Fabrication of Liquid Scintillators Loaded with 6-Phenylhexanoic Acid-Modified ZrO2 Nanoparticles for Observation of Neutrinoless Double Beta Decay

• Published in: Nanomaterials (Basel, Switzerland) Vol. 11; no. 5; p. 1124
• Main Authors: Watanabe, Akito, Magi, Arisa, Yoko, Akira, Seong, Gimyeong, Tomai, Takaaki, Adschiri, Tadafumi, Hayashi, Yamato, Koshimizu, Masanori, Fujimoto, Yutaka, Asai, Keisuke
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 27.04.2021; MDPI
• Subjects: 6-phenylhexanoic acid; Acids; Beta decay; Beta rays; Decay; Fabrication; Hydrocarbons; hydrothermal synthesis; liquid scintillator; Metal oxides; Nanoparticles; neutrinoless double beta decay; Organic liquids; Particle decay; Particle physics; Radiation; Scintillation; Scintillation counters; Sensors; Solvents; Spectroscopy; Spectrum analysis; Synthesis; Toluene; Zirconium dioxide; Zirconium isotopes; ZrO2; Japan
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano11051124

The observation of neutrinoless double beta decay is an important issue in nuclear and particle physics. The development of organic liquid scintillators with high transparency and a high concentration of the target isotope would be very useful for neutrinoless double beta decay experiments. Therefore, we propose a liquid scintillator loaded with metal oxide nanoparticles containing the target isotope. In this work, 6-phenylhexanoic acid-modified ZrO2 nanoparticles, which contain 96Zr as the target isotope, were synthesized under sub/supercritical hydrothermal conditions. The effects of the synthesis temperature on the formation and surface modification of the nanoparticles were investigated. Performing the synthesis at 250 and 300 °C resulted in the formation of nanoparticles with smaller particle sizes and higher surface modification densities than those prepared at 350 and 400 °C. The highest modification density (3.1 ± 0.2 molecules/nm2) and Zr concentration of (0.33 ± 0.04 wt.%) were obtained at 300 °C. The surface-modified ZrO2 nanoparticles were dispersed in a toluene-based liquid scintillator. The liquid scintillator was transparent to the scintillation wavelength, and a clear scintillation peak was confirmed by X-ray-induced radioluminescence spectroscopy. In conclusion, 6-phenylhexanoic acid-modified ZrO2 nanoparticles synthesized at 300 °C are suitable for loading in liquid scintillators.