Minutes of BEAST meeting
Thursday April 16th (8:00 a.m. JST)

  • Background simulation:
    Sahu has nearly completed the high energy ring (HER) DECAY TURTLE calculation with the new lattice. He is checking alphas, betas, beam sizes for the 150 lattice elements through which he tracks off energy particles. The background appears to be much lower than for the last lattice but this needs to be checked in detail.
    When the DECAY TURTLE part is finished, Bozek will take it and incorporate it into the GEANT simulation of BELLE. Sahu and graduate student Sanjay Swain will optimize the positions of the moveable masks. The approximate locations of the moveable masks are now known from communications with Toge and Haba.

  • Sources:
    Haba-san has been looking into calibration sources. Cd^109, t_1/2=462 days, which decays via e- capture to Ag^109 with the emission of 25 KeV x-ray is the best candidate. The X-ray should be transmitted through the Al in the proportional tubes. Haba and Sahu will calculate the necessary strength to achieve a few Hz counting rate in the tubes. The proportional tubes are 0.5" diam (1.27 cm) and 20 mil (0.0508cm) thick. Location and the number of sources is still to be determined.

  • Structure:
    Marc Rosen (UH engineer) is working on the mechanical drawing and design. Haba is worried about checking the consistency with the drift chamber endplates and other mechanical constraints. A trip to KEK by Rosen to check out the mechanical constraints for installation and his presence at the time of BEAST installation was strongly requested.

  • Information from KEK-B
    The issue of pressure bumps was discussed again. The pumps are connected in series in 15-17m sections. Some discussion is required with the accelerator group so that individual pumps can be turned off to make local pressure bumps in order to diagnose sources of beam background.

  • Schedule on subcomponents:
    Diodes:
    100 Hamamatsu diodes have been ordered. Graduate student Yong Li will begin the radiation and temperature calibration of the diode/thermistor packages at the UH Papaya Irradiation Facility when the diodes arrive at the end of April.
    Proportional Tubes:
    Tubes have been ordered
    MOSFETs, CsI(Tl), EFC:
    No news
    SVD:
    On schedule. Ladders in May. Electronics will be ready by August.

  • Installation:
    Current plan is to install BEAST around August 10, 1998.

    Next commissioning meeting: Thursday April 23 (8:00 a.m. JST)