Minutes of the BEAST meeting
Wednesday September 9th 11:00 JST

The installation of the BEAST frame at KEK was completed. The system test of BEAST detectors at Hawaii was finished.

  • Schedule:

    Haba reported on the last KEK-B meeting. The delays in vacuum pipe delivery have been resolved. Now the item on the critical path are the septum magnets required for beam transport from the linac to the main ring. The first one will be ready in late October and the last one in late November. This delay for delivery of these magnets could lead to a one month delay in startup of accelerator commissioning (mid-december). The leaders of the accelerator division are working hard to find a way to expedite the delivery of these magnets from the company and avoid this additional delay.

  • Commissioning strategy:

    There was then a discussion of how to handle the bakeout period where large radiation doses are expected. A proposal is given below:
    1) Install the full BEAST including the SVD quadrant on the beampipe starting next week.
    2) Debug BEAST readout and DAQ as soon as the first low current turns are accumulated at KEK-B.
    3) As the beam current increases, (around 100 mA) measure radiation dose and background levels. If the radiation dose is not acceptable remove BEAST. Wait until high current bakeout is completed. Then reinstall BEAST. Otherwise, if the dose during bakeout is tolerable, continue with BEAST in place (and possibly turn off power to the diodes and SVD quadrant.)
    Since the mechanical installation takes 1-2 days, this plan is very flexible. In addition, it will get BEAST readout debugged, provide better feedback to the accelerator.


  • Structure and Construction:

    Rosen, Haba and IHI completed the installation of the beampipe support and BEAST frame at the interaction point. Extra bracing was added to make the structure rigid to better than 0.5mm. The CsI(Tl) shelves are assembled and ready to be installed.

  • System Test:

    Sahu reported on the system test of the BEAST detectors. About half of the diodes require conditioning with power on. The leakage currents go down from 30 nA to around 2 nA after conditioning. Drift tubes tests show that one tube out of 53 cannot hold high voltage. There was a mistake in mechanical assembly of the quadrants for the system test at Hawaii. This will be corrected at KEK. The location of the amplifier boxes for the drift tubes and power distribution will be simplified when the detectors are installed at KEK.

  • Simulation:

    Yamamoto reported on work with TURTLE. He has now resolved a long standing problem, the discrepancy between the beam size in the TURTLE simulation and the SAD calculation. This problem and other related problems are due to having neglected dispersion in the TURTLE calculation. See his e-mail.

  • CsI(Tl):

    Zhilich presented a proposal for CsI(Tl) DAQ which is available in an earlier e-mail message.

  • DAQ:

    Gordon and Moffit have arrived at KEK and have begun work.