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.

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.

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.

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.

Negative Parity Levels in 30Si

1974 ◽  
Vol 52 (16) ◽  
pp. 1485-1491 ◽  
Author(s):  
M. Wayne Greene ◽  
H. H. Grawe ◽  
J. A. Kuehner
Keyword(s):  
Gamma Ray ◽  
Negative Parity ◽  
Coincidence Measurement ◽  
Model Structure ◽  
Polarization Direction ◽  
Decay Branch ◽  
Mean Lifetime ◽  
Doppler Shift Attenuation ◽  
Γ Rays ◽  
The Mean

A polarization direction correlation measurement of γ rays from the 7.044 MeV level in 30Si results in Jπ = 5− for this level and implies a Jπ = 4− assignment for the level at 6.503 MeV. A particle gamma ray coincidence measurement establishes a new decay branch (15 ± 4%) for the 6.503 MeV level to the 5.485 MeV Jπ = 3− level. The Doppler shift attenuation method was used to measure the mean lifetime of the 7.044 MeV level as [Formula: see text]. A simple shell model structure for the low lying negative parity states is presented and shown to be consistent with experimental measurements.

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.

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.

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.

Properties of the 4.038 MeV state in 25Al

1968 ◽  
Vol 46 (24) ◽  
pp. 2789-2796 ◽  
Author(s):  
H. Röpke ◽  
N. Anyas-Weiss ◽  
A. E. Litherland
Keyword(s):  
Decay Scheme ◽  
Previous Measurement ◽  
Proton Scattering ◽  
Parity Assignment ◽  
Attenuation Measurement ◽  
Mixing Ratios ◽  
Doppler Shift Attenuation ◽  
Inelastic Proton Scattering ◽  
Γ Rays ◽  
Γ Ray

The 4.038 MeV state in 25Al, which is also the Ep = 1.824 MeV resonance in the 24Mg(p,γ) reaction, has been investigated using the 24Mg(p,y) reaction. The γ-ray decay scheme is given and a limit of [Formula: see text], is obtained for the inelastic proton scattering width. Angular distribution measurements of deexcitation γ rays confirm previous values of radiation mixing ratios, but cannot remove the Jπ = 9/2+, 5/2+ ambiguity in the spin–parity assignment. A Doppler shift attenuation measurement of the4.038 MeV deexcitation γ ray yields ƒ(τ) = 0.91 ± 0.02, corresponding to a lifetime of τ(4.038) = 22 ± 6 fs. The particle widths are derived using the lifetime and a previous measurement of the γ-ray yield at the 24Mg, Ep = 1.824 MeV resonance. On the basis of the particle width, arguments are given for a Jπ = 9/2+ assignment to the 4.038 MeV state.

Sign in / Sign up

Export Citation Format

Share Document