EXCITED STATES OF 11C FROM n–γ ANGULAR CORRELATK AND GAMMA BRANCHING RATIOS

1966 ◽  
Vol 44 (6) ◽  
pp. 1213-1223 ◽  
Author(s):  
A. S. Rupaal ◽  
B. L. White ◽  
J. R. Prescott
Keyword(s):  
Experimental Study ◽  
Excited States ◽  
Ground State ◽  
Gamma Ray ◽  
High Energy ◽  
Branching Ratios ◽  
Intermediate Coupling ◽  
Angular Correlations ◽  
Gamma Transitions ◽  
Bombarding Energy

An experimental study of excited states of 11C below 6.5 MeV has been made using the 10B (d, nγ)11C reaction at a deuteron bombarding energy of 0.8 MeV. Measurements were made of the n–γ angular correlations of the ground-state gamma transitions from the 6.49- and 4.32-MeV levels, and of the gamma-ray branching ratios from the 6.49-, 4.81-, and 4.32-MeV levels.Theoretical analysis of the n–γ angular correlations suggests that the J values of the 6.49- and 4.32-MeV levels are (3/2), (5/2), or (7/2). The parities of all the states observed in this experiment are already known to be negative from high-energy stripping data. A comparison of the experimental branching ratios with theoretical branching ratios predicted by the intermediate coupling shell model is consistent with the following spin and parity assignments in 11C: ground state (3/2)−, 2.00 MeV (1/2)−, 4.32 MeV (5/2)−, 4.81 MeV (3/2)−, and 6.49 MeV (7/2)−.

Puzzle for the existence of 3α + N structure in A=13 system

2006 ◽  
Vol 21 (31n33) ◽  
pp. 2411-2417 ◽  
Author(s):  
Mamoru Fujiwara ◽  
Hisako Fujimura
Keyword(s):  
Excited States ◽  
High Energy ◽  
Branching Ratios ◽  
Wave Functions ◽  
Direct Reaction ◽  
View Point ◽  
Intermediate Energies ◽  
Zero Degree ◽  
Bombarding Energy ◽  
Gamow Teller

Spin-isospin excitations in 13 N have been studied by means of the (3 He ,t) and (3 He ,tp) reactions at the bombarding energy of E(3 He ) = 450 MeV . The zero-degree (3 He ,t) spectrum is found to be similar to those from the (p,n) reactions at intermediate energies, suggesting a simple direct reaction mechanism at E(3 He ) = 450 MeV . Three pairs of Gamow-Teller (GT) states with Jπ = 1/2- and 3/2- have been strongly excited at θlab. = 0°. Microscopic structures of the states in 13 N have been studied by observing decay protons in coincidence with high energy tritons measured at θlab. = 0°. The branching ratios for proton decay from the GT states in 13 N to the final low-lying T =0 states in 12 C were obtained. The wave functions of the excited states in 13 N are discussed in the view point of α cluster model.

Gamma-Ray Angular Correlations and Lifetime Measurements for Some Excited States ofNe21

1969 ◽  
Vol 186 (4) ◽  
pp. 1174-1188 ◽  
Author(s):  
J. G. Pronko ◽  
C. Rolfs ◽  
H. J. Maier
Keyword(s):  
Excited States ◽  
Gamma Ray ◽  
Lifetime Measurements ◽  
Angular Correlations

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.

scholarly journals Determination of GT-transition Strengths in \(A=34\) Isobars Using Charge Exchange \((^3\text{He},t)\) Reaction

2012 ◽  
Vol 22 (1) ◽  
pp. 91-96
Author(s):  
Nguyen Tuan Khai ◽  
Bui Duy Linh ◽  
Tran Duc Thiep ◽  
Y. Fujita ◽  
T Adachi ◽  
...  
Keyword(s):  
Excitation Energy ◽  
Excited States ◽  
Ground State ◽  
Incident Energy ◽  
High Energy ◽  
High Energy Resolution ◽  
Good Quantum Number ◽  
Gamow Teller ◽  
Good Agreement

Under the assumption that isospin \(T\) is a good quantum number, mirror transitions \(T_{z }= +1 \to  0\) and \(T_{z }= -1  \to  0\) were studied in \(A = 34\) isobars, where \(T_{z}\) is \(z\) component of iospin \(T\) and is defined by \(T_{z} = (N-Z)/2\). With a high energy resolution of 35 keV in \(^{34}\)S\((^{3}He,t)^{34}\)Cl reaction measurement at \(0^{\circ}\) scattering angle and at an incident energy of 140 MeV/nucleon, strengths of Fermi and Gamow-Teller (GT) transitions from the \(J^{\pi } = 0^{ + }\), \(T_{z }= +1\) ground state of \(^{34}\)S to the \(J^{\pi } = 1^{+ }\), \(T_{z }= 0\) excited states in \(^{34}\)Cl were determined up to excitation energy \((E_{x})\) of \(7.08\) MeV. The corresponding isospin-symmetric transitions connecting \(T_{z }= -1\) and \(T_{z }= 0\) states can be studied in the \(^{34}\)Ar \(\beta ^{ + }\) decay. The strengths of the \((GT)_{\pm }\) transitions were compared up to the excitation energy of 3.1 MeV. A good agreement was observed for two strong transitions to \(2.580\) MeV and \(3.129\) MeV states, while a disagreement about \(45\text{%}\) was observed for a weaker transition to \(0.666\) MeV low-lying state.

scholarly journals Electron Scattering from the Ground and Excited States of Barium

1999 ◽  
Vol 52 (3) ◽  
pp. 603
Author(s):  
Dmitry V. Fursa
Keyword(s):  
Excited States ◽  
Electron Scattering ◽  
Cross Sections ◽  
Differential Cross ◽  
Ground State ◽  
Differential Cross Sections ◽  
Close Coupling ◽  
Angular Correlations ◽  
Electron Photon ◽  
Good Agreement

We have used the nonrelativistic convergent close-coupling (CCC) method to investigate electron scattering from the ground (6s2)1S state and excited (6s6p)1 Po1 and (6s5d)1,3De2 states of barium. For the scattering from the barium ground state, we have found very good agreement with measurements of (6s6p)1 Po1 apparent cross sections at all energies. Similarly, good agreement is found for differential cross sections for elastic scattering and (6s6p)1 Po and (6s5d)1 De2 excitations and with the (6s6p)1 Po1 state electron{photon angular correlations. For the scattering from excited states of barium we have found good agreement with elastic (6s6p)1 Po1 scattering and the (6s5d)1De2 → (6s6p)1 Po1 transition for both differential cross sections and electron–photon angular correlations.

Study of thermal neutron capture in potassium

1970 ◽  
Vol 48 (10) ◽  
pp. 1109-1129 ◽  
Author(s):  
L. V. Johnson ◽  
T. J. Kennett
Keyword(s):  
Thermal Neutron ◽  
Excited States ◽  
Neutron Capture ◽  
Decay Scheme ◽  
Gamma Ray ◽  
Branching Ratios ◽  
Experimental Results ◽  
Thermal Neutron Capture ◽  
Gamma Coincidence

The 39K(n,γ)40K reaction has been studied using a Ge(Li) and a Ge(Li)–Ge(Li) spectrometer. A total of 252 gamma-ray transitions has been observed and a gamma–gamma coincidence matrix involving 62 transitions has been established. A decay scheme based on the experimental results is deduced for 202 of the observed gamma-ray transitions. Spins and parities of some excited states have been estimated from the deduced branching ratios. The neutron separation energies of the 40K and 42K nuclei have been determined as 7800.5 ± 0.2 and 7535.2 ± 1.5 keV respectively.

Lifetimes and branching ratios of energy levels of 28Si. I

1969 ◽  
Vol 47 (6) ◽  
pp. 639-649 ◽  
Author(s):  
A. E. Litherland ◽  
P. J. M. Smulders ◽  
T. K. Alexander
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Energy Levels ◽  
Ground Level ◽  
Particle Beam ◽  
High Energy ◽  
Branching Ratios ◽  
Alpha Particles ◽  
Doppler Shift Attenuation ◽  
Energy Gamma

The gamma rays from the 25Mg(α,nγ)28Si reaction have been studied using alpha particles with energies ranging from 4.8 to 6.0 MeV. A 25 cm3 Ge(Li) gamma-ray counter was used to observe the complex high energy gamma-ray spectra at angles between 0° and 130° to the alpha-particle beam. Estimates of the nuclear lifetimes of the energy levels excited were obtained from Doppler shift attenuation measurements. The de-excitation branching ratios of the levels were also measured. The existence of a new level in 28Si at 6695 keV was confirmed. The recently reported 3− level at either 6880 keV or 6889 keV was observed and found to be the 6880-keV member of the doublet. The enhancement of the octupole transition to the ground level of 28Si was found to be 13 Weisskopf units.

Photoneutrons from 19F

1976 ◽  
Vol 54 (11) ◽  
pp. 1178-1189 ◽  
Author(s):  
N. K. Sherman ◽  
K. H. Lokan ◽  
R. W. Gellie
Keyword(s):  
Excited States ◽  
Cross Section ◽  
Electric Dipole ◽  
Ground State ◽  
Time Of Flight ◽  
Branching Ratios ◽  
Integrated Cross Section ◽  
Time Of Flight Method

The 19F(γ,n) reaction was studied by irradiating teflon with bremsstrahlung of energy increasing from 13 MeV to 21 MeV in 1 MeV steps. Photoneutron spectra were measured by the time-of-flight method. Excited states of 19F at 12.10, 12.38, 13.82, and 16.24 MeV were observed. The total integrated cross section between 11.9 and 17.9 MeV was found to be (14.4 ± 2.2) MeV mb. Branching ratios to the first group of excited states of 18F compared to the ground state were measured, along with resonance widths and approximate radiative widths. They are consistent with the interpretation that all four states arise from electric dipole d → f valence transitions, with the first two states having Jπ = 1/2−, and the second two having 3/2−.

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.

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