The photon self-absorption effect of uranium on the full-energy peak (FEP) efficiency calibration of high purity germanium (HPGe) detector was studied as a function of energy using an activated ...uranium sample has a thickness of 1 mm. The absolute efficiencies of the detector were obtained with the use of gamma standard sources and gamma rays of radionuclides created by irradiating the uranium sample with secondary neutrons. The measurements were carried out with the use of a Planar HPGe detector. MCNP simulation code was used to verify the experimental results. The comparison of the empirical results with the simulation results showed a good agreement. To interpret the efficiencies, the reaction rates were calculated using two methods: (1) - the use of the efficiency curve from the standard sources combined with the self-absorption correction of the uranium material and (2) - the use of the efficiency curve obtained from gamma rays in the sample.
•The effect of self -absorption of photons inside the uranium sample on the efficiency of HPGE detector was studied theoretically and experimentally. The calculated results were compared with the obtained experimental data.•The absolute efficiency curve, which treated the photon self-absorption correction was obtained from gamma rays of the radionuclides formed in the sample.•We developed a new method for the quantitative calculation of reaction products and used in this study.
The flux weighted average cross sections 〈σ〉 and cross sections per equivalent photon σq were first measured for the photonuclear multiparticle reactions natSe(γ, xnyp) at end-point bremsstrahlung ...gamma energies ranging from 20 to 80 MeV. The experiments were performed with the beam from the electron linear accelerator LINAC-200 with the use of the γ-activation technique. The bremsstrahlung photon flux was calculated with the program Geant4. The theoretical values of the flux weighted average cross sections 〈σ〉 and the cross sections per equivalent photon σq were calculated using the partial cross section σ(E) computed with the TALYS package code and the combined model of photonuclear reactions.
Abstract
In this study, experiments were performed at bremsstrahlung end-point energies of 10−23 MeV with the beam from the MT-25 microtron using the
γ
-activation technique. The experimental values ...of relative yields were compared with theoretical results obtained on the basis of TALYS with the standard parameters and the combined model of photonucleon reactions. Including isospin splitting in the combined model of photonucleon reactions allows describing experimental data on reactions with proton escape in the energy range from 10 to 23 MeV. Therefore, taking into account isospin splitting is necessary for a correct description of the decay of the giant dipole resonance.
The activation experiment was performed using the accelerated beam of Phasotron accelerator at the Joint Institute for Nuclear Research (JINR). The natural uranium spallation target QUINTA was ...irradiated with protons with energy 660 MeV. Monte Carlo simulations of neutron production were performed using the Geant4 code. The number of leakage neutrons from the sections of the uranium target surrounded by the lead shielding and the number of leakage neutrons from lead were determined. The total number of fissions in the setup QUINTA was determined. Experimental values of reaction rates for the produced nuclei in the 127I sample were obtained and several values of reaction rates were compared with the results of simulations. Experimentally determined fluence of neutrons in energy interval 10–175 MeV using the (n,xn) reactions in the 127I(NaI) sample was compared with the results of simulations. Possibility of transmutation of the long-lived radionuclide 129I in the QUINTA setup was estimated.
•Natural uranium assembly was irradiated with 660 MeV protons.•Fluence of fast neutrons was measured using 127I(n,xn) reactions.•Monte Carlo simulations provided the information about the number of total fissions in the assembly and number of leakage neutrons from the assembly and from the lead shielding.
Am-241 sample was irradiated in spallation neutrons produced in ADS setup QUINTA at the JINR in Dubna. The energy was 660 MeV in the proton beam. The incineration study method was based on gamma-ray ...spectrometry. During the analysis of the spectra, several fission products were identified. Fission product activities yielded the number of fissions. Nevertheless, the lines are assumed to belong to the neutron capture product covered by parasitic Np-238 decay lines. The Np-238 lines as a result of neutron capture by Np-237 made impossible to determine the number of captures in Am-241.
The cross sections for the reactions
165
Ho(γ, n)
164
Ho,
165
Ho(γ, 3n)
162m
Ho,
165
Ho(γ, 4n)
161
Ho,
165
Ho(γ, 5n)
160m1
Ho,
165
Ho(γ, 5n)
160
Ho, and
165
Ho(γ, 6n)
159
Ho were experimentally ...determined in the energy range from 50 to 110 MeV. Also, calculations were performed using the Geant4 code and the Talys program to determine the cross section of reactions in holmium samples. Calculation results are compared with the obtained experimental results. The dependence of the isomeric ratio
160m1
Ho/
160
Ho on the electron energy has been measured.
The experimental measurement data on the fine structure of beta-decay strength function
S
β
(
E
) in spherical, transitional, and deformed nuclei are analyzed. Modern high-resolution nuclear ...spectroscopy methods made it possible to identify the splitting of peaks in
S
β
(
E
) for deformed nuclei. By analogy with splitting of the peak of E1 giant dipole resonance (GDR) in deformed nuclei, the peaks in
S
β
(
E
) are split into two components from the axial nuclear deformation. In this report, the fine structure of
S
β
(
E
) is discussed. Splitting of the peaks connected with the oscillations of neutrons against protons (E1GDR), of proton holes against neutrons (peaks in
S
β
(
E
) of β
+
/
EC
-decay), and of protons against neutron holes (peaks in
S
β
(
E
) of β
–
-decay) is discussed.
A massive lead spallation target was irradiated with 660 MeV protons to generate a secondary neutron field. The field was studied via measurement of the residual nuclei generation in the lead ...activation samples located inside the target. Experimental results were compared with the Monte Carlo simulations using Geant4 and MCNPX 2.7.0 codes. The comparison shows a general agreement between experiment and simulation and thus serves as a validation of the utilized codes, high-energy nuclear models (ICLXX_HP, BIC_HP, BERT_HP, and INCL4.2) and nuclear data libraries (ENDF/B-VII.1), which can be used for the development of the subcritical accelerator-driven systems in the future.
Abstract
The yields of photonuclear reactions in the
107
Ag,
113
In, and
115
In nuclei were measured. Monte Carlo simulations were performed using the Geant4 code, and the results were compared with ...the experimental values. The isomeric ratios of the yields in the reactions
107
Ag(
γ
,
n
)
106
m
,
g
Ag and
113
In(
γ
,
n
)
112
m
,
g
In were determined, and the cross sections for the reactions
107
Ag(
γ
,
n
)
106
g
Ag and
107
Ag(
γ
, 2
n
)
105
Ag at an energy of 20 MeV were calculated based on the experimental data.
Lead converter was irradiated with electron beams with energies of 60, 80 and 100 MeV. And holmium samples were irradiated with a flux of bremsstrahlung, which was formed in a lead converter. The ...rates of about 20 photonuclear reactions in
165
Ho, which are induced by bremsstrahlung, were measured. Simulations to determine the fluence of electrons, photons, neutrons for holmium samples and the reaction rates for the obtained isotopes in the samples were performed using the Geant4 code. For those radionuclides that are determined in experimental measurements, the results were compared.
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