Velocity-space observation regions of high-resolution two-step reaction gamma-ray spectroscopy. (21st August 2015)

• Record Type: Journal Article
• Authors: Salewski, M.; Nocente, M.; Gorini, G.; Jacobsen, A.S.; Kiptily, V.G.; Korsholm, S.B.; Leipold, F.; Madsen, J.; Moseev, D.; Nielsen, S.K.; Rasmussen, J.; Stejner, M.; Tardocchi, M
• Other Names: collab.
• Is Part Of: Nuclear fusion. Volume 55:Number 9(2015:Sep.)
• Publication Date: 2015-08-21
• Subjects: gamma-ray spectroscopy -- energetic particles -- tokamaks; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/0029-5515/55/9/093029
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: High-resolution γ -ray spectroscopy (GRS) measurements resolve spectral shapes of Doppler-broadened γ -rays. We calculate weight functions describing velocity-space sensitivities of any two-step reaction GRS measurements in magnetized plasmas using the resonant nuclear reaction 9 Be( α, n γ ) 12 C as an example. The energy-dependent cross sections of this reaction suggest that GRS is sensitive to alpha particles above about 1.7 MeV and highly sensitive to alpha particles at the resonance energies of the reaction. Here we demonstrate that high-resolution two-step reaction GRS measurements are not only selective in energy but also in pitch angle. They can be highly sensitive in particular pitch angle ranges and completely insensitive in others. Moreover, GRS weight functions allow rapid calculation of γ -ray energy spectra from fast-ion distribution functions, additionally revealing how many photons any given alpha-particle velocity-space region contributes to the measurements in each γ -ray energy bin.