The paper discusses the energy response of a single crystal stilbene and two liquid scintillator detectors, BC501 and EJ309 to a range of neutrons and gamma energies generated using a 1.7MV Tandetron accelerator at IIT Kanpur. Stilbene is a solid-state composite organic detector can be used as an alternative choice for combined neutron-gamma detection. Studies have shown that stilbene’s light output response is similar to BC501. Works have also claimed a linear response of stilbene to neutrons for energies less than 5 MeV. In this work, neutrons are generated using the IIT-Kanpur 1.7MV Tandetron using C(Li⁷,n) reaction. The threshold energy of the reaction and the target thickness are determined by Monte Carlo simulations. Next, we measure the pulse height distribution of various neutron energies incident on stilbene, BC501 and EJ309 of the same dimensions. The response of all the organic crystals of the study to neutrons using the Tandetron is performed on energy spanning the fission neutron energy range to fast neutron energy range. A general-purpose Monte Carlo simulation kit, GEANT4, is used for simulating the reaction and detector response behaviour. Stilbene shows 38% lower energy response than that of EJ309 and BC501 shows 11% lower energy response from EJ309 for the entire neutron spectrum. These responses are consistent as the number density of hydrogen of the same mass of stilbene, BC501 is 38% and 11% lower than EJ309, respectively. GEANT4 simulation allows a detailed analysis of detector response physics for the advancement of detector development for nuclear security applications.

1. S. T. Paul et al., “Measurement of neutron spectra generated from bombardment of 4 to 24 MeV protons on a thick ⁹Be target and estimation of neutron yields,” Rev. Sci. Instrum., vol. 85, no. 6, pp. 4 – 11, Jun. 2014.
   DOI: 10.1063/1.4880202
   PMid: 24985813
2. What is Neutron Therapy?, Fermilab, Batavia (IL), USA.
   Retrieved from: https://www-bd.fnal.gov/ntf/what_is/index.html
   Retrieved on: May 6, 2019
3. IBC, 1.7 MV TANDETRON ACCELERATOR FACILITY, Indian Institute of Technology Kanpur, Kanpur, India.
4. Retrieved from: https://www.iitk.ac.in/ibc/
   Retrieved on: May 7, 2019
5. D. L. Chichester, Production and Applications of Neutrons using Particle Accelerators, Idaho National Laboratory, Idaho (ID), USA, 2009.
   Retrieved from: https://inldigitallibrary.inl.gov/sites/sti/sti/6302373.pdf
   Retrieved on: May 7, 2019
6. Geant4 Book For Application Developers, CERN, Geneva, Switzerland.
   Retrieved from: http://cern.ch/geant4-userdoc/UsersGuides/ForApplicationDeveloper/html/ Retrieved on: May 10, 2019
7. B. H. Kang, S. K. Lee, Y. K. Kim, N. Z. Galunov, G. D. Kim, “Evaluation of a composite stilbene for the fast neutron detection,” in Proc. IEEE Nucl. Sci. Symp. Med. Imaging Conf. (NSS/MIC), Knoxville (TN), USA, 2010.
   DOI: 10.1109/NSSMIC.2010.5873729
8. CAS DataBase, CAS, Columbus (OH), USA.
   Retrieved from: https://www.chemicalbook.com/ChemicalProductProperty_EN_CB4331036.htm/
   Retrieved on: May 11, 2019
9. BC-501, BC-501A, BC-519 Liquid Scintillators, Saint Gobain, Courbevoie, France.
   Retrieved from: https://www.crystals.saint-gobain.com/sites/imdf.crystals.com/files/documents/bc501-501a-519-data-sheet.pdf
   Retrieved on: May 11, 2019
10. EJ-301, EJ-309, Eljen Technology, Sweetwater (TX), USA.
    Retrieved from: https://eljentechnology.com/products/liquid-scintillators/ej-301-ej-309/
    Retrieved on: May 11, 2019
11. O. Tarasenko, N. Galunov, N. Karavaeva, I. Lazarev, V. Panikarskaya, “Stilbene composite scintillators as detectors of fast neutrons emitted by a ²⁵²Cf source,” Radiat. Meas., vol. 58, pp. 61 – 65, Nov. 2013.
    DOI: 10.1016/j.radmeas.2013.08.005
12. Geant4 User`s Guide for Application Developers, CERN, Geneva, Switzerland, 2016.
    Retrieved from: https://gentoo.osuosl.org/distfiles/BookForAppliDev-4.10.03.pdf
    Retrieved on: Apr. 10, 2019
13. J. Iwanowska et al., “Neutron/gamma discrimination properties of composite scintillation detectors,” J. Instrum., vol. 6, Jul. 2011.
    DOI: 10.1088/1748-0221/6/07/P07007
14. J. Iwanowska et al., “Neutron/gamma discrimination properties of composite scintillation detectors,” J. Instrum., vol. 6, Jul. 2011.
    DOI: 10.1088/1748-0221/6/07/P07007