LINAC2016 - Classification: 3 Technology / 3G Beam Diagnostics

Paper	Title	Page
TUOP11	Methods for Bunch Shape Monitor Phase Resolution Improvement	408
TUPRC027	use link to see paper's listing under its alternate paper code
	A. Feschenko, S.A. Gavrilov RAS/INR, Moscow, Russia
	Bunch shape monitors, based on secondary electrons emission, are widely used for measurements of longitudinal bunch profiles during a linac commissioning and initial optimization of beam dynamics. A typical phase resolution of these devices is about 1°. However it becomes insufficient for new modern linacs, which require a better resolution. Some developed methods for a phase resolution improvement are discussed.
	Slides TUOP11 [21.248 MB]
	Poster TUOP11 [1.888 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP11
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TH2A02	Results From the Laserwire Emittance Scanner and Profile Monitor at CERN's Linac4	715
	T. Hofmann, U. Raich, F. Roncarolo CERN, Geneva, Switzerland G.E. Boorman, A. Bosco, S.M. Gibson Royal Holloway, University of London, Surrey, United Kingdom G.E. Boorman, A. Bosco, S.M. Gibson JAI, Egham, Surrey, United Kingdom
	A novel, non-invasive, H⁻ laser-wire scanner has been tested during the beam commissioning of CERN's new Linac4. Emittance measurements were performed at beam energies of 3 and 12 MeV with this new device and were found to closely match the results of conventional slit-grid methods. In 2015, the configuration of this laser-wire scanner was substantially modified. In the new setup the electrons liberated by the photo-detachment process are deflected away from the main beam and focused onto a single crystal diamond detector that can be moved in order to follow the laser beam scan. The beam profiles measured with the new laser-wire setup at 50 MeV, 80 MeV and 10⁷ MeV are in good agreement with the measurements of nearby SEM grids and wire-scanners. The design of the final laser-wire scanner for the full 160 MeV beam energy will also be presented. In Linac4 two independent laser-wire devices will be installed in the transfer line to the BOOSTER ring. Each device will be composed of two parts: one hosting the laser-wire and the electron detector and the second hosting the segmented diamond detector used to acquire the transverse profiles of the H⁰ beamlets.
	Slides TH2A02 [3.164 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH2A02
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THPRC026	Optical Design of the PI-Test MEBT Beam Scraping System	827
	A. Saini, A.V. Shemyakin Fermilab, Batavia, Illinois, USA
	PI-Test [1] is an accelerator facility under construction at Fermilab that will provide a platform to demonstrate critical technologies and concept of front-end of the PIP-II superconducting radio frequency (SRF) linac. It will be capable to accelerate an H⁻ ion beam with average current of 2 mA up to 25 MeV in continuous wave (CW) regime. To protect the SRF components from beam irradiation, the Medium Energy Beam Transport (MEBT) section of PI-Test includes an elaborated beam scraping system. It consists of four assemblies spread along the MEBT, with each assembly composed of four radiation-cooled, electrically isolated plates that can be moved into the beam in horizontal and vertical direction. The primary objectives of scraping system are to intercept particles with large transverse action and to protect the beamline elements and SRF linac in case of errors with beam focusing or steering. In this paper we formulate requirements for the scraping system and discuss factors affecting its efficiency. An optical design compatible with PI-Test MEBT is also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC026
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPLR015	Fifth-Order Moment Correction for Beam Position and Second-Order Moment Measurement	876
	K. Yanagida, H. Hanaki, S. Suzuki JASRI/SPring-8, Hyogo-ken, Japan
	For precise beam position measurement using a beam position monitor (BPM), a recursive correction which is expressed by the higher-order polynomials of beam positions are usually adopted. We recognized that the higher-order polynomials came from the higher-order moments and that beam position measurement is consequently influenced by a transverse beam shape. To investigate what order was required for adequate correction, we performed a successive iteration for the six-electrode BPM holding an inner radius of 16mm (circular cross-section). The successive iteration is a method to obtain a self-consistent solution for the higher-order correction. An amplitude of static electric field due to a beam charge was calculated by two-dimensional mirror charge method. As a result of the successive iteration, the convergence region was large enough for ordinary measurements (from lower than -5mm to higher than 5mm horizontally and vertically). In the convergence region the root mean square of the differences between the set and calculated vertical position were obtained as 0.487mm (without correction), 0.030mm (with third-order correction) and 0.003mm (with fifth-order correction).
	Poster THPLR015 [6.049 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR015
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

TUOP11

Methods for Bunch Shape Monitor Phase Resolution Improvement

408

TUPRC027

use link to see paper's listing under its alternate paper code

A. Feschenko, S.A. Gavrilov
RAS/INR, Moscow, Russia

Bunch shape monitors, based on secondary electrons emission, are widely used for measurements of longitudinal bunch profiles during a linac commissioning and initial optimization of beam dynamics. A typical phase resolution of these devices is about 1°. However it becomes insufficient for new modern linacs, which require a better resolution. Some developed methods for a phase resolution improvement are discussed.

Slides TUOP11 [21.248 MB]

Poster TUOP11 [1.888 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP11

Export •

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

TH2A02

Results From the Laserwire Emittance Scanner and Profile Monitor at CERN's Linac4

715

T. Hofmann, U. Raich, F. Roncarolo
CERN, Geneva, Switzerland
G.E. Boorman, A. Bosco, S.M. Gibson
Royal Holloway, University of London, Surrey, United Kingdom
G.E. Boorman, A. Bosco, S.M. Gibson
JAI, Egham, Surrey, United Kingdom

A novel, non-invasive, H⁻ laser-wire scanner has been tested during the beam commissioning of CERN's new Linac4. Emittance measurements were performed at beam energies of 3 and 12 MeV with this new device and were found to closely match the results of conventional slit-grid methods. In 2015, the configuration of this laser-wire scanner was substantially modified. In the new setup the electrons liberated by the photo-detachment process are deflected away from the main beam and focused onto a single crystal diamond detector that can be moved in order to follow the laser beam scan. The beam profiles measured with the new laser-wire setup at 50 MeV, 80 MeV and 10⁷ MeV are in good agreement with the measurements of nearby SEM grids and wire-scanners. The design of the final laser-wire scanner for the full 160 MeV beam energy will also be presented. In Linac4 two independent laser-wire devices will be installed in the transfer line to the BOOSTER ring. Each device will be composed of two parts: one hosting the laser-wire and the electron detector and the second hosting the segmented diamond detector used to acquire the transverse profiles of the H⁰ beamlets.

Slides TH2A02 [3.164 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH2A02

Export •

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

THPRC026

Optical Design of the PI-Test MEBT Beam Scraping System

827

A. Saini, A.V. Shemyakin
Fermilab, Batavia, Illinois, USA

PI-Test [1] is an accelerator facility under construction at Fermilab that will provide a platform to demonstrate critical technologies and concept of front-end of the PIP-II superconducting radio frequency (SRF) linac. It will be capable to accelerate an H⁻ ion beam with average current of 2 mA up to 25 MeV in continuous wave (CW) regime. To protect the SRF components from beam irradiation, the Medium Energy Beam Transport (MEBT) section of PI-Test includes an elaborated beam scraping system. It consists of four assemblies spread along the MEBT, with each assembly composed of four radiation-cooled, electrically isolated plates that can be moved into the beam in horizontal and vertical direction. The primary objectives of scraping system are to intercept particles with large transverse action and to protect the beamline elements and SRF linac in case of errors with beam focusing or steering. In this paper we formulate requirements for the scraping system and discuss factors affecting its efficiency. An optical design compatible with PI-Test MEBT is also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC026

Export •

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

THPLR015

Fifth-Order Moment Correction for Beam Position and Second-Order Moment Measurement

876

K. Yanagida, H. Hanaki, S. Suzuki
JASRI/SPring-8, Hyogo-ken, Japan

For precise beam position measurement using a beam position monitor (BPM), a recursive correction which is expressed by the higher-order polynomials of beam positions are usually adopted. We recognized that the higher-order polynomials came from the higher-order moments and that beam position measurement is consequently influenced by a transverse beam shape. To investigate what order was required for adequate correction, we performed a successive iteration for the six-electrode BPM holding an inner radius of 16mm (circular cross-section). The successive iteration is a method to obtain a self-consistent solution for the higher-order correction. An amplitude of static electric field due to a beam charge was calculated by two-dimensional mirror charge method. As a result of the successive iteration, the convergence region was large enough for ordinary measurements (from lower than -5mm to higher than 5mm horizontally and vertically). In the convergence region the root mean square of the differences between the set and calculated vertical position were obtained as 0.487mm (without correction), 0.030mm (with third-order correction) and 0.003mm (with fifth-order correction).

Poster THPLR015 [6.049 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR015

Export •

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