Knife-edge based measurement of the 4D transverse phase space of electron beams with picometer-scale emittance

Ji, Fuhao; Navarro, J. Giner; Musumeci, P.; Durham, Daniel B.; Minor, Andrew M.; Filippetto, D.

doi:10.1103/physrevaccelbeams.22.082801

Cited by 14 publications

(6 citation statements)

References 33 publications

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“…The normal mode emittances can be calculated if observations are made with different sets of quadrupole strengths between the screens (see, for example, [22,23]): we return to this point in the discussion of the quadrupole scan technique in Section III B. Alternatively, measurements can be made at additional longitudinal positions [24]. Measurements of the 4 × 4 covariance matrix (for picometer-scale emittance beams) using measurements at multiple longitudinal locations were recently reported by Ji et al [10].…”

Section: A Three-screen Methodsmentioning

confidence: 99%

“…There are well-established techniques for emittance and optics measurements, often based on observation of changes in beam size in response to changes in strength of focusing (quadrupole) magnets, or observation of the beam size at different locations along a beam line [1,2]. Beam phase space tomography is also an established method for providing detailed information about the phase space distribution [3][4][5][6][7][8][9][10]. In this paper, we report the results of studies on CLARA FE (Compact Linear Accelerator for Research and Applications, Front End) at Daresbury Laboratory [11,12], aimed at characterising the transverse emittance and optical properties of the electron beam.…”

Section: Introductionmentioning

confidence: 99%

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Transverse phase space characterization in an accelerator test facility

Wolski

Christie

Militsyn

et al. 2020

Phys. Rev. Accel. Beams

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We compare three techniques for characterising the transverse phase space distribution of the beam in CLARA FE (the Compact Linear Accelerator for Research and Applications Front End, at Daresbury Laboratory, UK): emittance and optics measurements using screens at three separate beamline locations; quadrupole scans; and phase space tomography. We find that where the beam distribution has significant structure (as in the case of CLARA FE at the time the measurements presented here were made) tomography analysis is the most reliable way to obtain a meaningful characterisation of the transverse beam properties. We present the first experimental results from four-dimensional phase space tomography: our results show that this technique can provide an insight into beam properties that are of importance for optimising machine performance.

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Section: A Three-screen Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transverse phase space characterization in an accelerator test facility

Wolski

Christie

Militsyn

et al. 2020

Phys. Rev. Accel. Beams

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“…This is strictly true for some beamlines where computing a diagnostic is expensive, e.g. those that involve intensive data processing or a complicated metaroutine like a knife-edge scan [28]. Many beamlines, though, have no latency in the diagnostics and are only expensive to sample because they are expensive to move around.…”

Section: Sampling Expensementioning

confidence: 99%

On-the-fly optimization of synchrotron beamlines using machine learning

Morris

Rakitin

Giles

et al. 2022

Optical System Alignment, Tolerancing, and Verification XIV

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Autonomous methods to align beamlines can decrease the amount of time spent on diagnostics, and also uncover better global optima leading to better beam quality. The alignment of these beamlines is a high-dimensional, expensive-to-sample optimization problem involving the simultaneous treatment of many optical elements with correlated and nonlinear dynamics. Bayesian optimization is a strategy of efficient global optimization that has proved successful in similar regimes in a wide variety of beamline alignment applications, though it has typically been implemented for particular beamlines and optimization tasks. In this paper, we present a basic formulation of Bayesian inference and Gaussian process models as they relate to multiobjective Bayesian optimization, as well as the practical challenges presented by beamline alignment. We show that the same general implementation of Bayesian optimization with special consideration for beamline alignment can quickly learn the dynamics of particular beamlines in an online fashion through hyperparameter fitting with no prior information. We present the implementation of a concise software framework for beamline alignment and test it on four different optimization problems for experiments at x-ray beamlines of the National Synchrotron Light Source II and the Advanced Light Source and an electron beam at the Accelerator Test Facility, along with benchmarking on a simulated digital twin. We discuss new applications of the framework, and the potential for a unified approach to beamline alignment at synchrotron facilities.

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“…At higher beam charges, effects like saturation or space-charge blooming (Murokh et al, 2000) can impede the measurement of smaller spots. Multi-shot techniques, such as moving a knife-edge ( (Ji et al, 2019b) or thin wires in the beam (Borrelli et al, 2018;Orlandi et al, 2020), are better suited for µm scale spot size measurements.…”

Section: Control Of Lateral Coherence and Beam Sizementioning

confidence: 99%

Ultrafast Electron Diffraction: Visualizing Dynamic States of Matter

Filippetto,

Musumeci,

et al. 2022

Preprint

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Since the discovery of electron-wave duality, electron scattering instrumentation has developed into a powerful array of techniques for revealing the atomic structure of matter. Beyond detecting local lattice variations in equilibrium structures with the highest possible spatial resolution, recent research efforts have been directed towards the long sought-after dream of visualizing the dynamic evolution of matter in real-time. The atomic behavior at ultrafast timescales carries critical information on phase transition and chemical reaction dynamics, the coupling of electronic and nuclear degrees of freedom in materials and molecules, the correlation between structure, function and previously hidden metastable or nonequilibrium states of matter. Ultrafast electron pulses play an essential role in this scientific endeavor, and their generation has been facilitated by rapid technical advances in both ultrafast laser and particle accelerator technologies. This review presents a summary of the remarkable developments in this field over the last few decades. The physics and technology of ultrafast electron beams is presented with an emphasis on the figures of merit most relevant for ultrafast electron diffraction (UED) experiments. We discuss recent developments in the generation, manipulation and characterization of ultrashort electron beams aimed at improving the combined spatio-temporal resolution of these measurements. The fundamentals of electron scattering from atomic matter and the theoretical frameworks for retrieving dynamic structural information from solid-state and gas-phase samples is described. Essential experimental techniques and several landmark works that have applied these approaches are also highlighted to demonstrate the widening applicability of these methods. Ultrafast electron probes with ever improving capabilities, combined with other complementary photonbased or spectroscopic approaches, hold tremendous potential for revolutionizing our ability to observe and understand energy and matter at atomic scales.

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Knife-edge based measurement of the 4D transverse phase space of electron beams with picometer-scale emittance

Cited by 14 publications

References 33 publications

Transverse phase space characterization in an accelerator test facility

Transverse phase space characterization in an accelerator test facility

On-the-fly optimization of synchrotron beamlines using machine learning

Ultrafast Electron Diffraction: Visualizing Dynamic States of Matter

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