RUI: DRIFT-II: R&D and Operations for Dark Matter Detection

RUI: DRIFT-II: R

• 批准号: 0600840
• 负责人: Daniel Snowden-Ifft
• 金额: $ 52.61万
• 依托单位: Occidental College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0600840&HistoricalAwards=false
• 关键词: RUI; DRIFT; II; R& Operations

When these NSF researchers say they're on their way "back to the salt mine", they mean it. Professors Daniel P. Snowden-Ifft of Occidental College and Dinesh Loomba of the University of New Mexico are lead scientists on an international collaboration which works deep underground in a salt mine in England performing unique astrophysics measurements. Major funding for the work is provided by the National Science Foundation and the British Particle Physics and Astrophysics Research Council.The experiment, dubbed DRIFT (Directional Recoil Identification from Tracking) is a search for dark matter. Astrophysicists believe that the dark matter outweighs all the stars, gas and dust in our galaxy by nearly a factor of ten. It has been called dark matter since the Caltech astronomer Fritz Zwicky first measured its gravitational effects in the 1930's while finding it invisible in any telescope. Tremendous advances in telescopes and astronomical measurements since then have put the existence of dark matter on a firm footing but have not solved the mystery of what dark matter is. One of the few candidates for dark matter to have withstood the intense scrutiny over the last 75 years is the Weakly Interacting Massive Particle (WIMP).DRIFT uses a new type of particle detector (the "Negative Ion Time Projection Chamber" [NITPC]) invented in 1999 by the DRIFT team specifically to search for and positively identify WIMPs. WIMPs interact very rarely with matter. When they do they cause a nucleus to recoil much like two pool balls hitting each other. The DRIFT detector is capable of measuring the very short tracks of ionization left behind by low energy recoils traveling through the volume of gas. The detector is 1 cubic meter (about 35 cubic feet) in size and can measure tracks ~1 mm (1/25 inch) in length formed anywhere in its interior. It is a smart dark matter detector. The earth's motion through the halo of dark matter produces recoiling nuclei that "point" in a direction opposite our motion. DRIFT's ability to measure the direction of the recoils produced by dark matter therefore provides it with a unique signature of this dark matter. This allows DRIFT, unlike any other detector, to say with confidence that the recoils it detects are dark matter and not the more ubiquitous background neutrons. Also, by design, DRIFT is almost completely immune to the ever present backgrounds created by X-rays and gamma rays which plague other detectors. Reducing the background is also the reason DRIFT must be run deep underground in a salt mine, 1 kilometer (3300 feet) down, below the picturesque coastline of the North Yorkshire Moors. The Earth is bathed in a constant flux of high energy radiation from outer space (the "cosmic rays"). Without the shielding provided by 3300 ft of soil, salt, and rock, this radiation would wreak havoc with a detector as sensitive as DRIFT. There are several underground laboratories dedicated to particle astrophysics scattered around the world (South Dakota, Japan, Italy, Russia), and a major upgrade for a U.S. lab in the early planning stages. The NSF researchers on DRIFT had a long association with members of a British group who for more than a decade have operated an underground lab in the Boulby Mine. This is the deepest mine in Europe.The DRIFT team has installed and run two detectors DRIFT-I and DRIFT-II in the mine since 2002. Their work involves several graduate students as active participants in the research, both in data taking and analysis, and in development of new detectors for DRIFT.

当这些NSF研究人员说他们正在“回到盐矿”的路上时，他们的意思是。 西方学院的Daniel P. Snowden-Ifft教授和新墨西哥大学的Dinesh Loomba是一项国际合作的主要科学家，在英格兰一家盐矿中深入地在地下进行了独特的天体物理学测量。 国家科学基金会和英国粒子物理与天体物理学研究委员会提供了为这项工作提供的主要资金。该实验被称为漂移（跟踪的定向后坐力识别）是寻找暗物质的。 天体物理学家认为，暗物质在我们银河系中的所有恒星，气体和灰尘都远远超过十倍。 自加州理工学院天文学家Fritz Zwicky以来，它被称为暗物质，在1930年代首次测量了其引力效应，同时发现其在任何望远镜中都看不见。 从那时起，望远镜和天文测量的巨大进步使暗物质的存在在坚定的基础上，但没有解决什么是暗物质的奥秘。 在过去的75年中，少数对暗物质进行严格审查的候选者之一是弱相互作用的巨大粒子（wimp）。Drift使用一种新型的粒子探测器（“负离子时间投影室” [NITPC]），由漂移团队在1999年发明，专门搜索和正式识别Wimps。 wimps很少与物质相互作用。 当他们这样做时，它们会导致核向后退，就像两个泳池球互相击中。 漂移探测器能够测量通过流经气体体积的低能量后坐力留下的电离轨道的短轨道。检测器的尺寸为1立方米（约35立方英尺），可以测量轨道约1毫米（1/25英寸）的长度，其内部在其内部任何地方形成。这是一个智能的暗物质检测器。 地球穿过暗物质的运动会产生后退的核，该核“点”朝着我们的运动相反的方向“点”。 因此，Drift测量暗物质产生的后坐力方向的能力为其提供了这种暗物质的独特签名。 与任何其他检测器不同，这允许漂移充满信心地说，它检测到的后坐力是暗物质，而不是更加无处不在的背景中子。 同样，根据设计，漂移几乎完全不受X射线和伽玛射线创造的现有背景，这些背景会困扰其他探测器。 减少背景也是必须在盐矿中深处的地下，1公里（3300英尺）向下，在北约克郡摩尔人风景如画的海岸线下方。 地球以外太空的高能辐射的恒定通量（“宇宙射线”）沐浴。 如果没有3300英尺的土壤，盐和岩石提供的屏蔽，则这种辐射会造成严重的探测器，就像漂移一样敏感。 有几个专门针对世界各地粒子天体物理学的实验室（南达科他州，日本，意大利，俄罗斯），在早期计划阶段进行了美国实验室的主要升级。 NSF Drift的研究人员与英国团体的成员有很长的联系，他们在Boulby矿山经营了一个地下实验室。这是欧洲最深的矿山。自2002年以来，漂移团队已经在该矿山安装并运行了两个Drift-I和Drift-II。他们的工作涉及几名研究生作为研究和分析的研究参与者，以及开发新的Drifter。