Engineering topics
Publications and source records attributed to Levine, A..
A soft X-ray survey (0.15-1.5 keV) of the Large Magellanic Cloud (LMC) during a sounding rocket flight, reveals possible emission from the centrally located barlike structure. No evidence was seen for absorption of the soft X-ray 'background' in the direction of the LMC. Both of these observations support the hypothesis of a local production of the soft X-ray background.
A recent sounding rocket experiment in which the X-ray variations of Cir X-1 and Vela X-1 were investigated at time resolutions down to 1 msecond is described. Sporadic flaring activity in the X-ray sources was observed on time scales from 1 to several seconds, corresponding to intensity changes of about 20% in Cir X-1 and up to 100% in Vela X-1. Periodic, aperiodic, or quasi-periodic pulsations were not detected with time constants less than 1 second. The limits of rapid X-ray pulsations are shown to range from 3 to 15% for Cir X-1, Cyg X-1, Vela X-1, and 3U 1700-37.
The celestial position of the binary X-ray source Her X-1 has been measured with a precision of 30 sec and, within the uncertainties, agrees with the position of the optical variable HZ Herculis. An average light curve for the 1.24-sec periodicity has been obtained with about 10-msec resolution. The average pulse is a double-peaked structure which shows significant intensity changes in time scales down to 30 msec.
A sealed Ti window proportional counter sensitive to X radiation in the energy range 0.35-0.45 keV and above 1.5 keV is described. Measurements of the Ti mass absorption coefficients and a graphical summary of the literature values are presented. For a proportional counter with a 930 microgram/sq cm (2.1-micron) Ti window, the peak efficiency at 0.45 keV is found to lie between 4.6% and 7.1%. An application in X-ray astronomy involving a rocket observation of Sco X-1 is discussed.