Hard X-ray spectrum of a plasma focus
Plasma focus hard X ray spectrum, using electron sensitive nuclear emulsions
Lee, J. H.↗
SEARCH · Search NASA
Results for “NUCLEAR EMULSION”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Solar particle composition measurements
The composition of solar particle events, that is the relative abundance of different elements, was studied, using nuclear emulsion detectors flown on board sounding rockets. These observations were extended to elements as heavy as iron. A model is discussed in which the particles in a flare are stripped of electrons in the high temperature of a flare region, and subsequently are accelerated presumably by magnetic fields.
Reames, D. V.↗
Iridium and tantalum foils for spaceflight neutron dosimetry.
Description of a two-foil system of iridium and tantalum which can measure thermal and intermediate energy neutrons at flux densities of 1 neutron/sq cm-sec over a ten-day lunar mission (1,000,000 neutrons/sq cm). The foils are chemically inert and nontoxic, weigh less than 1 g each, and require only routine gamma pulse height analysis for activation measurement. Detection of fluences below 1,000,000 neutrons/sq cm are achieved for counts of foil activity made as late as two months following neutron exposure. Tantalum foils flown in Apollo 11 indicated a mean dose equivalent to the astronauts of less than 16 mrem from thermal plus intermediate energy neutrons, while nuclear emulsion track analysis indicated approximately 17 mrem from neutrons of energy greater than 0.6 MeV. Iridium foils flown on Apollo 12 indicated dose equivalents of 1.8 to 2.8 mrem from thermal neutrons, excluding tissue thermalized SNAP-27 neutrons.
English, R. A.↗
Gamma-ray emission from the region of the Galactic center.
A combination nuclear-emulsion-spark-chamber gamma-ray telescope has been used to study the region of sky that includes the Galactic center. Ninety-five per cent confidence upper limits on the flux from the reported sources G-gamma 2+3 and Sgr gamma-1 were placed at .000044 and .000088 photons per sq cm per sec, and a similar limit on the emission from the Galactic center as a point source was placed at .000033 photons per sq cm per sec. No enhanced emission was observed from the Galactic plane. Three regions of enhanced emission were observed that had a combined Poisson probability of occurrence of less than .005. One of these is associated with a region of enhanced emission reported by other workers.
Dahlbacka, G. H.↗
Observation of cosmic-ray particles with Z of 50 or greater and interpretation of the charge spectrum.
Large areas of plastic detectors and nuclear emulsions were exposed to the primary cosmic radiation on two high-altitude balloon flights in May 1968 and September 1969. From measurements on the tracks found in the scanning of the plastic detectors, events with charges Z greater than 50 were selected, and these data were consolidated with those from our earlier flights. Several conclusions can be drawn from the observed charge spectrum. The detection of trans-bismuth nuclei confirms earlier observations of these particles in the cosmic rays. However, no trans-uranium particles were observed. Detailed features of the charge spectrum cannot be explained by nuclei from r-process nucleosynthesis alone. Although the addition of particles following s-process abundances yields improved agreement, the spectrum appears more complicated than would result from a simple combination of r- and s-process abundances with identical propagation histories.
Blanford, G. E., Jr.↗
Primary cosmic ray particles with z 35 (VVH particles)
Large areas of nuclear emulsions and plastic detectors were exposed to the primary cosmic radiation during high altitude balloon flights. From the analysis of 141 particle tracks recorded during a total exposure of 1.3 x 10 to the 7th power sq m ster.sec., a charge spectrum of the VVH particles has been derived.
Blanford, G. E., Jr.↗
Primary cosmic ray particles with Z greater than 35 /VVH particles/
Large areas of nuclear emulsions and plastic detectors were exposed to the primary cosmic radiation during high-altitude balloon flights. From an analysis of 141 particle tracks recorded during a total exposure of 13,000,000 sq m-ster-sec, a charge spectrum of the VVH particles has been derived.
Blanford, G. E., Jr.↗
Cosmic ray experimental observations
The current experimental situation in cosmic ray studies is discussed, with special emphasis on the development of new detector systems. Topics covered are the techniques for particle identification, energy measurements, gas Cerenkov counters, magnet spectrometers, ionization spectrometers, track detectors, nuclear emulsions, multiparameter analysis using arrays of detectors, the Goddard ionization spectrometer, charge spectra, relative abundances, isotope composition, antinuclei in cosmic rays, electrons, the measurement of cosmic ray arrival directions, and the prehistory of cosmic rays.
Balasubrahmanyan, V. K.↗
Measurement of proton spectra on satellites from the Cosmos series of artificial satellites
In 1966-1967 measurements were performed at altitudes from 200 to 400 km to determine the fluxes and spectra of protons by means of nuclear emulsions of the BR-2 and Ya-2 types. The proton spectra within the range up to 8 BeV are presented. The spectra obtained are the basis for estimating radiation hazards.
Kovalev, Y. Y.↗
Measurement of spectra and neutron fluxes on artificial earth satellites from the Cosmos series
In 1966-1967 measurements were carried out at the altitudes of 200 to 400 km to determine the spectra and fluxes of fast neutrons inside the hermetically sealed artificial earth satellites of the Cosmos series. The detectors used were nuclear emulsions of the B9 and BR types and an emulsion of the P9 type, filled with Li and P. Spectra and fluxes of neutrons in the range of energies from thermal energies to 10 MeV are presented. Neutron doses are also estimated.
Dudkin, V. Y.↗
Microdosimetric structure of HZE particle tracks in tissue
Heavy nuclei of the primary galactic radiation in space can have the same linear energy transfer yet greatly different lateral distribution patterns of the energy in the microstructure of tissue. Track structure thus presents itself as a new dosimetric parameter for HZE particles which is at present incompletely understood in its radiobiological significance. The theory of track structure distinguishes two regions: core and penumbra. The core is a narrow region with a radius far below 1 micron in tissue where energy deposition occurs mainly through excitations and collective oscillations of electrons. Energy density in the core accounts for slightly more than half the total LET. The penumbra surrounding the core extends laterally several to many microns depending on the energy of the primary. Energy density in the penumbra decreases steeply with the square of increasing radius. The relationships are illustrated with nuclear emulsion micrographs and plots of energy density profiles. The implications of the findings for a dosimetric system for HZE particles are discussed.
Schaefer, H. J.↗
Status of the evidence for a magnetic monopole
The experimental evidence supporting the detection of a moving magnetic monopole, using a balloon-borne array of track detectors, was presented. Although the results cannot be proved to have been produced by a monopole, they do not seem to have been produced by any nucleus. The very high, roughly constant ionization rate inferred from track etch rate measurements in a stack of Lexan detectors implies passage of a minimum-ionizing particle more highly charged than any known nucleus, yet the Cerenkov film detectors indicated a velocity less than about 0.68 times the speed of light and the size of the track in the nuclear emulsion indicated a velocity approximately equal to 0.5 times the speed of light. At this velocity the ionization rate of a highly electrically charged particle would have changed dramatically with pathlength unless its mass to charge ratio were far greater than that of a nucleus.
Price, P. B.↗
Detection of the isotopes of heavy cosmic ray nuclei
A counter telescope designed to detect and resolve the isotopic composition of cosmic ray nuclei heavier than neon is being prepared. The telescope consists of a rather conventional charge measuring array using two scintillator elements and two solid Cerenkov radiators of differing refractive index. The mass measurement is obtained by combining the velocity information from one or both of the Cerenkov radiators operating near their threshold with residual range measured in a block of nuclear emulsion. Path length corrections and particle location in the emulsions is provided by a spark chamber fired in coincidence with potentially suitable particles. The telescope has a geometry factor of 530 sq cm sr roughly. It should be able to resolve the isotopes of iron over the energy range of 300 to 720 Mev/n and those of neon over 300 to 400 MeV/n. The expected response and characteristics of the telescope are described in detail and the sensitivity to rare isotopes discussed.
Gilman, C. M.↗
Correlation of individual cosmic ray nuclei with the observation of light flashes by Apollo astronauts
A nuclear emulsion detector known as the Apollo Light Flash Moving Emulsion Detector (ALFMED) was designed: (1) to record tracks of primary cosmic rays; (2) to provide time-of-passage information via a relative plate translation technique; (3) to provide particle trajectory information; and (4) to fit into a masklike device that could be located about the head and eyes of an astronaut. An ALFMED device was worn by an astronaut observing light flashes for 60 minutes on each of the last two Apollo missions. During the Apollo 17 experiment seventeen separate flashes were reported by the observer. With one-third of the total plate area completely analyzed, two definite correlations have been found between Z greater than 8 cosmic ray nuclei traversing an eye and the reports of visual sensations.
Pinsky, L. S.↗
Some isotopic abundances in the cosmic radiation
Cosmic ray nuclei with Z not less than 10 have been observed in a detector which measures charge with a double scintillator-Cherenkov array and mass by combining the Cherenkov signal with residual range measured in nuclear emulsions. Results are presented for the isotopic analyses of Al, Ca, Sc, Mn, Fe, Co, Ni and Cu in the energy range 300-800 MeV/amu.
Young, J. S.↗
Confirmation of the anomalous behavior of energetic nuclear fragments
Cosmic-ray nuclei have been observed to produce 2072 secondary fragments in nuclear interactions detected in nuclear emulsions. These fragments produce 557 further interactions. Previous reports that these secondary nuclei show anomalously short mean free paths near their point of origin are confirmed. This effect can be interpreted as being due to all fragments having cross sections about twice normal for some 10 to the -10 sec after creation, or to a small fraction having cross sections an order of magnitude greater than normal.
Barber, H. B.↗
The characteristics of particles emitted in energetic nucleus-nucleus interactions
The analysis of the interactions of heavy cosmic ray nuclei in nuclear emulsion exposed over Texas is continued, with 500 interactions of nuclei of E greater than 1.5 GeV/nucleon added. In this paper the experimental data correlating meson production with fragmentation of the projectile and target nuclei are given. These data, combined with earlier results, are also used to reexamine the problem of the mean free path of secondary fragments. Using the same techniques of analysis used for the accelerator ions, evidence is found for anomalously short mean free paths of secondary fragments in the first centimeter after production.
Barber, H. B.↗
Abundance of low energy (50-150 MeV) antiprotons in cosmic rays
The progress is presented of the nuclear emulsion experiment to determine abundance of low energy antiprotons in cosmic rays. No antiprotons have been detected so far at upper limit of p/p less than or similar to 4 x .0001 in the energy range 50 MeV to 15 MeV.
Apparao, K. M. V.↗