Tomographic analysis of neutron and gamma pulse shape distributions from liquid scintillation detectors at Joint European Torus

Giacomelli, L.; Conroy, S.; Gorini, G.; Horton, L.D.; Murari, A.; Popovichev, S.; Syme, Don; Contributors, Jet

doi:10.1063/1.4864122

Cited by 14 publications

(6 citation statements)

References 19 publications

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“…These could instead be of major concerns for a scintillator. (iii) NE213 allows for n-γ pulse shape discrimination 41,42 which is not possible with a SDD, that, nevertheless, is fairly insensitive to γ -rays, as demonstrated by these measurements. Besides, γ -ray events mostly concentrate in the low energy part of the spectrum and can thus be discriminated by setting a proper low energy threshold in the PHS.…”

Section: Discussion and Outlookmentioning

confidence: 91%

Single crystal diamond detector measurements of deuterium-deuterium and deuterium-tritium neutrons in Joint European Torus fusion plasmas

Cazzaniga¹,

Sundén²,

Binda³

et al. 2014

Review of Scientific Instruments

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First simultaneous measurements of deuterium-deuterium (DD) and deuterium-tritium neutrons from deuterium plasmas using a Single crystal Diamond Detector are presented in this paper. The measurements were performed at JET with a dedicated electronic chain that combined high count rate capabilities and high energy resolution. The deposited energy spectrum from DD neutrons was successfully reproduced by means of Monte Carlo calculations of the detector response function and simulations of neutron emission from the plasma, including background contributions. The reported results are of relevance for the development of compact neutron detectors with spectroscopy capabilities for installation in camera systems of present and future high power fusion experiments.

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Section: Discussion and Outlookmentioning

confidence: 91%

Single crystal diamond detector measurements of deuterium-deuterium and deuterium-tritium neutrons in Joint European Torus fusion plasmas

Cazzaniga¹,

Sundén²,

Binda³

et al. 2014

Review of Scientific Instruments

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“…The spectrometers considered in this paper provide line integrated measurements and, as noted already, do not have spatial resolution. However, energy information of the spectrometers on a dual line of sight can be complemented by spatially resolved measurements of neutron emission by means of the JET neutron camera [57], which has been recently refurbished with a digital data acquisition [58,59]. The neutron camera can be used, for example, to validate predictions of the power deposition by the RF waves in the plasma volume.…”

Section: Validation Of Ab Initio Rf Heating Modelsmentioning

confidence: 99%

Dual sightline measurements of MeV range deuterons with neutron and gamma-ray spectroscopy at JET

Eriksson¹,

Nocente²,

Binda³

et al. 2015

Nucl. Fusion

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Observations made in a JET experiment aimed at accelerating deuterons to the MeV range by third harmonic radiofrequency (RF) heating coupled into a deuterium beam are reported. Measurements are based on a set of advanced neutron and gamma-ray spectrometers that, for the first time, observe the plasma simultaneously along vertical and oblique lines of sight. Parameters of the fast ion energy distribution, such as the high energy cut-off of the deuteron distribution function and the RF coupling constant, are determined from data within a uniform analysis framework for neutron and gamma-ray spectroscopy based on an one dimensional model and by a consistency check among the individual measurement techniques. A systematic difference is seen between the two lines of sight and is interpreted to originate from the sensitivity of the oblique detectors to the pitch-angle structure of the distribution around the resonance, which is not correctly portrayed within the adopted one dimensional model. A framework to calculate neutron and gamma-ray emission from a spatially resolved, two dimensional deuteron distribution specified by energy/pitch is thus developed and used for a first comparison with predictions from ab initio models of RF heating at multiple harmonics. The results presented in this paper are of relevance for the development of advanced diagnostic techniques for MeV range ions in high performance fusion plasmas, with applications to the experimental validation of RF heating codes and, more generally, to studies of the energy distribution of ions in the MeV range in high performance deuterium and deuterium-tritium plasmas.

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“…2.5 MeV neutrons are a good proxy for diagnosing the fast ion distribution in JET deuterium plasmas, since beam-target reactions are the dominant DD fusion reaction. The in-out asymmetry of the DD reaction rate profile in the poloidal plane can be best viewed by the vertical KN3 neutron camera, with nine channels looking down on the plasma from the top of the machine [34] as illustrated by figure 11. A DD reaction rate profile in (R, z) is calculated by ASCOT using parametrized fusion cross-sections [35].…”

Section: Comparison Of Ascot Results To Neutron Camera Measurementsmentioning

confidence: 99%

Effect of tungsten off-axis accumulation on neutral beam deposition in JET rotating plasmas

Koskela

Romanelli

Belo³

et al. 2015

Plasma Phys. Control. Fusion

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Evidence for low field side accumulation of tungsten is often observed in bolometry and soft x-ray emissivities of highly rotating JET ITER-like wall (ILW) plasmas. Poloidal variation of the density of high-Z impurities, such as tungsten, in the core of NBI heated plasmas is expected from neoclassical theory due to charge displacement and parallel electric field generated by the centrifugal force. We calculate the poloidally asymmetric distribution of tungsten using fluid equations and a 1D transport simulation with the JETTO/SANCO code. Peaking of tungsten on the outboard side of the plasma is found and verified with soft x-ray and bolometry measurements. We then study the effect of a poloidally asymmetric tungsten distribution on the distribution of the NBI heat source by simulations with the Monte Carlo code ASCOT. The simulations show that the poloidally asymmetric tungsten profile redistributes the fast NBI ions radially through shifting their ionization profile and poloidally through enhanced pitch-angle scattering at high energy. The amplitude of the redistribution is in the order of 10% for the highest n W /n e ratios of ∼10 −4 measured in recent JET H-mode plasmas. As a result of the scattering of the beam particles, the core heat deposition is changed less than 10%, which does not have a significant impact to the performance of JET plasmas. The modelling is in qualitative agreement with measurements by the vertical neutron camera that sees a broadening in the 2.5 MeV neutron profile when tungsten peaks on the outboard side of the plasma.

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Tomographic analysis of neutron and gamma pulse shape distributions from liquid scintillation detectors at Joint European Torus

Cited by 14 publications

References 19 publications

Single crystal diamond detector measurements of deuterium-deuterium and deuterium-tritium neutrons in Joint European Torus fusion plasmas

Single crystal diamond detector measurements of deuterium-deuterium and deuterium-tritium neutrons in Joint European Torus fusion plasmas

Dual sightline measurements of MeV range deuterons with neutron and gamma-ray spectroscopy at JET

Effect of tungsten off-axis accumulation on neutral beam deposition in JET rotating plasmas

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