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.

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.

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.

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.

Determination of the mean lives of some excited states of33S through doppler-shift attenuation measurement

1969 ◽  
Vol 2 (12) ◽  
pp. 600-604 ◽  
Author(s):  
F. Brandolini ◽  
J. Benuzzi-Martins ◽  
R. A. Ricci ◽  
C. Signorini
Keyword(s):  
Excited States ◽  
Doppler Shift ◽  
Attenuation Measurement ◽  
Doppler Shift Attenuation ◽  
The Mean

scholarly journals Sources of Variability in the Response of Labeled Microspheres and B Cells during the Analysis by a Flow Cytometer

2021 ◽  
Vol 22 (15) ◽  
pp. 8256
Author(s):  
Adolfas K. Gaigalas ◽  
Yu-Zhong Zhang ◽  
Linhua Tian ◽  
Lili Wang
Keyword(s):  
B Cells ◽  
Laser Beam ◽  
Cross Section ◽  
Mean Fluorescence Intensity ◽  
Numerical Aperture ◽  
Flow Cytometer ◽  
Fluorescence Signal ◽  
Minor Importance ◽  
Reliable Measure ◽  
The Mean

A stochastic model of the flow cytometer measurement process was developed to assess the nature of the observed coefficient of variation (CV%) of the mean fluorescence intensity (MFI) from a population of labeled microspheres (beads). Several sources of variability were considered: the total number of labels on a bead, the path through the laser beam, the optical absorption cross-section, the quantum yield, the numerical aperture of the collection optics, and the photoelectron conversion efficiency of the photomultiplier (PMT) cathode. The variation in the number of labels on a bead had the largest effect on the CV% of the MFI of the bead population. The variation in the path of the bead through the laser beam was minimized using flat-top lasers. The variability in the average optical properties of the labels was of minor importance for beads with sufficiently large number of labels. The application of the bead results to the measured CV% of labeled B cells indicated that the measured CV% was a reliable measure of the variability of antibodies bound per cell. With some modifications, the model can be extended to multicolor flow cytometers and to the study of CV% from cells with low fluorescence signal.

scholarly journals Extension of Pin-Based Point-Wise Energy Slowing-Down Method for VHTR Fuel with Double Heterogeneity

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2179
Author(s):  
Tae-Young Han ◽  
Jin-Young Cho ◽  
Chang-Keun Jo ◽  
Hyun-Chul Lee
Keyword(s):  
Cross Sections ◽  
Cell Model ◽  
Unit Cell ◽  
Moderation Effect ◽  
Slowing Down ◽  
Matrix Layer ◽  
The Mean ◽  
Dancoff Factor ◽  
Double Heterogeneity ◽  
Very High

For the resonance treatment of a very high temperature reactors (VHTR) fuel with the double heterogeneity, an extension of the pin-based pointwise energy slowing-down method (PSM) was developed and implemented into DeCART. The proposed method, PSM-double heterogeneity (DH), has an improved spherical unit cell model with an explicit tri-structural isotropic (TRISO) model, a matrix layer, and a moderator for reflecting the moderation effect. The moderator volume was analytically derived using the relation of the Dancoff factor and the mean chord length. In the first step, the pointwise homogenized cross-sections for the compact was obtained after solving the slowing down equation for the spherical unit cell. Then, the shielded cross-section for the homogenized fuel compact was generated using the original PSM. The verification calculations were performed for the fuel pins with various packing fractions, compact sizes, TRISO sizes, and fuel temperatures. Additionally, two fuel block problems with very different sizes were examined and the depletion calculation was carried out for investigating the accuracy of the proposed method. They revealed that the PSM-DH has a good performance in the VHTR problems.

Doppler-Shift Attenuation Measurements of Lifetimes for (2s,1d)-Shell Nuclei Excited by Heavy-Ion Bombardment ofH2

1973 ◽  
Vol 7 (3) ◽  
pp. 1120-1132 ◽  
Author(s):  
E. K. Warburton ◽  
J. W. Olness ◽  
G. A. P. Engelbertink ◽  
T. K. Alexander
Keyword(s):  
Doppler Shift ◽  
Ion Bombardment ◽  
Heavy Ion ◽  
Doppler Shift Attenuation
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