Chung-Yao Chao Fellowship Interview. Marco Grassi

Transcription

1 Chung-Yao Chao Fellowship Interview Marco Grassi

2 Résumé Coming from an High Energy Physics Background (CMS at LHC) PhD at Sapienza Univ (Rome) & CERN Measurement of the Standard Model Higgs Boson Couplings by Means of an Exclusive Analysis of its Diphoton Decay Channel Moved to Neutrino Physics 2013-now Postdoctoral Fellow at IHEP, CAS Working on Daya Bay Experiment and JUNO Experiment (supervisor Prof. Cao Jun) Last two years have been quite intense Jun 14 Poster at Neutrino 14, Boston (USA) Sep 14 Published Grassi et al, JHEP 1409 (2014), 49 Oct 14 Contribution to JUNO Physics Book Oct 14 Workshop at Charles University, Prague, (Czech Republic) Feb 15 Seminar + Workshop at Ferrara University, Ferrara (Italy) Mar 15 Submitted arxiv May 15 Seminar at Institute of Modern Physics CAS, Lanzhou (PR China) May 15 Talk at IHEP-INFN annual cooperative meeting, Beijing (PR China) Upcoming Poster at Lepton Photon 15, Ljubljana (Slovenia) 2

3 JUNO Cosmogenic Backgrounds (1) Juno Doc #281 Cosmic muons interacting with Liquid Scintillator (LS) produce 9 Li and 8 He isotopes Isotope decays mimic signal signature (Inverse Beta Decay reaction) Goal: Quantify the yield of such isotopes through simulations Events / GeV / s -1-2 All Muons 1 Muon 2 Muons Muons 3 Muons Muon Energy [GeV] 3 3

4 JUNO Cosmogenic Backgrounds (2) Goal: Determine a veto strategy to reject cosmogenic backgrounds Juno Doc #458 If muon track is reconstructed, veto a 3.5 m wide cylinder surrounding it If muon is showering (high energy deposited) veto the whole detector Events / Bin / s Muon Events Total Event Rate 5.4 Hz Total Deposited Energy E TOT E TOT MeV cm (track length) 0.1 Li Yield / Bin / s 9 ( 0 ) Lithium Yield 9-3 Total Li Yield 1.67 Hz Energy [GeV] 4

5 Paper on Cosmogenic Backgrounds Doi:.07/JHEP09(2014)049 ArXiv eprint:

6 JUNO Yellow Book Solar Neutrino Detection with JUNO Solar neutrino fluxes measured so far (Borexino) confirmed the Standard Solar Model However current data does not allow to distinguish between different versions of the model: low Z vs high Z Sun composition Juno might further constrain the 8 B and 7 Be neutrino fluxes, hence allowing the solution of this puzzle Signal rate (4.5 events/day/kt) and neutrino energy are really low. Study of backgrounds plays a key role in determining LS required radiopurity 6

7 JUNO Top Tracker In collaboration with IPHC, Strasbourg, France Juno Doc #562 7

8 Seasonal Muon Flux Modulation (1) Strong theoretical interest in correlating underground muon flux with temperature data in the high atmosphere DayaBay offers 3 underground experimental halls and 8 identical detectors: ideal environment to control systematics Daya Bay AD 1: 0.3% modulation with period = days Jan 12 Apr 12 Jul 12 Oct 12 Dec 12 Apr 13 Jul 13 Oct 13 Ling Ao AD 1: 0.39% modulation with period = days DYB Doc #9957 Jan 12 Apr 12 Jul 12 Oct 12 Dec 12 Apr 13 Jul 13 Oct Far Hall AD 1: 0.57% modulation with period = 357 days Jan 12 Apr 12 Jul 12 Oct 12 Dec 12 Apr 13 Jul 13 Oct Far Hall AD 3: 0.53% modulation with period = days Jan 12 Apr 12 Jul 12 Oct 12 Dec 12 Apr 13 Jul 13 Oct

9 Seasonal Muon Flux Modulation (2) DayaBay muon data spans more than 2 years Muon dataset and temperature dataset get binned with daily resolution Data points are divided by experimental hall and by detector Each correlation plot gets fitted with a linear function to compute correlation coefficient Rate [%] 2 1 EH3 AD2 Pre Sum '12 χ 2 = 181 / 208 ndf Rate [%] 2 1 EH3 AD2 Post Sum '12 χ 2 = 407 / 379 ndf Fit func: y = mx+q Fit func: y = mx+q -2 m = 0.68 ± 0.04 q = 0. ± m = 0.54 ± 0.03 q = ± Temperature [%] Temperature [%] 9

10 What s Next

11 JUNO Electronics Juno is expected to have O(20000) PMTs Each PMT needs a flash-adc to sample the output signal The design of the readout electronics is non-trivial: number of channels & size of the detector are similar to a HEP experiment Electronics simulation is fundamental to properly design front-end boards Developing a novel approach to simulate efficiently the Juno electronics and give important input to hardware people 11

12 PMT Charge Reconstruction PMT Single Photo-electron Simple Output Waveform Many Photo-electrons Complex Waveform Non-trivial Charge Extraction ADC Counts Raw Waveform True Photo-electrons Exploit JUNO readout based on FADC Fourier Unfolding of Template Signal Noise Filtering in Frequency Domain Time 12

13 JUNO s Multi-Calorimetry JUNO relies on large (20 ) PMTS to reach its physics goals Multi-Calorimetry: interleave large PMTS with small PMTS Large Pmt: Typically slower & poorer resolution B-field weak Large dark noise (huge photocatode) Main Calorimetry 1200 p.e./mev 75% photo-coverage stochastic term: 3%/ E ~0 p.e. /MeV % photocoverage stochastic > %/ E Small Pmts Faster (better transit time spread) High p.e. resolution B-field resistant High quantum & collection efficiency Low dark noise Time Reso & single photo-el. identification 13

14 Conclusions Conclusions JUNO R&D is proceeding at full speed (data taking expected in 2020) Great chance to do excellent Physics and give very relevant contribution (Simulation & Detector Design) Keep analyzing DayaBay data as a test bench for JUNO IHEP is the ideal laboratory where to carry out such experimental activities 14