N. Hadad, D. Anderson, S. Désert, N. Hadad, S. Olsen, I. Sutton, G. Vehres, D. Adler, B. Ogg, D. Pierce
We present a summary description of the 8th annual international Design and Engineering of Neutron Instruments Meeting (DENIM) which was held in North Bethesda, MD, USA, September 17–19, 2019. DENIM VIII was organized by the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) in combination with the University of Maryland (UMD). DENIM specifically addresses the unique field of neutron instrument engineering, a subcategory of neutron scattering science. DENIM is organized by engineers for engineers who share openly about what works and what doesn’t work in the life cycle design of an instrument used to analyze materials with neutrons. DENIM is held under the patronage of the International Society of Neutron Instrument Engineers which was formed in 2017. At DENIM VIII, there were 3 keynote talks, 29 additional presentations and 13 posters (presented to the plenary in a poster slam session). Attendees toured the unique labs at NIST including the NCNR. Four parallel knowledge sharing sessions helped attendees explore mutual challenges and solutions in the areas of Instrument Installation Survey and Alignment, Electrical Grounding, Choppers and Velocity Selectors, and 3D Printing.
{"title":"8th Design and Engineering of Neutron Instruments Meeting in North Bethesda Maryland, USA 17–19 September 2019","authors":"N. Hadad, D. Anderson, S. Désert, N. Hadad, S. Olsen, I. Sutton, G. Vehres, D. Adler, B. Ogg, D. Pierce","doi":"10.3233/JNR-200174","DOIUrl":"https://doi.org/10.3233/JNR-200174","url":null,"abstract":"We present a summary description of the 8th annual international Design and Engineering of Neutron Instruments Meeting (DENIM) which was held in North Bethesda, MD, USA, September 17–19, 2019. DENIM VIII was organized by the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) in combination with the University of Maryland (UMD). DENIM specifically addresses the unique field of neutron instrument engineering, a subcategory of neutron scattering science. DENIM is organized by engineers for engineers who share openly about what works and what doesn’t work in the life cycle design of an instrument used to analyze materials with neutrons. DENIM is held under the patronage of the International Society of Neutron Instrument Engineers which was formed in 2017. At DENIM VIII, there were 3 keynote talks, 29 additional presentations and 13 posters (presented to the plenary in a poster slam session). Attendees toured the unique labs at NIST including the NCNR. Four parallel knowledge sharing sessions helped attendees explore mutual challenges and solutions in the areas of Instrument Installation Survey and Alignment, Electrical Grounding, Choppers and Velocity Selectors, and 3D Printing.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/JNR-200174","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48666146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A key element of the success of McStas is the component layer where users and developers alike are contributing to the description of new physical models and features. In McStas, components realise all physical elements of the simulated instrument from source via optics and samples to detector. In this second review paper of the McStas package, we present an overview of the component classes in McStas: sources, monitors, optics, samples, misc, and contrib. Within each component class we give thorough examples of high-quality components, including their algorithms and example use. We present two example instruments, one for a continuous source and one for a time-of-flight source, that together demonstrate the use of the main component classes. Finally, we give tips and instructions that will allow the reader to write good components and elucidate the pathway of contributing new components to McStas.
{"title":"McStas (ii): An overview of components, their use, and advice for user contributions","authors":"P. Willendrup, K. Lefmann","doi":"10.3233/JNR-200186","DOIUrl":"https://doi.org/10.3233/JNR-200186","url":null,"abstract":"A key element of the success of McStas is the component layer where users and developers alike are contributing to the description of new physical models and features. In McStas, components realise all physical elements of the simulated instrument from source via optics and samples to detector. In this second review paper of the McStas package, we present an overview of the component classes in McStas: sources, monitors, optics, samples, misc, and contrib. Within each component class we give thorough examples of high-quality components, including their algorithms and example use. We present two example instruments, one for a continuous source and one for a time-of-flight source, that together demonstrate the use of the main component classes. Finally, we give tips and instructions that will allow the reader to write good components and elucidate the pathway of contributing new components to McStas.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/JNR-200186","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45481819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present an overview of, and an introduction to, the general-purpose neutron simulation package McStas. We present the basic principles behind Monte Carlo ray-tracing simulations of neutrons performed in the package and present a few simple examples. We present the implementation of McStas, the status of the package and its use in the neutron community. Finally, we briefly discuss the planned development of the package.
{"title":"McStas (i): Introduction, use, and basic principles for ray-tracing simulations","authors":"P. Willendrup, K. Lefmann","doi":"10.3233/JNR-190108","DOIUrl":"https://doi.org/10.3233/JNR-190108","url":null,"abstract":"We present an overview of, and an introduction to, the general-purpose neutron simulation package McStas. We present the basic principles behind Monte Carlo ray-tracing simulations of neutrons performed in the package and present a few simple examples. We present the implementation of McStas, the status of the package and its use in the neutron community. Finally, we briefly discuss the planned development of the package.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/JNR-190108","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43561815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jakob Lassa, Magnus Egede Boggild, P. Hedegaard, K. Lefmann
It is generally known that counting statistics is not correctly described by a Gaussian approximation. Nevertheless, in neutron scattering, it is common practice to apply this approximation to the counting statistics; also at low counting numbers. We show that the application of this approximation leads to skewed results not only for low-count features, such as background level estimation, but also for its estimation at double-digit count numbers. In effect, this approximation is shown to be imprecise on all levels of count. Instead, a Multinomial approach is introduced as well as a more standard Poisson method, which we compare with the Gaussian case. These two methods originate from a proper analysis of a multi-detector setup and a standard triple axis instrument. We devise a simple mathematical procedure to produce unbiased fits using the Multinomial distribution and demonstrate this method on synthetic and actual inelastic scattering data. We find that the Multinomial method provide almost unbiased results, and in some cases outperforms the Poisson statistics. Although significantly biased, the Gaussian approach is in general more robust in cases where the fitted model is not a true representation of reality. For this reason, a proper data analysis toolbox for low-count neutron scattering should therefore contain more than one model for counting statistics.
{"title":"Multinomial, Poisson and Gaussian statistics in count data analysis","authors":"Jakob Lassa, Magnus Egede Boggild, P. Hedegaard, K. Lefmann","doi":"10.3233/jnr-190145","DOIUrl":"https://doi.org/10.3233/jnr-190145","url":null,"abstract":"It is generally known that counting statistics is not correctly described by a Gaussian approximation. Nevertheless, in neutron scattering, it is common practice to apply this approximation to the counting statistics; also at low counting numbers. We show that the application of this approximation leads to skewed results not only for low-count features, such as background level estimation, but also for its estimation at double-digit count numbers. In effect, this approximation is shown to be imprecise on all levels of count. Instead, a Multinomial approach is introduced as well as a more standard Poisson method, which we compare with the Gaussian case. These two methods originate from a proper analysis of a multi-detector setup and a standard triple axis instrument. We devise a simple mathematical procedure to produce unbiased fits using the Multinomial distribution and demonstrate this method on synthetic and actual inelastic scattering data. We find that the Multinomial method provide almost unbiased results, and in some cases outperforms the Poisson statistics. Although significantly biased, the Gaussian approach is in general more robust in cases where the fitted model is not a true representation of reality. For this reason, a proper data analysis toolbox for low-count neutron scattering should therefore contain more than one model for counting statistics.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-190145","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46429080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jurrian Bakker, Adam L. Washington, S. Parnell, A. A. van Well, C. Pappas, W. Bouwman
SESANS data analysis has been implemented in the SasView software package, allowing SESANS experiments to be analyzed using a numerical Hankel transformation of isotropic small-angle scattering (SAS) models. The error of the numerical approximation is three orders of magnitude below typical experimental errors. All advanced data fitting features of SasView (multi-model fitting, batch fitting, and simultaneous/constrained fitting) are now also available for SESANS and this is demonstrated by examples of fitting SAS models to SESANS measurements.
{"title":"Analysis of SESANS data by numerical Hankel transform implementation in SasView","authors":"Jurrian Bakker, Adam L. Washington, S. Parnell, A. A. van Well, C. Pappas, W. Bouwman","doi":"10.3233/jnr-200154","DOIUrl":"https://doi.org/10.3233/jnr-200154","url":null,"abstract":"SESANS data analysis has been implemented in the SasView software package, allowing SESANS experiments to be analyzed using a numerical Hankel transformation of isotropic small-angle scattering (SAS) models. The error of the numerical approximation is three orders of magnitude below typical experimental errors. All advanced data fitting features of SasView (multi-model fitting, batch fitting, and simultaneous/constrained fitting) are now also available for SESANS and this is demonstrated by examples of fitting SAS models to SESANS measurements.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-200154","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42445738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Kajimoto, M. Nakamura, K. Iida, K. Kamazawa, K. Ikeuchi, Y. Inamura, M. Ishikado
The elastic energy resolution, integrated intensity, and peak intensity of the direct-geometry neutron chopper spectrometer 4SEASONS at Japan Proton Accelerator Research Complex (J-PARC) were re-investigated. This was done with respect to the incident energy and the rotation speed of the Fermi chopper using incoherent scattering of vanadium and simple analytical formulas. The model calculations reproduced the observed values satisfactorily. The present work should be useful for estimating in instrument performance in experiments.
{"title":"Energy resolution and neutron flux of the 4SEASONS spectrometer revisited","authors":"R. Kajimoto, M. Nakamura, K. Iida, K. Kamazawa, K. Ikeuchi, Y. Inamura, M. Ishikado","doi":"10.3233/jnr-200146","DOIUrl":"https://doi.org/10.3233/jnr-200146","url":null,"abstract":"The elastic energy resolution, integrated intensity, and peak intensity of the direct-geometry neutron chopper spectrometer 4SEASONS at Japan Proton Accelerator Research Complex (J-PARC) were re-investigated. This was done with respect to the incident energy and the rotation speed of the Fermi chopper using incoherent scattering of vanadium and simple analytical formulas. The model calculations reproduced the observed values satisfactorily. The present work should be useful for estimating in instrument performance in experiments.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-200146","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47432669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Santoro, K. Andersen, D. Dijulio, E. Klinkby, T. Miller, D. Milstead, G. Muhrer, M.Stroble, A. Takibayev, L. Zanini, O. Zimmer
The European Spallation Source being constructed in Lund, Sweden will provide the user community with a neutron source of unprecedented brightness. By 2025, a suite of 15 instruments will be served by a high-brightness moderator system placed above the spallation target. The ESS infrastructure, consisting of the proton linac, the target station, and the instrument halls, allows for implementation of a second source below the spallation target. We propose to develop a second neutron source with a high-intensity moderator able to (1) deliver a larger total cold neutron flux, (2) provide high intensities at longer wavelengths in the spectral regions of Cold (4–10 Å), Very Cold (10–40 Å), and Ultra Cold (several 100 Å) neutrons, as opposed to Thermal and Cold neutrons delivered by the top moderator. Offering both unprecedented brilliance, flux, and spectral range in a single facility, this upgrade will make ESS the most versatile neutron source in the world and will further strengthen the leadership of Europe in neutron science. The new source will boost several areas of condensed matter research such as imaging and spin-echo, and will provide outstanding opportunities in fundamental physics investigations of the laws of nature at a precision unattainable anywhere else. At the heart of the proposed system is a volumetric liquid deuterium moderator. Based on proven technology, its performance will be optimized in a detailed engineering study. This moderator will be complemented by secondary sources to provide intense beams of Very- and Ultra-Cold Neutrons.
{"title":"Development of high intensity neutron source at the European Spallation Source","authors":"V. Santoro, K. Andersen, D. Dijulio, E. Klinkby, T. Miller, D. Milstead, G. Muhrer, M.Stroble, A. Takibayev, L. Zanini, O. Zimmer","doi":"10.3233/jnr-200159","DOIUrl":"https://doi.org/10.3233/jnr-200159","url":null,"abstract":"The European Spallation Source being constructed in Lund, Sweden will provide the user community with a neutron source of unprecedented brightness. By 2025, a suite of 15 instruments will be served by a high-brightness moderator system placed above the spallation target. The ESS infrastructure, consisting of the proton linac, the target station, and the instrument halls, allows for implementation of a second source below the spallation target. We propose to develop a second neutron source with a high-intensity moderator able to (1) deliver a larger total cold neutron flux, (2) provide high intensities at longer wavelengths in the spectral regions of Cold (4–10 Å), Very Cold (10–40 Å), and Ultra Cold (several 100 Å) neutrons, as opposed to Thermal and Cold neutrons delivered by the top moderator. Offering both unprecedented brilliance, flux, and spectral range in a single facility, this upgrade will make ESS the most versatile neutron source in the world and will further strengthen the leadership of Europe in neutron science. The new source will boost several areas of condensed matter research such as imaging and spin-echo, and will provide outstanding opportunities in fundamental physics investigations of the laws of nature at a precision unattainable anywhere else. At the heart of the proposed system is a volumetric liquid deuterium moderator. Based on proven technology, its performance will be optimized in a detailed engineering study. This moderator will be complemented by secondary sources to provide intense beams of Very- and Ultra-Cold Neutrons.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-200159","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70093148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We acknowledge Grant No. PGC-2018-099024-B-I00 from Spanish Ministry of Science Innovation and Universities and funding from the project I-COOP B20319. This work was performed within the world class Science and Innovation with Neutrons in Europe 2020 (“SINE2020”) project, funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 654000.
{"title":"Routines for optimizing neutron scattering instruments with McStas","authors":"V. Laliena, M. V. Alvarez, J. D. Campo","doi":"10.3233/jnr-190117","DOIUrl":"https://doi.org/10.3233/jnr-190117","url":null,"abstract":"We acknowledge Grant No. PGC-2018-099024-B-I00 from Spanish Ministry of Science Innovation and Universities and funding from the project I-COOP B20319. This work was performed within the world class Science and Innovation with Neutrons in Europe 2020 (“SINE2020”) project, funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 654000.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-190117","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42039937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Kiefer, L. Rossa, Frank Wutzler, Niklas Ektröm, Anders Pettersson, E. Faulhaber, Markus Zolliker
. The Sample Environment Communication Protocol (SECoP) serves as an international standard for the communication between sample environment equipment and the experiment control software at neutron and photon sources. It eases the integration of sample environment equipment supplied by external research groups and by industrial manufacturers. SECoP is designed to be simple, inclusive and self-describing. SECoP facilitates and structures the provision of metadata which is associated with sample environment equipment. Several existing implementations of SECoP support the development of SECoP-compatible sample environment control software. This article intro- duces SECoP Version 1.0, the first official version of SECoP published in September 2019. It was developed during the SINE2020 project in close cooperation with the International Society for Sample Environment. The complete specifications of SECoP Version 1.0 are available on GitHub.
{"title":"An introduction to SECoP – the sample environment communication protocol","authors":"K. Kiefer, L. Rossa, Frank Wutzler, Niklas Ektröm, Anders Pettersson, E. Faulhaber, Markus Zolliker","doi":"10.3233/jnr-190143","DOIUrl":"https://doi.org/10.3233/jnr-190143","url":null,"abstract":". The Sample Environment Communication Protocol (SECoP) serves as an international standard for the communication between sample environment equipment and the experiment control software at neutron and photon sources. It eases the integration of sample environment equipment supplied by external research groups and by industrial manufacturers. SECoP is designed to be simple, inclusive and self-describing. SECoP facilitates and structures the provision of metadata which is associated with sample environment equipment. Several existing implementations of SECoP support the development of SECoP-compatible sample environment control software. This article intro- duces SECoP Version 1.0, the first official version of SECoP published in September 2019. It was developed during the SINE2020 project in close cooperation with the International Society for Sample Environment. The complete specifications of SECoP Version 1.0 are available on GitHub.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-190143","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41549633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Klotz, T. Hansen, E. Lelièvre-Berna, L. Amand, J. Maurice, C. Payre
Paris-Edinburgh (PE) presses are nowadays the dominant high pressure devices for neutron scattering in the 10 GPa range and above. Here, we present developments of gasket-anvil assemblies with 30% improved pressure performance and considerably increased lifetime compared to the currently used “single-toroidal” anvils, and giving nevertheless a similar signal-to-background ratio. We also present an improved Bridgman seal package which makes the low-temperature operation of the PE press significantly more reliable. A systematic investigation of background sources in the “equatorial” scattering geometry is reported.
{"title":"Advances in the use of Paris-Edinburgh presses for high pressure neutron scattering","authors":"S. Klotz, T. Hansen, E. Lelièvre-Berna, L. Amand, J. Maurice, C. Payre","doi":"10.3233/jnr-190120","DOIUrl":"https://doi.org/10.3233/jnr-190120","url":null,"abstract":"Paris-Edinburgh (PE) presses are nowadays the dominant high pressure devices for neutron scattering in the 10 GPa range and above. Here, we present developments of gasket-anvil assemblies with 30% improved pressure performance and considerably increased lifetime compared to the currently used “single-toroidal” anvils, and giving nevertheless a similar signal-to-background ratio. We also present an improved Bridgman seal package which makes the low-temperature operation of the PE press significantly more reliable. A systematic investigation of background sources in the “equatorial” scattering geometry is reported.","PeriodicalId":44708,"journal":{"name":"Journal of Neutron Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2020-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3233/jnr-190120","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47154425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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