Neutron Time-of-Flight Measurements Initiated with 25-keV Deuterons*

Neutron time-of-flight (nTOF) measurements have been completed using d-d fusion reactions produced by 25 keV deuterons.  Deuterons produced using the SUNY Geneseo 30 kV Peabody Scientific Duoplasmatron ion source are focussed onto thick deuterated polyethylene films producing fusion products.  In the laboratory coordinate system, 2.566 MeV neutrons detected by a BC-412 plastic scintillator at 39° correspond to 0.699 MeV ³He ions detected by a surface barrier detector (SBD) placed at 135°. At these low energies, the charged particle spectra have little to no background. Timing signals from the SBD preamplifier initiate a start signal and the associated timing signal from the photomultiplier tube initiates the stop signal.  By placing the scintillator at various distances from the target, the time-of-flight spectra can be used to determine an experimental value for the neutron energy, and this provides confirmation of the method. Using this nTOF technique, the neutron response for different scintillation detectors can be determined.