Radioactivity produced in Discoverer XVII by November 12, 1960, solar protons

Scintillation-spectroscopy measurements on a AgBr emulsion block from Discoverer XVII, which was flown during a period of high solar cosmic-ray activity on November 12, 1960, reveal a gamma-ray spectrum attributable to 8.4-day Ag106. The disintegration rate, corrected to a probable production time of 2200 UT, November 12, 1960, is 14 dis sec−1. If one assumes a (p, pn) cross section of 100 mb, and applies the thin-target formula for production of radioactivity, this corresponds to a total proton dosage of about 1.6×108 protons cm−2 within the emulsion, and to a value of 16 rads radiation dosage. An attempt to measure the gamma spectrum of 40-day Ag105 was unsuccessful, allowing the assignment of an upper limit on the disintegration rate of 1 dis sec−1 at the time of production. A search for 1.3-year Cd109 has been unsuccessful.