The Johns Hopkins University
Applied Physics Laboratory
April 3, 1978

Dr. T. P. Armstrong
Department of Physics
University of Kansas
Lawrence, Kansas 66044

On 27 March 78, I ran a dead-layer test on the spare d detector.*   SMK suggested I send you a copy of the results.

The detector, itself, is one that ORTEC made as part of the same batch from which the detector in the a location of VOYAGER-1 came. The test, using electrons and protons from the GSFC accelerator, was basically the same as Ted Fritz described in Appendix E of the JOP proposal. The pulse-height-analyzer and pulser were calibrated using the 59.6 KeV x-ray line from Am²⁴¹ in our b detector.

The actual results of the test are shown on the accompanying figure. Our detector, which ORTEC listed as having 40.1 mg/cm² Al, is presented by the closed circles. The open circles are data given by Ted Fritz in the JOP proposal for an off-the-shelf ORTEC detector with 40.2 mg/cm² of Al. The similarity suggests we have a good data set here, although the results do not lead one to a great deal of enthusiasm.

Sincerely,

J.W. Kohl

(* Corrected by editor - changed from β to d.)