Calculations of Second Moments of NQR Signals for Explosive Materials

摘要

Calculations of the second moments of Nuclear Quadrupole Resonance (NQR) signalsare presented in this report. Numerical computations are performed for two explosive materials: cyclotrimethylene-trinitrarnine, RDX, and cyclotetramethylene, Beta-HMX. The report includes a discussion of vector and tensor analysis necessary for performing calculations in the nonorthonormal coordinate systems. The basic theory for calculations of second moments is described and the procedure for numerical computations is outlined. The listings of MATLABe programs are also included. calculations are performed for nuclei with spin I = 1 and asymmetric field gradient. For cases under consideration no external magnetic field is present. Calculations of the second moments include first order contributions due to dipolar interactions between completely equivalent nuclei and interactions between nuclei with the EFG tensors of the same magnitude but different orientation. The second order contributions from dipolar interactions between nitrogen and hydrogen nuclei are also considered.