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-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.

Negative Parity Levels in 30Si

1974 ◽  
Vol 52 (16) ◽  
pp. 1485-1491 ◽  
Author(s):  
M. Wayne Greene ◽  
H. H. Grawe ◽  
J. A. Kuehner
Keyword(s):  
Gamma Ray ◽  
Negative Parity ◽  
Coincidence Measurement ◽  
Model Structure ◽  
Polarization Direction ◽  
Decay Branch ◽  
Mean Lifetime ◽  
Doppler Shift Attenuation ◽  
Γ Rays ◽  
The Mean

A polarization direction correlation measurement of γ rays from the 7.044 MeV level in 30Si results in Jπ = 5− for this level and implies a Jπ = 4− assignment for the level at 6.503 MeV. A particle gamma ray coincidence measurement establishes a new decay branch (15 ± 4%) for the 6.503 MeV level to the 5.485 MeV Jπ = 3− level. The Doppler shift attenuation method was used to measure the mean lifetime of the 7.044 MeV level as [Formula: see text]. A simple shell model structure for the low lying negative parity states is presented and shown to be consistent with experimental measurements.

Gamma-Ray Angular Distribution, Angular Correlation, Linear Polarization, and Doppler-Shift Attenuation Measurements in the 46Ti(α, nγ) 49Cr Reaction

1977 ◽  
Vol 43 (3) ◽  
pp. 741-754 ◽  
Author(s):  
Jirohta Kasagi ◽  
Shigeru Nakagawa ◽  
Norio Kishida ◽  
Yuichi Iritani ◽  
Hajime Ohnuma
Keyword(s):  
Angular Distribution ◽  
Angular Correlation ◽  
Linear Polarization ◽  
Doppler Shift ◽  
Gamma Ray ◽  
Doppler Shift Attenuation

LIFETIMES OF THE LOW-LYING LEVELS OF 20Ne

1965 ◽  
Vol 43 (1) ◽  
pp. 82-95 ◽  
Author(s):  
H. C. Evans ◽  
M. A. Eswaran ◽  
H. E. Gove ◽  
A. E. Litherland ◽  
C. Broude
Keyword(s):  
Doppler Shift ◽  
Gamma Ray ◽  
Doppler Shift Attenuation ◽  
Doppler Shift Attenuation Method

The lifetimes of the 1.63-, 4.25-, 4.97-, and 5.63-MeV levels in 20Ne have been measured by the Doppler shift attenuation method. The lifetimes in picoseconds are 1.23 ± 0.12, 0.134 ± 0.012, [Formula: see text], and 0.35 ± 0.075 respectively. The reduced widths in Weisskopf units for the 1.63-, 2.62-, 3.34-, and 4.00-MeV gamma-ray transitions, together with the gamma-ray multipolarities, are [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text].

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.

On Doppler-Shift Attenuation Measurements

1972 ◽  
Vol 50 (24) ◽  
pp. 3147-3151 ◽  
Author(s):  
K. B. Winterbon
Keyword(s):  
Cross Section ◽  
Doppler Shift ◽  
Heavy Ions ◽  
Mass Ratio ◽  
Slowing Down ◽  
Target Mass ◽  
Doppler Shift Attenuation ◽  
Low Energies ◽  
Effet Doppler ◽  
The Mean

An improved analysis of Doppler-shifted γ spectra is outlined. This analysis is exact within the Lindhard theory of slowing down of heavy ions in solids.With an approximate cross section applicable at low energies, the equations become independent of the energy, except as a scaling parameter, and depend only on the projectile–target mass ratio. A set of universal curves of the mean fractional shift F(τ) is calculated in this approximation for several values of the mass ratio.Une analyse améliorée de spectres γ déplacés par effet Doppler est esquissée. Cette analyse est conforme à la théorie de Lindhard sur le ralentissement des ions lourds dans les solides.

Gamma-ray induced Doppler shift attenuation after (n, γ) reactions in Si and Ti

1997 ◽  
Vol 385 (1) ◽  
pp. 100-107 ◽  
Author(s):  
T Kahn ◽  
T von Egidy ◽  
F.J Hartmann ◽  
J Ott ◽  
M Jentschel
Keyword(s):  
Doppler Shift ◽  
Gamma Ray ◽  
Doppler Shift Attenuation

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.

Heat flow and surface radioactivity in the Quirke Lake Syncline near Elliot Lake, Ontario, Canada

1968 ◽  
Vol 5 (6) ◽  
pp. 1417-1428 ◽  
Author(s):  
J. H. Sass ◽  
P. G. Killeen ◽  
E. D. Mustonen
Keyword(s):  
Heat Flow ◽  
Heat Production ◽  
Gamma Ray ◽  
Average Rate ◽  
Structural Effects ◽  
Gamma Ray Spectrometer ◽  
A Value ◽  
The Mean ◽  
Data Yield ◽  
Ore Zones

Heat flow was measured in seven diamond-drilled holes, ranging in depth from 300 to 900 m, in the Quirke Lake Syncline (82° 30′ W, 46° 30′ N, mean elevation 370 m), Values for individual holes vary from 1.20 to 1.40 with a mean of 1.32 ± 0.02 μcal/cm2s, and no systematic variation was detected within the 50 km2 area studied. Radiometric measurements with a portable, three-channel, gamma-ray spectrometer show a downward concentration (stratigraphically) of Th, U, and K within the lower part of the syncline, with mean concentrations of 12.7 ppm, 3.3 ppm, and 1.9%, respectively. These data yield an average rate of heat production of 4.5 heat generation units (1 hgu = 10−13 cal/cm3s). Taking account of the ore zones, the mean heat production from the syncline is about 6 hgu. Corrections for structural effects and heat production from the ore result in a value of 1.2 for the regional heat flow. This is within the range of other shield values, although somewhat higher than the average for the Canadian Shield. The high value is readily explained if the observed mean surface radioactivity persists to a depth of 7 to 10 km.

Sign in / Sign up

Export Citation Format

Share Document