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    User name A. Camsonne

    Log entry time 18:46:27 on August 25, 2009

    Entry number 285969

    keyword=Compton electron detector noise study and tests

    I added the ferrites with the help of Jack this morning, I haven't really seen a major. I might have found an interesting correlation. Noise if bigger when at lower threshold indicating still a bit of crosstalk. So when going down from 17 to 13 or 10 the noise increases which could explain the lack of major improvement of efficiency when lowering the threshold. I think one possible fix could be to use only the lower part of the detector and put a metalic plate instead of a discrimator board as additionnal shielding. I will check that tomorrow during the pass change.

    I also try to ground a bit better the right side but have not seen major changes so far. When it is quiet background is still aound 14 mV. So better grounding shielding could still help.

    A copy of this log entry has been emailed to: brossard@clermont.in2p3.fr,hyde@jlab.org

    Figure 1 With ferrite

    Figure 2 Without ferrite

    Figure 3 Threshold of 10

    Figure 4 Threshold of 13

    Figure 5 Threshold of 200