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| 2. |
- Eriksson, Mikael, et al.
(author)
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Using Multi-Bend Achromats in Synchrotron Radiation Sources
- 2008
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In: Proceedings of EPAC08. ; , s. 2007-2009
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Conference paper (peer-reviewed)abstract
- Multi-bend achromats offer small electron beam emittance, large energy acceptance and a good dynamic aperture. Two examples are discussed below, each using 7-bend achromats; a 12 achromat lattice and a 20 achromat one. Some possible technical solutions associated with the dense lattices are discussed: magnet technology, vacuum system and RF system. Some characteristics of the two rings are also presented; effects of Intra Beam Scattering, Touschek life-time and the electron beam parameter values.
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| 3. |
- Fernandes Tavares, Pedro, et al.
(author)
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Equilibrium bunch density distribution with passive harmonic cavities in a storage ring
- 2014
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In: Physical Review Special Topics. Accelerators and Beams. - 1098-4402. ; 17:6
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Journal article (peer-reviewed)abstract
- The MAX IV storage rings, currently under construction in Lund, Sweden, will use third harmonic cavities operated passively to lengthen the bunches and alleviate collective instabilities. These cavities are an essential ingredient in the MAX IV design concept and are required for achieving the final design goals in terms of stored current, beam emittance, and beam lifetime-such performance challenges are in fact common to all recent ultralow emittance storage ring designs and harmonic cavities are currently under consideration in several laboratories. In this paper, we report on parametric studies comparing different harmonic cavity settings in terms of the resulting bunch length, peak bunch density, and incoherent synchrotron frequency spread for the MAX IV 3 GeV ring. The equilibrium longitudinal bunch density distribution was calculated by establishing a self-consistent equation for the bunch form factor, describing the bunch shape. The calculations are fully self-consistent in the sense that not only the amplitude but also the phase of the waves excited by the beam in the harmonic cavity were assumed to be a function of the bunch shape, which allowed us to explore a wide parameter range not restricted to the region close to the conditions for which the first and second derivatives of the total rf voltage are zero at the synchronous phase. Our results indicate that up to a factor 5 increase in rms bunch length is achievable with a purely passive system for the MAX IV 3 GeV ring while keeping a relatively large harmonic cavity detuning, thus limiting the unavoidable Robinson antidamping rate from the fundamental mode of a passively operated harmonic cavity to values below the synchrotron radiation damping rate. The paper is complemented by results of measurements performed in the MAX III storage ring, which showed good agreement with calculations following the fully self-consistent approach.
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| 4. |
- Jebali, R., et al.
(author)
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A first comparison of the responses of a He-4-based fast-neutron detector and a NE-213 liquid-scintillator reference detector
- 2015
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In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576 .- 0167-5087. ; 794, s. 102-108
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Journal article (peer-reviewed)abstract
- A first comparison has been made between the pulse-shape discrimination characteristics of a novel He-4-based pressurized scintillation detector and a NE-213 liquicl-scintillator reference detector using an Am/Be mixed-field neutron and gamma-ray source and a high-resolution scintillation-pulse digitizer. In particular, the capabilities of the two fast neutron detectors to discriminate between neutrons and gamma-rays were investigated. The NE-213 liquicl-scintillator reference cell produced a wide range of scintillation-light yields in response to he gamma-ray field of the source. In stark contrast, clue to the size and pressure of the He-4 gas volume, the He-4-based detector registered a maximum scintillation-light yield of 750 keV(ee) to the same gamma-ray field. Pulse-shape discrimination for particles with scintillation-light yields of more than 750 keV(ee) was excellent in the case of the He-4-based detector. Above 750 keV(ee) its signal was unambiguously neutron, enabling particle identification based entirely upon the amount of scintillation light produced. (C) 2015 The Authors. Published by Elsevier B.V.
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| 5. |
- Rosborg, Anders
(author)
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Electron beam sizes and lifetimes at MAX II and MAX III
- 2012
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Doctoral thesis (other academic/artistic)abstract
- The MAX II and MAX III synchrotron light sources at MAX-lab provide synchrotron radiation for experiments in a wide variety of research fields. The synchrotron radiation is emitted by ultra-relativistic electrons circulating in electron storage rings. In this thesis the transverse and longitudinal electron beam sizes and the electron beam lifetime limitations in electron storage rings are discussed and the methods used at MAX-lab to measure them are described. The thesis describes how measurements of the electron beam sizes and lifetimes were used to investigate and improve the performance of MAX III and to evaluate a change in the MAX II vacuum system. MAX II was the first synchrotron light source to install nonevaporable getter (NEG)-coated dipole vacuum chambers. They were installed in order to test the feasibility of the MAX IV 3 GeV storage ring vacuum design, where NEG-coated dipole chambers are an integral part of the design. From measurements of the lifetime limitations in MAX II it was concluded that NEG-coated dipole vacuum chambers do not appear to have any negative impact on the performance and operation of a synchrotron light source. A diagnostic beam line was designed and installed in MAX III in order to determine the transverse electron beam profile. The performance of the beam line was investigated by conducting a series of measurements at different beam line settings. There was good agreement between the determined beam sizes for the different settings. The diagnostic beam line was used to determine the horizontal and vertical dispersion and emittance in MAX III at low currents, and an increase in the momentum spread from longitudinal instabilities at higher currents. By adding a second passive Landau cavity to the MAX III radio frequency (RF) system the instabilities were damped in the main window of operation. Measurements of the longitudinal beam size and the induced voltages in the passive cavities agreed well with computer simulations of the triple RF system of MAX III. At high Landau cavity voltages a stable overstretched bunch shape with two regions of phase stability was observed. The lifetime limitations and acceptances in MAX III were determined and the location of a horizontal aperture restriction was identified. Removing the aperture restriction increased the lifetime in MAX III by a factor of two.
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| 6. |
- Rosborg, Anders, et al.
(author)
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Experiences from nonevaporable getter-coated vacuum chambers at the MAX II synchrotron light source
- 2010
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In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 1520-8559 .- 0734-2101. ; 28:2, s. 220-225
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Journal article (peer-reviewed)abstract
- Vacuum chambers coated with nonevaporable getter (NEG) materials have been used in straight sections of synchrotron light sources for the past 10 years. The MAX II storage ring, where four NEG-coated insertion device vacuum chambers and three NEG-coated dipole vacuum chambers have been installed, is the first synchrotron light source to also use NEG-coated dipole vacuum chambers. In connection with the installation of the latest two NEG-coated dipole chambers in April 2009, the evolution of the pressure and lifetime-limiting effects in MAX II has been determined from measurements with movable scrapers. The results have been compared with results from scraper measurements done in 2003, before any NEG-coated vacuum chambers were installed in the storage ring. Less than three months after the installation of the latest dipole chambers the vacuum system in MAX II was performing well with a pressure already lower than the pressure measured in 2003. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3281432]
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| 7. |
- Rosborg, Anders, et al.
(author)
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Transverse electron beam imaging system using visible synchrotron radiation at MAX III
- 2012
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In: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 671, s. 94-102
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Journal article (peer-reviewed)abstract
- The diagnostic beam line at the MAX III synchrotron light source utilizes the synchrotron radiation (SR) in the visible to ultraviolet range to form images of the transverse electron beam profile. The emission and subsequent propagation and focusing of the SR is modeled, taking into account effects such as diffraction and the longitudinally distributed SR generation. A detailed description of the setup of the beam line and method used to determine the transverse beam profile is given in the paper. In order to investigate the imaging method, a series of measurements were performed where the beam line configuration was varied to utilize different wavelengths and polarizations of the SR and different horizontal opening angles of the measurement system. A suggestion is made how to measure future small horizontal beam sizes. (C) 2011 Elsevier B.V. All rights reserved.
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| 8. |
- Ursby, Thomas, et al.
(author)
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BioMAX the first macromolecular crystallography beamline at MAX IV Laboratory
- 2020
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In: Journal of Synchrotron Radiation. - Chichester : Wiley-Blackwell. - 0909-0495 .- 1600-5775. ; 27, s. 1415-1429
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Journal article (peer-reviewed)abstract
- BioMAX is the first macromolecular crystallography beamline at the MAX IV Laboratory 3 GeV storage ring, which is the first operational multi-bend achromat storage ring. Due to the low-emittance storage ring, BioMAX has a parallel, high-intensity X-ray beam, even when focused down to 20 μm × 5 μm using the bendable focusing mirrors. The beam is tunable in the energy range 5-25 keV using the in-vacuum undulator and the horizontally deflecting double-crystal monochromator. BioMAX is equipped with an MD3 diffractometer, an ISARA high-capacity sample changer and an EIGER 16M hybrid pixel detector. Data collection at BioMAX is controlled using the newly developed MXCuBE3 graphical user interface, and sample tracking is handled by ISPyB. The computing infrastructure includes data storage and processing both at MAX IV and the Lund University supercomputing center LUNARC. With state-of-the-art instrumentation, a high degree of automation, a user-friendly control system interface and remote operation, BioMAX provides an excellent facility for most macromolecular crystallography experiments. Serial crystallography using either a high-viscosity extruder injector or the MD3 as a fixed-target scanner is already implemented. The serial crystallography activities at MAX IV Laboratory will be further developed at the microfocus beamline MicroMAX, when it comes into operation in 2022. MicroMAX will have a 1 μm × 1 μm beam focus and a flux up to 1015 photons s with main applications in serial crystallography, room-temperature structure determinations and time-resolved experiments.
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