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This study investigated both the disturbance electric fields processes including the Interplanetary Electric Field (IEFy) to low-latitude, known as prompt penetration electric field (PPEF) and the disturbance dynamo electric field (DDEF), and their effects on ionospheric TEC and scintillations over south China during four storms of 17 March 2015, 15 July 2012, 7 October 2015 and 20 December 2015. GPS ionospheric and magnetometer data were derived from receiver stations at Guangzhou and Shenzhen, and at Guangdong Zhaoqin (GZH) and equatorial station Dalat, respectively. Results presented that cases of the eastward PPEF on dayside with durations of 3 and 8 h were identified during storm main phases of 17 March 2015 and of 20 December 2015 respectively. DDEFs were found to dominate on nightside during the three main storm phases other than storm of 15 July 2012, and on dayside during the recovery storm phase of 21 December 2015. The responses of positive TEC deviation to the eastward PPEF on dayside were identified during the storm main phase of 20 December 2015 rather than during the storm of 17 March 2015, which showed longitudinal, latitudinal and seasonal dependences as compared to the previous studies. During the storm of 15 July 2012, positive TEC deviations with no response to the eastward PPEF on dayside were identified. Negative TEC deviation responses to the DDEF on dayside were seen during all four storm recovery phases. GPS ionospheric scintillations (S 4 ≥ 0.4) dominated in the equinox months before the occurrences of four storms, but were inhibited during the storm of 17 March 2015 over south China, which was attributed to the inhibitions of irregularities caused scintillations. [ABSTRACT FROM AUTHOR]

Plasma irregularity in the equatorial and low-latitude ionosphere, which leads to ionospheric scintillation, can threaten the operation of radio-based communication and navigation systems. A method for forecasting scintillation activity is still pending. In this study, we examined the performance of ionospheric parameters, including the critical frequency (foF2), peak height of the F2-layer (hmF2), scale height (Hm) and virtual height (h'F), around local sunset from ground-based ionosonde observations, and also the characteristics of Equatorial Ionization Anomaly (EIA) derived from Gravity Recovery and Climate Experiment (GRACE) observations in equinoctial months (March–April and September–October) during high solar activities (2012–2013) at a low-latitude station at Sanya (18.3° N, 109.6° E; dip lat.: 12.8° N), China. Furthermore, the simplified linear growth rate of Rayleigh–Taylor (R–T) instability inferred from ionosonde measurements and EIA strength derived from GRACE observations were used to estimate the day-to-day occurrence of post-sunset scintillation. The results indicate that it is not adequate to determine whether scintillation in a low-latitude region would occur or not based on one ionospheric parameter around sunset. The simplified growth rate of R–T instability can be a good indicator for the day-to-day occurrence of scintillation, especially in combination with variations in EIA strength. An index including the growth rate and EIA variations for the prediction of the post-sunset occurrence of irregularity and scintillation is proposed; the overall prediction accuracy could be about 90%. Our results may provide useful information for the development of a forecasting model of the day-to-day variability of irregularities and scintillation in equatorial and low-latitude regions. [ABSTRACT FROM AUTHOR]

Ionospheric scintillation could seriously disrupt the signal tracking of the global navigation satellite systems (GNSS), further causing positioning accuracy degradation or unavailability. BeiDou navigation satellite system (BDS), a newly developed GNSS by China, has begun to provide global positioning, navigation, and timing service. The objective of the present study is to investigate the effects of ionospheric scintillation on BDS‐2 and BDS‐3 multi‐frequency signals. Ionospheric scintillation monitor receiver data from four monitors in Brazil were collected from October 2021 to May 2022. The results illustrate that S4(B2) and S4(B3) linearly increase with S4(B1) for S4(B1) ≤ 0.6, which is consistent with weak scattering theories, and average experimental ratios of S4(B2)/S4(B1), S4(B3)/S4(B1), and S4(B2)/S4(B3) are less than corresponding theoretical ones by 6.1%, 4.4%, and 1.9%, respectively. Meanwhile, as S4 values increase, lower‐frequency scintillation saturates earlier than higher ones, and the probability of ionospheric scintillation events on B2 and B3 signals is approximately twice (S4 ≥ 0.7) as B1 signals in the equatorial ionization anomaly (EIA) regions. To alleviate the undesirable effects of missing data on GNSS positioning, we first investigate the inter‐frequency relationship and distribution probability of two significant spectral parameters, that is, T (the spectral strength of the phase noise at 1 Hz) and p (the spectral slope of the phase power spectral density) in the tracking jitter model among three BDS frequencies. Results show that the performances among B1, B2, and B3 frequencies have a higher correlation respectively, and their values for B2 and B3 signals are more susceptible to be impacted by ionospheric scintillation. Plain Language Summary: Ionospheric scintillation seriously affects the precision and continuity of the global navigation satellite systems (GNSS) signals and causes positioning accuracy degradation or unavailability. Therefore, it is essential to study the impacts of ionospheric scintillation on the GNSS receiver performance. This study first investigates the inter‐frequency relation of the amplitude scintillation index S4 for B1, B2, and B3 signals from BDS‐2 and BDS‐3 satellites based on the Ionospheric scintillation monitor receiver data at four geomagnetic latitudes in the Brazilian territory. Furthermore, the distribution probability and inter‐frequency relationship of two significant phase spectral parameters of the tracking jitter model, which are widely applied in GNSS positioning solutions, are also presented among three BDS frequencies. All investigations conducted within this contribution show agreement with earlier work in ionospheric scintillation and provide supportive and detailed numerical statements and comparisons. Key Points: The inter‐frequency relation of the amplitude scintillation index for multi‐frequency signals from BDS‐2 and BDS‐3 satellites is displayedThe probability of the ionospheric scintillation events on B2 and B3 signals is approximately twice (S4 ≥ 0.6) as B1 signals in EIA regionsThe spectral parameters p and T of B2 and B3 signals are more susceptible to be affected by ionospheric scintillation [ABSTRACT FROM AUTHOR]

In nuclear astrophysics, the nuclides 151 Eu and 153 Eu are both in the path of the s-process, and their (n, γ ) cross sections are important input parameters for the calculation of the nuclear astrophysics network. According to the EXFOR database, the neutron capture cross section of natural europium in the resonance region has not been fully measured. The (n, γ ) cross section of nat Eu was measured using the time-of-flight (TOF) technique at the Back-n white neutron source facility of the China Spallation Neutron Source (CSNS) in the 1 eV–to 500 keV range. Four C 6 D 6 liquid scintillator detectors and pulse height weighting techniques were used to measure prompt γ rays and analyze the data. The results of the analysis were compared with the evaluated data of ENDF/B-VIII.0 and JENDL-5.0. It shows that there are some differences between the measurement results and different evaluated data libraries. The resonance parameters of 151 Eu and 153 Eu were extracted in the 1 eV–150 eV region using the R-Matrix code SAMMY. The accurate Maxwellian-averaged capture cross section (MACS) is derived over the temperature range of the s-process nucleosynthesis model. The result shows that at kT=30 keV, the MACS value of 151 Eu is 3417 ± 297 mb and the value of 153 Eu is 2718 ± 237 mb. [ABSTRACT FROM AUTHOR]

The Serappis (SEarch for RAre PP-neutrinos In Scintillator) project aims at a precision measurement of the flux of solar pp neutrinos on the few-percent level. Such a measurement will be a relevant contribution to the study of solar neutrino oscillation parameters and a sensitive test of the equilibrium between solar energy output in neutrinos and electromagnetic radiation (solar luminosity constraint). The concept of Serappis relies on a small organic liquid scintillator detector (∼ 20 m 3 ) with excellent energy resolution (∼ 2.5% at 1 MeV), low internal background and sufficient shielding from surrounding radioactivity. This can be achieved by a minor upgrade of the OSIRIS facility at the site of the JUNO neutrino experiment in southern China. To go substantially beyond current accuracy levels for the pp flux, an organic scintillator with ultra-low 14 C levels (below 10 - 18 ) is required. The existing OSIRIS detector and JUNO infrastructure will be instrumental in identifying suitable scintillator materials, offering a unique chance for a low-budget high-precision measurement of a fundamental property of our Sun that will be otherwise hard to access. [ABSTRACT FROM AUTHOR]

The Jiangmen Underground Neutrino Observatory (JUNO) is a multipurpose experiment under construction in southern China; detector completion is expected in 2023. JUNO is a homogeneous calorimeter consisting of a target mass of 20 kt of an organic liquid scintillator, aiming to detect antineutrinos from reactors to investigate the neutrino oscillation mechanism. The scintillation and Cerenkov light emitted after the interaction of antineutrinos with the liquid scintillator is seen by a compound system of 20 inch large PMTs and 3 inch small PMTs, with a total photo-coverage of 78%. A dual-calorimetry technique is developed based on the presence of the two independent photosensor systems which are characterized by different average light level regimes, resulting in different dynamic ranges. Thanks to this novel technique, an unprecedented high light yield, and in combination with a comprehensive multiple-source and multi-position calibration campaign, JUNO is expected to reach energy-related systematic uncertainties below 1% and an effective energy resolution of 3% at 1%, required for the neutrino oscillation analysis. [ABSTRACT FROM AUTHOR]

To monitor the natural radiation level in a River region in Southern China, an investigation was conducted into the terrestrial γ dose rate and soil Rn concentration. The in-situ survey took place at 541 points, using portable γ dose rate scintillators and radon detectors. The mean γ dose rate and the soil Rn concentration have been determined to be 100 ± 40 nGy h−1 and 4000 ± 3000 Bq m−3, respectively. The high radiation spots were observed at the eastern edge and the southwest corner of the study region, which could be attributed to the granite rocks that dominated the areas. [ABSTRACT FROM AUTHOR]

Precise measurement under high counting rates has been a major challenge for γ -ray spectroscopy, where signals generally pile up with each other and their characteristic values are deeply coupled. An off-line pile-up pulse recovery algorithm based on template matching is developed for LaBr 3 scintillation detectors and has been applied to data from China Spallation Neutron Source (CSNS) Back-n white neutron beamline. As an improvement to the traditional Template Matching methods, the predetermined template shape is associated with pulse amplitudes, which is found crucial to achieve the best fitting results. Moreover, a universal strategy of setting the initial values of fitting allows to resolve signals that are separated in time by less than the characteristic rise time. Processing of simulated pulses demonstrates that the lower limit of interval to distinguish successive events is 10 ns, which is a significant improvement to the previous works. The algorithm performs well under a counting rate of 6 × 1 0 7 s−1, and is still effective up to 1 0 8 s−1. Analysis of experimental data indicates that this algorithm recovers over 98% count yield under a counting rates of no more than 4 × 1 0 6 s−1 in this work, providing a more reliable approach to deduce neutron-induced reaction cross sections. [ABSTRACT FROM AUTHOR]

The Jiangmen Underground Neutrino Observatory (JUNO) is a state-of-the-art liquid scintillator-based neutrino physics experiment under construction in South China. To reduce the background from external radioactivities, a water Cherenkov detector composed of 35 kton ultra-pure water and 2,400 20-inch photomultiplier tubes is developed. Even after specialized treatment, ultra-pure water still contains trace levels of radioactive elements that can contribute to the detector background. Among which 222Rn is particularly significant. To address this, an online radon removal system based on the JUNO prototype has been developed. By integrating micro-bubble generators to enhance degasser's radon removal efficiency, the radon concentration in water can be reduced to 1 mBq/m3 level, meeting the stringent requirements of JUNO. Additionally, a highly sensitive online radon concentration measurement system capable of detecting concentrations ∼ 1 mBq/m 3 has been developed to monitor the radon concentration in water. In this paper, the details regarding both systems will be presented. [ABSTRACT FROM AUTHOR]

Due to the shortage of the 3He gas and its rapidly increasing price, scintillator detectors, the advantages of which are high spatial resolution and capability of detection in real time, become widely used in many neutron instruments. In this work, a position-sensitive neutron detector consisting of a 6LiF/ZnS scintillation screen and a silicon photomultiplier array linked to a capacitive network to detect the positions of incident neutrons, is constructed and tested. To evaluate the detector performance, a series of neutron beam experiments with the detector prototype were performed in the BL20 at the China Spallation Neutron Source. The spatial resolution was measured, and the energy-selective neutron imaging and Bragg edge measurements of a 316L stainless steel sample were performed. A sub-millimeter spatial resolution could be obtained for the detector prototype under study. The detector with such a high spatial resolution is promising for applications in neutron scattering experimental installations, especially for neutron single-crystal diffractometers. [ABSTRACT FROM AUTHOR]

A 128-channel positron detection system will be constructed at Experimental Muon Source (EMuS) of China Spallation Neutron Source (CSNS) to conduct muon spin rotation/relaxation/resonance ($\mu $ SR) measurements. Each detector channel consists of a scintillator, a light guide, and a photomultiplier tube (PMT). The long light guide is bent to an “L” shape to propagate optical photons from the scintillator to the PMT. A series of Geant4 simulations and experiments has been performed to optimize the light collection performance of the L-bent detector. Geometry deformation induced by the bending process has been well modeled. Simulation results agree with the experimental tests. Accordingly, a novel hybrid wrapping method (scintillator with polytetrafluoroethylene (PTFE) and light guide with aluminum tape) has been developed to improve the amplitude of detector signals greatly. Compared to wrapping the detector with merely PTFE tapes or aluminum tapes, this method leads to an enhancement in light collection efficiency of 73% or 14%, respectively. Two optimally manufactured prototype detectors using the novel wrapping method have been tested at the ISIS Muon Facility. The beam tests demonstrated that the L-bent detectors can precisely measure the behavior of muon spins inside samples. Therefore, the L-bent detector design is competent for $\mu $ SR applications at CSNS/EMuS. [ABSTRACT FROM AUTHOR]

The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose, large size, liquid scintillator experiment under construction in China. JUNO will perform leading measurements detecting neutrinos from different sources (reactor, terrestrial and astrophysical neutrinos) covering a wide energy range (from 200 keV to several GeV). This paper focuses on the design and development of a test protocol for the 20-inch PMT underwater readout electronics. The protocol has been employed for 10 months during the mass production and validation of all the electronics that will be installed in JUNO. A total number of 6950 electronic boards were tested with an acceptance yield of 99.1 %. [ABSTRACT FROM AUTHOR]

Two inorganic scintillator detectors consisting of Yb:YAG scintillators and photomultiplier tubes, and an oscilloscope were used to studied the neutron sensitivities of Yb:YAG scintillators at the China Spallation Neutron Source (CSNS) Back-n white neutron source. The relative neutron sensitivity curves of two Yb:YAG scintillators in the energy region between 0.5 and 20 MeV were obtained for the first time. As the measured relative neutron sensitivity curves of Yb:YAG scintillators cannot be verified by the Monte Carlo method and there was no referable data, the neutron sensitivity curve of a ST401 scintillator was also studied in the same method and a Geant4 simulation of ST401 scintillator was conducted to verify the experiment method in this paper. The result showed that the experimental and simulation results were approximately consistent between 17–20 MeV, and agreed well between 1–17 MeV. A comparison between the experimental result and references of ST401 scintillator was also applied and the result showed that the curve tendency of the experimental result and references was matched. The above results imply that the measured relative neutron sensitivity curves and the experimental method used herein were reliable. It also demonstrated the feasibility of studying the neutron sensitivity of inorganic scintillator based on the white neutron source. [ABSTRACT FROM AUTHOR]

The FIssion Neutron spectrum Detector Array (FINDA) has been designed for measurement of prompt fission neutron spectrum on the Back-n beam line at the China Spallation Neutron Source (CSNS). In order to test the neutron- γ discrimination performance of the EJ301 scintillator that will be used as a detector unit in the FINDA, a comparative study using three conventional digital pulse shape discrimination (PSD) methods has been carried out. An Am–Be source has been used to generate the mixed neutron- γ radiation and the waveform data has been obtained with a fast digitizer. Pulse interpolation, baseline restoration and pulses pile-up rejection have been applied for digital pulse processing. Charge comparison (CC) method and simplified charge comparison(SCC) method show a better capability of neutron- γ discrimination than rise time comparison(RTC) method over the entire energy range. Rise time comparison method needs a very fast digitizer or pulse interpolation to improve the PSD ability. The analysis of neutron- γ discrimination performance of the EJ301 scintillator provides a strong technical support for fast neutron measurement using the FINDA at CSNS. • The neutron- γ discrimination performance of an EJ301 scintillator that will used as a detector unit in the FINDA spectrometer at CSNS has been characterized. • A comparative study using three conventional digital pulse shape discrimination (PSD) methods has been carried out. • Charge comparison (CC) method and simplified charge comparison (SCC) method show a better capability of neutron- γ discrimination than rise time comparison (RTC) method over the entire energy range. • With the current test we discussed the results in view of applications on the Back-n beam line at CSNS and the analysis provides a strong technical support for fast neutron measurement using the FINDA. [ABSTRACT FROM AUTHOR]