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.

scholarly journals How do we infer shell effects at high-excitation energies? A new spectroscopic probe to search for magic numbers

2019 ◽  
Vol 223 ◽  
pp. 01045 ◽  
Author(s):  
Cebo Ngwetsheni ◽  
José Nicolás Orce
Keyword(s):  
Gamma Ray ◽  
Strength Function ◽  
Dipole Polarizability ◽  
Magic Numbers ◽  
Data Sets ◽  
High Excitation ◽  
Excitation Energies ◽  
Long Range Correlations ◽  
Shell Effects ◽  
Spectroscopic Probe

The nuclear dipole polarizability is mainly governed by the dynamics of the giant dipole resonance and, assuming validity of the brink-Axel hypothesis, has been investigated along with the effects of the low-energy enhancement of the photon strength function for nuclides in medium- and heavy-mass nuclei. Cubic-polynomial fitsto both data sets extrapolated down to a gamma-ray energy of 0.1 MeV show a significantreduction of the nuclear dipole polarizability for semi-magic nuclei, with magic numbers N =28, 50 and 82, which supports shell effects at high-excitation energies in the the quasi-continuum region. This work assigns σ-2 values as sensitive measures of long-range correlations of the nuclear force and provides a new spectroscopic probe to search for “old” and “new” magic numbers at high-excitation energies.

An investigation of the 35Cl(n,γ)36Cl reaction

1981 ◽  
Vol 59 (1) ◽  
pp. 93-108 ◽  
Author(s):  
T. J. Kennett ◽  
M. A. Islam ◽  
W. V. Prestwich
Keyword(s):  
Gamma Rays ◽  
Decay Scheme ◽  
Gamma Ray ◽  
Average Energy ◽  
High Energy ◽  
Neutron Separation Energy ◽  
Transition Energies ◽  
New Findings ◽  
Deconvolution Techniques ◽  
Average Uncertainty

A detailed study of the neutron-capture gamma-ray spectrum for chlorine, above an energy of 1.6 MeV, has revealed a total of 234 transitions with intensity greater than 0.04%. Consistency tests indicate that the average energy uncertainty for the entire set of gamma rays is 0.1 keV. Data reduction was accomplished by invoking spectral deconvolution techniques with the result that many previously reported transitions were found to be multiplets. A decay scheme was derived by making use of both these new findings and the high energy precision attained for the transition energies. The proposed decay scheme accounts for more than 98% of the observed intensity and the energy of the levels included were found to have an average uncertainty of 0.08 keV. Based upon an error-free 15N neutron separation energy of 10 833.30 keV, the Q values for 35Cl(n,γ)36Cl and 37Cl(n,γ)38Cl were found to be 8579.82 (2) and 6107.85 (10) keV, respectively.

A STUDY OF THE GAMMA RADIATION FOLLOWING THERMAL NEUTRON CAPTURE BY SILICON

1967 ◽  
Vol 45 (5) ◽  
pp. 1871-1884 ◽  
Author(s):  
H. Lycklama ◽  
L. B. Hughes ◽  
T. J. Kennett
Keyword(s):  
Gamma Radiation ◽  
Thermal Neutron ◽  
Single Particle ◽  
Neutron Capture ◽  
Decay Scheme ◽  
Time Correlation ◽  
Neutron Separation Energy ◽  
Thermal Neutron Capture ◽  
Separation Energy

A study of the gamma radiation following thermal neutron capture by natural silicon has been conducted. Precise energy measurements were obtained using a Ge(Li) counter and a decay scheme was constructed using the time correlation results obtained with a Ge(Li)–NaI(Tl) spectrometer. The neutron separation energy was found to be 8 474 ± 1 keV for 29Si. An examination of the reduced radiation widths revealed that, while E1 and E2 radiation agreed well with the single-particle estimate, the M1 strength was hindered by a factor of from 10 to 100.

THE LEVEL STRUCTURE OF 104Rh OBSERVED IN THERMAL NEUTRON CAPTURE

1966 ◽  
Vol 44 (9) ◽  
pp. 2041-2051 ◽  
Author(s):  
L. B. Hughes ◽  
T. J. Kennett ◽  
W. V. Prestwich
Keyword(s):  
Energy Range ◽  
Thermal Neutron ◽  
Neutron Capture ◽  
Gamma Ray ◽  
Level Structure ◽  
Neutron Separation Energy ◽  
Thermal Neutron Capture ◽  
Separation Energy

The capture gamma-ray spectrum of the reaction 103Rh(n, γ)104Rh has been studied using a Ge(Li) spectrometer. The energy range covered was from 3 600 to 7 500 keV with an average resolution of 12 keV. A total of 100 transitions were observed and the neutron separation energy was found to be 6 999 ± 3 keV.

Study of the reaction 35Cl(n,γ)36Cl

1970 ◽  
Vol 48 (10) ◽  
pp. 1130-1139 ◽  
Author(s):  
L. B. Hughes ◽  
T. J. Kennett
Keyword(s):  
Gamma Radiation ◽  
Gamma Ray ◽  
Neutron Separation Energy ◽  
Transition Rates ◽  
Separation Energy ◽  
Average Precision ◽  
The Absolute ◽  
Reaction 35Cl

The gamma radiation from the 35Cl(n,γ)36Cl reaction has been studied using a Ge(Li) spectrometer. A total of 130 gamma-ray transitions was observed with an average precision of 2 keV. The neutron separation energy was found to be 8580.6 ± 1.0 keV. An examination of the partial radiative widths revealed that the ratio of E1 to M1 radiation agreed well with the ratio obtained from other measurements of E1 and M1 transition rates but the absolute values were enhanced by a factor of 10.

Study of Low-Lying Levels in 37Ar

1972 ◽  
Vol 50 (11) ◽  
pp. 1182-1194 ◽  
Author(s):  
P. Taras ◽  
A. Turcotte ◽  
R. Vaillancourt
Keyword(s):  
Angular Distribution ◽  
Gamma Rays ◽  
Linear Polarization ◽  
Ground State ◽  
Solar Neutrino ◽  
Gamma Ray ◽  
Capture Rate ◽  
Mixing Ratio ◽  
Excitation Energies ◽  
Decay Gamma

The properties of the first five excited levels in 37Ar were investigated via the 37Cl(p,n)37Ar reaction at Ep = 3.98, 4.17, 4.38, and 4.81 MeV and via the 34S(α,n)37Ar reaction at Eα = 8.00, 8.50, and 8.60 MeV. The following excitation energies were obtained: Ex = 1409.7 ± 0.4, 1611.5 ± 0.4, 2217.8 ± 0.8, 2491.4 ± 0.8, and 2797.0 ± 0.8 keV. These levels were found to decay almost entirely to the ground state. The angular distribution and the linear polarization of the decay gamma rays of these levels were measured. From these measurements definite spin–parity assignments as well as values of the mixing ratio of the ground state gamma-ray transitions were obtained. These are: Ex(Jπ, δ) = 1612 ([Formula: see text], +0.11 ± 0.02), 2218 ([Formula: see text], 0.0 ± 0.02), 2491 ([Formula: see text]), and 2797 ([Formula: see text], −0.16 ± 0.03 or +8.0 ± 1.5, the value of −0.16 being more probable). The measurements were also consistent with a spin of [Formula: see text] for the 1410 keV level. The results are compared with a recent shell-model calculation and are discussed in the context of the solar neutrino capture rate in 37Cl.

On the possible gamma-ray source in Cygnus

1967 ◽  
Vol 31 ◽  
pp. 469-471
Author(s):  
J. G. Duthie ◽  
M. P. Savedoff ◽  
R. Cobb
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Right Ascension

A source of gamma rays has been found at right ascension 20h15m, declination +35°, with an uncertainty of 6° in each coordinate. Its flux is (1·5 ± 0·8) x 10-4photons cm-2sec-1at 100 MeV. Possible identifications are reviewed, but no conclusion is reached. The mechanism producing the radiation is also uncertain.

Solar Flare Energetic Neutral Emission Measurements in the Project Coronas-I

1994 ◽  
Vol 144 ◽  
pp. 635-639
Author(s):  
J. Baláž ◽  
A. V. Dmitriev ◽  
M. A. Kovalevskaya ◽  
K. Kudela ◽  
S. N. Kuznetsov ◽  
...  
Keyword(s):  
Solar Flare ◽  
Energy Range ◽  
Gamma Rays ◽  
Pulse Shape ◽  
Gamma Ray ◽  
Pulse Shape Discrimination ◽  
Shape Discrimination ◽  
Solar Neutron ◽  
Low Altitude

AbstractThe experiment SONG (SOlar Neutron and Gamma rays) for the low altitude satellite CORONAS-I is described. The instrument is capable to provide gamma-ray line and continuum detection in the energy range 0.1 – 100 MeV as well as detection of neutrons with energies above 30 MeV. As a by-product, the electrons in the range 11 – 108 MeV will be measured too. The pulse shape discrimination technique (PSD) is used.

scholarly journals On a Possible Origin of the Gamma-ray Excess around the Galactic Center

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1432
Author(s):  
Dmitry O. Chernyshov ◽  
Andrei E. Egorov ◽  
Vladimir A. Dogiel ◽  
Alexei V. Ivlev
Keyword(s):  
Dark Matter ◽  
Gamma Rays ◽  
Molecular Clouds ◽  
Alternative Explanation ◽  
Gamma Ray ◽  
Galactic Center ◽  
The Self ◽  
Large Area ◽  
Mhd Turbulence ◽  
The Standard Model

Recent observations of gamma rays with the Fermi Large Area Telescope (LAT) in the direction of the inner galaxy revealed a mysterious excess of GeV. Its intensity is significantly above predictions of the standard model of cosmic rays (CRs) generation and propagation with a peak in the spectrum around a few GeV. Popular interpretations of this excess are that it is due to either spherically distributed annihilating dark matter (DM) or an abnormal population of millisecond pulsars. We suggest an alternative explanation of the excess through the CR interactions with molecular clouds in the Galactic Center (GC) region. We assumed that the excess could be imitated by the emission of molecular clouds with depleted density of CRs with energies below ∼10 GeV inside. A novelty of our work is in detailed elaboration of the depletion mechanism of CRs with the mentioned energies through the “barrier” near the cloud edge formed by the self-excited MHD turbulence. This depletion of CRs inside the clouds may be a reason for the deficit of gamma rays from the Central Molecular Zone (CMZ) at energies below a few GeV. This in turn changes the ratio between various emission components at those energies and may potentially absorb the GeV excess by a simple renormalization of key components.

Sign in / Sign up

Export Citation Format

Share Document