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The Back-n white neutron source at the China Spallation Neutron Source (CSNS) provides neutrons in the continuous energy region from 0.5 eV to 200 MeV. A spectrometer named Light charged Particle Detector Array (LPDA) is designed for the study of (n, lcp) reactions at Back-n. The main detector of the LPDA spectrometer, a 16-unit ΔE-ΔE-E telescope array, is composed of two arrays of 8-unit ΔE-ΔE-E telescope. Each telescope unit consists of a Low-Pressure Multi-Wire Proportional Chamber (LPMWPC), a Si-PIN detector, and a CsI(Tl) scintillator detector. In 2021, a neutron-proton (n-p) scattering reaction cross-section measurement experiment was accomplished as the first experiment of the telescope array. Protons can be clearly identified in the ΔE-E spectrum (LPMWPC + Si-PIN) and the ΔE-E spectrum (Si-PIN + CsI(Tl)). Cross sections of the n-p scattering reaction in the neutron energy range of several MeV are extracted. The ΔE-E method also provides new measurement opportunities for many-body neutron induced light charged-particle emission reactions.

According to the recent World Health Organization (WHO) classification, appendiceal mucinous tumours include low-grade mucinous appendiceal neoplasm (LAMN), high-grade mucinous appendiceal neoplasm (HAMN), and mucinous adenocarcinoma. LAMN is almost the rarest appendiceal tumor with an incidence of about 0.7–1.7%. A ruptured appendiceal mucinous neoplasm can lead to progressive accumulation of mucus in the peritoneal cavity, resulting in pseudomyxoma peritoneum (PMP) with the chance of metastasis and recurrence. Appendiceal neuroendocrine tumor (ANET) is the most frequent appendiceal lesion. A collision between LAMN and ANET is an exceedingly rare condition. So far, evaluating the literature, just 10 cases of collision LAMN and ANET have been reported. Here, we report a case of pulmonary pleura metastasis from LAMN with ANET. Our work will help to improve the accuracy of the diagnosis and avoid misdiagnosis.

Goblet cell adenocarcinoma (GCA) is a rare tumor, and it is characterized by its unique combination of neuroendocrine and adenocarcinoma. GCA occurs mainly in the appendix. Currently, there is no primary GCA of the rectum in the 2019 World Health Organization classification of colorectal tumors. Here, we report a case of the primary GCA of the rectum that combined examinations via histological morphology, immunohistochemistry, transmission electron microscopy (TEM), and molecular detection. We demonstrate that this tumor is the primary rectum GCA for the first time worldwide. Our work will help to improve the diagnosis of the primary GCA of the rectum and avoid misdiagnosis and mistreatment.

SMARCA4-deficient undifferentiated uterine sarcoma (SDUS) is a highly invasive single-gene malignant tumour caused by mutations in the SMARCA4 gene. SDUS has a poor prognosis and has no established treatment scheme at present. What's more, there is no relevant research on the role of immune microenvironment analysis in SDUS worldwide. Here, we report a case of SDUS that combined examinations via morphology, immunohistochemistry, immunofluorescence, and molecular detection and analysed the immune microenvironment of SDUS for the first time. Therefore, our report will help in the diagnostic awareness of SDUS.

This study was carried out to investigate the hydrogeochemical characteristics, processes, and factors that control the groundwater chemistry in Jinghui canal irrigation district of China. Water qu...

A Muon station for science, technology and industry project will be constructed at China Spallation Neutron Source. The Phase I project will provide a surface muon beam with a pulse width of 130 ns at a rate over 105 µ+/pulse. Beam intensity is the key design parameter of this project. Accurate measurement of the intensity is also essential for the calibration of the µSR spectrometer. The key to the surface muon intensity measurement is to distinguish background positrons from muons. A double-stacked scintillator detector based on PMT readout scheme has been proposed, which can determine the intensity of muons and background positrons by using pulse shape discrimination method. Detailed description of the detector principle and simulated results will be presented.

A Muon station for sciEnce, technoLOgy and inDustrY (MELODY) has been listed in the China Spallation Neutron Source upgrade plan, and the infrastructure construction is scheduled to start by the end of 2022. The 1.6 GeV double-pulsed proton bunch will be extracted from the Rapid Cycling Synchrotron (RCS) ring to a stand-alone target station. One surface muon and one decay muon beamline are designed to provide multi-terminals for applications. In this report, we describe the design of MELODY and prospect for future applications.

235U and 238U are very important isotopes in the nuclear energy system. Their neutron-induced fission cross sections have been measured intensively and evaluated as standard up to 200 MeV. However, as a matter of fact, the experimental data in the high-energy region are scarce. This work reports the measurement of 235, 238U(n, f) cross sections relative to n-p scattering performed at the China Spallation Neutron Source (CSNS) back-streaming neutron facility (Back-n). Preliminary results of 235, 238U(n, f) cross sections from 10 to 66 MeV are obtained, which are generally following the shape of the IAEA standard. However, significant discrepancies are observed at some given energies, which will be further studied.

To predict the soft error rate for applications, it is essential to study the energy dependence of the single-event-upset (SEU) cross-section. In this work, we present a direct measurement of the SEU cross-section with the Back-n white neutron source at the China Spallation Neutron Source. The measured cross section is consistent with the soft error data from the manufacturer and the result suggests that the threshold energy of the SEU is about 0.5 MeV, which confirms the statement in Iwashita’s report that the threshold energy for neutron soft error is much below that of the (n, α) cross-section of silicon. In addition, an index of the effective neutron energy is suggested to characterize the similarity between a spallation neutron beam and the standard atmospheric neutron environment.

The back-streaming white neutron source (Back-n) at China Spallation Neutron Source (CSNS), which has excellent energy spectrum and good time resolution, provides superior conditions for neutron induced light charged particle tracking experiment. To track light charged particles, CSNS has proposed a project named Multi-purpose Time Projection Chambers (MTPC) and completed a 1519-channel prototype. A multi-channel readout system based on Switched Capacitor Arrays (SCA) waveform sampling ASIC was designed to meet the requirements of the prototype MTPC. This paper presents the structure of this readout system and the results of the beam test with MTPC at CSNS. Time of Flight spectrum of neutron beam and 3D-track of neutron induced light charged particles were successfully reconstructed. These test results prove the feasibility of large-scale MTPC.

Aluminum and its alloys are widely used in the nuclear industry. Therefore, it is essential to precisely measure and accurately know the neutron total cross section of aluminum in the wider energy region. The measurement is performed by using the transmission method at the Back-n White Neutron Source of CSNS. Two aluminum samples 70 mm in diameter and thicknesses of 40 and 60 mm, respectively, were positioned at 55 m from the neutron source. The transmission detector consisted of a multi-layer fast fission chamber loaded with $$^{235}$$ U and $$^{238}$$ U, and it was located at the 76-m measurement station. By applying the time-of-flight technique, it was possible to extract the n+ $$^{27}$$ Al total cross section in a wide energy region, from 1 eV to 20 MeV, after the correction for the double-bunch mode of the CSNS accelerator. The total cross sections obtained with the two Al samples are consistent and the results obtained with the $$^{235}$$ U fission cells are in good agreement with that with $$^{238}$$ U in the energy range of 1–20 MeV. The uncertainty of neutron total cross section measured with $$^{235}$$ U for 40 mm and 60 mm thick aluminum is 0.7–22.3% and 0.6–12.4% in the energy range of 10 keV–20 MeV. Results are in fair agreement with respect to previous data and evaluations.

Silicon microstrip detectors with floating strips have nonuniform charge collection efficiency. This nonuniformity depends on the incident position and incident angle and should be corrected during charge reconstruction. A novel charge reconstruction algorithm, called the charge sharing algorithm, is introduced to correct this nonuniformity. This algorithm assumes that the nonuniformity in charge collection efficiency is due to charge sharing through the capacitors and resistors of silicon microstrip detectors. This charge sharing assumption is tested in this paper using electrical characterization and SPICE simulation.

Cellular labelling is possible to offer significant information after transplantation for the purpose of determining stem cell therapy's efficacy. According to the research, it has been reported that graphene oxide quantum dots (GOQDs) are a kind of healthy biological labelling agent for stem cells which show little cytotoxicity. GOQDs' interactions have been examined on the dental pulp stem cells (hDPSCs) of human beings for the purpose of investigating GOQD's biocompatibility and uptake and explored GOQDs' effects on hDPSCs' metabolic activity and the proliferation. According to the outcomes, GDQDs have been accepted by hDPSCs in a time-dependent and concentration-dependent behaviour. Moreover, no important changes have been discovered within hDOPSCs' proliferation, viability as well as metabolic activity after treatment with GOQDs. Therefore, such resources have shown that GOQDs can be multifunctional agents for cell therapy, drug delivery as well as cell imaging and also as outstanding candidates for labelling stem cells.

This paper introduces sparsity in the traditional fuzzy clustering framework and presents two novel clustering methods. The first one is called deviation-sparse fuzzy c-means (DSFCM). When spatial correlation is encountered, the second method is proposed, which is called deviation-sparse fuzzy c-means with neighbor information constraint (DSFCM_N). The contributions of this paper are threefold. First, the theoretical values of data, estimated from the measured values, are utilized in the clustering process. This could acquire more accurate cluster centers than the traditional fuzzy c-means. Second, by imposing sparsity on the deviations between measured values and theoretical values, DSFCM and DSFCM_N could identify noise and outliers. Finally, with the constraint of neighbor information, the estimation of the deviations between measured values and theoretical values of data would be more reliable than only considering the data itself. Experiments performed on artificial and real-world images show that DSFCM_N is effective and efficient, and thus more competitive than other fuzzy clustering methods.

The relative differential cross sections of the $$^{1}\hbox {H}(n, \,el)$$ reaction have been measured at the China Spallation Neutron Source (CSNS) Back-n white neutron source. A low-density polyethylene sample and a graphite foil were prepared for the foreground and background measurements, respectively. The charged particles were detected using the $${\vartriangle }E-E$$ telescope array of the Light-charged Particle Detector Array (LPDA) system. With 10 $${\vartriangle }E-E$$ telescopes, the relative differential cross sections of the $$^{1}\hbox {H}(n, \,el)$$ reaction were obtained from 70 $$^{\circ }$$ to 160 $$^{\circ }$$ in the center-of-mass system in the neutron energy ( $$E_{\mathrm{n}}$$ ) range from 6.14 to 52.48 MeV (23 energy points). The present work was the first experiment using the $${\vartriangle }E-E$$ telescope array of the LPDA system at CSNS. The present results are in good agreement with previous measurements, evaluations and theoretical calculations. Furthermore, this work is the first measurement in the 6.52 MeV $$\le E_{\mathrm{n}} \le $$ 9.09 MeV, 10.57 MeV $$\le E_{\mathrm{n}} \le $$ 12.43 MeV, and 18.05 MeV $$\le $$ $$E_{\mathrm{n}} \le $$ 20.05 MeV regions.

Back-streaming neutrons from the spallation target of the China Spallation Neutron Source (CSNS) that emit through the incoming proton channel were exploited to build a white neutron beam facility (the so-called Back-n white neutron source), which was completed in March 2018. The Back-n neutron beam is very intense, at approximately 2*10^7 n/cm^2/s at 55 m from the target, and has a nominal proton beam with a power of 100 kW in the CSNS-I phase and a kinetic energy of 1.6 GeV and a thick tungsten target in multiple slices with modest moderation from the cooling water through the slices. In addition, the excellent energy spectrum spanning from 0.5 eV to 200 MeV, and a good time resolution related to the time-of-flight measurements make it a typical white neutron source for nuclear data measurements; its overall performance is among that of the best white neutron sources in the world. Equipped with advanced spectrometers, detectors, and application utilities, the Back-n facility can serve wide applications, with a focus on neutron-induced cross-section measurements. This article presents an overview of the neutron beam characteristics, the experimental setups, and the ongoing applications at Back-n., Comment: 11 pages, 9 figures

The capture cross sections of the 169Tm reaction were measured at the back streaming white neutron beam line (Back-n) of the China Spallation Neutron Source (CSNS) using four C6D6 liquid scintillation detectors. The background subtraction, normalization, and correction were carefully considered in the data analysis to obtain accurate cross sections. For the resonance at 3.9 eV, the R-matrix code SAMMY was used to determine the resonance parameters with the internal normalization method. The average capture cross sections of 169Tm for energy between 30 and 300 keV were extracted relative to the 197Au reaction. The measured cross sections of the 169Tm reaction were reported in logarithmically equidistant energy bins with 20 bins per energy decade with a total uncertainty of 5.4% – 7.0% in this study and described in terms of average resonance parameters using a Hauser-Feshbach calculation with fluctuations. The point-wise cross sections and the average resonance parameters showed fair agreement with the evaluated values of the ENDF/B-VIII.0 library in the energy region studied.

A simple method for measuring the electron drift velocity in gases with a given electric field using a grid ionization chamber is proposed and demonstrated. By collimating incident α particles that are perpendicular to the electric field, the drift velocity can be derived easily using the electron drift distance from primary ionization to a grid divided by the time interval between the cathode and anode signal starting times. These experimental settings can avoid additional signal processing of signals and reduce the effect of electron diffusion. Using this method, the measurement of electron drift velocities in 90% Ar + 10% CO2 is presented. Measured results agree well with the simulated values and with existing experimental results.

Hydrophone is an important part of sonar. But the output signal from hydrophone is weak, so hydrophone and signal conditioning circuit are usually used together. In this paper, a design scheme of signal conditioning circuit is proposed. After experimental verification, this method can obtain programmable gain of 1–1000 times. The filter frequency of band-pass filter can be set according to the requirement. And the corresponding indicators can meet the needs of hydrophone for signal conditioning.

The DArk Matter Particle Explorer (DAMPE) is a space-borne particle detector designed to probe electrons and gamma-rays in the few GeV to 10 TeV energy range, as well as cosmic-ray proton and nuclei components between 10 GeV and 100 TeV. The silicon–tungsten tracker–converter is a crucial component of DAMPE. It allows the direction of incoming photons converting into electron–positron pairs to be estimated, and the trajectory and charge (Z) of cosmic-ray particles to be identified. It consists of 768 silicon micro-strip sensors assembled in 6 double layers with a total active area of 6.6 m 2 . Silicon planes are interleaved with three layers of tungsten plates, resulting in about one radiation length of material in the tracker. Internal alignment parameters of the tracker have been determined on orbit, with non-showering protons and helium nuclei. We describe the alignment procedure and present the position resolution and alignment stability measurements.

The white neutron beamline at the China Spallation Neutron Source will be used mainly for nuclear data measurements. It will be characterized by high flux and broad energy spectra. To exploit the beamline as a neutron imaging source, we propose a liquid scintillator fiber array for fast neutron resonance radiography. The fiber detector unit has a small exposed area, which will limit the event counts and separate the events in time, thus satisfying the requirements for single-event time-of-flight (SEToF) measurement. The current study addresses the physical design criteria for ToF measurement, including flux estimation and detector response. Future development and potential application of the technology are also discussed., 4 figures

Premise of study Leaf area and dry mass are crucial for plant metabolic performance. The "diminishing returns" hypothesis predicts that leaf area will scale less than one with respect to leaf dry mass, indicating that the cost of light interception increases with leaf area. However, it remains unclear whether and how this scaling relationship varies among species growing in different environments. Methods More than 2000 measurements from five bamboo species adapted to high and low light and growing at different elevations in Wuyi Mountains, Southeast China, were used to explore how the leaf area vs. dry mass scaling relationship was affected by light and elevation. Key results The data indicate that (1) the normalization constants for leaf area vs. dry mass were positively but not significantly correlated with increasing leaf size and that (2) the scaling exponents remained numerically invariant among all five bamboo species, with a common slope of 0.85. Standardized major axis (SMA) analyses and comparisons of 95% confidence intervals also showed that the numerical values of the scaling exponents did not differ regardless of elevation and were similar between shaded and unshaded adapted species, whereas the numerical values of the normalization constants increased with decreasing light. Conclusions The data collected for all five bamboo species are consistent with the "diminishing returns" hypothesis, i.e., the scaling exponents governing the leaf area vs. dry mass scaling relationship are less than one within and across species and are insensitive to light conditions or elevation.

Differential and angle-integrated cross sections for the $^{10}$B($n, {\alpha}$)$^{7}$Li, $^{10}$B($n, {\alpha}$$_{0}$)$^{7}$Li and $^{10}$B($n, {\alpha}$$_{1}$)$^{7}$Li$^{*}$ reactions have been measured at CSNS Back-n white neutron source. Two enriched (90%) $^{10}$B samples 5.0 cm in diameter and ~85.0 ${\mu}$g/cm$^{2}$ in thickness each with an aluminum backing were prepared, and back-to-back mounted at the sample holder. The charged particles were detected using the silicon-detector array of the Light-charged Particle Detector Array (LPDA) system. The neutron energy E$_{n}$ was determined by TOF (time-of-flight) method, and the valid ${\alpha}$ events were extracted from the E$_{n}$-Amplitude two-dimensional spectrum. With 15 silicon detectors, the differential cross sections of ${\alpha}$-particles were measured from 19.2{\deg} to 160.8{\deg}. Fitted with the Legendre polynomial series, the ($n, {\alpha}$) cross sections were obtained through integration. The absolute cross sections were normalized using the standard cross sections of the $^{10}$B($n, {\alpha}$)$^{7}$Li reaction in the 0.3 - 0.5 MeV neutron energy region. The measurement neutron energy range for the $^{10}$B($n, {\alpha}$)$^{7}$Li reaction is 1.0 eV $\le$ En < 2.5 MeV (67 energy points), and for the $^{10}$B($n, {\alpha}$$_{0}$)$^{7}$Li and $^{10}$B($n, {\alpha}$$_{1}$)$^{7}$Li$^{*}$ reactions is 1.0 eV $\le$ En < 1.0 MeV (59 energy points). The present results have been analyzed by the resonance reaction mechanism and the level structure of the $^{11}$B compound system, and compared with existing measurements and evaluations., Comment: 19 pages, 34 figures, to be published in Chinese Physics C

Weighted Schatten p-norm minimization (WSNM) has been used successfully for noisy-free image completion. However, WSNM can introduce extra artifacts if the observed entries of image contain noise. In this paper, we present a novel WSNM-based method for noisy image completion, which incorporates both local smoothness and nonlocal self-similarity in a unified framework. More concretely, the analysis operator is utilized to ensure local smoothness and the nonlocal statistical modeling (NLSM) is adopted to constrain nonlocal self-similarity while WSNM is effective for completing the missing entries. To make the proposed method tractable and robust, the alternating direction method of multipliers (ADM-M) is employed to solve the above inverse problem. Experimental results show the effectiveness of the proposed method for noisy image completion.

To verify the performance of the neutron total cross-sectional spectrometer, the neutron total cross section of carbon is initially measured in the energy range of 1 eV to 20 MeV using the time-of-flight method. The measurement is performed at the Back-n white neutron source with a 76-m time-of-flight path using the China Spallation Neutron Source. A multilayer fast fission chamber with 235U and 238U is employed as the neutron detector. The diameter and thickness of the natural graphite sample are 70 mm and 40 mm, respectively. Signal waveforms are collected using a data acquisition system. Off-line data processing was used to obtain the neutron time-of-flight spectra and transmissions. The uncertainty of the counting statistics is generally approximately 3% for each bin in the energy range of 1–20 MeV. It is determined that the results for the neutron total cross section of carbon obtained using 235U cells are in good agreement with the results obtained using 238U cells within limits of statistical uncertainty. Moreover, the measured total cross sections show good agreement with the broadening evaluated data.