FEL2019 - List of Keywords (diagnostics)

Paper	Title	Other Keywords	Page
WEA04	Growing and Characterization of Cs2Te Photocatodes with Different Thicknesses at INFN LASA	cathode, electron, gun, FEL	297
	L. Monaco, P. Michelato, D. Sertore INFN/LASA, Segrate (MI), Italy G. Guerini Rocco, C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy
	The INFN LASA group has a long standing experience in the production of cesium telluride photocathodes for high brightness photoinjectors. The well-established recipe relies on the deposition of a typical amount of 10 nm of Te, followed by the Cs deposition until reaching the maximum QE. Nevertheless, for improving the understanding of photocathode properties, we are investigating the effect of Te thickness on the growing process, evaluating photocathode optical properties and quantum efficiency during the growing process and on the final film. These photocathodes will be then operated and analyzed in the real environment of the RF Gun at the PITZ facility in DESY Zeuthen, to estimate their impact on the electron beam properties.
	Slides WEA04 [15.703 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEA04
About •	paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEB01	Identification and Mitigation of Smoke-Ring Effects in Scintillator-Based Electron Beam Images at the European XFEL	FEL, electron, experiment, ECR	301
	G. Kube, S. Liu, A.I. Novokshonov, M. Scholz DESY, Hamburg, Germany
	Standard transverse beam profile measurements at the European XFEL are based on scintillating screen monitors using LYSO:Ce. While it is possible to resolve beam sizes down to a few micrometers with this scintillator, the experience during the XFEL commissioning showed that the measured emittance values were significantly larger than the expected ones. In addition, beam profiles measured at bunch charges of a few hundred pC showed a ’smoke ring’ structure. While coherent OTR emission and beam dynamical influence can be excluded, it is assumed that the profile distortions are caused by effects from the scintillator material. Following the experience in high energy physics, a simple model was developed which takes into account quenching effects of excitonic carriers inside a scintillator in a heuristic way. Based on this model, the observed beam profiles can be understood qualitatively. Together with the model description, first comparisons with experimental results will be shown. Possible new scintillator materials suitable for beam profile diagnostics and first test results from beam measurements will be presented.
	Slides WEB01 [5.057 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEB01
About •	paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEB03	Application of Machine Learning to Beam Diagnostics	optics, network, controls, target	311
	E. Fol, R. Tomás CERN, Meyrin, Switzerland J.M. Coello de Portugal PSI, Villigen PSI, Switzerland G. Franchetti GSI, Darmstadt, Germany
	Machine Learning (ML) techniques are widely used in science and industry to discover relevant information and make predictions from data. The application ranges from face recognition to High Energy Physics experiments. Recently, the application of ML has grown also in accelerator physics and in particular in the domain of diagnostics and control. The target is to provide an overview of ML techniques and to indicate beam diagnostics tasks where ML based solutions can be efficiently applied to complement or potentially surpass existing methods. Besides, a short summary of recent works will be given demonstrating the great interest for use of ML concepts in beam diagnostics and latest results of incorporating these concepts into accelerator problems, with the focus on beam optics related application.
	Slides WEB03 [5.721 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEB03
About •	paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP041	Feasibility of Single-Shot Microbunching Diagnostics for a Pre-Bunched Beam at 266 nm	electron, laser, bunching, radiation	408
	A.H. Lumpkin AAI/ANL, Lemont, Illinois, USA D.W. Rule Private Address, Silver Spring, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. Co-propagating a relativistic electron beam and a high-power laser pulse through a short undulator (modulator) provides an energy modulation which can be converted to a periodic longitudinal density modulation (or microbunching) via the R56 term of a chicane. Such pre-bunching of a beam at the resonant wavelength and the harmonics of a subsequent free-electron laser (FEL) amplifier seeds the process and results in improved gain. We describe potential characterizations of the resulting microbunched electron beams using coherent optical transition radiation (COTR) imaging techniques for transverse size (50 micron), divergence (sub-mrad), trajectory angle (0.1 mrad), spectrum (few nm), and pulse length (sub-ps). The transverse spatial alignment is provided with near-field imaging and the angular alignment is done with far-field imaging and two-foil COTR interferometry (COTRI). Analytical model results for a 266-nm wavelength COTRI case with a 10% microbunching fraction will be presented. COTR gains of 7 million were calculated for an initial charge of 300 pC which enables splitting the optical signal for single-shot measurements of all the cited parameters.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP041
About •	paper received ※ 20 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

WEA04

Growing and Characterization of Cs2Te Photocatodes with Different Thicknesses at INFN LASA

cathode, electron, gun, FEL

297

L. Monaco, P. Michelato, D. Sertore
INFN/LASA, Segrate (MI), Italy
G. Guerini Rocco, C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy

The INFN LASA group has a long standing experience in the production of cesium telluride photocathodes for high brightness photoinjectors. The well-established recipe relies on the deposition of a typical amount of 10 nm of Te, followed by the Cs deposition until reaching the maximum QE. Nevertheless, for improving the understanding of photocathode properties, we are investigating the effect of Te thickness on the growing process, evaluating photocathode optical properties and quantum efficiency during the growing process and on the final film. These photocathodes will be then operated and analyzed in the real environment of the RF Gun at the PITZ facility in DESY Zeuthen, to estimate their impact on the electron beam properties.

Slides WEA04 [15.703 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEA04

About •

paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEB01

Identification and Mitigation of Smoke-Ring Effects in Scintillator-Based Electron Beam Images at the European XFEL

FEL, electron, experiment, ECR

301

G. Kube, S. Liu, A.I. Novokshonov, M. Scholz
DESY, Hamburg, Germany

Standard transverse beam profile measurements at the European XFEL are based on scintillating screen monitors using LYSO:Ce. While it is possible to resolve beam sizes down to a few micrometers with this scintillator, the experience during the XFEL commissioning showed that the measured emittance values were significantly larger than the expected ones. In addition, beam profiles measured at bunch charges of a few hundred pC showed a ’smoke ring’ structure. While coherent OTR emission and beam dynamical influence can be excluded, it is assumed that the profile distortions are caused by effects from the scintillator material. Following the experience in high energy physics, a simple model was developed which takes into account quenching effects of excitonic carriers inside a scintillator in a heuristic way. Based on this model, the observed beam profiles can be understood qualitatively. Together with the model description, first comparisons with experimental results will be shown. Possible new scintillator materials suitable for beam profile diagnostics and first test results from beam measurements will be presented.

Slides WEB01 [5.057 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEB01

About •

paper received ※ 20 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEB03

Application of Machine Learning to Beam Diagnostics

optics, network, controls, target

311

E. Fol, R. Tomás
CERN, Meyrin, Switzerland
J.M. Coello de Portugal
PSI, Villigen PSI, Switzerland
G. Franchetti
GSI, Darmstadt, Germany

Machine Learning (ML) techniques are widely used in science and industry to discover relevant information and make predictions from data. The application ranges from face recognition to High Energy Physics experiments. Recently, the application of ML has grown also in accelerator physics and in particular in the domain of diagnostics and control. The target is to provide an overview of ML techniques and to indicate beam diagnostics tasks where ML based solutions can be efficiently applied to complement or potentially surpass existing methods. Besides, a short summary of recent works will be given demonstrating the great interest for use of ML concepts in beam diagnostics and latest results of incorporating these concepts into accelerator problems, with the focus on beam optics related application.

Slides WEB03 [5.721 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEB03

About •

paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP041

Feasibility of Single-Shot Microbunching Diagnostics for a Pre-Bunched Beam at 266 nm

electron, laser, bunching, radiation

408

A.H. Lumpkin
AAI/ANL, Lemont, Illinois, USA
D.W. Rule
Private Address, Silver Spring, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Co-propagating a relativistic electron beam and a high-power laser pulse through a short undulator (modulator) provides an energy modulation which can be converted to a periodic longitudinal density modulation (or microbunching) via the R56 term of a chicane. Such pre-bunching of a beam at the resonant wavelength and the harmonics of a subsequent free-electron laser (FEL) amplifier seeds the process and results in improved gain. We describe potential characterizations of the resulting microbunched electron beams using coherent optical transition radiation (COTR) imaging techniques for transverse size (50 micron), divergence (sub-mrad), trajectory angle (0.1 mrad), spectrum (few nm), and pulse length (sub-ps). The transverse spatial alignment is provided with near-field imaging and the angular alignment is done with far-field imaging and two-foil COTR interferometry (COTRI). Analytical model results for a 266-nm wavelength COTRI case with a 10% microbunching fraction will be presented. COTR gains of 7 million were calculated for an initial charge of 300 pC which enables splitting the optical signal for single-shot measurements of all the cited parameters.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP041

About •

paper received ※ 20 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)