Positional optimization of dosimeters for improved neutron albedo dosimetry
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2024
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SIMPOSIO REPROLAM, 1st
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In this work, we discuss advancements in neutron albedo dosimetry. While personal dosimetry for X, gamma, and beta
radiation is straightforward, challenges arise in mixed-field environments involving neutrons and gamma rays, such as
nuclear plants, accelerators, and space flights [1]. Neutrons exhibit a wide energy spectrum, ranging from thermal neutrons
(~0.025 eV) to fast neutrons exceeding hundreds of MeV [2]. A key aspect of neutron dosimetry is determining the 'dose
equivalent', which accounts for the neutron's 'quality factor', dependent on its energy [3]. Neutrons, high linear energy
transfer (LET) particles, ionize more densely than electrons. Biological effectiveness, indicated by the quality factor (wR), is
2.5 to 20 times higher for neutrons than photons, complicating mixed-field dosimetry [3]. Neutrons interact with atomic
nuclei through several processes, with cross-sections varying with neutron energy and resonances in specific energy ranges
[4]. Materials such as 6Li and 10B have notable (n,a) cross-sections for thermal neutrons [4]. Since the 1970s, various
neutron dosimeters have been developed [1]. However, personal neutron dosimetry faces challenges due to strong gamma
fields, wide-ranging neutron energies, and the difficulty of detecting fast neutrons, which pose higher harm per unit of energy
deposited than thermal neutrons [1]. Effective detection mechanisms must differentiate against low-LET radiations and may
incorporate materials susceptible to neutrons, such as 6Li or 10B, with high cross-sections [2]. Thermal neutrons are
commonly detected using (n,a) reactions. Albedo dosimetry is widely used for personal neutron dosimetry [5]. An albedo
dosimeter measures thermal neutron fluence emitted from the body after exposure to thermal and intermediate neutrons,
moderated and scattered by the body [5]. Detection of reflected thermal neutrons (albedo) uses pairs of thermoluminescent
dosimeters (TLDs), 6LiF (highly sensitive to thermal neutrons) and 7LiF (insensitive to neutrons but sensitive to photons)
[5,6]. Accurate calibration provides reasonable estimates of fast neutron doses. Effective albedo dosimeters require removing
incident thermal neutrons from the radiation field, often achieved by neutron-capturing materials over TLDs [5,6].
Dosimeters are typically worn over the chest; however, lung tissue's lower density makes it more permeable to neutrons,
yielding fewer albedo neutrons for detection. A critical challenge in albedo dosimetry is detecting very fast neutrons, which
penetrate deeply and may not reflect back to the detector, potentially underestimating measured doses.This study aims to
enhance neutron albedo dosimetry by evaluating measurement protocols. We investigated pairs of TLDs sensitive and
insensitive to thermal neutrons across different energies and fluxes in a standard chest phantom, adjusting for dosimeter
placement effects. We combined dosimeters for neutron transmission and reflection, assessing response variations to energy
changes and neutron fluxes. Our presentation will highlight the differences in TLD responses and their implications for
accurate neutron dose assessment.
Como referenciar
LALIC, SUSANA de S.; ALVARENGA, TALLYSON S.; CALDAS, LINDA V.E.; D'ERRICO, FRANCESCO. Positional optimization of dosimeters for improved neutron albedo dosimetry. In: SIMPOSIO REPROLAM, 1st, November 5-8, 2024, Recife, PE. Abstract... Disponível em: https://repositorio.ipen.br/handle/123456789/48885. Acesso em: 26 Mar 2026.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.