(NEutron Detection System for Breakup of Unstable Nuclei with Large Acceptance)


NEBULA consists of neutron detectors (NEUT) and charged-particle veto detectors (VETO). Each module consists of plastic scintillator and two PMTs which are coupled to the ends of the scintillator via light guides. As of March, 2012, 120 NEUT modules and 24 VETO modules, each of which has the geometry shown in the Table below, are installed to form two sets of walls, each wall has a configuration 12 VETO modules + 30 NEUT modules x 2 Layers. We have also extra 24 VETO modules for future use. The detective area is 3.6m (Horizontal) x 1.8m, which corresponds to ±10 degrees in the horizontal direction and ±5 degrees in the vertical direction, when it is placed at 10m downstream from the target. The SAMURAI Superconducting spectrometer has a gap of 80 cm in order for neutrons to cover such large acceptance of NEBULA.

Plastic scintillatorBC-408 (Saint-Gobain)
NEUT: 12cm(H) x 12cm(T) x 180cm(V)
VETO: 32cm(H) x 1cm(T) x 190cm(V)
PMTR7724ASSY (Hamamatsu)
Effective area 3.6m(H) x 1.8m(V)
Electronics 32ch ADC V792 (CAEN)
32ch TDC V775 (CAEN)
16ch discriminator V895 (CAEN)
16ch 500ns logic delay (REPIC)
16ch 500ns analog cable delay & attenuator
SY1527LC + A1535SN (CAEN)