BNL, Upton, Long Island, New York
The Faraday Cup Award is given for an outstanding contribution to the development of an innovative particle beam diagnostic instrument of proven workability. It is presented at the Beam Instrumentation Workshop (BIW), a biennial forum for in-depth discussions of techniques for measuring particle beams produced in accelerators. This session will present the latest Faraday Cup winner, and the Proceedings article associated with it will summarize the history of the award. After the award is presented, this year's honoree (a secret until the Workshop) will give a talk on the design and performance of the winning instrument. For more information on the Award, see http://www.faraday-cup.com.
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.
CERN, Geneva
The diamond beam monitor is a solid-state ionization chamber that stands out due to its fast and efficient charge collection and its high radiation tolerance. The diamond technology gives a charge collection time of less than 1 ns and lifetime studies made at CERN with 24 GeV protons showed a decrease in performance of only 50% at 10 MGy, which make this device particularly well adapted to applications in particle accelerators. A poly-crystalline CVD diamond beam monitor has been evaluated as a beam halo loss monitor for the CERN LHC accelerator. Despite the read-out being made through 250 m of cable, the tests showed a good signal-to-noise ratio of 6.8, an excellent double-pulse resolution of less than 5 ns and a high dynamic range basically unlimited except by the electronics. A single-crystalline CVD diamond beam monitor was built and tested in cooperation with Bergoz Instrumentation for ISOLDE at CERN for the HIE-REX upgrade. This device was used to measure the beam intensity for particle counting and for measuring the beam energy spectrum. An energy resolution of 0.6% and a time resolution of 39 ps were measured for a carbon ion energy of 22.8 MeV.
BNL, Upton, Long Island, New York
A residual gas x-ray beam position monitor (RGXBPM) was developed for PETRA-III storage ring. This type of x-ray beam position monitors (XBMP) tend to overcome some deficiencies of the blade type XBPMs, which are currently employed at the third generation synchrotron facilities as "white" undulator beam XBPMs. While blade XBPMs provide micron-accuracy resolution, the signal depends on the undulator gap and is also affected by stray radiation from bending magnets and focusing optics. The residual gas XBPM detects position of the centre of gravity of the undulator radiation; it has no elements that are hit by the x-ray beam, and complies with the windowless concept of the PETRA-III beamlines. Residual gas beam profile monitors were first developed to provide beam profile measurements at charged particles accelerators. The spatial resolution of RGXBPM was substantially improved in order to comply with the requirements at the PETRA III storage ring. Due to limited space, a thorough electrostatic optimization of RGXBPM was needed to achieve required electrical field quality. Test results obtained at the ESRF and commissioning of the RGXBPMs at PETRA-III will be reported.
Tohoku University, School of Scinece, Sendai
Generation of high brilliance beam using an RF gun is very attractive for advanced use of electron linacs. Beam dynamics in the RF gun has been studied theoretically so far, and many simulation codes have been developed. The stage in which the beam is extracted and accelerated to relativistic momentum is crucial for understanding of space charge dominated beams. In this sense, actual measurement of the beam phase space is highly desired to examine the validity of the simulation codes. However, for the low energy electrons, such measurement is difficult because the phase space is easily distorted due to space charge effect during travel through drift space. Accordingly, we have considered employing the energy dependent angular distribution of Cherenkov radiation. Though the emission angle of Cherenkov radiation decreases rapidly with increasing beam energy, it is still 25 deg/MeV at an energy around 2 MeV when we use a radiator that has a refractive index of 1.035. Thus the energy distribution can be measured by observing the Cherenkov ring with sufficient angular resolution. Since this method needs only a thin radiator, the drift space length can be minimized.
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.
UniDo/IBS, Dortmund
iThemba LABS, Somerset West
FZJ, Jülich
DELTA, Dortmund
The interaction of an ion beam with the residual gas might lead to a photon emission of the excited residual gas molecule. These photons can be used to monitor the beam profile. Therefore a multichannel photomultiplier is used together with an optical system. Measurements at the COSY synchrotron are presented. The usability of the method is discussed by comparing to measurements at the iThemba Labs beam line and the JESSICA experiment, a spallation source prearrangement at COSY.
GSI, Darmstadt
Technical University Darmstadt, Darmstadt
TU Darmstadt, Darmstadt
Scintillating screens are widely used for transverse beam profile monitoring and pepper-pot emittance measuring instruments at accelerator facilities. For high current beam operations at the GSI heavy ion UNILAC, several inorganic scintillators were investigated under different ion beam conditions in the energy range from 4.8 to 11.4 MeV/u and currents up to some mA. The imaging properties of various scintillating screens were studied with respect to light yield and imaged beam width, i.e. important parameters for precise beam profile measurements. The measured light yield and beam width show a strong dependence on the scintillating material and change significantly with screen temperature. The spectral response of the materials was mapped for different temperature levels, using a spectrometer in the visible and near UV range. The results clearly demonstrate that the scintillating properties of the materials, and their temperature, are critical issues for high current operations and have to be taken into account for correct beam profile reading.
BNL, Upton, Long Island, New York
Modes with transverse electric field (TE-modes) in the NSLS-II multipole vacuum chamber can be generated at frequencies above 450 MHz due to its geometric dimensions. Since the NSLS-II BPM system is triggered by the RF at 500 MHz, frequencies of higher-order modes (HOMs) can be generated within the transmission band of the band pass filter. In order to avoid systematic errors in the NSLS-II BPM system, we introduced frequency shift of HOMs by using RF metal shielding located in the antechamber slot.
ANL, Argonne
For reliable radiation dosimetry of undulator magnets, a beam loss monitor (BLM) covering a large solid angle from the point of beam losses is highly desirable. A BLM that uses a Cherenkov radiator plate wrapping around the beam pipe is utilized in the Linac Coherent Light Source (LCLS) undulator systems, and a similar BLM geometry is currently being tested for the Advanced Photon Source (APS) undulators. We report on measurements made with large solid-angle BLMs recently installed in the APS storage ring (SR) and the booster-to-SR transfer line (BTS) to assess the following design and performance characteristics: (1) relative sensitivity of the Cherenkov detector as a function of the transverse position of electron entry into the quartz radiator; (2) signal intensity as a function of the detector distance from the nominal beam loss location at the undulator vacuum chamber entrance; and (3) the effect of incorporating different tungsten/lead enhancers upstream of the radiator. The measured data will be compared with numerical simulation of the beam loss processes.
ANL, Argonne
Accurate and stable x-ray beam position monitors (XBPMs) are key elements in a feedback system for obtaining desired x-ray beam stability. For the low-emittance mode of operation of the APS, the cross sections of the undulator x-ray beams are not upright ellipses, and the effective beam sizes in the horizontal and vertical planes depend on the undulator gaps. These beam characteristics introduce strong gap dependence in blade-type XBPMs designed for upright elliptical beams. A center-of-mass detector XBPM will significantly reduce the gap dependence of the BPM readings. We report the development status of a high-power center-of-mass XBPM at the APS. We note that users often discard more than 50% of the undulator beam power outside of the monochromatic beam. These photons can be intercepted by the limiting aperture of the beamline, and then the x-ray fluorescence footprint can be imaged onto a detector. The position of the x-ray beam can be read out using position-sensitive silicon photodiodes. Thermal analyses show that the XBPM can be used for the measurement of beam with a total power up to 20 kW for the 7-GeV / 200-mA operation of a 5-m undulator in the APS.
NewPath, Salt Lake City, Utah
Others have shown that the voltages induced on one uniformly-wound toroidal coil and two sinusoidally-wound toroidal coils may be used to determine the current in a single filament and its coordinates. We have extended this technique to show that the voltages measured on a group of sinusoidally-wound toroidal coils may be used to approximate the distribution of current within their common aperture. This is possible because each measured voltage is proportional to the product of unique functions of the radial and azimuthal coordinates of each increment of the current [1,2]. We have developed matrix methods to determine the transverse distribution of the current and determined the sensitivity of these calculations to measurement errors. Shielded sinusoidally-wound coils with a precision of 0.02 cm have been prepared using rapid prototyping, and methods have been defined to prepare the next generation of these coils, which will have a precision of 0.001 cm, by using an engraving tool with the 4th axis of a vertical milling machine.
RIKEN/SPring-8, Hyogo
Hamamatsu Photonics K.K., Hamamatsu-city
JASRI/SPring-8, Hyogo-ken
The SCSS test accelerator, which was constructed to check feasibility of XFEL/SPring-8, is operated for user experiments using stable EUV SASE. This accelerator provides a high quality electron beam with parameters suitable for power saturation of the EUV SASE, such as a bunch length of 300 fs and a peak current of 700 A. Evaluating the parameters is very important to ensure the stable generation of the SASE. The bunch length measurement systems to evaluate the parameters have been developed. The systems use the rf zero phasing method, the EO sampling method with temporal decoding and an 800 nm laser, and the method of observing OTR (near infrared region) by a FESCA-200 streak camera, which are mature technologies. All the measured bunch lengths were about 300 fs (FWHM), which is consistent with the individual methods. The most important result is that the streak camera with optimum tuning directly measured the temporal structure with femtosecond resolution. This presentation briefly introduces a development plan for a higher-resolution streak camera and a beam monitor system for the XFEL, as well as the experimental set-up and results.
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.
LBNL, Berkeley, California
Laboratory high energy density experiments using ion beam drivers rely upon the delivery of high-current, high-brightness ion beams with high peak intensity onto planar targets. Solid-state optical scintillators are typically used to measure the ion beam spatial profile but they display dose-dependent degradation and aging effects. These effects produce uncertainties and limit the accuracy of measuring peak beam intensities delivered to the target. For beam tuning and benchmarking the incident beam intensity, we have developed a cross-calibrating diagnostic suite that both places a lower limit on intensity and extends the upper limit of measurable peak intensity dynamic range. Absolute intensity calibration is obtained with a 3 um thick tungsten foil calorimeter. We present experimental evidence for peak intensity measures in excess of 200 kW/cm2 using a 300 kV, 25 mA, 5-20 usec K+ beam driver. Radiative models and thermal diffusion effects are discussed as they affect temporal and spatial resolution of beam intensity profiles.
BNL, Upton, Long Island, New York
A synchrotron light diagnostic beamline has been designed at the NSLS-II storage ring, using the dipole radiations. A "cold-finger" configuration has been selected to block the central x-rays. Beam power on the first mirror is less than 1 W, so no water cooling was required for this in-vacuum mirrors. The beamline layout and major applications will be discussed in this paper. Two vacuum ports are reserved in the NSLS2 booster ring to monitor the transverse profile as well as bunch length measurement during ramping. There will be a synchrotron light port in the BTS transport line for observing the injecting beam behavior during top-up operation.
PSI, Villigen
JLAB, Newport News, Virginia
Electro Optical (EO) sampling is a promising non-destructive method for measuring ultra short (sub-ps) electron bunches. The FEMTO slicing experiment at the Swiss Light Source modulates about 1 pC of the 4-nC electron bunch longitudinally. The coherent synchrotron radiation (CSR) emitted by this substructure was sampled by 100 fs long pulses from an Yb fiber laser in EO crystals of different materials (GaP, ZnTe). The broadening of this ps long structure over several turns of the synchrotron could be measured with sub-ps resolution.
Cockcroft Institute, Warrington, Cheshire
The University of Liverpool, Liverpool
DITANET is the largest-ever EU funded training network in beam diagnostics. The network members – universities, research centres and industry partners – are developing diagnostics methods for a wide range of existing or future particle accelerators, both for electron and for ion beams. This is achieved through a cohesive approach that allows for the exploitation of synergies, whilst promoting knowledge exchange between partners. In addition to its broad research program, the network organizes schools and topical workshops for the beam instrumentation community. This contribution gives an overview of the Network's research portfolio, summarizes the main research results from the first two years of DITANET and presents past and future training activities.
ORNL, Oak Ridge, Tennessee
Beam Loss Monitors are common devices used in hadron and lepton accelerators. Depending on accelerator specifics, BLMs could be just diagnostics or could play an essential role in the Machine Protection System (MPS). This tutorial discusses different types of BLMs and their applicability to different accelerators. It covers traditional BLMs like ionization chambers and scintillator-based devices, and also less common techniques like those based on fiber optics and avalanche diodes. The tutorial gives an overview of the underlying physics involved in beam loss detection, and recent advances in computer simulation of particle interaction with matter helpful for BLM modeling. Options for signal processing electronics are described, as well as interfaces to both the control system and the MPS.
PSI, Villigen
The 9th European Workshop on Beam Diagnostics and Instrumentation for Particle Accelerators (DIPAC 2009) was hosted by Paul Scherrer Institute (PSI) and took place at the Hotel Mercure Conference Center in Basel, Switzerland, May 25-27, 2009. A record number of 210 registered participants contributed to an exciting scientific program with ten invited talks, fourteen contributed orals and 115 poster contributions. In this talk, I will provide an overview of the various fields of beam instrumentation discussed during the workshop. A number of highlights from the scientific program have been selected, illustrating some of the outstanding achievements in accelerator diagnostics, presented at DIPAC 2009.