To calibrate radon progeny instruments and check the effectiveness of radon compensation for artificial radioactive aerosol instruments, a novel radon progeny generator was developed and its ...performance was tested in this study. The experimental results showed that equilibrium equivalent concentration could be controlled in the range of 1 × 10
2
–1 × 10
4
Bq·m
−3
, the equilibrium factor could be controlled in the range of 0.14–0.48, and the unattached fraction of the radon progeny could be controlled in the range of 0.02–0.5. All of these characteristic parameters could be controlled stably and efficiently within 7 h.
Underground low-background laboratories have a very large demand for radon reduction in their working environments. Therefore, in this paper, we have constructed a system for low-temperature ...activated carbon adsorption of radon by using air cooler and measured the dynamic adsorption coefficients of activated carbon on radon at room temperature and at a low temperature below − 50 °C. The experimental results show that the activated carbon dynamic adsorption coefficient reaches 688.79 L/g at a temperature of − 63.35 °C and a pressure of 3.5 atmospheres, which is more than 70 times higher than that at room temperature. During the experiments, problems of effective regulation were identified that need to be further addressed.
Crystalline solids of zeolitic imidazolate framework (ZIF)-69 with a suitable pore window size matching with atomic diameter of xenon is utilized for this task, showing notable performance for Xe/Kr ...capture and separation as well as decent hydrolytic and irradiation stabilities. The results illustrate that the saturated uptake amount of Xe by ZIF-69 is 2.46 mmol/g at 298 K, while Kr uptake is only 0.55 mmol/g. Importantly, the separation ratio of Xe/Kr is 8.35, one of the highest values among all solid sorbent material reported up to now. These findings suggest that ZIF-69 is a potential candidate for the application of xenon capture and purification form a gas mixture containing Kr.
Half of the natural radiation dose to the human body comes from indoor radon and its progeny, inhaling of which plays a key role in the development of lung cancer. Given the relationship between the ...radon exhalation rate (RnER) and the indoor radon concentration, accurate determination and control of the former directly affect the control and protection of the latter. In this study, a method was developed to estimate the actual RnER of building walls through building material samples. The surface RnER of the wall of any thickness that was constructed of any building material could be calculated by its intrinsic RnER value and radon diffusion length, which could be obtained by measuring the RnER of the pre-treated building material sample models through the activated carbon box-γ spectroscopic method. The experimental results indicated that the deviation between the calculated wall surface RnER of the building and the measured wall surface RnER of the building was <5.1%. Therefore, the intrinsic RnER of building materials could be regarded as an evaluation index for the RnER of buildings.
Soil is the primary source of radon in the atmosphere, and soil radon exhalation rate (E) is a key indicator to evaluate the radon hazard in soil. Radon can also be used as a tracer to analyze ...atmospheric processes and monitor greenhouse gas emissions. Therefore, improving the accuracy of measuring E is significant for radon protection and radon pollution management as well as public health. In this study, three different sampling methods were compared to determine the most suitable sampling method for E measurement under different conditions. The results indicated that the closed-loop gas-flow method can be used to measure E and required correction for leakage and counterdiffusion; E was found to vary from 13.25 ± 1.44 to 30.46 ± 2.19 mBq·m−2 s−1. For the open-loop gas-flow method, a low sampling flow rate was selected, and the sampling flow rate derived from this experiment was less than 0.2 l min−1; E varied from 36.11 ± 0.99 to 52.67 ± 1.68 mBq·m−2 s−1. For the activated-carbon adsorption method, the counterdiffusion effect had a negligible influence on the measurement results, and the measurement error due to the uneven distribution of radon in the carbon layer could be eliminated by changing the waiting time for the measurement; the measurement showed E of about 23 mBq·m−2 s−1. Moreover, the influence of water absorption of the activated carbon on the measurement results should be considered, and the water absorption rate should be less than 9%. The obtained values will serve as a reference for the rapid and accurate measurement of E.
•The main objective of this work is to compare the effects of sampling methods on the measurement of soil radon exhalation rates.•The activated-carbon adsorption method is hardly affected by back diffusion, and the measurement error resulting from the inhomogeneous distribution of radon in the carbon layer can be eliminated by changing the time of waiting for measurement.•Soil radon exhalation rates are measured using the closed-loop gas-flow method, which requires corrections for leakage and counter-diffusion.•A suitable sampling flow rate should be selected for the open-loop gas-flow method.•The results of the study should contribute to improving the accuracy of existing soil radon exhalation rate measurements.
The high-precision measurement of Rn-220 is essential for assessing and preventing thoron radiological hazards. Prior research has revealed that employing a scintillation cell without a clapboard ...improves the detection efficiency for both Rn-222 and Rn-220 by reducing air pressure, and the Rn-220 calibration factor is established at an atmospheric pressure of 0.4. However, the decrease in air pressure leads to a corresponding reduction in Rn-220 concentrations within the scintillation cell, resulting in lower counts and larger statistical fluctuations. For the purpose of addressing this issue, a ZnS(Ag)-coated clapboard was added to the low-pressure scintillation cell for measuring Rn-222 and Rn-220. Several experiments were conducted in conjunction with Monte Carlo simulations. The results of these simulations, along with experiments using the standard radon chamber, provide valuable references for establishing the Rn-220 calibration factor. The experimental findings demonstrate that saturated detection efficiency of Rn-222 and Rn-220 can be maintained at below 0.7 atmospheric pressure. Therefore, the Rn-220 calibration factor, determined with the detection efficiency of 0.73 ± 0.04 at an atmospheric pressure of 0.7, was determined to be 31.98 ± 1.83 Bq·m-3·min-1 (k = 1).
Calibration strategy of the JUNO experiment An, Fengpeng; Andronico, Giuseppe; Bernieri, Enrico ...
The journal of high energy physics,
03/2021, Volume:
2021, Issue:
3
Journal Article
Peer reviewed
Open access
A
bstract
We present the calibration strategy for the 20 kton liquid scintillator central detector of the Jiangmen Underground Neutrino Observatory (JUNO). By utilizing a comprehensive ...multiple-source and multiple-positional calibration program, in combination with a novel dual calorimetry technique exploiting two independent photosensors and readout systems, we demonstrate that the JUNO central detector can achieve a better than 1% energy linearity and a 3% effective energy resolution, required by the neutrino mass ordering determination.
Activated charcoal was widely used in radon researches and mitigation applications because of good adsorption ability. In the paper, a simple model that can predict radon removal efficiency (η) for ...radon mitigation applications using flow-through activated charcoal system was developed based on the previous works. Experiments were conducted with a flow-through activated charcoal system to validate the model and study the influence of factors on η. The experimental results of η are consistent with the theory to within 4% at the flow rates of 1–3 L/min, but range from 2% to 14% at the flow rates of 4–5 L/min. The equilibrium time of radon linearly decreases with rising flow rate, and η decreases with rising flow rate. With moisture competing with radon for adsorption sites on the activated charcoal, radon reaches the equilibrium concentration more quickly than moisture does. As relative humidity increases, η decreases, but the radon equilibrium concentration increases. The values of η are bigger for those smaller particle sizes with the same type of activated charcoal. The results of this paper are useful for designing activated charcoal systems at indoor environmental conditions and predicting η for radon mitigation applications.
•Prediction of radon removal efficiency for radon mitigation applications with activated charcoal systems.•Characteristics of radon mitigation for the flow-through activated charcoal system.•Evaluation of the effectiveness of radon mitigation for activated charcoal systems.•Enables future application to design activated charcoal systems for radon mitigation.
A
bstract
JUNO is a massive liquid scintillator detector with a primary scientific goal of determining the neutrino mass ordering by studying the oscillated anti-neutrino flux coming from two nuclear ...power plants at 53 km distance. The expected signal anti-neutrino interaction rate is only 60 counts per day (cpd), therefore a careful control of the background sources due to radioactivity is critical. In particular, natural radioactivity present in all materials and in the environment represents a serious issue that could impair the sensitivity of the experiment if appropriate countermeasures were not foreseen. In this paper we discuss the background reduction strategies undertaken by the JUNO collaboration to reduce at minimum the impact of natural radioactivity. We describe our efforts for an optimized experimental design, a careful material screening and accurate detector production handling, and a constant control of the expected results through a meticulous Monte Carlo simulation program. We show that all these actions should allow us to keep the background count rate safely below the target value of 10 Hz (i.e.
∼
1 cpd accidental background) in the default fiducial volume, above an energy threshold of 0.7 MeV.
The OSIRIS detector is a subsystem of the liquid scintillator filling chain of the JUNO reactor neutrino experiment. Its purpose is to validate the radiopurity of the scintillator to assure that all ...components of the JUNO scintillator system work to specifications and only neutrino-grade scintillator is filled into the JUNO Central Detector. The aspired sensitivity level of
10
-
16
g/g
of
238
U
and
232
Th
requires a large (
∼
20
m
3
) detection volume and ultralow background levels. The present paper reports on the design and major components of the OSIRIS detector, the detector simulation as well as the measuring strategies foreseen and the sensitivity levels to U/Th that can be reached in this setup.
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