arXiv subjects

K. M. Dong

Publications and source records attributed to K. M. Dong.

2 recordsLinked to original sources

arXiv2026

Development and characterization of a wingless ICPC HPGe detector with thin amorphous-Ge contacts

High-purity germanium (HPGe) detectors with thin amorphous-germanium (a-Ge) contacts can provide bipolar charge blocking and surface passivation while minimizing contact-related inactive thickness. We report the fabrication and characterization of a p-type inverted coaxial point-contact (ICPC) HPGe detector using thin a-Ge contacts in a wingless geometry that avoids the protective wing structure used in our previous prototype. The detector was fabricated from a USD-grown, zone-refined HPGe crystal and has a mass of 20.0~g. At 77~K, it exhibited picoampere-scale leakage current and an operational depletion voltage of approximately 440~V. Gamma-ray spectroscopy yielded energy resolutions of 1.75~keV FWHM at 59.5~keV and 3.19~keV FWHM at 662~keV. The calibrated charge-injection method gave an absolute capacitance of 0.496~pF, with an estimated method-level relative uncertainty of 6--8\%, consistent with the 0.488~pF value obtained from electrostatic modeling with \texttt{SolidStateDetectors.jl}. With a $^{241}$Am source positioned inside the detector bore, the detector showed a source-correlated excess current and a broad degraded-alpha continuum centered near 3558~keV, demonstrating sensitivity to near-surface interactions. Because the source encapsulation, intervening materials, and near-surface charge-collection response were not independently characterized, the continuum is not used to infer a unique dead-layer thickness or energy-loss mechanism. The principal result is successful fabrication and stable sub-pF operation of a 20-g wingless thin-contact ICPC prototype.

physics.ins-det↗

arXiv2026

Fabrication and Characterization of p-type Inverted Coaxial Point Contact (ICPC) Detectors with a-Ge Dual-Blocking Contacts

We report the fabrication and characterization of two p-type inverted coaxial point contact (ICPC) high-purity germanium (HPGe) detectors, SAP16 and SAP17, produced from USD-grown crystals with net impurity concentrations of $\sim 3\times10^{10}\,\mathrm{cm^{-3}}$. Both devices employ \emph{thin} amorphous-germanium (a-Ge) dual-blocking contacts, implemented here for the first time on ICPC detectors, to provide bipolar charge blocking while limiting dead-layer thickness. Electrical tests at 76~K demonstrate stable operation with picoampere-level leakage currents and sub-pF capacitance: SAP17 reached $\sim 4.62$~pA at the maximum tested bias (500~V) and operated stably at 400~V with $C\simeq 0.503$~pF. \emph{Meanwhile,} SAP16 achieved superior spectroscopic performance, with energy resolutions of 2.42\% at 59.5~keV and 0.36\% at 662~keV. Gamma-ray spectroscopy with $^{241}$Am and $^{137}$Cs shows that modest geometric differences lead to measurable changes in depletion behavior and charge-collection uniformity, consistent with electrostatic modeling. Angular-response measurements further reveal pronounced directional sensitivity at 59.5~keV, whereas the 662~keV response is essentially isotropic over the measured range. These results validate thin a-Ge dual-blocking contacts for ICPC HPGe detectors and highlight geometry-driven trade-offs among leakage current, depletion, and energy resolution relevant to low-background and low-threshold applications.

physics.ins-det↗