北京正负电子对撞机的建造和调束

本文介绍北京正负电子对撞机的结构特点、工程建设情况以及能在短期内建成的原因．     

ATPF—a dedicated proton therapy facility

A proton therapy facility based on a linac injector and a slow-cycling synchrotron is proposed. To obtain good treatments for different cancer types, both the spot scanning method and the double-scattering method are adopted in the facility, whereas the nozzles include both gantry and fixed beam types. The proton accelerator chain includes a synchrotron of 250 MeV in maximum energy, an injector of 7 MeV consisting of an RFQ and a DTL linac, with a repetition rate of 0.5 Hz. The slow extraction using the third-order resonance and together with the RFKO method is considered to be a good method to obtain a stable and more-or-less homogenous beam spill. To benefit the spot scanning 200 between 60 MeV and 230 MeV. A new method method, the extraction energy can be as many as about - the emittance balancing technique of using a solenoid or a quadrupole rotator is proposed to solve the problem of unequal emittance in the two transverse planes with a beam slowly extracted from a synchrotron. The facility has been designed to keep the potential to be upgraded to include the carbon therapy in the future.     

Introduction to the overall physics design of CSNS accelerators

The China Spallation Neutron Source (CSNS) is an accelerator-based facility. The accelerator of CSNS consists of a low energy linac, a Rapid Cycling Synchrotron (RCS) and two beam transport lines. The overall physics design of CSNS accelerator is described, including the design principle, the choice of the main parameters and design of each part of accelerators. The key problems of the physics design, such as beam loss and control, are also discussed. The interface between the different parts of accelerator, as well as between accelerator and target, are introduced.     

Physical design of scanning gantry for proton therapy facility

A proton therapy facility based on a linac injector and a slow cycling synchrotron is proposed. To achieve effective treatment of cancer, a scanning gantry is required. The flexible transmission of beam and high beam position accuracy are the most basic requirements for a gantry. The designed gantry optics and scanning system are presented. Great efforts are put into studying the sensitivity of the beam position in the isocenter to the element misalignments. It shows that quadrupole shift makes the largest contribution and special attention should be paid to it.     

Irradiation methods and nozzle design for the advanced proton therapy facility

A conception design of the Advanced Proton Therapy Facility （APTF） has been carried out. The system intentionally employs a slow-cycling synchrotron with a maximum energy of 250 MeV, two rotating gantries and two fixed beam nozzles for the treatment. In this paper, we try to compare the strength and weaknesses between the two treatment methods： the beam spreading and the pencil beam scanning. The application of the pencil beam scanning method and the double-scattering method together with the related nozzle design at APTF is also given. The simulation results of employing the double-scattering method have been given during the preliminary design.     

螺旋线型迥旋加速器调变磁场曲线形式的选择

本文中对具有调变场形式为f=sin(Φ(γ)-Nφ)的螺旋形迴旋加速器作了研究,讨论了选择调变曲线形式Φ(γ)的方法,从而可求得满足某些条件下的最合适的曲线形式,该形式在加速器中心为托马斯型,在外半径区域可用几个不同参数的阿基米德螺旋线分段接近,采用这曲线后有很多优点,例可使中心区的散焦力减少到最小,非线性共振亦减弱,并且为了克服中心区的散焦力,在相同的滑相条件下,所要求的D盒加速电压亦大为降低,并使外半径区具有最大磁间隙。     

准周期聚焦–加速耦合系统的均温设计方法

强流质子直线加速器要求严格控制束流损失和束流发射度增长.理论已经证明,强的空间电荷作用在不同自由度之间的耦合,会因为其间的温度差异,通过束流的相干不稳定性,使束流发射度增长.因此,有必要按照均温的原则设计强流加速器.但是,由于质子直线加速器的各种加速结构均为准周期耦合系统,使得均温设计十分繁琐而难以达到完全均温.我们利用国际上通用的束流动力学软件TRACE3-D,给它补充了均温设计功能,通过与PARMILA程序的配合使用,可以方便地在加速器设计中实现均温条件.本文将介绍我们对TRACE3-D的修改补充,并以强流质子直线加速器设计实例,说明均温设计的必要性.     

BPS的束团同步传输方法

本文针对曾经设计的北京质子同步加速器(简称BPS)其增强器引出能量接近临界能量的特点,提出了主加速器与增强器周比不严格等于高频谱波数之比的束团同步传输方法,并对该方法的物理图象及有关参数的选择原则作了探讨。     

北京散裂中子源快循环同步环磁聚焦结构设计

快循环同步环(RCS)是北京散裂中子源(BSNS)的一个重要组成部分, 其物理设计对加速器的性能和造价起到决定性作用. 文章研究了能满足北京散裂中子源~RCS~要求的几种磁聚焦结构, 给出了一个三折结构的详细设计, 并比较分析了其他可供选择的磁聚焦结构.     

RFQ加速器束流接受度的计算

基于RFQ加速器中束流横向运动方程描述了一种计算其入口处束流接受度的方法.针对特定结构参数的四翼型RFQ加速器,给出了计算结果为:加速质子束时的系统接受度在x-x′平面为0.0153cm·rad,在y-y′平面为0.0114cm·rad.此方法也适用于求解其它已知结构、使用射频场加速、线性横向电场的加速器的接受度.