Exploring Nonlinear Mechanical Behaviour of Rocks at LANCE
SMARTS - Spectrometer for Materials Research at Temperature and
Stress Atomic-scale stress-strain information obtained from the
neutron Rietveld data indicate that the strain experienced by
the crystalline quartz is ~1/5 of the macroscopic strain (the
rest taken up by the grain contacts and bonds in the rock). No
hints of nonlinearity whatsoever are evident in the neutron
data. Conclusion? The grain bond system (a small fraction of the
total rock) is responsible for all the peculiar quasi-static
nonlinearity we see. Beamlines at the LANSCE (Los Alamos Neutron
Science Center)/Lujan Center - LANSCE produces intense sources
of pulsed protons and spallation neutrons from a tungsten
target. Proton beam currents during all the experiments varied
from 100 to 110 µA. The Neutron Powder Diffractometer has the
unique capability of simultaneous high-Q Rietveld and pair-
density function analyses, enabling determination of the average
and local structures of compl