1 chung-yao chao fellowship interview 5 月 22 日, 2015 loh chang wei
TRANSCRIPT
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Chung-Yao Chao Fellowship Interview
5 月 22 日, 2015
Loh Chang Wei
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个人简介
Loh, Chang Wei ( 罗章维 )
马来西亚 籍
2015 年 3 月 加入 南京大学 祁鸣 教授 科研组
Thomson Reuters ResearcherID # I-1310-2014 http://www.researcherid.com/rid/I-1310-2014
南京大学 的 科研路线:
Diamond detector (ATLAS upgrade and beyond)
Daya Bay experiment data analysis
Education
Ph.D. from the University of British Columbia, Canada加拿大 英属哥伦比亚 大学, 2014UBC Four-Year Fellowship, 2009Graduate Entrance Scholarship, 2006
B.Sc. from the University of Malaya, Malaysia马来西亚 马来亚 大学, 2006
Student exchange program ( 学生交流 ), Singapore新加坡国立 大学 (NUS), 2004ASEAN University Network AUN-NUS Study Award, 2004
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Experience (Non-Research)
知识产权:专利代理人 (马来西亚), 2013 – 2015
助教 (加拿大), 2006 – 2013
暑假工作 (美国), 2006
作者 ( 兼职 ) [Pearson ; 培生教育集团 ] (马来西亚), 2005-2006
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Previous Research in Canada
for ATLAS, LHC at CERN
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Previous Research in Canada(ATLAS, LHC at CERN)
Search for Long-Lived Particles Decay with Displaced Vertices
Difficult search in hadron colliders like ATLAS
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We are proud to say that ATLAS is the first to publish on such decays in experimental particle physics.
Publication (1)
Title: Search for long-lived, heavy particles in final states with a muon and multi-track displaced vertex in proton-proton collisions at root s=7 TeV with the ATLAS detector
Author(s): The ATLAS CollaborationSource: Physics Letters B Volume: 719 Issue: 4-5 Pages: 280-298 Published: 2013 Times Cited: 20
Invented new techniques :
1. Pure fake vertex estimation technique
2. Fake track + material vertex estimation technique
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Brief on one :
Pure fake vertex estimation technique
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Publication ( 2 )
Title: Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS
Author(s): The ATLAS Collaboration Source: Physics Letters B Volume: 707 Issue: 5 Pages: 478-496 Published: 2012 Times Cited: 27
Invented new background estimation technique :
1.
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Data-driven background and distribution estimation:
Reweighting according to mass and number of tracks in the control region from two sets of differently-triggered events
Publication ( 3 )
Title: Search for Supersymmetry in Events with Three Leptons and Missing Transverse Momentum in root s=7 TeV pp Collisions with the ATLAS Detector
Author(s): The ATLAS Collaboration Source: Physical Review Letters Volume: 108 Issue: 26 Published: 2012 Times Cited: 26
Contribution to another ATLAS physics group with my displaced vertex expertise :
a. Decay-in-flight muon background study from long-lived hadron decays
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Other works
Unfinished idea from my time in Canada but documented in my thesis:CERN-THESIS-2013-33
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Difficult search !Invented new signal-background discriminators and proved that it is not difficult.
Research at Nanjing University
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Research at Nanjing U. (ATLAS upgrade)
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Main tech. candidates for MiniFCal :
1. Liquid argon2. Diamond (upgrade and for the future)
Super Large Hadron Collider (sLHC)> 5 X 1034 cm2 s-1
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Benefits of Diamond
High thermal conductivity (No need for cryostats unlike liquid argon)
High radiation hardness
Low noise
Good charge collection distance
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Degradation curve
Kurchanikov & Cheplakov, 2013
Polycrystalline diamond
Neutrons 1 MeV (Dubna, Russia)
(Canada)
Polycrystalline diamond degrades faster under neutron irradiation
Single crystal diamond (scCVD) sample0.6 X 0.6 cm2 size, 300 – 400 microns thick
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Why not substitute polycrystalline with single crystal diamond?
scCVD 2 – 3 times better charge collection distance than polycrystalline diamond.Isberg, et al., 2004, 14th European Conf. on Diamond, Diamond-Like Mat., C. Nanotube, Nitrides and Si. Carbide
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Plan for Diamond (Looking Forward)
Monte Carlo (Geant4) simulation within ATLAS
Electrical characterization, e.g.
Irradiation with hadrons (proton, neutron, pion)
Metallization
• Prelim.: Square wafers (1 cm X 1 cm), O(1) mm separation in η and ϕ;• Test various geometries;• Irradiation simulation based on experimental results on single wafer;• Possible front-end electronics and readouts for online-offline mapping,
pulse-shaping.
• Charge collection distance, d;• d ~ collected charge;• d depends on radiation damage history of sample.
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Plan B (If things are not as expected)
Still publishable and with patents, if any, e.g.
( 权利要求 )
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Research at Nanjing U.(for the Daya Bay experiment)
Cosmic muons interacting with liquid scintillator can produce 9Li and 8He background mimicking antineutrino signal.
vs.
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Daya Bay Antineutrino Experiment Work
Reconstruct muon track with a charge-weighted coordinate computation:
Lingyu Wang, DYB-doc # 7838-v9
21Distributions are almost similar for all “symmetric” K-weights.Charge-weighted method (CWM) for track coordinates can be improved.
Deviation of reco. from truth muon track coord.
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Summary
Self-introduction
Previous work in ATLAS until the shutdown thereof after Higgs discovery
Future work with ATLAS upgrade and beyond, and with Daya Bay experiment data analysis
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多谢
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BACKUP
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Charge collection distance = mean distance that electrons and holes drift apart before Being trapped
26YuenKeung, Hor (2009)
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Invented new techniques :
2 。 Fake track + material vertex estimation technique
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K-short hadron mass peak