Status of the COSINE-100 experiment at Yangyang 8 low-radioactive - PowerPoint PPT Presentation

Status of the COSINE-100 experiment at Yangyang 8 low-radioactive NaI(Tl) crystals, 106 kg in total, submerged in 2 tons of liquid scintillator. Physics run started Sept. 2016 Chang Hyon Ha On behalf of the COSINE collaboration Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, July.12-20

Motivation : DAMA annual modulation signal, to be checked with independent measurements with the same NaI(Tl) target material Dark Matter Modulation 9.2 sigma NDM15 NIMA 592 (2008) 297 Eur. Phys. J. C (2010) 67: 39-49 Background : ~1 count/day/kg/keV (dru=differential rate unit) Modulation between 2-6 keV above 2 keV Chang Hyon Ha, Center for Underground Physics, IBS 2 ICRC2017, Busan, Jul. 12-20

Motivation : Right thing to do Phys. Rev. D 94 , 122001 • Every scientific results should be reproducible, independently. • Apple-to-apple comparison is necessary. • Large crystal detector experience helps, and community supports. Chang Hyon Ha, Center for Underground Physics, IBS 3 ICRC2017, Busan, Jul. 12-20

COSINE-100 experiment Joint collaboration between KIMS and DM-Ice to search for dark matter interactions in NaI(Tl) scintillating crystals. + Chang Hyon Ha, Center for Underground Physics, IBS 4 ICRC2017, Busan, Jul. 12-20

Shields, Vetoes, and µ-counters 3-inch 5-inch PMTs Plastic Scintillators for CR Muons PMTs 3-cm thick, 37 panels 40 cm 2-inch PMTs NaI crystals 3-cm thick Cu box 20-cm thick lead shielding 40-cm active Liquid Scintillator veto Neutron Detector Chang Hyon Ha, Center for Underground Physics, IBS 5 ICRC2017, Busan, Jul. 12-20

Construction Timeline Dec. 2015 Jan. 2016 Feb. 2016 Mar. 2016 Apr. 2016 May. 2016 Jun. 2016 Sep. 2016 Chang Hyon Ha, Center for Underground Physics, IBS 6 ICRC2017, Busan, Jul. 12-20

COSINE-100 detector setup Chang Hyon Ha, Center for Underground Physics, IBS 7 ICRC2017, Busan, Jul. 12-20

COSINE-100 Operation Crystal Trigger Rate (13 Hz) Muon Detector Rate (12 Hz) Very stable operation More than 85% of physics data. 95% are good runs. Roughly 8 months data Calibration are collected Chang Hyon Ha, Center for Underground Physics, IBS 8 ICRC2017, Busan, Jul. 12-20

8 NaI(Tl) Crystals Preliminary 3-inch PMT 35% QE 8 crystals with a total mass of 106 kg Internal background components are measured. Average light yield ~15 PE/keV U/Th/K contaminations are below DAMA value. 210 Po ( 210 Pb) is still higher than DAMA. Chang Hyon Ha, Center for Underground Physics, IBS 9 ICRC2017, Busan, Jul. 12-20

Crystal-LS Coincidence 3 keV 40 K peaks γ (1460 keV) + Data (vetoed) – Fit 40 K – Subtracted 40 K e - (3 keV) Preliminary Liquid Scintillator 40 K emits 1460 keV gamma with 3 keV Auger electron energy deposition • in NaI crystal • Tagging 1460 keV events with LS enables to veto 3 keV background events (70% tagging e ffi ciency) Poster :: DM013, Govinda Adhikari Chang Hyon Ha, Center for Underground Physics, IBS 10 ICRC2017, Busan, Jul. 12-20

CR Muon detector system COSINE-100 Preliminary CR Muons COSINE-100 Preliminary gamma background Muon flux monitor. CR muon induced crystal 4x10 -7 /cm 2 /s events are vetoed when muon pass through it. Poster :: DM017, Hafizh Prihtiadi Chang Hyon Ha, Center for Underground Physics, IBS 11 ICRC2017, Busan, Jul. 12-20

210 Pb bkg.) Low Energy Spectrum ( 2-20 keV 2-100 keV DAMA 1 dru 2-4 dru (counts/day/kg/keV) between 2-6 keV Internal components (crystal growing/raw material) : 210 Pb (t 1/2 =22yr), U/Th External components (handling of crystal/material assay) 210 Pb on the surface Cosmogenic components (excitation) : 125 I (59d), 109 Cd-109 (460d), 3 H (12yr) Chang Hyon Ha, Center for Underground Physics, IBS 12 ICRC2017, Busan, Jul. 12-20

Understanding single-site event spectrum — data COSINE-100 Preliminary 210 Pb (bulk) 210 Pb (PTFE,Cu) — sim 210 Pb (surf) 125 I 109 Cd 3 H Currently, 10-15% discrepancy at the ROI Goal <5% Poster :: DM012, Pushparaj Adhikari Chang Hyon Ha, Center for Underground Physics, IBS 13 ICRC2017, Busan, Jul. 12-20

Expected Sensitivity for COSINE-100 *Assumed 2 dru or 4 dru flat backgrounds depending on crystals. The sensitivity should be comparable with the DAMA allowed region. Chang Hyon Ha, Center for Underground Physics, IBS 14 ICRC2017, Busan, Jul. 12-20

COSINE-200 (Phase-II) Goal : Reaching background lower than DAMA (1 dru). a factor two or more improvement is needed. Powder purification (Recrystallization) Crystal growing & Handling Established a facility at our center Powder purification (mass production facility for purification under construction) Chang Hyon Ha, Center for Underground Physics, IBS 15 ICRC2017, Busan, Jul. 12-20

Expected sensitivity for COSINE-200 (Phase-II) *Assumed 1 dru flat backgrounds Chang Hyon Ha, Center for Underground Physics, IBS 16 ICRC2017, Busan, Jul. 12-20

Conclusion & Outlook • KIMS and DM-Ice join forces (the COSINE-100 collaboration) to reproduce DAMA annual modulation using the same NaI(Tl) target material. • COSINE-100 (Phase-I) is running with 106 kg of NaI(Tl) crystals. • CR muon tagging and liquid scintillator tagging. • Physics run started on September 2016 • Initial performance of COSINE-100 is promising. 2 keV thres., 2-4 dru at ROI • Expect to have DAMA-comparable sensitivity in ~2 years • Continued R&D for higher purity crystals for COSINE-200 (Phase-II) Chang Hyon Ha, Center for Underground Physics, IBS 17 ICRC2017, Busan, Jul. 12-20

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Environmental control/monitoring Temperature Humidity • < 0.1˚C temperature fluctuation on the crystals in LS • more than 150 environmental variables are monitored online Current/Voltage Chang Hyon Ha, Center for Underground Physics, IBS 19 ICRC2017, Busan, Jul. 12-20

High Energy Spectrum 100-2000 keV U/Th/K/Cosmogenics — data — sim Chang Hyon Ha, Center for Underground Physics, IBS 20 ICRC2017, Busan, Jul. 12-20

Liquid Scintillator for COSINE-100 is ready Linear alkylbenzene (LAB) : Rn222 Good optical/radioactive properties daughters 2,5-Diphenyloxazole (PPO) : fluor, scintillator/wavelength shifter p-bis-(o-methylstyryl)-benzene (bis- MSB) : wavelength shifter U238 < 7 ppt Th232 < 4 ppt Purification Setup (Humidity removal) 3000 liters of liquid scintillators This background of the liquid scintillator contributes negligible amount to the crystal (<0.01 dru) Ready to be filled Chang Hyon Ha, Center for Underground Physics, IBS 21 ICRC2017, Busan, Jul. 12-20

Global NaI(Tl) efforts DAMA/LIBRA @ LNGS COSINE-100 @ Y2L SABRE @ LNGS PICO-LON @ Kamioka ANAIS @ Canfranc SABRE @ Stawell DM-Ice17 @ South Pole Chang Hyon Ha, Center for Underground Physics, IBS 22 ICRC2017, Busan, Jul. 12-20

Event selection efficiency measured 60 Co Compton beta events with LS Ratio of event selection applied to triggered events Beta spectrum obtained by multiple-site COSINE-100 Preliminary events using 60 Co source Above 2 keV, more than 90% selection efficiency Hardware trigger threshold ( 0.14 keV ) Poster :: DM027, Hanwool Joo Chang Hyon Ha, Center for Underground Physics, IBS 23 ICRC2017, Busan, Jul. 12-20