1. Method for 14-MeV neutron yield determination using a MPR neutron spectrometer Göran Ericsson, H.Sjöstrand, S.Conroy, E.Andersson Sundén, A.Combo 1, N.Cruz 1, M.Gatu Johnson, L.Giacomelli, W.Glasser, G.Gorini 2, H.Henriksson, A.Hjalmarsson, N.Kronborg, J.Källne, A.Murari 3, S.Popovichev 3, P.Ricardo 1, E.Ronchi, J.Sousa 1, M.Tardocchi 2, 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 Scattered events Direct events (C)

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

6. MCNP model layout Horizontal cut Vertical cut

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

8. Results TTEDTE1

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 (p reference ) = 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