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.

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.

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.

Nuclear alinement of manganese-56

1959 ◽  
Vol 250 (1263) ◽  
pp. 550-561 ◽  
Keyword(s):  
Angular Distribution ◽  
Excited State ◽  
Angular Correlation ◽  
Excited States ◽  
Daughter Nucleus ◽  
Γ Radiation ◽  
Mixing Ratios ◽  
First Excited State ◽  
Γ Rays ◽  
Coincidence Measurements

The present work demonstrates the feasibility of alining manganese-56 produced by neutron irradiation of a nickel fluosilicate crystal containing stable 55 Mn. Measurements were made of the angular distribution of the γ-radiation from the alined 56 Mn and also of the angular correlation of the γ-rays from this isotope. By combining the results it is possible to establish uniquely as 2 the spins of the states of the daughter nucleus of 56 Fe at 2.66 and 2.98 MeV. The mixing ratios δ ( E 2/ M 1) for the 1.81 and 2.13 MeV γ-rays to the first excited state are shown to be 0.19 ± 0.02 and — 0.28 ± 0.02. The spectrum of the γ-radiation was studied with a scintillation spectrometer and this leads to the following relative intensities; 0.845 MeV (100%), 1.81 MeV (27 ± 3%), 2.13 MeV (15 ± 3%), 2.55 MeV (1.2 ± 0.2%), 2.66 MeV (0.65 ± 0.1%), 2.98 MeV (0.35 ± 0.1%) and 3.4 MeV (0.22 ± 0.05%). Coincidence measurements suggest that the 2.55 and 3.4 MeV γ-rays are due to de-excitation of a level at about 3.4 MeV which decays both to the ground and first excited states. A spin of 2 for this state is proposed.

Gamma-Ray Linear Polarization and Angular Distribution Formulas in Terms of Phase-Defined Reduced Matrix Elements

1971 ◽  
Vol 49 (3) ◽  
pp. 328-351 ◽  
Author(s):  
P. Taras
Keyword(s):  
Angular Distribution ◽  
Linear Polarization ◽  
Gamma Ray ◽  
Polarization Measurement ◽  
Recent Measurement ◽  
Full Potential ◽  
Matrix Elements ◽  
Mixing Ratios ◽  
Nuclear Models

Gamma-ray linear polarization and angular distribution formulas are presented in terms of the phase-defined reduced matrix elements of Rose and Brink. In particular, the mixing ratios are phase consistently related to reduced matrix elements of interaction multipole operators which are also well defined in phase. The mixing ratios extracted from the measurements of gamma-ray angular distribution and linear polarization can then be compared in both magnitude and sign with the predictions of nuclear models. The full potential of a gamma-ray linear polarization measurement is demonstrated by the discussion of a recent measurement.

Positive-Parity Bands in 29Si

1971 ◽  
Vol 49 (10) ◽  
pp. 1263-1274 ◽  
Author(s):  
A. A. Pilt ◽  
R. H. Spear ◽  
R. V. Elliott ◽  
J. A. Kuehner
Keyword(s):  
Angular Distribution ◽  
Excited State ◽  
Linear Polarization ◽  
Ground State ◽  
Gamma Ray ◽  
Positive Parity ◽  
Rotational Bands ◽  
Mixing Ratios ◽  
First Excited State ◽  
Nilsson Model

A study has been made of several high spin members of the ground state (Kπ = 1/2+) and first-excited state (Kπ = 3/2+) rotational bands in the presumed oblate nucleus 29Si. Gamma-ray angular distribution and linear polarization measurements have confirmed the spin and parity of the 4081 keV level to be 7/2+, and levels at 4742 and 5283 keV have been shown to have Jπ = 9/2+ and (7/2+, 3/2+) respectively. Branching and mixing ratios for the transitions from these states have also been determined; in conjunction with previously measured lifetimes, transition strengths are calculated. The results are compared with the predictions of a Nilsson-model calculation including the effects of coriolis mixing of the low-lying positive parity bands.

scholarly journals Monte Carlo Simulation of γ − γ Correlation Functions

Atoms ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 6
Author(s):  
Mohamed Omer ◽  
Mahmoud Bakr
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Angular Distribution ◽  
Correlation Functions ◽  
Energy State ◽  
Nuclear Resonance ◽  
Resonance Fluorescence ◽  
Spin Parity ◽  
Nuclear Resonance Fluorescence ◽  
Γ Rays

γ − γ correlation functions are mathematical expressions that describe the angular distribution of cascade γ -rays emitted from an atomic nucleus. Cascade transitions may occur in either a two-step deexcitation or through an excitation-deexcitation process of a particular energy level inside the nucleus. In both cases, the nucleus returns to its ground energy state. Spin and parity of the excited state can be determined experimentally using the asymmetry of the angular distribution of the emitted radiation. γ − γ correlation functions are only valid for point-like targets and detectors. In the real experiments, however, neither the target nor the detector is point-like. Thus, misassignment of the spin-parity of energy levels may easily take place if only the analytical equations are considered. Here, we develop a new Monte Carlo simulation method of the γ − γ correlation functions to account for the extended target and detector involved in spin-parity measurements using nuclear resonance fluorescence of nuclei. The proposed simulation tool can handle arbitrary geometries and spin sequences. Additionally, we provide numerical calculations of a parametric study on the influence of the detection geometry on the angular distribution of the emitted γ -rays. Finally, we benchmark our simulation by comparing the simulation-estimated asymmetry ratios with those measured experimentally. The present simulation can be employed as a kernel of an implementation that simulates the nuclear resonance fluorescence process.

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 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 Measurement of the angular distribution of γ-rays emitted from the compound state after neutron capture by 81Br for a search of T-violation

2019 ◽  
Vol 219 ◽  
pp. 09003 ◽  
Author(s):  
Shunsuke Endo ◽  
Hirohiko M. Shimizu ◽  
Masaaki Kitaguchi ◽  
Hirota Katsuya ◽  
Tomoki Yamamoto ◽  
...  
Keyword(s):  
Angular Distribution ◽  
Parity Violation ◽  
Neutron Capture ◽  
P Waves ◽  
Compound State ◽  
T Violation ◽  
Reversal Invariance ◽  
Candidate Target ◽  
First Results ◽  
Γ Rays

It is known that parity violation can be enhanced in compound nuclei due to mixing of s- and p-waves, and it is suggested that time reversal invariance (T) violation is enhanced by the same mechanism. We are planing a T-violation search using compound nuclei produced in neutron capture reactions. Although 81Br is one of the candidate target nuclei, its sensitivity to T-violation has not yet been determined. For an estimate of the latter, a measurement of the angular distribution of γ-rays emitted in the 81Br(n,γ) reaction was carried out in November 2017, of which we report first results.

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