scholarly journals Femtosecond pumping of nuclear isomeric states by the Coulomb collision of ions with quivering electrons

2020 ◽  
Author(s):  
Changbo Fu ◽  
Jie Feng ◽  
Wenzhao Wang ◽  
Liming Chen ◽  
Junhao Tan ◽  
...  
Keyword(s):  
Cross Sections ◽  
High Efficiency ◽  
Gamma Ray ◽  
Coulomb Excitation ◽  
Laser System ◽  
Reaction Cross ◽  
Efficient Production ◽  
Coulomb Collision ◽  
Nuclear Batteries ◽  
Isomeric States

Abstract Efficient production of metastable quantum states of nuclei (isomers) is critical for exotic applica- tions, like nuclear clocks, nuclear batteries, clean nuclear energy, and nuclear gamma-ray lasers[1–6]. However, due to low reaction cross sections and quick decay, it is extremely difficult to acquire sig- nificant amount of isomers with short lifetimes via traditional accelerators or reactors. Here, we present femtosecond pumping of nuclear isomeric states by the Coulomb excitation of ions with the quivering electrons induced by laser fields for the first time. Nuclear isomers populated on the second excited state of 83Kr, are generated with a rate of 3.84 × 10^17 per second from a table-top hundreds-TW laser system. This high efficiency of isomer production can be explained by Coulomb collision[7] of ions with the quivering electrons during the laser-cluster interactions at nearly solid densities.

scholarly journals On the Experimental Investigation of the Angular Distributions in the Reaction 112Cd(p,γ)113In

2019 ◽  
Vol 26 ◽  
pp. 188
Author(s):  
A. Zyriliou ◽  
A. Khaliel ◽  
T. J. Mertzimekis
Keyword(s):  
Cross Sections ◽  
Nuclear Physics ◽  
Gamma Ray ◽  
Reaction Cross ◽  
Angular Distributions ◽  
Special Focus ◽  
Tandem Accelerator ◽  
Section Data ◽  
Hpge Detectors ◽  
Low Energies

Some of the mid–weight nuclei lie in the region of the isotopic chart where the astrophysical p-process has a prominent role in the nucleosynthetic scenarios. Experimentally deduced reaction cross section data can provide stringent tests for the astrophysical models, especially at low energies. In this framework, the reaction 112Cd(p,γ)113In has been studied experimentally at four proton beam energies 2.8 ≤ Ep≤ 3.4 MeV, partly inside the astrophysically interesting Gamow window. Proton beams were provided by the 5.5 MV T11 Van de Graaff Tandem Accelerator of the Institute of Nuclear Physics of the National Center for Scientific Research (NCSR) “Demokritos”. In–beam spectroscopy was carried out with an array of four HPGe detectors sitting on a rotating table. In total, eight (8) different angles were used to record gamma–ray spectra. Special focus was given on constructing the angular distribution of each gamma–ray feeding the ground state of 113In directly, so as to determine the reaction cross sections from the in–beam data, exclusively. The resulting cross sections were compared to Hauser–Feshbach calculations using the code TALYS v1.9.

scholarly journals 14.8 MeV Neutron Activation Cross Section Measurements for Ge Isotopes

2009 ◽  
Vol 1 (2) ◽  
pp. 173-181 ◽  
Author(s):  
M. M. Haque ◽  
M. T. Islam ◽  
M. A. Hafiz ◽  
R. U. Miah ◽  
M. S. Uddin
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Gamma Ray ◽  
Reaction Cross ◽  
Activation Cross Section ◽  
Section Data ◽  
Gamma Ray Spectroscopy ◽  
24Na Reaction ◽  
The Cross ◽  
Good Agreement

The cross sections of Ge isotopes were measured with the activation method at 14.8 MeV neutron energy. The quasi-monoenergetic neutron beams were produced via the 3H(d,n)4He reaction at the 150 kV J-25 neutron generator of INST, AERE. The characteristics γ-lines of the product nuclei were measured with a closed end coaxial 17.5 cm2 high purity germanium (HPGe) detector gamma ray spectroscopy. The cross sections were determined with reference to the known 27Al(n,α)24Na reaction. Cross section data are presented for 72Ge(n,p)72Ga, 74Ge(n,α)71mZn and 76Ge(n,2n)75m+gGe reactions. The cross section values obtained for the above reactions were 24.78±1.75 mb, 1.69±0.11 mb and 860±50 mb, respectively. The results obtained were compared with the values reported in literature as well as theoretical calculation performed by the statistical code SINCROS-II. The experimental data were found fairly in good agreement with the calculated and literature data.  Keywords: Activation cross section; Neutron induced reaction; Gamma-ray spectroscopy; 14.8 MeV. © 2009 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v1i2.1532  

scholarly journals Study of the photon strength functions and level density in the gamma decay of the n + 234U reaction

2019 ◽  
Vol 211 ◽  
pp. 02002 ◽  
Author(s):  
J. Moreno-Soto ◽  
E Berthoumieux ◽  
E Dupont ◽  
F Gunsing ◽  
O Serot ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Cross Sections ◽  
High Efficiency ◽  
Level Density ◽  
Reaction Cross ◽  
Level Densities ◽  
Strength Functions ◽  
Gamma Decay ◽  
Reaction Cross Sections ◽  
Nuclear Applications

The accurate calculations of neutron-induced reaction cross sections are relevant for many nuclear applications. The photon strength functions and nuclear level densities are essential inputs for such calculations. These quantities for 235U are studied using the measurement of the gamma de-excitation cascades in radiative capture on 234U with the Total Absorption Calorimeter at n_TOF at CERN. This segmented 4π gamma calorimeter is designed to detect gamma rays emitted from the nucleus with high efficiency. This experiment provides information on gamma multiplicity and gamma spectra that can be compared with numerical simulations. The code DICEBOXC is used to simulate the gamma cascades while GEANT4 is used for the simulation of the interaction of these gammas with the TAC materials. Available models and their parameters are being tested using the present data. Some preliminary results of this ongoing study are presented and discussed.

Analysis of the excitation function of alpha-particle-induced reactions on natural silver

1996 ◽  
Vol 74 (9-10) ◽  
pp. 618-625 ◽  
Author(s):  
H. B. Patel ◽  
M. S. Gadkari ◽  
Bhruna Dave ◽  
N. L. Singh ◽  
S. Mukherjee
Keyword(s):  
Cross Sections ◽  
Gamma Ray ◽  
Residual Nucleus ◽  
Reaction Cross ◽  
Activation Technique ◽  
Individual Reaction ◽  
Reaction Channels ◽  
Stacked Foil Activation Technique ◽  
The Individual ◽  
Reaction Cross Sections

Excitation functions of the reactions 107Ag[(α, n); (α, 2n); (α, αn); (α, α2n)] and,109Ag[(α, 2n); (α, 3n); (α, 4n); (α, α3n); (α, α4n)] were investigated up to 70 MeV by the stacked foil activation technique and Ge(Li) gamma-ray spectroscopy method. Since the natural silver used as the target has two odd mass stable isotopes of abundance 51.83% (107Ag) and 48.17% (109Ag), their activation in some cases gives the same residual nucleus through different reaction channels, but with very different Q values. In such cases, the individual reaction cross sections are separated with the help of the ratio of theoretical cross sections. The experimental cross sections were compared with the predictions of a pre-equilibrium hybrid model. The (α, xn) reactions are fairly well reproduced with initial exciton number n0 = 4(4p0h), whereas (α, αxn) reactions are underestimated in magnitude by a factor of five to six.

scholarly journals Cross Section Measurements in the 54Cr(p, ?)55Mn Reaction

1979 ◽  
Vol 32 (4) ◽  
pp. 335 ◽  
Author(s):  
R. J. Wilkinson ◽  
A S. R. Kennett ◽  
A Z. E. Switkowski ◽  
D. G. SargoodA and F. M. MannC
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Reaction Cross Section ◽  
Proton Energy ◽  
Gamma Ray ◽  
Reaction Cross ◽  
Model Calculations ◽  
Global Parameter ◽  
Dramatic Effect ◽  
Bombarding Energy

Cross sections for production of individual y rays in the 54Cr(p, y)55Mn reaction have been measured over the proton energy range 1�0-3�8 MeV. Gamma-ray yields are observed to fall by factors of between 5 and 10 at the crossing of the neutron threshold for a proton bombarding energy of 2�2 MeV. Statistical model calculations with global parameter sets successfully account for the dramatic effect of neutron competition on the (p, y) cross section, and at the same time correctly predict the 54Cr(p,n)54Mn reaction cross section.

scholarly journals Measurement of (n, xnγ) reaction Cross-sections on natural lead using in-beam gamma-Ray spectroscopy

2003 ◽  
Vol 18 (1) ◽  
pp. 22-30 ◽  
Author(s):  
Mila Pandurovic ◽  
Strahinja Lukic ◽  
Paule Baumann ◽  
Stpehane Hilaire ◽  
Jasmina Jeknic ◽  
...  
Keyword(s):  
Cross Sections ◽  
Nuclear Reactor ◽  
Gamma Ray ◽  
Nuclear Data ◽  
High Energy ◽  
Reaction Cross ◽  
Universal Method ◽  
Reactor Technology ◽  
Starting Point ◽  
Reaction Cross Sections

New concepts in nuclear reactor technology require precise neutron reaction data in the intermediate and high energy range. At present, experimental and evaluated nuclear data, particularly for (n, xn) reactions, are very scarce. Moreover, real discrepancies exist between different databases. The lack of experimental data is essentially due to the difficulty of measuring (n, xn) reactions. No universal method applicable to all isotopes exists. One of the possible methods is the in-beam y-ray spectroscopy and neutron time of flight technique on white neutron beams. In this way one actually directly measures (n, xny) reaction cross-sections. These serve as a starting point in the subsequent derivation of (n, xn) reaction cross-sections using nuclear models. This method was applied with a natural lead sample at me GELLNA white neutron beam facility in Geel, Belgium.

Fast modeling of gamma-gamma density measurementsvia gamma-ray point-kernel approximations

Geophysics ◽  
2019 ◽  
Vol 84 (2) ◽  
pp. D57-D72 ◽  
Author(s):  
Mathilde Luycx ◽  
Carlos Torres-Verdín
Keyword(s):  
Monte Carlo ◽  
Cross Sections ◽  
Gamma Ray ◽  
Forward Modeling ◽  
Reaction Cross ◽  
Second Order ◽  
Complex Geometries ◽  
First Order ◽  
Sensitivity Functions ◽  
Gamma Density

Forward-modeling algorithms based on flux sensitivity functions are commonly recognized as fast, reliable, and the most efficient way to implement inversion-based interpretation algorithms for borehole nuclear measurements. Second-order sensitivity functions enhance the accuracy of fast-forward-modeling algorithms in complex geometries: In the presence of standoff, density accuracy is improved up to 70% compared with first-order approximations. However, second-order sensitivity functions can only be generated with the Monte Carlo [Formula: see text]-Particle code for perturbations in bulk density, material composition, and reaction cross sections; therefore, their use is limited to gamma-gamma borehole density measurements. We have developed an alternative method to second-order approximations in complex 3D geometries. It is the first step toward future improvements to simulate borehole environmental effects across arbitrary well trajectories for nuclear measurements based on coupled neutron and gamma-ray transport. The gamma flux-difference (GFD) method quantifies gamma-ray flux perturbations using exponential point kernels and Rytov approximations. Gamma-ray point kernels are corrected for flux buildup and flux perturbations caused by radial heterogeneities, i.e., standoff. Correction coefficients are calculated by flux-fitting 1D radial sensitivity functions yielded by MCNP to the 1D exponential gamma-ray kernel; they depend on standoff and mud density, but they are negligibly affected by formation properties. The GFD method is benchmarked against Monte Carlo calculations. Compared with first-order approximations, it improves simulated density accuracy across regions of significant contrasting properties, up to [Formula: see text] with 3.18 cm (1.25 in) standoff and freshwater mud. The GFD method yields a maximum density error of [Formula: see text] across complex geometries and up to up to 4.45 cm (1.75 in) standoff, similar to that achieved by second-order forward modeling algorithms. Moreover, the principles behind GFD approximations can be adapted to measurements based on coupled neutron and gamma-ray transport.

scholarly journals A 4π γ-summing method for cross-section measurements of capture reactions

2020 ◽  
Vol 15 ◽  
pp. 111
Author(s):  
A. Spyrou ◽  
H.-W. Becker ◽  
A. Lagoyannis ◽  
S. Harissopulos ◽  
C. Rolfs
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Large Volume ◽  
Coulomb Barrier ◽  
Reaction Cross Section ◽  
High Efficiency ◽  
Reaction Cross ◽  
Capture Reaction ◽  
Stellar Nucleosynthesis ◽  
Reaction Cross Sections

Capture reaction cross sections at energies far below the Coulomb barrier are of major importance for the understanding of stellar nucleosynthesis. Since the cross sections of the majority of these reactions are very small, the use of high efficiency detectors is essential. In this work, a new method for capture reaction cross section measurements based on a large volume 4π NaI detector is presented.

Effect of nuclear surface diffuseness on Coulomb excitation and total nuclear reaction cross sections

2019 ◽  
Vol 992 ◽  
pp. 121620
Author(s):  
Monika Goyal ◽  
Rajiv Kumar ◽  
Pradeep Singh ◽  
Raj Kumar Seth ◽  
Rajesh Kharab
Keyword(s):  
Nuclear Reaction ◽  
Cross Sections ◽  
Coulomb Excitation ◽  
Reaction Cross ◽  
Nuclear Surface ◽  
Surface Diffuseness ◽  
Reaction Cross Sections
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