ORCID Profile
0000-0001-5793-9236
Current Organisation
Universiti Malaya
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Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1016/J.APRADISO.2015.08.025
Abstract: Over the past decade and more, considerable interest has been shown in the thermoluminescence (TL) properties of silica-based single-mode optical fibres, in particular investigating potential ionising radiation dosimetry applications. Herein, study has been made of TL glow curve, dose response, reproducibility and fading of 6mol% Ge-doped silica, fabricated in-house and produced in the form of cylindrical fibres. Three different pairings of doped-core and silica cladding diameters were produced: (40, 241)µm, (80, 483)µm and (100, 604)µm. The TL results were compared against that of TLD-100, one of the most sensitive commercially available LiF-based TL media. For all three pairings of diameters, closely similar TL glow curve were obtained, formed of a single peaked structure with a maximum TL yield located between the temperatures 250 and 310°C. The TL yield of the fibres were linear over the range of doses investigated, from 1Gy up to 10Gy, their dose response exceeding that of TLD-100, the s les also being found to be reusable, without evidence of degradation.
Publisher: IOP Publishing
Date: 31-08-2017
Abstract: The sensitivity of a novel silica-based fibre-form thermoluminescence dosimeter was tested off-site of a rare-earths processing plant, investigating the potential for obtaining baseline measurements of naturally occurring radioactive materials. The dosimeter, a Ge-doped collapsed photonic crystal fibre (PCFc) co-doped with B, was calibrated against commercially available thermoluminescent dosimetry (TLD) (TLD-200 and TLD-100) using a bremsstrahlung (tube-based) x-ray source. Eight s ling sites within 1 to 20 km of the perimeter of the rare-earth facility were identified, the TLDs (silica- as well as TLD-200 and TLD-100) in each case being buried within the soil at fixed depth, allowing measurements to be obtained, in this case for protracted periods of exposure of between two to eight months. The values of the dose were then compared against values projected on the basis of radioactivity measurements of the associated soils, obtained via high-purity germanium gamma-ray spectrometry. Accord was found in relative terms between the TL evaluations at each site and the associated spectroscopic results. Thus said, in absolute terms, the TL evaluated doses were typically less than those derived from gamma-ray spectroscopy, by ∼50% in the case of PCFc-Ge. Gamma spectrometry analysis typically provided an upper limit to the projected dose, and the Marinelli beaker contents were formed from sieving to provide a homogenous well-packed medium. However, with the radioactivity per unit mass typically greater for smaller particles, with preferential adsorption on the surface and the surface area per unit volume increasing with decrease in radius, this made for an elevated dose estimate. Prevailing concentrations of key naturally occurring radionuclides in soil,
Publisher: Springer Science and Business Media LLC
Date: 27-05-2020
Publisher: Elsevier BV
Date: 03-2020
Publisher: Elsevier BV
Date: 11-2016
DOI: 10.1016/J.APRADISO.2015.12.034
Abstract: Using irradiated doped-silica preforms from which fibres for thermoluminescence dosimetry applications can be fabricated we have carried out a range of luminescence studies, the TL yield of the fibre systems offering many advantages over conventional passive dosimetry types. In this paper we investigate such media, showing emission spectra for irradiated preforms and the TL response of glass beads following irradiation to an
Publisher: Elsevier BV
Date: 02-2020
Publisher: Trans Tech Publications, Ltd.
Date: 2016
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1133.409
Abstract: Thermoluminescence (TL) characteristics for various cross-sections of 6 mole% of tailor-made Ge-doped cylindrical optical fibers were determined. The general TL characteristic i.e., dose rate dependence, energy dependence, dose response and reproducibility of the s les have been investigated. The s les were irradiated using electron beam (Linac) and been exposed to dose ranging from 1 to 4 Gy. The cylindrical optical fibers provide highly linear dose response within the clinical relevant dose range, independence of radiation energy over the range of energies investigated, independence of dose rate and excellent reproducibility. This research shows that germanium doped silica fibers have high potential of dosimetric properties and suitable as TL-mode detectors in instances of radiotherapy (clinical dosimetry).
Publisher: Elsevier BV
Date: 11-2017
Publisher: Trans Tech Publications, Ltd.
Date: 2016
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1133.434
Abstract: We have investigated the suitability of 8% mole of tailor-made germanium (Ge)- doped silica (Si0 2 ) cylindrical fibers to use as the detector, to map dose that received by the patient during the treatment especially for X-ray radiation. The diameters of these cylindrical optical fibers are 362μm, 483μm and 604μm with different in masses and have been supplied by Telekom Malaysia (TM) group. To study the thermoluminescence reponse of these fibers, X-ray source with 60 kVp, 80 kVp and 100 kVp were used to irradiate the s les. The dosage of X-ray source was measured by the calibrated ionization chamber. The potential of these (Ge) - doped silica (Si0 2 ) cylindrical fibers as an efficient thermoluminescence (TL) material was investigated comparing the thermoluminescence response of the fibers with standard TLD 100. In confronting the variation of the dopant concentration (Germanium) along the core of the optical fibers, the in idual calibrations so called as Elemental Correction Coefficient (ECC) were carried out. The results showed that, the best annealing temperature and time (to erase the previous signal) for the s les are 400 °C for one hour. The TL Yield (measured in counts per second per unit mass of fiber) increases as the dose of X-ray beams increases from 0.08 Gy up until 2.8 Gy. The results were clearly indicated that the TL response of SiO 2 fibers were energy dependent. It can be concluded that, Ge-doped optical Silica (SiO 2 ) optical fibers is very suitable to use as TLD to measure dose in medical applications.
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.APRADISO.2019.04.001
Abstract: Study has been made of the thermoluminescence (TL) yield of various glass-based commercial kitchenware (Reko-China, Skoja-France, Godis-China, Glass Tum-Malaysia, Lodrat-France). Interest focuses on their potential for retrospective dosimetry. Use was made of a
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.APRADISO.2019.02.016
Abstract: We explore the utility of controlled low-doses (0.2-100 Gy) of photon irradiation as initiators of structural alteration in carbon-rich materials. To-date our work on carbon has focused on β-, x- and γ-irradiations and the monitoring of radiotherapeutic doses (from a few Gy up to some tens of Gy) on the basis of the thermoluminescence (TL) signal, also via Raman and X-ray photo-spectroscopy (XPS), providing analysis of the dose dependence of single-walled carbon nanotubes (SWCNT). The work has been extended herein to investigate possibilities for analysis of structural alterations in graphite-rich mixtures, use being made of two grades of graphite-rich pencil lead, 8H and 2B, both being in the form produced for mechanical pencils (propelling or clutch pencils). 2B has the greater graphite content (approaching 98 wt %), 8H being a mixture of C, O, Al and Si (with respective weight percentages 39.2, 38.2, 9.8 and 12.8). Working on media pre-annealed at 400 °C, both have subsequently been irradiated to penetrating photon-mediated doses. Raman spectroscopy analysis has been carried out using a 532 nm laser Raman spectrometer, while for s les irradiated to doses from 1 to 40 Gy, XPS spectra were acquired using Al K
Publisher: Elsevier BV
Date: 08-2017
Publisher: MDPI AG
Date: 13-10-2020
DOI: 10.3390/APP10207127
Abstract: Cars of a variety of brands are usually parked at a fixed but increasing distance in the periphery of nuclear installations. Herein we focus on the potential use of car windscreens for post-accident dose reconstruction from unplanned nuclear events and natural disasters, also in regard to unexpected events arising during large-scale use of radioactive and nuclear materials. The situation requires identification of analytical techniques that could both readily and reliably be used to assess absorbed dose, sufficient to prompt remedial action where necessary. S les from three widely used car brands—Honda, Toyota and Proton—are studied in respect of their thermoluminescence (TL) yield. Key TL dosimetric features in the gamma-ray dose range of 1–100 Gy are examined. An ERESCO model 200 MF4-RW X-ray machine has also been used for energy response studies a Harshaw 3500 TLD reader equipped with WinREMS software was used for the luminescence measurements. All brands exhibit linearity of TL yield versus dose, the s les from Honda showing the greatest response followed by that of the Toyota and Proton brands. The marked energy dependence reflects the effect of the strongly Z-dependent photoelectric effect. Signal fading was investigated over a period of 28 days, the Toyota and Proton brand windshield glass showing a relatively low loss at 52.1% and 52.6% respectively compared to a 56.7% loss for that of the Honda s les. This work forms the first such demonstration of the potential of car windshield glass as a retrospective accident dosimeter.
Publisher: Elsevier BV
Date: 09-2019
DOI: 10.1016/J.APRADISO.2019.04.027
Abstract: Present research concerns the TL signal stored in chalk of the variety commercially available for writing on blackboards. S les of this have been subjected to x-ray irradiation, the key dosimetric parameters investigated including dose and energy response, sensitivity, fading and glow curve analysis. Three types of chalk have been investigated, each in five different colours. The s les were annealed at 323 K prior to irradiation. For all three chalk types and all five colours, the dose response has been found linear over the investigated dose range, 0-9 Gy. Regardless of type or colour, photoelectric energy dependency is apparent at the low energy end down to the lowest investigated accelerating potential of 30 kV. Crayola (Yellow) has shown the greatest TL sensitivity, thus selection has been made to limit further analysis to this medium alone, specifically in respect of glow curve and fading study. In addition, elemental compositional and structural change characterizations were made for the same medium, utilizing Energy Dispersive X-Ray (EDX) and Raman spectroscopy, respectively.
Publisher: Elsevier BV
Date: 08-2017
No related grants have been discovered for siti fairus abdul sani.