Nuclear resonance fuorescence drug inspection


Haoyang Lan, Tan Song, Xingde Huang, Shengqiang Zhao, Jianliang Zhou, Zhichao Zhu, Yi Xu, Dimiter L. Balabanski, Wen Luo [ ]

This study is a simulation work to explore the drug inspection based on the laser-Compton scattering (LCS) γ-ray source, for example the variable energy Gamma (VEGA) system at ELI-NP.
The smuggling of contraband is one of the biggest threats to public health, human welfare and national security, and there is an increasing challenge to prevent illicit drug smuggling across borders and seaports. Currently, the illicit drug trafficking becomes more and more rampant. However, the existing techniques in-and-of-themselves are not sufficient to identify the illicit drugs rapidly and accurately.
In the present study, combining nuclear resonance fluorescence (NRF) spectroscopy and the element (or isotope) ratio approach, a novel inspection method that can simultaneously reveal the elemental (or isotopic) composition of the illicit drugs, such as widely abused methamphetamine, cocaine, heroin, ketamine and morphine, is presented. In the NRF spectroscopy, the nuclei are excited by the induced photon beam from the LCS γ-ray source, and the measurement of the characteristic energies of the emitted γ-ray from the distinct energy levels in the excited nuclei provides "fingerprints" of the interested elements in the illicit drugs. The element ratio approach is further used to identify drug elemental composition.
In practical, the Monte Carlo simulations are carried out to realize this proposed method. It is shown that four NRF peaks from the nuclei 12C, 14N and 16O can be detected with high significance of 7-24σ using an induced photon beam flux of 1011. The ratio of 14N/12C and/or 16O/12C for illicit drugs inspected are then extracted using the element ratio approach. Good agreement between the present simulation results and the theoretical calculations is found. The feasibility to detect the illicit drugs, inside a 15-mm-thick iron shielding or surrounded by thin benign materials, is further investigated. It is indicated that, using the state-of-the-art γ-ray source with high intensity and energy tenability, for example the VEGA system at ELI-NP, the proposed method has a great potential for identifying drugs and explosives in a realistic measurement time.

The element ratios of oxygen to carbon (a) and nitrogen to carbon (b). Coca., Meth., Keta., Hero. And Caff. are abbreviations for the drugs Cocaine, Methamphetamine, Ketamine, Heroin and Caffeine, respectively.