CERN, Geneva
This presentation will detail the performance achieved to date with all the main LHC beam instrumentation systems. It will include an overview of the beam loss system and its role in machine protection, along with that of the beam position system and its use for automatic orbit control. Results will be shown from the highly sensitive base band tune system as well as the bunch-by-bunch and DC beam current transformer systems, the synchrotron light monitoring systems, the wire scanner system and OTR screens. It will also cover the US-LARP contribution to the LHC in the form of results from the collision rate monitors developed by LBL and the Schottky monitors developed by FNAL.
ORNL, Oak Ridge, Tennessee
A new Target Imaging System (TIS) has been installed to directly measure the size and position of the proton beam on the Spallation Neutron Source (SNS) mercury target. The proton beam passing through a luminescent coating on the target nose produces light that is transported via a radiation-tolerant optical system to an image acquisition system integrated with the accelerator controls network. This paper describes the software that acquires and analyzes the image, the integration of the system with the SNS control system, and a comparison of the TIS results with the indirect methods of calculating the peak densities of the proton beam.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
The gas ionisation beam profile monitor is a well established piece of diagnostic hardware. The use of active devices such as micro-channel plates (MCP’s) and channeltrons within such a diagnostic can present problems with gain differences between channels. At the Rutherford Appleton laboratory we have produced a beam profile monitor that uses an array of 40 individually powered channeltrons; these devices were chosen over the MCP for their robustness and longer lifetimes. These channeltron devices (like MCP’s across their surface) can suffer from large variations in gain at the desired operating voltage. We have successfully shown that an additional in-built calibration system using a single, motorised , channeltron can overcome these issues. We report on the work to build the calibration system, and the 40 channeltron array. The PXI (National Instruments) system used to control the motor drive and provide the all data acquisition is also covered. Also we report the new high voltage drift field to reduce space charge effects on the beam profile. Ongoing work on understanding how the drift field as well the beam field affects the measured profile is also discussed.
Fermilab, Batavia
Ionization profile monitors (IPMs) are installed in the Fermilab Booster, Main Injector and Tevatron. They are used routinely for injection matching measurements. For emittance measurements the IPMs have played a secondary role to the Flying Wires, with the exception of the Booster (where it is the only profile diagnostics). As Fermilab is refocusing its attention on the intensity frontier, non-intercepting diagnostics such as IPMs are expected to become even more important. This paper gives an overview of the operational use of IPMs for emittance and injection matching measurements at Fermilab, and summarizes the future plans.
LANL, Los Alamos, New Mexico
The Accelerator Operations & Technology Division operates a half-mile linear particle accelerator which utilizes 110 wire scanning diagnostics devices to gain position and intensity information of the proton beam. In the upcoming LANSCE improvements, 51 of these wire scanners are to be replaced with a new design, up-to-date technology and off-the-shelf components. This document outlines the requirements for the mechanical design of the LANSCE wire scanner and presents the design currently being worked on. Additionally, it presents the decision making process for the selected components and sub-systems within the wire scanner such as the drive system, frame, mounting interface, and vacuum components. This is done by comparing design alternatives and comparing them to the objectives of the project. Similarly, a comparison between the use of a stepper motor and a servo motor is detailed in this document; this is mostly done through motor-torque calculations, back-drive calculations, and a comparison of the inherent properties of both types of motors, such as detent torque and torque capabilities. Lastly, the paper concludes with a plan for future work on the wire scanner development.
LANL, Los Alamos, New Mexico
The primary goal of this newly installed beam profile measurement is to provide the facility operators and physicists with a reliable horizontal and vertical projected beam distribution and location with respect to the proton beam target and beam aperture. During a 3000-hour annual run cycle, 5 microcoulombs of charge is delivered every 50 milliseconds through this harp to the downstream 1L target. The resulting radioactive annual dose near this harp is at least 600 MRads. Because of this harsh environment, the new harp design has been further optimized for robustness. For example, compared to an earlier design, this harp has half of the sensing wires and utilizes only a single bias plane. The sensing fibers consist of a 0.078-mm diameter SiC fiber. To hold these fibers to a rigid ceramic structure, a “collet” fiber-clamping device accomplishes the three goals of maintaining a mechanical fiber clamp, holding the sense fiber under a slight tensile force, and providing a sensing fiber electrical connection. This paper describes the harp analysis and design, and provides fabrication, assembly, and installation information, and shows how facility wiring was altered.
LANL, Los Alamos, New Mexico
A beam position reproducibility measurement was performed using the beam position monitors in the Los Alamos Proton Storage Ring. The purpose of this measurement was to gain a better understanding of the quality, errors, and repeatability associated with such a measurement. Described here is a somewhat detailed understanding of how the beam position monitor measurement is made, and the procedure for this reproducibility experiment. Data and statistical analysis, and the fitting of the turn-by-turn position data are discussed in detail. Also reported are the errors found in the data acquisition, how often the errors occur, how the errors are identified and removed from the dataset, their effect on the quality of the beam position measurement, and scenarios of how these errors manifest in the data acquisition. The resulting conclusions of the repeatability of the beam position measurement is based on the spread of fitting parameters fit to the turn-by-turn beam position data.
Cockcroft Institute, Warrington, Cheshire
The University of Liverpool, Liverpool
For destructive beam intensity measurements, electrostatic Faraday cups will be incorporated into the Ultra-low energy Storage Ring (USR) and its transfer lines at the Facility for Low-energy Antiproton and Ion Research (FLAIR). This multipurpose machine will offer both slow and fast extracted beams resulting in a wide range of intensities and varying time structure of the beam. In this contribution we present the particular challenges of measuring the beam intensity in the USR, results from numerical optimization studies, as well as the design of the cup.
Fermilab, Batavia
The Fermi National Accelerator Laboratory (FNAL) High Intensity Neutrino Sources (HINS) is a research project to address accelerator physics and technology questions for a new concept, low-energy, high-intensity long pulse H- superconducting linac. HINS will consist of a 50 keV ion source, a 2.5 MeV Radiofrequency Quadrupole (RFQ), and a 10 MeV room temperature spoke resonator acceleration section followed by superconducting spoke resonator acceleration sections. At this time a proton ion source and the RFQ module have operated with beam. This paper will present the results of first beam measurements through the HINS RFQ.
Fermilab, Batavia
A system was developed for bunch-by-bunch detection of transverse proton and antiproton coherent oscillations based on the signal from a single beam-position monitor (BPM) located in a region of the ring with large amplitude functions. The signal is digitized over a large number of turns and Fourier-analyzed offline with a dedicated algorithm. To enhance the signal, the beam is excited with band-limited noise for about one second, and this was shown not to significantly affect the circulating beams even at high luminosity. The system is used to measure betatron tunes of individual bunches and to study beam-beam effects. In particular, it is one of the main diagnostic tools in an ongoing study of nonlinear beam-beam compensation studies with Gaussian electron lenses. We present the design and operation of this tool, together with results obtained with proton and antiproton bunches.
LANL, Los Alamos, New Mexico
The heart of the LANSCE accelerator complex consists of Cockcroft-Walton-type injectors, a drift-tube linac and a side-coupled linac. These systems are approaching 40 years of age and a project to re-establish high-power capability and to extend the lifetime is underway. Many of the present beam diagnostic systems are difficult to maintain, and the original beam position monitors don’t provide any data at all. These deficiencies hamper beam tuning and trouble-shooting efforts. One thrust of the refurbishment project is to restore reliable operation of the diagnostic systems. I will describe the present diagnostic systems and their limitations, and will present requirements and solutions for the next-generation diagnostics systems.