Next Generation Double-Beta Experimints:CUORE/CUORICINO and Majorana

下一代双 Beta 实验：CUORE/CUORICINO 和 Majorana

• 批准号: 0500337
• 负责人: Frank Avignone
• 金额: $ 96万
• 依托单位: University South Carolina Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-15 至 2009-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0500337&HistoricalAwards=false
• 关键词: Next; Generation; Double; Beta; Experimints

The fundamental question of neutrino mass is important in cosmology, the study of the evolution of the universe, and for the completion of a theory of elementary particles. Neutrinos are the most prolific particles in the universe, and only since 1998 has it been established that they have any mass at all. It has now been well established experimentally, that in traversing from the sun to earth, and those created in our upper atmosphere, do change from one type to another, which requires that they do have mass. Determining their mass may also determine if they could account for part of the dark matter (sometimes called the missing mass of the universe). These experiments called neutrino oscillation experiments; however, cannot tell us how much mass they possess, just that their masses are not zero. There are two methods to directly determine the masses of neutrinos. In the first method, a precision measurement is made of the energy spectra of beta particles from radioactive decay of light nuclei. The deviation from the canonical theoretical shape of the energy spectrum near the high-energy end is a measure of the mass of the electron-type neutrino. These experiments are very difficult and are somewhat limited in mass sensitivity. Nevertheless, within their range of sensitivity, they are very valuable.In the case that neutrinos are their own anti-particles, there is an exotic radioactive decay called neutrinoless double-beta decay, that would be far more sensitive to neutrino mass. In addition, establishing by direct observation that this process exists, would prove that neutrinos are their own anti-particles. This in itself is extremely important for completing the theory of elementary particles. It would also support specific models of the very early universe that explain why the universe is almost completely particles at present, with almost no anti-particles. Without some small excess of particles over anti-particles in the very early universe, we ourselves, and all we see, could not exist today. The projects CUORE and Majorana are both large, next generation neutrinoless double beta decay experiments. They are being designed to probe a mass range a factor of ten more sensitive than presently exists from three experiments, two of which the PI of this grant participated in with leadership roles. The Majorana experiment is a proposed 500 kg array of high purity Ge detectors, isotopically enriched in 76Ge, the candidate parent double beta decay nucleus. It involves five national laboratories and eight universities. It would be built in the US with US technology. I involves many graduate students and will be a prolific source of PhD thesis material. There are a number of spin-off technologies useful in nuclear weapon non-proliferation and in homeland defense.CUORE is a proposed 750 kg array of cryogenic detectors of tellurium oxide to search for the neutrinoless double-beta decay of the isotope 130Te. It is a collaboration between Italy and the US, and is being constructed in the Gran Sasso National Laboratory in Assergi, Italy. It is a new technology because of its mass. It offers the same kind of educational opportunities as does Majorana, and is training US graduate students and post doctoral scientists in the technology of very large cryogenic detectors that do not exist in the US.

中微子质量的基本问题在宇宙学、宇宙演化的研究以及基本粒子理论的完善中都很重要。中微子是宇宙中最多产的粒子，直到1998年才确定它们有质量。现在已经通过实验很好地证实，在从太阳到地球的过程中，以及在我们的高层大气中产生的那些，确实会从一种类型变成另一种类型，这就要求它们确实有质量。确定它们的质量也可以确定它们是否可以解释部分暗物质（有时称为宇宙的缺失质量）。这些实验被称为中微子振荡实验;然而，不能告诉我们它们拥有多少质量，只是它们的质量不为零。有两种方法可以直接确定中微子的质量。第一种方法是对轻核放射性衰变产生的β粒子能谱进行精确测量。高能端附近能谱与正则理论形状的偏差是电子型中微子质量的度量。这些实验非常困难，并且在质量灵敏度方面有些限制。然而，在它们的灵敏度范围内，它们是非常有价值的。在中微子是自己的反粒子的情况下，有一种奇异的放射性衰变称为无中微子双β衰变，它对中微子质量的灵敏度要高得多。此外，通过直接观察确定这个过程的存在，将证明中微子是它们自己的反粒子。这一点本身对于完成基本粒子理论是极其重要的。它还将支持非常早期宇宙的特定模型，解释为什么宇宙目前几乎完全是粒子，几乎没有反粒子。如果在早期宇宙中没有比反粒子多出一些的粒子，我们自己和我们所看到的一切就不可能存在于今天。CUORE和Majorana项目都是大型的下一代无中微子双β衰变实验。他们被设计来探测一个质量范围，这个范围比目前存在的三个实验灵敏十倍，其中两个实验是由本基金的PI领导的。马约拉纳实验（英语：Majorana experiment）是一个建议的500公斤高纯度锗探测器阵列，富含同位素76锗，候选的母双β衰变核。它涉及五个国家实验室和八所大学。它将在美国使用美国技术建造。我涉及许多研究生，并将成为博士论文材料的丰富来源。CUORE是一个750公斤重的氧化碲低温探测器阵列，用于探测同位素130 Te的无中微子双β衰变。它是意大利和美国的合作项目，目前正在意大利阿塞尔吉的格兰萨索国家实验室建造。这是一项新技术，因为它的质量。它提供了与马约拉纳大学相同的教育机会，并正在培训美国研究生和博士后科学家掌握美国不存在的超大型低温探测器技术。