Chung-Yao Chao Fellowship Interview Loh Chang Wei 5

Chung-Yao Chao Fellowship Interview Loh Chang Wei 5 月 22 日， 2015 1

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 Researcher. ID # I-1310 -2014 http: //www. researcherid. com/rid/I-1310 -2014 南京大学 的 科研路线 ： n Diamond detector (ATLAS upgrade and beyond) n Daya Bay experiment data analysis 2

Education n Ph. D. from the University of British Columbia, Canada 加拿大 英属哥伦比亚 大学， 2014 UBC Four-Year Fellowship, 2009 Graduate Entrance Scholarship, 2006 n B. Sc. from the University of Malaya, Malaysia 马来西亚 马来亚 大学，2006 n Student exchange program (学生交流), Singapore 新加坡国立 大学 (NUS), 2004 ASEAN University Network AUN-NUS Study Award, 2004 3

Experience (Non-Research) n 知识产权：专利代理人 （马来西亚），2013 – 2015 n 助教 （加拿大），2006 – 2013 n 暑假 作 （美国），2006 n 作者 (兼职) [Pearson； 培生教育集团] （马来西亚）， 2005 -2006 4

Previous Research in Canada for ATLAS, LHC at CERN 5

Previous Research in Canada (ATLAS, LHC at CERN) Search for Long-Lived Particles Decay with Displaced Vertices Difficult search in hadron colliders like ATLAS n We are proud to say that ATLAS is the first to publish on such decays in experimental particle physics. 6

Publication (1) n 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 Te. V with the ATLAS detector Author(s): The ATLAS Collaboration Source: Physics Letters B Volume: 719 Issue: 4 -5 Pages: 280298 Published: 2013 Times Cited: 20 Invented new techniques： 1. 2. Pure fake vertex estimation technique Fake track + material vertex estimation technique 7

n Brief on one： Pure fake vertex estimation technique 8

Publication（2） Title: Search for displaced vertices arising from decays of new heavy particles in 7 Te. V pp collisions at ATLAS n 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. 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 9

Publication（3） n Title: Search for Supersymmetry in Events with Three Leptons and Missing Transverse Momentum in root s=7 Te. V 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 10

Other works n Unfinished idea from my time in Canada but documented in my thesis: CERN-THESIS-2013 -33 Difficult search ! Invented new signal-background discriminators and proved that it is not difficult. 11

Research at Nanjing University 12

Research at Nanjing U. (ATLAS upgrade) Super Large Hadron Collider (s. LHC) > 5 X 1034 cm 2 s-1 Main tech. candidates for Mini. FCal : 1. Liquid argon 2. Diamond (upgrade and for the future) 13

Benefits of Diamond n High thermal conductivity (No need for cryostats unlike liquid argon) n High radiation hardness n Low noise n Good charge collection distance 14

Degradation curve Polycrystalline diamond (Canada) Neutrons 1 Me. V (Dubna, Russia) Polycrystalline diamond degrades faster under neutron irradiation Kurchanikov & Cheplakov, 2013 15

Why not substitute polycrystalline with single crystal diamond? Single crystal diamond (sc. CVD) sample 0. 6 X 0. 6 cm 2 size, 300 – 400 microns thick sc. CVD 2 – 3 times better charge collection distance than polycrystalline diamond. Isberg, et al. , 2004, 14 th European Conf. on Diamond, Diamond-Like Mat. , C. Nanotube, Nitrides and Si. Carbide 16

Plan for Diamond (Looking Forward) n Monte Carlo (Geant 4) simulation within ATLAS • • n 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. Electrical characterization, e. g. • Charge collection distance, d; • d ~ collected charge; • d depends on radiation damage history of sample. n Irradiation with hadrons (proton, neutron, pion) n Metallization 17

Plan B (If things are not as expected) n Still publishable and with patents, if any, e. g. (权利要求) 18

Research at Nanjing U. (for the Daya Bay experiment) n Cosmic muons interacting with liquid scintillator can produce 9 Li and 8 He background mimicking antineutrino signal. vs. 19

Daya Bay Antineutrino Experiment Work n Reconstruct muon track with a charge-weighted coordinate computation: Lingyu Wang, DYB -doc # 7838 -v 9 20

Deviation of reco. from truth muon track coord. Distributions are almost similar for all “symmetric” K-weights. Charge-weighted method (CWM) for track coordinates can be improved. 21

Summary n Self-introduction n Previous work in ATLAS until the shutdown thereof after Higgs discovery n Future work with ATLAS upgrade and beyond, and with Daya Bay experiment data analysis 22

多谢 23

BACKUP 24

Charge collection distance = mean distance that electrons and holes drift apart before Being trapped 25

Yuen. Keung, Hor (2009) 26

27

n Invented new techniques： 2。Fake track + material vertex estimation technique K-short hadron mass peak 28