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Bertsch, D. L.

Publications and source records attributed to Bertsch, D. L..

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Characteristics of the telescope for high energy gamma-ray astronomy selected for definition studies on the Gamma Ray Observatory

The high energy gamma-ray telescope selected for definition studies on the Gamma Ray Observatory provides a substantial improvement in observational capability over earlier instruments. It will have about 20 times more sensitivity, cover a much broader energy range, have considerably better energy resolution and provide a significantly improved angular resolution. The design and performance are described.

Hughes, E. B.↗
NASA NTRS1979

Characteristics of the Telescope for High Energy Gamma-ray Astronomy Selected for Definition Studies on the Gamma Ray Observatory

The high energy gamma-ray selected for definition studies on the Gamma Ray Observatory provides a substantial improvement in observational capability over earlier instruments. It will have about 20 times more sensitivity, cover a much broader energy range, have considerably better energy resolution and provide a significantly improved angular resolution. The design and performance are described.

Hughes, E. B.↗
NASA NTRS1978

Observations of medium-energy gamma-ray emission from the galactic center region

Measurements of the gamma-ray emission in the medium-energy range between 15 and 100 MeV, obtained during two balloon flights from Brazil, are presented. The importance of this energy region in determining whether neutral-pion decay or electron bremsstrahlung is the most likely dominant source mechanism is discussed, along with the implications of such observations. Specifically, the data from this experiment suggest that emission from the galactic plane is similar to the theoretical spectrum calculated by Fichtel et al. (1976), including both source mechanisms but with the bremsstrahlung component enhanced by a factor of about 2. A spectral distribution of gamma-rays produced in the residual atmosphere above the instrument is also presented and compared with other data. A rather smooth spectral variation from high to low energies is found for the atmospheric spectrum.

Kniffen, D. A.↗
NASA NTRS1978

Observations of medium energy gamma ray emission from the galactic center region

Measurements of the gamma-ray emission in the medium energy range between 15 and 100 MeV, obtained during two ballon flights from Brazil are presented. The importance of this energy region in determining whether pi deg - decay of electron bremsstrahlung is the most likely dominant source mechanism is discussed along with the implications of such observations. Specifically, the data from this experiment suggest that emission from the galactic plane is similar to theoretical spectrum calculations including both sources mechanisms, but with the bremsstrahlung component enhanced by a factor of about 2. A spectral distribution of gamma-rays produced in the residual atmosphere above the instrument is also presented and compared with other data. A rather smooth spectral variation from high to low energies is found for the atmospheric spectrum.

Kniffen, D. A.↗
NASA NTRS1978

Energy spectrum of medium energy gamma-rays from the galactic center region

A balloon-borne magnetic core digitized spark chamber with two assemblies of spark-chambers above and below the scintillation counters was used to measure the medium energy gamma ray flux from the galactic center region. Gamma ray calculations are based on the multiple scattering of the pair electrons in 15 aluminum plates interleaved in the spark chamber modules. Counting rates determined during ascent and at ceiling indicate the presence of diffuse component in this energy range. Preliminary results give an integral flux between 15 and 70 MeV compared to the differential points in other results.

Palmeira, R. A. R.↗
NASA NTRS1977

Enhancement of solar heavy nuclei at high energies in the 4 July 1974 event

Relative abundances of energetic nuclei in the July 4, 1974, solar event are presented. The results show a marked enhancement of abundances that systematically increase with nuclear charge numbers in the range of the observation (Z between 6 and 26) for energies above 15 MeV/nucl. While such enhancements are commonly seen below 10 MeV/nucl, most observations at higher energies are found to be consistent with solar-system abundances. The energy spectrum of oxygen is observed to be significantly steeper than most other solar events studied in this energy region. It is proposed that these observations are characteristic of particle populations at energies of the order of 1 MeV/nucl and that the anomalous features observed may be the result of the high-energy extension of such a population that is commonly masked by other processes or populations that might occur in larger solar events.

Bertsch, D. L.↗
NASA NTRS1977

Gamma-ray astronomy in the medium energy (10-50 MeV) range

To observe the medium energy component of the intense galactic center gamma-ray emission, two balloon flights of a medium energy gamma-ray spark chamber telescope were flown in Brazil in 1975. The results indicate the emission is higher than previously thought and above the predictions of a theoretical model proposed.

Kniffen, D. A.↗
NASA NTRS1976

Enhancement of solar heavy nuclei at high energies in the 4 July 1974 event

Relative abundances of energetic nuclei in the 4 July 1974 solar event are presented. The results show a marked enhancement of abundances that systematically increase with nuclear charge numbers in the range of the observation, 6 less than or equal to Z less than or equal to 26 for energies above 15 MeV/nucleon. While such enhancements are commonly seen below 10 MeV/nucleon, most observations at higher energies are found to be consistent with solar system abundances. The energy spectrum of oxygen is observed to be significantly steeper than most other solar events studied in this energy region. It is proposed that these observations are characteristic of particle populations at energies approximately 1 MeV/nucleon, and that the anomalous features observed here may be the result of the high energy extension of such a population that is commonly masked by other processes or populations that might occur in larger solar events.

Bertsch, D. L.↗
NASA NTRS1974

Solar cosmic ray composition above 10 MeV/nucleon and its energy dependence in the 4 August 1972 event

Observations of the proton, helium (C,N,O) and Fe-group nuclei fluxes made during the large 4 August 1972 solar particle event are presented. The results show a small, but significant variation of the composition of multicharged nuclei as a function of energy in the energy region above 10 MeV/nucleon. In particular, the He/(C,N,O) abundance ratio varies by a factor approximately 2 between 10 and 50 MeV/nucleon, and the Fe-group/(C,N,O) ratio suggests a similar variation. Abundance ratios from the 4 August 1972 event are compared as a function of energy with ratios measured in other solar events. At energies approximately greater than 50 MeV/nucleon, the He/(C,N,O) abundance ratio for August 1972 is consistent with all earlier measurements made above that energy.

Bertsch, D. L.↗
NASA NTRS1974

Variations in the nuclear abundances in solar particle events

Measurements of the flux of helium nuclei in the 24 January 1971 event and of helium and (C, N, O) nuclei in the 1 September 1971 event are combined with previous measurements to obtain the relative abundances of helium, (C, N, O), and Fe-group nuclei in these events. These data are then summarized together with previously reported results to show that, even when the same detector system using a dE/dx plus range technique is used, differences in the He/(C, N, O) value in the same energy/nucleon interval are observed in solar cosmic ray events. Further, when the He/(C, N, O) value is lower the He/(Fe-group nuclei) value is also systematically lower in these large events.

Bertsch, D. L.↗
NASA NTRS1973

Variations of the relative abundances of He, (C,N,O) and Fe-group nuclei in solar cosmic rays and their relationship to solar particle acceleration

Measurements of the flux of helium nuclei in the 24 January 1971 event and of helium and (C,N,O) nuclei in the 1 September 1971 event are combined with previous measurements to obtain the relative abundances of helium, (C,N,O), and Fe-group nuclei in these events. These data are then summarized together with previously reported results to show that, even when the same detector system using a dE/dx plus range technique is used, differences in the He/(C,N,O) value in the same energy/nucleon interval are observed in solar cosmic ray events. Further, when the He/(C,N,O) value is lower the He/(Fe-group nuclei) value is also systematically lower in these large events. When solar particle acceleration theory is analyzed, it is seen that the results suggest that, for large events, Coulomb energy loss probably does not play a major role in determining solar particle composition at higher energies (10 MeV). The variations in multicharged nuclei composition are more likely due to partial ionization during the acceleration phase.

Bertsch, D. L.↗
NASA NTRS1972

Measurements of the Fe-group abundance in energetic solar particles

The abundance of Fe-group nuclei in the energetic solar particles was measured twice in the 24 January 1971 event and once in the 2 September 1971 event. Including earlier results from the 2 September 1966 event, the Fe-group abundance was found to be in the range from 3% to 6% of the oxygen nuclei in the energy interval from 21 to 50 MeV/nucleon, in those events where the Fe-group abundance could be measured. Fe-nuclei have a different charge-to-mass ratio from that of the C, N, O nuclei, so small variations in the Fe abundance in solar particles are expected. In the three exposures where the statistics were adequate to construct an energy spectrum, the Fe-group nuclei were seen to have an energy/nucleon spectrum similar to that of the C, N, O nuclei; however, the energy/nucleon range was limited. The abundance for the Fe-group nuclei is consistent with the present solar spectroscopic abundance estimates.

Bertsch, D. L.↗
NASA NTRS1972

Supernovae studied with a ground level atmospheric fluorescence

A monitoring experiment was undertaken late 1968 to search for photon bursts of extraterrestrial origin. The experiment and the results of the observations to date are summarized. The method of detection employs ground-based photomultiplier tubes which are sensitive to the secondary fluorescence light that would be produced when the primary pulse is absorbed in the atmosphere.

Bertsch, D. L.↗
NASA NTRS1972

Nuclear composition and energy spectra in the 1969 April 12 solar-particle event.

Measurement of the charge composition for several of the multicharged nuclei and the energy spectra for hydrogen, helium, and medium (6 less than or equal to Z less than or equal to 9) nuclei in the Apr. 12, 1969, solar-particle event. The energy/nucleon spectral shape of the medium nuclei was again the same as that of the helium nuclei, and the ratio of these two species was consistent with the present best average of 58 plus or minus 5. By combining the results obtained here with previous work, improved estimates of the Ne/O and Mg/O values of 0.16 plus or minus 0.03 and 0.056 plus or minus 0.014, respectively, were obtained. Silicon and sulfur abundances relative to O were determined to be 0.208 plus or minus 0.008 plus or minus 0.006, respectively, and 85% confidence upper limits for Ar and Ca relative to O of 0.017 and 0.010 were obtained. Previously, these last four nuclei had only been listed as a group.

Bertsch, D. L.↗