137Cs Γ-rays Research Articles

Luminescence properties of Sm-doped CaCl2, SrCl2, and BaCl2 bulk crystal scintillators

Sm-doped CaCl2, SrCl2, and BaCl2 bulk crystals were synthesized using the conventional vertical Bridgman method, and the photoluminescence, radioluminescence, and detector properties were evaluated. The Sm-doped CaCl2, SrCl2, and BaCl2 samples show a broad emission band at 750, 690, and 650 nm, respectively, which is attributable to the 5d-4f transitions of Sm2+. The pulse height spectra under 137Cs γ-rays (662 keV) show that the Sm-doped CaCl2 and SrCl2 exhibit 9300 and 33000 photons/MeV, respectively. These samples can be used for γ-ray measurements in the red to NIR region.

Fabrication and luminescence properties of (K,Rb)2CuCl3 single crystal scintillators with one-dimensional structures

(K,Rb)2CuCl3 single crystal scintillators with one-dimensional structures were successfully fabricated by the slow cooling method, and their luminescence properties were evaluated. Broad photoluminescence (PL) peaks were observed at 350–500 nm, and the highest PL quantum yields were 96.4 % for (K0.5,Rb0.5)2CuCl3 among the samples. Under X-ray irradiation, scintillation peaks attributed to the recombination of self-trapped excitons were observed within the range of 350–500 nm. Both PL and scintillation decay time constants were obtained to be 10–15 μs. The best afterglow levels at 20 ms after X-ray irradiation for 2 ms were 5 ppm for (K0.75,Rb0.25)2CuCl3. The highest scintillation light yield was 16,000 photons/MeV for (K0.75,Rb0.25)2CuCl3 under 137Cs γ-rays (662 keV) irradiation. The results indicate that (K,Rb)2CuCl3 single crystals are promising as scintillators with high LY, low afterglow, and no hygroscopicity.

The impact of dose rate on responses of human lens epithelial cells to ionizing irradiation

The knowledge on responses of human lens epithelial cells (HLECs) to ionizing radiation exposure is important to understand mechanisms of radiation cataracts that are of concern in the field of radiation protection and radiation therapy. However, biological effects in HLECs following protracted exposure have not yet fully been explored. Here, we investigated the temporal kinetics of γ-H2AX foci as a marker for DNA double-strand breaks (DSBs) and cell survival in HLECs after exposure to photon beams at various dose rates (i.e., 150 kVp X-rays at 1.82, 0.1, and 0.033 Gy/min, and 137Cs γ-rays at 0.00461 Gy/min (27.7 cGy/h) and 0.00081 Gy/min (4.9 cGy/h)), compared to those in human lung fibroblasts (WI-38). In parallel, we quantified the recovery for DSBs and cell survival using a biophysical model. The study revealed that HLECs have a lower DSB repair rate than WI-38 cells. There is no significant impact of dose rate on cell survival in both cell lines in the dose-rate range of 0.033–1.82 Gy/min. In contrast, the experimental residual γ-H2AX foci showed inverse dose rate effects (IDREs) compared to the model prediction, highlighting the importance of the IDREs in evaluating radiation effects on the ocular lens.

Design and preparation of WBX/Al composites for nuclear radiation protection

As the utilization of nuclear energy continues to expand, there is a growing focus on the development of lightweight and efficient nuclear shielding composites. In this paper, novel WBX/Al (x = 1, 2, 4) composites were designed based on shielding performance. The effects of reinforcement type, volume fraction, and material thickness on the 60Co and 137Cs γ-rays, fast and thermal neutron shielding performances were simulated. The results show that WB/Al composites offer better development potential compared to WB2/Al or WB4/Al composites. Additionally, a predictive model for the γ-ray shielding effectiveness of WB/Al composites, based on the areal density of tungsten, was proposed. The fabrication process involved mechanical ball milling and spark plasma sintering to fabricate 30 vol% WB/Al composites, with optimization of ball milling time, sintering temperature, and holding time. As a result, a novel nuclear radiation protection composite with uniform composition, a relative density of 97 %, and flexural strength of 527 MPa was acquired.

Optical properties of pure and Sn-doped β-Ga2O3 single crystals grown by optical float zone technique

High-quality single crystals of both pure and Sn:β-Ga2O3 single crystals weregrown using the optical floating zone technique and a comprehensive study of its luminescence and scintillation properties was carried out. The pure and Sn:β-Ga2O3 grown crystals were oriented along (100) by Laue diffraction pattern and its monoclinic structure was confirmed using a single crystal XRD. X-ray induced luminescence spectrum shows a maximum emission peak at 365 nm. The cut off wavelength was observed around 258 nm and the optical band gap was calculated to be 4.64 eV from UV–Vis-NIR transmission spectroscopy. The room temperature Raman spectra were recorded and the various vibration modes were investigated. Low temperature (10 to 300 K) and high temperature (325 to 675 K) TL measurements were carried out on X-ray irradiated crystals and its TL kinetic parameters such as activation energy (eV) and frequency factor (S) were calculated. Scintillation decay time profiles were measured for both pure and Sn-doped crystals under 137Cs γ-ray excitation. The calculated scintillation light output is 2300 Ph/5.5 Mev for Sn:β-Ga2O3 crystal under α-particle excitation from 241Am radiation source.

Investigation of K2Cu(Cl,Br)3 crystalline scintillators

K2Cu(Cl,Br)3 crystals were prepared by the slow cooling method and evaluated for photoluminescence (PL) and scintillation properties. PL emission and scintillation peaks due to the recombination of excitons were observed at 400 nm. The PL quantum yields were estimated to be 61.0% for K2CuCl3, 72.7% for K2Cu(Cl0.5,Br0.5)3, and 75.8% for K2CuBr3, respectively. The scintillation decay curves were approximated by a single exponential function model, and the calculated decay time constants were 14–60 μs. The afterglow levels at 20 ms passed after X-ray irradiation were obtained to be 5–1225 ppm. The light yields of K2CuCl3 and K2Cu(Cl0.5,Br0.5)3 were 7700 and 9900 photons MeV−1 when calculated from the pulse height spectra under 137Cs γ-ray (662 keV) irradiation.

Optical and scintillation characteristics of Tb-doped SrY2O4 single crystals

The optical and X-and γ-ray induced scintillation characteristics of Tb-doped SrY2O4 single crystals using the floating zone technique were evaluated. Under UV and X-rays, several lines in the range of 350 to 650 nm were observed in all the prepared crystals, which were attributed to the Tb3+ ions. In the pulse area spectra of a 137Cs γ-ray source, the full-energy absorption peak was confirmed using a 1.0% Tb-doped crystal, and the light yield was estimated to be 12,000 photons/MeV.

Photoluminescence and scintillation properties of Pr-doped (Lu, Y)2Si2O7 crystals

Pr-doped (Lu1−x , Y x )2Si2O7 (x = 0.25, 0.5, and 0.75) crystals were synthesized by the floating zone method. Emission peaks due to 5d–4f transitions of Pr3+ were observed at 300 nm under excitation of both UV light and X-rays. Scintillation decay times of 19–22 ns were obtained, and they originated from the 5d–4f transitions of Pr3+. Afterglow levels became high from 64.7 to 541 ppm as the Y-admixed concentration increased. The light yields were estimated to be 560–700 photons MeV−1 by comparing the channels of photoabsorption peaks from the pulse height spectra of 137Cs γ-rays measured using prepared crystals and commercial Gd2SiO5 reference.

Scintillation light yield of Tb-doped Lu2O3 single crystals

The photoluminescence and radioluminescence properties of Tb-doped Lu2O3 (Lu2O3:Tb) single crystals were assessed for scintillator applications. Lu2O3:Tb exhibits several sharp peaks at 490, 540, 590, and 620 nm attributed to Tb3+, and the decay curves show the typical decay time for Tb3+ in millisecond range. The decay decreases with increasing dopant concentration owing to concentration quenching. Energy distributions under 137Cs γ-rays demonstrate that the 0.1 % Tb-doped Lu2O3 exhibits the highest scintillation light yield (75,000 photons/MeV) among the samples.

Scintillation properties of In-doped NaI transparent ceramics

In-doped NaI transparent ceramic scintillators were synthesized by the spark plasma sintering method, and In-doped NaI single crystal was grown by the Bridgman–Stockbarger method. The diffuse transmittance at the emission wavelength was ∼70% for the transparent ceramics and ∼90% for the single crystal. In the scintillation spectra under X-ray irradiation, emission peaks were observed at around 320, 460, and 510 nm in both of the transparent ceramic and single crystal samples. The peaks at 460 and 510 nm are due to 3P1 →1S0 transitions of In+. The decay time constants of the transparent ceramics and the single crystal were 1.8 μs. The X-ray induced afterglow level of the 0.1% In-doped NaI transparent ceramic and the single crystal was 170 and 777 ppm, respectively. In pulse height analysis, 662 keV photoabsorption peaks were clearly observed in all the samples when irradiated with 137Cs γ-rays. The light yield of the 0.1% In-doped NaI transparent ceramic was 19,000 ph/MeV, and that of the 0.1% In-doped NaI single crystal was 12,000 ph/MeV. The transparent ceramics showed better scintillation properties than the single crystal.

Protective effect of Opuntia ficus indica cladode extract against gamma radiation-induced DNA strand breaks and base damage

Radiation therapy-related toxicity is becoming increasingly important as cancer treatment outcomes improve. It is common for radiation to damage cancer cells and normal cells by hydrolyzing H2O which leading to free radicals production. Response transcription factors and signal transduction pathways are activated, resulting in DNA damage. Natural antioxidants have attracted a lot of attention. My study aimed to assess the effectiveness of cactus cladode extract (CCE) in protecting DNA plasmids against γ-radiation. The samples were irradiated with 137Cs γ-rays at different doses in the absence or presence of CCE. Agarose gel electrophoresis analysis shows that the aqueous CCE prevents radiation-induced DNA damage. Indeed, the yields of SSB and DSBs are (78 ± 3) x10−4/Gy/plasmid and (0.75 ± 0.09) x 10−4/Gy/plasmid, respectively. However, the greatest fits for the yields for SSB and DSB forming, in the presence of CCE1 (0.5 μg), are (44 ± 2) x10−4/Gy/plasmid and (0.55 ± 0.05) x 10−4/Gy/plasmid, respectively. Despite, the yields for SSB and DSB formation in the presence of CCE2 (1 μg), are (31 ± 2) x10−4/Gy/plasmid and (0.48 ± 0.09) x 10−4/Gy/plasmid, respectively. While, the yields for SSB and DSB formation, in the presence of CCE3 (1.5 μg), are (22 ± 2) x10−4/Gy/plasmid and (0.4 ± 0.02) x 10−4/Gy/plasmid, respectively. Moreover, the CCE efficiently inhibit DNA base damage. A decrease of 70%, 83%, and 87% of the Nth-sensitive sites was found when the sample was irradiated with CCE1, CCE2, and CCE3, respectively. Moreover, we calculated a decrease of 66%, 79%, and 82% of the Fpg-sensitive sites when the sample was irradiated with CCE1, CCE2, and CCE3, respectively. In conclusion, my results indicate that the CCE is a potent radioprotector and hydroxyl radical scavenger; it efficiently inhibits DNA SSBs, DSBs and base damage. It suggests that this extract may be able to protect against genotoxicity, apoptosis, and nephrotoxicity.

Radiation-induced luminescence and photoluminescence properties of (K,Rb)2CuBr3 crystals synthesized by the slow cooling method

(K,Rb)2CuBr3 crystals were fabricated by the slow cooling method, and their photoluminescence (PL) and scintillation properties were examined. Emission bands were observed at 350–550 nm under UV and X-ray irradiation. PL quantum yields of K2CuBr3, (K0.25,Rb0.75)2CuBr3, (K0.5,Rb0.5)2CuBr3, (K0.75,Rb0.25)2CuBr3, and Rb2CuBr3 were respectively 75.8, 71.0, 82.3, 96.9, and 96.3%. The scintillation decay curves were approximated by a sum of three exponential functions, and the decay time constants due to recombination of self-trapped excitons were 58–63 μs. The afterglow levels of the K and Rb-mixed samples at 20 ms passed after X-ray irradiation decreased to 10–40 ppm, compared with those of K2CuBr3 and Rb2CuBr3. Among these samples, (K0.75, Rb0.25)2CuBr3 showed the highest light yield of 7400 ph/MeV among the samples calculated from the pulse height spectra of 137Cs γ-rays (662 keV).

Sparing and enhancing dose protraction effects for radiation damage to the aorta of wild-type mice

Purpose Our previous work indicated the greater magnitude of damage to the thoracic aorta at 6 months after starting 5 Gy irradiation in descending order of exposure to X-rays in 25 fractions > acute X-rays > acute γ-rays > X-rays in 100 fractions ≫ chronic γ-rays, in which the limitations of the study included a lack of data for fractionated γ-ray exposure. To better understand effects of dose protraction and radiation quality, the present study examined changes after exposure to γ-rays in 25 fractions, and compared its biological effectiveness with five other irradiation regimens. Materials and Methods Male C57BL/6J mice received 5 Gy of 137Cs γ-rays delivered in 25 fractions spread over six weeks. At 6 months after starting irradiation, mice were subjected to echocardiography, followed by tissue sampling. The descending thoracic aorta underwent scanning electron microscopy, immunofluorescence staining and histochemical staining. The integrative analysis of multiple aortic endpoints was conducted for inter-regimen comparisons. Results Exposure to γ-rays in 25 fractions induced vascular damage (evidenced by increases in endothelial detachment and vascular endothelial cell death, decreases in endothelial waviness, CD31, endothelial nitric oxide synthase and vascular endothelial cadherin), inflammation (evidenced by increases in tumor necrosis factor α, CD68 and F4/80) and fibrosis (evidenced by increases in transforming growth factor β1, alanine blue stain and intima-media thickness). The integrative analysis revealed biological effectiveness in descending order of exposure to X-rays in 25 fractions > acute X-rays > γ-rays in 25 fractions > acute γ-rays > X-rays in 100 fractions ≫ chronic γ-rays. Conclusions The results suggest that dose protraction effects on aortic damage depend on radiation quality, and are not a simple function of dose rate and the number of fractions.

Accelerator-driven photon reference field for replacement of 137Cs γ-ray

A transition to a mechanical source for x-ray reference field is desired to replace high-activity Co-60 and Cs-137 gamma-ray sources for enhancing nuclear security and safety management. The National Metrology Institute of Japan (NMIJ) developed a new photon reference field using an electron beam from a linac with energy less than 1 MeV. The effective energy of the photon field is comparable with Cs-137 gamma-ray. The air kerma rate in the reference field was validated by comparing a commercial cavity ionization chamber to the NMIJ standard reference field. The calibration constants were consistent within 0.8% for every relative extended uncertainty (k = 2).

Flow filtration/adsorption and simultaneous monitoring technologies of radiocesium 137Cs in river water

This study develops a method that combines a radiation-grafting fibrous Cs-adsorbent filter of ammonium molybdophosphate (AMP) and a Ce:Gd3Al2Ga3O12 scintillator-based γ-ray detector for in situ measurements of the activity concentrations of 137Cs in a continuous water flow. To ensure adequate performance, the study locations were set along an upper tributary stream of the Ukedo River and a nearby spring-fed stream, approximately 30 km northwest of the Fukushima Daiichi Nuclear Power Plant. In the tributary stream, the activity concentrations of 137Cs slowly decreased from 19 to 1.7 mBq/L between 2018 and 2020 until reaching equilibrium with a few millibecquerels in 10 years after the accident. This equilibrium value is significantly below the admissible radiocesium activity (10 Bq/L) for drinking water. The spring-fed stream rarely included 137Cs. The monitoring results support previous views about the environmental fate of 137Cs in a forest ecosystem at the Abukuma granitic catchments. The major advantage of this method is that utilizing fibrous Cs adsorbents with AMP-loaded graft chains enables the effective accumulation of 137Cs through a large amount of stream water. Therefore, 137Cs γ-rays can be detected simultaneously, and combining these strategies provide a unique monitoring platform for on-site and real-time detection of 137Cs at the trace level.

Development of Tl-doped KI single crystal scintillators

Tl-doped (0.1, 0.3, 1, and 3%) KI single crystals were synthesized, and photoluminescence and scintillation characteristics of KI:Tl were evaluated. An emission peak at ∼420 nm was observed under ∼300 nm excitation in all the samples. All the synthesized samples exhibited a peak at 420–440 nm and a tail emission at ∼350 nm under X-ray irradiation. These origins would be 3P1→1S0 transitions of Tl+ (420–440 nm) and the off-center configuration of the self-trapped excitons (∼350 nm), respectively. According to pulse height spectra under γ-ray irradiation, scintillation light yield (LY) and the energy response were investigated. The 0.3% KI:Tl showed the highest LY of 7,300 photons/MeV among the prepared samples and ∼11% energy resolution under 137Cs γ-ray (662 keV) irradiation. The energy response of the 0.3% KI:Tl illustrated a good linearity against γ-ray energies from 22 to 1,408 keV.

Sensitivity of Gaussian energy broadening function of MCNP pulse height spectra on CLYC7 scintillation detector

The Cs2LiYCl6:Ce crystal (CLYC) is an inorganic scintillator which has been developed for the γ-ray and neutron measurement with the high detection efficiency, high resolution, and no need unfolding technique. To enhance the measurement of the fast neutron, the CLYC with 7Li-enrichment (CLYC7) scintillator is developed. In this work, the response of the CLYC7 detector to γ-ray is obtained using 137Cs γ-ray calibration source and calculated using Monte Carlo N-Particle transport code (MCNP). A comparison of measured and calculated γ-rays spectra is complicated by the fact that physical radiation detectors have finite energy resolution. In this study, we treated detector energy resolution effect by Gaussian energy broadening (GEB) in MCNP pulse height spectra calculation. We observe the parameters in the GEB function which provides simulation spectrum matches the experiment spectrum, especially on the photopeak region. The detail sensitivity of GEB function on CLYC7 scintillation detector is presented in this work.

The Antiapoptotic Effect of Danggui Buxue Tang and Its Main Components on Hematopoietic Cells in Mice with Bone Marrow Suppression

To explore the hematopoiesis protection effect of Danggui Buxue Tang (DBT) and its main components Angelica polysaccharide (APS) and Astragalus polysaccharide (ASPS) on myelosuppression mice, and the mechanism of anti-apoptosis of Meg-01 cells. Mice were radiated with 4 Gy of 137Csγ ray to establish the model of radiation-induced myelosuppression. DBT, APS or ASPS (10 mg/kg) were injected into irradiated mice. Peripheral blood cell counts were performed on mice before radiation (day 0) and day 7, 14 and 21 after radiation. On the 21st day, poor plasma platelets were collected from mice to detect TPO concentration and then the mice were sacrificed. The femoral bone marrow cells were cultured for colony cell forming units (CFU). Meg-01 cells were cultured without FBS for 24 h to induce apoptosis, and then treated with DBT/APS/ASPS for 72 h. Flow cytometry (FCM) was used to detect early apoptosis (Annexin V), mitochondrial membrane potential (JC-1) and the expression of Caspase-3 to analyze the effect of DBT/APS/ASPS on cell apoptosis. DBT can stimulate the recovery of white blood cells (WBC), red blood cells (RBC) and platelets (PLT) of myelosuppression mice, especially for WBC and PLT (P<0.01, P<0.05). Compared with the control group, the number of BFU-E, CFU-MK and CFU-GM increased after adding DBT (BFU-E & CFU-GM: P<0.05； CFU-MK: P<0.01). The effect of DBT on blood TPO concentration in mice was not obvious (P=0.89). RBC, WBC and PLT were increased in APS group compared with control group (P<0.05). WBC increased after the treatment of ASPS (P<0.05). APS stimulated the formation of CFU-F, CFU-MK and CFU-GM (P<0.05). Only CFU-GM increased in ASPS group(P<0.05). Besides, DBT decreased the apoptosis of Meg-01 cells (P<0.05). The early apoptosis rate and total death rate in APS (100 μg/ml) group were lower than that of control group (P<0.01, P<0.05). The early apoptosis rate of ASPS (100 μg/ml) group was lower than that of control group (P<0.05). JC-1 and Caspase-3 showed that APS (100 μg/ml) significantly reduced apoptosis rate (P<0.01, P<0.05). DBT has protective effect on hematopoietic system, especially WBC and PLT, and has anti-apoptotic effect on Meg-01. It was found that the above effects of DBT were mainly caused by APS, and its anti-apoptosis mechanism was carried out mainly through JC-1 and Caspase-3 pathways.

The Hematopoietic Protective Effect of PDGF-BB on Radiation-Induced Myelosuppression Model Mice

To investigate the hematopoietic protective effect of platelet-derived growth factor (PDGF)-BB on radiation-induced myelosuppression model mice and effect of anti-apoptosis of megakaryocyte line Meg-01 cells, and its possible mechanism. Mice were radiated with 4 Gy of 137Csγ ray to establish the model of myelosuppression. Mice were weighed and peripheral blood cell were counted before radiation (day 0) and day 7, 14 and 21 after radiation. On the 21 st day, the mice were killed. The sternal tissues of the mice were taken for morphological observation, and the femoral bone marrow cells were cultured for the assay of colony cell forming units (CFU). Meg-01 cells were cultured without FBS for 24 h to induce apoptosis, and then treated with PDGF-BB for 48 h. The effects of PDGF-BB on the proliferation were investigated by cell counting. Flow cytometry was used to detect early apoptosis (Annexin V), mitochondrial membrane potential (JC-1) and the expression of caspase-3. Peripheral blood cell counts of mice showed that PDGF-BB stimulated the recovery of white blood cells, red blood cells and platelets after radiation (P<0.05), especially for white blood cells. Morphological examination showed bone marrow hyperplasia in PDGF-BB group, the numbers of megakaryocytes and their progenitor cells were higher than those in the control group. PDGF-BB significantly stimulated the formation of CFU-MK, CFU-GM, BFU-E and CFU-F. PDGF-BB showed a strong proliferation effect in the concentration range of 5-50 ng/ml (P<0.001). PDGF-BB (50 ng/ml) significantly reduced the positive expression of Annexin V (P<0.01). The mitochondrial membrane potential in the control group was decreased when compared with PDGF-BB group, which indicated that the number of apoptotic cells was increased (P<0.01). Besides, the expression of caspase-3 in PDGF-BB group was significantly lower than that in control group (P<0.05). PDGF-BB has a protective effect on the hematopoietic system of myelosuppression model mice, especially megakaryocytes and their progenitor cells. PDGF-BB has pro-proliferative and anti-apoptotic effects on Meg-01 cells, and the mechanism may be mediated through JC-1 and caspase-3 pathway.

Cryogenic Scintillation Properties of Lead-Free Cs3Cu2I5 Single Crystals.

Perovskite scintillators have become increasingly popular in recent years because of their simple production and high sensitivity to X-ray. Due to large Stokes shifts, high light yield, eco-friendly fabrication, and good stability, the lead-free Cu-based perovskites have gained much attention. In this paper, we prepared the Cs3Cu2I5 single crystals (SCs) by the solution-processed method. At room temperature, we measured the emission band at 440 nm with an average decay time of 595 ns under X-ray excitation. Under 137Cs γ-ray excitation, we determined that the light yield of Cs3Cu2I5 SCs was 23 000 photons/MeV. Notably, under alpha particle excitation by 241Am, the light yield of Cs3Cu2I5 SCs is approximately 3.2 times higher than that of the commercial scintillator LYSO(Ce). In addition, we systematically investigated the cryogenic scintillation properties of Cs3Cu2I5 SCs at the temperature range of 60-300 K. With decreasing temperature, the intensity of the emission band at 440 nm significantly increases, and an additional emission band at 336 nm emerges below 100 K. Meanwhile, the temperature-dependent decay times were determined. The fast and slow decay time of Cs3Cu2I5 SCs are estimated to be 221 and 1193 ns, respectively, at 60 K. Our findings highlight the great potential for Cs3Cu2I5 SCs to be a cryogenic scintillator.