ABSTRACT: In this work, we present the results of verification of special neutron monitoring equipment for use in aircrew dosimetry inside aircraft. The equipment was precalibrated with conventional neutron sources in a National Standard Laboratory of the Institute for Radioprotection and Dosimetry (IRD, Brazil) and verified in a Cosmic Energy Reference Field (CERF), a special field from CERN (Centre Européan de Recherche Nucléaire), a facility that reproduces the shape of neutron field encountered in the atmosphere at aircraft altitudes. The equipment consists of a special neutron probe from Thermo Scientific with response up to 5 GeV neutrons and was verified with respect to ambient dose equivalent rate linearity and angular incidence. The results show the adequacy of the equipment for this type of measurement and the feasibility to use conventional neutron sources to calibrate this specific equipment, in the absence of access to the CERF field.

Abstract: This paper has discussed the guidelines included in the documents of the International Commission on Radiological Protection (ICRP) on radiation protection applicable to aircraft and crew, and this is a brief report of the evolution of studies in this field of activity, as well as the regulations and recommendations already adopted by member countries of the European Union, Canada, and the United States of America. Some peculiarities of the Brazilian airspace and legislation applicable to the work with ionizing radiation are also presented, discussing the general aspects of radiological protection applicable to aircraft crew in Brazil.

Abstract: Aircraft crews are subjected to radiation doses of cosmic origin in the regular exercise of their functions. The present paper gives an estimate of typical doses received by crews of the Flight Test Special Group of DCTA (GEEV) from July 2007 to November 2009. The dose estimates were performed using the CARI-6 and PCAIRE codes and were compared with each other and with values obtained by other authors in other regions of the globe, being analyzed from the standpoint of estimating radiobiological risk.

Resumo: Um detector de nêutrons do tipo "Long-Counter" está sendo utilizado dentro do contexto do projeto DREAB (Dosimetria da Radiação no Espaço Aéreo Brasileiro) para monitorar o fluxo integral de nêutrons oriundos de interação atmosférica da radiação cósmica, o qual tem importância na dose de radiação recebida por seres humanos ao nível do solo e é o principal responsável pela dose recebida por tripulações e instrumentação sensível de aeronaves. Neste trabalho são apresentados os testes preliminares efetuados com o detector de nêutrons do tipo "Long-Counter", utilizando uma fonte de nêutrons de 241Am/Be onde foi avaliada a dependência direcional da resposta do equipamento nos sentidos radial e transversal e também foi verificada a resposta após um acréscimo de retro-blindagem no equipamento, de forma a minimizar o nódulo traseiro de resposta em relação ao nódulo frontal, condição esta de interesse para o trabalho em andamento.

Abstract: A "Long-Counter" neutron detector is being used in the context of the DREAB (Dosimetry of the Radiation in the Brazilian Airspace) project to monitor the integral flow of neutrons deriving from the interaction of cosmic radiation with the atmosphere, which is important for measuring radiation doses received by humans at ground level and is mainly responsible for doses received by aircraft crews and sensitive instrumentation. In this work the preliminary tests performed with the Long-Counter neutron detector are presented using a 241Am/Be neutron source where the radial and transversal directional dependence of the equipment was evaluated and also an additional backward-shield in the equipment was verified, as a way of minimizing the back nodule response in relation to the frontal nodule, which is a condition of interest for the current work in progress.