Energy storage in Ce-doped LiCaAlF6 and LiSrAlF6 crystals

Absorption, emission and thermoluminescence (TL) of as-grown and X-irradiated pure and Ce-doped LiCaAlF₆ (LiCAF) and LiSrAlF₆ (LiSAF) crystals have been analyzed. It is shown that the energy storage is defined by the dissimilarity of basic matrix properties, intrinsic defect structure, preferred Ce³⁺ ion disposition and charge compensation defect type. This is the reason of higher colorability and TL efficiency of as-grown Ce:LiSAF compared to Ce:LiCAF. Pre-filling of ultra-deep traps leads to enormous increases in the TL response. Due to these properties Ce:LiSAF and Ce:LiCAF are promising thermoluminescent dosimetric materials.     

Sonochemistry and its dosimetry

The effects of ultrasound originate primarily in acoustic cavitation. The cavitation bubbles collapse violently enough to lead to interesting chemical effects, known as sonochemistry. There is a great need to relate the efficiency of sonochemical reaction to the energy of ultrasonic irradiation used to produce them. In this paper, three OH radical dosimeters, Fricke dosimeter, terephthalate dosimeter, and iodide dosimeter, are compared from the analytical point of view. The dosimeters based on photometry, i.e., Fricke and iodide, produced reliable and reproducible results, but the sensitivity is not enough for special applications, such as chemical monitoring of single bubble cavitation. The dosimeter based on fluorometry, terephthalate dosimeter, offered high sensitivity, 1.2×10¹¹ molecules ml⁻¹. The effects of some experimental parameters in sonochemistry, i.e., solution temperature and the dissolved gas species, were evaluated with the dosimeters.     

Fiber-optic-coupled RbMgF3:Eu for remote radiation dosimetry

A portable fiber optic dosimeter has been developed that incorporates RbMgF₃:Eu²⁺ at the end of a multimode polymer fiber. It uses two stimulation sources and takes advantage of the range of stimulable traps in this compound. We observe radioluminescence (RL) during gamma ray irradiation and show that the low-dose RL increases linearly with increasing dose rate where the minimum detectible dose rate is ∼0.015 μSv/s. We show that pulsed infrared-stimulated (940 nm) optically stimulated luminescence (OSL) can be used for real time dose monitoring. The cumulative dose can be readout after irradiation where a linear OSL dose response was observed when stimulating at 505 nm and the minimum detectable dose is ∼50 μSv.     

Dosimetry for low temperature measurements using single and poly-crystals

The aim of this work was to study the behavior of a single and poly crystalline homemade solid state dosimeters (a) LiF co-doped with Mg, Cu and P, and (b) CaSO₄ doped with Dy. We analyzed the response of these dosimeters using thermoluminiscence. The dose-response at liquid nitrogen temperature was followed to observe the nature of the response.     

Time-integrated monitoring of polycyclic aromatic hydrocarbons (Pahs) in groundwater using the ceramic dosimeter passive sampling device

Passive sampling relies on the uptake of contaminants into appropriate sampling devices along a diffusion gradient without using pumps or bailers. Thus, for example, in groundwater sampling, changes to flow due to pumping can be avoided. If the diffusion gradient can be maintained for extended periods, contaminants can be sampled continuously over time without any action, allowing to determine time-weighted average contaminant concentrations. We here show that the Ceramic Dosimeter, a solid receiving phase passive sampler using a ceramic membrane as sorbent container and diffusion barrier, can be used without calibration for the long-term monitoring of polycyclic aromatic hydrocarbons (PAHs) in groundwater.     

Thermoluminescence characterization of the Cu(Tb,Tm)-12CaO-7AL2O3 compounds obtained by combustion synthesis

The thermoluminescence (TL) properties of dode-calcium hepta-aluminate (Ca₁₂Al₁₄O₃₃) enabled by 12CaO-7Al₂O₃ doped with rare earth and transitions metals ions have been studied and their suitability for radiation dosimetry applications is discussed. It was observed that this calcium aluminate phase doped with Tm-Cu at concentration of 0.1 mol% is a good candidate for dosimetric applications since it presents well-defined single peak observed at 240 °C and 320 °C and a linear response to gamma radiation dose from 5 × 10⁻³ Gy up to 100 Gy.     

Development of human hand phantom containing radiophotoluminescence material

A radiophotoluminescence (RPL) material with high radiation sensitivity was made of polyurethane resin, silver-activated metaphosphate glass particles, and hollow glass microspheres. The density was adjusted to be 1.1 g/cm³ by controlling the amount of hollow glass microspheres. The response to high-energy photons over 100 keV was similar to that of the tissue-equivalent material (polymethylmethacrylate) because the two electron densities were similar. The RPL response had satisfactory linearity in the dose range from 10 to 6 × 10⁴ mGy.An RPL scanner for three-dimensional (3-D) dose measurement was composed of an XYZθ motorized stage, a UV pulse laser, a gated photomultiplier tube (PMT), a red-laser displacement sensor, and an integrating ammeter. The surface profile was measured by the red-laser-displacement sensor. The UV laser was used as an excitation source, and the RPL responses were effectively detected with the gated PMT.An RPL material hand phantom was fabricated to understand the extremity dosimetry of a radiation worker's hand. The hand phantom was exposed to X-rays, and its surface dose profile was obtained by the RPL scanner. Subsequently, the hand phantom was sliced into dozens of square plates using a diamond wire saw. Each inner dose profile was obtained with the RPL scanner. The inner dose profiles were roughly consistent with the computational simulation results. These results indicated that RPL imaging of the hand phantom was useful to understand extremity dosimetry.     

Investigations of OSL properties of LiMgPO4:Tb,B based dosimeters

Lithium magnesium phosphate LiMgPO₄ (LMP) doped with Tb and B is one of new materials intended for use in optically stimulated luminescence (OSL) dosimetry. LMP doped with Tb and B luminophors were synthetized at IFJ PAN in Krakow. The investigations were carried out on self-developed dosimeters consisting of a slide with four LMP detectors and a light tight cover. LMP detectors were investigated in regard to their OSL properties using OSL reader named HELIOS adopted to the readouts of dosimetric cards. New LMP detectors showed high sensitivity to the ionizing radiation, good repeatability of OSL signal and good dose response, 25% of fading in the first two weeks after irradiation. Also, the pronounced dependence of OSL response on the energy of the measured radiation requires to apply the compensation filters.     

Dosimeter properties of MgO transparent ceramic doped with C

We have investigated the photoluminescence (PL), scintillation and thermally-stimulated luminescence (TSL) dosimeter properties of MgO ceramic doped with C ions (0.001, 0.01 and 0.1%). The samples were synthesized by a Spark Plasma Sintering (SPS) technique. The PL emission peaks appeared around 400 and 750 nm in all the samples. The PL decay time constants at 400 nm were ∼10 and ∼100 ns which were on the typical order of F+ center in the undoped MgO. The scintillation emission peaks were detected at 330, 400 and 750 nm under X-ray irradiation. The TSL glow curves showed the ∼250 °C peak in 0.1% C-doped sample. The TSL response was confirmed to be linear to the irradiation dose over the dose range from 0.1 to 1000 mGy. As a result, the sensitivity of MgO was improved by C-doping.