Deriving Energy-Gap of Some Nonlinear Hamiltonians by Invariant Eigen-operator Method

By virtue of the invariant eigen-operator method we search for the invariant eigen-operators for some Hamiltonians describing nonlinear processes in particle physics. In this way the energy-gap of the Hamiltonians can be naturally obtained. The characteristic polynomial theory has been fully employed in our derivation.     

Signals of the littlest Higgs model with T-parity at eγ and ep collisions

The littlest Higgs model with T-parity predicts the existence of the neutral, weakly interacting, new gauge boson B_H, which can be seen as an attractive dark matter candidate. We study production of the new gauge boson B_H via eγ and ep collisions. We find that B_H can be abundantly produced via the subprocesses e^－γ→L^－B_H and γq→B_HQ, which might give rise to characteristic signals. Some discussions about the SM backgrounds for this kind of signals are also given.     

Neutrino energy loss by electron capture in magnetic field at the crusts of neutron stars

Based on the p-f shell model, the effect of strong magnetic field on neutrino energy loss rates by electron capture is investigated. The calculations show that the magnetic field has only a slight effect on the neutrino energy loss rates in the range of 10⁸—10¹³G on the surfaces of most neutron stars. But for some magnetars, the range of the magnetic field is 10¹³—10¹⁸G, and the neutrino energy loss rates are greatly reduced, even by more than four orders of magnitude due to the strong magnetic field.     

Digital prototype of LLRF system for SSRF

This paper describes a field programming gate array (FPGA) based low level radio frequency (LLRF) prototype for the SSRF storage ring RF system. This prototype includes the local oscillator (LO), analog front end, digital front end, RF out, clock distributing, digital signal processing and communication functions. All feedback algorithms are performed in FPGA. The long term of the test prototype with high power shows that the variations of the RF amplitude and the phase in the accelerating cavity are less than 1% and 1° respectively, and the variation of the cavity resonance frequency is controlled within ±10 Hz.     

A new tuning procedure for the DTL RF field pattern

The DTL tank is a multi-cell cavity. In a fabricated tank,the measured average axial field E₀ for each cell may obviously deviate from the designed value. It is generally thought the deviation is due to the errors in fabrication and assembly. But it is not always true. In this paper, it is shown that the deviation may already exist before fabrication in some cases. It is partly due to the imperfection of the current design procedures. A new design method is introduced to reduce the deviation in the design stage.     

15—20mA负氢离子源的设计与加工

离子源是强流质子回旋加速器的核心设备之一, 它的性能指标对最终束流大小和质量都有重大影响. 文章介绍了一种运用于强流质子回旋加速器上的多峰场负氢离子源的设计与加工情况, 该离子源主要是通过深入研究高密度等离子体产生技术、长寿命大直流灯丝电子发射技术、磁约束技术、虚拟过虑技术、残留气体与电子剥离的控制技术, 以及离子引出技术等, 在中国原子能科学研究院原有10mA离子源基础上建立负氢离子源, 实验研究低能、强流束的实验匹配与调试技术, 将平均引出束流提高到15—20mA.     

微型数据采集器及其在加速器周围辐射场实时监测中的应用

各种类型加速器周围的辐射场变化是很复杂的, 只有对其进行连续的实时监测才能准确地掌握全面资料. 以往的数据采集系统用的是模拟信号长距离传输方式, 采集器体积较大, 存储技术上也显落后, 已不能适应当今的需求. 为辐射场实时监测研制的微型数据采集器采用了先进的设计理念, 具有体积小、通讯能力强、数据存储量大且断电数据不丢失的特点, 可运行于局域网环境. 它既可利用局域网远距离向控制计算机传递数据, 也可用便携式PC通过串口就近读取数据. 所以它不但适于固定场所的连续监测, 也可灵活地用于临时测量场所. 介绍了它的主要性能和在各类型加速器周围所做测量的结果.     

The dynamical mixing of light and pseudoscalar fields

We solve the general problem of mixing of electromagnetic and scalar or pseudoscalar fields coupled by axion-type interactions L _int = g _ϕ ϕε _μναβ F ^μν F ^αβ . The problem depends on several dimensionful scales, including the magnitude and direction of background magnetic field, the pseudoscalar mass, plasma frequency, propagation frequency, wave number, and finally the pseudoscalar coupling. We apply the results to the first consistent calculations of the mixing of light propagating in a background magnetic field of varying directions, which show a great variety of fascinating resonant and polarization effects.      

The effect of magnetic field heat treatment on magnetostriction of Terfenol-D 2-2 composites

Based on the analysis of the magnetostriction for Terfenol-D composites, Terfenol-D 2-2 magnetostrictive composites have been prepared with laminations perpendicular to [1 1 2] axes. Then one of the samples was annealed in the vacuum at 423 K for 15 min at the magnetic field of 240 kA/m, which is along the direction of laminations and vertical to the [1 1 2] axes of the specimen. The static magnetostriction λ and dynamic magnetostrictive coefficient d₃₃ of samples were measured under the compressive stress of 0, 2, 4, 6 and 8 MPa. Effects of the compressive stress and the magnetic field heat treatment on the magnetostriction λ have been investigated. It is found that the magnetostriction of 2-2 composites can be improved under the compressive stress when the magnetic field is larger than 20 kA/m. The magnetostriction of 2-2 composites with the magnetic field heat treatment increases under compressive stress, and it can reach 1390×10⁻⁶ at the magnetic field of 200 kA/m and under the compressive stress of 4 MPa, much larger than the value of 860×10⁻⁶ without the magnetic field heat treatment. The highest magnetostriction of the 2-2 composite with the magnetic field heat treatment can reach 1530×10⁻⁶. The dynamic magnetostrictive coefficient d₃₃ of 2-2 composites with the magnetic field heat treatment have been improved, compared with that without magnetic field heat treatment. The maximum value of d₃₃ of the sample with magnetic field heat treatment is 71% larger than that without magnetic field heat treatment.