Magnetic Dipole Gamma-Ray Strength Function in Deformed Nuclei, and Neutron-Capture Gamma Rays

1969 ◽  
Vol 23 (5) ◽  
pp. 244-246 ◽  
Author(s):  
C. S. Shapiro ◽  
G. T. Emery
Keyword(s):  
Magnetic Dipole ◽  
Gamma Rays ◽  
Neutron Capture ◽  
Gamma Ray ◽  
Strength Function ◽  
Deformed Nuclei

scholarly journals Partial and total thermal neutron capture cross sections for non-destructive assay and transmutation monitoring of 99Tc

2002 ◽  
Vol 90 (8) ◽  
Author(s):  
G. L. Molnár ◽  
T. Belgya ◽  
Zs. Révay ◽  
Syed M. Qaim
Keyword(s):  
Gamma Rays ◽  
Cross Sections ◽  
Neutron Capture ◽  
Gamma Ray ◽  
Cold Neutron ◽  
Production Cross ◽  
Radioactive Product ◽  
Non Destructive ◽  
Decay Gamma ◽  
Capture Cross Sections

SummaryAccurate partial gamma-ray production cross sections were determined for the prompt and radioactive product decay gamma rays following cold neutron capture in

Intensity anomaly in the (d,pγ) reaction

1970 ◽  
Vol 48 (6) ◽  
pp. 687-708 ◽  
Author(s):  
G. A. Bartholomew ◽  
I. Bergqvist ◽  
E. D. Earle ◽  
A. J. Ferguson
Keyword(s):  
Excitation Energy ◽  
Gamma Rays ◽  
Single Particle ◽  
Gamma Ray ◽  
Strength Function ◽  
Neutron Separation Energy ◽  
Separation Energy ◽  
Excitation Energies

The spectra of gamma rays detected in coincidence with protons from the (d,pγ) reaction in elements [Formula: see text] and [Formula: see text] have been measured in gross structure with a NaI detector. The region of excitation energies covered in the product nuclei was from 0.8 MeV to about the neutron separation energy, typically 7 MeV. The gamma-ray anomalous bump at about 5.5 MeV was found from regions near the separation energy with an intensity comparable to that previously observed in (n,γ) reactions. By gating techniques the decay of many contiguous intervals of excitation energy, populated in the reaction, was studied. From the results, a strength function for gamma rays between 0.8 and 7 MeV approximately was extracted for Au, where the bump is prominent, and for Ta where the bump is essentially absent. In the particular case of 206Pb(d,pγ)207Pb, the gamma-ray spectra are interpreted in terms of the decay of known single particle states. An interpretation of the intensity anomaly in terms of doorway states is discussed.

GAMMA‐RAY SPECTROSCOPY IN WELL LOGGING

Geophysics ◽  
1963 ◽  
Vol 28 (4) ◽  
pp. 617-632 ◽  
Author(s):  
Richard L. Caldwell ◽  
Willett F. Baldwin ◽  
James D. Bargainer ◽  
James E. Berry ◽  
George N. Salaita ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Neutron Capture ◽  
Gamma Ray ◽  
Salt Water ◽  
Pulse Height ◽  
Energy Calibration ◽  
Good Energy Resolution ◽  
Scintillation Crystal ◽  
Natural Gamma ◽  
Good Energy

Thermal neutron capture gamma rays have been observed in boreholes drilled in shales, sandstones, and limestones. A capsuled source of neutrons and a scintillation crystal detector, connected through 5,000 ft of logging cable to a transistorized, multichannel, pulse‐height analyzer, were used. Resolved peaks were identified on the basis of the known energies of expected gamma rays and results obtained in models where conditions of porosity, casing, and fluid were controlled. To properly interpret borehole spectral data a system with good energy resolution and an accurate means of energy calibration are necessary. This is accomplished by using hydrogen and iron to give prominent gamma‐ray peaks at opposite ends of the energy range of interest. On field spectra, identification was made of gamma rays from chlorine, silicon, calcium, hydrogen, and iron. On the basis of chlorine gamma rays, salt water can be differentiated from oil or fresh water. Gamma rays from iron casing are an undesirable background and reduce the sensitivity of the method compared to that possible in an uncased hole. Two examples of natural gamma‐ray spectra show well resolved lines from uranium‐radium and thorium.

A STUDY OF THE GAMMA RADIATION FOLLOWING NEUTRON CAPTURE IN COPPER

1967 ◽  
Vol 45 (7) ◽  
pp. 2395-2408 ◽  
Author(s):  
A. H. Colenbrander ◽  
T. J. Kennett
Keyword(s):  
Gamma Radiation ◽  
Gamma Rays ◽  
Neutron Capture ◽  
Gamma Ray ◽  
Copper Target ◽  
Coincidence Measurements

The neutron capture gamma-ray spectrum for a natural copper target has been investigated using a Ge(Li) spectrometer. A total of 146 gamma rays were observed, of which about half have been isotopically assigned. Assignment was achieved through the use of coincidence measurements and (d, p) results. The neutron separation energies were found to be 7 914(3) and 7 063(3) keV for 64Cu and 66Cu respectively. The 66Cu gamma-ray transition to low-lying states exhibit exceptionally large radiation widths in a manner similar to the corresponding anomaly in 64Cu.

scholarly journals Gamma-Ray Lines from Solar Flares

1975 ◽  
Vol 68 ◽  
pp. 363-383 ◽  
Author(s):  
R. Ramaty ◽  
R. E. Lingenfelter
Keyword(s):  
Gamma Rays ◽  
Solar Flares ◽  
Neutron Capture ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
The Other ◽  
Line Production ◽  
Absolute Intensities ◽  
Flare Region ◽  
Accelerated Particles

We have treated in detail the theory of gamma-ray line production in solar flares. The strongest line, both predicted theoretically and detected observationally at 2.2 MeV, is due to neutron capture by protons in the photosphere. The neutrons are produced in nuclear reactions of flare accelerated particles which also produce positrons and prompt nuclear gamma rays. From the comparison of the observed and calculated intensities of the lines at 4.4 or 6.1 MeV to that of the 2.2 MeV line it is possible to deduce the spectrum of accelerated nuclei in the flare region; and from the absolute intensities of these lines it is possible to obtain the total number of accelerated nuclei at the Sun. The study of the 2.2 MeV line also gives information on the amount of He3 in the photosphere. The study of the line at 0.51 MeV resulting from positron annihilation complements the data obtained from the other lines; in addition it gives information on the temperature and density in the annihilation region and on the anisotropy of the accelerated electron beam which produces continuum gamma rays at energies greater than about 1 MeV.

scholarly journals Improved STEREO simulation with a new gamma ray spectrum of excited gadolinium isotopes using FIFRELIN

2019 ◽  
Vol 55 (10) ◽  
Author(s):  
H. Almazán ◽  
L. Bernard ◽  
A. Blanchet ◽  
A. Bonhomme ◽  
C. Buck ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Cross Sections ◽  
Neutron Capture ◽  
Gamma Ray ◽  
Detection Efficiency ◽  
Liquid Scintillator ◽  
Calibration Source ◽  
Active Volume ◽  
Capture Event ◽  
Excited Nuclei

Abstract. The STEREO experiment measures the electron antineutrino spectrum emitted in a research reactor using the inverse beta decay reaction on H nuclei in a gadolinium loaded liquid scintillator. The detection is based on a signal coincidence of a prompt positron and a delayed neutron capture event. The simulated response of the neutron capture on gadolinium is crucial for the comparison with data, in particular in the case of the detection efficiency. Among all stable isotopes, 155Gd and 157Gd have the highest cross sections for thermal neutron capture. The excited nuclei after the neutron capture emit gamma rays with a total energy of about 8MeV. The complex level schemes of 156Gd and 158Gd are a challenge for the modeling and prediction of the deexcitation spectrum, especially for compact detectors where gamma rays can escape the active volume. With a new description of the Gd (n,$ \gamma$γ) cascades obtained using the FIFRELIN code, the agreement between simulation and measurements with a neutron calibration source was significantly improved in the STEREO experiment. A database of ten millions of deexcitation cascades for each isotope has been generated and is now available for the user.

Fast Neutron Capture in Tl, Hg, Au, and Ta and Gamma Ray Strength Functions

1974 ◽  
Vol 52 (11) ◽  
pp. 989-998 ◽  
Author(s):  
E. D. Earle ◽  
M. A. Lone ◽  
G. A. Bartholomew ◽  
W. J. McDonald ◽  
K. H. Bray ◽  
...  
Keyword(s):  
Neutron Capture ◽  
Gamma Ray ◽  
Strength Function ◽  
Detector Response ◽  
Strong Decrease ◽  
Fitting Method ◽  
Spectral Distributions ◽  
Γ Ray ◽  
Strength Functions ◽  
Spectrum Fitting

Gamma ray spectra following the capture of 0.7, 1.7, and 2.6 MeV neutrons in Tl and Hg, of 0.7 and 2.6 MeV neutrons in Ta, and of 2.6 MeV neutrons in Au were measured with a NaI detector. The spectral distributions were obtained by unfolding the detector response function, and γ-ray strength functions were deduced for Tl, Au, and Ta by a spectrum fitting method. The strength functions in Tl and Au, when compared with the Lorentzian predictions, show a strong decrease below ~5 MeV and in Tl there is a resonance-like structure at ~5.5 MeV. No such structure is found in the strength function for Ta. This behavior is qualitatively interpreted in terms of recent particle–hole calculations.

LOGGING OF DRILL HOLES BY THE NEUTRON, GAMMA METHOD, AND GAMMA RAY SCATTERING

Geophysics ◽  
1951 ◽  
Vol 16 (2) ◽  
pp. 260-276 ◽  
Author(s):  
Henry Faul ◽  
C. W. Tittle
Keyword(s):  
Gamma Radiation ◽  
Neutron Source ◽  
Gamma Rays ◽  
Hydrogen Content ◽  
Neutron Capture ◽  
Gamma Ray ◽  
Drilling Mud ◽  
Favorable Conditions ◽  
Drill Holes ◽  
Gamma Intensity

The intensity distribution of secondary gamma radiation resulting from neutron capture has been measured in simulated drill holes, of various types such as cased and uncased, empty and water‐filled. The intensity of neutron‐capture gamma rays depends on the hydrogen content of the rock. In a six‐inch well, it increases with hydrogen content at points within about 16 inches of the neutron source and decreases at more distant points. The absolute gamma intensity is greatly reduced when non‐hydrogenous gamma‐ray or neutron absorbers, e.g., lead or boron are introduced between logging probe and formation. The slope of logarithmic gamma ray intensity vs. distance remains virtually constant. It changes with the hydrogen content of the formation and offers a means of quantitatively estimating porosity behind casing despite extraneous absorption. The slope can be measured automatically in the well by two gamma detectors placed in a probe at fixed distances from a neutron source. Hydrogenous material between probe and rock increases the slope. Two or three inches of drilling mud seriously impair the sensitivity. Gamma radiation scattered by the walls of drill holes necessitates proper shielding for detectors used in (n, γ) logging with a radium‐beryllium source. A shielded detector is predominantly sensitive to the hard neutron‐capture gamma rays and tends to discriminate against the softer scattered radiation. The scattered intensity decreases with increasing bulk density of the formation. Under favorable conditions, continuous logs of formation density as a function of depth can be obtained.

scholarly journals Evaluation of gamma-ray strength function based on measured gamma-ray pulse-height spectra in time-of-flight neutron capture experiments

2020 ◽  
Vol 239 ◽  
pp. 17016
Author(s):  
Nobuyuki Iwamoto ◽  
Shoji Nakamura ◽  
Atsushi Kimura ◽  
Tatsuya Katabuchi ◽  
Gerard Rovira ◽  
...  
Keyword(s):  
Response Function ◽  
Neutron Capture ◽  
Evaluation Method ◽  
Gamma Ray ◽  
Strength Function ◽  
Pulse Height ◽  
Reaction Model ◽  
Simulation Code ◽  
Model Code ◽  
Continuum Region

In order to develop an evaluation method of gamma-ray strength function (GSF), neutron capture pulse-height (PH) spectrum of gold was employed, where it was measured with the NaI(Tl) spectrometer of AN-NRI installed at the Material and Life Science Experimental Facility in J-PARC. The neutron capture gamma-ray spectrum of gold was calculated using the nuclear reaction model code CCONE. In order to obtain the information on GSF from the measured data, a gamma-ray response function for the NaI(Tl) spectrometer was calculated by the Monte-Carlo particle-transport simulation code PHITS. As a result, the PH spectrum comparable with measured one was derived by applying the gamma-ray response function to the calculated gamma-ray spectrum. By evaluation with measured PH spectra, we obtained GSF which reasonably explains measured PH spectrum in the continuum region.

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