A.J. Halama, V. Kamerdzhiev, G.R. Rupsch
GSI, Darmstadt, Germany
The High Energy Storage Ring (HESR), within the FAIR project, will according to current planning provide anti-proton beams for PANDA and heavy ion beams for a.o. SPARC. With the beam instrumentation devices envisaged in larger quantities, e.g. BPM and BLM, testing is well underway. Other beam instrumentation instruments like Viewer are in late production stage, Scraper is being tested and for the IPM the 1st of series production has started. An overview of the status of the work package beam instrumentation will be presented as well as test bench results of already produced instruments.
R. Dölling, F. Marcellini, M. Sapinski
PSI, Villigen PSI, Switzerland
A new generation of monitor plugs is under develop-ment as spares for the ageing wire profile monitors and beam position monitors inserted into massive shielding in the target regions of the 590 MeV proton beam line at HIPA. A prototype was installed recently in the beam line to the ultra-cold neutron source UCN, to test the perfor-mance of wire monitor, BPM and modular mechanical design in a low-radiation environment. We report on first measurements with beam.
L.T. Stant, M.G. Abbott, L. Bobb, G. Cook, L. Hudson, A.F.D. Morgan, E.P.J. Perez Juarez, A.J. Rose, A. Tipper
DLS, Oxfordshire, United Kingdom
The UK national synchrotron facility, Diamond Light Source, is preparing for a major upgrade to the accelerator complex. Improved beam stability requirements necessitate the fast orbit feedback system be driven from beam position monitors with lower noise and drift performance than the existing solution. Short-term beam motion must be less than 2 nm/sqrt(Hz) over a period of one second with a data rate of 100 kHz, and long-term peak-to-peak beam motion must be less than 1 µm. A new beam position monitor is under development which utilises the pilot-tone correction method to reduce front-end and cabling perturbations to the button signal; and a MicroTCA platform for digital signal processing to provide the required data streams. This paper discusses the challenges faced during the design of the new system and presents experimental results from testing on the existing machine.
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S.M. Gibson, A. Arteche
Royal Holloway, University of London, Surrey, United Kingdom
T. Lefèvre, T.E. Levens
CERN, Meyrin, Switzerland
An Electro-Optic Beam Position Monitor (EO-BPM) is being developed as a high-frequency (up to 10 GHz) diagnostic for crabbing and Head-Tail intra-bunch detection at the HL-LHC. Following an earlier prototype at the SPS that demonstrated single-pickup signals, an upgraded design of an interferometric EO-BPM has been beam-tested at the HiRadMat facility for validation and characterisation studies. In the new design, the fibre-coupled Mach-Zehnder interferometer arms are modulated by lithium niobate waveguides integrated in an upgraded opto-mechanical arrangement that has been developed to produce a highly magnified image field replica of the passing Coulomb field. A new detection technique that is directly sensitive to the interferometric optical difference signal from opposite EO buttons has been applied to measure single-shot bunches for the first time. A transverse resolution study over a ±20 mm range at 3 GHz bandwidth produced the first successful electro-optic bunch-by-bunch position measurement at the HiRadMat in-air extraction line. The results of this campaign show promise for an in-vacuum design that is in production for beam tests at the SPS during Run-3 of the LHC.
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The beam quadrupole moment of stored beams can be measured with a four-plate quadrupole pick-up. The frequency spectrum of the quadrupole moment contains not only the usual first-order dipole modes (the betatron tunes) but also the second-order coherent modes, comprising of (1.) (even) normal envelope modes, (2.) odd (skew) envelope modes and (3.) dispersion modes. As a novel diagnostic tool, the measured frequencies and amplitudes provide direct access to transverse space charge strength through the tune shift as well as linear coupling (and mismatch thereof), along with the benefit of a non-invasive beam-based measurement. Technically, quadrupole moment measurements require a pick-up with non-linear position sensitivity function. We discuss recent developments and depict measurements at the GSI SIS18 heavy-ion synchrotron.
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M. Repovž, M. Cerv, C. Kurfürst, G. Muyan, S. Myalski, A. Pozenel, C. Schmitzer, M. Wolf
EBG MedAustron, Wr. Neustadt, Austria
A. Bardorfer, B. Baričevič, P. Paglovec, M. Škabar
I-Tech, Solkan, Slovenia
The MedAustron Ion Therapy Centre is a synchrotron-based particle therapy facility which delivers proton and carbon beams for clinical treatment. Currently, the facility treats roughly 40 patients per day and is improving its systems and workflows to further increase this number. MedAustron was commissioned and is operational without fully integrated systems for measurements of ’time of flight’ (beam energy) in the MEBT and beam position in the LINAC. This paper presents the newly developed system for these use cases, which will improve the overall commissioning and QA accuracy. It will unify the hardware used for the cavity regulation in the injector LLRF and the synchrotron LLRF. It will also be used for SYNC pickups, Schottky monitors and RF knock-out exciter. The new system is based on the CotS MicroTCA platform, which is controlled by the MedAustron Control System based on NI-PXIe. Currently it supports fiber-optic links (SFP+), but other links (e.g. EPICS, DOOCS) can be established. The modular implementation allows for connections to other components, such as motors, amplifiers, or interlock systems and will increase the robustness and maintainability of the accelerator.
A bunched beam intensity measurement system for the CERN Extra Low ENergy Antiproton (ELENA) ring, using a cylindrical shoe-box electrostatic pick-up from the existing orbit system [1], is presented. The system has been developed to measure very challenging beam cur-rents, as low as 200nA corresponding to intensities of the order of 107 antiprotons circulating with a relativistic beta of the order of 10-2. In this work we derive and show that the turn-by-turn beam intensity is proportional to the baseline of the sum signal and that, despite the AC-coupling of the system, the installed front-end electronics, based on a charge amplifier, not only guarantees the preservation of the bunch shape (up to a few tens of MHz), but also allows for an absolute calibration of the system. In addition, the linearity of the intensity measurements and their inde-pendence with respect to average beam position is evalu-ated using a standard electromagnetic simulation tool. Finally, experimental measurements throughout typical antiproton deceleration cycles are presented and their accuracy and precision are discussed.
H. Maesaka, T. Inagaki
RIKEN SPring-8 Center, Hyogo, Japan
H. Dewa, T. Inagaki, H. Maesaka, K. Yanagida
JASRI, Hyogo, Japan
K. Ueshima
QST, Sendai, Miyagi, Japan
We developed a differential current transformer (CT) for electron beam charge measurement in noisy environments, such as near high-power pulse sources. This CT has four pickup wires coiled at equal intervals (90 deg.) on a toroidal core and each coil is wound for two turns. The midpoint of the coil is connected to the body ground so that a balanced differential signal is generated at both ends. A beam pipe with a ceramics insulation gap is inserted into the toroidal core to obtain a signal from a charged-particle beam. The four pairs of signals are transmitted through a CAT6 differential cable and fed into differential amplifiers. The common-mode noise from the noisy ground at the CT is canceled out by the amplifier. The four signals are then summed and digitized by an AD converter. We produced differential CTs and installed them into the new injector linac of NewSUBARU (*). Before the installation, the frequency response was measured in a laboratory and a flat response of up to 100 MHz was obtained as expected. Common-mode noise cancellation was also confirmed at NewSUBARU and the CTs have been utilized for beam charge monitoring stably. *: T. Inagaki et al., ’Construction of a Compact Electron Injector Using a Gridded RF Thermionic Gun and a C-Band Accelerator’, in Proc. IPAC’21, pp. 2687-2689. doi:10.18429/JACoW-IPAC2021-WEPAB039
M. Krupa, I. Degl’Innocenti, D. Gudkov, G. Schneider
CERN, Meyrin, Switzerland
D.R. Bett
JAI, Oxford, United Kingdom
The demanding instrumentation requirements of the future High Luminosity LHC (HL-LHC) require 44 newly designed Beam Position Monitors (BPM) to be installed around the ATLAS and CMS experiments in 2026-2028. Three BPM types are now in pre-series production, with two more variants under design. Close to the collision point, a set of cryogenic directive coupler BPMs equipped with a brand new acquisition system based on nearly-direct digitization will resolve the position of the two counter-rotating LHC beams occupying a common vacuum chamber. Other new button and stripline BPMs will provide not only the transverse beam position, but also timing signals for the experiments, and diagnostics for the new HL-LHC crab cavities. This contribution summarizes the HL-LHC BPM specifications, gives an overview of the new BPM designs, reports on the pre-series BPM production status and plans for series manufacturing, outlines the foreseen acquisition system architecture, and highlights the first beam measurements carried out with the proof-of-concept electronics for the directive stripline BPMs.
Modeling and Experimental Evaluation of a Bunch Arrival-Time Monitor with Rod-Shaped Pickups and a Low-Pi-Voltage Ultra-Wideband Traveling Wave Electro-Optic Modulator for X-Ray Free-Electron Lasers
K. Kuzmin, E. Bründermann, A.-S. Müller, G. Niehues
KIT, Karlsruhe, Germany
W. Ackermann, H. De Gersem
TEMF, TU Darmstadt, Darmstadt, Germany
M.K. Czwalinna, H. Schlarb
DESY, Hamburg, Germany
C. Eschenbaum, C. Koos, A. Kotz, A. Schwarzenberger
IPQ KIT, Karlsruhe, Germany
A. Penirschke, B.E.J. Scheible
THM, Friedberg, Germany
X-ray Free-Electron Laser (XFEL) facilities, such as the 3.4-km European XFEL, use all-optical links with electro-optic bunch arrival-time monitors (BAM) for a long-range synchronization. The current BAM systems achieve a resolution of 3.5 fs for 250 pC bunches. Precise bunch arrival timing is essential for experiments, which study ultra-fast dynamical phenomena with highest temporal resolution. These experiments will crucially rely on femtosecond pulses from bunch charges well below 20 pC. The state-of-the-art BAMs are not allowing accurate timing for operation with such low bunch charges. Here we report on the progress in development of an advanced BAM (system) based on rod-shaped pickups mounted on a printed circuit board and ultra-wideband travelling-wave electro-optic modulators with low operating voltages. We perform modeling and experimental evaluation for the fabricated pickups and electro-optic modulators and analytically estimate timing jitter for the advanced BAM system. We discuss an experimental setup to demonstrate joint operation of new pickups and wideband EO modulators for low bunch charges less than 5 pC.
L. Crescimbeni, D.M. Haider, M. Schwickert, T. Sieber, T. Stöhlker
GSI, Darmstadt, Germany
F. Machalett, T. Stöhlker
IOQ, Jena, Germany
M. Schmelz, T. Schönau, R. Stolz, V. Zakosarenko
IPHT, Jena, Germany
F. Schmidl, T. Schönau, P. Seidel
FSU Jena, Jena, Germany
V. Zakosarenko
Supracon AG, Jena, Germany
Funding:Supported by the BMBF, project number 05P21SJRB1. Cryogenic Current Comparators (CCC) are presently used at CERN-AD (100 mm beamline diameter) and in the FAIR project at CRYRING (150 mm beamline diameter) for non-destructive absolute measurement of beam currents below 20 ’A (current resolution 10 nA). Both sensor versions (CERN-Nb-CCC and FAIR-Nb-CCC-XD) use niobium as superconductor for the DC-transformer and magnetic shielding. The integrated flux concentrators have an inductance of below 100 ’H at 4.2 Kelvin. The new Sm-series (smart & small) is designed for a beamline diameter of 63 mm and uses lead for the superconducting shield. The first sensor (IFK-Pb-DCCC-Sm-200) has two core-based pickup coils (2x 100 µH at 4.2 K) and two SQUID units, to eliminate Barkhausen current jumps as part of the low frequency 1/f-noise. During the construction some basic experiments on noise behavior (fluctuation’dissipation theorem, white noise below 2 pA/sqrt(Hz)) and magnetic shielding (flux concentrator and shielding as LC circuit resonance , additional mu-metal shielding) were undertaken, the results of which are presented here. Finally, a current resolution of 500 pA could be achieved in the laboratory.
