Lifetimes and decay modes of energy levels in 25Mg

1968 ◽  
Vol 46 (18) ◽  
pp. 2039-2053 ◽  
Author(s):  
J. F. Sharpey-Schafer ◽  
R. W. Ollerhead ◽  
A. J. Ferguson ◽  
A. E. Litherland
Keyword(s):  
Gamma Rays ◽  
Doppler Shift ◽  
Energy Levels ◽  
Branching Ratios ◽  
Collective Model ◽  
Incident Proton ◽  
Crystal Spectrometer ◽  
Decay Modes ◽  
Mirror Nucleus ◽  
Doppler Shift Attenuation

Lifetimes of energy levels in 25Mg have been measured using the Doppler-shift attenuation method. The levels were exicted by the 25Mg(p, p′γ) reaction with incident proton energies between 3.8 and 7.0 MeV. The gamma rays were detected in a three-crystal spectrometer consisting of a 40 cm3 Ge(Li) detector surrounded by a large NaI(Tl) crystal in the form of a split annulus. Mean lifetimes found, given in fs, are: τ(1611-keV level) = [Formula: see text], τ(1962) = [Formula: see text], τ(2565) = 59 ± 26, τ(2736) = 288 ± 20, τ(2803) = 27 ± 6, τ(3399) = 33 ± 19, τ(3408) < 20, τ(3903) < 20, τ(3969) = 24 ± 11, τ(4055) = 53 ± 10, and τ(5005) < 26. The decay modes and branching ratios of levels up to 4055-keV excitation are given. The results are compared with the mirror nucleus 25Al and discussed in terms of the collective model.

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.

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.

Mesures de Rapports d'Embranchement et de Vies Moyennes dans 30Si

1972 ◽  
Vol 50 (3) ◽  
pp. 278-286 ◽  
Author(s):  
A. Gallmann ◽  
F. Haas ◽  
M. Toulemonde
Keyword(s):  
Shell Model ◽  
Gamma Rays ◽  
Doppler Shift ◽  
Branching Ratios ◽  
Matrix Elements ◽  
Excitation Energies ◽  
Doppler Shift Attenuation ◽  
Annular Detector ◽  
Γ Rays

Gamma rays from the decay of 30Si levels with excitation energies less than 6.0 MeV have been studied by the 27Al(α, pγ)30Si reaction. The γ rays were detected in a Ge(Li) detector in coincidence with protons observed in an annular detector placed at 180°. Branching ratios and lifetimes have been extracted. The lifetimes have been measured by the Doppler-shift attenuation method.The electromagnetic matrix elements for some of the observed levels were compared with recent many-particle shell model and core-coupling calculations.

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.

Properties of the 9.699 MeV level in 28Si

1969 ◽  
Vol 47 (16) ◽  
pp. 1725-1729 ◽  
Author(s):  
N. Anyas-Weiss ◽  
A. M. Charlesworth ◽  
L. E. Carlson ◽  
K. P. Jackson ◽  
R. E. Azuma
Keyword(s):  
Lower Limit ◽  
Gamma Rays ◽  
Large Volume ◽  
Doppler Shift ◽  
Branching Ratios ◽  
Doppler Shift Attenuation ◽  
Doppler Shift Attenuation Method

The decay of the 9.699 MeV level in 28Si has been studied using the reaction 27Al(p,γ)28Si at Ep = 1724 keV. Gamma rays from the decay of the 9.699 MeV level were observed with large-volume Ge(Li) detectors. Branching ratios for the decay of the 9.699 MeV level have been obtained and a lower limit for the lifetime of this level has been measured to be [Formula: see text] using the Doppler-shift attenuation method.

Lifetime measurements of the six lowest lying levels in 35Cl

1969 ◽  
Vol 47 (12) ◽  
pp. 1295-1306 ◽  
Author(s):  
F. Ingebretsen ◽  
T. K. Alexander ◽  
O. Häusser ◽  
D. Pelte
Keyword(s):  
Gamma Rays ◽  
Doppler Shift ◽  
Gamma Ray ◽  
Level Structure ◽  
Branching Ratios ◽  
Distance Method ◽  
Lifetime Measurements ◽  
Mixing Ratios ◽  
Doppler Shift Attenuation ◽  
Recoil Distance

The energies, gamma-ray branching ratios, and mean nuclear lifetimes of the six lowest lying levels in 35Cl have been measured. Gamma rays following the reaction 32S(α,pγ)35Cl were studied using two Ge(Li) detectors with 15-cm3 and 40-cm3 active volumes respectively. The lifetimes of the five lowest lying levels were measured using the Doppler shift attenuation method, with the results: 1219 keV, [Formula: see text]; 1763 keV, 0.55 ± 0.15 ps; 2646 keV, 0.30 ± 0.09 ps; 2695 keV, <0.03 ps; and 3003 keV, <0.05 ps. The lifetime of the 3163-keV level was measured to be 60 ± 7 ps, using a recoil distance method. The level structure is discussed taking into account known lifetimes, spins, parities, and gamma-ray mixing ratios.

LIFETIME MEASUREMENTS OF STATES IN O18 AND Ne22

1964 ◽  
Vol 42 (6) ◽  
pp. 1311-1323 ◽  
Author(s):  
M. A. Eswaran ◽  
C. Broude
Keyword(s):  
Excited State ◽  
Ground State ◽  
Doppler Shift ◽  
State Transition ◽  
Branching Ratios ◽  
Ground State Transition ◽  
Lifetime Measurements ◽  
Doppler Shift Attenuation ◽  
First Excited State ◽  
Doppler Shift Attenuation Method

Lifetime measurements have been made by the Doppler-shift attenuation method for the 1.98-, 3.63-, 3.92-, and 4.45-Mev states in O18 and the 1.28-, 3.34-, and 4.47-Mev states in Ne22, excited by the reactions Li7(C12, pγ)O18 and Li7(O16, pγ)Ne22. Branching ratios have also been measured. The results are tabulated.[Formula: see text]The decay of the 3.92-Mev state in O18 is 93.5% to the 1.98-Mev state and 6.5% to the ground state and of the 4.45-Mev state 74% to the 3.63-Mev state, 26% to the 1.98-Mev state, and less than 2% to the ground state. In Ne22, the ground-state transition from the 4.47-Mev state is less than 2% of the decay to the first excited state.

Study of the Decay of the 3.696 MeV Level in 25Al

1971 ◽  
Vol 49 (4) ◽  
pp. 467-474 ◽  
Author(s):  
G. J. McCallum ◽  
R. J. Sparks ◽  
G. E. Coote ◽  
K. P. Pohl
Keyword(s):  
Doppler Shift ◽  
Gamma Ray ◽  
Branching Ratios ◽  
Angular Distributions ◽  
Doppler Shift Attenuation ◽  
Doppler Shift Attenuation Method

The decay of the 3.696 MeV level in 25Al has been studied by means of the 24Mg(p,γ)25Al reaction at the 1.49 MeV resonance. Gamma-ray branching ratios, direct angular distributions, and lifetimes determined by the Doppler shift attenuation method are reported.

Lifetimes of low-lying states in 28Si

1969 ◽  
Vol 47 (22) ◽  
pp. 2539-2543 ◽  
Author(s):  
M. Bister ◽  
A. Anttila ◽  
J. Räsänen
Keyword(s):  
Doppler Shift ◽  
Conventional Treatment ◽  
Energy Levels ◽  
Large Angle ◽  
Slowing Down ◽  
Doppler Shift Attenuation ◽  
Doppler Shift Attenuation Method ◽  
Shift Data

The lifetimes of the four first excited energy levels of 28Si have been measured using the Doppler-shift attenuation method in the 27Al(p,γ)28Si reaction. In the analysis of the Doppler-shift data, the effect of the inelastic large-angle collisions in the slowing-down process was estimated in addition to the conventional treatment.

Excited States in 53Mn by the 53Cr(p,nγ)53Mn Reaction

1973 ◽  
Vol 51 (17) ◽  
pp. 1840-1849 ◽  
Author(s):  
Woon-Hyuk Chung ◽  
D. M. Sheppard ◽  
W. C. Olsen ◽  
B. C. Robertson
Keyword(s):  
Statistical Model ◽  
Excited States ◽  
Energy Levels ◽  
Branching Ratios ◽  
Angular Distributions ◽  
Reaction Energy ◽  
Yield Curves ◽  
Mixing Ratios ◽  
Doppler Shift Attenuation ◽  
Γ Ray

The properties of the low-lying excited states in 53Mn were studied by measuring γ-ray angular distributions and lifetimes using the 53Cr(p,nγ)53Mn reaction. Energy levels of 53Mn have been found at 0.378, 1.288, 1.440, 1.619, 2.272, 2.405, 2.572, 2.670, 2.687, 2.705, 2.872, 2.876, 2.914, 2.947, 3.005, 3.095, 3.125, 3.183, 3.193, and 3.250 MeV. The measurement of γ-ray angular distributions and yield curves together with predictions based on the compound nuclear statistical model have enabled spin assignments to be made to the following excited states in 53Mn: 1.440 MeV (11/2), 1.619 MeV (9/2), 2.572 MeV (7/2), 2.687 MeV (7/2), 2.947 MeV (9/2), 3.005 MeV (5/2). Multipole mixing ratios and branching ratios were determined for some of the observed transitions. Lifetimes of nine excited states in 53Mn have been measured using the Doppler-shift attenuation method.

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