Antiproton beam parameters measurement by a new digital-receiver-based system

The Antiproton Decelerator (AD) provides the users with very low intensity beams, in the 107 particles range, hence prompting the development of an innovative measuring system, which was completed in early 2000. This system measures antiproton beam intensity for bunched and debunched beams, together with momentum spread and mean momentum for debunched beams. It uses a state-of-the-art Digital Receiver board, which processes data obtained from two ultra-low-noise, wide-band AC beam transformers. These have a combined bandwidth in the range 0.02 MHz - 30 MHz and are used to measure AC beam current modulation. For bunched beams, the intensity is obtained by measuring the amplitude of the fundamental and second RF Fourier components. On the magnetic plateaus the beam is debunched for stochastic or electron cooling and longitudinal beam properties (intensity, momentum spread and mean momentum) are measured by FFT-based spectral analysis of Schottky signals. The system provides real-time information characterising the machine performance; it has been used for troubleshooting and to fine-tune the AD, thus allowing further improved performance. This system has been operating since May 2000 and providing beam intensity data to the users on a routine basis since late 2000. A dedicated software package was expressly developed to take care of the control, data acquisition and processing phases. It consists of three main codes, namely a GUI, a Real Time Task and a Low Level Code. This report gives an overview of both the hardware and software developed

OASIS User Manual

The OASIS system has been operational for years now. After a long development the project has reached a state where the number of features it provides exceeds largely what most of its users knows about. The author felt it was time to write a user manual explaining all the functionality of the viewer application. This document is a user manual, concentrating on the functionality of the viewer from the user’s point of view. There are already documents available on the project’s web site about the technical aspects at http://project-oasis.web.cern.ch/project-oasis/presentations.htm . There was an attempt to produce a tutorial on the viewer, but it didn’t get much further than the table of contents, that however is well thought. The structure of this user manual follows the same principle, the basic and most often used features are grouped together. Advanced or less often used features are described in a separate chapter. There is a second organizational principle, features belong to different levels: channel, scope or application level. This makes easier to find information in this manual

AD Ejection Line Studies and Optics Improvements

This paper is a summary of the work we made to understand and improve the AD ejection line optics. In 2011 significant differences were noticed between the optical properties of the AD ejection line and the MAD model. Investigations started to find out the sources of discrepancy. Better understanding of the ejection line optics was obtained and corrections were applied to the model of ejection line. The beam delivery to the experiments is better understood now. The results obtained might be useful as well for the optics design of AD to ELENA transfer line. Potential problems with the fringing field model in MAD were pointed out, when bending magnets with large bending angles and small bending radius are involved

CERN Antiproton Decelerator Beam Instrumentation for the ELENA era

CERN is currently constructing an Extra Low ENergy Antiproton ring (ELENA), which will allow the further deceleration of antiprotons from the currently exploited Antiproton Decelerator (AD). In order to meet the challenges of ELENA the beam instrumentation systems of the CERN AD are being consolidated and upgraded. An updated controls architecture with a more flexible timing system needs to be adopted and obsolete systems must be replaced. This paper presents the status and plans for improved performance and measurement availability of the AD beam instrumentation with a decreased risk of failure

OASIS: STATUS REPORT

OASIS, the Open Analogue Signal Information System, is the LHC era system for the acquisition and display of analogue signals in the accelerator domain. OASIS is based on a three-tier architecture. The upper layer is an application written in Java. It is responsible for waveform display and user interaction. The application server, in the middle tier, uses the OC4J J2EE container and is based on the Enterprise Java Beans. This part takes care, among other things, of the signal connection and the management of the connection settings. The front-end tier is implemented within the FESA framework and controls oscilloscopes and analogue matrices in CompactPCI and VXI format. Today, most of the performance critical features such as the mountain range mode or the scrolling mode have been implemented. However, the problem of remote trigger has still to be addressed. The system was successfully put in production for the TT40/TI8 tests with a small configuration. The next, and bigger, installation is the LEIR machine where OASIS has to be available twenty four hours a day for a longer period and has to handle more than 200 signals

Cost and Feasibility Study of the Intensity Improvement for ASACUSA

An electron cooling scheme for an antiproton beam confined into a h = 1 bucket in the CERN Antiproton Decelerator (AD) is proposed. The longitudinal beam density obtained this way is significantly higher than what can be achieved by cooling a coasting beam, allowing beam bunching with 202 MHz already in the AD ring, the frequency of the ASACUSA decelerating RF quadrupole (RFQD). The scheme requires installation of two 202 MHz cavities and a wall current monitor into the AD. With such a modest investment ASACUSA will gain a factor of 2-3 in intensity. In this paper a detailed list of the work needed in order to implement the proposal is compiled, as well as a first cost estimate

Upgrades to the Digital Receiver based Low-Intensity Beam Diagnostics for CERN AD

The CERN AD Low-Intensity Beam Multi-Diagnostics (LIMD) has been upgraded as planned since 2001 by adding tune measurements during ramps and plateaus, based on the Beam Transfer Function (BTF) method. This relies on transversally exciting the beam by a deflector and deriving the BTF and coherence function from FFTs of excitation and beam response recorded by digital receivers (DRX). These, continuously tuned to a betatron sideband, pass data to a digital signal processor (DSP) on the DRX board for data processing. The upgrades discussed also include increased longitudinal frequency range, noise reduction measures and digital flags for setup of Data Acquisition (DAQ) and processing parameters

AD status and consolidation plans

The CERN Antiproton Decelerator (AD) has now completed its 12th year of supplying low-energy antiproton beams for the successful physics program. Most of the machine’s key components are in operation since more than 25 years and prompted by the approval of the ELENA project, a substantial consolidation program is now being launched to ensure continued reliable operation. Over the course of the next few years a progressive renovation of the AD-Target area and the AD-ring with all the associated systems will take place. Status and performance of the AD are presented along with an overview of planned and ongoing consolidation activities with emphasis on stochastic and electron beam cooling