低背景高富集130Te的TeO2单晶生长及中微子探测性能研究

The absolute mass of neutrino is very important for the most microcosmic particle physics. The new generation of neutrio absolute mass detector has a higher goal of detection capacity to the range of 0.01-0.001eV, and till now there is almost no detection material which can fulfill the requirement. Materials with low background and high enriched isotopes have the most possibility to increase signal to noise ratio (SNR)and detection ability. The aim of this proposal is the growth and properties study of low background TeO2 crystal with enriched 130Te more than 90%, through the study of melt-flow mechanism near the liquid-solid interface of seeding and Bridgman furnace design and optimization. The preparation will combine the purity control and the 130Te abundance control. Through the analysis of purity and 130Te abundance in different parts of a crystal, this proposal offers the opportunity to study the liquid-solid interface and the melt-flow mechanism in the unseen covered crucible during Bridgman growth process, which will provide a thoretical and experimental basis for the detection material of the new generation of neutrino absolute mass detector.

中微子绝对质量对最微观的粒子物理规律有重大意义。新一代中微子绝对质量探测器瞄准了0.01-0.001eV的高精度，而目前的探测材料均难以满足该精度要求。低背景高富集同位素材料是提高信噪比、增强探测能力的最有效途径。本项目拟通过研究接种生长界面处的熔体流动机理，设计优化下降生长炉，开展低背景高富集130Te（富集程度达90%以上）的氧化碲晶体生长及中微子探测性能研究。方法是将氧化碲晶体的纯度控制与130Te同位素的丰度控制相结合,通过分析晶体不同部位的纯度和130Te丰度分布情况，对下降法生长中难以直接观察的密闭坩埚内接种生长界面情况和熔体流动机理进行研究,为新一代中微子绝对质量探测器用材料提供理论和实验依据。

中微子绝对质量研究对揭示最微观的粒子物理规律有重大意义。本项目针对新一代中微子绝对质量探测器对探测材料高信噪比的新要求，从高纯原料制备出发，通过研究接种生长界面处的熔体流动机理，设计优化下降生长炉，开展了低背景高富集130Te的二氧化碲晶体生长及中微子探测性能研究。成功实现130Te金属粉体向高纯130TeO2粉体的化学转换，同位素富集程度仍然保持在92.2%。通过40%低富集TeO2晶体的生长，利用130Te同位素在不同晶体位置的变化规律，初步探讨了生长界面情况和熔体流动机理，为高富集晶体130TeO2晶体的下降炉设计提供了参考依据。研制出光学质量好、放射性纯度高的130TeO2晶体，具有非常优异的中微子探测性能，并首次探测到切伦科夫光，可有效去除α背景粒子信号高达98%以上。这一信噪比的极大提升，使130TeO2晶体成为新一代中微子探测实验最具竞争力的候选材料。