| Contacts | Location map | DE  

Laboratory for High Energy Physics


Physics Applications in Security

A promising new technology proposed for the vast area of security applications is the Gamma Nuclear Resonant Absorbtion (GNRA) radiography. It assumes the use of high-resolution tracking detectors with a substantial content of Nitrogen as gamma-to-charged particle conversion medium. An appealing approach that we are developing is to use liquid Argon time projection chambers (TPC) for this purpose, doped with liquid Nitrogen to a concentration that provides high gamma conversion efficiency in the resonant band on one side, and sufficient charge transport and collection performance on the other. Nitrogen nucleus excited by the gamma absorbed in the resonant band relaxes to the Carbon nucleus with emission of the proton. Gamma outside of the resonant band are mainly visible through Compton scattering in Argon-Nitrogen mixture.
The high spatial resolution detector, able to distinguish such protons from Compton electrons is therefore able to see the gamma rays intensity ditribution specifically in the resonant band of Nitrogen absorbtion spectrum. On the other side same reaction happens with gammas in the inspected object. This allows to see the contrast of the Nitrogen content in this object. Such information in combination with the density contrast from the out-of-resonance gammas allows efficiently detect some specific substances, in particular many explosive materials. We develop a TPC on the mixture of liquid Argon and Nitrogen, which is a very promising detector for such application.

Universität Bern | Laboratory for High Energy Physics | Sidlerstrasse 5 | CH-3012 Bern | Tel: +41 (0)31 631 40 64 | Fax: +41 (0)31 631 44 87
© Universität Bern | Imprint