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We studied luminescence accompanied an injection of the nitrogen-helium gas mixture after passing discharge into dense cold helium gas. Initially, when the experimental beaker was filled with superfluid helium and the nitrogen-helium gas was injected into bulk superfluid helium at T ≈ 1.5 K, the dominant band in the emission spectra was the α-group of nitrogen atoms. At these conditions, the nanoclusters of molecular nitrogen with high concentrations of stabilized nitrogen atoms were formed. When superfluid helium was evaporated from the beaker and the temperature at the bottom of the beaker was increased to T ≈ 20 K, we observed a drastic change in the luminescence spectra. The β-group of oxygen atoms was dominated in the luminescence spectra, and the emission of the α-group became small. At high temperatures (T ≈ 20 K), most of the nitrogen atoms recombine on the surface of N2 nanoclusters with the formation of excited nitrogen molecules. We explained the effect of the enhancement of β-group emission by effective energy transfer from excited nitrogen molecules to the stabilized impurity oxygen atom inside N2 nanoclusters.
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This content will become publicly available on July 7, 2026
Superfluid helium-4 in porous structures of neon-nitrogen nanoclusters as a target for low-mass dark matter detector
A new concept of three-phase projection chamber filled with a collection of neon-nitrogen nanoclusters immersed in superfluid helium-4 is proposed for detection light dark matter particles with low masses (0.1–10 Gev/c2). Such a time projection chamber includes a drift region within aerogel-like structure formed by neon-nitrogen nanoclusters filled by superfluid helium and a gas phase camera where electroluminescence takes place. The proposed concept combines the promising properties of liquid helium as a target material for direct detection of light dark matter particles such as high quenching factor, substantial scintillation light, high radiopurity, and high impedance to external vibration noise with the new ones determined by the properties of solid neon and nitrogen. The presence of highly porous impurity structure will enhance the primary scintillation signal (S1) due to light emission stimulated by interactions of metastable He2(a3Σu) molecules and He+ions with impurity nanoclusters. The signal of electrons produced by the recoil event (S2) and drifting in external electric field will get additional input due to energy stored in nitrogen atoms stabilized on the nanoclusters’ surface.
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- Award ID(s):
- 2104756
- PAR ID:
- 10648717
- Editor(s):
- Borghesani, Armando F
- Publisher / Repository:
- Frontiers in Detector Science and Technology
- Date Published:
- Journal Name:
- Frontiers in Detector Science and Technology
- Volume:
- 3
- ISSN:
- 2813-8031
- Subject(s) / Keyword(s):
- dark matter detection, time projection chamber (TPC), superfluid helium, nanoclusters, rare event searches
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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