NTL amplification in a SuperCDMS-style detector fabricated from a University of South Dakota-grown germanium crystal
Abstract
Neganov-Trofimov-Luke (NTL) amplification enables eV-sub-keV detection thresholds for low-mass dark-matter and coherent elastic neutrino-nucleus scattering experiments. We evaluated two University of South Dakota (USD)-grown germanium crystals fabricated as SuperCDMS-style four-channel athermal-phonon detectors and operated near 10 mK. The crystals had electrically active impurity concentrations near 1010 ^−3 and etch-pit densities of $300−7000~\mathrm^-2$. Contact-free biasing produced no resolvable amplification. However, after depositing a 600 nm aluminum bias contact, Detector~2 exhibited clear voltage-dependent NTL gain. The reconstructed channel-B energy increased from approximately 3.9 keV at 0 V to 34.9 keV at 40 V, corresponding to an 8.9-fold enhancement. Statistical centroid uncertainties were below 0.3%, while low-bias fits yielded effective prompt- and NTL-phonon response coefficients of (6.77±0.82)% and (4.77±0.20)%, respectively, excluding systematic uncertainties. These results demonstrate the feasibility of USD-grown germanium for SuperCDMS-style high-voltage phonon detectors and highlight the importance of both crystal quality and contact fabrication in achieving NTL amplification.
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BibTeX
@misc{mei2026amplification,
title = {{NTL amplification in a SuperCDMS-style detector fabricated from a University of South Dakota-grown germanium crystal}},
author = {Dongming Mei and Gerardo Gonzalez and William Baker and Mark Platt and Nader Mirabolfathi},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.29973},
eprint = {2610.29973},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.29973},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - NTL amplification in a SuperCDMS-style detector fabricated from a University of South Dakota-grown germanium crystal
AU - Dongming Mei
AU - Gerardo Gonzalez
AU - William Baker
AU - Mark Platt
AU - Nader Mirabolfathi
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2610.29973
UR - https://arxiv.org/abs/2610.29973
AB - Neganov-Trofimov-Luke (NTL) amplification enables eV-sub-keV detection thresholds for low-mass dark-matter and coherent elastic neutrino-nucleus scattering experiments. We evaluated two University of South Dakota (USD)-grown germanium crystals fabricated as SuperCDMS-style four-channel athermal-phonon detectors and operated near 10 mK. The crystals had electrically active impurity concentrations near 10^10 ^−3 and etch-pit densities of $300−7000~\mathrm^-2$. Contact-free biasing produced no resolvable amplification. However, after depositing a 600 nm aluminum bias contact, Detector~2 exhibited clear voltage-dependent NTL gain. The reconstructed channel-B energy increased from approximately 3.9 keV at 0 V to 34.9 keV at 40 V, corresponding to an 8.9-fold enhancement. Statistical centroid uncertainties were below 0.3%, while low-bias fits yielded effective prompt- and NTL-phonon response coefficients of (6.77±0.82)% and (4.77±0.20)%, respectively, excluding systematic uncertainties. These results demonstrate the feasibility of USD-grown germanium for SuperCDMS-style high-voltage phonon detectors and highlight the importance of both crystal quality and contact fabrication in achieving NTL amplification.
ER -