摘要:

The idea of using the non‐linearities of beam position monitors to measure the second moment&sgr;x2 − &sgr;y2of the transverse beam distribution is almost as old as the synchrotron. However, although a few successful experiments have been reported, the method has not become widely accepted. One reason for this has been that little or no effort was put into optimizing the pick‐ups that were used for the new purpose. In a standard beam position pick‐up, the signal from the second moment is extremely weak and embedded in a strong common‐mode background. Separating the signal from the background has therefore been a major stumbling block. Driven by the need for a non‐destructive measurement of injection matching to preserve the small emittance of the LHC beam, a dedicated quadrupole pick‐up has been developed for the CERN PS. The design employs magnetic coupling in a special pick‐up geometry to remove the otherwise dominating background signal, thereby reducing the common‐mode rejection requirements by about 60 dB. Two pick‐ups have been installed in the machine. When the data from these pick‐ups is combined, it is possible to measure both the matching parameters and the emittance of each bunch in the injected beam. This paper gives an overview of the pick‐up design, describes the methods used to analyze the data, and presents some measurement results, including comparisons with other instruments in the machine. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1524389

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

We present an introduction to the operating principles of free‐electron lasers, discussing the amplification process, and the requirements on the electron beam necessary to achieve desired performance. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1524390

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The beam loss monitoring system is one of the two most widely distributed beam diagnostic systems at most particle accelerator facilities. This tutorial reviews the characteristics of the ionizing radiation from beam losses, and the properties of beam loss radiation detectors. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1524391

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Radiation generated by high‐energy particle beams is widely used to characterize the beam properties. While the wavelengths of radiation may vary from visible to x‐rays, the physics underlying the engineering designs are similar. In this tutorial, we discuss the basic considerations for the optical system design in the context of beam instrumentation and the constraints applied by high‐radiation environments. We cover commonly used optical diagnostics: fluorescence flags, visible and x‐ray synchrotron radiation imaging. Emphases will be on achieving desired resolution, accuracy, and reproducibility. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1524392

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The potentially lucrative wireless market has led to technological advances in mixed signal devices such as high speed, high resolution A/D and D/A converters. This same market has also driven the development of high performance multi‐channel digital receiver and digital transmitter ICs. Similarly, advances in semiconductor processes, coupled with the need for reduced time‐to‐market, has led to the development of large, enhanced performance, in‐circuit programmable logic devices. A review of the key characteristics of these mixed‐signal, signal processing and programmable logic devices is presented. The application of these devices and technologies to the instrumentation of Accelerators and Storage Rings is discussed and presented by way of examples. Issues relating to the requirements associated with real‐time processing, I/O throughput, reconfigurability, reliability, maintainability and packaging requirements are also addressed. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1524393

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Experience gained during the recent commissioning of the Main Injector accelerator and the Recycler storage ring at Fermilab will be discussed. Some of the more interesting problems involve; ground differences, cabling for bpm and multiwire systems, electromagnetic noise, and magnetic shielding. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1524394

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

In this paper, the electron beam diagnostics developed for recirculating electron accelerators will be reviewed. The main novelties in dealing with such accelerators are: to have sufficient information and control possibilities for the longitudinal phase space, to have means to accurately set the recirculation path length, and to have a means to distinguish the beam passes on measurements of position in the linac proper. The solutions to these problems obtained at Jefferson Laboratory and elsewhere will be discussed. In addition, more standard instrumentation (profiling and emittance measurements) will be reviewed in the context of recirculating linacs. Finally, and looking forward, electron beam diagnostics for applications to high current energy recovered linacs will be discussed. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1524395

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Three basic tune measurement methods are employed in RHIC; kicked beam, Schottky, and phase‐locked loop. The kicked beam and 2GHz Schottky systems have been in operation since the first commissioning of circulating beam in RHIC in 1999. Preliminary PLL measurements utilizing a commercial off‐the‐shelf lockin amplifier were completed during that run, and the resonant BPM used in that system also delivered 230MHz Schottky spectra. With encouraging preliminary results and the thought of tune feedback in mind, a PLL tune system was implemented in the FPGA/DSP environment of the RHIC BPM system for the RHIC 2001 run. During that run this system functioned at the level of the present state‐of‐the‐art in tune measurement accuracy and resolution, and was successfully incorporated into a tune feedback system for use during acceleration. Each of the tune measurement systems has particular strengths and weaknesses. We present specific and comparative details of systems design and operation. In addition, we present detailed tune measurements and their utilization in the measurement of chromaticity and the implementation of tune feedback. Finally, we discuss planned upgrades for the RHIC 2003 run. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1524396

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

A beam profile monitor for H−beams based on laser photoneutralization is being developed at Brookhaven National Laboratory (BNL) for use on the Spallation Neutron Source (SNS) [1]. An H−ion has a first ionization potential of 0.75eV and can be neutralized by light from a Nd:YAG laser (&lgr;=1064nm). To measure beam profiles, a narrow laser beam is passed through the ion beam neutralizing a portion of the H−beam struck by the laser. The laser trajectory is stepped across the ion beam. At each laser position, the reduction of the beam current caused by the laser is measured. A proof‐of‐principle experiment was done earlier at 750keV. This paper reports on measurements made on 200MeV beam at BNL and with a compact scanner prototype at Lawrence Berkeley National Lab on beam from the SNS RFQ. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1524397

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

With the emergence of 4th generation FEL based light sources there is now considerable interest in both producing and characterizing ultra‐short (<100 fs) electron bunches. Knowledge of the extremely high peak current in a short bunch is required to diagnose the SASE (self amplified stimulated emission) process. Measuring the femtosecond duration of the pulse is inherently interesting, particularly for experimenters using the beam to measure fast phenomena (e.g. femto‐chemistry). Diagnostic techniques that have the necessary femtosecond resolution will be reviewed: These include high‐power RF transverse deflecting structures that “streak” the beam in the accelerator allowing the bunch length to be recorded on a profile monitor. Electro optic crystal diagnostics use the electric field of the electron bunch to modulate light thereby exploiting the femtosecond technology of high bandwidth visible lasers. Coherent synchrotron radiation (CSR) from dipole magnets and optical diffraction radiation (ODR) both result in radiation with wavelengths of the order of the bunch length and hence in the terahertz band which can be detected by a variety of techniques. The role of each of these techniques is discussed in terms of its application at the Linac Coherent Light Source (LCLS) and the Short Pulse Photon Source (SPPS) currently under construction at SLAC. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1524398

出版商:AIP    

年代:1902

数据来源: AIP