Minutes of the BEAST meeting
Friday June 5th 12:00 JST

Refinement of the BEAST mechanical design for operation as a standalone device inside the concrete radiation shield was discussed. An extra radial layer of drift tubes and CsI(Tl) crystals will be added.

  • Simulation:
    Keith Hamasaki (UH graduate student) and Jorge Rodriguez have begun defining the geometry for a GEANT simulation of a standalone BEAST. The mask geometry was extracted from the GSIM of BELLE. Bozek noted that the beampipe should be modified. In BEAST it will be 1mm thick Al rather than thin Be.

  • Drift tubes:
    Have succesfully tested the prototype PCB readout board. A block diagram and list of properties is shown in ~browder/beast/tube_readout.ps on bwg03. The DC signal has a gain of 22 mV/microamp. The DC output level will be in the range -10 V to + 10 V. The PCB design is about to be submitted. The final boards will be populated at a rate of 3/day by students and technicians. The drift tubes should be finished by the beginning of July.

  • Diodes:
    Two prototypes were required for the readout board. We will probably only measure the leakage current as was done for the BABAR commissioning diodes. The final PCB board should be back before the end of June. All the readout boards will be populated by the end of July. Testing of the available diodes will be going on in parallel.
    The layout of the mechanical holder for the diodes was finalized. Recall that in order to distinguish SR and lost particles, there are two diode layers separated by Pb. There is also a RTD in the sandwhich for temperature calibration. The mechanical layout is shown in ~browder/beast/diode_mechanical.ps on bwg03.

  • EFC:
    Ueno showed drawings of the partial EFC that will be installed at the time of commissioning. There will be 4 3 x 3 arrays in both the backward and forward directions or a total of 36 crystals in each direction. Dose monitoring devices (TLDs/MOSFETs) will be needed for both the EFC and CsI(Tl) crystals.

  • Structure:
    Rosen presented a new concept for the mechanical structure which incorporates the constraints of the concrete radiation shield, the 15 CsI(Tl) crystals and the additional radial layer of drift tubes. After discussion, it was decided that the new layer of about 24 drift tubes will be uniformly spaced in phi. The CsI(Tl) crystals will be supported on shelves that can be adjusted in dip angle. There will be test crystals that correspond very roughly to the locations of the barrel and endcap crystals. Because of mechanical constraints from the concrete shield, these will be closer in radius than the BELLE barrel crystals. A table to hold the diode and drift tube PCB amplifiers will also be designed to fit into the structure. More details of the SVD quadrant in the BEAST structure, which now has three layers, have to be worked out as well.

  • Testing:
    There are no fixed target test beams available at KEK until next year. BEAST testing and debugging will be done with cosmics and sources.

  • DAQ:
    Discussions with the Australians are ongoing. It was noted that LABVIEW which is used for testing of diodes/drift tubes at UH cannot accomodate high rates. A UNIDAQ like system such as that used in the TOF and ACC beam tests is a possibility. Other existing DAQs may also be copied or used. More input and discussion is needed.
    The file ~browder/beast/daq_require.ps shows Sahu's first pass at a channel count for DAQ and cabling. Digitization of the pulseheights from the tubes may not be necessary. Connecting a few channels to a multichannel pulse height analyser will probably be sufficient to diagnose the presence of SR X-ray lines. This will ease the CAMAC module requirements. It is also possible to readout subsystems (e.g. CsI, diodes, tubes) independently.
    Sakai noted that we plan to send only one or two background signals to the accelerator control room. On the other hand, we will need to extract a great deal of information from the accelerator database.