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

中微子质量的基本问题在宇宙学、宇宙演化的研究和基本粒子理论的完成中是重要的。中微子是宇宙中最多产的粒子，直到1998年人们才确定它们有质量。现在实验已经很好地证实，在从太阳到地球的过程中，那些在我们的高层大气中产生的物质确实会从一种类型转变为另一种类型，这就要求它们确实有质量。确定它们的质量也可能决定它们是否可以解释部分暗物质（有时被称为宇宙缺失的质量）。这些实验被称为中微子振荡实验；但是，不能告诉我们它们有多少质量，只能说它们的质量不为零。有两种方法可以直接测定中微子的质量。在第一种方法中，对轻核放射性衰变产生的β粒子的能谱进行了精确测量。高能端附近的能谱偏离标准理论形状是电子型中微子质量的量度。这些实验非常困难，在质量敏感性方面也有一定的限制。然而，在它们的敏感范围内，它们是非常有价值的。在中微子本身就是反粒子的情况下，有一种奇异的放射性衰变称为无中微子双β衰变，它对中微子的质量要敏感得多。此外，通过直接观察确定这一过程的存在，将证明中微子本身就是反粒子。这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。在早期的宇宙中，如果没有一些粒子多于反粒子，我们自己，以及我们所看到的一切，就不可能存在。CUORE和Majorana项目都是大型的下一代中微子双β衰变实验。它们的设计目的是探测一个质量范围，比目前三个实验的灵敏度高10倍，其中两个实验是由该基金的PI以领导角色参与的。马约拉纳实验是一个500公斤的高纯度锗探测器阵列，同位素富集于76Ge，候选母核双β衰变核。它涉及5个国家实验室和8所大学。它将在美国用美国技术建造。I涉及许多研究生，将成为博士论文材料的丰富来源。在核武器不扩散和国土防御方面有一些有用的附带技术。CUORE是一种750千克的低温氧化碲探测器阵列，用于寻找同位素130Te的中微子双β衰变。这是意大利和美国的合作项目，目前正在意大利阿塞吉的格兰萨索国家实验室建造。这是一项新技术，因为它的体积很大。它提供了与马约拉纳大学相同的教育机会，并且正在培训美国研究生和博士后科学家使用美国不存在的大型低温探测器技术。

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.