2011 Particle Accelerator Conference - Table of Session: WEOCN (Instrumentation and Controls III)

Paper

Title

Page

Laser Based Diagnostics for Measuring H^- Beam Parameters

1433

Y. Liu, A.V. Aleksandrov, W. Blokland, C. Deibele, C.D. Long, A.A. Menshov, J. Pogge, A. Webster, A.P. Zhukov
ORNL, Oak Ridge, Tennessee, USA
R.A. Hardin
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: sponsored by the Division of Materials Science, U.S. Department of Energy, under contract number DE-AC05-96OR22464 with UT-Battelle Corporation for Oak Ridge National Laboratory
In recent years, a number of laser based H^- beam diagnostics systems have been developed in the Spallation Neutron Source (SNS). This talk reviews three types of laser based diagnostics at SNS: the laser wire profile monitors at superconducting linac (SCL), the laser transverse emittance scanner at high energy beam transport (HEBT), and the laser bunch shape monitor at medium energy beam transport (MEBT). Measurement performance will be reported and major technical challenges in the design, implementation, and operation of laser based diagnostics at accelerator facilities will be addressed.

Slides WEOCN1 [4.710 MB]

WEOCN2

A Non-Destructive Profile Monitor for High Intensity Beams

1438

W. Blokland, S.M. Cousineau
ORNL, Oak Ridge, Tennessee, USA

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
A non-destructive profile monitor has been installed and commissioned in the accumulator ring of the Spallation Neutron Source (SNS). The SNS Ring accumulates high intensity proton bunches of up to 1.5·10¹⁴ protons with a typical peak current of over 50 A and a bunch length of about 0.7 us during a 1 ms cycle. The profile monitor consists of two systems, one for each plane, with electron guns, correctors, defectors, and quadrupoles to produce pulsed electron beams that scan through the proton bunch. The proton bunch EM fields alter the trajectory of the electrons and their projection on a fluorescent screen. The projection is analyzed to determine the transverse profile of the proton bunch. The speaker will describe the theory, hardware, software, analysis, results, and improvements to these electron scanners. The results include a comparison to wire scanner profiles of extracted ring beam.

Slides WEOCN2 [9.476 MB]

WEOCN3

Operational Results from the LHC Luminosity Monitors

1443

R. Miyamoto
BNL, Upton, Long Island, New York, USA
E. Bravin
CERN, Geneva, Switzerland
H.S. Matis, A. Ratti, W.C. Turner, H. Yaver, T. stezelberger
LBNL, Berkeley, California, USA

Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
The Luminosity Monitors for the high luminosity regions in the LHC have been operating to monitor and optimize the luminosity since the beginning of the 2009 run. The device is a gas ionization chamber, which has the ability to resolve bunch-by-bunch luminosity as well as survive the extreme levels of radiation at nominal high intensity LHC operations. The chambers are installed at the zero degree collision angle inside the neutral absorbers 140 m from the interaction point and monitor showers produced by high energy neutral particles from the collisions. A second device, a photo-multiplier based system (PMT) located directly behind the gas ionization chamber, has been also used at low luminosities. We will present operational results for the ionization chambers for both pp and Pb-Pb collisions. These measurements include signal, noise and background studies, and correlation between the gas ionization detector and the PMT. Also, comparison with ongoing modeling efforts will be included.

Slides WEOCN3 [2.609 MB]

WEOCN4

Electron Beam Diagnostics of the JLab UV FEL

1446

P. Evtushenko, S.V. Benson, G.H. Biallas, J.L. Coleman, C. Dickover, D. Douglas, M. Marchlik, D.W. Sexton, C. Tennant
JLAB, Newport News, Virginia, USA

In this contribution we describe various systems of the electron beam diagnostics of the JLab UV FEL. The FEL is installed on a new bypass beam line of existing 10kW IR Upgrade FEL. Here we describe a set of the following systems. A combination of OTR and phosphor viewers used for measurements of a transverse beam profile, transverse emittance, Twiss parameters. This system is also used for alignment of the optical cavity of the UV oscillator and to ensure the overlap between the electron beam and optical mode in the FEL wiggler. A system of beam position monitors equipped with log-amp based BPM electronics. Bunch length on the order of 120 fs RMS is measured with the help of a modified Martin-Puplett interferometer. The longitudinal transfer function measurements system is used to setup bunch compression in an optimal way such that the LINAC RF curvature is compensated using only higher order magnetic elements of the beam transport. This set of the diagnostics system made its contribution to achieve the first lasing of the FEL after about 60 hours of beam operation.

Slides WEOCN4 [8.864 MB]

WEOCN5

Beam Halo Measurements at UMER and the JLAB FEL Using an Adaptive Masking Method

1449

H.D. Zhang, S. Bernal, R.B. Fiorito, R.A. Kishek, P.G. O'Shea, A.G. Shkvarunets
UMD, College Park, Maryland, USA
S.V. Benson, D. Douglas, F.G. Wilson, S. Zhang
JLAB, Newport News, Virginia, USA

Funding: US Dept. of Energy Offices of High Energy Physics and Fusion Energy Sciences and by the Dept. of Defense Office of Naval Research and Joint Technology Office.
Beam halo is a challenging issue for intense beams since it can cause beam loss, emittance growth, nuclear activation and secondary electron emission. Because of the potentially low number of particles in the halo compared with beam core, traditional imaging methods may not have sufficient contrast to detect faint halos. We have developed a high dynamic range, adaptive masking method to measure halo using a digital micro-mirror array device and demonstrated its effectiveness experimentally on the University of Maryland Electron Ring (UMER). We also report on similar experiments currently in progress at the Jefferson Lab Free Electron Laser (FEL) using this method.

Slides WEOCN5 [1.287 MB]

WEOCN6

Femtosecond Resolved Determination of Electron Beam and XUV Seed Pulse Temporal Overlap in sFLASH

1452

R. Tarkeshian, A. Azima, J. Bödewadt, F. Curbis, M. Drescher, Th. Maltezopoulos, V. Miltchev, M. Mittenzwey, J. Rönsch-Schulenburg, J. Roßbach
Uni HH, Hamburg, Germany
H. Delsim-Hashemi, K. Honkavaara, H. Schlarb, S. Schreiber
DESY, Hamburg, Germany
R. Ischebeck
PSI, Villigen, Switzerland

sFLASH is a seeded experiment at the Free-Electron Laser FLASH in Hamburg. It uses a 38nm High-Harmonic-Generation (HHG) scheme to seed the FEL-process in a 10 m long variable-gap undulator. The temporal overlap between the electron and HHG pulses is critical to the seeding process. The use of a 3rd harmonic accelerating module provides a high current electron beam with ~400 fs bunch duration. The duration of the HHG laser pulse is ∼20 fs. The desired overlap is achieved in two steps. Firstly, the HHG drive laser is synchronized to the incoherent spontaneous radiation from an upstream undulator with picosecond resolution. Next, the coherent radiation from an undulator is used to determine the exact overlap of the electron beam in a modulator-radiator set-up.

Slides WEOCN6 [1.758 MB]

Paper	Title	Page
WEOCN1	Laser Based Diagnostics for Measuring H^- Beam Parameters	1433
	Y. Liu, A.V. Aleksandrov, W. Blokland, C. Deibele, C.D. Long, A.A. Menshov, J. Pogge, A. Webster, A.P. Zhukov ORNL, Oak Ridge, Tennessee, USA R.A. Hardin ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: sponsored by the Division of Materials Science, U.S. Department of Energy, under contract number DE-AC05-96OR22464 with UT-Battelle Corporation for Oak Ridge National Laboratory In recent years, a number of laser based H^- beam diagnostics systems have been developed in the Spallation Neutron Source (SNS). This talk reviews three types of laser based diagnostics at SNS: the laser wire profile monitors at superconducting linac (SCL), the laser transverse emittance scanner at high energy beam transport (HEBT), and the laser bunch shape monitor at medium energy beam transport (MEBT). Measurement performance will be reported and major technical challenges in the design, implementation, and operation of laser based diagnostics at accelerator facilities will be addressed.
	Slides WEOCN1 [4.710 MB]

WEOCN2	A Non-Destructive Profile Monitor for High Intensity Beams	1438
	W. Blokland, S.M. Cousineau ORNL, Oak Ridge, Tennessee, USA
	Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. A non-destructive profile monitor has been installed and commissioned in the accumulator ring of the Spallation Neutron Source (SNS). The SNS Ring accumulates high intensity proton bunches of up to 1.5·10¹⁴ protons with a typical peak current of over 50 A and a bunch length of about 0.7 us during a 1 ms cycle. The profile monitor consists of two systems, one for each plane, with electron guns, correctors, defectors, and quadrupoles to produce pulsed electron beams that scan through the proton bunch. The proton bunch EM fields alter the trajectory of the electrons and their projection on a fluorescent screen. The projection is analyzed to determine the transverse profile of the proton bunch. The speaker will describe the theory, hardware, software, analysis, results, and improvements to these electron scanners. The results include a comparison to wire scanner profiles of extracted ring beam.
	Slides WEOCN2 [9.476 MB]

WEOCN3	Operational Results from the LHC Luminosity Monitors	1443
	R. Miyamoto BNL, Upton, Long Island, New York, USA E. Bravin CERN, Geneva, Switzerland H.S. Matis, A. Ratti, W.C. Turner, H. Yaver, T. stezelberger LBNL, Berkeley, California, USA
	Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP). The Luminosity Monitors for the high luminosity regions in the LHC have been operating to monitor and optimize the luminosity since the beginning of the 2009 run. The device is a gas ionization chamber, which has the ability to resolve bunch-by-bunch luminosity as well as survive the extreme levels of radiation at nominal high intensity LHC operations. The chambers are installed at the zero degree collision angle inside the neutral absorbers 140 m from the interaction point and monitor showers produced by high energy neutral particles from the collisions. A second device, a photo-multiplier based system (PMT) located directly behind the gas ionization chamber, has been also used at low luminosities. We will present operational results for the ionization chambers for both pp and Pb-Pb collisions. These measurements include signal, noise and background studies, and correlation between the gas ionization detector and the PMT. Also, comparison with ongoing modeling efforts will be included.
	Slides WEOCN3 [2.609 MB]

WEOCN4	Electron Beam Diagnostics of the JLab UV FEL	1446
	P. Evtushenko, S.V. Benson, G.H. Biallas, J.L. Coleman, C. Dickover, D. Douglas, M. Marchlik, D.W. Sexton, C. Tennant JLAB, Newport News, Virginia, USA
	In this contribution we describe various systems of the electron beam diagnostics of the JLab UV FEL. The FEL is installed on a new bypass beam line of existing 10kW IR Upgrade FEL. Here we describe a set of the following systems. A combination of OTR and phosphor viewers used for measurements of a transverse beam profile, transverse emittance, Twiss parameters. This system is also used for alignment of the optical cavity of the UV oscillator and to ensure the overlap between the electron beam and optical mode in the FEL wiggler. A system of beam position monitors equipped with log-amp based BPM electronics. Bunch length on the order of 120 fs RMS is measured with the help of a modified Martin-Puplett interferometer. The longitudinal transfer function measurements system is used to setup bunch compression in an optimal way such that the LINAC RF curvature is compensated using only higher order magnetic elements of the beam transport. This set of the diagnostics system made its contribution to achieve the first lasing of the FEL after about 60 hours of beam operation.
	Slides WEOCN4 [8.864 MB]

WEOCN5	Beam Halo Measurements at UMER and the JLAB FEL Using an Adaptive Masking Method	1449
	H.D. Zhang, S. Bernal, R.B. Fiorito, R.A. Kishek, P.G. O'Shea, A.G. Shkvarunets UMD, College Park, Maryland, USA S.V. Benson, D. Douglas, F.G. Wilson, S. Zhang JLAB, Newport News, Virginia, USA
	Funding: US Dept. of Energy Offices of High Energy Physics and Fusion Energy Sciences and by the Dept. of Defense Office of Naval Research and Joint Technology Office. Beam halo is a challenging issue for intense beams since it can cause beam loss, emittance growth, nuclear activation and secondary electron emission. Because of the potentially low number of particles in the halo compared with beam core, traditional imaging methods may not have sufficient contrast to detect faint halos. We have developed a high dynamic range, adaptive masking method to measure halo using a digital micro-mirror array device and demonstrated its effectiveness experimentally on the University of Maryland Electron Ring (UMER). We also report on similar experiments currently in progress at the Jefferson Lab Free Electron Laser (FEL) using this method.
	Slides WEOCN5 [1.287 MB]

WEOCN6	Femtosecond Resolved Determination of Electron Beam and XUV Seed Pulse Temporal Overlap in sFLASH	1452
	R. Tarkeshian, A. Azima, J. Bödewadt, F. Curbis, M. Drescher, Th. Maltezopoulos, V. Miltchev, M. Mittenzwey, J. Rönsch-Schulenburg, J. Roßbach Uni HH, Hamburg, Germany H. Delsim-Hashemi, K. Honkavaara, H. Schlarb, S. Schreiber DESY, Hamburg, Germany R. Ischebeck PSI, Villigen, Switzerland
	sFLASH is a seeded experiment at the Free-Electron Laser FLASH in Hamburg. It uses a 38nm High-Harmonic-Generation (HHG) scheme to seed the FEL-process in a 10 m long variable-gap undulator. The temporal overlap between the electron and HHG pulses is critical to the seeding process. The use of a 3rd harmonic accelerating module provides a high current electron beam with ~400 fs bunch duration. The duration of the HHG laser pulse is ∼20 fs. The desired overlap is achieved in two steps. Firstly, the HHG drive laser is synchronized to the incoherent spontaneous radiation from an upstream undulator with picosecond resolution. Next, the coherent radiation from an undulator is used to determine the exact overlap of the electron beam in a modulator-radiator set-up.
	Slides WEOCN6 [1.758 MB]