A Study of Levels in 25Mg via the 22Ne(α, nγ)25Mg Reaction

1972 ◽  
Vol 50 (13) ◽  
pp. 1539-1553 ◽  
Author(s):  
D. C. Kean ◽  
R. W. Ollerhead
Keyword(s):  
Gamma Rays ◽  
Ground State ◽  
Branching Ratios ◽  
Angular Distributions ◽  
Rotational Model ◽  
Mixing Ratios ◽  
Decay Properties ◽  
Decay Branch ◽  
Band Mixing ◽  
Good Agreement

Levels in the nucleus 25Mg have been studied by measurement of the angular distributions and polarization of gamma rays from the 22Ne(α, nγ)25Mg reaction. Information regarding spins, parities, mixing ratios, and branching ratios has been obtained for the levels between 2.7 and 4.7 MeV excitation. Spin and parity assignments of 5/2+ and 7/2− have been made to the levels at 3.90 and 3.97 MeV. Mixing ratios have been determined or restricted for most of the observed transitions. The decay branch of the 3.40 MeV level to the ground state is found to be considerably stronger than previously reported, bringing the decay properties of this level into good agreement with the predictions of the simple rotational model. The significance of the results within the framework of the rotational model is discussed. There is evidence for considerable band mixing in levels belonging to the second Kπ = 1/2+ and the Kπ = 1/2− bands.

Properties of the 2.645, 2.693, 3.001, and 3.162 MeV levels in 35Cl

1970 ◽  
Vol 48 (5) ◽  
pp. 603-615 ◽  
Author(s):  
P. Taras ◽  
J. Matas
Keyword(s):  
Gamma Rays ◽  
Ground State ◽  
Branching Ratios ◽  
Angular Distributions ◽  
Mixing Ratios ◽  
Four Levels

Angular distributions and linear polarizations of the gamma rays emitted in the 35Cl(p, p′γ)35Cl reaction have been measured. Four resonances were investigated at proton energies of 4.24, 4.82, 5.08, and 5.11 MeV. The spin and parity of the levels at 2.645, 2.693, and 3.001 MeV in 35Cl have been deduced to be 7/2+, 3/2+, and 5/2+, respectively, while the spin and parity of the 3.162 MeV level have been confirmed to be 7/2−. The multipolarity mixing ratios of the decay of these four levels to the ground state have been found to be δ(M3/E2) = 0, δ(E2/M1) = +0.26 ± 0.03, δ(E2/M1) = +0.07 ± 0.02, and δ(E3/M2) = −0.25 ± 0.04, respectively. In addition, the branching ratios for the decay of these four levels have been determined.

Radiative decay of unbound levels in 14N

1985 ◽  
Vol 63 (9) ◽  
pp. 1141-1147 ◽  
Author(s):  
C. Pruneau ◽  
M. B. Chatterjee ◽  
C. Rangacharyulu ◽  
C. St-Pierre
Keyword(s):  
Shell Model ◽  
Radiative Decay ◽  
Branching Ratios ◽  
Gamma Transition ◽  
Model Calculations ◽  
Mixing Ratios ◽  
Decay Properties ◽  
Decay Widths ◽  
Gamma Decay ◽  
Good Agreement

The gamma decay properties of 10.43-, 10.1-, 9.7-, 9.51-, and 8.91-MeV levels are studied by the 13C(p, γ) reaction. The natural widths, gamma decay widths, branching ratios, and multipole mixing ratios are determined. The gamma branching ratios are generally in good agreement with earlier works. However, it is found that the previous (p, γ) measurements overestimated the gamma transition strengths. The results are compared with shell model calculations. Also, a phenomenological description is attempted for a few 14N levels.

High-Spin States in 23Na

1973 ◽  
Vol 51 (11) ◽  
pp. 1155-1169 ◽  
Author(s):  
G. G. Frank ◽  
R. V. Elliott ◽  
R. H. Spear ◽  
J. A. Kuehner
Keyword(s):  
Ground State ◽  
Branching Ratios ◽  
Angular Distributions ◽  
Spin States ◽  
High Spin States ◽  
Doppler Shift Attenuation ◽  
Nilsson Model ◽  
Γ Rays ◽  
Band Mixing ◽  
Γ Ray

The 12C(12C,pγ)23Na reaction has been used to study the γ-ray deexcitation of levels up to Ex = 10.4 MeV in 23Na. Doppler-shift attenuation measurements yielded mean lifetimes or lifetime limits for 22 levels. Branching ratios were obtained for the 5.54, 6.11, 6.24, and 6.35 MeV levels and the major modes of decay were observed for 7 levels above Ex = 7 MeV. Angular distributions were measured for γ rays in coincidence with proton groups corresponding to the 5.54, 6.11, 6.24, 6.35, 9.04, and 10.35 MeV levels. The 6.35 MeV level is assigned a spin and parity of 9/2− and interpreted as a member of the low-lying Kπ = 1/2− band in 23Na. Levels at 9.04 and 10.35 MeV are interpreted as the 15/2+ and 13/2− members of the ground-state rotational band and Kπ = 1/2− band, respectively. The experimental γ-ray transition strengths in 23Na are compared to those predicted by the Nilsson model including band mixing. The M1 strengths are modified to account for the effects of isospin.

scholarly journals Excitation of the Ground-State Rotational Band in 28Si by Inelastic Scattering of 25.25 MeV Polarized Protons

1973 ◽  
Vol 51 (12) ◽  
pp. 1293-1299 ◽  
Author(s):  
R. de Swiniarski ◽  
H. E. Conzett ◽  
C. R. Lamontagne ◽  
B. Frois ◽  
R. J. Slobodrian
Keyword(s):  
Inelastic Scattering ◽  
Cross Sections ◽  
Ground State ◽  
Optical Potential ◽  
Great Sensitivity ◽  
Angular Distributions ◽  
Rotational Model ◽  
Coupled Channels ◽  
Polarized Protons ◽  
State Band

Angular distributions of the analyzing power and cross sections have been measured for the elastic and inelastic scattering of 25.25 MeV protons exciting the K = 0+ ground-state band in 28Si. Good agreement with experiment is obtained in the coupled-channels formalism on the basis of the rotational model with a quadrupole deformation β2 = −0.40 (oblate) and a hexadecapole deformation β4 = +0.15. The calculations show the great sensitivity of the experimental results to both the magnitude and sign of the quadrupole and hexadecapole deformations. Equivalent fits of the data were obtained either by keeping the deformation length of the various deformed terms of the optical potential constant (δ0 = β0R0 = βIRI = βLSRLS) or by increasing the deformation of the spin–orbit optical potential relative to the central potential by a factor of 1.5 (βLS = 1.5βcent).

Nuclear g Factors in 55Fe

1973 ◽  
Vol 51 (7) ◽  
pp. 707-712 ◽  
Author(s):  
P. G. Kerr ◽  
A. W. Gibb ◽  
J. A. Cameron
Keyword(s):  
Excited States ◽  
Gamma Rays ◽  
Target Material ◽  
Internal Field ◽  
Angular Distributions ◽  
Mixing Ratios ◽  
Decay Gamma ◽  
G Factors

The (α,n) reaction on natural chromium has been used to study levels in 55Fe up to 2.5 MeV excitation. Intensities and angular distributions of the decay gamma rays were measured, yielding branching and E2/M1 mixing ratios. In a magnetized target of the alloy Cr20Fe80, the rotation of the angular distributions was observed. Using recently determined lifetimes for the excited states and the average internal field of 277 kOe measured in the target material by Mössbauer absorption, the following g factors are obtained:[Formula: see text]

Proton?Capture Gamma Rays from Nitrogen?13

1962 ◽  
Vol 15 (3) ◽  
pp. 443 ◽  
Author(s):  
AW Parker ◽  
GG Shute
Keyword(s):  
Angular Distribution ◽  
Excited State ◽  
Elastic Scattering ◽  
Gamma Rays ◽  
Ground State ◽  
Recent Experiment ◽  
Gamma Ray ◽  
Angular Distributions ◽  
Proton Capture ◽  
Yield Curves

From a recent experiment in this laboratory (Shute et al. 1962) on the elastic scattering of protons from 12C, resonance levels (E13N, J1t) of 13N were obtained at the laboratory bombarding energies (Ep) shown in Table 1. To confirm these results, an investigation of the yield and angular distribution of gamma rays from the reaction 12C(p'YO)13N and 12C(p'Yl)13N was undertaken. Accordingly, the theoretical angular distributions, W(8), for the gamma ray (Yo) to the ground state of 13Na-) and also for the gamma ray (Yl) to the 1st excited state of 13Na+) were evaluated on the assumptions that overlap of levels in 13N is small and lowest order multipoles are involved. As angular distributions are parity insensitive, these were found to be identical for the two gamma rays expected. The simpler of these angular distributions are also shown on the table. The expected angular distributions indicate that 90� is a suitable angle for yield curves.

SUCCESSIVE DECAYS FROM Pr137 AND Ce137m: DECAY OF ADJACENT PRASEODYMIUM ISOTOPES

1958 ◽  
Vol 36 (11) ◽  
pp. 1487-1508 ◽  
Author(s):  
G. T. Danby ◽  
J. S. Foster ◽  
A. L. Thompson
Keyword(s):  
Excited State ◽  
Small Group ◽  
Electron Capture ◽  
High Spin ◽  
Gamma Rays ◽  
Isomeric State ◽  
Ground State ◽  
Branching Ratios ◽  
Spin States ◽  
High Spin States

The decay of Pr137 entirely to a 9.0-hour ground state of Ce137 was independently discovered. By allowed electron capture, Ce137 decays predominantly to a low-lying state of La137, with only a 3% branching to a 440-kev excited state. The 440-kev transition is at least predominantly E2 in character.A 34.4-hour isomeric state produced by the La139(p, 3n)Ce137m reaction decays by a 254.5-kev M4 transition to the 9-hour -ground state. A 0.6% branching was found from the isomeric state directly to a small group of apparently high spin states in La137.Studies of mass-separated isotopes confirmed the existence of 1.5-hour Pr137 and 1.0-hour Pr136. The K-capture to positron branching ratios observed in the decay of Pr139, Pr138, Pr137, and Pr136 show that these isotopes decay by allowed transitions to their cerium daughters. Characteristic gamma rays were observed.

Lifetimes and decay modes of low-lying levels in 26Mg and 26Al

1968 ◽  
Vol 46 (9) ◽  
pp. 1035-1050 ◽  
Author(s):  
O. Häusser ◽  
T. K. Alexander ◽  
C. Broude
Keyword(s):  
Excitation Energy ◽  
Excited States ◽  
Gamma Rays ◽  
Doppler Shift ◽  
Bound States ◽  
Branching Ratios ◽  
Decay Modes ◽  
Rotational Bands ◽  
Decay Properties

Several bound states with excitation energy up to 7 MeV were studied in 26Mg, using the 26Mg(p, p′γ) reaction. The attenuated Doppler shift of the de excitation gamma rays was observed with a Ge(Li) spectrometer. The extracted lifetime estimates and branching ratios for 15 excited states suggest that the rotational bands, built on different intrinsic states, are mixed considerably. Incidental information on lifetimes and decay properties of states in 26Al is also presented.

14.—Ground State Rotational Bands in 158Dy, 160Dy and 162Dy

1972 ◽  
Vol 70 ◽  
pp. 155-163 ◽  
Author(s):  
G. T. Ewan ◽  
G. I. Andersson
Keyword(s):  
Gamma Rays ◽  
Ground State ◽  
Gamma Ray ◽  
Angular Distributions ◽  
Rotational Bands ◽  
Weak Evidence ◽  
Gamma Coincidence ◽  
Inertia Model ◽  
Coincidence Spectra ◽  
Variable Moment

SynopsisLevels in the ground state bands of 158Dy, 160Dy and 162Dy have been populated by (α, 2n) reactions on metallic targets of separated 156Gd, 158Gd and 160Gd isotopes. Two Ge(Li) detectors were used to study singles gamma-ray spectra, gamma-ray angular distributions, gamma-gamma coincidence spectra and relative yields of gamma-rays for bombarding energies from 20 to 27 MeV. Transitions from all levels in the ground state bands up to the 12+ member were identified and the following level energies in keV established: 158Dy: 0 (0+), 99·0 (2+), 317·4 (4+), 637·9 (6+), 1044·1 (8+), 1520·1 (10+) and 2049·4 (12+); 160Dy: 0 (0+), 86·7 (2+), 283·7 (4+), 581·4 (6+), 967·4 (8+), 1429·0 (10+), 1951·7 (12+); 162Dy: 0 (0+), 80·7 (2+), 265·7 (4+), 548·5 (6+), 921·1 (8+), 1374·8 (10+) and 1901·0 (12+). There is weak evidence for the 14+ levels in 158Dy and 160Dy. The level energies are compared with calculated values using the variable moment of inertia model.

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