HALO ? the helium and lead observatory for supernova neutrinos
HALO ? the helium and lead observatory for supernova neutrinos
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DOI：
10.1088/1742-6596/136/4/042077
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发表时间：
2008
影响因子：
1.4
通讯作者：
S. Yen
中科院分区：
文献类型：
--
作者：
C. Duba;F. Duncan;J. Farine;A. Habig;A. Hime;R. Robertson;K. Scholberg;T. Shantz;C. Virtue;J. Wilkerson;S. Yen
氦铅观测站（英语：Helium and Lead Observatory，HALO）是一个超新星中微子探测器，正在为SNOLAB的建设而开发。它的目的是实现一个利基作为一个长期，低成本，高寿命，低维护，专用超新星探测器。它将由80吨铅建造，来自深河宇宙射线站的退役，并配备了来自SNO实验最后阶段的大约384米的3 He中子探测器。铅中的带电中微子和中性流中微子相互作用从铅核中排出中子，使探测到的中子爆发成为超新星探测的标志。现有的中微子探测器大多是水切伦科夫和液体闪烁体类型，它们主要通过这些材料中氢核上的带电电流相互作用对电子反中微子敏感。相比之下，像铅这样的重核的大量中子过剩会导致电子反中微子引起的保利-阻塞pn跃迁，使HALO主要对电子中微子敏感。虽然任何超新星中微子数据都将为超新星动力学提供一个宝贵的窗口，但电子中微子CC通道通过味道交换和光谱分裂对粒子物理学具有有趣的敏感性，这是由于超新星核心中的MSW集体中微子-中微子相互作用，宇宙中唯一有足够密度的中微子发生的地方。这样的数据可以提供一个测试θ13 <$0和一个倒置的中微子质量等级。此外，1个中子与2个中子事件的比率将是冷却中子星星温度的量度。对于80吨重的探测器，一颗10千秒差距的超新星在没有集体ν-ν相互作用的情况下估计会产生43个被探测到的中子，而在有集体ν-ν相互作用的情况下会产生更多的中子。铅的高中微子横截面和低中子吸收横截面，沿着铅的适度成本，使得该技术可扩展，并且正在积极考虑未来升级到1千吨量级。
The Helium and Lead Observatory (HALO) is a supernova neutrino detector under development for construction at SNOLAB. It is intended to fulfill a niche as a long term, low cost, high livetime, and low maintenance, dedicated supernova detector. It will be constructed from 80 tonnes of lead, from the decommissioning of the Deep River Cosmic Ray Station, and instrumented with approximately 384 meters of 3He neutron detectors from the final phase of the SNO experiment. Charged- and Neutral-Current neutrino interactions in lead expel neutrons from the lead nuclei making a burst of detected neutrons the signature for the detection of a supernova. Existing neutrino detectors are mostly of the water Cerenkov and liquid scintillator types, which are primarily sensitive to electron anti-neutrinos via charged-current interactions on the hydrogen nuclei in these materials. By contrast, the large neutron excess of a heavy nucleus like Pb acts to Pauli-block pn transitions induced by electron anti-neutrinos, making HALO primarily sensitive to electron neutrinos. While any supernova neutrino data would provide an invaluable window into supernova dynamics, the electron neutrino CC channel has interesting sensitivity to particle physics through flavour-swapping and spectral splitting due to MSW-like collective neutrino-neutrino interactions in the core of the supernova, the only place in the universe where there is a sufficient density of neutrinos for this to occur. Such data could provide a test for θ13 ≠ 0 and an inverted neutrino mass hierarchy. In addition, the ratio of 1-neutron to 2-neutron events would be a measure of the temperature of the cooling neutron star. For the 80 tonne detector, a supernova at 10 kpc is estimated to produce 43 detected neutrons in the absence of collective ν-ν interactions, and many more in their presence. The high neutrino cross-section and low neutron absorption cross-section of lead, along with the modest cost of lead, makes this technology scalable and a future upgrade, to of order 1 kilotonne, is under active consideration.