@Article{BRIKENCollaborationTarifeno-Saldivia_etal2017, author="BRIKEN Collaboration (Tarife{\~{n}}o-Saldivia, A. et al and Tain, J. L. and Domingo-Pardo, C. and Agramunt, J. and Algora, A. and Morales, A. I. and Rubio, B. and Tolosa, A.", title="Conceptual design of a hybrid neutron-gamma detector for study of beta-delayed neutrons at the RIB facility of RIKEN", journal="Journal of Instrumentation", year="2017", publisher="Iop Publishing Ltd", volume="12", pages="P04006 - 22pp", optkeywords="Detector modelling and simulations I (interaction of radiation with matter; interaction; of photons with matter; interaction of hadrons with matter; etc); Instrumentation for radioactive beams (fragmentation devices; fragment and isotope; separators incl. ISOL; isobar separators; ion and atom traps; weak-beam diagnostics; radioactive-beam ion sources); Neutron detectors (cold; thermal; fast neutrons)", abstract="BRIKEN is a complex detection system to be installed at the RIB-facility of the RIKEN Nishina Center. It is aimed at the detection of heavy-ion implants, {\^I}{\texttwosuperior}-particles, {\^I}{\textthreesuperior}-rays and {\^I}{\texttwosuperior}-delayed neutrons. The whole detection setup involves the Advanced Implantation Detection Array (AIDA), two HPGe Clover detectors and a large set of 166 counters of 3He embedded in a high-density polyethylene matrix. This article reports on a novel methodology developed for the conceptual design and optimisation of the 3He-tubes array, aiming at the best possible performance in terms of neutron detection. The algorithm is based on a geometric representation of two selected parameters of merit, namely, average neutron detection efficiency and efficiency flatness, as a function of a reduced number of geometric variables. The response of the detection system itself, for each configuration, is obtained from a systematic MC-simulation implemented realistically in Geant4. This approach has been found to be particularly useful. On the one hand, due to the different types and large number of 3He-tubes involved and, on the other hand, due to the additional constraints introduced by the ancillary detectors for charged particles and gamma-rays. Empowered by the robustness of the algorithm, we have been able to design a versatile detection system, which can be easily re-arranged into a compact mode in order to maximize the neutron detection performance, at the cost of the gamma-ray sensitivity. In summary, we have designed a system which shows, for neutron energies up to 1(5) MeV, a rather flat and high average efficiency of 68.6{\%}(64{\%}) and 75.7{\%}(71{\%}) for the hybrid and compact modes, respectively. The performance of the BRIKEN system has been also quantified realistically by means of MC-simulations made with different neutron energy distributions.", optnote="WOS:000405067800006", optnote="exported from refbase (https://references.ific.uv.es/refbase/show.php?record=3209), last updated on Tue, 13 Oct 2020 12:50:39 +0000", issn="1748-0221", doi="10.1088/1748-0221/12/04/P04006", opturl="http://arxiv.org/abs/1606.05544", opturl="https://doi.org/10.1088/1748-0221/12/04/P04006", archivePrefix="arXiv", eprint="1606.05544", language="English" }