NνDEx-100 conceptual design report

Observing nuclear neutrinoless double beta (0vββ) decay would be a revolutionary result in particle physics.Observing such a decay would prove that the neutrinos are their own antiparticles,help to study the absolute mass of neutrinos,explore the origin of their mass,and may explain the matter-antimatter asymmetry in our universe by lepton number violation.We propose developing a time projection chamber (TPC) using high-pressure ^(82)SeF_(6) gas and Topmetal silicon sensors for readout in the China Jinping Underground Laboratory (CJPL) to search for neutrinoless double beta decay of82Se,called the NvDEx experiment.Besides being located at CJPL with the world’s thickest rock shielding,NvDEx combines the advantages of the high Qββ(2.996 MeV) of82Se and the TPC’s ability to distinguish signal and background events using their different topological characteristics.This makes NvDEx unique,with great potential for low-background and high-sensitivity 0 vββsearches.NvDEx-100,a NvDEx experiment phase with 100 kg of SeF_(6)gas,is being built,with plans to complete installation at CJPL by 2025.This report introduces 0 vββ physics,the NvDEx concept and its advantages,and the schematic design of NvDEx-100,its subsystems,and background and sensitivity estimation.

Analyzing the surface passivity effect of germanium oxynitride:a comprehensive approach through first principles simulation and interface state density

High-purity germanium(HPGe)detectors,which are used for direct dark matter detection,have the advantages of a low threshold and excellent energy resolution.The surface passivation of HPGe has become crucial for achieving an extremely low energy threshold.In this study,first-principles simulations,passivation film preparation,and metal oxide semiconductor(MOS)capacitor characterization were combined to study surface passivation.Theoretical calculations of the energy band structure of the -H,-OH,and -NH_(2) passivation groups on the surface of Ge were performed,and the interface state density and potential with five different passivation groups with N/O atomic ratios were accurately analyzed to obtain a stable surface state.Based on the theoretical calculation results,the surface passivation layers of the Ge_(2)ON_(2) film were prepared via magnetron sputtering in accordance with the optimum atomic ratio structure.The microstructure,C-V,and I-V electrical properties of the layers,and the passivation effect of the Al/Ge_(2)ON_(2)/Ge MOS were characterized to test the interface state density.The mean interface state density obtained by the Terman method was 8.4×10^(11) cm^(-2) eV^(-1).The processing of germanium oxynitrogen passivation films is expected to be used in direct dark matter detection of the HPGe detector surface passivation technology to reduce the detector leakage currents.

Preliminary results of a Compton camera based on a single 3D position-sensitive CZT detector

A Compton camera prototype has been developed using a pixelated CZT detector with 4-by-4 pixels.Signals of the detector are read out by a VASTAT ASIC that is controlled by a self-developed DAQ board. The DAQ software is developed using LabVIEW, and the offline Compton imaging codes are written in C++. The prototype has been successfully calibrated, and its capabilities for source detection, spectroscopy, and Compton imaging have been demonstrated using a Cs-137 source.The angular resolution of the 662 keV line is 36° FWHM for the simple back-projection method and 9.6° FWHM for the MLEM reconstruction method. The system is ready to be extended to 11-by-11 pixels in the future, and a better imaging quality can be expected due to the better relative position resolution.

Sphingolipid metabolism affects the anticancer effect of cisplatin

Cisplatin,a DNA crosslinking agent,is widely used for the treatment of a variety of solid tumors.Numerous studies have demonstrated that sphingolipid metabolism,which acts as a target for cisplatin treatment,is a highly complex network that consists of sphingolipid signaling molecules and related catalytic enzymes.Ceramide(Cer),which is the central molecule of this network,has been established to induce apoptosis.However,another molecule,sphingosine-1-phosphate(S1P),exerts the opposite function,i.e.,serves as a regulator of pro-survival.Other sphingolipid molecules,including dihydroceramide,ceramide-1-phosphate,glucosylceramide(Glu Cer),and sphingosine(Sph),or sphingolipid catalytic enzymes such as Sph kinase(Sph K),Cer synthase(Cer S),and S1 P lyase,have also attracted considerable attention,particularly Cer,Glu Cer,Sph K,Cer S,and S1 P lyase,which have been implicated in cisplatin resistance.This review summarizes specific molecules involved in sphingolipid metabolism and related catalytic enzymes affecting the anticancer effect of cisplatin,particularly in relation to induction of apoptosis and drug resistance.

晶、胶体容量预负荷降低蛛网膜下隙阻滞剖宫产术中低血压发生率的Meta分析

目的蛛网膜下隙阻滞下行剖宫产术,麻醉前10~30 min或麻醉同时预先输注一定容量的晶、胶体溶液可有效减少术中低血压及恶心、呕吐的发生率,但对补充晶体液或胶体液、补液量以及补液时机的选择目前仍存争议。该文采用Meta分析的方法进行系统评价,为临床补液策略提供参考。方法选择PubMed、EMBASE、Cochrane Library及Research Gate数据库,检索所有相关随机对照试验。主要指标为术中出现低血压患者的数量;次要指标为术中出现恶心、呕吐症状患者的数量。结局各指标均采用随机效应模型,用比值比(O^R)及95%可信区间(95%CI)进行表示。结果蛛网膜下隙阻滞下行剖宫产术,与晶体液相比,同等量胶体预负荷可使术中低血压发生率降低[O^R=0.40(95%CI:0.27,0.59)];麻醉前10~30 min或麻醉同时快速输注500 ml胶体液可使术中低血压发生率降低[O^R=0.45(95%CI:0.31,0.66)],同等量晶、胶体容量预负荷在降低术中恶心、呕吐方面则无明显差异,均可使术中恶心、呕吐几率降低[O^R=0.72(95%CI:0.43,1.19)]。结论蛛网膜下隙阻滞下行剖宫产术,麻醉前10~30 min或麻醉同时预先快速输注500 ml胶体溶液可显著降低产妇术中低血压的发生率。

右美托咪定对免疫功能的影响及机制回顾

大多数镇静药对机体免疫功能有抑制作用,这与患者围手术期感染、肿瘤转移和复发等有关。由于ɑ2受体激动剂右美托咪定(DEX)对免疫系统的特殊影响,其用于围手术期、脓毒症及肿瘤等具有独特的临床优势。该文就近10年来DEX在动物实验和临床研究中对固有免疫、特异性免疫反应的研究进展作一综述,包括对巨噬细胞、树突状细胞、NK细胞、炎症因子、补体及抗体的影响。

Separation of hafnium from zirconium in hydrochloric acid solution with di(2-ethylhexyl)phosphoric acid by solvent extraction

The preparation of nuclear-grade zirconium and hafnium is very important for nuclear power. The separation of hafnium from zirconium in a hydrochloric acid solution by solvent extraction was investigated with di(2-ethylhexyl)phosphoric acid(D2 EHPA). The effects of hydrochloric acid concentration, extractant concentration,diluents, and temperature on the distribution coefficient of hafnium and zirconium were studied. The species extracted were ZrOA_2·2 HA and HfOA_2-2 HA. In this process, the separation factors varied with different diluents and followed the order octane > hexane > toluene > chloroform.A high separation factor value of 4.16 was obtained under the conditions of a solution containing 0.05 mol/L HCl and0.01 mol/L D2 EHPA for the separation of hafnium from zirconium. The extraction reaction was endothermic.

Searching for^(76)Ge neutrinoless double beta decay with the CDEX-1B experiment

We operated a p-type point contact high purity germanium(PPCGe)detector(CDEX-1B,1.008 kg)in the China Jinping Underground Laboratory(CJPL)for 500.3 days to search for neutrinoless double beta(0νββ)decay of^(76)Ge.A total of 504.3 kg⋅day effective exposure data was accumulated.The anti-coincidence and the multi/single-site event(MSE/SSE)discrimination methods were used to suppress the background in the energy region of interest(ROI,1989–2089 keV for this work)with a factor of 23.A background level of 0.33 counts/(keV⋅kg⋅yr)was realized.The lower limit on the half life of^(76)Ge 0νββdecay was constrained as T_(1/2)^(0ν)>1.0×10^(23)yr(90%C.L.),corresponding to the upper limits on the effective Majorana neutrino mass:<mββ><3.2–7.5 eV.

Morphological reconstruction of the Ediacaran macroalga Gesinella from South China

Macroalga Gesinella,a carbonaceous compression,is found in the upper part of Doushantuo Formation(Ediacaran)in the Yangtze Platform of South China.Morphologically,it is composed of a thallus(including an oval or oblong lamina and a short-rod-like stipe)and a holdfast(including a cone-shaped rhizome and many filamentous rhizoids).The cone-shaped rhizome connects with the stipe and the long rhizoids grew on the rhizome,meaning that the rhizome grew downwards and inserted into the sediment,while the rhizoids grew in the gaps between the sediment grains to anchor its body on the seafloor.On the lamina,branching and/or unbranching filaments are regularly distributed,so that the oval or oblong lamina can be interpreted as a sac-like body that has been compressed.The filaments on the lamina extend from the three-dimensionally preserved stipe,suggesting that the short-rod-like stipe may have been flexible to support the sac-like body in the water column.With tissue and organ differentiations,Gesinella can be regarded as a eukaryotic macroalga and a high-level metaphyte.Based on measurement and analysis of 108 specimens,the Ediacaran macroalga Gesinella from South China can be divided into three stages:juvenile stage(<3 mm maximum width)identified with difficulty,adult stage(3e10 mm maximum width)interpreted to have grown upwards for sunlight,and senescent stage(>10 mm maximum width)that grew sideways.

Glutamatergic Neurons in the Caudal Zona Incerta Regulate Parkinsonian Motor Symptoms in Mice

Parkinson’s disease(PD)is the second most common and fastest-growing neurodegenerative disorder.In recent years,it has been recognized that neurotransmitters other than dopamine and neuronal systems outside the basal ganglia are also related to PD pathogenesis.However,little is known about whether and how the caudal zona incerta(ZIc)regulates parkinsonian motor symptoms.Here,we showed that specific glutamatergic but not GABAergic ZIc^(VgluT2) neurons regulated these symptoms.ZIc^(VgluT2) neuronal activation induced time-locked parkinsonian motor symptoms.In mouse models of PD,the ZIc^(VgluT2) neurons were hyperactive and inhibition of their activity ameliorated the motor deficits.ZIc^(VgluT2) neurons monosynaptically projected to the substantia nigra pars reticulata.Incerta-nigral circuit activation induced parkinsonian motor symptoms.Together,our findings provide a direct link between the ZIc,its glutamatergic neurons,and parkinsonian motor symptoms for the first time,help to better understand the mechanisms of PD,and supply a new important potential therapeutic target for PD.

Synthesis of one-dimensional GaN nanorods by Tb intermediate layer with different thicknesses

GaN nanorods were synthesized by magnetron sputtering and ammonification system, and the thickness of Tb intermediate layer was changed to study the effect on GaN nanorods. The resultant was tested by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, transmission electron microscopy （TEM）, high-resolution transmission electron microscopy （HRTEM）, and photo- luminescence （PL） spectra. The results show that the thickness of Tb layer has an evident effect on the modality, quality, and luminescence properties of GaN nanorods. PL spectra at room temperature show a very strong emission peak at 368 nm and a weak emission peak at 387 nm, and the intensities of the peak for the produced samples reach the maximum when Tb layer is 20 nm. Finally, the optimal thickness of 20 nm of Tb intermediate layer for synthe- sizing GaN nanostructures is achieved.

Primary Hepatic Melanoma in a Child

To the Editor： A 12-year-old male patient was admitted to First Hospital of Lanzhou University with the complaint of right upper abdominal pain lasting for 2 years. He had no history ofhepatitis, vomiting, and weight loss during the past 2 years.

A new neutron detector based on ceramic THGEM and boron-coated meshes

Introduction Boron-coated micro-pattern gaseous detectors,such as gaseous electron multiplier(GEM),are widely studied as the neutron detectors.The existing solution to improve the neutron detection efficiency(NDE)is to coat the boron on the surfaces of the cascade GEM films.So the GEM films themselves will be affected by the complicated coating process and the boron layers,and the 10B material will be wasted once the GEM films are damaged.Since the neutron conversion and the electron multiplication regions are not separated,the final gains of different layer ionized electrons are very difficult to control and keep consistent.Materials and methods A new neutron detector based on the ceramic thick GEM(THGEM)was proposed.The boron-coated cathode and multilayer meshes were used as the neutron conversion region and separated from the electron multiplication region consisting of only one THGEM film.The sawtooth surface treatment and the double-sided readout method were applied to improve neutron conversion efficiency(NCE).The neutron conversion and the electron collection efficiencies were simulated and studied based on the new structure.The prototype detector was test by using a ^(252)Cf neutron source.Results The simulation results show that the cascade boron-coated meshes have good neutron conversion and electron collection efficiencies,and the double-sided readout and sawtooth structure can greatly increase the NCE.The neutron test results show that the detection efficiency of the double-sided readout is 1.6 times higher than that of the common single-sided readout.These indicate that the new detector has high neutron conversion and detection efficiencies and is promising for practical applications.

Development and study of an imaging detector based on high-position resolution THGEM

Introduction THickGaseous Electron Multiplier(THGEM)has many advantages while the moderate position resolution is regarded as the main inferiority comparing with the traditional GEM,so this limits the applications of THGEM,such as X-ray imaging and charge particle tracking.Materials and methods By improving the production techniques,THGEMs with smaller pitch and hole diameter can be made,i.e.,0.4 and 0.15 mm by mechanical drilling,and 0.3 and 0.1 mm by laser etching,respectively.Based on the new THGEMs,a two-dimensional imaging detector with 50×50mm sensitive area was developed for 0.1∼50 MeVlow-energy electrons detection and reaching better than 100μm position resolution(sigma).At the same time,a set of front-end electronics was developed based on homemade ASIC chips,i.e.,Charge Amplifier and Shaping Amplifier for GEM(CASAGEM),and applied successfully to the detector.Conclusion The X-ray and beam tests results indicate that both detector and Front End Electronics(FEE)worked well,and the position resolution achieved 74.9μm by using the charge center-of-gravity method.This indicates that the high-position resolution THGEM is promising for imaging and tracking application.

A scintillator detector for beam tuning of low-energy single electron accelerator

Purpose Nine scintillator detectors were developed for beam tuning of low-energy single electron accelerator instead of the picoammeter and Faraday cup,both of which will be insensitive to the weak-current beam lower than picoampere.Methods The detectors are based on plastic scintillator and photomultiplier tube(PMT)and the beam is 100 Hz pulsed electrons in the energy range of 0.1 to 50MeV.The beam flux was tuned from about 107 to quasi-single electron for each bunch according to the measurement results of these detectors installed along the beam pipe and after slits.In order to determine the number of electrons in a bunch,the gains of each PMT were finely calibrated,and the energy response of each detector was calibrated with 207Bi radioactive source.Moreover,the deposited energy in the plastic scintillator,the electron detection efficiency and light collection efficiency,as a function of electron incident energy,were also simulated in detail by Geant4.Results Nine detectors worked well at a gain of 0.6×10^(6) after installation in the beam pipe,and the number of electrons in a bunch could be measured at each detector position.The single electron peak was seen when the beam reached the final detector.Conclusion The commissioning result shows that the beam was tuned to quasi-single electron level successfully and the scintillator detector is an effective method to measure the weak-current beam lower than picoampere.