  One trend in dark matter direct detection is the development of techniques
which will lower experimental thresholds and achieve sensitivity to light mass
dark matter particles. In doing so, it is necessary to have an understanding of
the low energy spectrum of the major background components. Geant4 has a number
of specialized low energy physics processes that can be implemented when
simulating an experimental geometry. To understand this low energy region for
the Super Cryogenic Dark Matter Search (SuperCDMS), a variety of these models
have been simulated and compared against theoretical calculations and SuperCDMS
calibration data. Most of the low energy processes include a more complete
description of the atomic structure, allowing us to observe the phenomenon of
Compton steps in the simulation. An important application of this low energy
background modeling is for the SuperCDMS low ionization threshold experiment
(CDMSlite). CDMSlite has reached world-leading sensitivities in the search for
low mass weakly interacting massive particle (WIMP) dark matter. Using
Neganov-Trofinov-Luke phonon amplification, CDMSlite has achieved a threshold
of less than 60 eV for electron recoils. The dark matter sensitivity of the
CDMSlite-Soudan data can be improved by understanding and modeling the
experimental backgrounds down to this threshold. Development of the machinery
for creating a low energy background model will also be useful in the future
SuperCDMS-SNOLAB experiment which will run multiple high voltage detectors in
CDMSlite mode.

Instrumentation and Detectors;Instrumentation and Methods for Astrophysics