Light, MeV-scale dark matter (DM) is an exciting DM candidate that is undetectable by current experiments. A germanium (Ge) detector utilizing internal charge amplification for the charge carriers created by the ionization of impurities is a promising new technology with experimental sensitivity for detecting MeV-scale DM. We analyze the physics mechanisms of the signal formation, charge creation, charge internal amplification, and the projected sensitivity for directly detecting MeV-scale DM particles. We present a design for a novel Ge detector at helium temperature (∼ 4 K) enabling ionization of impurities from DM impacts. With large localized E-fields, the ionized excitations can be accelerated to kinetic energies larger than the Ge bandgap at which point they can create additional electron-hole pairs, producing intrinsic amplification to achieve an ultra-low energy threshold of ∼ 0.1 eV for detecting low-mass DM particles in the MeV scale. Correspondingly, such a Ge detector with 1 kg-year exposure will have high sensitivity to a DM-nucleon cross section of ∼ 5 × 10 −45 cm 2 at a DM mass of ∼ 10 MeV/c 2 and a DM-electron cross section of ∼ 5 × 10 −46 cm 2 at a DM mass of ∼ 1 MeV/c 2 .
A glassy carbon electrode (GCE) was covalently modified by 4‐phosphatephenyl (4‐PP). Sensing paracetamol (PCT) via linear sweep voltammetry in sulfuric buffer solution of pH 1.02 at 36.8 °C, the 4‐PP‐modified GCE showed high electrochemical sensitivity and long reusability. PCT‐loaded poly(vinyl alcohol) (PVA) nanofibers were prepared by electrospinning. Based on the calibration curve of PCT on the 4‐PP‐modified GCE, the PCT release process from the nanofibers was electrochemically monitored in real time via two routes. The results showed that the covalently modified GCE can be repeatedly used as real‐time electrochemical monitoring platform for drug release from drug‐loaded nanofibers in the long term.
The photoluminescence (PL) characteristics of CdSe quantum dots (QDs) infiltrated into inverse opal SiO2 photonic crystals (PCs) are systemically studied. The special porous structure of inverse opal PCs enhanced the thermal exchange rate between the CdSe QDs and their surrounding environment. Finally, inverse opal SiO2 PCs suppressed the nonlinear PL enhancement of CdSe QDs in PCs excited by a continuum laser and effectively modulated the PL characteristics of CdSe QDs in PCs at high temperatures in comparison with that of CdSe QDs out of PCs. The final results are of benefit in further understanding the role of inverse opal PCs on the PL characteristics of QDs.
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