Measurements of Solar Extreme Ultraviolet and X-Rays from Rockets by Means of a CoSO4:Mn Phosphor

Abstract

The presence of solar extreme ultraviolet and x-rays at high altitudes in the atmosphere was detected by means of a thermoluminescent phosphor, CaS${\mathrm{O}}_4$:Mn, which was not sensitive to wavelengths above 1340A. Samples of the phosphor were flown in V-2 rockets and exposed to sunlight. By means of filters of Be, LiF, and Ca${\mathrm{F}}_2$, response was measured in the wavelength bands 0-8A, 1050-1340A, and 1230-1340A. X-rays were observed on one flight which reached 128 km, during which a sudden ionospheric disturbance occurred. Wavelengths between 1050 and 1340A were observed on all four flights and reached as low as 80-90 km. A tentative value of 0.04 microwatt/${\mathrm{cm}}^2$ was calculated for the total intensity in the solar spectrum in the range 1050-1240A, which includes the Lyman alpha-line of hydrogen, at an altitude level somewhere between 82 and 127 km. A similar value for the range 1230-1340A was 0.02 microwatt/${\mathrm{cm}}^2$. A comparison of the responses of the phosphor strips flown without filters and those with filters indicated that radiation between 795 and 1050A reaches the region 82-127 km with an intensity well above that produced by a 6000°K blackbody sun.