Gravitational radiation of angular—momentum from general covariant conservation law

The quadrupole angular-momentum radiation of gravity is obtained from the recently obtained covariant conservation law of angular-momentum.The result agrees with that derived from the Landau-Lifshitz energy-momentum pseudo-tensor.     

General covariant conservative angular momentum as internal charges

The usual approach to internal conservative charges is used to obtain the conservation laws of angular-momentum in both Einstein gravity and gravitational anyons.The results are in complete agreement with those of references.     

Bright γ-ray source with large orbital angular momentum from the laser near-critical-plasma interaction

We propose a new laser-plasma-based method to generate bright γ-rays carrying large orbital angular momentum by interacting a circularly polarized Laguerre–Gaussian laser pulse with a near-critical hydrogen plasma confined in an over-dense solid tube. In the first stage of the interaction, it is found via fully relativistic three-dimensional particle-in-cell simulations that high-energy helical electron beams with large orbital angular momentum are generated. In the second stage, this electron beam interacts with the laser pulse reflected from the plasma disc behind the solid tube, and helical γ beams are generated with the same topological structure as the electron beams. The results show that the electrons receive angular momentum from the drive laser, which can be further transferred to the γ photons during the interaction. The γ beam orbital angular momentum is strongly dependent on the laser topological charge l and laser intensity a0, which scales as ${L}_{\gamma }\propto {a}_{0}^{4}$. A short (duration of 5 fs) isolated helical γ beam with an angular momentum of −3.3 × 10⁻¹⁴ kg m² s⁻¹ is generated using the Laguerre–Gaussian laser pulse with l = 2. The peak brightness of the helical γ beam reaches 1.22 × 10²⁴ photons s⁻¹ mm⁻² mrad⁻² per 0.1% BW (at 10 MeV), and the laser-to-γ-ray angular momentum conversion rate is approximately 2.1%.     

Estimation of radiation hazard indices from natural radioactivity of some rocks

1 Introduction Naturally occurring radionuclides 226Ra, 232Th and 40K are widespread in the earth’s environment and they exist in various geological formation such as soil, rock, water and plants [1]. These radionuclides pose exposure risks externally due to their γ-ray emissions and internally due to radon and its progeny, which emit alpha particles. Even though these radionuclides are widely distributed, their concentrations have been found to depend on the local geological condition and …     

Total dose radiation effects of pressure sensors fabricated on Unibond－SOI materials

1 INTRODUCTIONSi1icon On Insulator (SOI) is used as an attIactive substrate fOr modern sub-Ancrometer integrated circults, especially fOr low t-oltage, low Jpower integrated cir-cuits. Moreover, SOI circuits are inherently toleranf, to ionizing irradiations and hightemperatures[1]. There has been an increasing tend,3ncy in recent years to aPply SOImaterials in the AncroelectromechanicaJ systems (MI:MS)t't']. ComPaxed with bulk si1-icon, SOI wafer has a bu-ried SiO2 layer. It c…     

Effects of radiation－induced oxide and interface charges on mobility degradation in MOSFETs

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Gyrokinetic theory of turbulent acceleration and momentum conservation in tokamak plasmas

Understanding the generation of intrinsic rotation in tokamak plasmas is crucial for future fusion reactors such as ITER. We proposed a new mechanism named turbulent acceleration for the origin of the intrinsic parallel rotation based on gyrokinetic theory. The turbulent acceleration acts as a local source or sink of parallel rotation, i.e., volume force, which is different from the divergence of residual stress, i.e., surface force. However, the order of magnitude of turbulent acceleration can be comparable to that of the divergence of residual stress for electrostatic ion temperature gradient(ITG) turbulence. A possible theoretical explanation for the experimental observation of electron cyclotron heating induced decrease of co-current rotation was also proposed via comparison between the turbulent acceleration driven by ITG turbulence and that driven by collisionless trapped electron mode turbulence. We also extended this theory to electromagnetic ITG turbulence and investigated the electromagnetic effects on intrinsic parallel rotation drive. Finally, we demonstrated that the presence of turbulent acceleration does not conflict with momentum conservation.     

Derivation of new mass,momentum, and energy conservation equations for two-phase flows

System codes are used to analyze nuclear reactor systems during steady state and transient operations. These codes are able to predict pressure drop, void fraction distributions and temperature distributions for various coolants, heated flow geometries, and heat configurations. They also include models for various two-phase flow regimes, but extreme flow conditions that involve significant phase change can tax the current code capabilities. Current system codes have mass, momentum, and energy conservation equations for two fields (liquid and vapor), resulting in a model with six conservation equations. Recent developments in limited applications of a few of these codes have added a separate droplet field from the continuous liquid. This is part of a trend toward the inclusion of more fields (and requisite conservation equations) in system codes. The representation of two phase flow phenomena is improved by increasing the number of fields. Conservation equations based on six fields (liquid, vapor, small bubble, large bubble, small droplet and large droplet) are derived in this work.     

聚合物辐射交联机理与其结构和运动多重性

研究和探讨了聚合物结构和运动的多重性以及对其辐射交联机制和规律性的影响,并对Charlesby-Pinner。方程及其不同修正式的适用性进行讨论。通过广角X射线衍射(WAXD)、差示扫描热法(DSC)、电子顺磁共振(ESR)等技术及凝胶和溶胶分析方法,对聚酰胺(PA)、聚氧化乙烯(PEO)、聚乙烯(PE)等不同聚合物的辐照效应与其结构关系进行了研究,对相关文献提供的结果做了详细讨论。在辐照初始低剂量区,由于端基效应(端联)和主链交联导致交联按非无规交联机制进行(交联度q0(D)=q0AXA q0BXB是剂量的函数),是导致聚合物辐射交联溶胶分数(s)与剂量(D)实验数据偏离Charlesby-Pinner经典无规交联关系的主要原因,当端基随剂量增大消耗至端基效应可以忽略时,聚合物非晶区主链单元的交联符合Charlesby-Pinner方程辐射无规交联机制假定,实验与理论一致(结晶相不参与反应);当剂量继续增大,因结晶表面(中间相)介入交联过程,反应又按非无规方式进行。     

正电子湮没辐射一维角关联实验装置的研制及性能

本文介绍正电子湮没辐射一维角关联实验装置的设计原理、主要技术性能和特点、调试方法及实验结果。本装置的角分辨率为0.45mrad。     

医疗保健产品辐照灭菌剂量设定方法的选择策略

随着核技术产业的日益发展,辐照灭菌已经成为了国际上医疗保健产品普遍采用的灭菌方式。但是按照国际标准ISO11137—2：2013的要求对医疗保健产品进行辐照灭菌剂量设定时,选择合适的灭菌剂量设定方法和实验过程仍存在一定的难度。本文将IS011137-2：2013标准中的灭菌剂量设定方法和实验过程按照5个关键性差异因素分成12个子类别,并制作成“灭菌剂量设定方法筛选表”。该筛选表作为一种灭菌剂量设定方法的选择策略,可以协助相关工作人员迅速准确地对一个新的医疗保健产品选择其合适的灭菌剂量设定方法,并制订相应的实验过程。     

A Monte Carlo investigation of secondary electron emission from solid targets: Spherical symmetry versus momentum conservation within the classical binary collision model

A Monte Carlo scheme is described where the secondary electron generation has been incorporated. The initial position of a secondary electron due to Fermi sea excitation is assumed to be where the inelastic collision took place, while the polar and azimuth angles of secondary electrons can be calculated in two different ways. The first one assumes a random direction of the secondary electrons, corresponding to the idea that slow secondary electrons should be generated with spherical symmetry. Such an approach violates momentum conservation. The second way of calculating the polar and azimuth angles of the secondary electrons takes into account the momentum conservation rules within the classical binary collision model. The aim of this paper is to compare the results of these two different approaches for the determination of the energy distribution of the secondary electrons emitted by solid targets.     

Studies of the radiation environment on the Mars surface using the Geant4 toolkit

The radiation environment on the surface of Mars is a potential threat for future manned exploration missions to this planet.In this study,a simple geometrical model was built for simulating the radiation environment on the Mars surface caused by galactic cosmic rays;the model was built and studied using the Geant4 toolkit.The simulation results were compared with the data reported by a radiation assessment detector （RAD）.The simulated spectra of neutrons,photons,protons,a particles,and particle...     

关于天基探测近地核爆瞬发辐射的思考

分析探讨了利用瞬发辐射天基探测核爆炸(包括空间核爆和近地核爆)的可行性,概略估算了近地核爆某些瞬发辐射粒子(含X,γ射线及中子等)自爆点垂直传播至同步探测卫星处的传输总衰减倍数A及相应的辐射厚度B和物理衰减因子Aph等.得出结果:利用γ射线与中子可探测高于10km的核爆;利用10keV X射线可探测高于40km的核爆炸,利用1keV X射线可探测高于80km的核爆炸.