NEUTRON CAPTURE GAMMA RAYS FROM FLUORINE, MAGNESIUM, GALLIUM, BROMINE, AND HAFNIUM

1957 ◽  
Vol 35 (12) ◽  
pp. 1361-1379 ◽  
Author(s):  
P. J. Campion ◽  
G. A. Bartholomew

The neutron capture γ-ray spectra of fluorine, magnesium, gallium, bromine, and hafnium have been studied in the energy range above 3 Mev. In fluorine four γ-rays and in magnesium 12 γ-rays have been detected in addition to those previously observed. Most of these new radiations can be assigned to the known level schemes of the product nuclei. The spectrum obtained for each of the other elements is complex with only a few of the high energy γ-rays resolved, and in each case the γ-ray of highest energy is very weak and difficult to distinguish from the background. The most energetic gallium γ-ray at 7.73 ± 0.02 Mev. may be emitted in the direct ground state transition in Ga70 while the 7.879 ± 0.013 Mev. γ-ray from bromine probably corresponds to the ground state transition in Br80. In hafnium none of the observed γ-rays can be identified with a ground state transition in any of the isotopes.

1953 ◽  
Vol 31 (6) ◽  
pp. 927-931 ◽  
Author(s):  
G. A. Bartholomew ◽  
B. B. Kinsey

The capture γ-rays from potassium have been re-examined with greater resolution than was used in previous experiments. The upper end of the spectrum has been carefully studied both with a sample of natural potassium carbonate and with another in which the potassium was enriched in K40. From a comparison of the spectra two γ-rays with energies of 9.39 ± 0.06 and 8.45 ± 0.02 Mev. are assigned to capture by that isotope. The strong γ-ray at 7.757 ± 0.008 Mev. previously ascribed to the ground state transition in K40 is now found to represent a transition to a low-lying excited state in that nucleus.


1968 ◽  
Vol 46 (10) ◽  
pp. S1030-S1033 ◽  
Author(s):  
M. V. K. Apparao ◽  
R. R. Daniel ◽  
George Joseph ◽  
G. S. Gokhale ◽  
P. J. Lavakare ◽  
...  

In continuation of our earlier experiments studying the emission of solar neutrons, we have now developed detector systems which respond to γ rays of energy 1–5 MeV and neutrons of energy [Formula: see text]. The two detectors are almost identical. Each consists of a CsI (Na) crystal (B) of diameter 3.8 cm, completely enclosed in a tapered cylinder of plastic scintillator (A) operated in anticoincidence; the crystals have thicknesses of 2.4 and 1.2 cm respectively. A balloon carrying these detectors was flown on March 16, 1967 over Hyderabad, India (vertical cutoff rigidity 16.9 GV) and floated at a ceiling altitude of 6.0 mb for 1 hour. In addition to γ-ray and neutron events (AB), events A and AB were also continuously monitored throughout the flight. Pulses corresponding to 1–5 MeV in the 2.4-cm crystal (γ rays) and 6–40 MeV in the 1.2-cm crystal (high-energy neutrons) were analyzed by a 64-channel pulse-height analyzer. On the basis of the pulse-height distributions and γ-ray efficiencies in the two crystals, we attribute events of 1–5 MeV energy from the thicker crystal to γ rays and those > 10 MeV in energy from the thinner one to stars produced by high-energy neutrons [Formula: see text] in the crystal. Atmospheric growth curves for γ rays and neutrons have been obtained; these growth curves as well as those for events A and AB show the normal features of the Pfotzer maximum, steady decreases up to the ceiling altitude, and a constant counting rate at ceiling. The atmospheric counting rates at ceiling altitude give for γ rays of energy 1–5 MeV a flux of ~1 photon per cm2 s and for neutrons of energy [Formula: see text] a flux of ~0.1 neutron per cm2 s. No evidence for a solar component in either channel was found.


1968 ◽  
Vol 46 (10) ◽  
pp. S700-S705 ◽  
Author(s):  
A. V. Apanasenko ◽  
L. T. Baradzei ◽  
E. A. Kanevskaya ◽  
V. V. Rykov ◽  
Yu. A. Smorodin ◽  
...  

The problem of the existence of a change of slope in the γ-ray spectrum in the atmosphere is of considerable interest in connection with conclusions about the change in the character of the nucleon interaction. Up to now this problem has not been solved experimentally. In this report the γ-ray spectrum in the 1011–1013 eV energy range has been obtained using data from X-ray films and nuclear emulsions exposed on board an airplane at a pressure of 200 g/cm2. The total exposure was 425 hours∙m2. The energies of the electron–photon cascades initiated by γ rays were determined in the X-ray films by measuring the photometric densities of the black spots, and in nuclear emulsions by counting the electron tracks near the cascade axis. The integral spectrum has a power-law form with an exponent of 1.7–1.9. A change in slope in the spectrum was not found. Thus, a mechanism generating pions with energies proportional to the initial nucleon energies exists up to nucleon energies of ~1014 eV. The analysis of the accompaniment of γ rays by "families" shows that in one-third of the cases the energy of the most energetic π0 meson is at least five times that of the next π0 meson. In the remaining two-thirds of the cases the π0 mesons have comparable energies.


2008 ◽  
Vol 17 (10) ◽  
pp. 1849-1858 ◽  
Author(s):  
J. M. PAREDES

The detection of TeV gamma-rays from LS 5039 and the binary pulsar PSR B1259–63 by HESS, and from LS I +61 303 and the stellar-mass black hole Cygnus X-1 by MAGIC, provides clear evidence of very efficient acceleration of particles to multi-TeV energies in X-ray binaries. These observations demonstrate the richness of nonthermal phenomena in compact galactic objects containing relativistic outflows or winds produced near black holes and neutron stars. I review here some of the main observational results on very high energy (VHE) γ-ray emission from X-ray binaries, as well as some of the proposed scenarios to explain the production of VHE γ-rays. I put special emphasis on the flare TeV emission, suggesting that the flaring activity might be a common phenomena in X-ray binaries.


1984 ◽  
Vol 62 (10) ◽  
pp. 948-962 ◽  
Author(s):  
W. V. Prestwich ◽  
T. J. Kennett ◽  
J. S. Tsai

A high-resolution study of the γ-ray spectrum induced by the inelastic scattering of reactor produced neutrons has been conducted. The γ rays observed have been assigned in a decay scheme involving 134 levels extending in excitation energy to 6 MeV. The results are discussed within the context of previously identified weak coupling configurations, and possible discrepancies are indicated. Levels in the high-energy region are also compared with recently reported photoexcitation studies.


1953 ◽  
Vol 31 (7) ◽  
pp. 1025-1050 ◽  
Author(s):  
G. A. Bartholomew ◽  
B. B. Kinsey
Keyword(s):  
Γ Rays ◽  

The neutron capture γ-ray spectra of arsenic, niobium, rhodium, silver, indium, antimony, praseodymium, tantalum, gold, and thallium are described. The energies and intensities of the strongest high energy γ-rays are given for each element.


1953 ◽  
Vol 31 (7) ◽  
pp. 1051-1086 ◽  
Author(s):  
B. B. Kinsey ◽  
G. A. Bartholomew
Keyword(s):  
Γ Rays ◽  

The neutron capture γ-ray spectra of the elements selenium, strontium, zirconium, molybdenum, cadmium, tin, barium, samarium, gadolinium, wolfram, platinum, and mercury are described. The energies and intensities of the strongest high energy γ-rays are given for each element.


1966 ◽  
Vol 44 (5) ◽  
pp. 1087-1097 ◽  
Author(s):  
R. J. A. Levesque ◽  
R. W. Ollerhead ◽  
E. W. Blackmore ◽  
J. A. Kuehner

Levels at 6.69, 6.88, and 6.89 MeV were observed in the 16O(16O, α)28Si reaction, and angular correlations were measured for the resulting gamma-ray transitions, using the geometry in which the alpha particle is detected at 0°. The level at 6.69 MeV had not been reported previously and was assigned spin and parity 0+. The doublet of levels at 6.88–6.89 MeV was not resolved in these measurements, but angular correlations of the gamma-ray transitions were possible, using spectrum subtraction techniques. One member of the doublet, previously assigned spin 3, has a strong ground-state transition; the angular correlation for this transition confirms a 3− assignment to this level. The other member of the doublet, which decays almost entirely to the first excited state, could not be assigned a spin on the basis of these measurements. However, taken in conjunction with other measurements, an assignment of 4+ is favored.


1975 ◽  
Vol 53 (4) ◽  
pp. 351-359 ◽  
Author(s):  
W. V. Prestwich ◽  
A. M. Lopez

Capture gamma-ray spectra for the reaction 59Co(n, γ)60Co were obtained for different neutron energy distributions. Significant contributions from the high energy resonances were observed. Analysis of the data for the ground state transition indicates that the contribution to the process from potential direct capture is substantially smaller than previous estimates. No retardation of transitions to final states exhibiting an ln = 3 (d,p) stripping pattern, such as that observed for 132 eV capture, is evident for the higher energy resonances.


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