Diagnostics
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Abstract: Beam instrumentation is of critical importance for the operation and optimization of modern particle accelerators. With advancing accelerator technology and the increasing requirements for higher quality beams, it is an ever-present challenge that beam diagnostics must similarly progress. In this talk the instrumentation considered most impactful for the progress of 4th generation storage ring light sources is presented with reference to possible lessons learned, applicability to other accelerators and potential future directions.
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May 2024
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I22-Small angle scattering & Diffraction
Detectors
Diagnostics
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Open Access
Abstract: Single-crystal chemical vapour deposition (CVD) diamond detectors are an established transmissive synchrotron beamline diagnostic instrument used for beam position and beam intensity monitoring. A recently commercialized alternative is silicon carbide (4H-SiC) devices. These have the potential to provide the same diagnostic information as commercially available single-crystal CVD diamond X-ray beam position monitors, but with a much larger transmissive aperture. At Diamond Light Source an experimental comparison of the performance of single-crystal CVD diamond and 4H-SiC X-ray beam position monitors has been carried out. A quantitative comparison of their performance is presented in this paper. The single-crystal diamond and 4H-SiC beam position monitors were installed in-line along the synchrotron X-ray beam path enabling synchronous measurements at kilohertz rates of the beam motion from both devices. The results of several tests of the two position monitors' performance are presented: comparing signal uniformity across the surface of the detectors, comparing kHz intensity measurements, and comparing kHz beam position measurements from the detectors. Each test is performed with a range of applied external bias voltages. A discussion of the benefits and limitations of 4H-SiC and single-crystal CVD diamond detectors is included.
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Sep 2023
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Diagnostics
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Open Access
Abstract: X-ray pinhole cameras are employed to provide the transverse profile of the electron beam from which the emittance, coupling and energy spread are calculated in the storage ring of Diamond Light Source. Tungsten blades separated by shims are commonly used to form the pinhole aperture. However, this approach introduces uncertainties regarding the aperture size. X-ray lithography, electroplating and moulding, known as LIGA, has been used to provide thin screens with well-defined and high aspect ratio pinhole apertures. Thus, the optimal aperture size given the beam spectrum can be used to improve the spatial resolution of the pinhole camera. Experimental results using a LIGA screen of different aperture sizes have been compared to SRW-Python simulations over the 15-35 keV photon energy range. Good agreement has been demonstrated between the experimental and the simulation data. Challenges and considerations for this method are also presented.
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Nov 2022
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Diagnostics
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Open Access
Abstract: Tungsten blade based photoemission X-ray Beam Position Monitors (XBPMs) are widely used as white beam diagnostics at synchrotrons. Traditionally, the scale factors are determined by stepper motor movements of the XBPM, or by controlled electron beam displacements, and measuring the response. These measurements must be repeated for each ID gap to produce a complete set of scale factors for all operational conditions. This calibration procedure takes time and cannot be done while users are acquiring data. In addition, the scale factors can vary over time due to changes to the storage ring. It is possible for these scale factors to become inaccurate, reducing the accuracy of the beam position measured by the XBPMs. By using the intrinsic kHz electron beam movements and correlating the signals from electron beam position monitors and XBPMs it is possible to have a real-time calculation of the scale factors without the need to disturb user operation. Presented in this paper is a method to non-invasively calculate scale factors during normal user operation. A comparison of the precision of this method versus the traditional stepper motor method is presented
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Oct 2022
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Diagnostics
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Open Access
Abstract: As synchrotron beamlines increasingly use micro-focus techniques with detectors sampling at kHz rates, the need for real-time monitoring of the beam position at similar bandwidths is vital. Commercially available single-crystal CVD diamond X-ray diagnostics are well established as excellent non-destructive monitors for synchrotron X-ray beamlines. Silicon carbide (4H-SiC) X-ray beam position monitors (XBPMs) are a recent development with the potential to provide the same benefits as their diamond counterparts with larger usable apertures and lower cost. At Diamond Light Source a comparison between single-crystal CVD diamond and 4H-SiC XBPMs has been carried out. The sc-diamond and 4H-SiC beam position monitors are mounted in-line along the beam path, so that synchronous kHz measurements of the synchrotron X-ray beam motion can be measured. Several tests of the two position monitors performance are presented: comparing kHz beam position measurements from the detectors, temporal response, and signal uniformity across the face of the detectors. Each test is performed with varying bias voltages applied to the detectors. A discussion of the benefits and limitations of 4H-SiC and diamond detectors is included.
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Oct 2021
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Detectors
Diagnostics
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Open Access
Abstract: A new feedback system is being developed at Diamond Light Source, applying a modulation to the position of the electron beam to keep the synchrotron X-ray beam fixed at the sample-point. Beamline detectors operating in the 100-1000Hz regime are becoming common, and the X-ray beam stability demanded by beamlines is thus of comparable bandwidths. In this paper we present a feedback system operating at these bandwidths, using a diagnostic instrument permanently installed in the X-ray beam path to measure the error in beam position at the sample point, and fast air-cored magnets to apply a small modulation to the electron beam to compensate. Four magnets are used to generate electron beam bumps through an ID straight. This modulation of the beam away from the nominal orbit is small, less than 10 microns, but should be sufficient to compensate for the bulk of the X-ray motion observed at the sample. It is small enough that the impact on the machine will be negligible. This system aims to maintain X-ray beam stability to within 3% of a beam size, at bandwidths of up to 500Hz.
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Nov 2019
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Diagnostics
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D.
Alves
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A.
Curcio
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R. O.
Jones
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R.
Kieffer
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T.
Lefèvre
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S.
Mazzoni
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N.
Mounet
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E.
Senes
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A.
Schloegelhofer
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K.
Fedorov
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P.
Karataev
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D.
Harryman
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K.
Lekomtsev
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V. V.
Bleko
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S. Y.
Gogolev
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A. S.
Konkov
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J. S.
Markova
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A. P.
Potylitsyn
,
D. A.
Shkitov
,
M.
Billing
,
J.
Conway
,
Y. Padilla
Fuentes
,
J.
Shanks
,
M.
Apollonio
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L.
Bobb
,
A.
Aryshev
,
J.
Gardelle
,
K.
Lasocha
Open Access
Abstract: Over the past 3 years, the emission of Cherenkov Diffraction Radiation (ChDR), appearing when a relativistic charged particle moves in the vicinity of a dielectric medium, has been investigated as a possible tool for non-invasive beam diagnostics. ChDR has very interesting properties, among which is the emission of a large number of photons in a narrow and well-defined solid angle which provides excellent conditions for signal detection with very little background. This contribution will present a collection of recent beam measurement results performed at several facilities such as the Cornell Electron Storage Ring (CESR), the Ad- vanced Test Facility 2 (ATF2) at KEK and the CLEAR test facility at CERN. These results, complemented by simulations, are showing that both the incoherent and coherent emission of Cherenkov Diffraction radiation could open the path for a new kind of beam diagnostic technique for relativistic charged particle beams.
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Sep 2019
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Diagnostics
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Open Access
Abstract: Resonant Spin Depolarization (RSD) is a well-known technique that has been employed by Diamond Light Source (DLS) for beam energy measurements. In this project, we study a new approach to make RSD compatible with user beam operation and provide a continuously updated online measurement. An array of four custom-made scintillation detectors has been installed around the beam pipe, downstream of collimators to capture the highest fraction of lost particles and maximize the count rate. The excitation is gated to half of the stored bunches and the acquisition system counts losses in both halves independently. Using the count in the un-excited part for normalisation suppresses external factors that modify the loss rate. Different parameters of the measurement, like excitation kick strength and duration have been explored to optimise depolarisation and to increase the reliability of the measurement.
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Jan 2019
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Diagnostics
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R.
Kieffer
,
L.
Bartnik
,
M.
Bergamaschi
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V. v.
Bleko
,
M.
Billing
,
L.
Bobb
,
J.
Conway
,
M.
Forster
,
P.
Karataev
,
A. s.
Konkov
,
R. o.
Jones
,
T.
Lefevre
,
J. s.
Markova
,
S.
Mazzoni
,
Y.
Padilla Fuentes
,
A. p.
Potylitsyn
,
J.
Shanks
,
S.
Wang
Open Access
Abstract: We report on the observation of incoherent Cherenkov radiation emitted by a 5.3 GeV positron beam circulating in the Cornell electron-positron storage ring as the beam passes in the close vicinity of the surface of a fused silica radiator (i.e., at a distance larger than 0.8 mm). The shape of the radiator was designed in order to send the Cherenkov photons towards the detector, consisting of a compact optical system equipped with an intensified camera. The optical system allows both the measurements of 2D images and angular distribution including polarization study. The corresponding light intensity has been measured as a function of the distance between the beam and the surface of the radiator and has shown a good agreement with theoretical predictions. For highly relativistic particles, a large amount of incoherent radiation is produced in a wide spectral range. A light yield of 0.8×10−3 photon per particle per turn has been measured at a wavelength of 600±10 nm in a 2 cm long radiator and for an impact parameter of 1 mm. This will find applications in accelerators as noninvasive beam diagnostics for both leptons and hadrons.
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Aug 2018
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Diagnostics
Magnets
Mechanical Engineering
Optics
Vacuum
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R.
Bartolini
,
C.
Abraham
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M.
Apollonio
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C. P.
Bailey
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M. P.
Cox
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A.
Day
,
R. T.
Fielder
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N. P.
Hammond
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M. T.
Heron
,
R.
Holdsworth
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J.
Kay
,
I. P. S.
Martin
,
S.
Mhaskar
,
A.
Miller
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T.
Pulampong
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G.
Rehm
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E. C. M.
Rial
,
A.
Rose
,
A.
Shahveh
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B.
Singh
,
A.
Thomson
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R. P.
Walker
Open Access
Abstract: Diamond has recently successfully commissioned a major change in the lattice consisting of the substitution of a standard double-bend achromat (DBA) cell with a modified four-bend achromat (4BA) cell called “double-double bend achromat” (DDBA). This work stems from the original studies initiated in 2012 towards a Diamond upgrade and provides the benefit of an additional straight section in the ring available for insertion devices. This paper reviews the DDBA design and layout, the implications for technical subsystems, the associated engineering challenges and the main results of the commissioning completed in April 2017.
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May 2018
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