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.

Transition rates in 29P

1970 ◽  
Vol 48 (22) ◽  
pp. 2683-2691 ◽  
Author(s):  
C. F. Monahan ◽  
H. C. Evans ◽  
J. H. Montague ◽  
W. R. Paulson ◽  
W. M. Zuk
Keyword(s):  
Excited States ◽  
Gamma Rays ◽  
Doppler Shift ◽  
Resonance Level ◽  
Transition Rates ◽  
Mixing Ratios ◽  
Doppler Shift Attenuation ◽  
The Mean ◽  
Doppler Shift Attenuation Method ◽  
Mean Lifetimes

Lifetimes of three of the low-lying excited states in 29P, populated in the 28Si(p,γ) reaction, have been determined using the Doppler shift attenuation method. The mean lifetimes of states at 4.085, 1.956, and 1.385 MeV were found to be 15 ± 4, 370 ± 80, and 200 ± 60 fs.Angular distribution measurements have also been performed on gamma rays resulting from the decay of the 4.085 MeV resonance level. The decay was found to go via states at 3.107 MeV (3%), 1.956 MeV (54%), and 1.385 MeV (43%). The spin of the resonance level was uniquely assigned as 7/2 and the multipole mixing ratios of the 2.129 and 1.385 MeV transitions as + 0.17 ± 0.05 and + 0.303 ± 0.050 respectively. The consequent transition rates indicate that the parity of the resonance level is positive.

LIFETIMES OF THE 16O 6.13-MeV LEVEL AND THE 17O 0.871-MeV LEVEL

1965 ◽  
Vol 43 (9) ◽  
pp. 1563-1573 ◽  
Author(s):  
T. K. Alexander ◽  
K. W. Allen
Keyword(s):  
Doppler Shift ◽  
Gamma Ray ◽  
Doppler Shift Attenuation ◽  
The Mean ◽  
Data Yield ◽  
Gamma Ray Detector ◽  
Mean Lifetimes

The mean lifetimes of the 0.871-MeV state of 17O(E2) and the 6.13-MeV state of 16O(E3) have been measured by a new recoil method using a Ge(Li) gamma-ray detector. The data yield mean lifetimes of (2.33 ± 0.27) × 10−10 and (2.5 ± 0.2) × 10−11 sec for the states in 17O and 16O respectively. The recoil method is generally applicable to the measurement of lifetimes greater than about 5 × 10−12 sec and provides a technique for a region of time where neither direct electronic timing nor Doppler-shift attenuation methods are accurate.

Gamma rays in the MeV region at balloon altitude

1968 ◽  
Vol 46 (10) ◽  
pp. S494-S497 ◽  
Author(s):  
K. Okudaira ◽  
Y. Hirasima
Keyword(s):  
Gamma Rays ◽  
Main Part ◽  
Counting Rate ◽  
Gamma Ray ◽  
Plastic Scintillator ◽  
Scintillation Counter ◽  
Lower Atmosphere ◽  
Upper Limit ◽  
Extraterrestrial Origin ◽  
The Difference

Gamma rays in the MeV region were observed from balloons at λ = 26 °N on September 29, 1966. A scintillation counter constructed with two NaI ⅓ in. × 2 in. [Formula: see text] crystals separated by 1 cm × 2 in. [Formula: see text] lead was used to measure the directional distribution of the gamma-ray flux. This counter was flown at an atmospheric depth of 14.2 g cm−2. As the response of each crystal of this counter depends on the direction of incidence of the gamma rays, an anisotropic distribution of gamma rays gives rise to a difference between the counting rates of two crystals. It was ascertained from the observation that albedo gamma rays from the lower atmosphere are predominant at this high altitude. The deviation from the calculated values of the difference in counting rate assuming only atmospheric gamma rays may be due to an extraterrestrial origin of part of the gamma-ray flux. For the measurement of the gamma-ray spectrum, a phoswich counter (1 in. × 1 in. [Formula: see text] NaI crystal surrounded by ¼-in.-thick plastic scintillator) was flown to 10 g cm−2. Though the main part of the gamma-ray flux is probably due to atmospheric gamma rays, an upper limit for the isotropic cosmic gamma-ray flux is deduced to be (1.25 ± 0.05) × 10−2 counts cm−2 s−1 sr−1 MeV−1 in the energy range 1.2–3.1 MeV.

scholarly journals Prompt fission gamma-ray emission spectral data for 239Pu(n,f) using fast directional neutrons from the LICORNE neutron source

2018 ◽  
Vol 169 ◽  
pp. 00018 ◽  
Author(s):  
L. Qi ◽  
J.N. Wilson ◽  
M. Lebois ◽  
A. Al-Adili ◽  
A. Chatillon ◽  
...  
Keyword(s):  
Neutron Source ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Average Energy ◽  
Fast Neutrons ◽  
Complementary Information ◽  
Total Energy Release ◽  
The Mean ◽  
Induced Fission ◽  
Prompt Fission

Prompt fission gamma-ray spectra (PFGS) have been measured for the 239Pu(n,f) reaction using fast neutrons at Ēn=1.81 MeV produced by the LICORNE directional neutron source. The setup makes use of LaBr3 scintillation detectors and PARIS phoswich detectors to measure the emitted prompt fission gamma rays (PFG). The mean multiplicity, average total energy release per fission and average energy of photons are extracted from the unfolded PFGS. These new measurements provide complementary information to other recent work on thermal neutron induced fission of 239Pu and spontaneous fission of 252Cf.

scholarly journals A Note on the Role of Mean Flows in Doppler-Shifted Frequencies

2013 ◽  
Vol 43 (2) ◽  
pp. 432-441 ◽  
Author(s):  
Theo Gerkema ◽  
Leo R. M. Maas ◽  
Hans van Haren
Keyword(s):  
Doppler Shift ◽  
Wave Dispersion ◽  
The Other ◽  
Mean Flow ◽  
Fixed Position ◽  
Doppler Shifts ◽  
The Mean ◽  
The Difference ◽  
The One

Abstract The purpose of this paper is to resolve a confusion that may arise from two quite distinct definitions of “Doppler shifts”: both are used in the oceanographic literature but they are sometimes conflated. One refers to the difference in frequencies measured by two observers, one at a fixed position and one moving with the mean flow—here referred to as “quasi-Doppler shifts.” The other definition is the one used in physics, where the frequency measured by an observer is compared to that of the source. In the latter sense, Doppler shifts occur only if the source and observer move with respect to each other; a steady mean flow alone cannot create a Doppler shift. This paper rehashes the classical theory to straighten out some misconceptions. It is also discussed how wave dispersion affects the classical relations and their application.

The isotope effect in the electronic structure factors of liquid NH3 and ND3

1995 ◽  
Vol 73 (11-12) ◽  
pp. 735-740 ◽  
Author(s):  
S. Takeda ◽  
P. A. Egelstaff
Keyword(s):  
Electronic Structure ◽  
Gamma Rays ◽  
Correlation Functions ◽  
Gamma Ray ◽  
Liquid Structure ◽  
Density Correlation ◽  
Structure Factors ◽  
Radioisotope Source ◽  
The Difference ◽  
Absorption Technique

Gamma rays from a radioisotope source, 241Am, were scattered from samples of liquid light ammonia (NH3) and heavy ammonia (ND3) at temperatures of 294.5 and 284.5 K under their normal vapour pressures to determine the electronic liquid structure factors. In addition the densities of these samples were checked by the gamma ray absorption technique. From the difference between the total electronic structure factors of liquid NH3 and ND3, the difference of the r-space electronic correlation functions of the two liquids (at the same temperature) was evaluated. The observable difference is due (mainly) to quantum effects in the intermolecular electron-density correlation functions of liquid ammonia, which will be discussed.

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.

THE DECAY OF Os191 AND Os193

1958 ◽  
Vol 36 (10) ◽  
pp. 1409-1429 ◽  
Author(s):  
S. V. Nablo ◽  
M. W. Johns ◽  
R. H. Goodman ◽  
A. Artna
Keyword(s):  
Excited States ◽  
Gamma Rays ◽  
Cross Sections ◽  
Decay Scheme ◽  
Internal Conversion ◽  
Gamma Ray ◽  
Internal Conversion Coefficients ◽  
Gamma Coincidence ◽  
Conversion Coefficients ◽  
Activation Cross Sections

The beta- and gamma-ray spectra of Os191 and Os193 have been studied with a magnetic beta-ray spectrometer, scintillation spectrometers, and coincidence circuits. The 14-hour isomer of Os191 decays via a 0.0742-Mev (M3) transition. Gamma rays of energy 0.0418 (100%, E3), 0.0809 (1%, M1 + E2), 0.1287 (100%, M1 + E2), and 0.1858 (0.1%) Mev have been found to be associated with the 14.6 ± 0.3 day decay of Os191 and an extension of the accepted decay scheme proposed. The following 19 transitions have been associated with the 31.5 ± 0.5 hour decay of Os193: 0.0730 (14%), 0.1068 (~1%), 0.1393 (10%), 0.180 (0.3%), 0.196 (0.1%), 0.243 (~0.2%), 0.2485 (0.3%), 0.2514 (0.4%), 0.278 (0.6%), 0.2810 (1.6%), 0.2885 (0.3%), 0.2994 (0.4%), 0.314 (0.3%), 0.3218 (1.7%), 0.3620 (0.6%), 0.3878 (1.6%), 0.4604 (4.1%), 0.4857 (0.3%), and 0.5585 (2.2%). The internal conversion coefficients for all the stronger transitions suggest that they are M1 + E2 in character. The decay energy of Os193 is 1.132 ± 0.005 Mev. Fermi analyses and beta–gamma coincidence experiments have established excited states of Ir193 at 0.073, 0.139, 0.281, 0.362, 0.460, and 0.559 Mev above the ground state. Six otherwise unclassified weak gamma rays can be accommodated if levels at 0.247, 0.315, and 0.613 Mev are included in the decay scheme.The activation cross sections of Os184 and Os190 are (2.2 ± 0.5) × 103and 5.3 ± 2 barns respectively, relative to Seren's value of 1.6 ± 0.4 barns for Os192.

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.

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.

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