LBNL, Berkeley, California
SLAC, Menlo Park, California
The scientific potential of femtosecond x-ray pulses at linac-driven FELs such as the LCLS is tremendous. Time-resolved pump-probe experiments require a measure of the relative arrival time of each x-ray pulse with respect to the experimental pump laser. In order to achieve this, precise synchronization is required between the arrival time diagnostic and the laser, which are often separated by hundreds of meters. We describe an optical timing system based on stabilized fiber links which has been developed for the LCLS to provide this synchronization. Preliminary results show synchronization of the synchronization signals at the sub-10 fsec level and overall synchronization of the x-ray and pump laser of <40 fsec. We present details of the implementation and LCLS and potential for future development.
ZTEC Instruments, Albuquerque
Modular oscilloscopes and digitizers, including those with embedded EPICS IOCs, provide powerful off-the-shelf solutions for accelerator controls and beamline data acquisition applications requiring fast sampling, high resolution and/or tight multi-channel synchronization. This presentation discusses features and capabilities of EPICS and non-EPICS LXI, VXI, PXI and PCI oscilloscopes and digitizers as they specifically relate to accelerator and beamline applications. Modular oscilloscopes and digitizers with on-board DSP and FPGAs provide the advanced waveform acquisition and analysis capabilities of benchtop instruments with the size and channel-density advantages of modular instruments. Instruments with on-board processing, such as those from ZTEC Instruments, enable real-time waveform math and waveform parameter analysis. Advanced triggering and multiple acquisition modes are other features found on some of today’s advanced modular instruments. Furthermore, instruments with embedded EPICS IOCs save users the time and money of developing their own EPICS drivers and display panels. Examples of specific accelerator applications using advanced modular instruments will be presented.
National Instruments, Austin
Since 1976, National Instruments (NI) has taken off-the-shelf semiconductor and computing technology and applied it to measurement, diagnostics and instrumentation needs. NI leverages the rapid technological advancement of the semiconductor and computer industry, while retaining the flexibility and ensuring interoperability between HW & SW. This technical session will focus on the various models of computation, multicore technology applied to measurement and diagnostic needs, communication protocols, timing and synchronization, and FPGA designed-in to meet custom needs. Additionally we will see examples of Graphical System Design being applied at CERN, Max Planck, LANL, ESO and how COTS HW & SW technologies can be used to solve instrumentation needs.
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.
BNL, Upton, Long Island, New York
Four ionization profile monitors (IPMs) in RHIC measure vertical and horizontal beam profiles in the two rings. These work by measuring the distribution of electrons produced by beam ionization of residual gas. In 2007 a prototype of a new design was installed in the yellow ring. During the 2007-2008 run it proved to be almost completely free from backgrounds from rf coupling, electron clouds and x-rays from upstream beam loss. In 2009 two more IPMs of this new design were installed and in the 2010 shutdown we will complete installation of four identical IPMs. This paper describes the new IPMs and shows data from the 2010 beam run. The new IPMs have been extremely important in the commissioning of the RHIC stochastic cooling system.
NSTec, Los Alamos, New Mexico
LANL, Los Alamos, New Mexico
An optical diagnostic instrument developed for the acquisition of high-speed time-resolved images has been fielded at the Dual-Axis Radiographic Hydrodynamic Test (DARHT) Facility at Los Alamos National Laboratory. The instrument was developed for the creation of time histories of electron-beam cross-section through the collection of Cerenkov light. This is accomplished through four optical lines of sight that optically collapse an image, an optical fiber relay, recording instruments, and a tomographic reconstruction algorithm. The instrument may be operated, adjusted, and calibrated remotely due to potential adverse environmental conditions. The instrument was operated over the course of various activities during and after DARHT commissioning, and tomographic reconstructions reported verifiable beam characteristics. Results from the collected data and reconstructions and analysis of the data are discussed.
LANL, Los Alamos, New Mexico
This study evaluates a technique for the closed-loop position and velocity control of a wire scanner actuator. The focus of this technique is to drive a stepper motor-driven actuator through a 1-mm move using a combination of velocity feedback control and position feedback control. More specifically, the velocity feedback control will be utilized to provide a smooth motion as the controller drives the actuator through a pre-planned motion profile. Once the controller has positioned the actuator within a certain distance of the target position, the controller will transition to position-based feedback control, bringing the actuator to its target position and completing the move. Position and velocity data is presented detailing how the actuator performed relative to its commanded movement. Finally, the layout of, and algorithms employed by the wire scanner control system are presented.
ELETTRA, Basovizza
Several diagnostic instruments for the FERMI@Elettra FEL, among them the Bunch Arrival Monitor (BAM) and the Cavity Beam Position Monitor (C-BPM), require accurate readout, processing, and control electronics. All systems must be also integrated within the main machine control system. The back-end platform, based on the MicroTCA standard, provides a robust environment for accommodating such electronics, including reliable infrastructure features. Two types of Advanced Mezzanine Cards (AMC) had been developed in-house and manufactured for meeting the demanding performance requirements. The first is a fast (160 MSps) and high-resolution (16 bits) Analog to Digital and Digital to Analog (A|D|A) Convert Board, hosting 2 A-D and 2 D-A converters controlled by a large FPGA (Virtex-5). The FPGA is also responsible for service and host interface handling. The latter board is Analog to Digital Only (A|D|O) Converter, derived from the A|D|A, with an analog front side stage made of four A-D converters. The overall systems’ architectures, together with the specific AMCs’ functionalities, are described. Results on performance measurements are also presented.
SLAC, Menlo Park, California
A new stripline beam position monitoring (BPM) readout and processing system was installed and successfully tested over a two-week period at the Accelerator Test Facility 2 (ATF2), in KEK, Japan during February 2010. The core analog processing board used in the system is a duplicate of that developed for, and in use at, the Linac Coherent Light Source (LCLS) at SLAC. The digitization, processing and control front-end were custom designed for ATF2 using a 14-bit 100-MHz VME digitizer and an EPICS Input/Output Controller (IOC) running on the VME controller. Control of the analog boards is via EPICS, which controls a serial-over-TCP/IP port server. Hardware for the readout of up to 14 BPMs with 3 spare analog boards was delivered. The goal of this installation was to provide ~<10 micron resolution, non-charge-dependent readout of the ATF2 electron beam with long-term gain stability compensation. These criteria were tested and successfully met. This design was found to be highly effective and to have many advantages, especially that it required minimal installation effort at ATF2.
Fermilab, Batavia
Fermilab is jointly developing capabilities in high gradient and high Q superconducting accelerator structures based on the 1.3 GHz TESLA technology. Based on an INFN/TESLA design, a wire-position-monitor (WPM) system is integrated to monitor cavity alignment and cold mass vibrations. The system consists of a reference wire carrying a 325 MHz signal, 7 stripline pickups (per cryomodule), and read-out electronics using direct digital signal down-conversion techniques. We present technical details of the system, and preliminary results on resolution and stability measured at a mock-up test stand.
BNL, Upton, Long Island, New York
An internal R&D program has been undertaken at BNL to develop an RF BPM to meet all requirements of both the injection system and storage ring. The RF BPM architecture consists of an Analog Front-End (AFE) board and a Digital Front-End board (DFE) contained in a 1U 19" chassis. An external passive RF signal processor has been developed that will be located near the RF BPM pickups. The partitioning into two boards enables a flexible Software Defined Instrument. A model-based design flow has been adopted utilizing AWR VSS, Simulink, and Xilinx System Generator for algorithm development and AFE impairment performance analysis. The DFE architecture consists of a Virtex-6 with MicroBlaze embedded processor. An optional Intel Atom SBC is also supported. The AFE is based on a bandpass sampling architecture utilizing 16-bit ADCs. Long-term drift is corrected by inclusion of an out-of-band calibration tone. An RF BPM Calibration Tool is being developed for removal of systematic errors and performance verification. In this contribution we will present a detailed overview of the architecture, compare simulation results to laboratory performance, and report beam test results.
CEA, Gif-sur-Yvette
IPN, Orsay
The European XFEL is a research facility, currently under construction in Germany. It is based on a superconducting electron linac including about 100 cryomodules based on the TESLA technology. Each cryomodule is equipped with a beam position monitor connected to a quadrupole at the high-energy end of the cavity string. Around one third of cold BPMs will be re-entrant RF cavities. This contribution will describe the present status of the cold re-entrant cavity BPM, and will present measurements of the BPM pickup and electronics prototypes.
CERN, Geneva
The fast beam current transformers (FBCTs) for the Large Hadron Collider (LHC) were designed to provide bunch to bunch and turn by turn intensity measurements. The required bunch to bunch measurements together with a large machine circumference call for stringent control of the transmission bandwidth, droop and DC offsets in the front-end electronics. In addition, two measurement dynamic ranges are needed to achieve the required measurement precision, increasing the complexity of the calibration. This paper reports on the analysis of the measurement and calibration methods, discusses theoretical precision limits and system limitations and provides a comparison of the theoretical results with the real data measured during the LHC start-up.
MEPhI, Moscow
DESY Zeuthen, Zeuthen
The Photo Injector Test Facility at DESY, Zeuthen site (PITZ) develops electron sources of high brightness beams, required for linac based free electron lasers (FELs) like FLASH or the European XFEL. One of the key issues in electron beam optimization is the minimization of the transverse emittance. The main method to measure emittance at PITZ is a single slit scan technique, implying local beam divergence measurement by insertion of the slit mask at a definite location within the beam and measurements of the transmitted beamlet profile downstream of the slit station. “Emittance Measurement Wizard” (EMWiz) is the program used by PITZ operators for automated emittance measurements. EMWiz combines an acquisition program for beam and beamlet image recording and a postprocessing tool for the analysis of the measured transverse phase space of the electron beam. It provides a way to execute the difficult emittance measurements in an automatic mode and to get a calculated emittance result.
ANL, Argonne
LBNL, Berkeley, California
A bunch-by-bunch tune measurement system is a very powerful tool for beam diagnostics and machine studies. It can be applied to such machine physics studies as characterization of transverse impedance, observation and identification of coupled-mode instabilities, and electron cloud effects. We developed an FPGA-based bunch-by-bunch tune measurement system that excites a set of driven bunches with a frequency sweep signal, samples a set of monitored bunches, and extracts amplitude and phase information from sampled data using digital demodulation method. We report its hardware and software design, performance, and recent experimental results on the APS storage ring beam.
BNL, Upton, Long Island, New York
Throughout RHIC Run-9 (polarized protons) and Run-10 (gold), numerous modifications to the Baseband Tune (BBQ) system were made. Hardware and software improvements resulted in improved resolution and control, allowing the system to overcome challenges from competing 60 Hz mains harmonics, other spectral content, and other beam issues. Test points from the Analog Front End (AFE) were added and connected to diagnostics that allow us to view signals, such as frequency spectra on a Sr785 dynamic signal analyzer, in real time. Also, additional data can now be logged using a National Instruments DAQ. Development time using tune feedback to obtain full-energy beams at RHIC has been significantly reduced from many ramps over a few weeks, to just a few ramps over several hours. For many years BBQ was an expert-only system, but the many improvements allowed BBQ to finally be handed over to the Operations Staff for routine control.
BNL, Upton, Long Island, New York
AC-dipole magnets are typically implemented as a parallel LC resonant circuit. To maximize efficiency, it’s beneficial to operate at a high Q. This, however, limits the magnet to a narrow frequency range. Current designs therefore deliberately spoil the Q to provide a wider bandwidth at the cost of efficiency. Dynamically tuning the resonant circuit tries to maintain a high efficiency while providing a wide frequency range. The results of ongoing efforts at BNL to implement dynamically tuned high-Q AC dipoles will be presented.
LBNL, Berkeley, California
Stabilized optical fiber links have been under development for several years for high precision transmission of timing signals for remote synchronization of accelerator and laser systems. In our approach, a master clock signal is modulated on an optical carrier over a fiber link. The optical carrier is also used as the reference in a heterodyne interferometer, which is used to precisely measure variations, mainly thermal, in the fiber length. The measured variations are used to correct the phase of the transmitted clock signal. We present experimental results showing sub-10 fsec relative stability of a 200 m link, and sub-20 fsec stability of a 2.2 km link.
LBNL, Berkeley, California
High precision phase measurement is important for many areas of accelerator operation. In a heterodyne digital receiver, one source of phase error is due to the thermal variation of the input stage. We have developed a technique to calibrate this drift. A CW calibration signal is sent through the same components together with the RF signal to measure and compensate the component drift. At intermediate frequency (IF), we use FPGA based digital signal processing to measure and reconstruct the RF signal after applying appropriate correction. Using this technique, we can measure the phase of a 2856 MHz signal with an accuracy of 15 mdeg. We describe how this is approach is applied to the femto-second timing distribution system.
SLAC, Menlo Park, California
The Linac Coherent Light Source requires precision timing trigger signals for various accelerator diagnostics and controls at SLAC-NAL. A new timing system has been developed that meets these requirements. This system is based on COTS hardware with a mixture of custom-designed units. An added challenge has been the requirement that the LCLS Timing System must co-exist and “know” about the existing SLC Timing System. This paper describes the architecture, construction and performance of the LCLS timing event system.
SLAC, Menlo Park, California
The LCLS Undulator Beam Loss Monitor System is required to detect any loss radiation seen by the FEL undulators. The undulator segments consist of permanent magnets which are very sensitive to radiation damage. The operational goal is to keep demagnetization below 0.01% over the life of the LCLS. The BLM system is designed to help achieve this goal by detecting any loss radiation and indicating a fault condition if the radiation level exceeds a certain threshold. Upon reception of this fault signal, the LCLS Machine Protection System takes appropriate action by either halting or rate limiting the beam. The BLM detector consists of a PMT coupled to a Cherenkov radiator located near the upstream end of each undulator segment. There are 33 BLMs in the system, one per segment. The detectors are read out by a dedicated system that is integrated directly into the LCLS MPS. The BLM readout system provides monitoring of radiation levels, computation of integrated doses, detection of radiation excursions beyond set thresholds, fault reporting and control of BLM system functions. This paper describes the design, construction and operational performance of the BLM readout system.
BNL, Upton, Long Island, New York
A new microwave link has been developed for the longitudinal stochastic cooling system, replacing the fiber optic link used for the transmission of the beam signal from the pickup to the kicker. This new link reduces the pickup to kicker delay from 2/3 of a turn to 1/6 of a turn, which greatly improves the phase margin of the system and allows operation at higher frequencies. The microwave link also introduces phase modulation on the transmitted signal due to variations in the local oscillators and time of flight. A phase locked loop tracks a pilot tone generated at a frequency outside the bandwidth of the cooling system. Information from the PLL is used to calculate real-time corrections to the cooling system at a 10 kHz rate. The design of the pilot tone system is discussed and results from commissioning are described.
ELETTRA, Basovizza
The bunch arrival monitor (BAM) for the IV generation synchrotron light source FERMI@Elettra is presented. It is based on an original idea developed at FLASH/DESY, specifically designed and built in-house for FERMI@Elettra. Each BAM station consists of a front-end module, located in the machine tunnel, and of a back-end unit located in the service area. It makes use of the pulsed optical phase reference along with the stabilized fiber link. The front end converts the bunch arrival times into amplitude variations of the optical phase reference pulses distributed over the link. The analogue signal is generated at the e-beam's passage in a broadband pick-up and is sent to the modulation input of an electro-optical modulator (EOM). The back end acquires, synchronously, the amplitude modulated pulses, using a broadband photodiode and a fast analog-to-digital converter. The digitized data is sent to the machine control system for further processing. The dedicated analog-to-digital, conversion processing and communication board, part of the monitor back end, is briefly described. The BAM measurements performed on FERMI@Elettra at 10 Hz are presented.
ORNL, Oak Ridge, Tennessee
Recent improvements to the next generation beam loss monitor analog front end used on the SNS accelerator have proved successful. Particularly in the removal of incident EMI noise sources and the reduction of RF cavity X-Rays and non beam related "loss" signals. The prototype system under development allows the users to view true beam loss integrated as part of the machine protect system. Sucessful measurements of activation during non-beam times have also been made. This paper is an overview of the improved electronics and the results of the ongoing checkout and verification of this system.
Bira, Albuquerque, New Mexico
IUCMB, Bloomington, Indiana
A four-channel magnet-power-supply ramp controller has been designed and deployed at the new ALPHA (Advanced Electron Photon Facility) at the IUCMB (Indiana University Center for Matter and Beams). The first application is a power-supply controller; however, the system is a versatile arbitrary voltage-waveform generator with full DAQ (data acquisition) capabilities that can be used in a variety of beam instrumentation settings. The real-time controller can generate four arbitrary, independently-triggerable ramp profiles. A normalized wave-form array is encoded as a Process Variable array and is uploaded and stored by the real-time controller as required. Each ramp array is clocked out to a 16-bit DAC (Digital to Analog Converter) via a DMA FIFO and built-in FPGA. The duration of the waveform is programmable with a minimum time resolution of 20 usec between profile values. Four bipolar DACs have an output range of ± 10V. Eight digital I/O control bits are allocated for each control channel. Typically, these bits are used to monitor and control the power-supply operational state. The control-system interface uses the EPICS Channel-Access server accessible on Labview RT 2009.
BNL, Upton, Long Island, New York
The NSLS-II Injector System Diagnostics will provide instrumentation in the Linac, Booster, transfer lines and beam dumps for measuring key beam parameters. These instruments will be adequate in providing staged commissioning of NSLS-II injectors, as well as allowing sufficient beam diagnostics for tune-up and top up operations. This paper will summarize the progress and implementation status of the NSLS-II injector system diagnostics.
NSRRC, Hsinchu
Taiwan Photon Source (TPS) is a 3 GeV synchrotron light source which being in construction at NSRRC. Designs of various diagnostics are undergoing and will deploy in future to satisfy stringent requirements of TPS for commissioning, operation, and top-off injection. Design of the diagnostics for beam intensity observation, trajectory and beam positions measurement, destructive profile measurement, synchrotron radiation monitors, beam loss monitors, orbit and bunch-by-bunch feedbacks, filling pattern, etc. are in final design phase. Details of current status and implementation of the planned beam instrumentation system for the TPS will summary in this report.
NSRRC, Hsinchu
Diagnostics of the 1.5 GeV Taiwan Light Source (TLS) has been continue upgraded since it operation started in 1993. BPM electronics and orbit feedback system have been upgrade in 2008. Commercial photon BPM electronics was tested recently. The bunch-by-bunch feedback have been deployed to improve beam stability. These upgrades are contributed to improve beam quality a lots. These efforts will be addressed also.
BNL, Upton, Long Island, New York
Slow variations of the RHIC closed orbit have been strongly influenced by diurnal variations. These variations affect the reproducibility of RHIC operation and might have contributed to proton beam polarization degradation during past polarized proton runs. We have developed and commissioned a slow orbit feedback system in RHIC Run-10 to diminish these variations and improve energy ramp commissioning and tuning efficiency. This orbit feedback uses multiple dipole correctors and orbit data from an existing beam position monitor system. The precision of the orbit feedback system has resulted directly from application of an improved algorithm for measurement of the average orbit, from improved survey offsets and various measures taken to ensure deterministic delivery of the BPM data. Closed orbit corrections are calculated with an online model-based SVD algorithm, and applied by a control loop operating at up to 1 Hz rate. We report on the feedback design and implementation, and commissioning and operational experience in RHIC Run-10.
LBNL, Berkeley, California
A hardware system that acquires and stores a large buffer of bunch-by-bunch 16-bit data has been realized. A high resolution (up to 16-bit) analog-to-digital converter (ADC), or bank of ADCs, samples the analog signal at the bunch frequency. The digitized data is fed into a Field Programmable Gate Array (FPGA), which contains an interface to a bank of double data rate (DDR) SDRAM type memory. With appropriate data bus widths, the FPGA bursts the ADC data into the DDR SDRAM fast enough to keep up with the bunch-by-bunch ADC data continuously. The realized system demonstrates continuous data transfer at a rate of 1 GByte/sec, or 16-bit data at 500 MHz, into a 64MByte SDRAM. This paper discusses the implementation of this system and the future of this architecture for bunch-by-bunch diagnostics.
Agilent Technologies SA, Plan-les-Ouates
Agilent Technologies Inc., Loveland
Digital data acquisition in real time applications falls into two categories: digitizing a stream of data without missing a single sample point, and capturing a stream of triggered events without missing a single trigger. Maintaining these data streams over long periods requires an optimized combination of analog signal conditioning, and precise digitization, digital data reduction and high-speed data transfer. This paper describes suggested methods to reduce the amount of measurement data required, reduce the amount of that data that is to be transferred (to a measurement where possible), and then transfer this reduced data in the most rapid fashion. Our approach uses a combination of hardware, firmware and software elements that are designed to work together, optimizing performance and managing the data bottlenecks. New hardware standards and architectures are discussed that improve the capabilities of today's technologies, providing access to higher data and measurement flux. Applications presented in this paper include high trigger rate capture for beam steering and fill pattern monitoring in charged particle accelerators.
LANL, Los Alamos, New Mexico
In a nutshell, the role of a beam diagnostic measurement is to provide information needed to get a particle beam from Point A (injection point) to Point B (a target) in a useable condition, meaning with the right energy and size and with acceptable losses. Specifications and performance requirements of diagnostics are based on the physics of the particle beam to be measured, with typical customers of beam parameter measurements being the accelerator operators and accelerator physicists. This tutorial will be a physics-oriented discussion of the interplay between tuning evolutions and the beam diagnostics systems that support the machine tune. This will include the differences between developing a tune and maintaining a tune, among other things. Practical longitudinal and transverse tuning issues and techniques from a variety of proton and electron machines will also be discussed.
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.