FNTD radiation dosimetry system enhanced with dual-color wide-field imaging (original) (raw)
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Automatic Neutron Dosimetry System Based on Fluorescent Nuclear Track Detector Technology
Radiation Protection Dosimetry, 2013
For the first time, the authors are describing an automatic fluorescent nuclear track detector (FNTD) reader for neutron dosimetry. FNTD is a luminescent integrating type of detector made of aluminium oxide crystals that does not require electronics or batteries during irradiation. Non-destructive optical readout of the detector is performed using a confocal laser scanning fluorescence imaging with near-diffraction limited resolution. The fully automatic table-top reader allows one to load up to 216 detectors on a tray, read their engraved IDs using a CCD camera and optical character recognition, scan and process simultaneously two types of images in fluorescent and reflected laser light contrast to eliminate false-positive tracks related to surface and volume crystal imperfections. The FNTD dosimetry system allows one to measure neutron doses from 0.1 mSv to 20 Sv and covers neutron energies from thermal to 20 MeV. The reader is characterised by a robust, compact optical design, fast data processing electronics and user-friendly software.
Fluorescent nuclear track detector technology – A new way to do passive solid state dosimetry
Radiation Measurements, 2011
This paper is a review of the latest progress in development of the next generation luminescent dosimetry technique-Fluorescent Nuclear Track Detectors (FNTD) that have important advantages in measuring fast neutrons and high energy heavy charge particles. New Mg-doped aluminum oxide crystals and novel imaging instrumentation for FNTD technology are discussed with regard to application in mixed neutron-gamma fields, medical dosimetry and radiobiological research. Dosimetric characteristics of new detectors are summarized.
Properties of novel fluorescent nuclear track detectors for use in passive neutron dosimetry
Radiation Measurements, 2008
A novel technique for neutron dosimetry has been developed using fluorescent nuclear track detectors (FNTDs) as a possible replacement for CR-39 plastic nuclear track detector (PNTD) technology. New aluminum oxide crystals containing aggregate oxygen vacancies and doped with carbon and magnesium (Al 2 O 3 :C,Mg) are imaged using laser scanning confocal fluorescence microscopy. Advancements in image processing allow for better detection of fluorescence tracks. Dose dependences were obtained for four types of neutron converters. A comparison between enriched 6 LiF (TLD-600) and LiF with natural abundance of 6 Li (TLD-100) was made. Dependence on angle of incidence for fast neutrons was investigated and compared with simulations based on neutron scattering theory. The reusability and re-readability of detectors were tested and confirmed to be satisfactory.
Novel Al2O3:C,Mg fluorescent nuclear track detectors for passive neutron dosimetry
Radiation Protection Dosimetry, 2007
The latest advances in the development of a fluorescent nuclear track detector (FNTD) for neutron and heavy charged particle dosimetry are described and compared with CR-39 plastic nuclear etched track detectors (PNTDs). The technique combines a new luminescent aluminium oxide single crystal detector (Al 2 O 3 :C,Mg) with an imaging technique based on laser scanning and confocal fluorescence detection. Detection efficiency was obtained after irradiations with monoenergetic neutron and proton beams. Dose dependences were measured for different configurations of the detectors exposed in fast-and thermalneutron fields. A specially developed image processing technique allows for fast fluorescent track identification and counting. The readout method is non-destructive, and detectors can be reused after thermal annealing.
Radiation Measurements, 2009
Properties of fluorescent nuclear track detectors (FNTDs) made of Al 2 O 3 :C, Mg crystals are investigated after irradiation in mono-energetic and broad spectrum neutron fields. Two types of neutron converters were investigated, high density polyethylene and natural LiF. Imaging in fluorescence contrast is performed using laser scanning confocal detection. Individual tracks induced by recoil protons, alpha particles and tritium ions are identified and counted. Two approaches to median neutron energy estimation using track density as a function of scanning depth and the ratio of track densities for two different converters are discussed.
Use of SSNTDs in neutron beam dosimetry
Radiation Measurements, 1997
A new Biological Irradiation Facility (BIF) has been constructed at the Budapest Research Reactor Center. The 10 cm diameter beam is led through a variable filter and collimator system, providing different neutron spectra from the nearly pure fission one to a well moderated, I/E spectrum. To use the irradiator for biological irradiation and for investigating the response of neutron detector materials one must know the neutron spectrum, the beam intensity and profile in advance, and moreover, each irradiation should be adequately monitored to be able to correct the dose conversion factors against the burnup of the fuel, change in the reactor thermal power etc. For the purpose, a set of track detectors were developed. All the detectors are chemically etched and evaluated by a new image analyzer system called VIRGINIA (also presented on this conference). Detectors developed are: CR-39 (TASTRAK) track detectors with proton converter (polyethylene, PE) turning this combination into a threshold detector when applying thin gold foils as proton energy degraders; fission track detectors using depleted uranium and thorium with 6 10 LEXAN polycarbonate and CR-39 using the Li and B contents of commercially available TLD materials as alpha converters. We present the basic fundamentals of the proton recoil detector, including the response calculation model.
Neutron dosimetry with solid state nuclear track detectors
1977
A brief review of the application of solid state nuclear track detectors (SSNTDs) in neutron dosimetry is given. The Present state and the most important properties of the SSNTD neutron dosimeters are discussed and their advantages in comparison with other possible detectors are listed. Particular attention is devoted to the applications in personnel neutron dosimetry and here the authors' original work is also described. Possible future applications of SSNTDs in neutron dosimetry are discussed. Both technical improvements and new fundamental approaches are analysed.
Fast-neutron dosimetry by solid-state track detectors
Nuclear Instruments and Methods, 1973
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Applied Radiation and Isotopes, 2020
A simple and low cost alternative which is able to identify thermal and fast neutrons in a clinical environment of radiotherapy is presented. CR-39 and LR-115 Solid State Nuclear Track Detectors (SSNTDs) were used, estimating their viability. In order to register alpha tracks due to thermal neutrons, natural boric acid tablets were placed in close contact to the detector, whereas in order to detect epithermal neutrons, some were additionally covered in a thin cadmium layer. Different configurations were assembled, changing the position of the converter with respect to the detector and the incident neutron fluence, which was evaluated in different positions of a radiotherapy table. The contribution due to environmental 222 Rn and its daughters to the track density registered by the detector during the measurements was found to be negligible. It is concluded that the designed experimental set up constitutes a trustworthy and affordable method to carry out neutron measurements with the recommended configurations provided for the CR-39 detector, and not with LR-115.
A cost effective, highly sensitive, passive neutron fluence monitor for nuclear contraband detection
Natural gadolinium possesses a very high thermal neutron capture (n, g) cross-section on the other hand, carbon-doped aluminium oxide thermoluminescence dosimeters (a-Al 2 O 3 :C), available as TLD 500 are extremely responsive to gamma rays. Hence, by combining those two unique phenomena we have developed a highly sensitive passive neutron detector. The lowest detectable (fission) neutron fluence rate was evaluated to be 7.1 neutrons cm À 2 s À 1 for an integration period of 1 h. This detection level is adequate enough to detect 3 g of 240 Pu from a distance of 1 m, producing spontaneous fission neutrons. Application of this neutron fluence monitor in the passive detection of nuclear contraband is suggested. Further developmental work aiming to augment the present device with instantaneous data display and alarm actuation capabilities is ongoing.