AN ILLUSTRATION OF A TYPE OF TRIPLE CORRELATION MEASUREMENT WHICH CAN BE EASILY INTERPRETED

1960 ◽  
Vol 38 (7) ◽  
pp. 927-940 ◽  
Author(s):  
A. E. Litherland ◽  
G. J. McCallum
Keyword(s):  
Angular Correlation ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Residual Nucleus ◽  
Incident Beam ◽  
Electric Quadrupole ◽  
Final States ◽  
Angular Correlations ◽  
Mixing Ratios ◽  
Triple Correlation

The Mg26(He4, nγ)Si29 reaction has been used to illustrate the simplifications introduced in the interpretation of triple angular correlations by choosing a target and bombarding particles of zero spin and by observing the emitted particles, in this case neutrons, in a counter fixed at 0° to the beam. The angular correlations of the gamma rays with respect to the incident beam then depend only upon the properties of the final states in the residual nucleus. The angular correlation of the electric quadrupole 2.03-Mev gamma ray is predicted uniquely by theory and this prediction has been verified experimentally. The angular correlations of the 1.28-Mev and 2.43-Mev gamma rays have yielded for the E2/M1 amplitude mixing ratios +0.25 ± 0.05 or −3.4 ± 0.5 and −0.26 ± 0.08 or −1.10 ± 0.16 respectively. In addition, the experiment provides an illustration of the value of the recently discovered technique of neutron – gamma-ray discrimination in an organic scintillator.

GAMMA-RAY ANGULAR CORRELATIONS FROM ALIGNED NUCLEI PRODUCED BY NUCLEAR REACTIONS

1961 ◽  
Vol 39 (6) ◽  
pp. 788-824 ◽  
Author(s):  
A. E. Litherland ◽  
A. J. Ferguson
Keyword(s):  
Angular Correlation ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Residual Nucleus ◽  
Incident Beam ◽  
Nuclear Spectroscopy ◽  
Population Parameters ◽  
Axially Symmetric ◽  
Angular Correlations

Two general procedures for the measurement and analysis of angular correlations of gamma radiations from nuclear reactions are described which have wide applications in nuclear spectroscopy for the determination of spins and gamma-ray multipolarities. Cases can be studied by these methods when the reaction proceeds through a compound state too complex to allow the usual analysis to be made, for example where several levels overlap or where direct interaction is dominant. The basis of these procedures is to exploit the simplifications brought about by making the reacting system axially symmetric. A sharp gamma-ray-emitting state formed in such a system can be regarded as aligned and described in terms of a relatively small number of population parameters for the magnetic substates. In the first procedure, a state Y* is prepared by a nuclear reaction X(h1h2) Y* in which h2 is unobserved. The state Y* has axial symmetry about the beam axis. From coincidence angular correlation measurements of two cascade gamma rays from Y*, the unknown population parameters for Y* together with the nuclear spins and gamma-ray multipolarities can be determined. In the second procedure, h2 is measured in a small counter at 0° or 180° relative to the incident beam. It is then shown that the quantum numbers of the magnetic substates of Y* which can be populated do not exceed the sum of the spins of X, h1, and h2. In cases where the sum of the spins does not exceed [Formula: see text], the angular correlation of the gamma rays from the aligned state depends only upon the properties of the states in the residual nucleus. Theoretical expressions for angular correlations from aligned states are given, together with a method whereby existing extensive tables of coefficients can be used to calculate them. The results of two recent experiments are discussed as examples.

Determination of mixing ratios for some cascades corresponding to 109Ag

1977 ◽  
Vol 55 (2) ◽  
pp. 175-179 ◽  
Author(s):  
H. E. Bosch ◽  
V. M. Silbergleit ◽  
M. Davidson ◽  
J. Davidson
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Angular Correlations ◽  
Mixing Ratios ◽  
Multichannel Analyzer ◽  
Level 3 ◽  
Gamma Ray Detector

An investigation of the gamma–gamma ray angular correlations following the decay of 109Pd was made by using a Ge(Li) semiconductor counter and NaI(Tl) gamma-ray detector. Coincidences measurements at six different angles were made between the 311 keV gamma ray (gated in the movable counter) and 390, 413, 424, 551, and 558 keV gamma rays (displayed in a multichannel analyzer (MCA)). Chance coincidences as well as coincidence background were taken into account. The following spins and mixing ratios were determined: 701 keV level 3/2, δ(390) = 0.19 ± 0.06; 724 keV level 3/2, δ(413) = 0.18 ± 0.05; 735 keV level 5/2, δ(424) = −0.27 ± 0.03; 862 keV level 5/2, δ(551) = −0.28 ± 0.04; 869 keV level 5/2, δ(558) = −0.26 ± 0.05. The result indicates that the anisotropies are consistent with mixing ratios less than 28% in all cases.

EXCITED STATES OF O18 STUDIED BY THE REACTION

1961 ◽  
Vol 39 (2) ◽  
pp. 276-294 ◽  
Author(s):  
A. E. Litherland ◽  
R. Batchelor ◽  
A. J. Ferguson ◽  
H. E. Gove
Keyword(s):  
Excited States ◽  
Gamma Rays ◽  
Recent Experiment ◽  
Gamma Ray ◽  
Electric Quadrupole ◽  
Angular Correlations ◽  
Small Admixture ◽  
First Excited State ◽  
Cascade Transition ◽  
Crossover Transition

Gamma rays from the excited states of O18 at 3.63 and 3.92 Mev have been observed using the reaction [Formula: see text] at an incident O16 energy of 14 Mev. Both states were observed to emit gamma rays to the 1.98-Mev 2+ first excited state of O18. No evidence for crossover transitions was found and in each case the crossover transition was estimated to be [Formula: see text] of the cascade transition. Angular correlations of the gamma rays were obtained and these strongly support an assignment of spin 0 to the 3.63-Mev state and a spin of 2 for the 3.92-Mev state. These assignments have been confirmed by a recent experiment on the O16(H3, p)O18 reaction which gives the assignments 0+ and 2+ for these two states. Thus the states at 3.55, 3.63, and 3.92 Mev form a triplet with assignments 4+, 0+, and 2+ which strongly resembles the vibrational spectra found in heavier nuclei. However, the measured angular correlations of the gamma rays from the 3.92-Mev state show only a small admixture of electric quadrupole in the 1.94-Mev gamma ray with relative amplitude +0.1 ±.1. A lower limit of ~10−12 seconds on the lifetime of the 3.63-Mev state was obtained from the absence of a doppler shift of the 1.65-Mev cascade gamma ray.

THE MEASUREMENT AND ANALYSIS OF TRIPLE CORRELATIONS

1964 ◽  
Vol 42 (6) ◽  
pp. 1101-1115 ◽  
Author(s):  
Philip B. Smith
Keyword(s):  
Gamma Rays ◽  
Heavy Particle ◽  
Original Data ◽  
Population Parameters ◽  
True Solution ◽  
Error Matrix ◽  
Mixing Ratios ◽  
Triple Correlation ◽  
Measurement And Analysis

The measurement and analysis of the intensity–direction correlation of gamma rays emitted in cascade following heavy-particle capture are treated. A procedure is discussed which is based upon the expansion of the triple-correlation intensity in terms of the set of angular functions orthogonal over the space of the emission (or absorption) directions. This is in contrast to the usual method which expresses the correlation in terms of Legendre polynomials. In the analysis procedure proposed, the population parameters are found directly from the original data, with the gamma-radiation mixing ratios assigned. The least-squares equations representing the best fit to the data contain the population parameters linearly and are solved by a standard computer program which also gives the value of χ2. The true solution is then found by varying the mixing ratios until a minimum in χ2 is reached. In addition to the determination of the population parameters of the decaying state and the mixing ratios of the gamma rays in the cascade, the calculation of the error matrix of these quantities, and the calculation of the formation parameters in simple capture, are described.

Nuclear g factors of three levels of 192Pt

1969 ◽  
Vol 47 (21) ◽  
pp. 2395-2399 ◽  
Author(s):  
D. B. Kenyon ◽  
L. Keszthelyi ◽  
J. A. Cameron
Keyword(s):  
Hyperfine Field ◽  
Angular Correlation ◽  
Iron Alloy ◽  
Scintillation Detectors ◽  
Angular Correlations ◽  
Mixing Ratios ◽  
G Factors

The g factors of the 316, 612, and 785 keV levels of 192Pt have been measured using gamma–gamma angular correlations perturbed by the hyperfine field in an iron alloy. Sources were 192Ir in 1 at.% Ir Fe alloy. Coincidences were observed using a combination of Ge(Li) and scintillation detectors. For the three levels, the g factors obtained were[Formula: see text]In addition, the E2/M1 mixing ratios were obtained from the angular correlation measurements.[Formula: see text]

Properties of low-lying states in 43Sc

1970 ◽  
Vol 48 (22) ◽  
pp. 2735-2750 ◽  
Author(s):  
G. C. Ball ◽  
J. S. Forster ◽  
F. Ingebretsen ◽  
C. F. Monahan
Keyword(s):  
Excited States ◽  
Gamma Ray ◽  
Level Structure ◽  
Surface Barrier ◽  
Angular Correlations ◽  
Mixing Ratios ◽  
Gamma Coincidence ◽  
Theoretical Predictions ◽  
Barrier Detector ◽  
Coincidence Spectra

The 40Ca(α, pγ)43Sc reaction at Eα = 11.8 to 15.5 MeV has been used to investigate the level structure of 43Sc below 4.2 MeV excitation. Level energies and decay schemes were determined from proton–gamma coincidence spectra obtained using an annular surface barrier detector positioned near 180° and two 40 cm3 Ge(Li) detectors. Angular correlations were measured in the same configuration using an array of six 12.7 × 15.2 cm NaI(Tl) detectors mounted on the Chalk River LOTUS goniometer. Twelve new levels were observed in 43Sc and information on the spins, branching ratios, and gamma-ray multipole mixing ratios of these and several other excited states has been obtained. The results are compared with recent theoretical predictions of Johnstone. In particular, levels at 1931 and 2552 keV, 1830 keV and 1883 keV have been tentatively assigned as the 9/2+ and probable 11/2+ members of the kπ = 3/2+ band, the (fp)3, Jπ = 11/2− state, and the 9/2− member of the kπ = 3/2− band, respectively.

GAMMA-RAY ANGULAR CORRELATION MEASUREMENTS IN Ne22

1964 ◽  
Vol 42 (6) ◽  
pp. 1300-1310 ◽  
Author(s):  
C. Broude ◽  
M. A. Eswaran
Keyword(s):  
Excited State ◽  
Angular Correlation ◽  
Gamma Ray ◽  
Amplitude Ratio ◽  
Spin Assignment ◽  
Primary Radiation ◽  
Angular Correlations ◽  
First Excited State

Coincidence gamma-ray angular correlations of the cascade decays from the 3.34- and 4.47-Mev states in Ne22 through the first excited state have been measured. The levels were excited by the reaction F19 (α, p)Ne22. The correlations give an unambiguous spin assignment of 4 to the 3.34-Mev state; the analysis of the correlations from the 4.47-Mev state is not unique, allowing spin 2 or 3. The quadrupole-to-dipole amplitude ratio for the primary radiation is −0.11 ± 0.03 or −1.07 ± 0.10, respectively, for the spin-2 and spin-3 assignments.

Symmetry property of the electric quadrupole perturbation function in gamma ray angular correlations

1990 ◽  
Vol 113 (4) ◽  
pp. 297-302
Author(s):  
S. Connell ◽  
K. Bharuth-Ram ◽  
H. Appel ◽  
J. P. F. Sellschop ◽  
M. Stemmet
Keyword(s):  
Symmetry Property ◽  
Gamma Ray ◽  
Electric Quadrupole ◽  
Perturbation Function ◽  
Angular Correlations

Gamma rays from the 3702 keV level in 25Al

1969 ◽  
Vol 47 (23) ◽  
pp. 2609-2619 ◽  
Author(s):  
N. Anyas-Weiss ◽  
A. E. Litherland
Keyword(s):  
Angular Distribution ◽  
Lower Limit ◽  
Gamma Rays ◽  
Doppler Shift ◽  
Gamma Ray ◽  
Decay Modes ◽  
Mirror Nucleus ◽  
Mixing Ratios ◽  
Doppler Shift Attenuation ◽  
Decay Gamma

The decay modes of the 7/2−, 3702 keV level in 25Al have been studied at the Ep = 1490 keV resonance in the 24Mg(p,γ)25Al reaction. The decay gamma rays were observed using a 25 cm3 Ge(Li) detector. A previously unreported 2% transition from the resonance to the level at 2723 keV has been observed. The angular distribution of this gamma ray admits only a spin of 7/2 for the 2723 keV level. The lifetime of the 2723 keV level was measured with the Doppler shift attenuation method (DSAM) at the 1660 keV resonance and was found to be [Formula: see text]. The lifetime of the 5/2+, 1790 keV level has been measured using the DSAM and has been found to be [Formula: see text]. From Doppler shift measurements a lower limit for the lifetime of the 3/2+, 945 keV level of [Formula: see text] was obtained. From angular distribution measurements at the Ep = 1490 keV resonance, the following multipole mixing ratios have been measured: δ(R → 0) = 0.00 ± 0.02; δ(R → 1790) = −0.02 ± 0.02; δ(R → 2723) = 0.15 ± 0.30; [Formula: see text]; δ(1790 → 945) = −0.15 ± 0.05; δ(945 → 0) = 0.35 ± 0.10 or 1.7 ± 0.2; δ(945 → 451) = −0.15 ± 0.05 or 2.6 ± 0.4. Comparisons with data in the mirror nucleus 25Mg have been made.

K X-Ray and Gamma-Ray Angular Correlations in the Decay of 113Sn and 133Ba, using a High Efficiency Sum-Peak Coincidence Scintillation Spectrometer

1971 ◽  
Vol 49 (13) ◽  
pp. 1769-1772 ◽  
Author(s):  
K. Venkata Ramana Rao ◽  
V. Lakshminarayana
Keyword(s):  
Angular Correlation ◽  
Beta Decay ◽  
High Efficiency ◽  
Gamma Ray ◽  
X Ray ◽  
Angular Correlations ◽  
Nuclear Environment

K-capture isotopes 113Sn and 133Ba are used with a sum-peak coincidence scintillation spectrometer arrangement to study the K X-ray – gamma-ray angular correlation. The effects of the type of beta decay, the nuclear environment, and three-gamma cascades with intermediate gamma ray unobserved are investigated. No anisotropy could be detected, supporting the theory of Dolginov.

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