60Co Gamma Research Articles

Effects of total ionizing dose on transient ionizing radiation upset sensitivity of 40–180 nm SRAMs

Effects of total ionizing dose (TID) on the transient radiation upset sensitivity of commercial static random access memories (SRAMs) were investigated. Commercial SRAMs of three technology nodes were irradiated with Co-60 gamma rays for total dose effects and with pulsed x rays generated using a “Chen-Guang” accelerator for doserate effects. It is shown that TID irradiation and the memory pattern written to the memory array during TID irradiation can substantially affect the transient radiation upset sensitivity of all the SRAMs. First, the memory pattern written to the memory array during TID irradiation is more sensitive to pulsed x rays for all SRAMs. Second, the variation in transient radiation upset sensitivity with total dose has different tendencies for different SRAMs, but the static power current increased with the increase in total dose for all SRAMs. The increase in static power current with total dose and the increasing sensitivity of the memory pattern during TID irradiation are caused by the increasing TID induced leakage current, which results in an asymmetric noise margin of individual memory cells.

Determination of shielding Effectiveness of Concretes with different Aggregate and cement composition

The shielding effectiveness of concretes with different aggregate and cement composition was determine by shielding Co-60 gamma radiation source at center for energy research and training (CERT), Ahmadu Bello University Zaria with block concretes that contain aggregate 5.00 mm, 10.00 mm and 15.00 mm respectively. A concrete with thickness of 0.0762 m with dimension of 0.30 m x 0.30 m was formed from each of the aggregates with equal volume of sharp sand and cement. The result revealed the calculated mean free path (MFP) with values within a range of (0.033 to 0.070) m for samples DG (Dangote) and BU (BUA), mass attenuation coefficient (MAC) and half value layer (HVL) values within a range of (1.9 to 2.75) x 10-3 m2/kg and (0.023 to 0.049) m respectively. This shows that samples DG1, DG2 and DG3 have better shielding ability due to its lower MAC, MFP and HVL compared to samples BU1, BU2 and BU3.

Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the KRISS, Republic of Korea and the BIPM in 60Co gamma radiation

Main textA new key comparison of the standards for air kerma of the Korea Research Institute of Standards and Science (KRISS), Republic of Korea, and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in March 2022. The comparison result, based on the calibration coefficients for two transfer chambers and expressed as a ratio of the KRISS and the BIPM standards for air kerma, is 1.0006 with a combined standard uncertainty of 1.8 parts in 103. The result agrees within the uncertainties with the direct comparison carried out in 2010. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the NMIJ, Japan and the BIPM in 60Co gamma radiation

Main textA new key comparison of the standards for air kerma of the National Metrology Institute of Japan (NMIJ), Japan, and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in February 2022. The comparison result, based on the calibration coefficients for two transfer chambers and expressed as a ratio of the NMIJ and the BIPM standards for air kerma, is 1.0013 with a combined standard uncertainty of 2.2 parts in 103. The result agrees within the uncertainties with the direct comparison carried out in 2012. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Enhancement of Acylcarnitine Levels in Small Intestine of Abdominal Irradiation Rats Might Relate to Fatty Acid β-Oxidation Pathway Disequilibration.

ObjectiveThis study aims to analyze the alteration of carnitine profile in the small intestine of abdominal irradiation-induced intestinal injury rats and explore the possible reason for the altered carnitine profile.MethodsThe abdomens of 15 male Sprague Dawley (SD) rats were irradiated with 0, 10, and 15 Gy of 60Co gamma rays. The carnitine profile in the small intestine and plasma samples of SD rats at 72 h after abdominal irradiated with 0 Gy or 10 Gy of 60Co gamma rays were measured by targeted metabolomics. The changes of fatty acid β-oxidation (FAO), including the expression of carnitine palmitoyltransferase 1 (CPT1) and acyl-CoA dehydrogenases, were analyzed in the small intestine samples of SD rats after exposed to 0, 10, and 15 Gy groups.ResultsThere were eleven acylcarnitines in the small intestine and fourteen acylcarnitines in the plasma of the rat model significantly enhanced, respectively (P < .05). The expression level and activity of CPT1 in the small intestine were remarkably increased (P < .05), and the activity of acyl-CoA dehydrogenase in the small intestine was noticeably reduced (P < .01) after abdominal irradiation.ConclusionThe enhanced acylcarnitine levels in the small intestine of abdominal irradiation rats might relate to the FAO pathway disequilibration.

Key comparison BIPM.RI(I)-K4 of the absorbed dose to water standards of the KRISS, Republic of Korea and the BIPM in 60Co gamma radiation

Main textA first key comparison of the standards for absorbed dose to water of the Korea Research Institute of Standards and Science (KRISS), Republic of Korea, and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in March 2022. The comparison result, based on the calibration coefficients for two transfer standards and evaluated as a ratio of the KRISS and the BIPM standards for absorbed dose to water, is 0.9986 with a combined standard uncertainty of 3.8 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Key comparison BIPM.RI(I)-K4 of the absorbed dose to water standards of the NIM, China and the BIPM in 60Co gamma radiation

Main textA key comparison of the standards for absorbed dose to water of the National Institute of Metrology (NIM), China, and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in December 2021. The comparison result, based on the calibration coefficients for four transfer standards and evaluated as a ratio of the NIM and the BIPM standards for absorbed dose to water, is 1.0027 with a combined standard uncertainty of 3.6 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Supplementary comparison CCRI(I)-S3 of standards for absorbed dose to water in 60Co gamma radiation at radiation processing dose levels

Main textA supplementary comparison of standards for absorbed dose to water in 60Co fields used for calibrations at radiation processing dose levels has been completed. Alanine dosimeters from the NIST and the NPL were used as transfer dosimeters and all participant irradiations were carried out in self-shielded irradiators. Irradiations were also carried out at the BIPM to allow direct comparison of dose ratios with the Key Comparison BIPM.RI(I)-K4. No significant difference was seen between the dose ratios obtained using the NPL and NIST alanine systems, no significant impact of mailing on dosimeter response was noted, and the adopted protocol limited any dose rate effects to the level of Type A uncertainties. The national standards of the participants are in agreement within the standard uncertainties, which are in the range from 1 to 2 parts in 102.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Gamma ray-induced effects on the properties of CsPbBr3 perovskite thin film

In the last two decades, the family of metal halide perovskites has received more attention in radiation detection applications. In this work, the radiation detection and dosimetric applicability of the CsPbBr3 thin film will be investigated. The impact of gamma irradiation on the structural, morphological, optical, and electrical properties of the CsPbBr3 thin film has been studied. The CsPbBr3 thin film was synthesized using a thermal evaporation deposition technique. The deposited thin films were exposed to different gamma-ray doses (0, 25, 50, 75, and 100 kGy) using a 60Co gamma source with an activity of 7.328 kGy/h. X-ray diffraction analysis of the thin films confirmed the orthorhombic crystal structure and also showed an increase in the crystalline and crystallite sizes, whereas the dislocation density and microstrain decreased as the gamma dose increased. Field-emission scanning electron microscopy results revealed that the surface morphology changed considerably due to gamma exposure. The optical properties exhibited a decreasing energy band gap value (from 2.35 to 2.14 eV) as the radiation dosage increased, which may have been due to the increasing crystallite size and induced defects. The photoluminescence (PL) peaks shifted toward longer wavelengths and intensity, while the full width half maxima of PL peaks increased along with the gamma dose, which was attributed to spectral broadening and enhancement in the recombination rate of electron–hole pairs. Impedance spectroscopy of all the irradiated samples showed the single semicircle feature, which is similar to that observed in the case of unirradiated samples. The grain boundary resistance reduced gradually as the gamma dosage increased. The achieved outcomes proved that the structural defects induced by gamma exposure had a superficial influence on the structural, morphological, optical, PL, and impedance properties of CsPbBr3 thin films. The impact of gamma dose on the properties makes CsPbBr3 thin films significantly useful as sensing materials.

Key comparison BIPM.RI(I)-K4 of the absorbed dose to water standards of the NRC, Canada and the BIPM in 60Co gamma radiation

Main textA new key comparison of the standards for absorbed dose to water of the National Research Council of Canada (NRC), Canada and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in October 2020. The comparison result, based on the calibration coefficients for three transfer standards and evaluated as a ratio of the NRC and the BIPM standards for absorbed dose to water, is 0.9995 with a combined standard uncertainty of 3.4 parts in 103. The result agrees within the uncertainties with the comparison carried out in 2009. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the NRC, Canada and the BIPM in 60Co gamma radiation

Main textA new key comparison of the standards for air kerma of the National Research Council of Canada (NRC), Canada and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in October 2020. The comparison result, based on the calibration coefficients for three transfer chambers and expressed as a ratio of the NRC and the BIPM standards for air kerma, is 1.0022 with a combined standard uncertainty of 2.2 parts in 103. The result agrees within the uncertainties with the indirect comparison carried out in 2009. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Effect of gamma radiation on gentiopicroside production in Gentiana kurroo Royle in vitro cultures

Gentiopicroside (GPD) is one of the vital bioactive molecules present in the rhizomes, roots and aerial parts of Gentiana kurroo Royle. In this study, callus and in vitro shoots cultures of G. kurroo were treated with different doses of gamma radiation to assess its effect on the concentration of GPD. The callus was established on MS media fortified with Indole-3-butyric acid (IBA) and Indole-3-acetic acid (IAA) and exposed to variable radiation doses (0, 10, 20, 30, 40, 50, or 60 Gy 60Co gamma rays). Similarly, in vitro shoots raised in MS media supplemented with 6-Benzylaminopurine (BAP) and IAA were irradiated at (0, 10, 20, 30, 40, 50, 60, or 70 Gy 60Co gamma rays). In vitro cell growth and GPD content were assessed during M1V1, M1V2, M1V3, and M1V4 (Mutation and Vegetative) generations. The lethal dose (LD50) for both callus and shoots were observed at 35 Gy. The results revealed that low radiation doses favored growth and showed increased GPD content in the callus cultures during M1V1 generation, but both parameters were reduced in the M1V2, M1V3 and M1V4 generations. However, shoots irradiated at low doses boosted the growth and GPD level during M1V2, M1V3 and M1V4 generations. This is the first report that used gamma radiation to show the effect of GPD elicitation in the genus Gentiana.

Feasibility study of Isfahan MNSR as a calibration thermal neutron source

In the present work, the thermal beam-tube of Isfahan Miniature Neutron Source Reactor (MNSR) with known neutron dose-equivalent rate and flux is investigated as a calibration source of thermal neutrons. It is shown that 90% of the neutrons emerging from this tube are thermal. Measuring the response of TLD-600 and TLD-700 dosimeters exposed to these neutrons reveals that the both dosimeters respond linearly to neutrons in the range of 0.1 to 38 mSv. Moreover, after subtracting the contribution of mixed gamma rays using the calibration curves obtained in a standard 60Co gamma rays field, the response of TLD-600 dosimeter still behaves linearly with dose-equivalent. Finally, it is concluded that the dose-equivalent rate and flux of thermal neutrons in Isfahan MNSR are stable with time and this reactor can reliably be used as a calibration source for thermal neutrons.

Assessment of Radiation Shielding Properties of Polymer-Lead (II) Oxide Composites

Long term exposure to very high levels of radiations from medical diagnostic centres, industries, nuclear research establishments and nuclear weapon development have resulted in health effects such as cancer and acute radiation syndrome, hence the need for proper radiation shielding. This paper investigated Epoxy-Lead (II) Oxide (PbO) composite as radiation shielding. The composites were prepared by dispersion of microsized PbO particles into polymeric materials using effective melt-mixing method and cast in a 4 cm by 6 cm rectangular aluminium Mold with a thickness of 5 mm and was allowed to set over night at room temperature. The gamma ray attenuation ability of the composites were studied using gamma ray transmission or attenuation coefficient determination for the gamma ray energy. Three gamma ray sources Ba-133, Cs-137 and Co-60 were employed. The density, linear attenuation coefficient, half value layer (HVL), relaxation length and heaviness of the samples were determined. The measured values of linear attenuation coefficient increased with increasing filler concentration in all the samples at all gamma ray energies. It was also noticed that 40 % and 50 % filler samples attenuates more relative to the other samples under study. The maximum linear attenuation attained was found at energy of 662 keV. The composites have been found to possessed medical gamma-ray attenuation characteristics among the sample materials over a certain photon energy range (0.08 MeV–1.332 MeV) and found useful as a biological radiation shielding against gamma rays.

Changes in frequency-dependent dielectric features of monolayer graphene/silicon structure due to gamma irradiation

The present work intends to discover the influences of 60Co gamma (γ) ray-irradiation on frequency-dependent dielectric features of Graphene/Silicon Schottky diode with an insulator layer. Graphene (Gr) nanosheets have been synthesized by chemical vapor deposition (CVD) to build a Gr-based p-type Si Schottky diode. The diode was irradiated at 30 kGy and 60 kGy doses. The study has been performed at 300 K in the voltage range −6 V to +6 V at dark conditions both at 400 kHz low-frequency and 900 kHz high-frequency. The experimental results showed that dielectric features of the structure are dependent on the radiation dose and applied voltage and to be a strong function of frequency.

Effect of Gamma Irradiation on Survivability, Growth Performances and Floral Characters of Jasminum officinale (Samanpichcha)

Physical mutagenesis is an effective mutational breeding method for improving various growth and floral characteristics of ornamental plants. The experiment was undertaken with an objective to investigate the effect of various dosages of gamma irradiation on survivability, growth and floral characteristics of Jasminum officinale plants raised by rooted cuttings. The 60CO Gamma irradiation source at Horticultural Crop Research and Developmental Institute, Gannoruwa was used to expose rooted plants to different dosages such as 0Gy, 17Gy, 21Gy, 25Gy, 29Gy and 33Gy. A Complete Randomized Design with four replicates having 10 plants for each replicate was practiced. The results revealed that gamma irradiation dosage from 25Gy to 33Gy significantly decreased the survivability of J. officinale plants (P&lt;0.05). LD50 of gamma radiation on J. officinale was occurred around 33Gy at maturity stage. Plant height and shoot length were significantly reduced by gamma irradiation dosages of 17Gy to 33Gy compared to the control and significant reduction of shoot number was observed at 33Gy. Gamma irradiation with 17Gy dosage, it showed a significant reduction in petal width (0.82 cm) of flowers. None of the other dosages were able to develop a change in the floral characteristics of J. officinale. The study showed that 33Gy gamma irradiated plant, it is having significant reduction of plant height, number of shoots and shoot length hence it could be domesticated as a dwarf and potted plant.

Response of the Ti and Al electron spin resonance signals in quartz to X-ray irradiation

Equivalent dose determination with electron spin resonance (ESR) involves laboratory irradiation of samples using a calibrated source. In this study, we investigated the response of the quartz ESR signals to irradiations from 50 kV or 200 kV X-ray sources by inter-comparison with 60Co gamma irradiation using seven quartz samples of different origins. For each sample, the equivalent X-ray irradiation time required to create the same concentration of defects as a known dose of 60Co gamma-ray was calculated. The effective dose rate was obtained from the given gamma dose (188 Gy) divided by the equivalent X-ray irradiation time; this is referred to as the ‘X-ray dose rate’ in this study. The X-ray dose rate estimates from different samples were relatively uniform. However, the dose rate calculated from the Al centre was on average ∼10% higher than that of the Ti centre, and more scattered among different samples especially for the low-energy X-ray source. The ratio of the dose rates, obtained from the two centres (Al/Ti) varied significantly between the samples; four sediment samples from Tajikistan, China, Chile and Greece yielded consistent dose rates from both centres for both sources, whereas the remaining three samples from Japan and Taiwan showed a dose rate up to 26% higher from the Al centre compared to the Ti centre. The cause of the higher effective dose rate for the Al centre for these three samples requires further investigations.

Gamma-blindness & neutron detection efficiency assessments with centrifugally tensioned metastable fluid detectors in low-scatter environment

A range of tests and associated analyses were performed in a state-of-art low scatter environment to demonstrate and validate the performance of the (Medium) Centrifugally Tensioned Metastable Fluid Detector (MCTMFD) for gamma blind detection of fast and epithermal neutrons for a variety of configurations, using Cf-252 and Am-Li isotope neutron sources. All measurements were performed in the Low Scatter Room (LSR) of Radiological Exposures & Metrology Laboratory at Pacific Northwest National Laboratory (PNNL). Experiments were performed to evaluate intrinsic neutron detection efficiency, ɛint n, the intrinsic gamma-neutron detection efficiency, ɛintγn, and the gamma absolute rejection ratio for neutrons (GARRn) as a function of tensioned metastable state negative pressure, Pneg, varying from 2.5 bar towards 9 bar. The specific embodiment of the MCTMFD utilized for the experiments at PNNL included a 16 cm 3 sensitive volume configured for either fast neutron detection using Decafluoropentane (DFP) as the detection medium, or fast and thermal neutron detection (using DFP with a chemical mixture composed of natural boron). Experiments were performed with Cf-252 neutron sources ranging in intensity from 1 × 104 n/s to 3.45 × 105 n/s, an Am-Li neutron source with intensity of 2.5 × 104 n/s, used in both a bare configuration and in combination with a 30 cm OD moderating sphere of D2O, with and without a 0.5 mm Cd shell, and intense Cs-137 and Co-60 gamma sources offering dose rates ranging from 27 mR/h to 53 R/h. It was found that the MCTMFDs remained gamma-blind (ɛintγn < 10−11) even under 53 R/h gamma background; the associated intrinsic fast neutron detection efficiency (ɛint n) varied from ∼0.2% for Pneg ∼2.5 bar, ∼10% for Pneg ∼5.5 bar and, ∼30% for Pneg ∼9 bar for a Cf-252 fission spectrum. In comparison, for the softer (Am-Li) spectrum, the ɛint n varied from ∼1% for Pneg ∼5.5 bar and approached the ɛint n values for Pneg states above 7 bar. The same MCTMFD when using a borated detection fluid with 20% B-10, offered a ×10–20 improvement in ɛint n for Pneg states ranging from 4.5–5 bar, for detecting epithermal neutrons from the Am-Li source (placed within a 30 cm OD, D2O moderator with and without a 0.5 mm Cd shield).

Characterization of new primary air kerma standards for dosimetry in Co-60, Cs-137 and Ir-192 gamma ray sources

Introduction. To be better suited for measurements at air kerma rates which are common for the calibration of detectors for dosimetry in brachytherapy and radiation protection, two graphite-wall, air-filled cavity ionization chambers (PS-10 and PS-50 built by PTW of Freiburg, Germany) were characterized for use as primary standards at the Physikalisch-Technische Bundesanstalt (PTB) for 60Co, 137Cs and 192Ir gamma ray sources. Methods. Applying experimental or Monte Carlo methods, corrections were determined for wall effects, stem scattering effects, point-source non-uniformity, saturation effects, and deviations from Spencer-Attix cavity theory. The geometrical cavity volume of the ionization chambers was determined by a special experimental method. Non-charge-collecting parts of the volume were calculated by finite-element simulations. In addition, mass electronic stopping powers and mass-energy absorption coefficients were reevaluated in close agreement with ICRU 90. To compare the results to an already established air kerma standard, measurements of air kerma rates were taken for gamma rays from all three sources. Results. In contrast to the standards currently in use, the newly characterized ionization chambers show significant wall effects up to 4.17% (192Ir). For the PS-10 ionization chamber, the geometric volume differs by 0.42% from the charge collecting volume. For the ^192Ir source, Spencer-Attix corrections were applied exceeding 0.30% for both ionization chambers. Applying the derived corrections factors, air kerma rates measured with the two ionization chambers at the three sources did not differ by more than 0.13%. Comparing the results to an already established air kerma standard, deviations ranged up to 0.61%. The uncertainty budget for the determination of air kerma rates resulted in a relative combined standard uncertainty of 0.35%. Conclusion. Both ionization chambers can be used as primary air kerma standards for 60Co, 137Cs and 192Ir gamma ray sources using the values of corresponding physical quantities and correction factors derived in this work.

Characterisation of a synthetic diamond detector for end-to-end dosimetry in stereotactic body radiotherapy and radiosurgery.

Background and purposeSynthetic diamond detectors offer real time measurement of dose in radiotherapy applications which require high spatial resolution. Additional considerations and corrections are required for measurements where the diamond detector is orientated at various angles to the incident beam. This study investigated diamond detectors for end-to-end testing of Stereotactic Body Radiotherapy (SBRT) and Stereotactic Radiosurgery (SRS) in the context of dosimetry audits.Material and methodsSeven individual diamond detectors were investigated and compared with respect to warm up stability, dose-rate dependence, linearity, detector shadowing, energy response, cross-calibration, angular dependence and positional sensitivity in SBRT and SRS.ResultsLarge variation in the cross calibration factors was found between the seven individual detectors. For each detector, the energy dependence in the cross calibration factor was on average <0.6% across the beam qualities investigated (Co-60 Gamma Knife, and MV beams with TPR20,10 0.684–0.733). The angular corrections for individual fields were up to 5%, and varied with field size. However, the average angular dependence for all fields in a typical SRS treatment delivery was <1%. The overall measurement uncertainty was 3.6% and 3.1% (2σ) for an SRS and SBRT treatment plan respectively.ConclusionSynthetic diamond detectors were found to be reliable and robust for end-to-end dosimetry in SBRT and SRS applications. Orientation of the detector relative to the beam axis is an important consideration, as significant corrections are required for angular dependence.