Target and X-ray detector considerations in low-duty and intense pulse electro-channeling experiments

The use of the Stanford Mark III electron accelerator presents special difficulties for channeling experiments due to its low-duty factor pulses. To compensate for the low-duty cycle of the channeled electron beam, the author utilized the high average current generated by the accelerator and analyzed the X-ray output using a turnable X-ray monochromator and a semiconductor detector operating in the current mode, rather than in the normal pulse mode. Cooling of the specimen was achieved by using a copper cooling rod to remove the dissipation of 10 W into a liquid nitrogen heat sink. The nonlinear efficiency of the monochromator over its full range of 5-30 keV was compensated by controlling the scanning rotation speed using a minicomputer-controlled stepping motor