Dear 3rd Arm Colleagues,
During the period time of Nov 17 thru Nov 21, Malik, Lindgren, Bogdan, and a high school teacher set up 3 scintillators of thicknesses 1 cm ,10 cm, and 10 cm thick on top of the platform so that they subtended an angle of about 2 ms with respect to the deuteron cryotarget. The solid angle is defined by shielding the scintillators with 6 inches of lead in between the target and scintillators in such a way leaving a 10 by 20 cm opening to the detectors, which are about 3 meters from the target. The sides are shielded by 6 inches of lead except where the cables are connected to the phototubes on each end. An array of one inch thick lead plates shields the scintillators from above and below. The anode signal from each detector is connected to a patchboard which feeds the signal into the middle room in the Hall A counting house upstairs. The high voltage is also controlled upstairs. The three linear signals are each fed to a linear fan out. One output of the fan out is sent to a fast discriminator generating a timing signal. One of the fast outputs is sent to a TDC and the other fast output goes to a logic unit generating logic signals to define the gate for the data acquisition system. The other output from the linear fan out after appropriate delay goes to the ADC. Bob Michaels help get this going. Jeff Templon also wrote part of the data acquisition system. The stand alone data acquisition system is not quite debugged. We will be able to take data parasitically , plot any ADC versus any other ADC, plot any TDC versus any other TDC and put cuts on the energy and timing signals. Present plans are to get the data acquisition system working properly and take some preliminary data parasitically with the present set up during the week of Dec 15. We welcome you to help take data during this time. I am in the process of putting up a photograph of the set up on the web. It will take a little time.
RAL
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Send comments to: Richard Lindgren
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ral5q@virginia.edu