Dosimetry Applications Research Articles

Luminescence properties of SrB6O10:Ce,Gd phosphor for applications in OSL dosimetry and lighting

Strontium hexaborate (SrB6O10) doped with different metals and/or lanthanides has been studied widely as the thermoluminescence (TL) dosimeter. However, there is almost no dosimetry study concerning the utility of Optically Stimulated Luminescence (OSL) on SrB6O10. This preliminary study aims to examine the luminescence properties of SrB6O10 phosphor for their application in the areas of dosimetry and lighting technologies. Undoped and doped material to get an OSL dosimeter were synthesized by incorporating the dopants Ce3+, in the range of 0.1–0.7 % wt, and Gd3+, in the range of 0.1–1 % wt into the SrB6O10 structure using the solution combustion (SCS) method. The structural and morphological characterizations were performed using X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) methods, respectively. Two TL peaks of SrB6O10:Ce0.1%,Gd0.5% occurred at 70 °C and 182 °C after 1 Gy exposure to beta rays with a heating rate of 2 °C/s. The step annealing measurements were carried out to determine the traps responsible for the OSL signal. Various properties of the luminophore including dose-response and reusability were investigated using blue light stimulation. The phosphor showed a little variation of response up to 20 cycles within 2 % deviation (STD) from the first OSL readout. The OSL output within the range of 2–20 Gy was determined as linear. Radioluminescence (RL) measurement was investigated by emission in the range λem = 200–1000 nm. The parent compound displayed UV emission subdivided into UVA (315–400 nm), and UVB (280–315 nm) emissions at room temperature. The Chromaticity Coordinates (CIE) of SrB6O10:Ce0.1%,Gd0.5% were calculated as x = 0.2165, y = 0.1767. These remarkable characteristics show that, if developed, SrB6O10 could be used as an OSL dosimeter.

Radiophotoluminescence response of LiF:Mg,Ti pellets irradiated with clinical proton beams in the 70–200 MeV energy range

Lithium fluoride doped with Mg and Ti (LiF:Mg,Ti) has been used for several decades as thermoluminescent dosimeter material, but recently also its radiophotoluminescence has been investigated for applications in dosimetry. In this work, LiF:Mg,Ti pellets (TLD-100) were irradiated in a water phantom at CNAO (Pavia, Italy) with therapeutic proton beams at five energies from 70 to 200 MeV in the dose range from 2 to 20 Gy. After irradiation, their visible radiophotoluminescence spectra were measured in controlled conditions and the spectrally-integrated red emission response of radiation-induced color centers has been investigated. The radiophotoluminescence signal, excited by a 445 nm continuous wave laser, was integrated within a 50 nm-wide band around the emission peak of the F2 color centers, located around 670 nm in LiF. The spectrally-integrated signal of the samples irradiated at the energy of 147.7 MeV exhibited a linear dependence with dose. Moreover, this radiophotoluminescence response appears independent from Linear Energy Transfer in the range from 0.8 to 1.6 keV/μm in all the samples irradiated at the dose of 5 Gy. Such independence was found up to 10.3 keV/μm in samples irradiated within two spread out Bragg peaks made of 36 energy components in the entire investigated proton energy range. The radiophotoluminescence response of the TLD-100 pellets was compared to that of nominally-pure LiF crystals irradiated in the same conditions, which show a similar behavior. The results are encouraging for the exploitation of TLD-100 pellets as passive solid-state radiophotoluminescent dosimeters for proton therapy.

Elucidation of trap energies of Gamma-irradiated BaMgAl10O17: Ce3+ phosphors for dosimetry applications

This paper presents a comprehensive examination of the thermoluminescence properties of BaMgAl10O17: Ce (BAM: Ce) phosphors, which were synthesized via the combustion method. The study employs five distinct approaches to determine the kinetic parameters for individual traps. To investigate the structural, morphological, and elemental composition of the samples, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were utilized. The photoluminescence spectra revealed a broad emission centered around 420 nm upon 330 nm excitation. By subjecting the phosphors to γ doses ranging from 5 to 5 kGy and conducting TL glow curve analysis, the kinetic characteristics of the BAM: Ce phosphors were determined. The linear dose–response was observed for 5–50 Gy, indicating a high sensitivity value. Additionally, there is a consistent estimation of trap energy across various methods. It is also worth noting that the phosphor exhibits a very low minimum detectable dose, estimated to be in the microgray range, making BAM: Ce a strong candidate for low gamma dosimetry applications.

Investigation of the electronic band gap tuning by Si doping on BeO using UV–VIS spectroscopy and density functional theory

BeO with tissue equivalent features promising dosimetric properties, making BeO particularly suitable for being used in all dosimetry applications. In this work, BeO was synthesized and doped with Si using sol-gel and solid-state methods, respectively. To find the optical band gap of Si-doped BeO nanoparticles (BeO:Si) experimentally, the ultraviolet-visible (UV–Vis) spectroscopy was used. To simulate the electronic band structure of BeO and Si-doped BeO, we used the QUANTUM ESPRESSO code based on density functional theory (DFT). The calculated electronic band structure exhibited insulator behavior and the band gap decreased with Si doping in two potential types. Compared to BeO, a shift toward lower energies was determined from the UV–Vis absorption spectrum of BeO:Si, the simulated and the experimental band gaps were found to be in good agreement. These findings offer insights into the dopant syntheses of BeO and their widespread use for fundamental studies as well as their potential applications.

Structural Properties of Thermoluminescence Dosimeter Materials, Preparation, Application, and Adaptability: A Systematic Review

Thermoluminescence dosimeters (TLDs) are widely used in radiation dosimetry due to their excellent properties, such as high sensitivity, small size, and ability to measure low doses of radiation. This review focuses on the structural properties of TLD materials, as well as their preparation, application, and adaptability. The review covers the various types of TLD materials, crystal structure, and properties, including energy response and fading characteristics. The different methods used to prepare TLD materials, such as solid-state synthesis, sol-gel synthesis, and solution growth methods, are discussed in detail. The review also includes a detailed discussion of the various applications of TLDs, including medical, environmental, and industrial radiation dosimetry. Extensive information on TLD is reviewed, and the TL characteristics that have a noticeable impact on the TL dosimetry potential for human and other purpose utilisation, such as mineral, oil, and gas resource investigation, can be done using natural and artificial TL signals. Information on TL measurement process requirements and the TL characteristics that have a noticeable impact on a compound TL dosimetry potential are also addressed. Finally, the review concludes by highlighting the adaptability of TLD materials to different dosimetry applications and their potential use in the future.

Investigation of structural, photo and thermoluminescence properties of YAGG:Ce nanogarnet for medical dosimetry application

Cerium-doped yttrium aluminum gallium garnet (YAGG:Ce3+) nanophosphors were synthesized using the sol-gel method. Mixed garnet of Y2.97Al5-xGaxO12:Ce0.03 was prepared with varying gallium content: x = 0, 1, 2 and 3 Ga. The effect of gallium substitutions on the structural, photo and thermoluminescence properties of the prepared nanophosphors were studied by X-ray diffraction (XRD), photoluminescence (PL) and thermoluminescence (TL) techniques. XRD results indicated that the single and pure cubic crystal phase was formed for all nanophosphor samples regardless of the Ga content. The PL spectra of all the samples exhibited a green-yellow emission band centered at 522 nm attributed to the 5d → 4f transitions of Ce3+ ions. The TL glow curve spectra recorded after β-particle irradiation showed a strong dependence in terms of position, shape and intensity, of all temperature peaks with the Ga content. The highest TL sensitivity was observed for the sample prepared with x = 2 Ga, with main peak arising at low temperature (85 °C). The sample prepared at x = 1 Ga exhibited also high TL sensitivity with a simple glow curve spectrum showing a main peak at high temperature (∼158 °C). Thus, the linear dose response of this sample has been investigated in the wide dose range from 0.125 to 100 Gy in order to evaluate the potentiality of this material for radiation dosimetry applications.

Optical properties of thin films monitored in real-time at high gamma radiation doses using long period fiber gratings

In this work, we report an all-optical-fiber-based method to monitor in real-time the changes in thin film optical properties when exposed to harsh environments such as high doses of gamma radiation. The method is based on a long period grating (LPG) inscribed in a radiation resistant optical fiber, which is coated with a thin film to be analyzed. Due to impact of the environment on the film properties, the transmission spectrum of the LPG changes. To validate this methodology, we deposited oxides of various metals, i.e. aluminum (Al2O3), titanium (TiO2), and tantalum (Ta2O5), as well as a polymeric film, namely polystyrene (PS), on the LPG surface and measured the resonant wavelength shift induced by high doses of gamma exposure (dose rate of 2.3 kGy/h, up to a total dose of 46 kGy). The changes could be observed in real-time up to maximum reached dose and during the recovery period. The results are significantly dependent on thin film material. Among the oxides, TiO2 thin film demonstrated the highest susceptibility to irradiation, whereas Al2O3 exhibited the least impact. Additionally, a good recovery potential for Ta2O5 thin film was observed, hinting at its promising application in dosimetry. Conversely, the PS film exhibited a permanent effect induced by irradiation. This is the first real-time experimental study of the impact of high dose gamma radiation on thin film optical properties using a universal optical-fiber-based device. The findings pave the way for assessing radiation hardness of thin film materials or utilizing such a method to optimize material treatment involving ionizing radiation.

Local environment in yeast-based impedance biodosimeters strongly influences the measurable dose

This work investigates the feasibility of yeast-based impedance measurements for retrospective dosimetry applications. The local environment around yeast cells in a previously developed film-badge was modeled using Geant4. A greater dose response was observed when yeast cells were surrounded by an aluminum-polymer structure, which acted as a conversion layer. Bench-top experiments were conducted using a jar-based dosimeter design that directly combined a finely-ground aluminum conversion medium with yeast powder. It was shown when irradiated in the presence of aluminum grains, yeast cells yielded a higher impedance signal, thereby indicating greater radiation-induced damage. Finally, in separate irradiation experiments, lead and aluminum sheets were placed behind yeast samples and the dosimeters were irradiated to 1 Gy. A 2-fold increase in the impedance signal was shown when samples were positioned in close contact with the lead sheet compared to the aluminum sheet. In all experiments, it was shown that the local environment significantly influences radiative energy deposition in yeast cells.

Effect of helium ion and gamma irradiation on the TL and OSL properties of Tb-doped LiF nanophosphors

Lithium Fluoride (LiF) stands out as a extensively researched material in Thermally Stimulated Luminescence Dosimetry (TLD). This study specifically delves into nanocrystalline Tb-doped LiF TL dosimeters, synthesized through the co-precipitation method, and evaluates their efficacy under He ion and gamma rays radiation. Morphological examination via transmission electron microscopy has revealed cubic-shaped particles. These particles were subjected to irradiation by 120 keV He ion beams ranging from 1014 to 1016 ions/cm2 and gamma rays ranging from 10 to 1000 Gy, facilitating a comprehensive comparative analysis. Deconvolution of the glow curves enabled the extraction of trapping parameters. Under gamma irradiation, the nanophosphor exhibited a distinctive, intense single TL glow peak centered at 400 K with a minor hump at 512 K, diminishing with increasing doses. Conversely, under He ion irradiation, the nanophosphor displayed a peak at 492 K, accompanied by a slight shoulder around 600 K. Additionally, gamma doses displayed a highly promising response to Optically Stimulated Luminescence (OSL). Fading studies further underscore its suitability for radiation dosimetry applications. The unique characteristics of the TL glow curve, dose-response behaviours, and OSL responses highlight the versatility and effectiveness of these nanophosphors in radiation dosimetry, making significant contributions to advancements in this field.

Thermoluminescent dosimeters (TLD-100) for absorbed dose measurements in alpha-emitting radionuclides

Early works that used thermoluminescent dosimeters (TLDs) to measure absorbed dose from alpha particles reported relatively high variation (10%) between TLDs, which is undesirable for modern dosimetry applications. This work outlines a method to increase precision for absorbed dose measured using TLDs with alpha-emitting radionuclides by applying an alpha-specific chip factor (CF) that individually characterizes the TLD sensitivity to alpha particles. Variation between TLDs was reduced from 21.8% to 6.7% for the standard TLD chips and 7.9% to 3.3% for the thin TLD chips. It has been demonstrated by this work that TLD-100 can be calibrated to precisely measure the absorbed dose to water from alpha-emitting radionuclides.

Evaluation of TL and OSL signals of MgB4O7:Tm,Li prepared by the solution combustion method

Magnesium tetraborate (MgB4O7) doped with rare-earth elements is recognized for its suitability in thermoluminescence (TL) dosimetry due to its low effective atomic number (Zeff = 8.4) and the potential applications in neutron dosimetry. The study investigates the luminescent (TL and OSL) properties of MgB4O7 doped with thulium (Tm3+) and lithium (Li+). Samples were synthesized using the solution combustion method and TL and OSL responses were evaluated using a spectrometer and an automated OSL/TL reader. The emission lines of Tm3+ are consistent with previous literature, with Li+ enhancing TL and OSL responses. TL emission spectra unveil distinct bands corresponding to [Tm3+]* transitions. The electron paramagnetic resonance (EPR) spectroscopy analysis carried out in unirradiated, irradiated and annealed samples.The results show that the signals corresponding to BO32− and O2− are seen upon irradiation and disappear after annealing at 200 °C, indicating the participation of these centers in the TL process. The results show that the TL response of MgB4O7:Tm,Li is much more sensitive to gamma radiation than MgB4O7:Tm, with a minimum detectable value of 0.084 mGy and a linear response with dose for the range studied, from 0 to 500 mGy, with R2 of 0.998.

Experimental evaluation of electrospun ZnO/WO3/PVA-coated glass nanocomposites for a potential radiation dosimetry application

This research aimed to fabricate a potential radiation dosimeter using electrospun ZnO/WO3/PVA-coated glass nanocomposites. Samples with varying ZnO molarities (2.46, 3.69, 4.91, 5, and 7 M) and 5 wt% of WO3 collected at different times were examined. Field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDX) revealed favorable nanofiber morphology, although certain conditions produced larger nanofibers. The optical properties, analyzed via ultraviolet–visible (UV–Vis) spectroscopy, exhibited varying responses in different samples with changes in nanofiber collection time. The calculated optical energy band gap (Eg) for all samples is lower than Eg of pure ZnO. Moreover, the effective atomic number (Zeff), calculated based on EDX results, did not approach Zeff of human tissues, in all samples in general. Crucially, all samples demonstrated a strong linear response and low energy dependence when subjected to different X-ray exposure settings, closely resembling an Al2O3-based OSL dosimeter. Sample E3, consisting of 7.00 M ZnO and 5 wt% of WO3 collected over 4 h, emerged as the most promising candidate for a radiation dosimeter. Prior studies neglected to examine the influence of different amounts of ZnO on the radiation dosimetry properties of ZnO/WO3/PVA nanofibers. In contrast, this study specifically investigated the radiation dosimetry properties of ZnO/WO3/PVA nanofibers. The exceptional properties of ZnO in response to X-rays, combined with the desired X-ray attenuation capabilities of WO3, make them a distinct option as substitute materials in radiation dosimeters. This research paves the way for an alternative dosimeter solution with robust radiation detection capabilities.

Investigations of swift heavy ion induced thermoluminescence effect, trapping parameter analysis, and density functional theory of MgB4O7: Eu phosphor

The present work reports swift heavy ion (SHI) induced thermoluminescence (TL) dosimetric properties and density functional theory (DFT) studies of Eu doped MgB4O7 phosphor. Comparative investigations of structural, and luminescent properties of MgB4O7:Eu phosphor upon irradiation by 100 MeV Ag7+ and Ni7+ ion beams at the varied fluence range from 1 × 1010 ion/cm2 to 5 × 1012 ion/cm2 are presented systematically. Eu doped MgB4O7 phosphor is prepared by facile hydrothermal method. X-ray diffraction pattern of the material reveals its orthorhombic structure with crystallite size of ∼30 nm. Fourier transform infrared spectroscopy (FTIR) studies demonstrate loss of crystallinity of material after the SHI irradiations. Correlation of stopping powers and projectile range calculations is performed using SRIM software. The investigated photoluminescence properties show emission bands located in the orange-red region with prominent peaks centered at ∼593 nm and ∼625 nm corresponding to 5D0→7F1 and 5D0→7F2 transitions of Eu3+ion. The influence of ion beam fluence on the photoluminescence properties has been explored. Variation in the intensity of the PL peaks without any shift in the peak positions is observed at different ion fluence. The TL glow curve of phosphor exhibits two major dosimetric peaks (a) at 185 °C and 275 °C and (b) at 172 °C and 273 °C upon Ag7+ and Ni7+ ion beam irradiation respectively. The phosphor shows fairly good linear dose response in the range of 1 × 1010 ion/cm2 to 5 × 1012 ion/cm2. Fading measurements reveal 10% and 12% fading for the irradiation of Ag7+ and Ni7+ ions respectively in two months. Trapping parameter calculations of SHI irradiated phosphors are carried out via various TL glow curve analysis methods such as, peak shape method, whole glow peak method, and glow curve deconvolution method. Efficient thermoluminescence properties of MgB4O7:Eu make it a potential phosphor material and promise to provide avenue into swift heavy ion dosimetry applications. DFT computational studies performed to obtain the electronic structure of Eu doped MgB4O7 phosphor support the experimental results of crystal structure, symmetry and electronic structure studies.

Development of Dy3+ doped lithium magnesium borate glass system for thermoluminescence based neutron dosimetry applications

Abstract The manuscript reports the synthesis of Dy3+ incorporated lithium magnesium borate glass by melt quenching technique. FTIR study revealed the presence of both BO3 as well as tetrahedral BO4 units through their characteristic frequencies. Photoluminescence (PL) study of unirradiated samples confirmed the presence of Dy dopant in the ‘+3’ oxidation states from the characteristic emissions at 482, 578, 666 and 716 nm corresponding to 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2, 4F9/2 → 6H9/2 transitions, respectively. Thermal neutron and gamma irradiated PL emission and lifetime characteristics were discussed in details based on the different defect centers. Thermal neutron irradiated TL study showed that the material has a broad and single dosimetry glow peak at about 450 K which showed high fading due to low temperature peak. TL based neutron sensitivity of LMB: Dy3+ was found to be about 37.4 times less than that of standard TLD-100 (LiF: Mg, Ti) powder. The net TL response from about 3 to 83 mSv of neutron dose was found to be linear (Adj. R2 = 0.9994) which is one of the most desirable properties for dosimetry applications. In addition, the TL trap parameters were evaluated using both deconvolution of TL glow curve and peak shape method as suggested by Chen which were found to be matching with each other.

Luminescence properties of Ce and Be-doped CaAl12O19 for dosimetric and light-emitting applications

In this study, we reported the sol-gel production of cerium (Ce) and beryllium (Be)-doped calcium aluminate (CaAl12O19) and its luminescence properties for optically stimulated luminescence (OSL) dosimetry and light-emitting applications. Structural, morphological and elemental characteristics of the samples were examined by x-ray diffraction (XRD), Scanning electron microscope (SEM)/energy dispersive spectrum (EDS), x-ray fluorescence (XRF) and Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) techniques. The maximum OSL intensity was achieved with 0.5 and 2% mol concentrations of Ce and Be dopants, respectively. We investigated the OSL and thermoluminescence (TL) properties of Ce and Be-doped CaAl12O19 by measuring energy storage for 24 h, dose-response in the range of 0.1 and 20 Gy, and reusability of the samples for 15 cycles. Photometric properties of the phosphors were investigated by evaluation of CIE chromaticity coordinate (x, y), CCT, and colour purity using its corresponding photoluminescence (PL) emission spectra. We also applied computerized glow curve deconvolution (CGCD), various heating rate methods, and the Tm-Tstop procedure to determine the trap localizations associated with the TL glow curve. The results of this study point out that CaAl12O19 crystals have the potential to be used as OSL dosimetry when appropriate dopants are used. This study may offer new possibilities in radiation dose detection and monitoring.

Thermoluminescence characteristics of gamma-irradiated nano-alumina

The focus of this study lies in exploring the properties of thermoluminescence (TL) in nano-alumina, including the correlation between TL intensity and absorbed dose, identification of individual luminescence peaks, and investigation of trap parameters for potential dosimetry applications. The samples were irradiated by 60Co with doses ranging from 530 to 2646 Gy. Micro-sized α-Al2O3 had a prominent dosimetry peak at maximum temperature Tm = 435 K. Nano-α-Al2O3 samples with 40 and 50 nm particle sizes exhibited a TL luminescence glow curve, with the main dosimetry peak in the low-temperature region and a complex structure at higher temperatures (above 500 K). The observed maximum of the main dosimetry peak depended on the nanoparticle size and was 460 K for the sample with particle size of 40 nm and 467 K for 50 nm. The main dosimetry peak was described by the superposition of the two peaks.A computerized glow curve deconvolution method was applied to determine the parameters of the traps responsible for TL using the Microsoft Windows-operated GlowFit program, assuming first-order kinetics. The found values of the activation energies were 0.97 ± 0.01 eV for the trapping center responsible for the peak with Tm = 458 ± 3 K and, accordingly, 1.05 eV for the peak with Tm = 473 ± 3 K. The estimated values of the frequency factor were s ≈ 1.01 × 1010 and 1.3 × 1010 s−1 for the peak with Tm = 458 ± 3 K, and 2.06 × 1011 s−1 for the peak with Tm = 473 ± 3K, respectively. The lifetime for the traps in nano-α-Al2O3 was estimated as 43–56 days for the first trap and approximately 65 days for the second trap. It is assumed that these traps are responsible for TL emission at the low-temperature part of the glow curve.

Characterization of a flexible a-Si:H detector for in vivo dosimetry in therapeutic x-ray beams.

The increasing use of complex and high dose-rate treatments in radiation therapy necessitates advanced detectors to provide accurate dosimetry. Rather than relying on pre-treatment quality assurance (QA) measurements alone, many countries are now mandating the use of in vivo dosimetry, whereby a dosimeter is placed on the surface of the patient during treatment. Ideally, in vivo detectors should be flexible to conform to a patient's irregular surfaces. This study aims to characterize a novel hydrogenated amorphous silicon (a-Si:H) radiation detector for the dosimetry of therapeutic x-ray beams. The detectors are flexible as they are fabricated directly on a flexible polyimide (Kapton) substrate. The potential of this technology for application as a real-time flexible detector is investigated through a combined dosimetric and flexibility study. Measurements of fundamental dosimetric quantities were obtained including output factor (OF), dose rate dependence (DPP), energy dependence, percentage depth dose (PDD), and angular dependence. The response of the a-Si:H detectors investigated in this study are benchmarked directly against commercially available ionization chambers and solid-state diodes currently employed for QA practices. The a-Si:H detectors exhibit remarkable dose linearities in the direct detection of kV and MV therapeutic x-rays, with calibrated sensitivities ranging from (0.580±0.002) pC/cGy to (19.36±0.10) pC/cGy as a function of detector thickness, area, and applied bias. Regarding dosimetry, the a-Si:H detectors accurately obtained OF measurements that parallel commercially available detector solutions. The PDD response closely matched the expected profile as predicted via Geant4 simulations, a PTW Farmer ionization chamber and a PTW ROOS chamber. The most significant variation in the PDD performance was 5.67%, observed at a depth of 3mm for detectors operated unbiased. With an external bias, the discrepancy in PDD response from reference data was confined to±2.92% for all depths (surface to 250mm) in water-equivalent plastic. Very little angular dependence is displayed between irradiations at angles of 0° and 180°, with the most significant variation being a 7.71% decrease in collected charge at a 110° relative angle of incidence. Energy dependence and dose per pulse dependence are also reported, with results in agreement with the literature. Most notably, the flexibility of a-Si:H detectors was quantified for sample bending up to a radius of curvature of 7.98mm, where the recorded photosensitivity degraded by (-4.9±0.6)% of the initial device response when flat. It is essential to mention that this small bending radius is unlikely during in vivo patient dosimetry. In a more realistic scenario, with a bending radius of 15-20mm, the variation in detector response remained within±4%. After substantial bending, the detector's photosensitivity when returned to a flat condition was (99.1±0.5)% of the original response. This work successfully characterizes a flexible detector based on thin-film a-Si:H deposited on a Kapton substrate for applications in therapeutic x-ray dosimetry. The detectors exhibit dosimetric performances that parallel commercially available dosimeters, while also demonstrating excellent flexibility results.

LiZnBO3 phosphor for dosimetry applications

This study explores the dosimetric potentials of pristine lithium zinc borate, LiZnBO3, (LZB) phosphor for medical application. The pristine LZB was synthesized by the solid-state reaction (SSR) technique. The structural properties of the synthesized composites were investigated by X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) measurements. The FT-IR data shows that the functional groups are responsible for the peak intensity of LZB. The magnetic hysteresis (M-H) loop was characterized using Vibrating Sample Magnetometry (VSM) to distinguish its magnetic characteristics and alterations. From the M-H loop, it behaves as a superparamagnetic material. A clinical Linear Accelerator (LINAC) was used to irradiate the samples with both electron (6 MeV) and X-ray photon beam (6 MV), with a dose range of 0.5 Gy–8 Gy for both beams. The experiment was designed to study low to medium-dose TL response for LZB. The irradiated samples were readout for thermoluminescence (TL) signal using a Harshaw-3500 TL reader with a fixed heating rate of 10 °C/s. The TL kinetic parameters of the composites were studied by analysing the glow curves using the peak-shape method. The geometric factor (μg) is found to be within the range of 0.42–0.52, which indicates the suitability of applying Chen's general-order formula to calculate kinetic parameters. The activation energy (E) is found in the range of 1.13–3.14 eV for 4 deconvoluted peaks of 6 MeV electron beam irradiation and 1.82–2.16 eV for 3 deconvoluted peaks of 6 MV X-ray photon beam irradiation. The frequency factor (s) also increases while activation energy increases for both electron and X-ray photon beams. All the obtained results confirm the suitability of LZB phosphor to develop a viable radiation dosimeter.

Influence of ionizing radiation on admittance measurements of Au/TiO2/n-Si (MIS) capacitor

This study aimed to investigate the influence of ionizing radiation on the admittance measurements of Titanium dioxide (TiO2)-based metal-insulator-semiconductor (MIS) capacitor. The capacitor was irradiated to a cumulative dose of 100 kGy using a 60Co-gamma (γ) source. The electrical admittance (Y = G + iωC) measurements of the MIS capacitor were performed before and after exposure to gamma irradiation for four different frequencies (1, 10, 100 and 500 kHz). Gamma irradiation leads to changes in the capacitance/conductance versus voltage (C/G–V) characteristics. The C and G showed a decrease by increasing the radiation dose and frequency. This decrease is attributed to the interface traps and oxide-trapped charges created during the gamma irradiation. The obtained results showed that the prepared MIS capacitor have great potential for dosimetry applications.

Synthesis, characterization and thermoluminescence of MgO:Li,Tb,Sm phosphor for high dose gamma dosimetry applications

A detailed TL investigation on MgO:Li,Tb,Sm phosphor has been carried out by studying several TL characteristics - TL glow curve structure, dose response, linearity dose behavior, fading and reproducibility. TL glow curve structure of the phosphor reveals the presence of two TL glow peaks. The main TL glow peak of high intensity is observed at high temperature side i.e. at 162 °C and another peak of low intensity is observed at 316 °C. Further, the effect of dose on TL response of the phosphor has been studied and a new behavior is noticed. With increasing doses, the position of main TL glow peak is similar while the second TL glow peak vanishes at higher doses. A linear TL response is observed from 10 Gy–700 Gy and becomes sublinear above 700 Gy. Low TL fading characteristics and good reproducibility have also been observed. Encouraging results suggest the applicability of doped MgO phosphor for the detection of gamma rays.