Radio-photoluminescence properties of LiCaAlF6: Sm

Radiation Measurements

Published On 2020/3/1

In this paper, we report radio-photoluminescence (RPL) properties of Sm-doped LiCaAlF6 as a new RPL material. The material was successfully synthesized via the mechanochemical route by mixing LiF, CaF2, AlF3, and SmF3 raw powders in a planetary ball-mill. The resulting powder sample shows photoluminescence (PL) predominantly due to the 4f-4f transitions of Sm3+, indicating that the doped Sm ion is optically activated. After irradiating with X-rays, additional PL emissions appeared around 700 nm; that is, Sm-doped LiCaAlF6 exhibits RPL properties. From the spectral features and luminescence dynamics, the origin of the RPL centre is determined to be the 4f-4f transitions of Sm2+. Therefore, in this material system, intra-valence change of Sm ion (Sm3+ → Sm2+) is induced by X-ray irradiation. Furthermore, using an elementary detector and the RPL signal, we could detect signals under a dose as low as …

Journal

Radiation Measurements

Published On

2020/3/1

Volume

132

Page

106251

Authors

Safa Kasap

Safa Kasap

University of Saskatchewan

Position

Professor of Electrical Engineering

H-Index(all)

49

H-Index(since 2020)

29

I-10 Index(all)

0

I-10 Index(since 2020)

0

Citation(all)

0

Citation(since 2020)

0

Cited By

0

Research Interests

electronic materials

optoelectronic and photonic materials

devices

detectors

photoconductors

University Profile Page

Hidehito Nanto

Hidehito Nanto

Kanazawa Institute of Technology

Position

H-Index(all)

44

H-Index(since 2020)

19

I-10 Index(all)

0

I-10 Index(since 2020)

0

Citation(all)

0

Citation(since 2020)

0

Cited By

0

Research Interests

Odor sensor

Dosimeter

Thin films

University Profile Page

Go Okada

Go Okada

Kanazawa Institute of Technology

Position

H-Index(all)

33

H-Index(since 2020)

28

I-10 Index(all)

0

I-10 Index(since 2020)

0

Citation(all)

0

Citation(since 2020)

0

Cited By

0

Research Interests

Optoelectronics

Dosimetry

X-ray Imaging

Phosphor

University Profile Page

Other Articles from authors

Safa Kasap

Safa Kasap

University of Saskatchewan

Journal of Materials Science: Materials in Electronics

29 December 2023 Professor Patrick McNally Dublin City University, Ireland Former Deputy Editor-in-Chief

With much sadness, we announce the passing away of Professor Patrick McNally, who unexpectedly left us on December 29, 2023. Professor McNally was an editorial member, Editor and then the Deputy Editor-in-Chief of this journal for 20+ years. He was much liked and much respected by his colleagues in the journal and served the scientific publishing community with high-spirited enthusiasm and unselfish dedication. As the Deputy Chief Editor, he had to deal with numerous misconduct and fraudulent data complaints. He investigated each with utmost integrity and did not leave any stone unturned until he arrived at a just decision, even if it meant retracting a paper. We all trusted his judgement and we all appreciated the endless time and effort he put into maintaining the journal’s high standards. He became a role model to new editors. Professor McNally also promoted the involvement of more women in …

Safa Kasap

Safa Kasap

University of Saskatchewan

Journal of Medical Imaging

Improved temporal performance and optical quantum efficiency of avalanche amorphous selenium for low dose medical imaging

PurposeActive matrix flat panel imagers (AMFPIs) with thin-film transistor arrays experience image quality degradation by electronic noise in low-dose radiography and fluoroscopy. One potential solution is to overcome electronic noise using avalanche gain in an amorphous selenium (a-Se) (HARP) photoconductor in indirect AMFPI. In this work, we aim to improve temporal performance of HARP using a novel composite hole blocking layer (HBL) structure and increase optical quantum efficiency (OQE) to CsI:Tl scintillators by tellurium (Te) doping.ApproachTwo different HARP structures were fabricated: Composite HBL samples and Te-doped samples. Dark current and optical sensitivity measurements were performed on the composite HBL samples to evaluate avalanche gain and temporal performance. The OQE and temporal performance of the Te-doped samples were characterized by optical sensitivity …

Hidehito Nanto

Hidehito Nanto

Kanazawa Institute of Technology

Journal of Alloys and Compounds

Radiophotoluminescence properties of Bi-doped NaCaBO3

Bi-doped NaCaBO3 exhibits radiophotoluminescence (RPL) properties, where the Bi2+ centre is formed through X-ray irradiation. As a result of RPL, a broad emission band appears around 800 nm in the photoluminescence (PL) spectrum, attributed to X-ray irradiation. The intensity of the PL signal is proportional to the irradiation dose, making it useful for measuring accumulated radiation dose. The sensitivity depends on the doping concentration of Bi, and the optimal concentration to maximize sensitivity is approximately 0.005%. With a laboratory-constructed reader system, the optimal sample enables measurement of X-ray dose as low as 25 mGy. Following irradiation, the Bi2+ signal slightly increases by about 13%, but it is significantly reduced to around 7% of the initial value after heat treatment at 500°C for 100 s. The formation and annihilation of the Bi2+ centre can be reproduced multiple times. Therefore …

Hidehito Nanto

Hidehito Nanto

Kanazawa Institute of Technology

Sensors and Materials

Radio-photoluminescence Properties of Eu-doped CaBPO5

Eu-doped CaBPO5 was synthesized by the solid-state reaction route, and then its radiophotoluminescence properties were studied. On the basis of steady-state and time-resolved photoluminescence (PL) studies, it was confirmed that Eu2+ is formed by X-ray irradiation due to the valence change of the Eu ion (Eu3+→ Eu2+). In addition, for dosimetric applications, it was demonstrated that the PL intensity of Eu2+ is proportional to the accumulated radiation dose, is stable after irradiation, and can be reversed by heat treatment at 500℃ for 100 s.

Go Okada

Go Okada

Kanazawa Institute of Technology

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Photoluminescence, scintillation, and TSL properties of Dy-doped BaCaBO3F

We fabricated BaCaBO3F (BCBF) with various Dy concentrations (0.1 %, 1 %, and 5 %), and evaluated the luminescence properties for radiation dosimetry. Sharp scintillation peaks originating from the 4f → 4f transition of Dy3+ were observed. Furthermore, thermally stimulated luminescence (TSL) glow curves were recorded, and a TSL glow peak at approximately 120 °C was observed. The 0.1 % Dy-doped BCBF exhibited the highest TSL intensity, and dose response curves of the 0.1–1 % Dy-doped BCBF were obtained in the 0.1–10000 mGy range. Moreover, at least seven activation energy levels related to TSL were confirmed by the TSL isothermal decay analysis.

Go Okada

Go Okada

Kanazawa Institute of Technology

Optik

Effect of Al-doping on dosimetric properties of CaF2

In this study, the effect of Al-doping on dosimetric properties of CaF2 was investigated. Al-doped CaF2 showed a radiophotoluminescence (RPL) peak at 750 nm after X-ray irradiation. The RPL intensity decreased with the increase of Al concentration and was less than that of undoped CaF2. The minimum detectable dose as the RPL dosimeter of 0.01% Al-doped CaF2 was 42 mGy. Al-doped CaF2 also indicated thermally stimulated luminescence (TSL) glow peaks at 225, 285, 387, and 436 °C. The wavelengths of TSL were 390 and 500 nm. The minimum detectable dose as the TSL dosimeter of 1% Al-doped CaF2 turned out to be 0.43 μGy which is comparable to commercial dosimeters.

Go Okada

Go Okada

Kanazawa Institute of Technology

Journal of Luminescence

Investigation of radio-photoluminescence properties in Sm-doped Al4SiO8 single crystals

We report radio-photoluminescence (RPL) properties of Sm-doped Al4SiO8 single crystals as a new RPL material. The Sm-doped Al4SiO8 single crystals were synthesized by the floating zone method. In PL emission spectra, the emission peaks due to the 4f-4f transitions of Sm3+ ions and 2EJ–4A2 transitions of Cr3+ ions were observed before X-ray irradiation, and the ones due to the 4f-4f transitions of Sm2+ appeared as well as Sm3+ after X-ray irradiation. The RPL dose response functions showed linear response from 1 mGy to 10 Gy for the 2.0% Sm-doped sample and from 10 mGy to 10 Gy for the others. Sm2+ ions of the new emission center completely disappeared by heat treatment at 500 °C for 10 min.

Go Okada

Go Okada

Kanazawa Institute of Technology

Journal of Materials Science: Materials in Electronics

Thermoluminescence response of a BeO ceramic dosimeter in therapeutic proton beam

BeO ceramics (Thermalox® 995, Materion Corp.) can function as thermoluminescent dosimeters (TLDs) with a tissue-equivalent effective atomic number and sufficient high solidity which can be used as postal dosimeters. To evaluate the feasibility of employing BeO ceramic in proton dosimetry, we investigated the dose–response and the linear energy transfer (LET) dependence of a BeO ceramic TLD. As the BeO ceramic TLDs exhibit two glow peaks, the dose–responses of the integral thermoluminescence (TL) signals for the low-temperature (GL) and high-temperature (GH) glow peaks, as well as those for entire TL signal (GT), were all investigated in this study. The irradiation doses were 0.5, 1.0, 2.0, and 5.0 Gy, and the LET dependence of the TL efficiency was investigated between 0.53 and 7.42 keVµm−1. All experiments were performed using a 160 MeV proton beam at NIRS-HIMAC in Japan. The TL …

Go Okada

Go Okada

Kanazawa Institute of Technology

Materials Research Bulletin

X-ray induced reduction of Sm3+ into Sm2+ in Li2CaSiO4 and its potential for radiation measurement applications

In Sm3+-doped Li2CaSiO4, the Sm3+ ion is reduced to the Sm2+ state by X-ray irradiation. The valence change was confirmed by the difference in their photoluminescence spectra, measured before and after irradiation. Only luminescence peaks due to the 4f-4f transitions of Sm3+ are observed before the irradiation while an additional luminescence band is observed at 900 nm due to the 5d-4f transition of Sm2+. The reaction is that a fraction of X-ray generated electrons is captured by Sm3+ ions, which convert to the Sm2+ state. The generated Sm2+ state is fairly stable while it is effectively reversed back to the Sm3+ state by a heat treatment at an elevated temperature. A numerical approximation revealed the activation energy to be 0.40 and 0.52 eV. Even after the heat-treatment, the reduction of Sm3+ to Sm2+ is reproducible multiple times, which shows good potential for using radiation measurement applications.

Go Okada

Go Okada

Kanazawa Institute of Technology

Radiation Physics and Chemistry

Optically stimulated luminescence of K2SO4: Ce and its relationship with TL glow-curves

K2SO4:Ce was investigated with respect to its OSL and TL properties. Due to the doping with Ce3+ ions, the material shows strong emission in the range of 300–400 nm with a maximum of approx. 330 nm. The spectrum of OSL stimulation is wide and enables stimulation with visible light and infrared. When comparing the 550 nm and 900 nm stimulation, differences in the initial intensity, decay rate and total counts can be seen. The higher total counts are obtained for 550 nm green light, with the initial intensity being higher for 900 nm infrared. The OSL signal, for both stimulations, is sensitive to preheat, however, this relationship is different in both cases. The study of the mutual correlation of the TL and OSL signal showed that only a part of the peaks in the TL curve are bleached by optical stimulation. The result indicates that there are both optically active and non-optically active traps in the material. The OSL-TL …

Hidehito Nanto

Hidehito Nanto

Kanazawa Institute of Technology

Japanese Journal of Applied Physics

Radiophotoluminescence properties of Eu-doped Li2SrSiO4 for radiation detectors

To search for new radiophotoluminescence (RPL) materials, Eu-doped Li 2 SrSiO 4 was synthesized by the solid-state reaction and then studied its RPL properties for radiation detector applications. All the samples were identified to be Li 2 SrSiO 4 by X-ray diffraction. The as-prepared sample shows photoluminescence (PL) due to Eu 3+ while an additional PL band appears due to a formation of Eu 2+ after X-ray irradiation. This indicates that the Eu-doped Li 2 SrSiO 4 has RPL properties. The sensitivity of RPL (or PL intensity of Eu 2+) to X-ray dose is the highest when the Eu concentration is 0.1%, and the dynamic range is 5–10 000 mGy. In addition, the generated Eu 2+ is so stable that only 5% of the signal degrades over 20 min after irradiation. The RPL signal notably decreases to about 30% of the initial value by heating at 500 C for 100 s, and it is reproducible multiple times even after the heat treatment.

2023/12/20

Article Details
Hidehito Nanto

Hidehito Nanto

Kanazawa Institute of Technology

Journal of Materials Science: Materials in Electronics

ESR studies to elucidate the origin of the RPL emission of undoped-CaSO4

Recent research has shown that CaSO4, without any intentional addition of impurities, exhibits remarkable radiophotoluminescence (RPL) properties. However, the origin of the RPL in CaSO4 has yet to be fully understood. ESR measurements were carried out to identify the defect species responsible for RPL and elucidate the luminescence’s origin. ESR measurements on undoped-CaSO4 with different radiation sensitivities showed SO4−, SO2−+SO3−, PO42−, Si=O3 in P2O5–SiO2 (E’ center), Al2O3 hole center and Mn2+ defect species in CaSO4. This means that CaSO4 contains Al2O3, Mn2+, P, and Si as impurities, which are not intentionally added to CaSO4. As the results of this study, the different impurity states may influence the radiation sensitivity of the materials. It is suggested that the deliberate addition of P and Si elements, Al2O3 and Mn2+ could control the RPL properties.

Hidehito Nanto

Hidehito Nanto

Kanazawa Institute of Technology

Materials Research Bulletin

X-ray induced reduction of Sm3+ into Sm2+ in Li2CaSiO4 and its potential for radiation measurement applications

In Sm3+-doped Li2CaSiO4, the Sm3+ ion is reduced to the Sm2+ state by X-ray irradiation. The valence change was confirmed by the difference in their photoluminescence spectra, measured before and after irradiation. Only luminescence peaks due to the 4f-4f transitions of Sm3+ are observed before the irradiation while an additional luminescence band is observed at 900 nm due to the 5d-4f transition of Sm2+. The reaction is that a fraction of X-ray generated electrons is captured by Sm3+ ions, which convert to the Sm2+ state. The generated Sm2+ state is fairly stable while it is effectively reversed back to the Sm3+ state by a heat treatment at an elevated temperature. A numerical approximation revealed the activation energy to be 0.40 and 0.52 eV. Even after the heat-treatment, the reduction of Sm3+ to Sm2+ is reproducible multiple times, which shows good potential for using radiation measurement applications.

Hidehito Nanto

Hidehito Nanto

Kanazawa Institute of Technology

Journal of Materials Science: Materials in Electronics

Radio-photoluminescence properties of Eu-doped SrAl2O4 ceramics and thermally assisted charge transfer process

Radio-photoluminescence (RPL) properties of Eu-doped SrAl2O4 are studied focusing on the generation of a luminescent center by ionizing radiation of X-ray and its extinction by a thermally assisted charge transfer. The single phases of SrAl2O4 doped with Eu at concentrations of 0.05–1.0% are synthesized via solid-state reactions, as confirmed by X-ray diffractions analyses. They show photoluminescence (PL) due to both Eu3+ and Eu2+, and the PL intensity due to Eu3+ decreases after X-ray irradiation while the one due to Eu2+ notably increases. This indicates that Eu2+ as a luminescence center is generated as RPL through reduction from Eu3+ to Eu2+ by ionizing radiation of X-ray. Particularly, the 0.1% Eu-doped sample shows the highest sensitivity to X-ray dose, and the lowest detection limit is estimated to be 0.3 Gy with the present reader system. The RPL signal is reasonably stable, and it depends on …

Safa Kasap

Safa Kasap

University of Saskatchewan

Journal of Luminescence

The effect of excited-state absorption on up-conversion photoluminescence behavior in erbium-ion doped gallium lanthanum sulphide-oxide glasses

Abstract Photoluminescence (PL) of Er 3+ ions embedded in GaLaS (O) glass at excitation wavelengths of 488, 532, 660, 808, and 980 nm has been studied. Typical cases at which the ratios of the optical transition intensities have no dependence on the pumping intensity have been considered. For the case of pumping at the 488 nm wavelength the method of extrapolation coefficients, which reveals the up-conversion nature of PL “mimicking” a “normal” PL, has been demonstrated. The thermal coupling of S 3/2 4 and H 11/2 2 manifolds, which are responsible for the intense PL in the green region of the visible spectral range, is discussed.

Go Okada

Go Okada

Kanazawa Institute of Technology

Journal of Alloys and Compounds

Ce concentration dependence on scintillation properties of SrHfO3 single crystals

Transparent and yellowish Ce-doped SrHfO3 (Ce:SHO) single crystals were grown by the xenon lamp equipped floating zone method. The synthesized crystals were in the single phase of SHO crystal structure, and no impurity phases such as HfO2 were evident by the X-ray diffraction analysis. The Ce:SHO shows blue luminescence peaking at 410 nm in both the PL and scintillation spectra, and the decay time constant was approximately 14 ns. The PL QY increases with the Ce concentration, which was confirmed up to 5%. The afterglow level is the lowest when the Ce concentration is 3%. The full energy peak can be demonstrated with all the Ce:SHO single crystals prepared in this study under 241Am alpha-ray irradiation, and the estimated light yield is 396 photons/MeV for the 3% Ce:SHO, which is the highest among the samples studied.

Go Okada

Go Okada

Kanazawa Institute of Technology

Ceramics International

Optical and photostimulated luminescence properties of Eu: BaFBr translucent ceramics synthesized by SPS

Eu:BaFBr translucent ceramics were synthesized by the spark plasma sintering method, and then the crystal structure, optical and photostimulated luminescence (PSL) properties were investigated. The synthesized 0.05–0.5% Eu:BaFBr are translucent, and the optical transmittance is 30–50%. The photoluminescence and PSL spectra consist of an emission band peaking around 390 nm due to the presence of Eu2+ ion. The photoluminescence quantum yield and the sensitivity of PSL to X-rays are the highest when the doping concentration is 0.5%, and they are higher than those of the commercial Eu:BaFBr imaging plate (IP). In addition, the spatial resolution of an X-ray image obtained by using the 0.5% Eu:BaFBr translucent ceramic as an imaging plate is higher than the one obtained by using the commercial IP.

Safa Kasap

Safa Kasap

University of Saskatchewan

Materials Research Bulletin

X-ray induced reduction of Sm3+ into Sm2+ in Li2CaSiO4 and its potential for radiation measurement applications

In Sm3+-doped Li2CaSiO4, the Sm3+ ion is reduced to the Sm2+ state by X-ray irradiation. The valence change was confirmed by the difference in their photoluminescence spectra, measured before and after irradiation. Only luminescence peaks due to the 4f-4f transitions of Sm3+ are observed before the irradiation while an additional luminescence band is observed at 900 nm due to the 5d-4f transition of Sm2+. The reaction is that a fraction of X-ray generated electrons is captured by Sm3+ ions, which convert to the Sm2+ state. The generated Sm2+ state is fairly stable while it is effectively reversed back to the Sm3+ state by a heat treatment at an elevated temperature. A numerical approximation revealed the activation energy to be 0.40 and 0.52 eV. Even after the heat-treatment, the reduction of Sm3+ to Sm2+ is reproducible multiple times, which shows good potential for using radiation measurement applications.

Go Okada

Go Okada

Kanazawa Institute of Technology

Materials Research Bulletin

Scintillation and dosimeter properties of Pr2O3-doped Ga2O3–K2O–La2O3 glasses

Rare-earth-activated glasses have attracted research attention for radiation measurements for decades because of several practical merits, including their amenability towards mass production, large-volume fabrication, easing shaping, and their low cost. Various glass materials (e.g., borate and silicate glasses) have been characterized. In this study, photoluminescence, scintillation, and thermally stimulated luminescence (TSL) characteristics were observed for Pr3+-activated gallate glasses (69Ga2O3–20K2O–(11-x)La2O3–xPr2O3). Clear photoluminescence and scintillation peaks derived from the 4f-4f transitions of Pr3+ appeared in the range of 480–670 nm, where the photoluminescence and scintillation decay time constants attributable to the 4f-4f transitions of Pr3+ were on the order of microseconds. The thermoluminescence of these glasses was also investigated, where a broad TSL glow peak was …

Go Okada

Go Okada

Kanazawa Institute of Technology

Radiation Measurements

Optically stimulated luminescence characteristics and dosimetric properties of copper-doped potassium sulphate

Optically Stimulated Luminescence (OSL) properties of the sol-gel synthesized nano-powders of Beryllium Oxide (BeO) were investigated. Luminescence properties of BeO nanoparticles are dependent on the crystal structure, particle size, and morphology and therefore strongly dependent on the way of synthesis, thus the preparation was modified to enhance the OSL signal from the material. Structural, thermal and morphological properties of BeO in nanopowder and pellet forms were studied using X-Ray Diffraction (XRD), Fourier Transform Infrared Microscopy (FTIR), Simultaneous Thermal Analysis STA (Thermo Gravimetric Analysis (TGA)/Differential Scanning Calorimetry (DSC)) and Scanning Electronic Microscopy (SEM) techniques. XRD and STA analysis suggested an enhancement in crystallinity and thermal stability of the BeO with increasing sintering temperature.OSL dosimetric properties of the pellets …

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Radiation Measurements

Optically-stimulated luminescence and thermoluminescence properties of RbI: Eu single crystals

This paper presents a preliminary characterization of the optically stimulated luminescence (OSL) and thermoluminescence (TL) properties of terbium-doped samples as potential new OSL dosimeters. The samples include lithium aluminate (LiAlO2:Tb, Li2Al2O4:Tb), magnesium silicate (Mg2SiO4:Tb, Mg2SiO4:Tb,Co) and calcium silicate (CaSiO3:Tb). The OSL and TL emission spectra show the characteristic lines of Tb3+. The OSL intensity of the most sensitive samples is one order of magnitude lower than Al2O3:C. Nevertheless, the sensitivity and dose response are suitable for dosimetry applications, with the lower limit of detection estimated to be in the range from ∼30–50 to ∼200μGy, depending on the sample. The OSL response is linear over the range of doses investigated, from 2mGy to 5Gy, except for CaSiO3:Tb samples. OSL stimulation spectra show that blue light (470nm) is six times more efficient than …

Joel Q.G. Spencer

Joel Q.G. Spencer

Kansas State University

Radiation Measurements

Testing emergency radiation doses by metastable TL peaks in quartz− preliminary investigations

In the case of nuclear or radiological emergencies, rapid examination of individuals from affected areas is necessary. The limited capacity of existing laboratories and dosimetric methods requires narrowing down, using short−term emergency dosimetry, the areas in which people should be examined first. Quartz, the abundant mineral widely used in dating and luminescence retrospective dosimetry, is an obvious candidate for a dosimeter in such cases. Until now, most dose reconstruction studies using quartz from buildings, structures and ceramics have used high−temperature thermoluminescence (TL) or optically stimulated luminescence (OSL) from relatively stable trapping systems. The separation of residual signals from long−term exposure to natural radioactivity and time−consuming measurement sequences is an issue with the high−temperature methods. While less explored for dose reconstruction, the TL …

Xiaobin Tang(汤晓斌)

Xiaobin Tang(汤晓斌)

Nanjing University of Aeronautics and Astronautics

Radiation Measurements

Advancing 2D Reaction Rate Measurements in BNCT: Validation of the Indirect Neutron Radiography Method

The precise characterization of neutron beams is a cornerstone of Boron Neutron Capture Therapy (BNCT). While Instrumental Neutron Activation Analysis (INAA) is the standard technique for neutron flux measurement, it is limited in its ability to capture two-dimensional (2D) reaction rate distributions. This study aims to validate the Indirect Neutron Radiography (INR) method for 2D reaction rate quantification, addressing critical variables such as temperature sensitivity and signal fading. We engineered an optimized INR platform comprising an Imaging Plate (IP), readout device, activation detectors (copper foils), and real-time temperature monitoring. Comprehensive experiments were conducted to investigate the impact of ambient temperature and fading time on IP signal reliability. A robust calibration curve was formulated, linking IP signals to dose deposition metrics, thereby enabling precise reaction rate …

Juergen debus

Juergen debus

Heidelberg University

Radiation Measurements

Characterisation of a customised 4-chip Timepix3 module for charged-particle tracking

Ion-beam radiotherapy is a growing cancer treatment modality because it offers a superior dose distribution in the patient compared with conventional radiotherapy using X-rays. Thanks to their versatility, application-specific integrated circuits (ASIC) increasingly gain interest for research into ion imaging and ion-beam characterisation. Timepix3 is a hybrid semiconductor pixel detector, which offers nanosecond time binning as well as dead-time-free and noise-free data-driven readout at a pixel pitch of 55 µm × 55 µm. In this work, a novel 4-chip Timepix3 mini-tracker (quad module) was characterised in a therapeutic proton beam. The quad module has two detection layers equipped with two Timepix3 chips each, which are stacked like a particle telescope at a distance of 20.3 mm. In a detection layer, two Timepix3 chips share the same sensitive silicon sensor. The surface area of the silicon sensor is approximately …

Osman Vefa Gul

Osman Vefa Gul

Selçuk Üniversitesi

Radiation Measurements

Investigation of skin dose of post-mastectomy radiation therapy for the halcyon and tomotherapy treatment machine: Comparison of calculation and in vivo measurements

In treatments such as post-mastectomy radiation therapy (PMRT) for breast cancer patients, skin doses are of great importance in terms of tumor control and side effects. This dosimetric study aimed to measure the skin dose on the chest wall surface for post-mastectomy radiotherapy with Tomotherapy and Halcyon devices using thermoluminescence dosimetry (TLD) and to evaluate the accuracy of the skin dose calculated by treatment planning systems (TPS). Computed tomography (CT) images of the Alderson Rando phantom were obtained. Treatment plans were created with Tomotherapy and Halycon devices for a total of 50 Gy with a fraction dose of 2 Gy to the target volume. The left chest wall was divided into 9 regions for detailed surface dose assessment. 88 dose measurement points were determined on the left chest wall. The phantom was irradiated separately in Halycon and Tomotherapy devices. In …

Geoff Duller

Geoff Duller

Aberystwyth University

Radiation Measurements

Chasing snails: Automating the processing of EMCCD images of luminescence from opercula

Opercula of the gastropod Bithynia tentaculata are composed of calcite, and are typically 2–4 mm in length. They emit a thermoluminescence (TL) signal that can be used for dose reconstruction, and spatially resolved TL data from them can be obtained using an electron multiplying charge coupled device (EMCCD). However, when multiple measurements are made of the same sample with imaging detectors such as the EMCCD, registering the different images is crucial so that when regions of interest (ROI) are defined they consistently relate to the same part of the specimen. Previous work on opercula has undertaken this registration by hand, but this is prohibitively time consuming and is also potentially prone to human error. An automated registration process is described, and its use is illustrated using a dose recovery experiment. Without registration more than half of the regions of interest defined across the …

Diyun Shu

Diyun Shu

Nanjing University of Aeronautics and Astronautics

Radiation Measurements

Advancing 2D Reaction Rate Measurements in BNCT: Validation of the Indirect Neutron Radiography Method

The precise characterization of neutron beams is a cornerstone of Boron Neutron Capture Therapy (BNCT). While Instrumental Neutron Activation Analysis (INAA) is the standard technique for neutron flux measurement, it is limited in its ability to capture two-dimensional (2D) reaction rate distributions. This study aims to validate the Indirect Neutron Radiography (INR) method for 2D reaction rate quantification, addressing critical variables such as temperature sensitivity and signal fading. We engineered an optimized INR platform comprising an Imaging Plate (IP), readout device, activation detectors (copper foils), and real-time temperature monitoring. Comprehensive experiments were conducted to investigate the impact of ambient temperature and fading time on IP signal reliability. A robust calibration curve was formulated, linking IP signals to dose deposition metrics, thereby enabling precise reaction rate …

Christoph Schmidt

Christoph Schmidt

Université de Lausanne

Radiation Measurements

Testing emergency radiation doses by metastable TL peaks in quartz− preliminary investigations

In the case of nuclear or radiological emergencies, rapid examination of individuals from affected areas is necessary. The limited capacity of existing laboratories and dosimetric methods requires narrowing down, using short−term emergency dosimetry, the areas in which people should be examined first. Quartz, the abundant mineral widely used in dating and luminescence retrospective dosimetry, is an obvious candidate for a dosimeter in such cases. Until now, most dose reconstruction studies using quartz from buildings, structures and ceramics have used high−temperature thermoluminescence (TL) or optically stimulated luminescence (OSL) from relatively stable trapping systems. The separation of residual signals from long−term exposure to natural radioactivity and time−consuming measurement sequences is an issue with the high−temperature methods. While less explored for dose reconstruction, the TL …

Hiroshi Yasuda

Hiroshi Yasuda

Hiroshima University

Radiation Measurements

Preliminary analyses of radiophotoluminescence centers in a recently developed Ag-doped alkali-phosphate glass (SAPANS)

The mechanism behind radiophotoluminescence (RPL) emission in Ag-doped alkali-phosphate glass remains unclear. To contribute to resolving this issue, the authors measured and analyzed the temporal change of electron spin/paramagnetic resonance (ESR) spectrum of a recently developed, weather-resistant RPL glass, named “SAPANS,” after irradiation with X-rays. As a result, a continuous gradual increase in Ag2+-derived signals was observed even at four weeks post-irradiation, which corresponded well with the time build-up pattern of the RPL of SAPANS. In contrast, the signals derived from phosphorous-oxygen-hole centers (POHC) rapidly decreased over a few days. The peaks of Ag0 and Ag2+ were not successfully separated from the ESR spectra because of the possible overlap of unidentified peaks, which implies a complex mechanism of RPL-center formation in Ag-doped alkali-phosphate glass …