Open Access
March 2014 Testing for shielding of special nuclear weapon materials
Kung-Sik Chan, Jinzheng Li, William Eichinger, Erwei Bai
Ann. Appl. Stat. 8(1): 553-576 (March 2014). DOI: 10.1214/13-AOAS704


Nuclear-weapon-material detection via gamma-ray sensing is routinely applied, for example, in monitoring cross-border traffic. Natural or deliberate shielding both attenuates and distorts the shape of the gamma-ray spectra of specific radionuclides, thereby making such routine applications challenging. We develop a Lagrange multiplier (LM) test for shielding. A strong advantage of the LM test is that it only requires fitting a much simpler model that assumes no shielding. We show that, under the null hypothesis and some mild regularity conditions and as the detection time increases, LM test statistic for (composite) shielding is asymptotically Chi-square with the degree of freedom equal to the presumed number of shielding materials. We also derive the local power of the LM test. Extensive simulation studies suggest that the test is robust to the number and nature of the intervening materials, which owes to the fact that common intervening materials have broadly similar attenuation functions.


Download Citation

Kung-Sik Chan. Jinzheng Li. William Eichinger. Erwei Bai. "Testing for shielding of special nuclear weapon materials." Ann. Appl. Stat. 8 (1) 553 - 576, March 2014.


Published: March 2014
First available in Project Euclid: 8 April 2014

zbMATH: 06302247
MathSciNet: MR3192002
Digital Object Identifier: 10.1214/13-AOAS704

Keywords: Gamma ray detection , homeland security , Lagrange multiplier test , local power , multicollinearity , Poisson regression

Rights: Copyright © 2014 Institute of Mathematical Statistics

Vol.8 • No. 1 • March 2014
Back to Top