NEUTRON CAPTURE γ-RAYS FROM HEAVY EVEN-CHARGE NUCLEI

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

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.

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
Keyword(s):  
Energy Range ◽  
Gamma Rays ◽  
Ground State ◽  
Neutron Capture ◽  
State Transition ◽  
High Energy ◽  
The Other ◽  
Ground State Transition ◽  
Γ Rays ◽  
Γ Ray

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.

NEUTRON CAPTURE γ-RAYS FROM HEAVY ODD-CHARGE NUCLEI

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

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.

scholarly journals Molecular Clouds Observed by the EGRET Gamma-Ray Telescope

1997 ◽  
Vol 170 ◽  
pp. 22-24 ◽  
Author(s):  
Seth. W. Digel ◽  
Stanley D. Hunter ◽  
Reshmi Mukherjee ◽  
Eugéne J. de Geus ◽  
Isabelle A. Grenier ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Molecular Clouds ◽  
Gamma Ray ◽  
Angular Resolution ◽  
Cosmic Ray ◽  
High Energy ◽  
Background Rejection ◽  
Γ Rays ◽  
Γ Ray ◽  
Production Mechanisms

EGRET, the high-energy γ-ray telescope on the Compton Gamma-Ray Observatory, has the sensitivity, angular resolution, and background rejection necessary to study diffuse γ-ray emission from the interstellar medium (ISM). High-energy γ rays produced in cosmic-ray (CR) interactions in the ISM can be used to determine the CR density and calibrate the CO line as a tracer of molecular mass. Dominant production mechanisms for γ rays of energies ∼30 MeV–30 GeV are the decay of pions produced in collisions of CR protons with ambient matter and Bremsstrahlung scattering of CR electrons.

scholarly journals Review of observational results on γ-ray background: (Invited discourse)

1970 ◽  
Vol 37 ◽  
pp. 269-279 ◽  
Author(s):  
G. W. Clark ◽  
G. P. Garmire ◽  
W. L. Kraushaar
Keyword(s):  
Power Law ◽  
Strong Evidence ◽  
Galactic Plane ◽  
High Energy ◽  
Electromagnetic Spectrum ◽  
Γ Rays ◽  
Γ Ray ◽  
Region 10

Recent observations in the X- and γ-Ray region of the electromagnetic spectrum have given strong evidence for the existence of an extragalactic intensity with a slowly steepening power law spectrum in the region 103 to 108 eV. Further data from the OSO-III high energy γ-Ray detector are in agreement with earlier published reports, and suggest that the γ-Rays from high galactic latitudes have a softer spectrum than those from the galactic plane.

scholarly journals A Possible Discovery of a Flaring 1012 eV Gamma-Ray Source near the Red Dwarf EV Lac

1995 ◽  
Vol 151 ◽  
pp. 78-79
Author(s):  
I.Yu. Alekseev ◽  
N.N. Chalenko ◽  
V.P. Fomin ◽  
R.E. Gershberg ◽  
O.R. Kalekin ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Electronic Device ◽  
Angular Size ◽  
High Energy ◽  
Optical Systems ◽  
Relativistic Electrons ◽  
Large Area ◽  
Γ Rays ◽  
Γ Ray ◽  
Ev Lac

During the 1994 coordinated observations of the red dwarf flare star EV Lac, the star was monitored in the very high energy (VHE) γ-ray range around 1012 eV with the Crimean ground-based γ-ray telescope GT-48. This telescope consists of two identical optical systems (Vladimirsky et al. 1994) which were directed in parallel on EV Lac.The detection principle of the VHE γ-rays is based on the Čerenkov radiation emitted by relativistic electrons and positrons. The latter are generated in the interaction of the γ-rays with nuclei in the Earth’s atmosphere that leads to an appearance of a shower of charged particles and γ-quanta. The duration of the Cherenkov radiation flash is very short, just about a few nanoseconds. The angular size of the shower is ∼ 1°. To detect such flashes we use an optical system with large area mirrors and a set of 37 photomultipliers (PMs) in the focal plane. Using the information from these PMs which are spaced hexagonally and correspond to a field of view of 2°.6 on the sky, we can obtain the image of an optical flash. The electronic device permits us to detect nanosecond flashes (40 ns exposure time and 12 μs readout dead-time).

Gamma rays and high-energy neutrons in the atmosphere

1968 ◽  
Vol 46 (10) ◽  
pp. S1030-S1033 ◽  
Author(s):  
M. V. K. Apparao ◽  
R. R. Daniel ◽  
George Joseph ◽  
G. S. Gokhale ◽  
P. J. Lavakare ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Counting Rate ◽  
Plastic Scintillator ◽  
Pulse Height ◽  
Growth Curves ◽  
High Energy ◽  
Cutoff Rigidity ◽  
Energy Formula ◽  
Γ Rays ◽  
Γ Ray

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.

scholarly journals Particle Acceleration in Extragalactic Jets and Implications for the High-Energy Emission from Blazars

1994 ◽  
Vol 159 ◽  
pp. 29-32
Author(s):  
R. Schlickeiser ◽  
C. D. Dermer
Keyword(s):  
Compton Scattering ◽  
Accretion Disk ◽  
High Energy ◽  
Relativistic Electrons ◽  
Spectral Evolution ◽  
Inverse Compton Scattering ◽  
Central Engine ◽  
Inverse Compton ◽  
Γ Rays ◽  
Γ Ray

We demonstrate that the prevalence of superluminal sources in the sample of γ-ray blazars and the peak of their luminosity spectra at γ-ray energies can be readily explained if the γ-rays result from the inverse Compton scattering of the accretion disk radiation by relativistic electrons in outflowing plasam jets. Compton scattering of external radiation by nonthermal particles in blazar jets is dominated by accretion disk photons rather than scattered radiation to distances of ∼ 0.01–0.1 pc from the central engine for standard parameters. The size of the γ-ray photosphere and the spectral evolution of the relativistic electron spectra constrain the location of the acceleration and emission sites in these objects.

scholarly journals Massive stars at (very) high energies: γ-ray binaries

2010 ◽  
Vol 6 (S272) ◽  
pp. 581-586
Author(s):  
Guillaume Dubus ◽  
Benoît Cerutti
Keyword(s):  
High Energy Physics ◽  
Thermal Emission ◽  
Compact Object ◽  
High Energy ◽  
Be Stars ◽  
Radiative Power ◽  
Very High Energy ◽  
Γ Rays ◽  
Γ Ray ◽  
Very High

Abstractγ-ray binaries are systems that emit most of their radiative power above 1 MeV. They are associated with O or Be stars in orbit with a compact object, possibly a young pulsar. Much like colliding wind binaries, the pulsar generates a relativistic wind that interacts with the stellar wind. The result is non-thermal emission from radio to very high energy γ-rays. The wind, radiation and magnetic field of the massive star play a major role in the dynamics and radiative output of the system. They are particularly important to understand the high energy physics at work. Inversely, γ-ray binaries offer novel probes of stellar winds and insights into the fate of O/B binaries.

THE NEUTRON CAPTURE 7-RAYS FROM POTASSIUM

1953 ◽  
Vol 31 (6) ◽  
pp. 927-931 ◽  
Author(s):  
G. A. Bartholomew ◽  
B. B. Kinsey
Keyword(s):  
Excited State ◽  
Potassium Carbonate ◽  
Ground State ◽  
Neutron Capture ◽  
State Transition ◽  
Ground State Transition ◽  
Γ Rays ◽  
Γ Ray

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.

Thermal neutron capture γ-ray spectrum of molybdenum and ruthenium

1991 ◽  
Vol 69 (6) ◽  
pp. 658-664 ◽  
Author(s):  
M. A. Islam ◽  
T. J. Kennett ◽  
W. V. Prestwich
Keyword(s):  
Thermal Neutron ◽  
Neutron Capture ◽  
Nuclear Reactor ◽  
Thermal Neutron Capture ◽  
Global Average ◽  
Transition Level ◽  
Γ Rays ◽  
Γ Ray ◽  
Strength Functions ◽  
Mcmaster University

The thermal neutron capture γ rays from natural molybdenum and ruthenium have been studied using a pair spectrometer and the tangential facility at the McMaster University Nuclear Reactor. Precise transition, level, and neutron separation energies of different isotopes are inferred. The separation energies are: Sn(93Mo) = 8069.76 ± 0.09, Sn(95Mo) = 7369.10 ± 0.10, Sn(96Mo) = 9154.31 ± 0.05, Sn(97Mo) = 6821.15 ± 0.25, Sn(98Mo) = 8642.55 ± 0.07, Sn(99Mo) = 5925.42 ± 0.15, Sn(100Ru) = 9673.48 ± 0.05, and Sn(102Ru) = 9219.64 ± 0.05 keV. The M1 strength functions of 100Ru,102Ru, 96Mo, and 98Mo are (34 ± 15) × 10−9, (82 ± 41) × 10−9, (22 ± 7) × 10−9, and (25 ± 8) × 10−9 MeV−3, respectively. All values but that for 102Ru agree with the global average of (20 ± 6) × 10−9 MeV−3. The average [Formula: see text] of 96Mo observed is 247 ± 175 e2 fm4 MeV−1.

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