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

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

Sep 12, 2023 310 likes •553 views

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,

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SLIDE 1

Status of the COSINE-100 experiment at Yangyang

Chang Hyon Ha On behalf of the COSINE collaboration

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, July.12-20

8 low-radioactive NaI(Tl) crystals, 106 kg in total, submerged in 2 tons of liquid scintillator. Physics run started Sept. 2016

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SLIDE 2

Motivation : DAMA annual modulation signal, to be checked with independent measurements with the same NaI(Tl) target material

Dark Matter Modulation 9.2 sigma

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Modulation between 2-6 keV Background : ~1 count/day/kg/keV (dru=differential rate unit) above 2 keV NDM15

  • Eur. Phys. J. C (2010) 67: 39-49

NIMA 592 (2008) 297

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20

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SLIDE 3
  • Every scientific results should be reproducible, independently.
  • Apple-to-apple comparison is necessary.
  • Large crystal detector experience helps, and community supports.

Motivation : Right thing to do

  • Phys. Rev. D 94, 122001

3 Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20

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SLIDE 4

COSINE-100 experiment

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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 ICRC2017, Busan, Jul. 12-20

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SLIDE 5

Shields, Vetoes, and µ-counters

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Plastic Scintillators for CR Muons 3-cm thick, 37 panels 20-cm thick lead shielding 3-cm thick Cu box 40-cm active Liquid Scintillator veto NaI crystals 2-inch PMTs 5-inch PMTs 3-inch PMTs Neutron Detector

40 cm

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20

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SLIDE 6

Construction Timeline

  • Dec. 2015
  • Jan. 2016
  • Feb. 2016
  • Mar. 2016
  • Apr. 2016
  • May. 2016
  • Sep. 2016
  • Jun. 2016

6 Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20

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SLIDE 7

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COSINE-100 detector setup

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20

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SLIDE 8

COSINE-100 Operation

Very stable operation More than 85%

  • f physics data.

95% are good runs. Roughly 8 months data are collected Crystal Trigger Rate (13 Hz) Muon Detector Rate (12 Hz) Calibration

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20 8

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SLIDE 9

8 NaI(Tl) Crystals

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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.

210Po (210Pb) is still higher than DAMA.

Preliminary

3-inch PMT 35% QE

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20

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SLIDE 10

Crystal-LS Coincidence

  • 40K 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 efficiency)

γ (1460 keV) Liquid Scintillator

40K

e- (3 keV)

3 keV 40K peaks

Preliminary

+ Data (vetoed) – Fit – Subtracted 40K

10

Poster :: DM013, Govinda Adhikari

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20

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SLIDE 11

CR Muon detector system

COSINE-100 Preliminary

gamma background CR Muons

Muon flux monitor. CR muon induced crystal events are vetoed when muon pass through it.

4x10-7/cm2/s

COSINE-100 Preliminary

Poster :: DM017, Hafizh Prihtiadi

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20 11

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SLIDE 12

Low Energy Spectrum (

210Pb bkg.)

Internal components (crystal growing/raw material) : 210Pb (t1/2=22yr), U/Th External components (handling of crystal/material assay) 210Pb on the surface Cosmogenic components (excitation) : 125I (59d), 109Cd-109 (460d), 3H (12yr)

2-20 keV 2-100 keV

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2-4 dru (counts/day/kg/keV) between 2-6 keV

DAMA 1 dru

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20

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SLIDE 13

Understanding single-site event spectrum

— data — sim

210Pb (bulk) 210Pb (surf) 125I 109Cd 210Pb

(PTFE,Cu)

3H

Currently, 10-15% discrepancy at the ROI Goal <5%

COSINE-100 Preliminary

13

Poster :: DM012, Pushparaj Adhikari

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20

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SLIDE 14

Expected Sensitivity for COSINE-100

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*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 ICRC2017, Busan, Jul. 12-20

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SLIDE 15

COSINE-200 (Phase-II)

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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 ICRC2017, Busan, Jul. 12-20

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SLIDE 16

Expected sensitivity for COSINE-200 (Phase-II)

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20 16

*Assumed 1 dru flat backgrounds

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SLIDE 17

Conclusion & Outlook

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  • 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 ICRC2017, Busan, Jul. 12-20

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SLIDE 18

BACKUP

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SLIDE 19

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Environmental control/monitoring

Temperature Humidity

  • < 0.1˚C temperature fluctuation
  • n the crystals in LS
  • more than 150 environmental

variables are monitored online

Current/Voltage

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20

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SLIDE 20

High Energy Spectrum

100-2000 keV

— data — sim U/Th/K/Cosmogenics

20 Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20

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SLIDE 21

Liquid Scintillator for COSINE-100 is ready

21

3000 liters of liquid scintillators Purification Setup (Humidity removal)

Linear alkylbenzene (LAB) : Good optical/radioactive properties 2,5-Diphenyloxazole (PPO) : fluor, scintillator/wavelength shifter p-bis-(o-methylstyryl)-benzene (bis- MSB) : wavelength shifter

Ready to be filled

U238 < 7 ppt Th232 < 4 ppt

Rn222 daughters

This background of the liquid scintillator contributes negligible amount to the crystal (<0.01 dru)

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20

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SLIDE 22

Global NaI(Tl) efforts

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

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SLIDE 23

Event selection efficiency measured with

60Co Compton beta events Above 2 keV, more than 90% selection efficiency Hardware trigger threshold ( 0.14 keV ) LS Beta spectrum

  • btained by multiple-site

events using 60Co source

Ratio of event selection applied to triggered events

COSINE-100 Preliminary

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Poster :: DM027, Hanwool Joo

Chang Hyon Ha, Center for Underground Physics, IBS ICRC2017, Busan, Jul. 12-20