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Method for 14-MeV neutron yield determination using a MPR neutron spectrometer

Method for 14-MeV neutron yield determination using a MPR neutron spectrometer. Göran Ericsson, H.Sjöstrand, S.Conroy,

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Method for 14-MeV neutron yield determination using a MPR neutron spectrometer

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  1. Method for 14-MeV neutronyield determination using a MPR neutron spectrometer Göran Ericsson, H.Sjöstrand, S.Conroy, E.Andersson Sundén, A.Combo1, N.Cruz1, M.Gatu Johnson, L.Giacomelli, W.Glasser, G.Gorini2, H.Henriksson, A.Hjalmarsson, N.Kronborg, J.Källne, A.Murari3, S.Popovichev3, P.Ricardo1, E.Ronchi, J.Sousa1,M.Tardocchi2, M.Weiszflog, and EFDA-JET contributors Dept. of Neutron Research, Uppsala University, Sweden EURATOM-VR Association 1) Associação EURATOM/IST, Centro de Fusão Nuclear, Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal. 2)INFM, Dept. of Physics, Univ. of Milano-Bicocca and Istituto di Fisica del Plasma, EURATOM-ENEA-CNR Association, Milan, Italy 3) JET, Culham Science Center, Oxfordshire, Culham, UK

  2. Neutron yield determination • Tokamak • Neutron camera • Absolutely calibrated spectrometer

  3. Neutron emission profile • Δp is derived from neutron camera data • Δp = ±0.15 • Uncertainty in Δp is normally around 0.01 • Only the shape of the neutron emission profile is needed Neutron emission profile reconstruction from neutron camera data

  4. MPR efficiency and count rate • Efficiency calculated from first principles • Depends on well known quantities • Spectrometer able to separate direct and scattered events • 2.5% uncertainty Direct events (C) Scattered events

  5. Scattering Schematic Plasma (neutron source) Attenuation 20% Targetfoil Transmission 13% Neutron trajectories Inscatter (port) 2% Backscatter < 1% Direct Inscatter (collimator) 7% Collimation Vacuum vessel

  6. MCNP model layout Horizontal cut Vertical cut

  7. Profile dependence on the scattered flux • Scattering and transmission is profile dependent (small corrections) • Optimal LOS should minimizes s, t, Δp and Δst

  8. Results TTE DTE1

  9. Systematic uncertainties • Uncertainties are uncorrelated and well defined • Efficiency (e) = 2.5% • Scattering, attenuation and transmission (t)+ (s) + (a) = 4% • Neutron emission profile and LOS (preference)= 3% • Background corrections (C) = 0 - 3% • Resulting systematic error = 5.5-6.5%

  10. Summary • A method to determine the 14-MeV n rate (power) using an absolutely calibrated spectrometer and a neutron camera has been developed • The method provides the yield with <6.5% systematic error • The method has been validated with data from JET’s DTE1 and TTE campaigns

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