Article history: Received 21 February 2014 Received in revised form 23 August 2014 Accepted 30 October 2014 Available online 18 November 2014
Keywords: Neutron background Liquid organic scintillator Neutron-scatter camera CRY Angular distribution
abstract
The cosmic-ray-induced neutron background at ground level has been measured and simulated in conjunction with EJ-309 organic liquid scintillators with an approximate deposited energy range of 0.5–6MeV. Specifically, the pulse height distributions, net neutron count rates, and angular dependences were obtained. The simulations were carried out using the Monte Carlo transport code MCNPX-PoliMi combined with the (Cosmic-Ray Shower Generator) CRY source subroutine that returns secondary particles produced by cosmic rays. A scaling formula from literature was also implemented in the simulation. The angular dependence of the neutron count rate was measured by collimating the liquid scintillator with polyethylene to attain 181 angular resolution from 01 downwards to 721 horizontally. The neutron count rate was measured to be 23.1071.69h1 sr1 at 01, and 7.2070.78h1 sr1 at 721. The simulations and measurements compare well and show similar cosine anisotropy for the angular distribution. The study thus shows that the neutron background response in detector systems can be efficientlyand accurately simulated using the procedures described.