Neutron Guide Building instruments of the Brazilian Multipurpose Reactor (RMB) project

Abstract

A growing community of scientists has been using neutrons in the most diverse areas of science. In order to meet the researchers demand in the areas of physics, chemistry, materials sciences, engineering, cultural heritage, biology and earth sciences, the Brazilian Multipurpose Reactor (RMB) will provide 3 thermal guides and 3 cold guides, with the installation of several instruments for materials characterization. In this study, we present a standard design requirement of two primordial instruments, namely Sabiá and Araponga. They are, respectively, cold and thermal neutron instruments and correspond to a Small-Angle Neutron Scattering (SANS) and High-Resolution Powder Neutron Diffractometer (HRPND) to be installed in the Neutron Guide Building (N02) of RMB. To provide adequate flux for both instruments, we propose here an initial investigation of the use of simple and split guides to transport neutron beams to two different instruments on the same guide. For this purpose, we use Monte Carlo simulations utilizing McStas software to check the efficiency of thermal neutron transport for different basic configuration and sources. By considering these results, it is possible to conclude that the split guide configuration is, in most cases, more efficient than cases that use transmitted neutron beams independently of source. We also verify that the employment of different coating indexes for concave and convex surfaces on curved guides is crucial, at least on simulated cases, to optimise neutron flux (intensity and divergence) and diminish facility installation cost. References 21As a multipurpose reactor, the RMB project also contains applications in neutron research and instruments. The neutron applications of the RMB project are the irradiation process, which occurs inside the reflector tank, and measurement process, which takes place at the N02 building (number 14 in Figure 1) and is often complementary to synchrotron radiation investigations. According to the basic project, there will be available in-core positions for materials irradiation tests and positions inside reflector for applying the neutron activation analysis (NAA) technique, which possesses numerous applications, e.g., in geology, archaeology, biology, medicine, environment, industry, chemistry, nutrition, and agriculture.Concerning applications inside N02, the detailed project of RMB contains, according to the main current research reactors, a series of state-of-art instruments that still have to be properly defined. In this study, we present two priority neutron scattering instruments that compose the detailed project of the RMB neutron guide hall (N02), namely Small-Angle Neutron Scattering (SANS) and the High-Resolution Powder Neutron Diffractometer (HRPND).SANS is a flexible and disseminated technique for studying object structures on the nanoscale. Besides its unique property in investigating magnetic material, not contemplated by traditional SAXS technique (Small Angle X-Ray Scattering). SANS is used in looking to polymer and biological molec...

Simulating Araponga - The High Resolution Diffractometer of Brazilian Multipurpose Reactor

“…The results obtained are compatible with state-of-the-art instruments from international installations [6,7]. Our model will receive new attributes after the simulations for the TG1 thermal guide, where the high intensity neutron diffractometer, called Flautim, will be localized [3]. The optimization problem has many variables, such as the choice of collimators and evaluation of beam divergences in curved sections.…”

“…The linear dimensions of the neutron guides, as well as the relative distance to the Reactor Core and the components that make up Araponga can be found in Figure 1. It is important to note that the Araponga instrument is intended to be installed at the end of the TG1 thermal guide [3]. However, the input file to the McStas software contains data referring to the TG2 thermal guide.…”

“…The main objectives of RMB and associated facilities are the production of radioisotopes and radiopharmaceuticals, aiming to meet the entire national demand of the Unified Health System (SUS) and the private network, irradiation and testing of nuclear fuels and structural materials, and the development of scientific and technological research using neutron beams [1,2]. RMB will house the National Neutron Laboratory (LNN), the unit responsible for research activities with a suite of 17 instruments that manipulate neutron beams to investigate the structure of various materials [3]. Among the instruments that make up the LNN is the high-intensity neutron diffractometer, called the Flautim (Schiffornis virescens).…”

Neinei -- The Neutron Imaging Center at the Brazilian Multipurpose Reactor

“…The Brazilian Multipurpose Reactor (RMB) project inaugurates a new era of research on nuclear science and technologies in Brazil and Latin America. Besides the radiopharmaceutical feedstock production, the reactor will allow the study of irradiation in materials and the use of neutron beams to investigate the structures of materials in low dimensions [1,2]. The RMB project has a suite of 15 instruments that use thermal and cold neutrons, allowing the investigation of structures with a wide range of micro and nano scales [2].…”

Monte Carlo simulations of the S-shaped neutron guides with asymmetric concave and convex surface coatings

“…The transportation of neutrons by different types of guides and components has always been a subject of intense scientific activity [1,2,3], from the creation of the first nuclear fission reactors in the 1940s [4] to the recent projects [5,6], and sources of spallation [7]. The theories describing the transportation of neutrons were divided into two groups, the deterministic methods that lead to approximations to solve the Boltzmann equation [8] and the stochastic approach, based on the Monte Carlo method [9].…”