Measurement of angle correlated spectrum of two neutrons emitted from (n, 2n) reaction by coincidence detection technique with a pencil-beam DT neutron source

R and D activities at the fusion neutronics source (FNS) facility of Japan Atomic Energy Agency (JAEA) are reviewed for the period of April 2004-March 2006. Using a pencil-beam of D-T neutrons at FNS, the (n, 2n) reaction cross sections including the triple differential cross section (TDX), the angle double-differential cross section (ADDX), the angular differential cross section (ADX) and total (n, 2n) reaction cross section (TOX) for beryllium are measured by the coincidence detection method. Precise emission-angle correlated spectra of the two neutrons from the (n, 2n) reaction of beryllium are obtained for the first time. (T.I.)