Minutes of the BEAST meeting
Friday June 12th 12:00 JST

  • DAQ:
    The Australians will lead the DAQ effort. Leon Moffitt and Ascelin Gordon will prepare and operate the system at KEK starting in September. Details of the Australian's plan will be discussed at the next meeting.

  • Drift tubes:
    Sanjay Swain and Olsen have been testing the drift tubes. Pictures of output signals from a Strontium-90 source on the oscillscope and the pulseheight spectrum from a multichannel analyser were shown. The final PCB readout boards arrive on Monday. Photographs of the signals and on-going detector work at Hawaii are available on bwg03:~sahu/beast/*.jpg

  • Diodes:
    UH summer students and technicians are making up the twisted pair cables. The diode boxes contain two diodes, Pb sheets, and an RTD. The internal components are assembled with superglue. On June 12th, diode calibration with the UH Cobalt-60 source began. The diodes will be irradiated with doses in the 0-500 krad range (doses of 10, 20, 50, 100, 200, 1000, 5000, 20,000, 50,000, 100,000, 500,000 rad will be measured).
    The importance of keeping the diode temperature relatively constant was emphasized. This is important to avoid shifts of the diode calibration and provide immediate feedback to the accelerator. We will try to install enough air conditioning inside the concrete shield so that the temperature is 25+-3 C at all times.
    Prototype PCB readout boards were ordered.

  • Structure:
    The concrete shield was shifted 10 cm by the IR group. Marc Rosen and Boris Shwartz have rearranged the CsI(Tl) crystal layout to accomodate this change. Other modifications are the use of non-magnetic materials (fiberglass, Al, plywood...) for all elements of the support structure. A new shelf for the diode and drift tubes amplifier was designed to minimize cable lengths. The structure will also support the beampipe.

  • Simulation:
    Bozek reminded us that the e+ beam profile in GEANT is wrong. The e- beam profile is correct. This may be a problem with either the TURTLE or GEANT simulation and should be investigated further.
    Funakoshi will provide a list of the masks and machine apertures to check the simulation. We also discussed changes to the machine optics with the BELLE solenoid turned off. The antisolenoid strength is 10% of its final value and QCRP1 is rotated. These changes will have to be incorporated into the simulation.
    The diodes on BEAST will be located at z=-203 mm, 0 mm, 255 mm. These positions correspond roughly to the maxima and minima in the particle background. The extreme values in z are close to the locations of the particle masks. It is important to check that these are the optimal locations with the GEANT simulation.