wobbler studies.

    MA presented report on his wobbler study.  Used 20Ne beam of
    0.2MeV/u. Did SM0X scans for dE/E tunes of -4%,-3%,0%,3% and 4%.
    Did SMOY scan and Energy scan.
    Losses occur between FCCH and FCM. Tried to move beam, by making
    it under-bent at MDI and using SM1X to bring back to position on
    BCM2 but it didn't increase acceptance at FCM. Using SM1X and ED1
    to dog-leg left at BCM2 didn't increase acceptance, either.
    Plans: Do further testing. Try to change the front quad tunes,
    to shift the focus downstream to make envelope through the
    Q3/4/5 triplet smaller. Try to confirm if a focus
    is at XLITC and SLITM.

3. Analysis results.
        
    BGO calibration results: DG presented his report.  The
    pulse-height spectrum for a Cs source and 3x3 Nai detector
    has counts above the main peak due to pileup.  Unsure on how to
    correct for this: used the formula shown on attached figure.
    Cs source + NaI detector efficiency vs source distance: now get
    good agreement between data and GEANT and vs Marion
    & Young curves.  
    Sources of error in the data is from fit errors and source activity
    uncertainty.
    Measured 21Na 1.275Mev peak efficiency is also in good agreement
    GEANT, Marion&Young.  Now have confidence that the strength of the
    4.43 MeV source can be found using NaI and GEANT.
    Things go well for a single BGO, but pileup gets complicated with
    the array.
    Some strange asymmetries were seen with source data, e.g. more
    counts in the Left side BGO's than into the Right side BGO's.
    
    21Na(p,g) update:  
    The one "decent" run on the 460 keV resonance showed no events
    with the proper combination of recoil energy, TOF, and gamma
    energy.  It would be worth re-doing if time becomes available
    at the end of June (contingent upon the HEBT3 experiment not
    needing all their assigned 21Na beamtine).