Fluorescent Nuclear Track Detectors Research Articles

Photoluminescence study of photochromically and radiochromically transformed Al2O3:C,Mg crystals used for fluorescent nuclear track detectors

Abstract Fluorescent nuclear track detector (FNTD) technology is being investigated as a suitable replacement to plastic nuclear track detectors for neutron dosimetry. Imaging of charged particle tracks in Al 2 O 3 :C,Mg crystals is possible due to highly localized radiochromic transformation of F 2 2+ (2Mg) into F 2 + (2Mg) colour centres. The photoluminescence study of Al 2 O 3 :C,Mg crystals subjected to photochromic and radiochromic transformations was aimed to improve crystal performance as a nuclear track detector.

A future plan in observing ultra-heavy nuclei (Z = 30–110) of cosmic rays with large-scale collector at the lunar base

Lunar-based measurement of galactic cosmic ray (GCR) nuclei with a high precision is a challenging approach in cosmic ray research for the coming 20 years. This approach focuses to measure the elemental composition of Pt- and Pb-groups, actinide and possibly trans-uranic nuclei of Pu and Cm. The observation covers a wide range of scientific themes including the study on the origin of GCR nuclei, the characteristic time, heating and acceleration mechanism of GCR particles. A large-scaled particle telescope is required in order to measure those nuclides with high precision. Solid state nuclear track detectors (SSTDs) with a geometric factor of about 1000 m 2sr allow us to measure them easily. Fluorescent nuclear track detector such as Al 2O 3 doped with C and Mg is the best candidate at present among SSTDs for a lunar-based experiment which is currently the focus of an international program of scientific investigation. A permanent sunshine region near crater at lunar polar region is thought to be an excellent site. A two-year-exposure by the large-scaled telescope would result in the detection of about 30,000 actinides in GCRs.

Performance of fluorescence nuclear track detectors in mono-energetic and broad spectrum neutron fields

Properties of fluorescent nuclear track detectors (FNTDs) made of Al 2O 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.

Properties of novel fluorescent nuclear track detectors for use in passive neutron dosimetry

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 2O 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 6LiF (TLD-600) and LiF with natural abundance of 6Li (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.

Spectroscopic properties of novel fluorescent nuclear track detectors for high and low LET charged particles

A new optical, non-destructive method of detecting and imaging individual heavy charged particle tracks using fluorescent nuclear track detectors (FNTD) is investigated as a possible spectroscopic technology for heavy charged particles of low and high linear energy transfer (LET). The technique uses new luminescent aluminum oxide single crystals having aggregate oxygen vacancy defects and doped with Mg ( Al 2 O 3 : C , Mg ) in combination with laser scanning confocal fluorescence microscopy. Spectroscopic capabilities of this new method were demonstrated for energetic heavy ions of LET ∞ H 2 O ranging from 2.2 to 8767 keV / μ m . The new technology is intended for use in neutron detection and dosimetry, proton and heavy ion radiobiology, and space radiation dosimetry as well as in nuclear and particle physics research.

Novel Al2O3:C,Mg fluorescent nuclear track detectors for passive neutron dosimetry

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 thermal-neutron 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.

A novel Al2O3 fluorescent nuclear track detector for heavy charged particles and neutrons

A novel Al2O3 fluorescent nuclear track detector (FNTD), recently developed by Landauer, Inc., has demonstrated sensitivity and functionality superior to that of existing nuclear track detectors. The FNTD is based on single crystals of aluminum oxide doped with carbon and magnesium, and having aggregate oxygen vacancy defects (Al2O3:C,Mg). Radiation-induced color centers in the new material have an absorption band at 620nm and produce fluorescence at 750nm with a high quantum yield and a short, 75±5ns, fluorescence lifetime. Non-destructive readout of the detector is performed using a confocal fluorescence microscope. Scanning of the three-dimensional spatial distribution of fluorescence intensity along the track of a heavy charged particle (HCP) permits reconstruction of particle trajectories through the crystal and the LET can be determined as a function of distance along the trajectory based on the fluorescence intensity. Major advantages of Al2O3:C,Mg FNTD over conventionally processed CR-39 plastic nuclear track detector include superior spatial resolution, a wider range of LET sensitivity, no need for post-irradiation chemical processing of the detector and the capability to anneal and reuse the detector. Preliminary experiments have demonstrated that the material possesses a low-LET threshold of <1keV/μm, does not saturate at LET in water as high as 1800keV/μm, and is capable of irradiation to fluences in excess of 106cm−2 without saturation (track overlap).