Lifetimes and decay of the 2.07 MeV triplet in 26Al

1968 ◽  
Vol 46 (24) ◽  
pp. 2809-2814 ◽  
Author(s):  
O. Häusser ◽  
N. Anyas-Weiss
Keyword(s):  
Gamma Rays ◽  
Ground State ◽  
Doppler Shift ◽  
Excitation Energies ◽  
Upper Limit ◽  
Mean Lifetime ◽  
The Mean ◽  
Γ Ray

Gamma rays from resonances at Ep = 956, 1199, 1287, and 1701 keV in the reaction 25Mg(p,γ)26Al have been studied using 40 cm3 and 25 cm3 Ge(Li) detectors. Accurate γ-ray energy determinations and Doppler shift measurements indicate the existence of three levels at excitation energies of 2068.7, 2069.5, and 2071.7 keV. The level at 2068.7 keV has a mean lifetime of [Formula: see text] and decays 29% to the ground state, and 71% to the 416.6 keV level. The 2069.5 keV level has a mean lifetime of (1.3 ± 0.5) × 10−14 s and decays 5% to the 228.2, 22% to the 416.6, and 73% to the 1057.7 keV levels. The level at 2071.7 keV has a lifetime of [Formula: see text] and decays to the 228.2 keV (> 65%) and the 1057.7 keV (< 35%) levels. An upper limit of τ < 10−14 s has been placed on the lifetime of the 3159.4 keV level and the mean lifetime of the 1850.8 keV level has been measured to be (1.6 ± 0.7) × 10−14 s.

CALCULATING MEAN EXCITATION ENERGY FROM SHANNON INFORMATION ENTROPY FOR K–Xe ATOMS

2003 ◽  
Vol 14 (02) ◽  
pp. 221-224
Author(s):  
M. SOLIMANNEJAD ◽  
A. H. PAKIARI
Keyword(s):  
Shannon Entropy ◽  
Information Entropy ◽  
Ground State ◽  
Periodic Table ◽  
Excitation Energies ◽  
Hartree Fock ◽  
Mean Excitation Energy ◽  
Shannon Information Entropy ◽  
The Mean ◽  
First Time

The calculation of the Shannon entropy of Hartree–Fock electron density is reported for the K–Xe atoms in the fourth and fifth rows of the periodic table in the ground state. In local plasma approximation, the Shannon entropy calculated is used directly to estimate mean excitation energies. To our knowledge, the mean excitation energies of K–Xe atoms are presented here for the first time.

NEUTRON CAPTURE GAMMA RAYS FROM FLUORINE, MAGNESIUM, GALLIUM, BROMINE, AND HAFNIUM

1957 ◽  
Vol 35 (12) ◽  
pp. 1361-1379 ◽  
Author(s):  
P. J. Campion ◽  
G. A. Bartholomew
Keyword(s):  
Energy Range ◽  
Gamma Rays ◽  
Ground State ◽  
Neutron Capture ◽  
State Transition ◽  
High Energy ◽  
The Other ◽  
Ground State Transition ◽  
Γ Rays ◽  
Γ Ray

The neutron capture γ-ray spectra of fluorine, magnesium, gallium, bromine, and hafnium have been studied in the energy range above 3 Mev. In fluorine four γ-rays and in magnesium 12 γ-rays have been detected in addition to those previously observed. Most of these new radiations can be assigned to the known level schemes of the product nuclei. The spectrum obtained for each of the other elements is complex with only a few of the high energy γ-rays resolved, and in each case the γ-ray of highest energy is very weak and difficult to distinguish from the background. The most energetic gallium γ-ray at 7.73 ± 0.02 Mev. may be emitted in the direct ground state transition in Ga70 while the 7.879 ± 0.013 Mev. γ-ray from bromine probably corresponds to the ground state transition in Br80. In hafnium none of the observed γ-rays can be identified with a ground state transition in any of the isotopes.

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.

Excitation Energy of the Fourth Excited State in 18F

1972 ◽  
Vol 50 (14) ◽  
pp. 1682-1684 ◽  
Author(s):  
I. Berka ◽  
C. Rolfs ◽  
R. E. Azuma
Keyword(s):  
Excited State ◽  
Excitation Energy ◽  
Coincidence Measurement ◽  
Resonant States ◽  
Mean Lifetime ◽  
First Excited State ◽  
Γ Rays ◽  
The Mean ◽  
Γ Ray

The excitation energy of the Jπ = 5+, fourth excited state in 18F has been determined to be Ex = 1119.0 ± 0.6 keV from a measurement of the energy of the γ-ray transition to the 937 keV, first excited state. This new excitation energy removes the discrepancies in the excitation energy of resonant states based on γ-ray decay schemes involving this state. The mean lifetime has been determined to be τ(1119) = 218 ± 8 ns by a delayed coincidence measurement between the γ rays populating and deexciting this state.

GAMMA-RAY TRANSITIONS IN 15O AND 15N

1965 ◽  
Vol 43 (12) ◽  
pp. 2310-2318 ◽  
Author(s):  
T. K. Alexander ◽  
A. E. Litherland ◽  
C. Broude
Keyword(s):  
Excited States ◽  
Gamma Rays ◽  
Doppler Shift ◽  
Gamma Ray ◽  
Measured Energy ◽  
The Mean ◽  
The Difference ◽  
Mean Lifetimes

The gamma rays from the first two excited states of 15O and 15N populated by the 14N + d, T(16O, αγ)15N, and 16O(3He, αγ)15O reactions have been observed with a Ge(Li) spectrometer. The measured energy separations are 50 ± 5 keV for the 15O doublet and 28.5 ± 3 keV for the 15N doublet. The difference between the 5.24-MeV gamma ray from 15O and the 5.27-MeV gamma ray from 15N is 29 ± 1 keV. From Doppler-shift and broadening measurements of the energies of the gamma rays from the T(16O, αγ)15N and 16O(3He, αγ)15O reactions, information on the mean lifetimes of the states was obtained. The mean lifetimes of the 5.30-and 5.27-MeV states of 15N are 4.3 ± 1.8 × 10−14 sec and > 10−12 sec respectively. The mean lifetimes of the 5.19- and 5.24-MeV states of 15O are < 3 × 10−13 sec and > 10−12 sec respectively.

Lifetime of the 8543 keV (6+) State of 28Si

1975 ◽  
Vol 53 (16) ◽  
pp. 1505-1506 ◽  
Author(s):  
W. R. Dixon ◽  
R. S. Storey ◽  
A. L. Carter ◽  
H. L. Pai
Keyword(s):  
Doppler Shift ◽  
Mean Lifetime ◽  
The Mean ◽  
Good Agreement

The 25Mg(α,nγ)28Si reaction has been used to populate the 8543 keV, 6+ state of 28Si and the mean lifetime has been determined from the attenuated Doppler shift of the 8543 → 4617, 6+ → 4+ transition. The result is 19 ± 8 fs, in good agreement with results from the (p,γ) reaction but not with an earlier measurement using the (α,nγ) reaction.

Energies of Some 25Al Levels from the 24Mg(p,γ)25Al Reaction and the Coulomb-Energy Differences of Analog Rotational Bands

1971 ◽  
Vol 49 (4) ◽  
pp. 402-406 ◽  
Author(s):  
F. Everling ◽  
G. L. Morgan ◽  
D. W. Miller ◽  
L. W. Seagondollar ◽  
P. W. Tillman Jr.
Keyword(s):  
Gamma Rays ◽  
Ground State ◽  
Mass Number ◽  
Resonance Energy ◽  
Coulomb Energy ◽  
Q Value ◽  
Ground State Band ◽  
Excitation Energies ◽  
Rotational Bands ◽  
State Band

Gamma rays from the 24Mg(p, γ)25Al reaction at the 1201 and 1485 keV resonances were measured with a 20 cm3 Ge(Li) detector. Excitation energies obtained for known levels in 25Al are (in keV): 1612.5 ± 0.5, 1789.6 ± 1.3, 3424.3 ± 0.6, and 3696.3 ± 1.1. By using the known 1201.4 ± 1.0 keV resonance energy, a more precise Q value of 2271.4 ± 1.2 keV is obtained, 16 keV lower than the previous value which had a 6 keV uncertainty.A brief discussion of the Coulomb-energy differences of 25Al and 25Mg analog rotational bands in relation to the 24Mg ground-state band is given and compared with the situation at mass number A = 21.

Self-interstitial Diffusion in α-Zirconium

2001 ◽  
Vol 677 ◽  
Author(s):  
W.J. Zhu ◽  
C.H. Woo
Keyword(s):  
Ground State ◽  
Diffusion Processes ◽  
Many Body ◽  
Interstitial Diffusion ◽  
One Dimensional ◽  
Mean Lifetime ◽  
Migration Mechanism ◽  
Out Of Plane ◽  
On Line ◽  
The Mean

ABSTRACTSelf-interstitial Diffusion in α-Zirconium-Zr is studied using Molecular Dynamic (MD) and molecular static (MS) simulation using Ackland's many-body inter-atomic potential. The basal crowdion configuration is found to be the ground state. The diffusion process in Zr is complex. Four types of diffusion jumps can be identified, two in-plane and two out-of plane. The in-plane migration mechanism is dominated by one-dimensional crowdion motion along the [1120] directions, interrupted by occasional out-of-plane and on-line or off-line jumps. The mean lifetime before rotation of the crowdion is reported as a function of temperature. The activation energies for the diffusion processes are obtained. The diffusional anisotropy factor Dc/Da is also obtained, and compares well with experiment results.

GAMMA RAYS FROM THE DISINTEGRATION OF BORON BY SLOW NEUTRONS

1948 ◽  
Vol 26a (6) ◽  
pp. 366-378 ◽  
Author(s):  
B. Rose
Keyword(s):  
Gamma Rays ◽  
Ground State ◽  
Proportional Counter ◽  
Boron Trifluoride ◽  
Slow Neutron ◽  
Γ Radiation ◽  
Geiger Muller Counter ◽  
Γ Ray ◽  
Α Particles ◽  
Slow Neutrons

The slow neutron disintegration of B10 yields two groups of α-particles, corresponding to the production of Li7 in either the ground state or an excited state. The γ-radiation accompanying the de-excitation of the excited nucleus was studied. Boron in the form of boron trifluoride in a proportional counter was irradiated with slow neutrons from a Ra–α–Be source. Coincidences were counted between α-particle pulses in the proportional counter and γ-ray pulses in an adjacent Geiger–Müller counter. The ratio of the α–γ coincidence rate to, the α-rate gave the product of the efficiency of the Geiger–Müller counter and the number of quanta emitted per boron disintegration. The absorption coefficient of the γ-radiation in lead was measured, and, by comparison with the absorption coefficients for the γ-radiation from Cu64 and Au198, the energy was found to be 0.48 ± 0.015 Mev. The quantum efficiency of the Geiger–Müller counter for radiation of this energy was determined by calibration with standard sources of Co60 and thorium active deposit. Hence the number of quanta per boron disintegration was found to be 0.90 ± 0.08, in satisfactory agreement with the value to be expected from the relative abundance of the α-particle groups from this reaction.

RADIOACTIVE DECAY OF W188

1962 ◽  
Vol 40 (6) ◽  
pp. 677-686 ◽  
Author(s):  
J. C. Roy
Keyword(s):  
Excited State ◽  
Gamma Rays ◽  
Ground State ◽  
Half Life ◽  
Decay Scheme ◽  
Radioactive Decay ◽  
Beta Transition ◽  
Upper Limit ◽  
Gamma Radiations

The half-life of W188 has been measured to be 69.4 ± 0.5 days. The gamma radiations emitted in the decay of W188 have been studied with an NaI scintillation spectrometer, and the beta radiations by absorption in aluminum. Three gamma rays with energies of 0.290 ± 0.005, 0.227 ± 0.005, and 0.063 ± 0.005 Mev were observed. The intensities of these gamma rays were measured relative to those gamma rays from the daughter activity Re188. The W188 gamma intensities thus deduced are respectively 0.002, 0.001, and about 0.001 per disintegration. The 0.227 and 0.063 gamma rays are in coincidence. It logically follows from the gamma results that 99.3% of the beta radiations go to the ground state of Re188 with an energy of 0.36 ± 0.04 Mev (determined by Feather analysis), while about 0.4% go to an excited state at 0.290 Mev; an upper limit of 0.3% has been set for a beta transition to the 0.063 state. A decay scheme for W188 is proposed.

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