NUCLEAR ORIENTATION IN ANTIFERROMAGNETIC SINGLE CRYSTALS

1961 ◽  
Vol 39 (1) ◽  
pp. 53-64 ◽  
Author(s):  
J. M. Daniels ◽  
J. C. Giles ◽  
M. A. R. LeBlanc
Keyword(s):  
Single Crystals ◽  
Nuclear Orientation ◽  
Γ Rays ◽  
Γ Ray

Mn54 and Co60 have been successfully oriented in five antiferromagnetic single crystals (MnCl2∙4H2O, MnBr2∙4H2O, CoCl2∙6H2O, Co(NH4)2(SO4)2∙ 6H2O, and MnSiF6∙6H2O) and the orientation was detected by the anisotropy of the emitted γ rays. Only in the case of Co60 in MnBr2∙4H2O was no γ-ray anisotropy seen. It is concluded that antiferromagnetism can be used as a means of producing nuclear orientation. Attempts to orient Br82 and 1131 in the manganese halides by superexchange were unsuccessful.

A new design for a γ -ray Compton scattering spectrometer

1985 ◽  
Vol 398 (1815) ◽  
pp. 405-414 ◽  
Keyword(s):  
Single Crystals ◽  
Compton Scattering ◽  
Small Samples ◽  
Compton Profile ◽  
Accurate Data ◽  
Annular Geometry ◽  
Γ Rays ◽  
Γ Ray

A new design for a γ-ray Compton scattering spectrometer is presented. The spectrometer uses an annular geometry that is the inversion of the annular geometry used in earlier experiments with americium γ-rays. A small source is placed directly in front of the detector so that it is the detector and not the source that provides the annulus. Measurements of the Compton profile of aluminium are used to evaluate the new design. For small samples it is possible to increase the intensity by a factor of up to 10 4 while maintaining the resolution. This should make it possible to obtain accurate data for many compounds that could not previously be studied because of the difficulties associated with obtaining large single crystals.

THE LOW-TEMPERATURE ORDERED STATE OF CERIUM MAGNESIUM NITRATE AND ITS INFLUENCE ON NUCLEAR ORIENTATION

1964 ◽  
Vol 42 (8) ◽  
pp. 1469-1480 ◽  
Author(s):  
J. M. Daniels ◽  
J. Felsteiner
Keyword(s):  
Magnetic Field ◽  
Nuclear Orientation ◽  
Dipole Interaction ◽  
Magnesium Nitrate ◽  
Divalent Ions ◽  
Antiferromagnetic Ordering ◽  
Γ Rays ◽  
Γ Ray ◽  
The Magnetic Field ◽  
Ordered State

The method of Luttinger and Tisza for minimizing the dipole–dipole interaction energy is applied to cerium magnesium nitrate, and an antiferromagnetic ordering of the cerium spins at 0 °K is found. Using this configuration, the magnetic field at the divalent ions is calculated. Next, the anisotropy of γ rays from Co60 aligned in this salt is calculated for temperatures below 0.003 °K. Qualitative agreement is found between these calculations and measurements of γ-ray anisotropy reported in the literature.

THE EFFECT OF INTERACTIONS ON THE ANGULAR DISTRIBUTION OF γ-RAYS FROM AN ASSEMBLY OF ORIENTED NUCLEI

1957 ◽  
Vol 35 (9) ◽  
pp. 1133-1145 ◽  
Author(s):  
J. M. Daniels
Keyword(s):  
Angular Distribution ◽  
Energy State ◽  
Nuclear Orientation ◽  
Γ Radiation ◽  
Orientation Experiment ◽  
High Temperature Approximation ◽  
Γ Rays ◽  
Matrix Formula ◽  
Paramagnetic Ions ◽  
Radioactive Ions

The angular distribution of γ-radiation from an assembly of nuclei oriented by the magnetic h.f.s. method can be very much modified by interactions between the radioactive ions and other paramagnetic ions in the crystal. In order to calculate the effect of these interactions, an operator Γ is derived which represents the angular distribution of γ-rays from a radioactive nucleus. The angular distribution at any temperature is given by Spur(Γρ), where ρ is the statistical matrix [Formula: see text], [Formula: see text] being the Hamiltonian for the whole crystal. For a high temperature approximation, ρ is expanded in powers of 1/T. It is found that, for alignment by the magnetic h.f.s. method, the first term which contains interaction parameters is that in 1/T4, and an expression is given for the contribution of interactions to this term.At very low temperatures, perturbation theory is used to estimate the effect of interactions on the lowest nuclear energy state, and hence on the angular distribution of γ-rays. It is found that, if an external magnetic field is applied along a principal axis of the g-tensor of the radioactive ions, interactions have no influence on the angular distribution of γ-rays in the limit of large fields. It is also shown that Bleaney's restriction, that for a successful nuclear orientation experiment the broadening of the levels should be less than the hyperfine splitting, is not necessary in this case.

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 A γ-ray diffraction study of extinction in annealed silicon single crystals

1987 ◽  
Vol 43 (a1) ◽  
pp. C210-C210
Author(s):  
J. R. Schneider ◽  
O. Gonçalves ◽  
H. A. Graf ◽  
W. Zulehner
Keyword(s):  
Diffraction Study ◽  
Single Crystals ◽  
Γ Ray

scholarly journals High Spin States in 193Hg

2020 ◽  
Vol 4 ◽  
pp. 170
Author(s):  
N. Fotiades ◽  
Et al.
Keyword(s):  
Excited States ◽  
High Spin ◽  
Normal Level ◽  
Beam Energy ◽  
Spin Structure ◽  
Spin States ◽  
Tandem Accelerator ◽  
High Spin States ◽  
Γ Rays ◽  
Γ Ray

The high-spin structure of 193Hg was investigated by in-beam γ-ray spectro­scopic techniques. The tandem accelerator at Daresbury Laboratory, U. K., was used to populate excited states of 193Hg through the reaction 150Nd(48Ca,5n)193Hg at a beam energy of 213 MeV and the EUROGAM detector array was used to de­ tect the γ-rays emitted by the deexciting nuclei. The normal level scheme has been further extended and a new band has been observed. In addition two new ΔI=1 structures of competing dipole and quadrupole transitions were found which will be discussed in detail.

scholarly journals The Galactic population and properties of young, highly energetic pulsars

2020 ◽  
Vol 497 (2) ◽  
pp. 1957-1965
Author(s):  
Simon Johnston ◽  
D A Smith ◽  
A Karastergiou ◽  
M Kramer
Keyword(s):  
Radio Emission ◽  
Birth Rate ◽  
Selection Effect ◽  
Gap Model ◽  
Radio Pulsars ◽  
Galactic Population ◽  
Small Set ◽  
Γ Rays ◽  
Γ Ray ◽  
Partial Overlap

ABSTRACT The population of young, non-recycled pulsars with spin-down energies $\dot{E} \gt 10^{35}$ erg s−1 is sampled predominantly at γ-ray and radio wavelengths. A total of 137 such pulsars are known, with partial overlap between the sources detectable in radio and γ-rays. We use a very small set of assumptions in an attempt to test whether the observed pulsar sample can be explained by a single underlying population of neutron stars. For radio emission we assume a canonical conal beam with a fixed emission height of 300 km across all spin periods and a luminosity law which depends on $\dot{E}^{0.25}$. For γ-ray emission we assume the outer-gap model and a luminosity law which depends on $\dot{E}^{0.5}$. We synthesize a population of fast-spinning pulsars with a birth rate of one per 100 yr. We find that this simple model can reproduce most characteristics of the observed population with two caveats. The first is a deficit of γ-ray pulsars at the highest $\dot{E}$ which we surmise to be an observational selection effect due to the difficulties of finding γ-ray pulsars in the presence of glitches without prior knowledge from radio frequencies. The second is a deficit of radio pulsars with interpulse emission, which may be related to radio emission physics. We discuss the implications of these findings.

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 Intensive evaluation of radiation stability of phlogopite single crystals under high doses of γ-ray irradiation

RSC Advances ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 6199-6210 ◽  
Author(s):  
Honglong Wang ◽  
Yaping Sun ◽  
Jian Chu ◽  
Xu Wang ◽  
Ming Zhang
Keyword(s):  
Single Crystals ◽  
Radiation Stability ◽  
Lattice Plane ◽  
Radiolysis Products ◽  
Γ Ray ◽  
High Doses

Upon irradiation, the framework underwent breakage, H2O underwent radiolysis, and the radiolysis products reacted with the framework, expanding the lattice plane.

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