ANL, Argonne
The Advanced Photon Source (APS) monopulse beam position monitor (BPM) system, designed to measure single- and multi-turn beam positions, is one of three BPM systems currently in use to measure and control both AC and DC orbit motions. Recently, one sector of the monopulse BPM system was upgraded by replacing its ca 1992 12-bit signal conditioning and digitizing unit (SCDU) with a field-programmable gate array (FPGA)-based system for signal processing. The system is comprised of a repackaging of the broadband rf receiver modules together with a VME Extensions for Instrumentation (VXI) module housing eight 14-bit digitizers and one FGPA. The system will be described in detail, including an overview of its new functionality, and performance will be discussed. Of particular interest is the noise floor, which will be contrasted with the previous system and with other systems in use at the APS.
JLAB, Newport News, Virginia
CNU, Newport News, Virginia
Beamline components used for diagnostic elements often rely on thermal stabilization, continual physical maintenance (ie. tuning), and frequent beam-based calibrations to maintain specified performance. Direct-sequence spread spectrum (DSSS) pilot tones injected into a particular element and combined with the beam-derived signal can subsequently be separated and used to assess performance degradation. In addition, the DSSS tone can be used as a real-time calibration signal, without interference to the intended diagnostic signal. This paper demonstrates such a technique in the design of a Beam Current Monitor downconverter system, as an intended upgrade to the CEBAF Beam Loss Accounting system. A brief spread-spectrum primer is included, as well as a description of appropriate spreading codes and their generation.
IHEP Beijing, Beijing
A DC Current Transformer (DCCT) as a standard diagnostic system for beam current plays an important role in BEPCII, the upgrade project of the Beijing Electron Positron Collider. Two DCCTs are operated in the BEPCII storage ring now, separated in electron ring and positron ring, used to monitor the beam current, the beam injection rate and the beam loss rate, meanwhile to help to calculate the beam lifetime. In this paper, the mechanical structure design, readout system and data processing are presented. The progress of DCCTs on each step of BEPCII commissioning, such as improving the beam lifetime，and solution of background noise, are also included.
LANL, Los Alamos, New Mexico
The LANSCE accelerator facility utilizes 110 wire scanner devices to monitor the accelerator's charged particle beam. The LANSCE facility's existing wire scanner control systems have remained relatively unchanged since the LANSCE accelerator became operational in the 1970's. The evolution of motion control technologies now permits the development of a wire scanner motion control system that improves in areas of energy efficiency, precision, speed, resolution, robustness, upgradeability, maintainability, and overall cost. The purpose of this project is to research the capabilities of today's motion control products and analyze the performance of these products when applied to a wire scanner beam profile measurement. This experiment's test bed consists of a PC running LabVIEW, a National Instruments motion controller, and a LEDA (Low Energy Demonstration Accelerator) actuator. From this experiment, feedback sensor performance and overall motion performance (with an emphasis on obtaining maximum scan speed) has been evaluated.
I-Tech, Solkan
ESRF, Grenoble
Libera, the beam position processor, features the so-called Turn-by-Turn (TbT) data output, the data rate being exactly the revolution frequency of the accelerator. This data is essential for commissioning of the accelerator as well as for various machine physics studies. However, due to the "natural" properties of correctly structured filters (respecting the Nyquist theorem), the smearing between adjacent TbT samples is not negligible. The purpose of the modified DDC filter is to remove smearing between adjacent TbT samples, especially with partial fill patterns. The usage of Modified DDC filters gives the best results for the studies using the Turn-by-Turn measurements, with the benefit of "true & pure" Turn-by-Turn results (no smearing). The method, its implementation and first results are discussed in this paper.
ORNL, Oak Ridge, Tennessee
The original wire-scanner software was written by one of the Spallation Neutron Source (SNS) partners, Los Alamos National Laboratory. This software was designed for the types of wire-scanners initially planned and their planned usage at that time. New variations in the wire-scanner hardware added gearing, different position read-back methods, and a timing card. The new software handles these additional hardware variations in a flexible manner through configuration files. The software upgrade allows the user to synchronize the stepping of the fork with external applications, such as loss monitors to study the losses caused by the wire. Another new functionality allows you to change what part of the beam pulse is used to determine the transverse profile after the data has been taken. This avoids having to do time consuming rescans if the timing was not perfectly setup. The new software, also a LabVIEW program, is structured around a state-machine with sequence capability to manage the complexities of stepping through a scan and interacting with the user. This paper discusses the features of the new software, the implementation, and the obtained results.
JLAB, Newport News, Virginia
In this contribution we present results of the timing jitter and energy modulation of the electron beam in the driver energy recovery linac (ERL) for the JLab FEL. Measurements techniques are described. The effects of the timing jitter and the energy modulation on the performance of the FEL are discussed.
SOLEIL, Gif-sur-Yvette
The Soleil Fast Orbit Feedback System has been integrated in the BPM electronics, using the FPGA resources of the Libera modules. On top of their position measurement, the FPGAs compute the orbit correction and drive the power-supplies of the 48 dedicated air coil correctors. Position data are distributed all over the ring by a dedicated network connecting the 120 BPMs modules together. The correction rate is 10 kHz and is applied with low latency. At almost all the source points, the high frequency stability specifications have already been achieved thanks to great care in the design of the machine. Remaining vibrations are still observed in the 46-54 Hz band and during the change in gap and phase of some insertion devices. Those perturbations are efficiently damped by the fast orbit feedback system. The BPM system has been operational for some time. The fast orbit feedback system is in its commissioning phase. The design and first results of the latter are reported.
LBNL, Berkeley, California
The Advanced Light Source (ALS) in Berkeley was the first third generation light source ever built, and since 1993 has been in continuous and successful operation serving a large community of users in the VUV and soft x-ray community. During these years the storage ring underwent through several important upgrades that allowed to maintain the performances of this veteran facility at the forefront. The ALS beam diagnostics and instrumentation have followed a similar path of innovation and upgrade and nowadays include most of the modern and last generation devices and technologies that are commercially available and used in the recently constructed third generation light sources. In this talk we will not focus on such already widely known systems, but we will concentrate in the description of some measurements techniques, instrumentation and diagnostic system specifically developed at the ALS and used during the last few years.
KIP, Heidelberg
GSI, Darmstadt
The development of new particle accelerators with unprecedented beam characteristics has always driven the need for an intense R&D program in diagnostic techniques. The successful operation of these machines is finally only possible with an adequate set of beam instrumentation. DITANET is a large European network between several research centres, Universities, and partners from industry that aims for the development of beyond-state-of-the-art diagnostic techniques for future accelerator facilities. This includes research projects focusing on beam profile, current, and position measurements, as well as on particle detection techniques and related electronics. A particular focus of the consortium is the training of young researchers in this multi-disciplinary field and to thus prepare them for their future careers in academia or industry. This contribution will introduce the network participants, present the general structure of DITANET, and give an overview of its research and training activities.