Optical Calibration Development for SNO+

在过去十年里出现的一些最令人兴奋的物理学是在中微子物理学领域。这里最前沿的实验之一是位于加拿大的萨德伯里中微子天文台(SNO)。英国在这一项目中发挥了主导作用，解决了“太阳中微子问题”，并首次清楚地证明了中微子以混合态的形式存在，这使得它们能够明显地从一种类型振荡到另一种类型。在这个极其成功的项目之后，一个后续的实验正在进行中，其物理目标非常多样化和有趣。SnO+将使用该仪器的改进版本来测量基本的太阳中微子过程(从而也调查中微子与物质耦合的细节)；搜索核子衰变的非标准模式；研究地球内部产生的中微子；寻找来自银河系超新星的中微子；以及搜索一种非常罕见的过程，称为“无中微子双β衰变”。对后者的观察既可以确定中微子的绝对质量，也可以确定中微子作为自己的反粒子，这可能会对我们对宇宙中物质/反物质不对称的理解产生影响。该项目预计将有一个快速的时间表，第一批数据将于2012年获得。要想揭示仪器观察到的相互作用的性质，需要详细了解光在探测器内是如何吸收、反射和散射的。英国做出的主要贡献之一涉及光纤网络，通过光纤网络，不同种类的光可以被引导到探测器，以帮助理解这些影响以及仪器如何响应它们。这笔赠款的工作是加强这一系统的能力，并为今后将有广泛应用的开发奠定基础。其中一个方面涉及开发一种激光系统，该系统能够通过其中一些纤维研究不同波长的光，以研究光散射。我们还将寻求开发一种方法来准确监控通过该系统的光的数量，这将使其对SNO+探测器内的其他测量有用。许多其他实验也需要类似的系统，甚至在粒子物理之外还有潜在的应用，例如那些涉及在偏远或危险环境中进行精确监测的实验。举个例子，一群核科学家提议使用一种类似但不那么复杂的系统，在后处理过程中实时监测冷却和冷凝水中的铀泄漏。要研究的另一个方面涉及对我们设计的一种新电路的进一步研究，该电路可以从LED产生极快的光脉冲。这种光还将被用来向下发送SNO+中的纤维，以确定探测元件在受光照射时的定时响应。然而，这样的设备也会有其他需要可靠、廉价、快速脉冲光源的应用。因此，与这种应用相关的研发不仅会对SNO+探索上述显著范围的科学问题的能力产生显著影响，而且还与其他潜在感兴趣的领域的关键问题有着天然的联系。

Some of the most exciting physics to emerge over the last decade has been in the field of neutrino physics. One of the forefront experiments here has been the Sudbury Neutrino Observatory (SNO), based in Canada. The UK has played a leading role in this project, solving the "Solar Neutrino Problem" and clearly demonstrating, for the first time, that neutrinos exists as mixed states which allow them to apparently "oscillate" from one type to another. On the heels of this tremendously successful project, a follow-on experiment is being pursued with a remarkably diverse and interesting range of physics objectives. SNO+ will use a modified version of the instrument to measure fundamental solar neutrino processes (thereby also investigating details of neutrino-matter couplings); search for non-standard modes of nucleon decay; study neutrinos generated from within the earth; look for neutrinos from galactic supernovae; and search for a very rare process called "neutrinoless double beta decay." An observation of the latter would both permit a determination of the absolute neutrino masses and would establish that neutrinos act as their own antiparticles, which could have consequences for our understanding of the matter/antimatter asymmetry in the universe. The project is anticipated to have a rapid timescale, with first data to be taken in 2012.The ability to unravel the nature of interactions observed by the instrument requires a detailed understanding of how light is absorbed, reflected and scattered inside the detector. One of the main contributions being made by the UK involves a network of optical fibres through which different kinds of light may be directed into the detector to help understand these effects and how instrument responds to them. The work of this grant is concerned with enhancing the capabilities of this system and laying the groundwork for future development that would have wide-ranging applications. One aspect of this involves developing a laser system capable of different wavelengths of light through some of these fibres to study light scattering. We will also look to develop a way to accurately monitor how much light gets sent through the system, which would make it useful for other measurements inside the SNO+ detector. Many other experiments also have the need for similar systems and there are even potential applications outside of particle physics, such as those involving precise monitoring in remote or hazardous environments. As one example, a group of nuclear scientists has proposed the use of a similar but much less sophisticated system to monitor real-time uranium leakage in cooling and condensation water during reprocessing. Another aspect to be studies involves further studies of a new circuit that we have designed to produce extremely fast light pulses from LEDs. This light will also be used to send down the fibres in SNO+ to determine the timing response of the detection elements when struck by light. However, such a device would also have other applications where a reliable, inexpensive, fast-pulsed light source is required.Therefore, the R&D associated with this application would not only have a noticeable impact on the ability of SNO+ to explore the remarkable range of scientific questions previously mentioned, but also has a natural link to critical problems in other areas of potential interest.