Machine learning technique to improve anti-neutrino detection efficiency for the ISMRAN experiment

The Indian Scintillator Matrix for Reactor Anti-Neutrino detection - ISMRAN experiment aims to detect electron anti-neutrinos ((nu) over bar (e)) emitted from a reactor via inverse beta decay reaction (IBD). The setup, consisting of 1 ton segmented Gadolinium foil wrapped plastic scintillator array, is planned for remote reactor monitoring and sterile neutrino search. The detection of prompt positron and delayed neutron from IBD will provide the signature of (nu) over bar (e) event in ISMRAN. The number of segments with energy deposit (N-bars) and sum total of these deposited energies are used as discriminants for identifying prompt positron event and delayed neutron capture event. However, a simple cut based selection of above variables leads to a low (nu) over bar (e) signal detection efficiency due to overlapping region of N-bars and sum energy for the prompt and delayed events. Multivariate analysis (MVA) tools, employing variables suitably tuned for discrimination, can be useful in such scenarios. In this work we report the results from an application of artificial neural network - the multilayer perceptron (MLP), particularly the Bayesian extension - MLPBNN, to the simulated signal and background events in ISMRAN. The results from application of MLP to classify prompt positron events from delayed neutron capture events on Hydrogen, Gadolinium nuclei and also from the typical reactor gamma-ray and fast neutron backgrounds is reported. An enhanced efficiency of similar to 91% with a background rejection of similar to 73% for prompt selection and an efficiency of similar to 89% with a background rejection of similar to 71% for the delayed capture event, is achieved using the MLPBNN classifier for the ISMRAN experiment.