A data transmission method for particle physics experiments based on Ethernet physical layer

Due to its advantages of universality, flexibility and high performance, fast Ethernet is widely used in readout system design for modern particle physics experiments. However, Ethernet is usually used together with the TCP/IP protocol stack, which makes it difficult to implement readout systems because designers have to use the operating system to process this protocol. Furthermore, TCP/IP degrades the transmission efficiency and real-time performance. To maximize the performance of Ethernet in physics experiment applications, a data readout method based on the physical layer(PHY) is proposed. In this method, TCP/IP is replaced with a customized and simple protocol, which makes it easier to implement. On each readout module, data from the front-end electronics is first fed into an FPGA for protocol processing and then sent out to a PHY chip controlled by this FPGA for transmission.This kind of data path is fully implemented by hardware. From the side of the data acquisition system(DAQ),however, the absence of a standard protocol causes problems for the network related applications. To solve this problem, in the operating system kernel space, data received by the network interface card is redirected from the traditional flow to a specified memory space by a customized program. This memory space can easily be accessed by applications in user space. For the purpose of verification, a prototype system has been designed and implemented.Preliminary test results show that this method can meet the requirements of data transmission from the readout module to the DAQ with an efficient and simple manner.     

Hadron production experiments for neutrino physics

Precision neutrino experiments require input from hadron production experiments to be able to reach their design aims. Some of these hadron yield experiments are discussed. In particular the recent pion yield measurement from HARP for the K2K neutrino beam is shown.     

开放式物理实验交流平台及教学辐射作用

为了满足大学生多元化学习需要,目前高校物理实验教学内容丰富、教学形式多样,而操作简易化却使教与学双方部分忽视了物理实验的教学意义.基于"广东省大学生物理实验设计大赛"所构建的开放式物理实验教学交流平台与物理实验示范中心作用互补,在有效利用高校现有教学资源基础上,通过关注物理实验测量基本原理和实验物理相关性,促进实验教学方法改革,提高物理实验教学质量.交流平台超越《教育部高等院校物理实验基础教学示范中心建设标准》示范要求,教学受益面广泛,辐射"靶向"作用直接、明确.     

物理学中的示零实验

示零实验采用完全补偿法 ,在物理实验中具有独特的作用 .本文介绍了示零实验在提高测量精度、修正系统误差和为理论提供依据方面的特殊功能     

农科物理实验引入研究性实验的尝试

探讨了农科物理实验引入研究性实验的必要性和意义，结合农科院校的特色，以研究油菜种子超微弱发光为例，进行了有益的尝试。     

将近代物理内容加入"大平台"普通物理实验

介绍了将近代物理内容加入“大平台”普通物理实验的具体情况.     

演示实验和文科物理教学

阐述了物理演示实验在高校文科物理教学中的作用、意义及在复旦大学的实施情况．     

利用模糊数学对学生物理实验进行综合评价

介绍了用模糊数学对学生物理实验进行综合评价的方法,避免了常规考试方法的许多弊端。     

定性与半定量物理实验教学初探

近年来，复旦大学在物理实验教学中适当加入了一批定性与半定量实验，实践证明，该类实验有利于培养学生分析问题与解决问题的能力，增强科学洞察力与判断力，激发他们的求知欲与创新精神，提高其科学素质．本文介绍了开设这些实验的经验、体会及初步效果．     

A novel approach for analyzing open Z-scan experiments

In this work, a novel method for analyzing open Z-scan experiments is presented. It is based on the calculation of the nonlinear absorption parameter q directly from the transmittance measurements. Specifically, we have found an analytic formula describing the dependence of the parameter q on the normalized transmittance. The influence of noise has been studied and the method was proved robust even under conditions of relatively high noise. Extension to the general case of an elliptic Gaussian incident beam has also been realized. The technique has been experimentally tested by analyzing transmittance measurements obtained from a recently synthesized pyrylium salt, illuminated by a femtosecond laser system. The results are in very good agreement with those obtained by the standard Z-scan analysis, especially regarding the nonlinear absorption coefficient β.     

Quantum statistical physics: A new approach

The new scheme employed (throughout the “thermodynamic phase space”), in the statistical thermodynamic investigation of classical systems, is extended to quantum systems. Quantum Nearest Neighbor Probability Density Functions (QNNPDF's) are formulated (in a manner analogous to the classical case) to provide a new quantum approach for describing structure at the microscopic level, as well as characterize the thermodynamic properties of material systems. Since QNNPDF's describe microstructure in “random neighborhoods”, the new scheme may be viewed as an “elastic cavity” approach (with “elastic” walls). A major point of this paper is that it relates the free energy of an assembly of interacting particles to QNNPDF's. Application to the simple case of dilute, weakly degenerate gases has been outlined.     

Superthermal source of ultracold neutrons for fundamental physics experiments

Ultracold neutrons (UCNs) play an important role for precise measurements of the properties of the neutron and its interactions. During the past 25 years, a neutron turbine coupled to a liquid deuterium cold neutron source at a high-flux reactor has defined the state of the art for UCN production, despite a long history of efforts towards a new generation of UCN sources. This Letter reports a world-best UCN density available for users, achieved with a new source based on conversion of cold neutrons in superfluid helium. A conversion volume of 5 liters provides at least 274,000 UCN in a single accumulation run. Cyclically repeated operation of the source has been demonstrated, as well.     

A comprehensive approach to new physics simulations

We describe a framework to develop, implement and validate any perturbative Lagrangian-based particle physics model for further theoretical, phenomenological and experimental studies. The starting point is FeynRules, a Mathematica package that allows to generate Feynman rules for any Lagrangian and then, through dedicated interfaces, automatically pass the corresponding relevant information to any supported Monte Carlo event generator. We prove the power, robustness and flexibility of this approach by presenting a few examples of new physics models (the Hidden Abelian Higgs Model, the general Two-Higgs-Doublet Model, the most general Minimal Supersymmetric Standard Model, the Minimal Higgsless Model, Universal and Large Extra Dimensions, and QCD-inspired effective Lagrangians) and their implementation/validation in FeynArts/FormCalc, CalcHep, MadGraph/MadEvent, and Sherpa.     

新型数据采集系统芯片ADμC812在物理实验中的应用

ADμC812是新一代数据采集系统芯片，它将A／D，D／A转换器与8051完全兼容的内核等器件集成在一块芯片上，利用ADμC812的ISP功能，可制造出具有远程升级能力的智能化仪器；利用ADμC812的DMA功能，能解决物理实验中某些需要进行高速数据采集的问题。     

Searching for new physics in future neutrino factory experiments

An extension of the new standard model, by introducing a mixing of the low mass “active” neutrinos with heavy ones, or by any model with lepton flavor violation, is considered. This leads to non-orthogonal neutrino production and detection states and to modifications of neutrino oscillations in both vacuum and matter. The possibility of the discovery of such effects in current and future neutrino oscillation experiments is discussed. First order approximation formulas for the flavor transition probabilities in constant density matter, for all experimentally available channels, are given. Numerical calculations of flavor transition probabilities for two sets of new physics parameters describing a single “effective” heavy neutrino state, both satisfying present experimental constraints, have been performed. Two energy ranges and several baselines, assuming both the current (±2σ) and the expected future errors (±3%) of the neutrino oscillation parameters are considered, keeping their present central values. It appears that the biggest potential of the discovery of the possible presence of any new physics is pronounced in oscillation channels in which ν_e and ν_ē are not involved at all, especially for two baselines, L=3000 km and L=7500 km, which for other reasons are also called “magic” for future Neutrino Factory experiments. PACS 13.15.+g; 14.60.Pq; 14.60.St     

基于物理实验的SSL网络教学模式的研究

依据物理实验学科的特点,构建了SSL网络教学模式,旨在促进物理实验学科的网络化,并提高学生思维、协作、动手等能力,同时减轻任课教师的压力. 介绍了SSL网络教学模式的构建和教学环节的具体实施方式.     

Torsion balance experiments: A low-energy frontier of particle physics

We review recent mechanical experiments that test some of the most basic principles of physics including the weak and strong forms of the Equivalence Principle, the gravitational inverse-square law, and Lorentz invariance. The very high sensitivity of these tests allows one to place interesting constraints on string-theory inspired conjectures about new Yukawa forces from the exchange of very light scalar, pseudoscalar or vector particles, large extra dimensions, the chameleon mechanism, non-commutative spacetime geometry, and Planck-scale Lorentz violation.     

“旋转”在物理学实验中的运用及作用

通过对几个典型的与旋转相关物理学实验的分析,阐述了旋转在实现实验目的方面起到的作用.