Minutes of the BEAST meeting
Friday July 31st 12:00 JST

  • Schedule:
    Haba reviewed the implication of recent events for the schedule. In the course of the KEK-B workshop, it become apparent that the original Oct 15th date for the startup of commissioning was unrealistic. The BELLE and KEK-B leaders are now revising the schedule and considering two options:
    1) KEK-B commissioning starting around mid-November without BELLE. This plan would involve no changes in the plan for BEAST.
    2) KEK-B commissioning starting around Dec 10th with BELLE rolled in. This plan would involve modifying BEAST to fit inside the CDC as had been originally planned before the CsI(Tl) crisis.
    Option 1) has more flexibility for the accelerator but does not allow commissioning with solenoid compensation.

    Whatever the final choice, the EFC installation can continue as originally planned. Sahu and Rosen will come to KEK in early September for a "dress rehearsal" of BEAST installation on the beampipe. The Australian students (Moffitt, Gordon) will delay their arrival at KEK until the beginning of October for BEAST DAQ.

  • DAQ:
    Tests of the DAQ system were carried out sucessfully at Melbourne. Moffitt reported that the MOSFETs were read out with the IOTECH data logger. Gordon reported that the LINUX based CAMAC DAQ system was read out successfully at 1 kHz.

  • Diodes:
    The final readout boards arrive on Tuesday. The MOSFETs were shipped to Hawaii. The temperature calibration of the diodes is complete. Sahu reported on the radiation dose calibration study. He finds that after the initial dose there is time dependent "annealing" and the dark current has two components. One has a fast decay time (minutes) and the other has (1 week) time constant. The overall signal decreases by 30% after exposure to 250 krad. The depletion depth appears to decrease by about 30% at 150 kRad. Temperature calibration also changes at large dose.

  • Structure and Chambers:
    The drift tube quadrants for the inner BEAST are almost complete. Rosen is investigating modifications of the end-rings and cable bulkheads required to install the inner BEAST in the BELLE drift chamber. The SVD quadrant fabrication will start soon. The drift tubes for the outer BEAST are now complete.

  • Chamber Calibration:
    Sahu made an EGS4 simulation of Co-60 gammas in the drift tubes. The spectrum from the real data will be normalized to the simulation, and will be used for gain calibration. Cosmic ray calibration seems unrealistic because of rate problems, and this method looks promising.

  • Background Simulation:
    Bozek solved a long standing problem. There was an error in the B_r field component in GEANT. After correcting this problem the beamspot looks physically reasonable but is still too large at the IP by a factor of 1.5 in x and 5 in y. This remaining problem may be associated with the treatment of skew quadrupoles in the TURTLE part of the simulation.