User name jroche
Log entry time 11:38:31 on October30,2004
Entry number 135403
keyword=bcm scan this morningWe took data with beam current varying from 1 uA to 20 uA in order to study the HRS rates variation as a function of beam current.
The list of runs is given in the attached file 1, the data are extracted from the end of run summary.
The figure 2 shows some preliminary results (using the real rates- not affected by deadtime- and the reading BCMu10) :
-top left : events per nC as a function of the beam current
-top right: events per nC as a function of the beam current normalized to the 'rate' at 20 uA
-bottom left : the smart RC suggests that we correct by the rate of cosmics. We measured cosmics rates opportunistically during a tune period 9no beam, run 4201, 14.3 Hz ts1, 10.8 hZ ts3 to be compared to 3.3 kHz ts1 and 0.4 kHz ts3 at 2.5 uA). With this correction, the two hrs 'rates' vary similarly.
-bottom right : the ratio of the two hrs rates on the former plot.
From this one may conclude that either
-the target density decreases with beam current increasing OR
-the bcm gain is slightly off
I'm not sure about the importance of the raster size variation during this data taking if the goal is to calibrate the target density variation.
FIGURE 1
FIGURE 2
