C. D. Swift

Ta181(p, n)W181 and Au197(p, n)Hg197 excitation functions between 4 and 13 MeV

Excitation functions for the Ta/sup 181/(p,n)W/sup 181/ and Au/sup 197/ (p,n)Hg/sup 197/ reactions were measured for incident proton energies from 4 to 13 Mev. The stacked foil method was used. The activity of the foils was measured by counting the gamma rays and X-rays emitted when the product nuclei decay by electron capture. Absolute values of the cross sections were measured at several energies for these reactions and were compared with the cross sections for compound nucleus formation given by Shapiro. Threshold energies for the (p,2n) reactions were obtained by comparing the present data with neutron yields obtained from long counter measurements. The (p,2n) thresholds are 7.5 Mev for Ta/sup 181/ and 8.3 Mev for Au/sup 197/. The absolute (p,2n) cross section values were also obtained. The total reaction cross sections above 7 Mev are compared with optical model calculations. Results confirm the assumption of a surface absorption potential. (auth)

SCORPIUS XR-1: SOME X-RAY AND OPTICAL OBSERVATIONS (1969 MAY).

Simultaneous X ray and optical observations of Scorpius XR-1, comparing rocket data from various flights

OBSERVATION OF SEVERAL X-RAY SOURCES IN 1970 SEPTEMBER.

Position and intensity measurements made with proportional counters in the 2 to 12 keV band are described. The instruments were launched from Johnson Atoll, and four scans were carried out during the 525 sec spent above 200 km. In comparing the results with the Uhuru survey, only a few differences are noted. One variable source, 2U 1908+0, was weaker. The case of the Magellanic Cloud sources is discussed.

Proportional Counters and Electronic Systems for Observing Cosmic X Rays

A low‐energy x‐ray detection system has been developed and used on two sounding rocket flights. Proportional counters, sensitive to x rays with quantum energies between 2 and 30 keV, are used in this system. The signals from these counters are modified so that they can be telemetered with an FM‐FM system in such a way that the pulse amplitude is preserved. Pulse‐height analysis is done at the ground station. With this simple system, it is possible to obtain spectra of cosmic x‐ray sources limited only by the resolution of the detectors.