Optimization of moderator assembly for neutron flux measurement: experimental and theoretical approaches

  • Abdul Waheed
  • Nawab Ali
  • Muzahir A. Baloch
  • Aziz A. Qureshi
  • Eid A. Munem
  • Muhammad Usman Rajput
  • Tauseef Jamal
  • Wazir Muhammad


A moderator of paraffin wax assembly has been demonstrated where its thickness can be optimized to thermalize fast neutrons. The assembly is used for measuring fast neutron flux of a neutron probe at different neutron energies, using BF3 (Φ1″ and 2″) and 3He(Φ0.5″) neutron detectors. The paraffin wax thickness was optimized at 6 cm for the neutron probe which contains an Am–Be neutron source. The experimental data are compared with Monte Carlo simulation results using MCNP5 version 1.4. Neutron flux comparison and neutron activation techniques are used for measuring neutron flux of the neutron probe to validate the optimum paraffin moderator thickness in the assembly. The neutron fluxes are measured at (1.17 ± 0.09) × 105 and (1.19 ± 0.1) × 105 n/s, being in agreement with the simulated values. The moderator assembly can easily be utilized for essential requirements of neutron flux measurements.


Am–Be and 252Cf neutron sources BF3 & 3He detectors Paraffin wax Neutron flux Monte Carlo simulation 



The authors gratefully acknowledge services provided by Mr. Usman Ali, RPL, CIIT, in the fabrication of mechanical assembly and safe handling of neutron sources.


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Copyright information

© Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Chinese Nuclear Society, Science Press China and Springer Science+Business Media Singapore 2017

Authors and Affiliations

  • Abdul Waheed
    • 1
  • Nawab Ali
    • 2
  • Muzahir A. Baloch
    • 3
  • Aziz A. Qureshi
    • 1
  • Eid A. Munem
    • 4
  • Muhammad Usman Rajput
    • 2
  • Tauseef Jamal
    • 5
  • Wazir Muhammad
    • 6
  1. 1.Radiation Physics Laboratory, Physics DepartmentCOMSATS Institute of Information Technology (CIIT)IslamabadPakistan
  2. 2.Physics DivisionPakistan Institute of Nuclear Science and Technology (PINSTECH)IslamabadPakistan
  3. 3.Department of Physics, College of ScienceMajmaah UniversityAl-ZulfiSaudi Arabia
  4. 4.School of PhysicsUniversity Science MalaysiaGelugorMalaysia
  5. 5.DCISPakistan Institute Engineering and Applied Sciences (PIEAS)IslamabadPakistan
  6. 6.Health Physics Division (HPD)Pakistan Institute of Nuclear Science and Technology (PINSTECH)IslamabadPakistan

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