Method for 14-MeV neutron yield determination using a MPR neutron spectrometer
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Method for 14-MeV neutron yield 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
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Neutron yield determination
(1 )
(1 )
n
n n reference
nreference
CFe
F Y p p s a t
CYe p p s a t
•Tokamak•Neutron camera•Absolutely calibrated spectrometer
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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
(1 )referencen
CYe s a tp p
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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
(1 )nreference
Yp p
Ce s a t
Scattered events
Direct events (C)
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Scattering Schematic
Transmission 13%
Attenuation 20%
(1 )nreference
CYe p p s a t
Direct
Backscatter < 1%Inscatter (port) 2%
Target foil
Collimation
Vacuum vessel
Plasma (neutron source)
Neutron trajectories
Inscatter (collimator) 7%
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MCNP model layoutHorizontal cut Vertical cut
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Scattering and transmission is profile dependent (small corrections)
Optimal LOS should minimizes s, t, Δp and Δst
Profile dependence on the scattered flux
Profile dependence along Z=0
0,2
0,4
0,6
0,8
1
1,2
1,4
240 260 280 300 320 340 360
R (cm)
Rel
ativ
e co
ntrib
utio
n
Transmission
Portscattering
Backscattering
1 1nreference
CYe p p a s stt
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ResultsTTE DTE1
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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%
1 1nreference
CYe p p a s t st
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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