Position reconstruction in a liquid xenon scintillation chamber for low-energy nuclear recoils and γ-rays

A position reconstruction algorithm was implemented for a liquid xenon scintillation camera aiming to reduce the uncertainty in the measurement of the energy of nuclear recoils from neutron scattering. The algorithm is based on the maximum likelihood (ML) technique. The performance of the algorithm was assessed both with simulated and experimental data. A resolution of σxy=6.7 mm was measured with 122 keV γ-rays at the bottom of the chamber. For 10 keV γ-rays simulated events, a resolution of σxy⩽20 mm was obtained for 80% of the active volume of the detector. By means of the position reconstruction, the uncertainty of the nuclear recoil energy in the neutron scattering experiment was reduced by a factor of 2–3, depending on the energy.