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Two-dimensional solid state gaseous detector for thermal and cold neutrons is created. The detector has active area of 128 x 128 mm 2 , 10 B neutron converter, and gas chamber with thin windows. The resistive charge-division readout is applied to determine the neutron position. The detector was tested using W-Be photoneutron source at the Institute for Nuclear Research, Moscow. The detector efficiency is estimated as ~4% at neutron wavelength λ = 1.82 Å and 8% at λ = 8 Å. The efficiency of the background detection was less than 10 -5 of that for thermal neutrons. The resulting pulse height resolution and the spatial resolution are estimated as ~15% and ~2.5 mm, respectively.

Determination of energy of nn-singlet virtual state in d+ 2 H  p+ p +n+n reactionAbstract The nn final state interaction has been investigated in d+ 2 H(pp) S +(nn) S p+p+n+n reaction going through a formation and breakup of singlet diproton and dineutron in the intermediate state.In the kinematically complete experiment performed at Ed =15 MeV two proton and neutron were detected at angles close to those of emission of (pp) S and (nn) S systems. Simulation of the reaction showed that the shape of neutron energy (timing) spectrum depends on εnn − the energy of virtual 1 S0 state of nn-system. The most likely value εnn = 0.076 ± 0.006MeV was obtained by fitting procedure using the experimental data and simulations. This low value of εnn evidently indicates on effective enhancement of nn-interaction in the intermediate state of studied reaction.