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INPAC-Seminar 83: ICF中子测量技术 |
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作者：Saturnman
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周二, 2012年 01月 10日 15:14 |
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INPAC-Seminar 83 Title: ICF中子测量技术 Speaker: 金革 教授 (中国科学技术大学) Time and place: 15:00, January 13 (Friday), 2012, Lecture Hall/INPAC (上海交通大学粒子物理宇宙学研究所，包玉刚图书馆东楼四楼(从北门进)) Abstract 高温高密度热核点火是ICF研究的核心问题。根据劳森判据，在聚变过程中，燃料面密度<ρR>≥0.4g/cm2时才有可能实现热核点火。考虑到制备氚靶昂贵的价格和安全性，进行的内爆实验，都是以充纯氘燃料为主，其次级中子产额只有105—106。通过测量充纯氘燃料靶丸的次级中子能谱，可以给出高压缩状态下的<ρR>,同时还可以分析影响ICF内爆的各种物理过程，达到了解各种内爆中靶丸的压缩程度、燃料的燃烧情况和优化各种靶及黑腔的设计的目的。为了在这样低的中子产额条件下获得离子温度Ti和〈ρR〉，利用大面积中子探测器阵列测量中子的飞行时间谱目前几乎是国际上使用的唯一探测手段，已成为诊断Ti和<ρR>的标准技术。美国、日本和英国都在进行这种技术的研究，并建造了几套探测器阵列系统。 在神光-III激光装置上进行的ICF实验对大面积中子探测器阵列的探测指标要求为：其次级DT中子探测水平达到4 ´ 105，中子飞行时间谱时间分辨对应的中子能量分辨（FWHM）达到90keV。根据这些要求，结合神光-III装置实验现场的条件，并参考国外ICF实验装置中大面积中子探测器阵列的设计的性能指标，可以计算出神光-III上大面积中子探测器阵列的规模为：960个通道、飞行距离16.67米、DT中子探测效率约为20%；中子飞行时间谱总的时间分辨要求达到1.0ns，其中，对电子学系统总体时间分辨更是要求达到100ps。 |
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最后更新 ( 周三, 2012年 01月 11日 14:09 )
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INPAC-Seminar 82: Dark Matter at Colliders |
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作者：Saturnman
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周四, 2012年 01月 05日 06:52 |
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INPAC-Seminar 82 Title: Dark Matter at Colliders Speaker: Dr. Yang Bai (白杨) (SLAC National Accelerator Laboratory, CA, USA) Time and place: 10:30, January 9 (Monday), 2012, Lecture Hall/INPAC (上海交通大学粒子物理宇宙学研究所，包玉刚图书馆东楼四楼(从北门进)) Abstract Although the fact that a large fraction of the matter in the universe is non-baryonic is beyond doubt, the exact composition of the dark matter is still shrouded in mystery. Using ultra-sensitive detectors in the deep underground laboratories, physicists are attempting to directly detect dark matter particles streaming from space. At colliders, physicists hope to manufacture large numbers of dark matter particles and study their properties. I will first use an effective field theory approach to demonstrate the power of colliders by comparing these two approaches. I will then describe the recent efforts on searching for dark matter particles at colliders and how imminent discoveries may change our fundamental understanding of physics and the universe. |
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最后更新 ( 周四, 2012年 01月 05日 06:57 )
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INPAC-Seminar 80: Fermilab Muon g-2 Experime |
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作者：Saturnman
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周三, 2011年 12月 14日 09:35 |
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INPAC-Seminar 80 Title: Fermilab Muon g-2 Experiment and its Detector Design Speaker: Prof. Tianchi Zhao (University of Washington, Seattle, USA) Time and place: 12:30, December 16 (Friday), 2011, Lecture Hall/INPAC (上海交通大学粒子物理宇宙学研究所，包玉刚图书馆东楼四楼(从北门进)) Abstract The Fermilab muon g-2 experiment plans to use the existing BNL E821 muon strorage ring and constructs a new detector system to measure the anomalous magnetic moment of the muons to a precision of 0.14ppm, a fourfold improvement over the previous Brookhaven E821 experiment. The muon anomaly is a fundamental physics quantity, which can be precisely measured and accurately computed within the Standard Model and a comparison of experiment to theory is a sensitive test of the completeness of the theory. The current comparison to the accepted theory shows a deviation of more than 3 standard deviations, which might be an indication of New Physics beyond the Standard Model. |
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INPAC-Seminar 81: Symmetry energy from syste |
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作者：Saturnman
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周一, 2011年 12月 26日 01:35 |
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INPAC-Seminar 81 Title: Symmetry energy from systematic of isobaric analog states Speaker: Prof. Pawel Danielewicz (Michigan State University, East Lansing, USA) Time and place: 13:00, December 28 (Wednesday), 2011, Lecture Hall/INPAC (上海交通大学粒子物理宇宙学研究所，包玉刚图书馆东楼四楼(从北门进)) Abstract Symmetry energy describes how the net nuclear energy changes with changing inequality between neutron and proton numbers. Knowledge of the symmetry energy, and especially its dependence on density in uniform medium, is needed for extrapolating from nuclei to matter in neutron stars. Charge invariance of nuclear interactions can be used to demonstrate that nuclei can be assigned nuclear symmetry coefficients that depend on mass and reflect changes of symmetry energy with density, within nuclear surface. Those coefficients are extracted nucleus-by-nucleus from excitation energies to isobaric analog states. The variation of those coefficients with mass is then used to constrain the density dependence of symmetry energy in uniform matter. As nuclear ground states minimize energy, neutrons and protons displace relative to each other to minimize symmetry energy contribution to the net energy. Universality of the features of neutron and proton distributions in nuclei, in the context of symmetry energy, is discussed. |
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最后更新 ( 周一, 2011年 12月 26日 01:38 )
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INPAC-Seminar 79: Dark matter and ne |
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作者：Saturnman
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周一, 2011年 12月 05日 03:10 |
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INPAC-Seminar 79 Title: Dark matter and neutrinoless double beta decay searches with high purity Ge detectors Speaker: Prof. J. F. Wilkerson (University of North Carolina and Oak Ridge National Laboratory) Time and place: 12:30, December 9 (Friday ), 2011, Lecture Hall/INPAC (上海交通大学粒子物理宇宙学研究所，包玉刚图书馆东楼四楼(从北门进)) Abstract The MAJORANA collaboration is constructing the DEMONSTRATOR, an ultra-low background array consisting of 40 kg of germanium detectors, at least half of which will be enriched to 86% in 76Ge. The primary goal is to show the feasibility for a tonne scale search for neutrinoless double-beta decay. With its low energy threshold, the array will also be able to search for light WIMP dark matter. The DEMONSTRATOR will utilize p-type point contact detectors which offer attractive features including low-energy (sub keV) thresholds and superior pulse shape discrimination of multisite events. Recent measurements from CoGeNT and MALBEK, a prototype detector for MAJORANA, will be discussed. |
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最后更新 ( 周一, 2011年 12月 05日 08:43 )
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