A study of self-vetoing balloon vessel for liquid-scintillator detectors

KamLAND-Zen searches for neutrinoless double-beta decay with an ultra-pure liquid-scintillator (LS) filled with a custom-made clean nylon balloon. The primary backgrounds are radioactive impurities such as uranium and thorium series. To reduce them, we studied a self-vetoing balloon-shaped vessel fo...

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Bibliographic Details
Published in:Journal of physics. Conference series 2022-11, Vol.2374 (1), p.12111
Main Authors: Obara, S., Gando, Y., Ieki, S., Ikeda, H., Ishidoshiro, K., Nakamura, R.
Format: Article
Language:English
Subjects:
Balloons
Beta decay
Feasibility studies
Fluorescence
Physics
Polyethylene naphthalate
Pulse shape
Scintillation counters
Thorium
Uranium
Vessels
Waveforms
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Summary:KamLAND-Zen searches for neutrinoless double-beta decay with an ultra-pure liquid-scintillator (LS) filled with a custom-made clean nylon balloon. The primary backgrounds are radioactive impurities such as uranium and thorium series. To reduce them, we studied a self-vetoing balloon-shaped vessel for a future upgrade program, “KamLAND2-Zen”. We selected Polyethylene-Naphthalate (PEN) film which emit fluorescent light and performed the feasibility studies. Owing to its scintillation properties, 214 Bi background could be identified in the KamLAND2-Zen. Moreover, thanks to the different waveforms between the LS and the PEN, we can apply the pulse-shape-discrimination for 212 Bi-Po pileup background. We evaluated its background rejection efficiency as more than 90%. Resulting from these studies, it is possible to remove restrictions on fiducial volume in KamLAND2-Zen.
ISSN:1742-6588
1742-6596
DOI:10.1088/1742-6596/2374/1/012111