Minute of the CDC Group Meeting held on 26-Apr-01 (15:45-18:00 at Fuji-F2)

• Date and Place
  April 26(Thursday), 2001 at KEK-Tsukuba (Fuji-2F)

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• Attendants
  M.Kobayashi, H.Okuno, T.Yoshida, N.Khalatyan, K.Fujii, O.Nitoh, H.Kuroiwa, K.Hoshina, H.Hashiguchi, T.Hayasaka, M.Araya

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• Contents
  • 1)Report on the present status(T.Hayasaka)
    He is going to take over the work of Sakieda-kun, i.e., study of interference between two avalanches using parallel laser beams and the baby chamber. Things to do as a first step:
    • a) search for an appropriate material to replace the quarts window of the baby chamber which may cause scattering of the laser beams.
    • b) measurement of the wire gain of the baby chamber as a function of sense-wire high voltage.
    • c) measurement of the laser beam profile.
      • *) The mechanism of laser beam scattering by the quartz window is not understood.
      • *) The chamber signals looked more structure-less before. => To be studied.
  • 2)Report on the present status(H.Hashiguchi)
    He plans to construct a VME-based DAQ system. A VME FADC prototype module and a VME CPU board will be available by the middle of May. Things to do then:
    • a) Tests of the FADC performance.
    • b) Installation of linux on the VME CPU board.
      • *) What happened to the VME crate controller and the PC purchased before? => To be checked.
      • *) RTlinux (Real Time linux) should be installed since ordinary linux is too slow for online processing.
      • *) FADCs of the next version will have some intelligent functions such as zero-data suppression.
  • 3)Cosmic-ray measurement(H.Kuroiwa)
    • a) Measurement
      Cosmic ray tracks were collected with the baby chamber to study the influence of O2 contamination on the chamber performance (charge attenuation, wire efficiency and spatial resolution). The oxygen concentration was controlled using an oxygen-premixed CO2 gas.
      • Some of the obtained results (ps-files) are placed at jlcux1: /proj/cdc/users/kuroiwah/PS-file/meeting:
        • a) Charge attenuation as a function of drift distance.
          • i ) cosm050_Ph02.ps ( 50 ppm)
          • ii) cosm120_Ph02.ps (120 ppm)
        • b) Wire efficiency as a function of drift distance.
          • i ) jsf0712.Eff03.ps ( 50 ppm)
          • ii) jsf2306.Eff03.ps (120 ppm)
    • b) Next plan
      He will write the first draft of a paper on the performance obtained with the baby chamber to be submitted to NIM.
      • *) What are those small signals populated in short drift distances? => to be checked.
      • *) The life time of drifting electrons should be estimated from the charge attenuation.
      • *) The charge attenuation in long drift distances observed with the 4.6 m chamber can thus be ascribed to oxygen contamination.
      • *) The oxygen concentration in the baby chamber can not be reduced to less than 20 ppm because of its limited gas tightness.
  • 4)Simulation program development(K.Hoshina)
    Geant4.3.1 is now running on MacOSX. See http://www-jlc.kek.jp/~hoshina/cdc/geant4/.
    • But there are some problems:
      • a) Bugs (found so far)
        • i ) G4Tubs.
        • ii) Decay table of particles are deleted after grandchild particles.
      • b) Endless loop
    • Things to do:
      • a) Fix the problem of endless loop.
      • b) Make examples for other subgroups.
      • c) Remake the analysis program.
  • 5)Papers to be submitted to NIM(H.Okuno)
    • a) Corrections and comments on the drafts are welcome (by the middle of May).
    • b) Requests for further analyses:
      • For the paper on dE/dx
        • a) Pulse shape simulation using GARFIELD => Norik-san.
        • b) Most probable energy losses given by Landau-distribution fitting rather than by truncated means => Hayasaka-kun.
        • c) dE/dx vs. beta-gamma => Kobayashi.
      • For the paper on space charge effect
        • Simple estimation of the effect => ?
    • *) Several numbers in the drafts should be checked on reference to the log books.
  • 6)ACFA report(N.Khalatyan)
    • a) Topics to be filled with the help of Okuno-san:
      • a) Particle identification using dE/dx.
      • b) Space charge effect.
      • c) Two-track separation capability.
    • b) Spatial resolution of the baby chamber? => Kuroiwa-kun.
    • *) The next deadline is the end of May.
    • *) We are going to use the name "baby chamber" officially henceforth.
  • 7)Others
    What shall we do in this fiscal year? => going to be a subject of the next meeting.
    • *) Every group member should think seriously about what needs be tested or confirmed before the design, construction and operation of the real chamber.