  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 Sabi\'a 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.
