Study of γ-ray background from cosmic muon induced neutrons

• Published in: The European physical journal. A, Hadrons and nuclei Hadrons and nuclei, 2019-08, Vol.55 (8), p.1-8, Article 136
• Main Authors: Krishnamoorthy, H., Gupta, G., Garai, A., Mazumdar, A., Reza, A., Pal, S., Pethuraj, S., Nanal, V., Shrivastava, A., Pillay, R. G.
• Format: Article
• Language: English
• Subjects: Background radiation; Beta decay; Fast neutrons; Hadrons; Heavy Ions; Muons; Neutrons; Nuclear Fusion; Nuclear Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Regular Article - Experimental Physics
• ISSN: 1434-6001; 1434-601X
• DOI: 10.1140/epja/i2019-12822-3

. The contribution to γ -ray background from secondary neutrons, originating from cosmic muon interactions in Pb-Cu composite shield, has been measured via ( n , n γ ) reactions in Cu and Ge. The minimization of background plays a key role in improving the sensitivity of rare event experimental searches like neutrinoless double beta decay and neutron background is often a major concern. It is important to understand secondary neutron production from cosmic muons, especially in materials like Cu and Pb, which often form a part of the detector or shields. The direct contribution of fast neutrons generated from cosmic muon interactions to the γ -ray background via ( n , n γ ) reactions is investigated for the first time. Measurements are carried out in the low background HPGe detector setup, TiLES, using Pb-Cu composite shield as target material for muon interactions. Simulations have been carried out with GEANT4.10.00 and GEANT4.10.05, each with two different Physics lists. The observed intensities of ( n , n γ ) for Cu are significantly under-predicted by GEANT4.10.00, while GEANT4.10.05 shows good agreement with the experimental data.