To date, the violation of T invariance (TI) has been experimentally established for the decays J. H. Christenson et al., Phys. Rev. Lett.
13
, 138 (1964) and oscillations A. Angelopoulos et al., ...Phys. Lett. B
444
, 43 (1998) of neutral kaons. Phenomenologically, TI violation in the system of neutral kaons is associated with the difference of the Kobayashi–Maskawa phase from zero (or from π) in the standard model of the electroweak interaction. For nucleon–nucleus interactions, this phase turns out to be very small P. Herszeg, in
Symmetries and Fundamental Interactions in Nuclei
, World Scientific, Singapore (1995), p. 89). Estimates of the nucleon–nucleon matrix element corresponding to TI violation in various models are given in V. Gudkov, in
Fundamental Physics with Pulsed Neutron Beams
, World Scientific, Singapore (2001), p. 117. All these estimates are small and have a large spread. Therefore, the verification of TI in nuclear processes actually means a search for other mechanisms for its violation. Below is a description of the experimental methods for TI verification in the total interaction cross sections of low-energy resonance neutrons with unpolarized nuclei with the use of the polarization–asymmetry (PA) theorem.
The reaction induced by the inelastic scattering of 14.1-MeV neutrons on chromium nuclei is studied by means of the tagged-neutron method at the TANGRA (TAgged Neutrons and Gamma RAys) facility ...deployed at Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, and based on the ING-27 standard neutron generator. The energies of visible gamma transitions occurring in various reactions of neutron interaction with chromium nuclei and their partial cross sections are determined. The results obtained by measuring the angular distribution of gamma rays for
Cr are analyzed and are compared with respective results of other experimental studies available in the literature.
Neutron generators are now used in various fields. They produce only fast neutrons; D-D neutron generator produces 2.45 MeV neutrons and D-T produces 14.1 MeV neutrons. In order to optimize ...shielding-collimator parameters to achieve higher neutron flux at the investigated sample (The signal) with lower neutron and gamma rays flux at the area of the detectors, design iterations are widely used. This work was applied to ROMASHA setup, TANGRA project, FLNP, Joint Institute for Nuclear Research. The studied parameters were; (1) shielding-collimator material, (2) Distance between the shielding-collimator assembly first plate and center of the neutron beam, and (3) thickness of collimator sheets. MCNP5 was used to simulate ROMASHA setup after it was validated on the experimental results of irradiation of Carbon-12 sample for one hour to detect its 4.44 MeV characteristic gamma line. The ratio between the signal and total neutron flux that enters each detector was calculated and plotted, concluding that the optimum shielding-collimator assembly is Tungsten of 5 cm thickness for each plate, and a distance of 2.3 cm. Also, the ratio between the signal and total gamma rays flux was calculated and plotted for each detector, leading to the previous conclusion but the distance was 1 cm.
The response function of the BGO, NaI (Tl) and LaBr3(Ce) scintillation detectors to monoenergetic gamma quanta was built on the basis of Monte Carlo simulations using the GEANT4 toolkit and ...calibration measurements with gamma radiation sources of different energies. The response function consists of seven components: the first six constitute the detector’s response to a direct hit of monoenergetic gamma radiation and depend on the properties of the detector (size, material, energy resolution, etc.), and the seventh component represents the effect of surrounding materials on the measured gamma spectrum. For each component of the function, the analytical form of the energy dependence is determined and its parameters are found when registering gamma quanta with energies in the range from 0.3 MeV to 10 MeV.
Inelastic scattering of 14.1 MeV neutrons on iron Fedorov, N. A.; Grozdanov, D. N.; Kopatch, Yu. N. ...
The European physical journal. A, Hadrons and nuclei,
06/2021, Letnik:
57, Številka:
6
Journal Article
Recenzirano
An investigation of inelastic scattering of 14.1 MeV neutrons on an iron sample was carried out using an improved TANGRA (TAgged Neutron and Gamma RAys) setup at JINR (Dubna). The yields of the ...occurring
γ
-transitions and anisotropy of the emitted
γ
-rays were measured using the tagged neutron method. The setup with a high-purity germanium (HPGe) detector was used to obtain the energy spectrum of
γ
-rays. The setup with 18 BGO scintillation detectors positioned in a circle around the sample was used to obtain angular distributions of
γ
-rays. A detailed
γ
-spectrum for
(
n
,
X
γ
)
reactions was obtained and the
γ
-ray angular distribution was measured for the 847 keV and 1238 keV
γ
-transitions. The distribution was fitted by Legendre polynomials up to fourth order and the angular distribution coefficients
a
2
,
a
4
were extracted. A comparison with other published experimental results is given. Model calculations using computer code TALYS 1.9 were performed. The results of calculations are discussed in comparison with the obtained experimental data.
The results obtained by measuring the angular and energy distributions of gamma rays originating from the inelastic scattering of 14.1-MeV neutrons by carbon and oxygen nuclei are presented. The ...measurements in question were performed by the tagged-neutron method in a beam of an ING-27 standard portable neutron generator. The angular distributions of gamma rays emitted by the 2
+
state of
12
С at 4.43 MeVand the 3
−
state of
16
O at 6.13 MeV were obtained.
The results of determining the mass concentration of carbon in soil are discussed. The measurements were made on a facility operating according to the tagged neutron method, which consists of ...irradiating samples with 14 MeV fast neutrons and detecting the characteristic spectra of gamma rays from inelastic neutron scattering at specific time ranges between neutron emission and arrival of the γ-quantum signal. The values of the accuracies of the measurements have been estimated, the standard deviation of the repeated measurements for concentrations of carbon of 1–3% was σ
r
= 0.14%, the convergence to the calculated values was σ
r
= 0.2%.
Gamma-ray detector systems are important instruments in a broad range of science and new setup are continually developing. The most recent step in the evolution of detectors for nuclear spectroscopy ...is the construction of large arrays of detectors of different forms (for example, conical, pentagonal, hexagonal, etc.) and sizes, where the performance and the efficiency can be increased. In this work, a new direct numerical method (NAM), in an integral form and based on the efficiency transfer (ET) method, is used to calculate the full-energy peak efficiency of a single hexagonal NaI(Tl) detector. The algorithms and the calculations of the effective solid angle ratios for a point (isotropic irradiating) gamma-source situated coaxially at different distances from the detector front-end surface, taking into account the attenuation of the gamma-rays in the detector's material, end-cap and the other materials in-between the gamma-source and the detector, are considered as the core of this (ET) method. The calculated full-energy peak efficiency values by the (NAM) are found to be in a good agreement with the measured experimental data.
Tagged neutrons with an initial energy of 14.1 MeV scattered on a carbon sample are measured within the framework of the TANGRA project. Angular distributions of neutrons are obtained for elastic ...scattering and scattering to the first excited state of
12
C with an energy of 4.44 MeV. Results are compared to experimental data from other authors and model calculations performed using a coupled channels model with a deformed optical potential.
Tagged neutrons are used to perform an experimental investigation of the inelastic scattering of 14.1 MeV neutrons on
23
Na and
35
Cl nuclei as part of the TANGRA project at the Frank Laboratory of ...Neutron Physics, Joint Institute for Nuclear Research. The energies and yields of γ quanta for transitions observed in the experiment are measured, and the γ angular distribution coefficients for the highest intensity γ transitions are obtained. The experimental data are compared to others in the literature.
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