Lifetime measurements of low-lying excited states in the semimagic (N=50) nucleus Rh95 have been performed by means of the fast-timing technique. The experiment was carried out using γ-ray detector arrays consisting of LaBr3(Ce) scintillators and germanium detectors integrated into the DESPEC experimental setup commissioned for the Facility for Antiproton and Ion Research () Phase-0, Darmstadt, Germany. The excited states in Rh95 were populated primarily via the β decays of Pd95 nuclei, produced in the projectile fragmentation of a 850 MeV/nucleon Xe124 beam impinging on a 4g/cm2Be9 target. The deduced electromagnetic E2 transition strengths for the γ-ray cascade within the multiplet structure depopulating from the isomeric Iπ=21/2+ state are found to exhibit strong deviations from predictions of standard shell model calculations which feature approximately conserved seniority symmetry. In particular, the observation of a strongly suppressed E2 strength for the 13/2+→9/2+ ground state transition cannot be explained by calculations employing standard interactions. This remarkable result may require revision of the nucleon-nucleon interactions employed in state-of-the-art theoretical model calculations, and might also point to the need for including three-body forces in the Hamiltonian. Published by the American Physical Society 2024

Electron-neutrino charged-current interactions with xenon nuclei were modeled in the nEXO neutrinoless double-beta decay detector (similar to 5 metric ton, 90% Xe-136, 10% Xe-134) to evaluate its sensitivity to supernova neutrinos. Predictions for event rates and detectable signatures were modeled using the Model of Argon Reaction Low Energy Yields (MARLEY) event generator. We find good agreement between MARLEY's predictions and existing theoretical calculations of the inclusive cross sections at supernova neutrino energies. The interactions modeled by MARLEY were simulated within the nEXO simulation framework and were run through an example reconstruction algorithm to determine the detector's efficiency for reconstructing these events. The simulated data, incorporating the detector response, were used to study the ability of nEXO to reconstruct the incident electron-neutrino spectrum and these results were extended to a larger xenon detector of the same isotope enrichment. We estimate that nEXO will be able to observe electron-neutrino interactions with xenon from supernovae as far as 5-8 kpc from Earth, while the ability to reconstruct incident electron-neutrino spectrum parameters from observed interactions in nEXO is limited to closer supernovae.

Direct lifetime measurements via gamma -gamma coincidences using a fast timing detector array consisting of LaBr3(Ce) scintillators has been applied to determine the lifetime of low-lying states in the semimagic (N = 50) nucleus Ru-94. The experiment was carried out as the first in a series of "FAIR-0" experiments with the DESPEC experimental setup at the Facility for Antiproton and Ion Research (FAIR). Excited states in Ru-94 were populated primarily via the beta-delayed proton emission of Pd-95 nuclei, produced in the projectile fragmentation of an 850 MeV/nucleon Xe-124 beam impinging on a 4 g/cm(2) Be-9 target. While the deduced E2 strength for the 2(+) -> 0(+) transition in the yrast cascade follows the expected behavior for conserved seniority symmetry, the intermediate 4(+) -> 2(+) transition exhibits a drastic enhancement of transition strength in comparison with pure-seniority model predictions as well as standard shell model predictions in the f pg proton hole space with respect to doubly magic Sn-100. The anomalous behavior is ascribed to a subtle interference between the wave function of the lowest seniority v = 2, I-pi = 4(+) state and that of a close-lying v = 4 state that exhibits partial dynamic symmetry. In addition, the observed strongly prohibitive 6(+) -> 4(+) transition can be attributed to the same mechanism but with a destructive interference. It is noted that such effects may provide stringent tests of the nucleon-nucleon interactions employed in state-of-the-art theoretical model calculations.

AbstractLiquid xenon time projection chambers are promising detectors to search for neutrinoless double beta decay (0$$\nu \beta \beta $$νββ), due to their response uniformity, monolithic sensitive volume, scalability to large target masses, and suitability for extremely low background operations. The nEXO collaboration has designed a tonne-scale time projection chamber that aims to search for 0$$\nu \beta \beta $$νββof$$^{136}$$136Xe with projected half-life sensitivity of$$1.35\times 10^{28}$$1.35×1028 yr. To reach this sensitivity, the design goal for nEXO is$$\le $$≤1% energy resolution at the decayQ-value ($$2458.07\pm 0.31$$2458.07±0.31 keV). Reaching this resolution requires the efficient collection of both the ionization and scintillation produced in the detector. The nEXO design employs Silicon Photo-Multipliers (SiPMs) to detect the vacuum ultra-violet, 175 nm scintillation light of liquid xenon. This paper reports on the characterization of the newest vacuum ultra-violet sensitive Fondazione Bruno Kessler VUVHD3 SiPMs specifically designed for nEXO, as well as new measurements on new test samples of previously characterised Hamamatsu VUV4 Multi Pixel Photon Counters (MPPCs). Various SiPM and MPPC parameters, such as dark noise, gain, direct crosstalk, correlated avalanches and photon detection efficiency were measured as a function of the applied over voltage and wavelength at liquid xenon temperature (163 K). The results from this study are used to provide updated estimates of the achievable energy resolution at the decayQ-value for the nEXO design.

Mass measurements of the $^{69}$As, $^{70,71}$Se and $^{71}$Br isotopes, produced via fragmentation of a $^{124}$Xe primary beam at the FRS at GSI, have been performed with the multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) of the FRS Ion Catcher with an unprecedented mass resolving power of almost 1,000,000. For the $^{69}$As isotope, this is the first direct mass measurement. A mass uncertainty of 22 keV was achieved with only 10 events. For the $^{70}$Se isotope, a mass uncertainty of 2.6 keV was obtained, corresponding to a relative accuracy of $\delta$m/m = 4.0$\times 10^{-8}$, with less than 500 events. The masses of the $^{71}$Se and $^{71}$Br isotopes were measured with an uncertainty of 23 and 16 keV, respectively. Our results for the $^{70,71}$Se and $^{71}$Br isotopes agree with the 2016 Atomic Mass Evaluation, and our result for the $^{69}$As isotope resolves the discrepancy between previous indirect measurements. We measured also the mass of $^{14}$N$^{15}$N$^{40}$Ar (A=69) with a relative accuracy of $\delta$m/m = 1.7$\times 10^{-8}$, the highest yet achieved with a MR-TOF-MS. Our results show that the measured restrengthening of the proton-neutron interaction ($\delta$V$_{pn}$) for odd-odd nuclei at the N=Z line above Z=29 (recently extended to Z=37) is hardly evident at N-Z=2, and not evident at N-Z=4. Nevertheless, detailed structure of $\delta$V$_{pn}$ along the N-Z=2 and N-Z=4 lines, confirmed by our mass measurements, may provide a hint regarding the ongoing $\approx$500 keV discrepancy in the mass value of the $^{70}$Br isotope, which prevents including it in the world average of ${Ft}$-value for superallowed 0$^+\rightarrow$ 0$^+$ $\beta$ decays. The reported work sets the stage for mass measurements with the FRS Ion Catcher of nuclei at and beyond the N=Z line in the same region of the nuclear chart, including the $^{70}$Br isotope.

Accurate measurements of panoramic/dual-surface kinematic fields are essential to elastoplastic mechanics for the determination of true stress-strain curves, through-thickness strain and the identification of 3D anisotropic parameters. Recently, a novel mirror-assisted multi-view digital image correlation (DIC) method that uses only a two-camera stereo-DIC system and two auxiliary planar mirrors was proposed. It has been convincingly demonstrated to be a cost-efficient and effective technique for measuring 360-deg panoramic/dual-surface kinematic fields. Nevertheless, in this method, the mirrors need to be partly decorated with speckle patterns and the latter clearly captured by the cameras to estimate the reflection transformation of both mirrors. Capturing the speckle patterns on the two mirrors occupies a part of the precious spatial resolution of the cameras, considerably reducing the effective spatial resolution left for the DIC measurement. In this work, an alternative method for estimating the reflection transformation is proposed to improve the spatial resolution of the mirror-assisted multi-view DIC. This method estimates the reflection transformation of the two mirrors by adjusting the mirrors to three or more diverse poses, thus eliminating the need of speckling the mirrors. A set of real tests were carried out, and the results well demonstrated the accuracy and effectiveness of the proposed method.

针对鄂尔多斯临兴神府区块低温储层开展压裂液优化研究,通过大量岩心实验和测井数据认识区块储层特性,开展破胶剂体系优化实验,利用低温催化剂实现低温下快速破胶,从而实现快速返排,减少压裂液与地层的接触时间.同时,利用30～80℃高活性生物酶破胶剂,高效降低破胶液残渣含量,实现残胶的彻底清理,从而保证裂缝的导流能力.各种破胶剂加量的设计考虑压裂液注入对地层温度的影响,进行阶梯化设计,实现较短时间破胶.针对储层物性特征对稠化剂、黏土稳定剂和助排剂等进行优化,得到一套经济有效的压裂液体系.该体系在本区块30多口生产井约100层应用,统计现场测试基液黏度为18～27 mPa·s,交联时间35～55 s.压裂施工结束关井1 h后,开井放喷,返排液黏度均低于5 mPa·s,已完全破胶.初期产量和累计产量均明显好于采用压裂液体系未经过针对性设计的单一氧化性破胶剂,且多口井实现高产,证明优化后的压裂液体系在该区块具有非常好的适用性.

为了研究含铝炸药的反应过程,采用激光烧蚀手段激发了RDX基含铝炸药粉末的快速反应,并对反应过程中的发射光谱分布进行了实时监测,并基于AlO分子光谱对反应区域的瞬态温度进行了计算.结果表明,含铝炸药在前期和后期的光谱分布和反应行为存在明显区别:前期主要为RDX和空气在激光烧蚀下形成的等离子冷却和耗散过程,O/H/N元素的发射光谱在这一阶段占主导地位,其谱线高度呈指数型衰减;后期以铝的氧化反应为主,该反应具有一定自持性,对应的反应中间产物AlO分子的光谱具有持续久、非单调变化的典型特征.温度变化趋势与整个反应发展趋势紧密相关,反应较剧烈的初期温度较高,并随着反应的持续变弱而变低.

The purpose of the study is to evaluate the feasibility of blood oxygenation level-dependent MRI (BOLD-MRI) to early detect the femoral head osteonecrosis (FHON). One hundred twelve patients were recruited who had received steroid treatment. The normal control group included 10 volunteers with 20 hips. MRI examinations were performed in all patients following up at 1, 4 to 5, 7 to 8, and 12 to 13 months after steroid therapy. With the section cross as the biggest lesion in coronal images, we set 6 regions of interest (ROIs) per section to analyze the morphological performance of routine MRI sequences and the differences of R2* values and their dynamic changes of BOLD-MRI between the control and the FHON group. A total of 15 hip joints were diagnosed with FHON. Seven right hips and 8 left hips were affected. In the first and second MRI examinations, the area of the lesion for both conventional MRI and BOLD-MRI R2* mapping was difficult to distinguish the lesion border. However, at the third and the fourth MRI examinations, some of the affected regions for R2* mapping were larger than those in conventional sequences for the same patient. BOLD-MRI has some significant advantages in early detecting FHON over conventional MRI techniques and it can be feasible noninvasive tool for detecting and evaluating FHON after steroid therapy.

High pressure Raman experiment was performed to compare RDX and HMX crystals. Ab initio calculations using B3LYP Density Functional Theory method with Sadlej's medium-sized polarized basis set (SadlejpVTZ) were carried out for Caae RDX and 1,5-diaxial-3,7-diequatorial chair HMX molecules. Our calculations and measured Raman vibrational spectra reveal both molecules have similarities on bonding and vibrational properties at ambient pressure. However, high pressure responses for both molecules aren't the same. For RDX, at pressure near 4 GPa, a number of changes become apparent in the Raman spectra, such as modes splitting, intensity modification, and discontinuity of pressure-dependence of frequency shifts, which are consistent with previous experiment and believed to associate with alpha-gamma phase transition. For HMX, only slight conformational deformation involving NO2 group was observed, and was considered as an onset of beta-epsilon phase transition. It is proposed that the markedly different behavior under high pressure for these two molecules results from different molecular packing in unit cell. (c) 2016 Elsevier B.V. All rights reserved.

Background: There are four common methods to prepare radioactive aerosol samples for the purpose of gamma-spectroscopy involving an HPGe detector: ashing method, compressing method, holing method, and folding method. However, their counting characteristics have never been studied and compared.Purpose: This study aims to provide a comprehensive evaluation of these four sample preparation methods.Methods: An HPGe gamma spectrometer was used in the study to evaluate and confirm the reliability of these four radioactive aerosol sample preparation methods. Monte Carlo simulations were used to calculate the gamma-spectroscopic counting efficiency. Results: The four preparation methods were found to be generally reliable, with assessed activity differing less than 5%. The ashing method was found to yield the highest counting efficiency, followed by compressing method, holing method, and folding method. For the 260mm×210mm and 570mm×470mm sized filter, the variation range of gamma detection efficiency was found to be 55% and 120%.Conclusion: The analyses of these sample preparation methods provide useful suggestions on the suitability and conditions, thus offering a useful reference on how to choose, prepare and count radioactive aerosols samples.

Previous studies have explored the effect of granulocyte colony stimulating factor (G-CSF) administration on the outcome of assisted reproductive technology (ART), and came into controversial conclusions. The present meta-analysis aims to assess whether G-CSF administration has beneficial effect on the outcome after ART.

Background The present study aims to compare which one has a better obstetric and perinatal outcome in singleton pregnancy, frozen embryo transfer (FET) or. in vitro fertilization treatment/intracytoplasmic sperm injection (IVF/ICSI)? Methods MEDLINE, Google Scholar and the Cochrane Library were searched for the obstetric and perinatal outcomes in singleton pregnancy after assisted reproductive technology (ART) from inception until July 2016. Clinical trials, which compared obstetric/perinatal outcomes in singleton pregnancy after FET and IVF/ICSI-ET, were included. The primary outcome was low birth weight, preterm birth, perinatal mortality, still birth, and cesarean section. Results Thirteen cohort studies with 126,911 women were included, of which 12, 11, 6, 6, 5 studies were used to analyze low birth weight, preterm birth, perinatal mortality, still birth, and cesarean section, respectively. IVF/ICSI is associated with a high risk of preterm birth (OR = 1.14, 95 % CI: 1.02, 1.28) and low birth rate (OR = 1.48, 95 % CI: 1.37, 1.60). There was no significant difference in the risk of the still birth (OR = 1.01, 95 % CI: 0.76, 1.35) and perinatal mortality (OR = 1.11, 95 % CI: 0.85, 1.46) between FET and IVF/ICSI. Singleton pregnancy after FET was associated with higher cesarean section rate compared with IVF/ICSI (OR = 0.85, 95 % CI: 0.80, 0.91). Conclusions Singleton pregnancy after FET seems to have a better perinatal outcome compared with that after IVF/ICSI. Further randomized controlled trials which adjust for a variety of meaningful confounders are needed in order to draw sound conclusions.

The craft of single grade CuFC adsorption+ microfiltration was used to treat the simulative wastewater containing 137Cs .The affects of the initial activity concentration of 137 Cs ,the adsorption time ,pH ,competing ions and the dosage of CuFC on decontamination fator(DF) were studied .The results indicate that when the adsorption time is 90 min ,pH is 7 ,the dosage of CuFC is 80 mg/L ,and add no competing ions ,DF reach 2.06 × 104 ,1.62 × 104 and 9.36 × 101 respectively for simulative wastewater made up of pure water (C0 =4.24 × 105 Bq/L) ,surface water(C0 =2.84 × 105 Bq/L ) and seawate(C0 =2.84 × 105 Bq/L ) .It indi‐cates that the craft of CuFC adsorption‐microfiltration is a high‐efficiency craft to treat wastewater containing 137Cs ,and has considerable application prospect .

A nanosecond time-resolved shadowgraphy is performed to observe a laser-induced breakdown in nitromethane. The digital delays are introduced between a pump beam and an illumination light to achieve a measuring range from 40 ns to 100 ms, which enable us to study the shock wave propagation, bubble dynamics, and other process of the laser-induced breakdown. Compared with distilled water, there are two obvious differences observed in nitromethane: (1) the production of a non-evaporative gas at the final stage, and (2) an absence of the secondary shock wave after the first collapse of the bubble. We also calculated the bubble energy in nitromethane and distilled water under a different incident energy. The results indicate that the bubble energy in nitromethane is more than twice as large as that in water. It is suggested that chemical reactions contribute to the releasing of energy.

A tunnel is an underground horizontal passage that is constructed to provide services such as transportation, storage places, water, wastewater lines, and the like. Since the tunneling depth in most of the large cities is shallow and lies within the soft ground zone, it is clear that there is a need for a complete understanding of tunnel behavior in soft ground. Underground facilities constructed in soft soils and weak rocks are more vulnerable to earthquake loads when compared to those that are constructed in intact rock. Tunnels experience large stresses, and severe damages may occur when they are subjected to dynamic loading. Hence, proper consideration of an earthquake event in the analysis of tunnels is very important to ensure that these tunnels are safe and stable. In this study, a fully non-linear plane strain analysis was performed using the finite element program, PLAXIS2D AE.02 in order to examine the influence of the dynamic input motion parameters on the behavior of a tunnel during an earthquake. A numerical model is validated by centrifuge test results against tunnel-induced surface settlement in a static condition. The same numerical model is extended to carry out dynamic analyses by using input motions of different amplitudes and frequencies. A parametric study shows that the dynamic axial force and bending moment in a tunnel lining increases with an increase in the magnitude of the earthquake. The results show that the maximum and residual dynamic earth pressure around the tunnel lining is enormously affected by the magnitude and duration of the maximum base acceleration.

Cutting explosive single crystals and obtaining oriented crystal wafers (particularly crystal surfaces) are significant to research microscopic changes in highly explosive crystal wafers in various mechanical response mechanisms. Crystals have been cultivated to investigate the basic characteristics of explosives. In this study, the attachment energy (AE) model was employed to predict 1,3,5,7-tetranitro-1,3, 5,7-tetraazacy-clooct ane (HMX) crystal morphology. The gradient cooling method was used to cultivate HMX crystal in acetonitrile solution. The face of the HMX crystal was defined via X-ray diffraction pattern analysis. Simulation result shows that the predicted morphology of the HMX crystal in acetonitrile solution is dominated by the (0 1 1), (1 1 −1), and (1 0 0) faces calculated via solvent-affected AE using the AE model. The predicted HMX morphology is reasonably consistent with the observed experimental result. The mechanism of solvent effects on the structure of crystal surfaces during the process of cultivating crystals was explained by discussing binding energy and adsorption sites. Molecular modeling (MD) simulation was employed to demonstrate the interaction on the solvent surface. The MD method provides guidance to cultivate HMX crystals with various crystal faces in different solvents and under varying experimental conditions.

据目前的统计资料表明,我国煤层气资源总量约为36.8×1012 m3,可采储量为10.9×1012 m3,开采潜力巨大.以沁水盆地3#煤层为例,对煤层割理特征、孔缝填充物赋存状态及类型、酸液对煤岩孔缝中的充填物溶蚀情况进行了研究.得出3#煤层主要发育两组割理系统,裂隙多为方解石充填,可通过有机酸酸化解除部分填充物对煤岩孔缝的堵塞.根据煤岩可酸化的性能特征研究出了适用于煤层气井的潜在酸压裂液.实验表明:压裂液pH在1h后才趋于稳定,3h时pH可降至最低(＜1);对煤粉的平均溶蚀率为3.48％,且具有较好的缓速性能;抗剪切性能好,2h时表观黏度仍高于35 mPa·s;破胶液对煤心的渗透率伤害率＜10％.现场应用5口井,施工曲线表明,该潜在酸压裂液能降施工压力,提高施工成功率;微地震监测结果表明,该潜在酸压裂液能够实现储层深度改造.