Internal Conversion Coefficients for Observed Low-Energy Gamma Transitions

Physics of Atomic Nuclei - The total internal conversion coefficients for experimentally observed low-energy ( $$E_{gamma}lesssim 10$$ keV) gamma transitions are calculated. The resulting values...     

Mesons in the Low-Energy Limit of QCDh

Quark-antiquark bound states are described within the Bethe-Salpeter approach for a class of quark models with instantaneous 4-quark interaction. Thereby decompositions of the Bethe-Salpeter vertex and wave functions according to their Lorentz structures and the particle content are used. Normalization conditions for the bound state functions are given. As an application of the general scheme, we determine the mass spectrum of low-lying mesons without expanding in energy. This calculation is performed for a special Nambu-Jona-Lasinio model which follows from the so-called QCD for hadrons, QCD_h, by a localization of the potential. Furthermore the pion and kaon decay constants are determined. We receive good agreement with the experimental data.     

X-Ray-Driven Gamma Emission

X-ray-driven gamma emission describes processes that may release nuclear energy in a ‘clean’ way, as bursts of incoherent or coherent gamma rays without the production of radioactive by-products. Over the past decade, studies in this area, as a part of the larger field of quantum nucleonics, have gained tremendous momentum. Since 1987 it has been established that photons could trigger gamma emission from a long-lived metastable nuclear excited state of one nuclide and it appears likely that triggering in other isotopes will be demonstrated conclusively in the near future. With these experimental results have come new proposals for the creation of collective and avalanche-like incoherent gamma-ray bursts and even for the ultimate light source, a gamma-ray laser. Obviously, many applications would benefit from controlled bursts of gamma radiation, whether coherent or not. This paper reviews the experimental results and concepts for the production of gamma rays, driven by externally produced X-rays. This revised version was published online in July 2006 with corrections to the Cover Date.     

Review of Induced Gamma Emission and Gamma-Ray Laser Research

Induced gamma emission with the potential for substantial energy gain is an exciting area of research. This paper reviews related work done internationally, including some that has potential for a gamma-ray laser. This revised version was published online in August 2006 with corrections to the Cover Date.     

Initial Search for Triggered Gamma Emission from 178Hfm2 Using the YSU Miniball Array

Experiments with the long-lived, high-K isomer ¹⁷⁸Hf^m2 have been recognized as intriguing tests of multi-quasiparticle state structures and their interactions with external radiation. A triggered release of the energy stored by this isomer, 2.5 MeV per nucleus or 1.2 GJ/gram, in the form of a gamma-ray burst might prove valuable for numerous applications. The observation of “accelerated” decay of ¹⁷⁸Hf^m2 during irradiation by 90-keV bremsstrahlung has already been reported, but with poor statistical accuracy due to the experimental approach. That approach employed single Ge detectors to seek increases in the areas of peaks at energies corresponding to transitions in the spontaneous decay of the isomer. The need for better quality data to confirm those results has motivated the development of improved detection concepts. One such concept was utilized here to perform an initial search for low-energy (<20 keV) triggered gamma emission from ¹⁷⁸Hf^m2 using the YSU miniball detector array. This revised version was published online in August 2006 with corrections to the Cover Date.     

Stimulated Emission of Gamma Photon from Ultrashort Pulse Intense Laser-Solid-Target Interaction

The efficient production of energetic γ photons is a significant physical process in the relativistic ultrashortpulse laser-plasma inducing photonuclear action. Based on the interaction of laser-solid-target, an analytical theory onstimulated γ photon emission from a hot electron firing the target-nucleus is developed by a relativistic full quantummethod. The emitting power or probability of γ photon in arbitrary space direction can be calculated for laser irradiatingsolid-target normally. It is valid only if the scatter-centre is immovable or its motion can be neglected compared withthat of the scattered electrons.     

Using Low-Energy Electrons for the Radiation Treatment of Chilled Trout

Physics of Particles and Nuclei Letters - Chilled minced trout has been treated by 1-MeV electron-beam irradiation using the UELR-1-25-T-001 industrial electron accelerator. The results of the...     

Quantum Flows as Markovian Limit of Emission,Absorption and Scattering Interactions

We consider a Markovian approximation, of weak coupling type, to an open system perturbation involving emission, absorption and scattering by reservoir quanta. The result is the general form for a quantum stochastic flow driven by creation, annihilation and gauge processes. A weak matrix limit is established for the convergence of the interaction-picture unitary to a unitary, adapted quantum stochastic process and of the Heisenberg dynamics to the corresponding quantum stochastic flow: the convergence strategy is similar to the quantum functional central limits introduced by Accardi, Frigerio and Lu [1]. The principal terms in the Dyson series expansions are identified and re-summed after the limit to obtain explicit quantum stochastic differential equations with renormalized coefficients. An extension of the Pulé inequalities [2] allows uniform estimates for the Dyson series expansion for both the unitary operator and the Heisenberg evolution to be obtained.     

On the Parametrization of Low-Energy Parity-Violating Observables

The parity-violating (PV) two-nucleon interaction, unlike the parity-conserving one, is still poorly constrained. Recently such study in few-body systems has attracted quite some attention, as experiments become more feasible and theoretical calculations can be done reliably. It is found that using the so-called Danilov parameters, which are the zero-energy S–P transition amplitudes, yield a model independent way to parametrize low-energy PV observables. This provides not only a common interface through which calculations using different frameworks can communicate, but also helps to distinguish for which observables the contributions from higher partial waves can no longer be ignored.     

利用羊八井广延大气簇射阵列探测来自壳型超新星遗迹G40.5-0.5的TeV Gamma射线发射

利用羊八井广延大气簇射阵列从2000年10月到2001年9月的数据,对壳型超新星 遗迹G40.5-0.5可能的TeV gamma射线发射进行了探测. 用对扩展源的二维分析方法发现一个最高超出为4.4σ的天区,EGRET不明源GeV J1907+0557非常接近 这一最高超出天区的中心.     

Low-Energy Universality in Three-Body Models

 We study the low-energy universality observed in three-body models through a scale-independent approach. From the already estimated infinite number of three-body excited energy states, which happen in the limit when the energy of the subsystem goes to zero, we are able to identify the lower energies of the helium trimers as possible examples of Thomas-Efimov states. By considering this example, we illustrate the usefulness of a scaling function, which we have defined. The approach is applied to bosonic systems of three identical particles, and also to the case where two kinds of particles are present. Received June 30, 1999; revised July 27, 1999; accepted for publication August 29, 1999     

Search for a TeV Gamma Rays Emission from the Shell-like SNP G40.5-0.5 Using the Yangbajing Extend Air Shower Array

Using observation data of the Yangbajing extensive air shower array from October 2000 to September 2001, the TeV gamma rays from the shell-like SNR G40.5-0.5 direction were detected. A region with the highest excess of 4.4σ was found using two dimensional analysis method.The position of EGRET unidentified source GeV J1907+0557 is near the centrer of the region.     

Experimental Limit on the Probability of Neutral Pion Emission in Neutron-Induced Fission of 235U Nuclei

Results of an experiment on the search for the emission of ⁰ mesons in neutron-induced fission of ²³⁵U nuclei based on the detection in coincidence of two -quanta from the ⁰-meson decay performed with the nuclear reactor developed at the Scientific-Research Nuclear Physics Institute at Tomsk Polytechnic University are described. The experimental setup comprised two erenkov spectrometers of total absorption for the detection and measurement of -quantum energy placed in two coaxial horizontal channels of the nuclear reactor. Water filters placed in the channels were used to protect the detectors from -, -, and neutron fluxes. To reject the cosmic radiation, scintillation counters of large area, operating in anticoincidence mode, were placed above each spectrometer. The experimentally measured limitation on the probability of neutral pion emission in neutron-induced fission of nuclei was established 4.1·10^–11 with a 90% confidence level. The energy spectrum of -quanta from the active reactor zone was measured in the range 32–65 MeV. The parameters of the spectrum deviated from the results of theoretical calculations and from the experiment performed with the nuclear pulse reactor developed at the Joint Institute for Nuclear Research (Dubna).     

Low-Energy Proton-Deuteron Scattering in Configuration Space

 A new method for solving the configuration-space Faddeev equations for elastic p-d scattering below the deuteron-breakup threshold is described. Numerical solutions that demonstrate the convergence and accuracy of the method are given. The number of channels and the value of the matching radius required to obtain an accurate solution are also investigated. These calculations demonstrate that this method can efficiently solve the large matrix equations required for the three-body scattering problem. Received April 23, 2001; accepted for publication June 7, 2001     

String-Loop Effect in Low-Energy Effective Theory

In this short article we are going to obtain the equations of motion from the low-energy effective action in the string cosmology. In the first time we consider the string-loop effect in the dilaton gravity and obtain the equations of motion, and obtain solution of them under some assumption for the specific potential.     

低能反质子的核散射与Glauber理论

运用Glauber多次散射理论,分析低能量反质子与⁴He核的弹性散射微分截面的实验结果.看到反质子能量低到19.6MeV时,多次碰撞的特征仍然是主要的.用光学模型的计算和比较,也得到相同的结论.     

基于移动agent的WSN低能耗数据融合策略设计

为了解决无线传感器网络中LEACH协议中传感器节点需要耗费大量能量,导致节点过早死亡,在LEACH协议的基础上,将移动agent引入到数据融合策略中,提出了一种基于移动agent和LEACH协议的数据融合策略;首先,改进簇头选举机制,考虑剩余能量和与基站的距离等因素;其次,为了避免访问冗余节点而耗费能量,确定了访问节点集合,并通过改进的遗传算法来获得访问节点序列;最后,通过仿真实验并与LEACH协议、AF-LEACH协议进行比较,文中方法节点死亡时间在470s才出现,延迟了节点死亡时间,从而延长了网络的生命周期。