NEUTRON scattering facilities are widely applied to study the properties of materials. A beam of monochomatic NEUTRONs or a widespread wavelength band of NEUTRONs is used to irradiate the sample which is going to be analyzed at the scattering laboratory. Shielding of incident NEUTRONs also the scattered ones from the sample should be definitely done to decrease the laboratory dose rates. Also, mapping of the dose rate distributions helps to the laboratory users to avoid high NEUTRON/gamma exposures. The present study uses a computational method to simulate NEUTRON and gamma dose rates’ distributions inside TRR DIFFRACTION facility laboratory. Not only the simulation method helps to design the laboratory boundary or the laboratory walls so that behind its walls the personal exposures remain as low as possible, but also gives warnings to the facility users about the high dose regions around the beam exit when the facility is under operation. The carried-out work showed after the laboratory boundary, summation of the NEUTRON and gamma dose rates are less than 3 μSv.h-1. In addition, the carried-out benchmark studies by using experimental data in this work confirms the simulations with less than 20% relative discrepancy.

NEUTRON data and cross-sections are highly regarded and are essential for developing nuclear equipment such as advanced fission and fusion reactors, accelerators, NEUTRON shielding, physics studies, etc. The NEUTRON cross-section should preferably be measured using a single-energy NEUTRON beam, although the presence of a background in research reactors can affect its accurate determination. The NEUTRON Powder DIFFRACTION (NPD) facility of Tehran Research Reactor (TRR) has been taken into consideration for measuring the NEUTRON cross-section based on its properties, including NEUTRON monochromator and multiple collimators. In this work, radiative capture cross-sections of Au, In, and Rh materials have been calculated using TRR monochromatic beam. MCNPX is a Monte Carlo particle transport code that has been applied to simulate the measurement system of the NEUTRON cross-section and calculate the reaction rates. The effect of the presence and absence of different sections of the background on the cross-section values was investigated and the results were compared with EXFOR data library for validation. According to the findings, NEUTRON backgrounds can have varying impacts depending on factors such as sample material, the isotope resonance regions, NEUTRON source spatial distribution, and NEUTRON monochromatic energy. However, the presence of fast NEUTRON background contributes to the most uncertainty in the cross section values while its removal produces an average discrepancy from experimental libraries of 7.16%. Also, removing the cold NEUTRON background also causes a relative difference equal to 7.65%.

DIFFRACTION line broadening analysis has been proved to be an extremely powerful method to study the defect properties of crystalline materials, since different types of defects produce different types of DIFFRACTION line profiles. In other word, the distribution of intensity, especially in tails of line profile, strongly depends on the crystallite size and dislocation structures. In this paper, we have applied the second and fourth order restricted moments methods and analysed the NEUTRON DIFFRACTION data collected on Ceria in terms of crystallite size and dislocation density. The values of dislocations density and crystallite size obtained from the second-order restricted moment do not agree with those obtained from the fourth-order restricted moment. This discrepancy is not unexpected when size broadening can not be neglected, the second-order restricted moment does not give correct values for microstructure parameters and therefore these parameters must be evaluated from the fourth-order restricted moment.

A NEUTRON DIFFRACTION technique is used to study the structural characterization of water/ice in mesoporous SBA-15 silica with 86 A nanopore diameter. Different filling factors of the silica pores were considered over a wide temperature range. NEUTRON DIFFRACTION data for the almost-filled case, with a filling factor of 0.95, which undergoes a temperature change of 300-100K, shows a main asymmetric triplet peak 1.74 A-1. Using five symmetric functions, we found an excellent fit with the whole range of data sets for the triplet. Interestingly, each of these functions is directly linked to the position of the different ice components and shows a systematic variation of peak parameters. As a complementary experiment, data analysis of the partially-filled cases, with filling factors of 0.6 (300-130 K) and 0.4 (300-100 K), show characteristics that are markedly different from those of the filling factor 0.95. The nucleation temperature for all cases is reduced and different ice structures, along with their temporal order, have been detected for confined water. Further investigations confirm that for different felling factors, there are different amounts of hexagonal, cubic and disordered ice components. Surprisingly, data analysis proved the reversibility of the whole nucleation process, although the formation/melting of the ice in the main body of the pore showed the expected hysteresis.

We present and compare the magnetic structures of limit compounds, between the ferromagnetism and ant ferromagnetism in the pseudobinary compounds of type RNi/Pt/Cu, where R = Tb, Gd, Nd or Ce, appearing when we substitute the transition metal. All of them are examples of complex magnetic structures as the result of different magnetic interactions, inhomogeneities and disorder. This overview provides us a fruitful field of discussion considering the competition of magnetic interactions in a context of disorder. We discuss the similarities and differences between the structures and we conclude about the importance of the disorder in the existence of several phenomena in magnetism, which could lead to new insights in the stability of magnetic phases, as clusters glass or short range interactions in the mesoscopic scale.  

Fast NEUTRON flux (14.8 MeV) of a NEUTRON generator has been measured by activation technique. The measurements performed using Cu and Ni threshold detectors. 62CU and s7Ni were produced through 63CU (n, 2n) 62Cu and 58ni (n, 2n) 57Ni reactions. They decay by emitting 511 keV and 1377 keV gamma rays, respectively. The half life of 62CU is 9.74 min and that of 57Ni is 36 hours. The flux of NEUTRON has been calculated by measuring the activity after the irradiation time. Gamma spectroscopy of the activated foils was performed using a HPGe detector. By employing this technique the NEUTRON flux of 2.64x107±3% n/s was obtained for 60mA deuteron of 110keV energy, bombarding a solid target of 3H.