Etude d'une transition possible à trois multipoles dans la désintégration gamma du niveau à 1612 keV de l'37Ar

1976 ◽  
Vol 54 (10) ◽  
pp. 997-999 ◽  
Author(s):  
R. Vaillancourt ◽  
P. Taras
Keyword(s):  
Angular Distribution ◽  
Linear Polarization ◽  
Simultaneous Measurement ◽  
Beam Axis ◽  
Γ Rays ◽  
Γ Ray

The γ-ray decay of the 1612 keV level (τ = 6.38 ± 0.15 ns) in 37Ar has been analyzed in terms of a mixture of three multipoles. The data was obtained from the simultaneous measurement of the linear polarization and angular distribution of the decay γ rays, in coincidence with the neutrons emitted along the beam axis, the level being populated via the 34S(α, n)37Ar reaction at Eα = 10.5 MeV. The results definitively eliminate the possibility of the γ rays consisting of a mixture of three multipoles, thereby confirming the Jπ = 7/2− assignment to the level.

Propriétés des niveaux de l'37Ar entre 2.7 et 3.8 MeV d'énergie d'excitation

1975 ◽  
Vol 53 (22) ◽  
pp. 2534-2543 ◽  
Author(s):  
R. Vaillancourt ◽  
B. Haas ◽  
P. Taras
Keyword(s):  
Angular Distribution ◽  
Excitation Energy ◽  
Linear Polarization ◽  
Simultaneous Measurement ◽  
Beam Axis ◽  
Spin Parity ◽  
Mixing Ratios ◽  
Γ Rays

The properties of seven levels in 37Ar were studied via the 34S(α,n)37Ar reaction at Eα = 10.5 MeV. The simultaneous measurement of the linear polarization and the angular distribution of the decay γ rays, in coincidence with the neutrons emitted along the beam axis, provided values of the branching and mixing ratios of these γ rays. From these measurements the spin–parity values for the following levels were established, excitation energy in keV: Ex(Jπ) = 2797(5/2+), 3170(5/2+), 3185(9/2−), 3274(5/2−), 3527(7/2−), 3605(3/2+), 3706(7/2−). The Jπ values of the 3706 keV level are in disagreement with the results of Gadeken et al.

Band Structure in 21Ne

1972 ◽  
Vol 50 (12) ◽  
pp. 1286-1294 ◽  
Author(s):  
A. A. Pilt ◽  
R. H. Spear ◽  
R. V. Elliott ◽  
D. T. Kelly ◽  
J. A. Kuehner ◽  
...  
Keyword(s):  
Angular Distribution ◽  
Band Structure ◽  
Linear Polarization ◽  
Negative Parity ◽  
Mixing Ratios ◽  
Decay Branch ◽  
Nilsson Model ◽  
Γ Rays ◽  
Model Evidence ◽  
Γ Ray

The 18O(α,nγ) reaction at α-particle bombarding energies of 5.2 and 6.1 MeV was used to study the levels in 21Ne below 4 MeV excitation. A combination of γ-ray angular distribution and linear polarization measurements using a single crystal Ge(Li) polarimeter confirmed the spins and parities of the 1747 and 2867 keV states to be 7/2+ and 9/2+ respectively and assigned negative parity to the J = 3/2 level at 3663 keV and J = 5/2 level at 3886 keV. The state at 3735 keV was shown to have Jπ = 5/2+. Values of the multipole mixing ratios of γ rays deexciting these states were found to be consistent with previous measurements. A γ–γ coincidence experiment revealed the existence of a (1.8 ± 0.7)% decay branch of the 3886 keV level to the 2790 keV level. The results are interpreted in terms of the Nilsson model. Evidence for the existence of a Kπ = 1/2− band based on a hole in the 1p1/2 shell is given.

Study of the 1459-keV level in 19F by the 19F(p,p′γ)19F reaction

1970 ◽  
Vol 48 (7) ◽  
pp. 827-833 ◽  
Author(s):  
S. T. Lam ◽  
A. E. Litherland ◽  
J. J. Simpson
Keyword(s):  
Angular Distribution ◽  
Single Crystal ◽  
Linear Polarization ◽  
Proton Energy ◽  
Branching Ratios ◽  
Mixing Ratio ◽  
Γ Ray ◽  
Good Agreement

The 1459-keV level of 19F was populated by the 19F(p,p′γ)19F reaction at a proton energy of 2.78 MeV. The E2/M1 mixing ratio for the 1459 → 110 keV transition was determined to be [Formula: see text] from a combination of the γ-ray angular distribution and linear polarization and the nuclear lifetime. The γ-ray angular distribution was measured with a coaxial Ge(Li) detector and the γ-ray linear polarization with a planar Ge(Li) detector. The corresponding E2 and M1 transition strengths for a lifetime of 0.084 ± 0.020 ps are found to be [Formula: see text] and 0.10 ± 0.03 W.u. respectively. They are in good agreement with the particle–hole calculations of Benson and Flowers. The branching ratios of the 1459-keV level agree well with those of Poletti et al. The γ-ray transitions from the 1459-keV level provide a good example for demonstrating the usefulness of a single crystal Ge(Li) polarimeter.

THE ANGULAR DISTRIBUTION OF γ-RAYS FROM Mn54 ORIENTED IN ANTIFERROMAGNETIC CoCl2.6H2O

1962 ◽  
Vol 40 (10) ◽  
pp. 1332-1341 ◽  
Author(s):  
J. M. Daniels ◽  
D. J. Griffiths
Keyword(s):  
Angular Distribution ◽  
Polar Axis ◽  
Obtuse Angle ◽  
Satisfactory Explanation ◽  
Antiferromagnetic Materials ◽  
Nuclear Alignment ◽  
Antiferromagnetic Ground State ◽  
Γ Rays ◽  
Γ Ray ◽  
State Configuration

The angular distribution of γ-rays from Mn54 nuclei, included as an impurity in antiferromagnetic CoCl2.6H2O, was measured at temperatures between 0.03 °K and 0.18 °K. Three γ-ray counters were placed, one each along the crystallographic a, b, and c axes, and the angular distribution was analyzed into a series of spherical harmonics. The aspheric component of the γ-ray distribution was found to be proportional to [Formula: see text], where θ and [Formula: see text], are polar co-ordinates; the polar axis is the crystallographic b axis, and the origin of [Formula: see text] is 46° from the a axis in the obtuse angle between the a and c axes. This result is discussed in terms of present knowledge of the antiferromagnetic ground state configuration of CoCl.6H2O and of present ideas of the mechanism of nuclear alignment in antiferromagnetic materials, but no satisfactory explanation is found.

Angular distribution of the 3H(p,γ)4He reaction at proton energies below 1 MeV

1980 ◽  
Vol 58 (10) ◽  
pp. 1496-1499 ◽  
Author(s):  
W. Del Bianco ◽  
G. Kajrys
Keyword(s):  
Angular Distribution ◽  
Differential Cross Section ◽  
Cross Section ◽  
Differential Cross ◽  
Angular Range ◽  
Γ Rays ◽  
Γ Ray ◽  
Energy Dependent

The differential cross section of the 3H(p,γ)4He reaction has been measured at the proton energies Ep = 0.46, 0.50, 0.62, 0.77, and 0.93 MeV. A thin 3H–Ti target has been used and the γ-rays have been detected by a 12.7 cm diameter × 15.2 cm long NaI(Tl) crystal rotating over the angular range θL = 0 to 135°. The 3H(p,γ)4He reaction is found to proceed through E1, M1, and E2 transitions, E1 transitions being predominant. The ratio of the γ-ray flux at θL = 0 and 90° is energy dependent and decreases from 0.017 ± 0.003 at Ep = 0.46 MeV to 0.0078 ± 0.006 at Ep = 0.93 MeV.

CAPTURE RADIATION AND NEUTRONS FROM THE BOMBARDMENT OF C14 WITH PROTONS

1955 ◽  
Vol 33 (8) ◽  
pp. 441-456 ◽  
Author(s):  
G. A. Bartholomew ◽  
F. Brown ◽  
H. E. Gove ◽  
A. E. Litherland ◽  
E. B. Paul
Keyword(s):  
Angular Distribution ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Total Yield ◽  
Isotopic Spin ◽  
Proton Bombardment ◽  
Neighboring State ◽  
Γ Rays ◽  
Γ Ray

The yield and angular distribution of ground state γ-rays and of neutrons resulting from the proton bombardment of C14 have been studied for proton energies from 0.2 to 2.5 Mev. Assignments of spin and parity are made to most of the resonances observed in this range. A single particle proton state which may have isotopic spin 3/2 has been observed. The interference of this state, which has spin 1/2+, with a neighboring state of the same spin and parity is observed in the total yield of the ground state γ-ray. Three states below the neutron threshold which have been observed previously in the N14(d, p)N15 reaction are also observed in the C14(p, γ)N15 reaction. The N14(n, p)C14 cross section at thermal energies can be accounted for by a resonance observed in this experiment, but another resonance below the neutron threshold must be assumed to account for the thermal (n, n) and (n, γ) cross sections.

The high spin states in 147Tb excited by the (6Li,3n) reaction

1980 ◽  
Vol 58 (11) ◽  
pp. 1617-1624 ◽  
Author(s):  
Tasneem A. Khan ◽  
M. W. Johns
Keyword(s):  
Angular Distribution ◽  
High Spin ◽  
Linear Polarization ◽  
Level Scheme ◽  
Internal Conversion ◽  
Gamma Ray ◽  
Spin States ◽  
Excitation Functions ◽  
High Spin States ◽  
Γ Ray

High spin states in 147Tb have been excited by means of the 144Sm(6Li,3n) reaction and studied by means of γ-ray and electron measurements. Gamma-ray singles, excitation functions, angular distribution, linear polarization, γ–γ coincidence, and internal conversion measurements have been made. These have led to unambiguous spin and parity assignments to many levels and to lifetime determinations for two states. The resulting level scheme is discussed and compared with recent calculations.

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.

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