An atlas of 10-50 keV solar flare X-rays observed by the OGO satellites, 1 Jan. - 31 Dec. 1967
Summary of solar X ray events recorded by ionization chambers on OGO-A and OGO-B satellites during 1967
Kane, S. R.↗
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Nonuniformity of solar protons over the polar caps on March 24, 1966.
Solar protons nonuniformity over polar caps observed by OGO 2 ionization chamber during 24 March 1966 solar proton events
Anderson, H. R.↗
The altitude dependence of the quiettime cosmic ray ionization over the polar regions at solar minimum
Quiettime cosmic ray ionization altitude dependence over polar regions from measurements by integrating ionization chamber on OGO-2
George, M. J.↗
New data on the absolute cosmic ray ionization in the lower atmosphere
Absolute cosmic ray ionization in lower atmosphere, using air-filled ionization chamber
George, M. J.↗
A gas density detector for use in space
Ionized gas density monitor as meteoroid detector, describing operation in ionization chamber, proportional counter and glow tube modes
Meshejian, W. K.↗
Electron bombardment ion engine Patent
Electric rocket engine with electron bombardment ionization chamber
Masek, T. D.↗
Liquid-filled proportional counter
Liquid Xe filled single wire proportional and multiple wire ionization chambers, measuring gain and time/spatial resolution properties
Alvarez, L. W.↗
Methods and approaches to dosimetry
The development of a dosimetric system capable of determining energy depositions in tissue regions that are smaller than a few 100 nanometers is projected. These objectives are met by evaluation of the data produced by a macro-subsystem and a micro-subsystem. Both systems are in essence multiple ionization chambers that are normally operated in a gated pulse mode. The macro-system yields absorbed radiation dose as a function of location in a phantom of the human trunk when it operates in the dose mode; it registers only those sections as a signal in which the primary particle or any of its secondaries have passed, in the pulse mode. The function of the micro-system is to provide detailed information of the track structure by determining lateral energy spread due to delta ray formation or other secondary particle production.
Rossi, H. H.↗
Dose and linear energy transfer spectral measurements for the supersonic transport program
The purpose of the package, called the high altitude radiation instrumentation system (HARIS), is to measure the radiation hazard to supersonic transport passengers from solar and galactic cosmic rays. The HARIS includes gaseous linear energy transfer spectrometer, a tissue equivalent ionization chamber, and a geiger meuller tube. The HARIS is flown on RB-57F aircraft at 60,000 feet. Data from the HARIS are reduced to give rad and rem dose rates measured by the package during the flights. Results presented include ambient data obtained on background flights, altitude comparison data, and solar flare data.
Philbrick, R. B.↗
Experimental active and passive dosimetry systems for the NASA Skylab program
Active and passive dosimetry instrumentation to measure absorbed dose, charged particle spectra, and linear energy transfer spectra inside the command module and orbital workshop on the Skylab program were developed and tested. The active dosimetry system consists of one integral unit employing both a tissue equivalent ionization chamber and silicon solid state detectors. The instrument measures dose rates from 0.2 millirad/hour to 25 rads/hour, linear energy transfer spectra from 2.8 to 42.4 Kev/micron, and the proton and alpha particle energy spectra from 0.5 to 75 Mev. The active dosimeter is equipped with a portable radiation sensor for use in astronaut on-body and spacecraft shielding surveys during passage of the Skylab through significant space radiations. Data are transmitted in real time or are recorded by onboard spacecraft tape recorder for rapid evaluation of the radiation levels. The passive dosimetry systems consist of twelve (12) hard-mounted assemblies, each containing a variety of passive radiation sensors which are recoverable at the end of the mission for analysis.
Schneider, M. F.↗
Calibration of radiation detectors in the ultraviolet region between 972 and 2500 A
The development of experimental setups and procedures is considered for calibrating photosensitive devices in the spectral range 1022 to 2500 A for which no direct calibration techniques exist. An indirect technique that uses a sodium salicylate detector calibrated outside this range was developed for use as a secondary standard. The primary standard was a xenon-filled ionization chamber, which is an absolute standard over the wavelength interval 972 to 1022 A. Measurements made by this method were checked at 1470 A with a xenon lamp and at 2537 A with a mercury arc lamp and a 0.5 m blaze monochromator with a grating blazed at 2000 A. The overall accuracy of the measurements was + or - 40 percent or better.
Mcclenahan, J. O.↗
A liquid xenon radioisotope camera.
A new type of gamma-ray camera is discussed that makes use of electron avalanches in liquid xenon and is currently under development. It is shown that such a radioisotope camera promises many advantages over any other existing gamma-ray cameras. Spatial resolution better than 1 mm and counting rates higher than one million C/sec are possible. An energy resolution of 11% FWHM has recently been achieved with a collimated Hg-203 source using a parallel-plate ionization chamber containing a Frisch grid.
Zaklad, H.↗
Calculation of energy deposition distributions for simple geometries
When high-energy charged particles pass through a thin detector, the ionization energy loss in that detector is subject to fluctuations or straggling which must be considered in interpreting the data. Under many conditions, which depend upon the charge and energy of the incident particle and the detector geometry, the ionization energy lost by the particle is significantly different from the energy deposited in the detector. This problem divides naturally into a calculation of the energy loss that results in excitation and low-energy secondary electrons which do not travel far from their production points, and a calculation of energy loss that results in high-energy secondary electrons which can escape from the detector. The first calculation is performed using a modification of the Vavilov energy loss distribution. A cutoff energy is introduced above which all electrons are ignored and energy transferred to low energy particles is assumed to be equivalent to the energy deposited by them. For the second calculation, the trajectory of the primary particle is considered as a source of secondary high-energy electrons. The electrons from this source are transported using Monte Carlo techniques and multiple scattering theory, and the energy deposited by them in the detector is calculated. The results of the two calculations are then combined to predict the energy deposition distribution. The results of these calculations are used to predict the charge resolution of parallel-plate pulse ionization chambers that are being designed to measure the charge spectrum of heavy nuclei in the galactic cosmic-ray flux.
Watts, J. W., Jr.↗
Isotopic composition of heavy cosmic rays
The mean isotopic composition was measured of even-charge cosmic ray elements with 14 equal to or less than 26 near 0.8 GeV/N using a balloon-borne ionization-chamber/Cerenkov-counter detector system. The experimental method makes use of the geomagnetic field as a magnetic spectrometer. Results indicate that the most abundant isotopes at the cosmic ray source are Si-28, S-32, and Ca-40, like the solar system; but Fe-54, unlike the solar system.
Maehl, R. C.↗
Absolute photon-flux measurements in the vacuum ultraviolet
Absolute photon-flux measurements in the vacuum ultraviolet have extended to short wavelengths by use of rare-gas ionization chambers. The technique involves the measurement of the ion current as a function of the gas pressure in the ion chamber. The true value of the ion current, and hence the absolute photon flux, is obtained by extrapolating the ion current to zero gas pressure. Examples are given at 162 and 266 A. The short-wavelength limit is determined only by the sensitivity of the current-measuring apparatus and by present knowledge of the photoionization processes that occur in the rate gases.
Samson, J. A. R.↗
Mean isotopic composition of cosmic rays with 12 less than Z less than or equal to 26 at 2.7 to 3.0 GV
Results are presented from a high-altitude balloon flight in September 1972 near 3-GV geomagnetic cutoff. The detector is a combination of ionization chambers and a Lucite Cerenkov counter with a charge resolution of 0.34 charge units. Following the technique described by Lund et al. (1971), use is made of the geomagnetic rigidity cutoff and measured momentum-per-nucleon spectra of individual elements to determine values of A/Z for even Z elements of 16 less than or equal to Z less than or equal to 26 relative to A/Z of silicon.
Maehl, R. C.↗
Energy spectra of individual cosmic-ray elements with 12 less than or equal to Z less than or equal to 28
Results are presented from a high-altitude balloon flight in September 1972 of a detector using ionization chambers and a Lucite Cerenkov counter. Relative abundances of elements of 14 less than or equal to Z less than or equal to 30 are presented, as are energy spectra for individual elements between 0.8 and 1.6 GeV/N. A difference between the low- and high-energy relative abundances of iron and iron-secondaries is found, as well as a sharp fall-off in the Fe/Si ratio below 1 GeV/N.
Israel, M. H.↗
Ames collaborative study of cosmic ray neutrons
The results of a collaborative study to define both the neutron flux and the spectrum more precisely and to develop a dosimetry package that can be flown quickly to altitude for solar flare events are described. Instrumentation and analysis techniques were used which were developed to measure accelerator-produced radiation. The instruments were flown in the Ames Research Center high altitude aircraft. Neutron instrumentation consisted of Bonner spheres with both active and passive detector elements, threshold detectors of both prompt-counter and activation-element types, a liquid scintillation spectrometer based on pulse-shape discrimination, and a moderated BF3 counter neutron monitor. In addition, charged particles were measured with a Reuter-Stokes ionization chamber system and dose equivalent with another instrument. Preliminary results from the first series of flights at 12.5 km (41,000 ft) are presented, including estimates of total neutron flux intensity and spectral shape and of the variation of intensity with altitude and geomagnetic latitude.
Hewitt, J. E.↗