Looking for the best possible geometry for NEDA  Optimization of the volume of the detectors  Highest efficiency  Lowest cross-talk probability Granularity Modularity Different materials We took into account:

Definitions: The Cluster method Each pair of detectors is checked whether they fit to the drdt gate. If one detector is recognized as having the scattered event from the current cluster is added to that cluster. The number of cluster gives the number of neutrons detected. The drdt gate dr is the distance between the weight centers of two fired detectors. dt is the time difference between the moments of threshold exceedance of each detector, separately.

Definitions: Efficiency Clean 1n and 2n efficiency is the number of clusters which fit to drdt gate, in case the emitted neutron multiplicity is one and two, respectively. 1n -> 2n misinterpretation probability is the probability to treat 1n events as 2n. It means that is the ratio of the number of clusters which do not fit to the drdt gate to the total number of neutrons were shot.

Definitions: The drdt gate An example for the drdt gate (Staircase geometry):

Definitions: The neutron source: Neutron were shot in energies sampled from a 252 Cf source. (see plot) Threshold: 50 keV ee threshold has been considered for the light output

FlatZigzag 1 mDistance from the source1 m 169Granularity l Total Volume 507 l 3 l Unit Volume 3 l 1n Eff. BC501A9.08 %7.33 %BC501A BC %5.82 %BC πSolid Angle Coverage0.60 π

Staircase 1πStaircase 2π 1n Eff. BC501A15.97 %31 %BC501A BC %24 %BC537 1 mDistance from the source1 m 163Granularity l Total Volume 1065 l 3 l Unit Volume 3 l 1 πSolid Angle Coverage2 π

Spherical N180The Neutron Wall 0.50 mDistance from the source0.51 m 45Granularity l Total Volume 150 l 4.5 l Unit Volume 3 l 1n Eff. BC501A15.57 %15 %BC501A BC %N/ABC537 1 πSolid Angle Coverage2 π

Spherical 1πSpherical 2π 1 mDistance from the source1 m 326Granularity l Total Volume 1212 l 2 l Unit Volume 2 l 1n Eff. BC501A19.25 %37 %BC501A BC %29.35 %BC537 1 πSolid Angle Coverage1 π

Distance /radius Granularity Total Volume (L) Cell Volume (L) Solid Angle (π) Material Efficiency (1n) Flat1 m BC501A9.90 % BC % Zigzag1 m BC501A7.33 % BC % Stairs 1π1 m BC501A15.54 % BC % Stairs 2π1 m ~2 BC501A31 % BC53724 % Spherical N m BC501A15.57 % BC % Sperhical 1π1 m BC501A19.25 % BC % Sperhical 2π1 m BC501A37 % BC % NWall0.51 m50150~31 BC501A15 % BC537N/A