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    User name Kai

    Log entry time 02:47:54 on November 02, 2009

    Entry number 297137

    This entry is a followup to: 297076


    Yesterday, I said I found the path of bcm u3 which connects between counting house and detector hut is bad. However, it might be not true. Yesterday, I used my test pulse which is NIM signal, 20ns in width, to test all of the bcm scaler reading, and it works on both arms of u1,d1,d3 and the left arm of u3, but not on the right arm of u3 which is good in the counting house side. So I went to the right arm detector hut, and said the path connecting between the detector and the counting house was bad after I didn't find any signal on the scope there. However, Dianchen helped me figure it out today that it might be because that my test pulse is 20ns in width. Although it works in most of the channels, but for the path of right arm u3, it might has larger attenuation than others when the signal goes from cnt house to the detector end. Even if the amplitude is enough, the scaler still cannot read the signal if the width is so narrow. I then increased the width to be 500ns as what the real bcm signal does, and the scaler counting of the right arm u3 get back. Actually, the turning point is at roughly 100ns width.

    With this consideration, we'd better use the signals with large width if we want them to go from cnt house to the hall. So should we change the tagger width to be >100ns in the counting house side? The current one is 20ns.

    A copy of this log entry has been emailed to: xiaochao,rom,dwang,rsubedi,deng,pkpan