61 research outputs found
Thermal detection of single e-h pairs in a biased silicon crystal detector
We demonstrate that individual electron-hole pairs are resolved in a 1 cm
by 4 mm thick silicon crystal (0.93 g) operated at 35 mK. One side of the
detector is patterned with two quasiparticle-trap-assisted
electro-thermal-feedback transition edge sensor (QET) arrays held near ground
potential. The other side contains a bias grid with 20\% coverage. Bias
potentials up to 160 V were used in the work reported here. A fiber optic
provides 650~nm (1.9 eV) photons that each produce an electron-hole () pair in the crystal near the grid. The energy of the drifting charges
is measured with a phonon sensor noise 0.09 pair.
The observed charge quantization is nearly identical for 's or 's
transported across the crystal.Comment: 4 journal pages, 5 figure
Spatial imaging of charge transport in silicon at low temperature
We present direct imaging measurements of charge transport across a 1 cm × 1 cm × 4 mm crystal of high purity silicon (∼20 kΩ cm) at temperatures between 500 mK and 5 K. We use these data to determine the intervalley scattering rate of electrons as a function of the electric field applied along the ⟨111⟩ crystal axis, and we present a phenomenological model of intervalley scattering which explains the constant scattering rate seen at low-voltage for cryogenic temperatures. We also demonstrate direct imaging measurements of effective hole mass anisotropy, which is strongly dependent on both temperature and electric field strength. The observed effects can be explained by a warping of the valence bands for carrier energies near the spin-orbit splitting energy in silicon
Spatial Imaging of Charge Transport in Silicon at Low Temperature
We present direct imaging measurements of charge transport across a 1
cm 1 cm 4 mm crystal of high purity silicon (20
kcm) at temperatures between 500 mK and and 5 K. We use these data to
determine the intervalley scattering rate of electrons as a function of the
electric field applied along the crystal axis, and we
present a phenomenological model of intervalley scattering that explains the
constant scattering rate seen at low-voltage for cryogenic temperatures. We
also demonstrate direct imaging measurements of effective hole mass anisotropy,
which is strongly dependent on both temperature and electric field strength.
The observed effects can be explained by a warping of the valence bands for
carrier energies near the spin-orbit splitting energy in silicon.Comment: 5 Pages, 5 Figures. Submitted to Applied Physics Letter
Results from the Super Cryogenic Dark Matter Search (SuperCDMS) experiment at Soudan
We report the result of a blinded search for Weakly Interacting Massive
Particles (WIMPs) using the majority of the SuperCDMS Soudan dataset. With an
exposure of 1690 kg days, a single candidate event is observed, consistent with
expected backgrounds. This analysis (combined with previous Ge results) sets an
upper limit on the spin-independent WIMP--nucleon cross section of () cm at 46 GeV/. These results set the
strongest limits for WIMP--germanium-nucleus interactions for masses 12
GeV/
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