title: Neutron spectrometer for ITER using silicon detectors.
abstract: High resolution neutron spectrometers provide information about plasma parameters at existing fusion experiments. Such a system may also be employed at ITER. Proton recoil telescopes have classically been used to detect neutrons with good energy resolution but poor efficiency. Using annular silicon detectors, it is possible to greatly increase the solid angle coverage and hence improve efficiency. Based on a simulation (MCNPX) study, the scaling of energy resolution, efficiency, and time to determine an ion temperature to 10% accuracy on foil thickness and detector location is shown. The latter quantity is used to determine the optimum foil thickness and detector geometry for specific plasma temperatures. For a 20 keV deuterium-tritium (DT) plasma, 5.3% resolution with efficiency of 2.9x10(-4) n cm(2) is attainable using the available detectors. This gives a temperature measurement with 10% accuracy in 1.1 ms for a neutron flux of 2x10(9) n cm(-2). Multiple detectors can be used to further increase the efficiency if needed. A system of this kind could be tested in a future DT campaign at, for example, JET.
authors.affiliation: Department of Physics and Astronomy, Uppsala University, EURATOM-VR, Uppsala 75120, Sweden.
authors.forename: Sean W
authors.initials: SW
authors.lastname: Conroy
authors.forename: Matthias
authors.initials: M
authors.lastname: Weiszflog
authors.forename: Erik
authors.initials: E
authors.lastname: Andersson-Sunden
authors.forename: Goran
authors.initials: G
authors.lastname: Ericsson
authors.forename: Maria
authors.initials: M
authors.lastname: Gatu-Johnson
authors.forename: Carl
authors.initials: C
authors.lastname: Hellesen
authors.forename: Emanuel
authors.initials: E
authors.lastname: Ronchi
authors.forename: Henrik
authors.initials: H
authors.lastname: Sjostrand