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Experimental verification of the flatness of response of a multi-BF3- counter neutron detection system

1973; Elsevier BV; Volume: 106; Issue: 2 Linguagem: Inglês

10.1016/0029-554x(73)90357-1

1878-3759

D.M. Crawford, B.W. Thomas, Klaus Böttcher, Robert Koch, H.H. Thies,

Nuclear reactor physics and engineering

The constancy of the detection efficiency η of a multi-BF3- counter neutron detection system built after a proposal by Thies1) was tested experimentally. In experiment (1) the neutron yield from 2D(γ,n) for bremsstrahlung peak energies 6 MeV < < E0 < 15.25 MeV was compared with yield values calculated with a theoretical 2D(γ,n)-cross-section. In experiment (2) - for the range 18.5 MeV < E0 < 27.7 MeV — the neutron yielld from a natural carbon target was measured with the multi-BF3-counter neutron detection system and concurrently by counting the 20.3 min positron activity induced in 11C. Finally the neutron yield from a carbon target enriched in 13C to 90% was measured, and the 12C(γ,n)-yield obtained from the natural carbon one by subtraction. By intercomparison of yields in experiments (1) and (2) the constancy of η was verified independently for the respective ranges of mean neutron energies 0.75 MeV< En < 1.7 MeV and 1.3 MeV < Ên < 4.6 MeV. Combining these results with those from an earlier experiment 2) it was verified that η is constant for 30 keV < Ên < 4.6 MeV, deviating by less than 1% from its average value in the range 1 MeV < Ên < 4.6. MeV.