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Siano M, Geloni G, Paroli B, Butti D, Lefèvre T, Mazzoni S, Trad G, Iriso U, Nosych AA, Torino L, Potenza MAC. FOCUS: fast Monte Carlo approach to coherence of undulator sources. J Synchrotron Radiat 2023; 30:217-226. [PMID: 36601940 PMCID: PMC9814064 DOI: 10.1107/s1600577522010748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 11/10/2022] [Indexed: 06/17/2023]
Abstract
FOCUS (Fast Monte CarlO approach to Coherence of Undulator Sources) is a new GPU-based simulation code to compute the transverse coherence of undulator radiation from ultra-relativistic electrons. The core structure of the code, which is written in the language C++ accelerated with CUDA, combines an analytical description of the emitted electric fields and massively parallel computations on GPUs. The combination is rigorously justified by a statistical description of synchrotron radiation based on a Fourier optics approach. FOCUS is validated by direct comparison with multi-electron Synchrotron Radiation Workshop (SRW) simulations, evidencing a reduction in computation times by up to five orders of magnitude on a consumer laptop. FOCUS is then applied to systematically study the transverse coherence in typical third- and fourth-generation facilities, highlighting peculiar features of undulator sources close to the diffraction limit. FOCUS is aimed at fast evaluation of the transverse coherence of undulator radiation as a function of the electron beam parameters, to support and help prepare more advanced and detailed numerical simulations with traditional codes like SRW.
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Affiliation(s)
- M. Siano
- Dipartimento di Fisica, Università degli Studi di Milano, INFN Sezione di Milano, and CIMAINA, via G. Celoria 16, 20133 Milan, Italy
| | - G. Geloni
- European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - B. Paroli
- Dipartimento di Fisica, Università degli Studi di Milano, INFN Sezione di Milano, and CIMAINA, via G. Celoria 16, 20133 Milan, Italy
| | - D. Butti
- CERN, CH-1211 Geneva, Switzerland
| | | | | | - G. Trad
- CERN, CH-1211 Geneva, Switzerland
| | - U. Iriso
- ALBA-CELLS Synchrotron Radiation Facility, Carrer de la Llum 2-26, 08290 Cerdanyola del Valles, Barcelona, Spain
| | - A. A. Nosych
- ALBA-CELLS Synchrotron Radiation Facility, Carrer de la Llum 2-26, 08290 Cerdanyola del Valles, Barcelona, Spain
| | - L. Torino
- ALBA-CELLS Synchrotron Radiation Facility, Carrer de la Llum 2-26, 08290 Cerdanyola del Valles, Barcelona, Spain
| | - M. A. C. Potenza
- Dipartimento di Fisica, Università degli Studi di Milano, INFN Sezione di Milano, and CIMAINA, via G. Celoria 16, 20133 Milan, Italy
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Khubbutdinov R, Menushenkov AP, Vartanyants IA. Coherence properties of the high-energy fourth-generation X-ray synchrotron sources. J Synchrotron Radiat 2019; 26:1851-1862. [PMID: 31721727 PMCID: PMC6853378 DOI: 10.1107/s1600577519013079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 09/23/2019] [Indexed: 05/22/2023]
Abstract
An analysis of the coherence properties of the fourth-generation high-energy storage rings with emittance values of 10 pm rad is performed. It is presently expected that a storage ring with these low emittance values will reach diffraction limit at hard X-rays. Simulations of coherence properties were performed with the XRT software and an analytical approach for different photon energies from 500 eV to 50 keV. It was demonstrated that a minimum photon emittance (diffraction limit) reached at such storage rings is λ/2π. Using mode decomposition it is shown that, for the parameters of the storage ring considered in this work, the diffraction limit will be reached for soft X-ray energies of 500 eV. About ten modes will contribute to the radiation field at 12 keV photon energy and even more modes give a contribution at higher photon energies. Energy spread effects of the electron beam in a low-emittance storage ring were analysed in detail. Simulations were performed at different relative energy spread values from zero to 2 × 10-3. A decrease of the degree of coherence with an increase of the relative energy spread value was observed. This analysis shows that, to reach the diffraction limit for high photon energies, electron beam emittance should go down to 1 pm rad and below.
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Affiliation(s)
- R. Khubbutdinov
- Deutsches Electronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe shosse 31, Moscow 115409, Russian Federation
| | - A. P. Menushenkov
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe shosse 31, Moscow 115409, Russian Federation
| | - I. A. Vartanyants
- Deutsches Electronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe shosse 31, Moscow 115409, Russian Federation
- Correspondence e-mail:
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Salari V, Sajadi M, Bassereh H, Rezania V, Alaei M, Tuszynski JA. On the classical vibrational coherence of carbonyl groups in the selectivity filter backbone of the KcsA ion channel. J Integr Neurosci 2015; 14:195-206. [PMID: 25990939 DOI: 10.1142/s0219635215500132] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It has been suggested that quantum coherence in the selectivity filter of ion channel may play a key role in fast conduction and selectivity of ions. However, it has not been clearly elucidated yet why classical coherence is not sufficient for this purpose. In this paper, we investigate the classical vibrational coherence between carbonyl groups oscillations in the selectivity filter of KcsA ion channels based on the data obtained from molecular dynamics simulations. Our results show that classical coherence plays no effective role in fast ionic conduction.
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Affiliation(s)
- V Salari
- Department of Physics, Isfahan University of Technology, Isfahan 84156-83111, Iran.,Foundations of Physics Group, School of Physics, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran
| | - M Sajadi
- Department of Physics, University of Shahrekord, Shahrekord, 88186/3414, Iran
| | - H Bassereh
- Department of Physics, Isfahan University of Technology, Isfahan 84156-83111, Iran
| | - V Rezania
- Department of Physical Sciences, Grant MacEwan University, Edmonton T5J 4S2, Canada
| | - M Alaei
- Department of Physics, Isfahan University of Technology, Isfahan 84156-83111, Iran
| | - J A Tuszynski
- Department of Physics and Experimental Oncology, University of Alberta, Alberta T6G 2J1, Canada
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Yin B, Wang B, Rylander HG, Milner TE. Degradation in the degree of polarization in human retinal nerve fiber layer. J Biomed Opt 2014; 19:16001. [PMID: 24390374 PMCID: PMC3881105 DOI: 10.1117/1.jbo.19.1.016001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 12/02/2013] [Accepted: 12/04/2013] [Indexed: 05/21/2023]
Abstract
Using a fiber-based swept-source (SS) polarization-sensitive optical coherence tomography (PS-OCT) system, we investigate the degree of polarization (DOP) of light backscattered from the retinal nerve fiber layer (RNFL) in normal human subjects. Algorithms for processing data were developed to analyze the deviation in phase retardation and intensity of backscattered light in directions parallel and perpendicular to the nerve fiber axis (fast and slow axes of RNFL). Considering superior, inferior, and nasal quadrants, we observe the strongest degradation in the DOP with increasing RNFL depth in the temporal quadrant. Retinal ganglion cell axons in normal human subjects are known to have the smallest diameter in the temporal quadrant, and the greater degradation observed in the DOP suggests that higher polarimetric noise may be associated with neural structure in the temporal RNFL. The association between depth degradation in the DOP and RNFL structural properties may broaden the utility of PS-OCT as a functional imaging technique.
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Affiliation(s)
- Biwei Yin
- University of Texas at Austin, Departments of Electrical and Computer Engineering, 1 University Station C0803, Austin, Texas 78712
- Address all correspondence to: Biwei Yin, E-mail:
| | - Bingqing Wang
- University of Texas at Austin, Department of Biomedical Engineering, 1 University Station, C0800, Austin, Texas 78712
| | - Henry G. Rylander
- University of Texas at Austin, Department of Biomedical Engineering, 1 University Station, C0800, Austin, Texas 78712
| | - Thomas E. Milner
- University of Texas at Austin, Department of Biomedical Engineering, 1 University Station, C0800, Austin, Texas 78712
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