NSSDCA ID: 1969-046E-02
Mission Name: Vela 5BThis experiment was designed to monitor the solar ambient and flare-produced flux of X rays in the 0.3- to 60-A wavelength region. Two identical X-ray sensor units were mounted at diametrically opposed apex positions on the satellite. Each unit contained four detectors: three ion chambers and a thallium-activated sodium iodide (NaI[Tl]) scintillation detector. As each ion chamber had a hemispherical window, the combined output signals from identical chambers in each sensor unit approximated the response of an ideal detector with a 4-pi-sr field of view. The ion chambers had the following window materials, gas fills, and wavelength responses. Chamber 1: 0.127 mm of beryllium, 0.9 atm of argon plus 0.1 atm of helium, 1 to 8 A. Chamber 2: 6.35 micrometers of mylar overcoated with about an 8500-A layer of aluminum, 0.5 atm of nitrogen, 1 to 16 A. Chamber 3: 6.35 micrometers of mylar, 0.5 atm of nitrogen, 1 to 16 A and 44 to 60 A. This combination of ion chambers allowed solar X-ray flux measurements in the bands 1 to 8 A, 1 to 16 A, 8 to 16 A, and 44 to 60 A to be obtained upon suitable analysis of the data. The scintillation detector used for the 0.3- to 3-A wavelength region consisted of a NaI(Tl) crystal optically coupled to a PMT, the output of which fed a five-level, integral, pulse-height analyzer. Unlike the ion chambers, the two scintillation detectors in the two sensor units were not identical. The more sensitive detector had a one-half-inch(1.27 cm)-diameter, 1-mm-thick crystal covered by a flat 10-mil(0.254 mm)-thick beryllium window. The less sensitive detector (1E-2 ergs/sq cm-s) had a one-quarter-inch(6.35 mm)-diameter, 1-mm-thick crystal and a 0.08-inch(2.032 mm)-thick beryllium dome window in addition to the flat 10-mil(0.254 mm) window mounted on the face of the crystal. Both ion chambers and scintillation detectors were capable of observations with time resolutions of 2 s. The average detective efficiencies for the ion and scintillation detectors were of the order of 20% and 60%, respectively.
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Name | Role | Original Affiliation | |
---|---|---|---|
Dr. Jack C. Fuller | Other Investigator | Los Alamos National Laboratory | |
Dr. Walter E. Kunz | Other Investigator | Los Alamos National Laboratory | |
Dr. W. H. Chambers | Principal Investigator | Los Alamos National Laboratory |