Speaker
Description
Observing neutrinoless double beta decay ($0\nu\beta\beta$) is critical for understanding whether neutrinos are Majorana particles, meaning they are their own antiparticles. Detecting the event would also provide insights into the origin of neutrino mass and help explain the matter-antimatter imbalance in the universe. Such a discovery would have a major impact on physics and cosmology.
The KamLAND-Zen experiment is currently the most sensitive search for $0\nu\beta\beta$ decay, using liquid scintillator with dissolved $\mathrm{^{136}Xe}$ in a detector located 1,000 m underground. It holds the strictest limit on the $0\nu\beta\beta$ half-life, and its successor, KamLAND2-Zen, is in development.
A key challenge for KamLAND2-Zen is long-lived spallation background (LLBG), radioactive nuclei created by cosmic muon spallations with $\mathrm{^{136}Xe}$. These nuclei cannot be removed before operation and are difficult to filter out, posing a major issue for $0\nu\beta\beta$ detection.
To address this, we designed a new detector to detect the spread of scintillation points. $0\nu\beta\beta$ decay produces a single scintillation point, while LLBG events create multiple points spread over a wider area. By detecting this spread, we can differentiate between $0\nu\beta\beta$ and LLBG events. The current KamLAND detector can't capture this spread, so the new detector will use advanced optical systems and sensors to do so. Simulations show that this approach can reduce LLBG by over 90%.
| Primary experiment | KamLAND-Zen |
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