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Innovative approach for dosimetry in continuous and pulsed neutron fields

Type of activity
Competitive project
Funding entity
AGAUR. Agència de Gestió d'Ajuts Universitaris i de Recerca
Funding entity code
2018-LLAV00039
Amount
20.000,00 €
Start date
2019-05-01
End date
2019-10-31
Keywords
detectors de les radiacions ionizants, dosimetria, neutrons
Abstract
Aim
To develop a neutron REM-counter able to overcome the limitations of present dosimeters in pulsed neutron fields.
Premise
Neutrons are intentionally used, or incidentally created in various scenarios. Depending on the neutron energy, this kind of radiation can dominate the total dose received in a given facility. Thus, the detection of neutrons, for radiation protection purposes, is an important topic in areas such as radiotherapy, basic research, nuclear power plant, etc. One of the most habitual detector for this purpose is the so-called REM counter. It consists of a thermal neutron counter embedded in a moderator, which extends the detector sensitivity up to higher energies. The moderator geometry is designed so that detector’s response provides a direct conversion of the neutron fluence into ambient dose equivalent (H*(10)). Present days REM counters are based on analog electronics and were developed during the late nineties. The actual technology relies on the identification and counting of single neutron events for the measurement of the dose rate (counting rate). Thus, commercial probes are well suited for neutron fields where the neutron intensity is stationary (continuous field) and low enough to avoid overlapping of multiple events (pile-up) in the electronic chain.
Nevertheless, there are strong concerns about the reliability of commercial REM counters for transients and pulsed neutron fields. In fact, recent studies have shown that most REM counters in the market might underestimate neutron dose by up to three orders of magnitude in pulsed fields [CAR14]. In terms of Radiation Protection, this is a major issue in, at least, the fields of: a) particle accelerator (radiotherapy, scientific facilities, etc.), due to beam losses, b) pulsed neutron beams facilities for basic research and applications, and, c) high power pulsed lasers.
Proposal
The limitations of commercial REM counters in pulsed neutron fields can be surpassed by using Charge Integration. In this case, the counting rate, and thus the dose rate, is obtained from the total charge generated (total energy deposited in the active volume of the detector) by the neutron burst in the counter. Such a technique can be implemented for neutron dosimetry by an innovative design of the electronic chain and the use of a digital data-acquisition system. This concept of charge integration has been already used by our group in the development of neutron beam monitors for research experiments in pulsed fusion plasmas. The goal of this proposal is to further exploit the charge integration concept in developing a demonstrator REM counter able to cope with continuous, transient and pulsed neutron fields. The device will use digital electronics. Therefore, the system would allow to combine both approaches, single event counting and charge integration, in a flexible device able to provide an online monitoring of the neutron dose and a direct comparison against commercial REM counters. The demonstrator, once developed, will be validated in relevant environments including neutron fields produced by radioactive sources and pulsed facilities.
It is worth to mention that, the European Radiation Dosimetry Group (EURADOS) in its Strategic Research Agenda (SRA), included “The development of new neutron dosimetry techniques” as its second priority among nineteen challenges identified in 2018 [EUR18].
[CAR14] M. Caresana et al. Nucl. Instrum. Methods A 737 (2014) 203-213 https://doi.org/10.1016/j.nima.2013.11.073 .
[EUR18] GAP ANALYSES from EURADOS, Strategic Research Agenda, www.eurados.org
Scope
Adm. Generalitat
Plan
Estratègia de recerca i innovació per a l'especialització intel·ligent de Catalunya (RIS3CAT)
Call year
2019
Funcding program
RIS3CAT
Funding call
Ajuts a projectes innovadors amb potencial d'incorporació al sector productiu
Grant institution
Agència De Gestió D'ajuts Universitaris I De Recerca (agaur)

Participants