is bonded chemically to the scintillator; some such tubes are visible on the roof section in Figure \[vetofigure2\]. To minimise loss of light within a scintillator bar, each piece has been wrapped along its length with PTFE sheet of high diffuse reflectivity, and then in black opaque sheet to provide light tightness. A reflector (aluminised Mylar film) is placed at the far end from the PMT to increase the light collection of the unit. All scintillator modules are 15 cm thick. Modules on the roof vary in length from $\sim$40 cm to $\sim$100 cm to form an approximate disc whereas the trapezoidal shaped barrel modules are all 100 cm in length.

The scintillator modules of the barrel surround individual 15 cm thick polypropylene sections that are loaded with 0.4% Gd by weight. The active and passive plastic sections together maintain the 30 cm hydrocarbon shielding thickness of the first science run. A single Gd-loaded polypropylene roof plug supports the 20 roof modules of scintillator. At 0.4% concentration of loading $>$99% of neutrons moderated to thermal energies undergo radiative capture on $^{157}$Gd (natural abundance 15.7%) which has an extraordinarily high capture cross section of 2.4$\times$10$^{5}$ barn [@gdcrosssec]. The benefit of using 