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Sahlberg A, Eriksson J, Conroy S, Ericsson G, Hägg L, Giacomelli L, Belli F. Forward modeling of pile-up events in liquid scintillator detectors for neutron emission spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:083502. [PMID: 34470438 DOI: 10.1063/5.0052260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 07/09/2021] [Indexed: 06/13/2023]
Abstract
When using liquid scintillator detectors to measure the neutron emission spectrum from fusion plasmas, the problem of pile-up distortion can be significant. Because of the large neutron rates encountered in many fusion experiments, some pile-up distortion can remain even after applying traditional pile-up elimination methods, which alters the shape of the measured light-yield spectrum and influences the spectroscopic analysis. Particularly, pile-up events appear as a high-energy tail in the measured light-yield spectrum, which obfuscates the contribution that supra-thermal ions make to the energy spectrum. It is important to understand the behavior of such "fast ions" in fusion plasmas, and it is hence desirable to be able to measure their contribution to the neutron spectrum as accurately as possible. This paper presents a technique for incorporating distortion from undetected pile-up events into the analysis of the light-yield spectrum, hence compensating for pile-up distortion. The spectral contribution from undetected pile-up events is determined using Monte Carlo methods and is included in the spectroscopic study as a pile-up component. The method is applied to data from an NE213 scintillator detector at JET and validated by comparing with results from the time-of-flight spectrometer TOFOR, which is not susceptible to pile-up distortion. Based on the results, we conclude that the suggested analysis method helps counteract the problem of pile-up effects and improves the possibilities for extracting accurate fast-ion information from the light-yield spectrum.
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Affiliation(s)
- A Sahlberg
- Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden
| | - J Eriksson
- Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden
| | - S Conroy
- Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden
| | - G Ericsson
- Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden
| | - L Hägg
- Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden
| | - L Giacomelli
- Istituto per la Scienza e la Tecnologia dei Plasmi, Consiglio Nazionale delle Ricerche, 20125 Milano, Italy
| | - F Belli
- ENEA C. R. Frascati, Dipartimento FSN, via E. Fermi 45, 00044 Frascati (Roma), Italy
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Järleblad H, Stagner L, Salewski M, Eriksson J, Benjamin S, Madsen B, Nocente M, Rasmussen J, Schmidt BS. Fast-ion orbit sensitivity of neutron emission spectroscopy diagnostics. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:043526. [PMID: 34243421 DOI: 10.1063/5.0040696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/23/2021] [Indexed: 06/13/2023]
Abstract
Fast ions in fusion plasmas often leave characteristic signatures in the plasma neutron emission. Measurements of this emission are subject to the phase-space sensitivity of the diagnostic, which can be mapped using weight functions. In this paper, we present orbit weight functions for the TOFOR and NE213 neutron diagnostics at the Joint European Torus, mapping their phase-space sensitivity in 3D orbit space. Both diagnostics are highly sensitive to fast ions that spend a relatively large fraction of their orbit transit times inside the viewing cone of the diagnostic. For most neutron energies, TOFOR is found to be relatively sensitive to potato orbits and heavily localized counter-passing orbits, as well as trapped orbits whose "banana tips" are inside the viewing cone of TOFOR. For the NE213-scintillator, the sensitivity is found to be relatively high for stagnation orbits.
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Affiliation(s)
- H Järleblad
- Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - L Stagner
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - M Salewski
- Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - J Eriksson
- Department of Physics and Astronomy, Uppsala University, 751 20 Uppsala, Sweden
| | - S Benjamin
- Mathematical Sciences Institute, Australian National University, Canberra ACT 2601, Australia
| | - B Madsen
- Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - M Nocente
- Department of Physics, University of Milano-Bicocca, 20126 Milano, Italy
| | - J Rasmussen
- Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - B S Schmidt
- Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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Giacomelli L, Belli F, Binda F, Conroy SW, Eriksson J, Milocco A, Popovicev S, Syme DB. Neutron emission spectroscopy of D plasmas at JET with a compact liquid scintillating neutron spectrometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10I113. [PMID: 30399806 DOI: 10.1063/1.5038549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 06/11/2018] [Indexed: 06/08/2023]
Abstract
Neutron emission spectroscopy is a diagnostic technique that allows for energy measurements of neutrons born in nuclear reactions. The JET tokamak fusion experiment (Culham, UK) has a special role in this respect as advanced spectrometers for 2.5 MeV and 14 MeV neutrons have been developed here for the first time for measurements of the neutron emission spectrum from D and DT plasmas with unprecedented accuracy. Twin liquid scintillating neutron spectrometers were built and calibrated at the Physikalisch-Technische Bundesanstalt (PTB) (Braunschweig, Germany) and installed on JET in the recent years with tangential-equatorial (KM12) and vertical-radial (KM13) view lines, with the latter only recently operational. This article reports on the performance of KM12 and on the development of the data analysis methods in order to extract physics information upon D ions kinematics in JET auxiliary-heated D plasmas from 2.5 MeV neutron measurements. The comparison of these results with the correspondents from other JET neutron spectrometers is also presented: their agreement allows for JET unique capability of multi-lines of sight neutron spectroscopy and for benchmarking other 14 MeV neutron spectrometers installed on the same lines of sight in preparation for the DT experimental campaign at JET.
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Affiliation(s)
- L Giacomelli
- Istituto di Fisica del Plasma "P. Caldirola," CNR, Milano, Italy
| | - F Belli
- Dipartimento FSN, ENEA CR Frascati, Roma, Italy
| | - F Binda
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - S W Conroy
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - J Eriksson
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - A Milocco
- Dipartimento di Fisica "G. Occhialini," Università degli Studi di Milano-Bicocca, Milano, Italy
| | - S Popovicev
- CCFE, Culham Science Centre, Abingdon, United Kingdom
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Salewski M, Nocente M, Jacobsen AS, Binda F, Cazzaniga C, Eriksson J, Geiger B, Gorini G, Hellesen C, Kiptily VG, Koskela T, Korsholm SB, Kurki-Suonio T, Leipold F, Moseev D, Nielsen SK, Rasmussen J, Schneider PA, Sharapov SE, Stejner M, Tardocchi M, JET Contributors, ASDEX Upgrade Team, EUROfusion MST1 Team. Bayesian Integrated Data Analysis of Fast-Ion Measurements by Velocity-Space Tomography. FUSION SCIENCE AND TECHNOLOGY 2018. [DOI: 10.1080/15361055.2017.1380482] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- M. Salewski
- Technical University of Denmark, Department of Physics, Kgs. Lyngby, Denmark
| | - M. Nocente
- University of Milano Bicocca, Department of Physics, Milano, Italy
- Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, Milano, Italy
| | | | - F. Binda
- Uppsala University, Department of Physics and Astronomy, Uppsala, Sweden
| | - C. Cazzaniga
- ISIS Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, United Kingdom
| | - J. Eriksson
- Uppsala University, Department of Physics and Astronomy, Uppsala, Sweden
| | - B. Geiger
- Max-Planck-Institut für Plasmaphysik, Garching, Germany
| | - G. Gorini
- University of Milano Bicocca, Department of Physics, Milano, Italy
- Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, Milano, Italy
| | - C. Hellesen
- Uppsala University, Department of Physics and Astronomy, Uppsala, Sweden
| | - V. G. Kiptily
- CCFE, Culham Science Centre, Abingdon, Oxon, United Kingdom
| | - T. Koskela
- Aalto University, Department of Applied Physics, Aalto, Finland
- NERSC, Lawrence Berkeley National Laboratory, Berkeley, California
| | - S. B. Korsholm
- Technical University of Denmark, Department of Physics, Kgs. Lyngby, Denmark
| | - T. Kurki-Suonio
- Aalto University, Department of Applied Physics, Aalto, Finland
| | - F. Leipold
- Technical University of Denmark, Department of Physics, Kgs. Lyngby, Denmark
| | - D. Moseev
- Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
| | - S. K. Nielsen
- Technical University of Denmark, Department of Physics, Kgs. Lyngby, Denmark
| | - J. Rasmussen
- Technical University of Denmark, Department of Physics, Kgs. Lyngby, Denmark
| | | | - S. E. Sharapov
- CCFE, Culham Science Centre, Abingdon, Oxon, United Kingdom
| | - M. Stejner
- Technical University of Denmark, Department of Physics, Kgs. Lyngby, Denmark
| | - M. Tardocchi
- Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, Milano, Italy
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Jacobsen AS, Binda F, Cazzaniga C, Eriksson J, Hjalmarsson A, Nocente M, Salewski M, Tardini G. Velocity-space sensitivities of neutron emission spectrometers at the tokamaks JET and ASDEX Upgrade in deuterium plasmas. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:073506. [PMID: 28764505 DOI: 10.1063/1.4991651] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Future fusion reactors are foreseen to be heated by the energetic alpha particles produced in fusion reactions. For this to happen, it is important that the energetic ions are sufficiently confined. In present day fusion experiments, energetic ions are primarily produced using external heating systems such as neutral beam injection and ion cyclotron resonance heating. In order to diagnose these fast ions, several different fast-ion diagnostics have been developed and implemented in the various experiments around the world. The velocity-space sensitivities of fast-ion diagnostics are given by so-called weight functions. Here instrument-specific weight functions are derived for neutron emission spectrometry detectors at the tokamaks JET and ASDEX Upgrade for the 2.45 MeV neutrons produced in deuterium-deuterium reactions in deuterium plasmas. Using these, it is possible to directly determine which part of velocity space each detector observes.
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Affiliation(s)
- A S Jacobsen
- Max-Planck-Institut für Plasmaphysik, Garching, Germany
| | - F Binda
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - C Cazzaniga
- ISIS Facility, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot OX11 0QX, United Kingdom
| | - J Eriksson
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - A Hjalmarsson
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - M Nocente
- Dipartimento di Fisca "G. Occhialini," Università degli Studi di Milano-Bicocca, Milano, Italy
| | - M Salewski
- Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark
| | - G Tardini
- Max-Planck-Institut für Plasmaphysik, Garching, Germany
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Rebai M, Giacomelli L, Milocco A, Nocente M, Rigamonti D, Tardocchi M, Camera F, Cazzaniga C, Chen ZJ, Du TF, Fan TS, Giaz A, Hu ZM, Marchi T, Peng XY, Gorini G. Response function of single crystal synthetic diamond detectors to 1-4 MeV neutrons for spectroscopy of D plasmas. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11D823. [PMID: 27910604 DOI: 10.1063/1.4960490] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A Single-crystal Diamond (SD) detector prototype was installed at Joint European Torus (JET) in 2013 and the achieved results have shown its spectroscopic capability of measuring 2.5 MeV neutrons from deuterium plasmas. This paper presents measurements of the SD response function to monoenergetic neutrons, which is a key point for the development of a neutron spectrometer based on SDs and compares them with Monte Carlo simulations. The analysis procedure allows for a good reconstruction of the experimental results. The good pulse height energy resolution (equivalent FWHM of 80 keV at 2.5 MeV), gain stability, insensitivity to magnetic field, and compact size make SDs attractive as compact neutron spectrometers of high flux deuterium plasmas, such as for instance those needed for the ITER neutron camera.
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Affiliation(s)
- M Rebai
- University of Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
| | - L Giacomelli
- Istituto di Fisica del Plasma "P. Caldirola," CNR, Milano, Italy
| | - A Milocco
- University of Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
| | - M Nocente
- University of Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
| | - D Rigamonti
- University of Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
| | - M Tardocchi
- Istituto di Fisica del Plasma "P. Caldirola," CNR, Milano, Italy
| | - F Camera
- INFN Milano, Via Celoria 16, 20133 Milano, Italy
| | - C Cazzaniga
- Istituto di Fisica del Plasma "P. Caldirola," CNR, Milano, Italy
| | - Z J Chen
- School of Physics, State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
| | - T F Du
- School of Physics, State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
| | - T S Fan
- School of Physics, State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
| | - A Giaz
- INFN Milano, Via Celoria 16, 20133 Milano, Italy
| | - Z M Hu
- School of Physics, State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
| | - T Marchi
- Department of Physics and Astronomy, Instituut voor Kern- en Stralingsfysica, KU Leuven, Leuven, Belgium
| | - X Y Peng
- School of Physics, State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China
| | - G Gorini
- University of Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
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Nocente M, Cazzaniga C, Tardocchi M, Binda F, Eriksson J, Giacomelli L, Muraro A, Rebai M, Sharapov S, Gorini G. Fast ion energy distribution from third harmonic radio frequency heating measured with a single crystal diamond detector at the Joint European Torus. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:103501. [PMID: 26520949 DOI: 10.1063/1.4931755] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Neutron spectroscopy measurements with a single crystal diamond detector have been carried out at JET, for the first time in an experiment aimed at accelerating deuterons to MeV energies with radio frequency heating at the third harmonic. Data are interpreted by means of the expected response function of the detector and are used to extract parameters of the highly non-Maxwellian distribution function generated in this scenario. A comparison with observations using a time of flight and liquid scintillator neutron spectrometers is also presented. The results demonstrate the capability of diamond detectors to contribute to fast ion physics studies at JET and are of more general relevance in view of the application of such detectors for spectroscopy measurements in the neutron camera of next step tokamak devices.
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Affiliation(s)
- M Nocente
- EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom
| | - C Cazzaniga
- EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom
| | - M Tardocchi
- EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom
| | - F Binda
- EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom
| | - J Eriksson
- EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom
| | - L Giacomelli
- EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom
| | - A Muraro
- EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom
| | - M Rebai
- EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom
| | - S Sharapov
- EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom
| | - G Gorini
- EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, United Kingdom
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