Fissile Mass Estimation Using Delayed Gamma-Rays and Neutrons from Fast and Epithermal Induced Fissions

Year
2018
Author(s)
Aharon Ocherashvili - Nuclear Research Centre - Negev
Arie Beck - Nuclear Research Centre - Negev
Tatjana Bogucarska - Nuclear Security Unit, Institute of Transuranium Elements, Ispra
Jean Michel Crochemore - Nuclear Security Unit, Institute of Transuranium Elements, Ispra
Gay Heger - Nuclear Research Centre - Negev
David Michaeli - Nuclear Security Unit, Institute of Transuranium Elements, Ispra
Itamar Israelashvili - Nuclear Research Centre - Negev
Eric Roesgen - Nuclear Security Unit, Institute of Transuranium Elements, Ispra
Giovanni Varasano - Nuclear Security Unit, Institute of Transuranium Elements, Ispra
Bent Pedersen - Nuclear Security Unit, Institute of Transuranium Elements, Ispra
Abstract
We present a method with potential for the detection of special nuclear materials (SNM) in shielded containers which is both sensitive and applicable under field conditions. The method uses an external pulsed neutron source to induce fission in SNM and subsequent detection of the β-delayed γ rays and neutrons. The detectors surrounding the container under investigation are coaxial High Purity Germanium and 3He. This system can simultaneously provide gamma ray spectroscopy and neutron detection. Combined β-delayed γ rays neutrons can offer an increase in sensitivity for the detection of fissile materials. The paper describes laboratory tests with a configuration of two 3He slab detectors and coaxial High Purity Germanium surrounding the tested material in vicinity of the Pulsed Neutron Interrogation Test Assembly (PUNITA). Both the photon and neutron signatures for induced fission are observed. The methods used to isolate these signatures are described and demonstrated.