1Overview
Lithium-6 glass (commonly designated GS20 and related cerium-activated silicate glasses) is a thermal-neutron scintillator. Detection works through the ⁶Li(n,α)³H reaction: a captured thermal neutron releases an alpha particle and a triton with about 4.78 MeV of shared kinetic energy, and the cerium-activated glass matrix converts that energy into a light pulse. Because the glass is a rigid, non-hygroscopic solid, 6Li-glass detectors are mechanically robust and need no hermetic sealing, which simplifies rugged field and security deployments.
The trade-off is light output. 6Li-glass produces only a few percent of the light of NaI(Tl), and its gamma response overlaps the neutron signal, so pulse-height discrimination between neutrons and gamma background is limited compared with dual-mode crystals such as CLYC or CLLBC. Where the requirement is straightforward thermal-neutron counting in a tough, sealed-free package, 6Li-glass remains a cost-effective and reliable choice.
Berkeley Nucleonics supplies 6Li-glass in custom sizes and assembled detector formats with PMT or SiPM readout. Enriched (95% ⁶Li) and natural-lithium variants are available depending on whether maximum neutron sensitivity or gamma-response studies are the goal.
2Specifications
Values below are representative of cerium-activated lithium silicate glass (GS20-class) drawn from standard published material properties. Confirm against the specific glass grade and enrichment before specifying.
| Parameter | Value | Notes |
|---|---|---|
| Material | ⁶Li-enriched cerium-activated silicate glass | GS20 and related grades |
| Density | 2.5-2.6 g/cm³ | Low Z; light, rugged |
| Emission maximum | ~395 nm | Ce³⁺ activator emission; matches bialkali PMT and SiPM |
| Decay constant | ~60-75 ns | Fast relative to alkali-halide scintillators |
| Refractive index | ~1.55-1.56 | Glass matrix |
| Relative light yield | ~4-6 (NaI(Tl)=100) | Low; ~6000 photons per neutron capture |
| ⁶Li enrichment | up to ~95% | Enriched for maximum thermal-neutron sensitivity; natural-Li also available |
| Neutron reaction | ⁶Li(n,α)³H, Q = 4.78 MeV | Thermal-neutron capture |
| Hygroscopic | No | No hermetic seal required |
3Performance
The neutron capture peak appears at a well-defined pulse height set by the 4.78 MeV reaction Q-value, which makes thermal-neutron events identifiable against the lower-amplitude gamma continuum. Gamma rejection is achieved primarily through a pulse-height threshold rather than pulse-shape discrimination, since the scintillation decay is similar for both event types. For environments with high gamma backgrounds, neutron/gamma separation is more limited than with CLYC or 6Li-loaded composite detectors.
4Typical Applications
- Thermal-neutron detection: portal monitors, search and survey instruments, special nuclear material screening
- Homeland security: neutron channels in radiation portal monitors and handheld systems
- Neutron beam diagnostics: flux monitoring at research reactors and spallation sources
- Well logging and industrial gauging: rugged, non-hygroscopic neutron sensing
- He-3 replacement: a solid-state alternative for thermal-neutron counting where He-3 supply is constrained
5Available Configurations
6Li-glass is supplied as discs, plates, and custom-machined elements, with PMT or SiPM readout. Enrichment level, thickness, and active area are selected to balance neutron efficiency against gamma sensitivity. Contact the ScintIQ team to specify geometry and enrichment.
| Parameter | Standard / Typical |
|---|---|
| Form factors | Discs, plates, machined custom elements (verify size list) |
| Readout | PMT or SiPM |
| Enrichment options | Enriched ⁶Li (~95%) or natural lithium |
| Sealing | None required (non-hygroscopic) |
6Request a Quote
6Li-glass detectors are quoted as custom assemblies. Contact the ScintIQ applications team with your neutron energy range, required efficiency, gamma background, and readout preference.
Talk to a ScintIQ Engineer
The BNC applications team can specify the right 6Li-glass geometry, enrichment, and readout for your neutron measurement environment.