Liquid Scintillation Research Articles

Improved measurement of the light attenuation length of a high-quality linear alkylbenzene for the JUNO experiment

The Jiangmen Underground Neutrino Observatory (JUNO) experiment is the next-generation neutrino experiment that aims at exploring the neutrino mass hierarchy problem. Located 700m underground in Jiangmen, China, JUNO’s central detector is an acrylic sphere filled with 20kt of liquid scintillator with linear alkylbenzene (LAB) as solvent. To achieve the unprecedented energy resolution of σE/E⩽3%, the LAB used in JUNO is required for excellent transparency at the wavelength around 430nm. In cooperation with Jinling Petrochemical (Nanjing), the newly developed LAB shows an improved attenuation length. The resulting transparency of the LAB requires higher sensitivity in measurement. We have, therefore, upgraded the apparatus and the analysis method for higher precision. In this article, we present the upgraded apparatus and the analysis on improving the measurement error. Among the many new samples, the type NJ66 yields an attenuation length of approximately 30m. The analysis has applied statistical methods with Monte Carlo simulations. A new model is proposed to account for the deviations between data and the Beer–Lambert model. The long attenuation length of LAB observed in this study suggests feasibility to reach the goal on energy resolution required by JUNO.

A feasibility study on distinguishing fluor concentrations in liquid scintillators from scintillation events observed by photomultiplier tubes using convolutional neural networks

A feasibility study on distinguishing fluor concentrations in liquid scintillators from scintillation events observed by photomultiplier tubes using convolutional neural networks

Solidification of radioactive spent liquid scintillator wastes: Effect of additives on the leaching of radionuclides

Along with the widespread application of liquid scintillation counting technology in terms of detecting low-energy β nuclides, the liquid scintillator wastes generated during the process has become a kind of radioactive organic waste liquids which was widely concerned and urgently needed for treatment. In this study, sulfoaluminate cement (SAC) was used to solidify the liquid scintillator wastes. Zeolite and nano-SiO2 were introduced as additives, and the effect of two additives on the leaching rate of Sr and Cs in cement solidified forms was studied. The increase in zeolite content from 0 to 2 wt% led to a decrease in the leaching rate of Cs, while further increase in zeolite content lead to an increase in the leaching rate of Cs. The lowest leaching rate of Sr was obtained in the formula of 5 wt% zeolite. The sample with 2% nano-SiO2 added led to the highest leaching rate of Sr and Cs, and reducing or increasing nano-SiO2 resulted in a decrease in leaching rate. SAC was suitable for cementation of liquid scintillator wastes, and the 42-day leaching rate of Sr and Cs in samples without or with zeolite and nano-SiO2 had met the requirements in GB 14569.1-2011.

Standardization of rapid screening technique based on liquid scintillation counting for estimation of gross α/β activities in urine

Standardization of rapid screening technique based on liquid scintillation counting for estimation of gross α/β activities in urine

The study on distribution coefficient of polonium between tri-octylphosphine oxide (TOPO) and tri-butylphosphate (TBP) in toluene and cyclohexane and selected inorganic acids

In this work the distribution coefficients (D) of polonium between 0.1 mol dm−3 TOPO/toluene; TOPO/cyclohexane; TBP/toluene and TBP/cyclohexane and aqueous solutions of inorganic acids (HCl, HNO3, H2SO4 and H3PO4) were determinated. The molarities of inorganic acids were between 0.5 and 12.0 mol dm−3. The activity of extracted Po-209 was measured by means of liquid scintillation counting. The best result was obtained for TOPO/toluene and 2 mol dm−3 H2SO4 system (D = 62 ± 9). The most stable conditions of extraction were found for TOPO/toluene-HCl system.

LSC screening of coloured water samples for simultaneous 137Cs and 90Sr/90Y measurements during nuclear emergencies

Simultaneous screening of 137Cs and 90Sr/90Y levels in coloured water samples by Liquid Scintillation Counter Quantulus 1220 via Cherenkov counting has been investigated. Ionic liquid 1-butyl-3-methylimidazolium salicylate with wavelength-shifting properties has been added to the counting vials, which significantly improved detection efficiency. The results of 137Cs activities obtained via LSC method have been compared with conventional gamma-spectrometric measurements. The performance and limitations of the method have been demonstrated on coloured samples spiked with known 137Cs and 90Sr/90Y activities. In the case of a nuclear accident, this method can be used without sample pre-treatment so that results are obtained within 2 h. The method provides results with up to 80% relative deviation from true 137Cs and 90Sr/90Y activities in the case of highly quenched samples. Its application is limited to the prompt screening of a larger number of samples when it is necessary to efficiently detect radioactive contamination of water.

Measurement of energy and directional distribution of neutron ambient dose equivalent for the [formula omitted]Li(p,n)[formula omitted]Be reaction

Double differential neutron fluence distributions were measured in the 7Li(p,n)7Be reaction for proton beam energies 7, 9 and 12 MeV. Seven liquid scintillator based detectors were employed to measure neutron fluence distributions using the Time of Flight technique. Neutron ambient dose equivalents were determined from the measured fluence distribution using ICRP (International Commission on Radiological Protection) recommended fluence to dose equivalent conversion coefficients. Neutron dose equivalents were also measured using a conventional BF3 detector based REM counter. Ambient dose equivalent measured by the REM counter is found to be in agreement with that determined from the neutron fluence spectra within their uncertainties. Angular distributions of the ambient dose equivalents were also determined from the measured fluence distributions at different angles.

Mass Balance and Metabolic Pathways of Eliapixant, a P2X3 Receptor Antagonist, in Healthy Male Volunteers.

Overactive adenosine triphosphate signaling via P2X3 homotrimeric receptors is implicated in multiple conditions. To fully understand the metabolism and elimination pathways of eliapixant, a study was conducted to assess the pharmacokinetics, mass balance, and routes of excretion of a single oral dose of the selective P2X3 receptor antagonist eliapixant, in addition to an invitro characterization. In this single-center open-label non-randomized non-placebo-controlled phase I study, healthy male subjects (n=6) received a single dose of 50mg eliapixant blended with 3.7MBq [14C]eliapixant as a PEG 400-based oral solution. Total radioactivity and metabolites excreted in urine and feces, and pharmacokinetics of total radioactivity, eliapixant, and metabolites in plasma were assessed via liquid scintillation counting and high-performance liquid chromatography-based methods coupled to radiometric and mass spectrometric detection. Metabolite profiles of eliapixant in human invitro systems and metabolizing enzymes were also investigated. After administration as an oral solution, eliapixant was rapidly absorbed, reaching maximum plasma concentrations within 2h. Eliapixant was eliminated from plasma with a mean terminal half-life of 48.3h. Unchanged eliapixant was the predominant component in plasma (72.6% of total radioactivity area under the curve). The remaining percentage of drug-related components in plasma probably represented the sum of many metabolites, detected in trace amounts. Mean recovery of total radioactivity was 97.9% of the administered dose (94.3-99.4%) within 14 days, with 86.3% (84.8-88.1%) excreted via feces and 11.6% (9.5-13.1%) via urine. Excretion of parent drug was minimal in feces (0.7% of dose) and urine (≈0.5%). In feces, metabolites formed by oxidation represented > 90% of excreted total radioactivity. The metabolites detected in the invitro experiments were similar to those identified invivo. Complete recovery of administered eliapixant-related radioactivity was observed in healthy male subjects with predominant excretion via feces. Eliapixant was almost exclusively cleared by oxidative biotransformation (>90% of dose), with major involvement of cytochrome P450 3A4. Excretion of parent drug was of minor importance (~1% of dose). ClinicalTrials.gov: NCT04487431 (registered 27 July 2020)/EudraCT number: 2020-000519-54 (registered 3 February 2020), NCT02817100 (registered 26 June 2016), NCT03310645 (registered 16 October 2017).

Development of novel positron lifetime measurement system for potential liquid material inspection

β+-γ coincidence method and anti-coincidence method have great potential in positron annihilation lifetime (PAL) measurements of liquid material. Based on anti-coincidence method with the advantage of better picking out positron annihilation events in the sample, a novel PAL spectrometer, which can isolate the sample from the positron source and is suitable for liquid material inspection, is developed. The influences of the measuring geometry and the signal processing on the anti-coincidence effect are systematically studied. By comparing the PAL spectra of well annealed pure iron acquired by the new system with that acquired by the conventional system, the performance of system is evaluated. The analysis results of PAL spectra at different distances from the sample to the source and precise measurement of PAL in liquid water show that reliable values are obtained for liquid material inspection at an adjustable distance of less than 1.0 mm. This system is expected to be applied to liquid scintillators, oils or other special materials, which could easily contaminate the positron source.

Tritium contents in drinking and surface seawaters before the nuclear power plant planned in Sinop (Türkiye) and their radiological risks on human population.

This study aims to determine the background levels of tritium radioisotope in drinking and seawater samples of Sinop province before the nuclear power plant was established in Sinop. In this context, a total of 174 water samples were collected, these are as follows: nine drinking water samples from the Sinop center and districts and 165 seawater samples from the seacoast from Samsun to Kastamonu. Tritium concentrations in the collected water samples were measured by the liquid scintillation counter. The minimum detectable activity for the method used was found to be 1.48 Bq/L. The tritium concentrations of the seawater and drinking water samples were found in the range of <MDA (minimum detectable activity)-6.29 Bq/L and 2.45-3.17 Bq/L, respectively. In addition, the annual effective dose rates of the people consuming these drinking waters due to the tritium radioisotope were calculated separately for infants, children and adults and found to be 12.12, 16.96 and 35.38 nSv, respectively.

Assessment of Radioecologically Relevant Radionuclides 14C, 99Tc, and 129I in Vitrified High-Level Nuclear Wastes from Spent Fuel Reprocessing

A method is proposed for quantifying the specific activities of radioecologically significant radionuclides, including 14C, 99Tc, and 129I, in vitrified high-level wastes. The conditions for the separation and purification of these radionuclides from potential interfering components are optimized and the yield coefficients and purification factors are determined. The quantification of 14C entails a three-fold distillation in CO2 followed by the measurement of the 14C counting rate in the purified solution by liquid scintillation spectrometry. 129I was determined by dissolving a sample in HNO3, five-fold extraction, and the subsequent measurement of the 129I counting rate in the purified solution using liquid scintillation spectrometry. The determination of 99Тс included dissolving a sample in the presence of ClO–, double extraction-chromatographic separation of 99Тс with an adsorbent impregnated with methyltrioctylammonium nitrate, followed by the determination of its activity by inductively coupled plasma–mass spectrometry. We have applied this approach to a simulator of vitrified high-level waste, labeled with radionuclides, and achieved satisfactory results. This approach will be instrumental in the analysis of the accumulated vitrified high-level wastes at the “Mayak” Production Association (Mayak PA). The results will be important for modeling the engineering safety barriers of a deep disposal site for radioactive wastes.

Feasibility study of concentration classification based on statistical learning using image data of different concentrations of fluorescent solutes in a liquid scintillator

Feasibility study of concentration classification based on statistical learning using image data of different concentrations of fluorescent solutes in a liquid scintillator

Characterization of the scintillation response of water-based liquid scintillator to alpha particles, and implications for particle identification

Next-generation large-scale neutrino detectors, from Eos, at the 1 t scale, to Theia, at the 10 s-of-kt scale, will utilize differences in both the scintillation and Cherenkov light emission for different particle species to perform background rejection. This manuscript presents measurements of the scintillation light yield and emission time profile of water-based liquid scintillator samples in response to α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha $$\\end{document} radiation. These measurements are used as input to simulation models used to make predictions for future detectors. In particular, we present the timing-based particle identification achievable in generic water-based scintillator detectors at the 4 t, 1 kt, and 100 kt scales. We find that α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha $$\\end{document}/β\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta $$\\end{document} discrimination improves with increasing scintillation concentration and we identify better than 80% α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha $$\\end{document} rejection for 90% β\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta $$\\end{document} acceptance in 10% water-based liquid scintillator, at the 4 t scale.

Investigating the Potential of Perovskite Nanocrystal-Doped Liquid Scintillator: A Feasibility Study

Liquid scintillators are extensively employed as targets in neutrino experiments and in medical radiography. Perovskite nanocrystals are recognized for their tunable emission spectra and high photoluminescence quantum yields. In this study, we investigated the feasibility of using perovskites as an alternative to fluor, a substance that shifts the wavelengths. The liquid scintillator candidates were synthesized by doping perovskite nanocrystals with emission wavelengths of 450, 480, and 510 nm into fluor PPO with varying nanocrystal concentrations in a toluene solvent. The several properties of the perovskite nanocrystal-doped liquid scintillator were measured and compared with those of a secondary wavelength shifter, bis-MSB. The emission spectra of the perovskite nanocrystal-doped liquid scintillator exhibited a distinct monochromatic wavelength, indicating energy transfer from PPO to the perovskite nanocrystals. Using a 60Co radioactive source setup with two photomultiplier tubes (PMTs), the light yields, pulse shape, and wavelength shifts of the scintillation events were measured. The light yields were evaluated based on the observed Compton edges from γ-rays, and compared across the synthesized samples. A decrease (or increase) in area-normalized PMT pulse height was observed at higher perovskite nanocrystal (or PPO) concentrations. The results demonstrated the sufficient potential of perovskite nanocrystals as an alternative to traditional wavelength shifters in a liquid scintillator.

DETERMINATION OF GROSS ALPHA/BETA RADIOACTIVITY OF WATER SAMPLES AROUND MINING SITES, DANGE-SHUNI LGA, SOKOTO STATE

Mining activities in the Iullumeden (Sokoto) basin is often heard of due to its prominence in artisanal mode of ransacking the Earth in search of minerals and metal of high economic values. The unabated demand in the growing post-industrial era have decimated any health impact that could be borne by the inhabitants of the mining communities. Dange-Shuni is an enclave of this basin that was covered in a bid to determine the gross alpha and beta radioactivity in domestic water in and around mining points. Water samples were collected and analyzed via Hidex 300 SL system of Liquid Scintillation Counting from a systematic sampling of fifteen mining points. The results indicate that both the gross alpha and beta radioactivity concentrations were in elevation with about 80% and 85% above the global limits of 0.5 and 1.0 . The results are good reasons to work hard in order to bring dose of radioactivity exposure to the inhabitants to as low as reasonably achievable (ALARA) being a mandate of WHO.

Application of portable liquid scintillation counter for on-field measurement of tritium in aqueous samples during radiation emergency

Screening of aqueous samples for 3H contamination is required to decide suitability of water intended for human consumption during radiation emergency. BARC, Trombay has recently procured Portable Triathler liquid scintillation counter as a screening tool for on-site response to radiation emergency. For this purpose, parameters like, different available scintillators, scintillator to sample ratio and influence of different capacity scintillation vials were optimized for 3H concentration measurement. The study indicated that for 7 mL vials, the optimized scintillator to sample ratio was 4:1 for Optiphase Hisafe II, Ultima Gold Ultra Low Level Tritium, Aqualight AB and Dioxane based scintillators whereas for Ultima Gold AB and Optiphase Hisafe III scintillators it was 3:1. In case of 20 mL vials, the ratio was optimized to 8:1 for all the above mentioned six scintillators. Additionally, the effect of applying counting efficiency using calibration curves generated using distilled water and that obtained using optimized scintillator to sample ratio in various spiked water samples was also studied. Results in 3H concentration (2000–5700 Bq/mL) indicate about ±10% deviation using both the methods for commercially available scintillators. However, in case of Dioxane based scintillator, the deviation was higher (20%). For analysis of 3H concentration ∼200 Bq/mL using commercially available scintillators results in higher deviation of about 21% due to unreliable quench indicating parameter for count rate less than 4000. The study indicated that calibration curves constructed using optimized parameters are universally applicable for determination of 3H concentration in wide variety of water samples.

Estimation of gross α-β and tritium activities in groundwater samples using LSC-TDCR technique in and around the geothermal region of Eastern India.

The present study is an attempt to assess the radiogenic quality of groundwater on the basis of gross α, gross β and tritium (3H or H-3) activities in the Bakreswar-Tantloi geothermal region of Chotanagpur Plateau, West Bengal and Jharkhand, India. The aforesaid parameters in groundwater samples were measured using liquid scintillation counting triple to double coincidence ratio (LSC-TDCR) technique. Groundwater samples collected from Bakreswar-Tantloi geothermal region show gross α activities from below the minimum detectable activity (BMDA) to 0.5 ± 0.05Bq/L, gross β activities from BMDA to 0.2 ± 0.01Bq/L and H-3 activities from BMDA to 63.42Bq/L. The average gross α, gross β and H-3 activities are also within the permissible limits prescribed by the World Health Organization (WHO). Though the annual effective doses in some samples were higher than the reference dose level of 0.1mSv, the overall result suggests that the groundwater in the Bakreswar-Tantloi geothermal region is radiologically safe considering the radionuclides covered in this study.

Evaluation of long-term robustness of the International System of Reference (SIR) used in radionuclide metrology based on the meta-analysis of its machine-readable database

In support of the CIPM MRA, the reference system in radionuclide metrology (SIR) is a unique experimental facility that has been able to provide continuous key comparison results for 72 radionuclides for 46 years. These measurement data are now available in a machine-readable format, which allows statistical analysis of these measurement results to be performed efficiently. Such a meta-analysis was conducted to verify whether or not the accumulated data confirmed the bold assumption made in the 1970s of the long-term robustness of the system over decades of operation. It was notably assumed that variation in the properties of the standard solution to be measured or the choice of the 226Ra reference source would have no impact on the measurement. For the majority of radionuclides measured by the SIR, the non-parametric significance tests of the null hypothesis carried out in this study gave no evidence, at the 95% confidence level, that the above statement should be reconsidered. However, this meta-analysis revealed a significant impact of solution density in the case of 109Cd, corroborating previous observations made in the case of 241Am where the robustness of an ionization chamber with respect to the density variation of the solution does not appear to be perfect. The extension of the SIR by a liquid scintillation system is under development. It will improve the robustness of international comparison results for those borderline cases where radionuclides emit only low-energy x-rays or gamma rays (<100 keV).

ENVIRONMENTAL TRITIUM AND ITS MEASUREMENT CHALLENGES USING LIQUID SCINTILLATION COUNTING

Tritium, the radioactive isotope of hydrogen, is one of the most versatile radionuclides due to its role as a tracer of hydrogen and carbon structures. The liquid scintillation counting method is the preferred tritium measurement method especially in the case of numerous samples as radioactivity monitoring programs. The changes that appeared in the liquid scintillation spectrometers market and in the liquid scintillation cocktail formula demand adaptation of the laboratory routine procedure. Tritium level in the environmental water samples of 2022 is presented in the paper. The low level around 2 Bq/L imposes the necessity of tritium enrichment. Each of the above problems is extensively presented in this work together with some conclusions.

Simultaneous determination of 226Ra and 228Ra in food samples using liquid scintillation counting

The 228Ra and 226Ra isotopes of radium are significant contaminants in food, raising public concern because of their radiotoxicity. Several methods are available for determining 228Ra and 226Ra. However, the application of these procedures is not focused on food but only on water and environmental matrices. In this study, a cost-effective method for the simultaneous determination of 226Ra and 228Ra radioactivity in food samples using liquid scintillation counting was developed. The overall efficiencies of 226Ra and 228Ra in the food samples are 69.4–78.4% and 30.1–35.8%, respectively. The minimum detectable activities of 226Ra and 228Ra are 11.3 mBq/g and 33.4 mBq/g, respectively, in our food sample, obtained using a 1.0 g ash sample and 60 min of counting time. The method was validated using IAEA-certified reference materials and compared with data obtained using gamma spectrometry in tea, kelp, and oyster samples.