Monte Carlo simulation of active neutron interrogation system developed for detection of illicit materials А.Sh. Georgadze Kiev Institute for Nuclear Research a.sh.georgadze@gmail,com 2nd Jagelonian Symposium on Fundamental and Applied Subatomic Physics

Associated alpha-particle detection Probing with fast-neutron analysis (FNA) can excite gamma rays from carbon and oxygen found in excess in these explosives. To enhance the signal from the target and suppress background noise used a generator that produces back-to-back neutrons and α particles (a technique called associated-particle imaging) to identify the volume in which the neutron produces a gamma ray by tagging its time of emission and direction 

Explosive detection Using gamma lines after Nitrogen and Oxygen nuclei excitation Detect automatically 30 explosives High cost - 130000EURO !

Experiment in Ukraine Neutron generator ІNG-3 matrix 11×13 CsI (30×30 cm) with coded aperture mask Need repeat 5 times with changed mask. 150 см TNT

Chemical composition of explosives, drugs and common materials

Compact neutron generators Neutron flux 108 – 1014 n/s

Neutron pulses 10-20000/s

Cost effective gamma/neutron detector design Have applied block-detectors design (for PET) → less number of PMTs Photomultipliers PMT 9 х 9 Light sharing light guide Scintillation bars 30 bars 50 mm х 50 mm x 400 mm - plastic scintillator 10 bars 50 mm х 50 mm x 400 mm - CsI scintillator plastic scintillator - scatterer CsI (BGO) - absorber

Neutron captur gated detection principle Fast signal from proton γ n Gd p   8 MeV n t 25 ms Delayed signal

Scintillation bar enclosing Neutron captured by Gd [%] mean time until the capture [μs] 5  5 cm 88 25 55400 сm3 Plastic scintillator Mylar Gadolinium oxide containing film Light output 10000 ph/МеV

Compton imaging of gamma sources

GEANT4 simulation of Compton scattering Gamma-ray source Gray rays - gammas Green rays – electrons

Electronic collimation simulation Gamma ray beam direction

Electronic collimation

GEANT4 simulation of fissile material detection with neutron analysis Neutron generator Gamma/neutron detector Fissile or explosive material Distance to gamma/neutron detector 40 cm

Chemical compositions of the materials used for the simulation Explosives Composition 1. Ammonium nitrate H4N2O3 2. Ammonium picrate C8H8N4O7 3. RDX C3H8N8O8 4. Ethylenediamine C2H10N4O6 5. TNT C7H6N703 6. C4 C4H6N6O6 7. CL20 C8H8N12O12 8. Nitrocellulose C8H7N3O11 9. Nitroglycerine C3H8N3O3

Simulation of detected gamma-quanta and neutrons hitting detector - neutron generator flux - 108 n/s expositions 1 min Material number of neutrons gammas PLUTONIUM_DIOXIDE+ 4,80E+03 5,52E+04 URANIUM_OXIDE 4,20E+03 4,96E+04 G4_CELLULOSE NITRATE 2,51E+03 2,45E+04 G4_NYLON-11_RILSAN 2,40E+03 2,36E+04 AN 2,96E+04 4,12E+04 TNT 2,66E+04 RDX 3,00E+03 5,46E+04 CL20 2,80E+03 5,91E+04 No object 2,10E+03 2,06E+04

GEANT4 simulation of explosive detection with neutron analysis Blue rays – neutrons Red rays - gammas Neutron generator Gamma/neutron detector Explosive SiO2