Radioassay and Purification for Experiments at Y2L and Yemilab in - - PowerPoint PPT Presentation

Moo-Hyun Lee

Center for underground Physics, Institute for Basic Science (IBS), Korea

TAUP 2019 @ TIIC, Toyama, Japan

• 2019. 09. 09

Radioassay and Purification for Experiments at Y2L and Yemilab in Korea

Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

YangYang Pumped Storage Power Plant

Yangyang underground laboratory (Y2L) & CUP

Minimum depth : 700 m / Access to the lab by car (~2km) (Upper Dam)

(Lower Dam)

(Power Plant) COSINE-100 (WIMP Dark Matter) *DM12 AMoRE (0!"" Decay) *Neutrino17

Seoul Y2L

700m 1000m

Center for Underground Physics IBS (Institute for Basic Science)

CUP/IBS Daejeon A6: KIMS-CsI & HPGe A5: COSINE, AMoRE HPGe array, Alpha

Since 2003

Since 2014 3.3 hour driving 2.5 hour driving

3 AMoRE Experiment: 0!"" decay search

lSizable background case: l“Zero” background case:

When b is ~ O(1),

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

zero background non-zero background

AMoRE-I 5kg AMoRE-II 200kg

E b Mt A a N T

A

D = e

n

) 2 (ln (exp)

2 / 1

Sensitivity to half-life

• f 0νββ

Isotopic Abundance Atomic mass Background rate Energy Resolution Measurement time Detector Mass Detection Efficiency

Mt A a N T

A

e

n

) 2 (ln (exp)

2 / 1

=

AMoRE is aiming for zero background. 0!"" 2!""

Q## =3.03 MeV

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AMoRE Parameters

Radioassay and purification in Korea, Moo-Hyun Lee (IBS) TAUP2019@Toyama, 2019-09-09

¨ Crystals: 40Ca100MoO4(CMO) or XMO

(X: Li, Na, or Pb)

¤ 100Mo enriched: > 95% ¤ 48Ca depleted: < 0.001% (N.A. of 48Ca:0.187%)

¨ Low temperature detector: 10 – 30 mK ¨ Energy resolution: ~5 keV @ 3MeV ¨ Excellent PSD

Pilot Phase I Phase II Mass (Crystal) 1.9 kg CMO 6 kg (CMO + LMO) 200 kg XMO (X: Li, Na, Pb) BKG [keV .kg. year]-1 <10-2 <10-3 <10-4 T1/2 Sensitivity [years] ~1024 ~1025 ~8 ×1026 <mbb > Sensitivity [meV] 400 - 700 100 - 300 13 - 25 Location Y2L (700 m depth) Yemi Lab (1100m depth) Schedule 2015 - 8 2019 - 2021 2021 -

CMO LiMO PbMO

The AMoRE configuration and plan

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Identify critical radioactivity

Element Decay T1/2 Q (MeV) Mother Chain Comment

26Al

EC 7.4x105y 4.004 N/A Long lifetime

56Co

EC 0.21y 4.567 N/A Short lifetime

88Y

EC 0.29y 3.623

88Zr (0.23 y)

Short lifetime

106Rh

B- 30s 4.004

106Ru(1.02y) 126Sb

B- 12.5d 3.670

126Sn(2.3x105y)

Long lifetime

146Eu

EC 4.61d 3.878

146Gd (0.13 y)

Short lifetime

208Tl

B- 3.05m 4.999

228Th (1.91 y) 232Th

Main

209Tl

B- 2.16m 3.970

233U(159200y) 233U

2.1% branching

210Tl

B- 1.3m 5.482

226Ra(1600y) 238U

0.02% branching

214Bi

B- 19.9m 3.269

226Ra(1600y) 238U

Main

q Go through all known nuclei decaying ! with Q!! > 3.02MeV in NNDC database. q 110mAg (3.0105 MeV) doesn’t contribute for Mo experiment. q Cosmogenic excitation is negligible after 1 year at underground. q Only Th and U natural radio-activities are critical for Q> 3.02MeV. → Great advantage to run high Q-value nuclei !

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

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COSINE-100 instrument for WIMP DM search

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

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COSINE-100 NaI(Tl) crystal detector

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

q 8 ultra low-background NaI(Tl) crystals with a mass of 106 kg in total q U/Th/K levels are less than DAMA, but total alphas (210Pb) are higher than DAMA. q Higher light yield (15 p.e/keV) than DAMA q Can make the threshold lower easily q Total background level is 2-3 times that of DAMA.

Crystal Mass (kg) Powder Alpha rate (mBq/kg)

40K

(ppb)

238U

(ppt)

232Th

(ppt) Light yield (p.e./keV) Crystal 1

8.3 AS-B 3.20 ± 0.08 43.4 ± 13.7 < 0.02 1.31 ± 0.35 14.88 ± 1.49

Crystal 2

9.2 AS-C 2.06 ± 0.06 82.7 ± 12.7 < 0.12 < 0.63 14.61 ± 1.45

Crystal 3

9.2 AS-WS 0.76 ± 0.02 41.1 ± 6.8 < 0.04 0.44 ± 0.19 15.50 ± 1.64

Crystal 4

18.0 AS-WS 0.74 ± 0.02 39.5 ± 8.3 < 0.3 14.86 ± 1.50

Crystal 5

18.0 AS-C 2.06 ± 0.05 86.8 ± 10.8 2.35 ± 0.31 7.33 ± 0.70

Crystal 6

12.5 AS-WS 1.52 ± 0.04 12.2 ± 4.5 < 0.018 0.56 ± 0.19 14.56 ± 1.45

Crystal 7

12.5 AS-WS 1.54 ± 0.04 18.8 ± 5.3 < 0.6 13.97 ± 1.41

Crystal 8

18.3 AS-C 2.05 ± 0.05 56.15 ± 8.1 < 1.4 3.50 ± 0.33

DAMA

< 0.5 < 20 0.7 - 10 0.5 – 7.5 5.5 – 7.5

• Eur. Phys. J. C. 78 107 (2018)

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COSINE-100 Background Modeling

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

q Detector simulation based on GEANT4 well reproduces measured background spectra (4 channels for each crystal, single: 6 - 2000 keV, multiple: 2 - 2000 keV). q Main background in low energy region

− Contamination of crystals from 40K/U/Th − Cosmogenic activation (mostly 3H) − 210Pb on crystal surface

• Eur. Phys. J. C. 78 490 (2018)

multiple hit single hit single hit

9

Low Background Measurements at Y2L

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

¨ 2 HPGe detectors (2 Coax) ¨ 1 Array with 14 HPGe detectors ¨ Alpha ionization counter

A5 HPGe (CC1)

Alpha counter HPGe Array A6 A5 ~700 m deep

HPGe (CC2)

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Two single HPGe detectors: Screening of raw materials

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

CC1: 100% HPGe CANBERRA

Dedicated shielding: ‒ Top & bottom 10 cm Pb + 10 cm Cu (inner) ‒ Side 15 cm Pb + 10 cm Cu (inner) ‒ 5 cm thick ancient Pb closer to the detector Count rates of background (50−4000 keV) 8.1 mHz (2015), 7.9 mHz (2018), 7.8 mHz (2019)

CC2: 100% HPGe CANBERRA

Dedicated shielding: ‒ General Pb (10 cm) + Goslar Pb (10 cm) + Cu (10 cm) Count rates of background (50−3500 keV) 9.5 mHz (2017), 7.9 mHz (2018), 6.8 mHz (2019)

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HPGe measurement example (Iridium crucible)

q Iridium Crucible

for Mo based crystal growing

q Mass : 1627.4 g q Geometry:

100 (IR) x 100 (H) x 2(T) mm

q BKG : CC1 large volume (14 days)

Mass: 1.627 kg, Meas.day: 21 day @CC2

CMD246 IRIDIUM CRUCIBLE 190305

226Ra(238U) 40K 228Ac 228Th

17.44 ± 1.54 mBq/kg < 7.01 mBq/kg < 4.31 mBq/kg 5.04 ± 1.26 mBq/kg

192Ir

5.24 +/- 0.26 Bq/kg

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

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CC1 & CC2 measurements records

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS) Year Total AMoRE COSINE HPGe LZ Y2L Yemi R&D 2017 15 9 2 3 1 2018 17 10 5 1 1 2019 6 4 1 1 Year Total AMoRE COSINE HPGe LZ Y2L Yemi R&D 2017 21 7 11 3 2018 23 15 5 2 1 2019 11 7 1 2 1

CC1 CC2

§ Test duration of each sample is for 1-3 weeks depending on its purity. § HPGe had array materials, Ta and ThO2 samples measured § LZ for 8 inch PMTs § Y2L and Yemilab for rocks and shotcrete materials

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Array of 14 HPGe detectors

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

§ Developed in collaboration with CANBERRA. Operation from March 2017. § 2 ARRAYS placed one above the other with 7 HPGe (70% relative efficiency) each, total 980% with 14 HPGe detectors § Low background copper for endcap & holder. § O-rings were screened from more than 20 samples. § The sensitivity can be improved thanks to coincidence measurements. § Raw materials screening such as Mo-100 powder (AMoRE) or copper. § Rare decay search like 180mTa rare beta decay

14

Mo-100 powder (ECP) for AMoRE-II

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

Lot# Delivery@Y2L #1(3172) 3/9/16 #2(3328) 3434 12/28/16 3497 10/12/17 3535 3589 2/7/18 3649 5/29/18 3675 8/14/18 3741 2/13/19 3803 5/31/19 3824 8/20/19

100 kg delivered

• ut of 110 kg

Top Array Bottom Array Mo-100 powder bags 9771 g 2nd shipment

Last delivery ~Sep. 2019 HPGe Array meas. (9/13 – 11/28/2017) §

226Ra chain (238U) < 1.4 mBq/kg

§

228Th chain (232Th) = 0.55 ± 0.15 mBq/kg

§

88Y (cosmogenic) = 84 ± 18 !Bq/kg

1919 h data (1578 h BKG) with a total of 9618 g sample.

15

Alpha Counter

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

l An extremely sensitive alpha counter (argon gas

chamber) is purchased from XIA and installed at Y2L in summer 2015.

l Background rate : ~ 0.0001 alphas/cm2/hour. l Essential to study Pb-210 surface contamination

for DM experiment.

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q Po-210 depth is estimated at around 1.2+/-1.0 µm (stat. only) in the NaI(Tl) crystal. More accurate estimation requires to understand how particle diffusion happens in the surface.

How deep can Pb-210 penetrate in the NaI(Tl)?

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS) CUP Preliminary CUP Preliminary

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Ultra-sensitive Radon detector

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

§ Volume = 70 L § High Voltage = -1,000 V § Bias = 30 V § Stainless steel with electro-polished inside surfaces § Shaping amplifier with Í12 gain § 12 bit 25 MS/s FADC § Hamamatsu silicon PIN photodiode (S3204-9) 18 Í 18 mm2 § Hamamatsu charge sensitive amplifier (H4083) § HV divider circuit

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Pulse height distribution & RRS

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

• Pulse height distribution using

data taken at IBS HQ Daejeon.

• Crystal ball function is used for

all peaks.

• (Sigma) Resolution is less than or

equal to ~0.4 % for each peaks.

• Radon reduction system output at

Y2L was estimated 26.1 ± 5.6 mBq/m3@ Y2L (~1150 reduction factor).

• 226Ra calibration is currently on-

going at Daejeon.

218Po 214Po

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ICP-MS Lab at IBS HQ, Daejeon

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

q Agilent 7900, the highest sensitivity single MS system in 2015 when purchased. q Under operation since Oct. 2015. (Moved to IBS HQ in spring 2018) q In a cleanroom nominally designed as class 1000, >150 air changes/hour. q A Millipore DI system, in-house acid distillation with a 3 linear meters of chemical hood space. q Dissolve sample in liquid form, uptake in argon (Ar) gas stream, ionize gas, extract into mass spectrometer, measure trace contaminants. q Confirmation of purification methods by measuring isotopic or chemical tracers. q Confidence in systematics at ultra-trace levels is not easily achievable through outsourced measurements.

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condition Cool, 100ppm(dilution) Hot, He, 100ppm Hot, He, 1% with UHMI elements Al Al K Cr Cr Mn Mn Fe Fe Ni Ni Cu Cu Ti Ti Zn Zn W Sr Sr Ba Ba Pb Pb Th Th U unit ppb ppb ppb ppb ppb ppb ppb ppb ppb ppb ppt ppt ppt ppt ppt #3172

587 291 <300 <30 481 <25 <200 2437 <10000 44 1995 13011 5435 35 76

#3328

1818 1429 <300 <30 597 37 <200 1507 <10000 1213 4144 9521 4685 39 137

#3434

1889 1238 <300 <30 332 95 <200 1756 <10000 48 3034 18007 6986 87 214

#3497

1399 938 <300 <30 504 1073 <200 1802 <10000 670 4372 11183 3962 70 257

#3535

920 578 <300 <30 1486 64 <200 1666 <10000 202 30171 11194 6119 59 198

#3589

908 847 <300 <30 683 62 <200 1399 <10000 174 71978 11690 3274 50 113

#3649

720 519 <300 <30 528 55 <200 1584 <10000 165 22203 8821 7805 81 82

#3675

1104 705 <300 <20 969 226 1735 689 29825 9557 7376 91 75

Isotope ratio 92 92 94 94 95 95 96 96 97 97 98 98 100 100 #3172 0.024 0.017 0.030 0.035 0.028 2.881 96.984 #3328 0.016 0.011 0.022 0.026 0.026 3.137 96.761 #3434 0.015 0.010 0.019 0.023 0.022 3.692 96.218 #3497 0.016 0.011 0.021 0.025 0.024 3.267 96.635 #3535 0.016 0.011 0.021 0.024 0.023 3.310 96.595 #3589 0.013 0.009 0.017 0.020 0.021 3.300 96.620 #3649 0.014 0.009 0.017 0.020 0.021 3.318 96.600 #3675 0.029 0.020 0.036 0.041 0.035 3.527 96.313 (%)

100MoO3: ICP-MS measurements @ CUP

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

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Crystal growing optimization (Size and quality) Powder purification ICP-MS, HPGe, No Yes Crystal growing Scintillation (Phonon) No Yes Re-crystalization CUP chemical & clean room CUP & underground lab CUP lab. Y2L underground lab Baksan lab. Company (CUP lab.)

Ultra-low background powder R&D is difficult and need quick feedback (Purification and measurement of 10 !Bq/kg 238U, 232Th & total radioactivity of alpha < 1 mBq)

Ultra-low background crystals for AMoRE-II

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

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Low background Crystal growing facility at CUP

Radioassay and purification in Korea, Moo-Hyun Lee (IBS) TAUP2019@Toyama, 2019-09-09

¨ Main goal

¤ CaMoO4, Li2MoO4, Na2Mo2O7 crystals growing R&D for AMoRE-II ¤ Other DBD or DM crystal R&D

¨ Deep purification of CaCO3 and MoO3 powders ( < 50 µBq/kg for U,Th chain) ¨ Crystal growing equipment:

3 Czochralski, 2 Kyropoulous, 1 Bridgman crystal growers.

Czochralski machine (3 sets) CMO & LMO crystals by CUP

Sublimation device

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Molybdate crystals grown at CUP

Unpurified Mo and Ca powders

q Successful in growing molybdate crystals. Growing time ~ 1 week. q The purity of the grown crystals are measured by ICP-MS → Promising results q Enriched LMO crystals are grown at NIIC and CUP for LT measurements.

Purified Mo and Li powders

255.6 g, 100 mm (L) cut and polished

Purified Mo and Na powder TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

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Purities of CUP grown LMO crystals

Element Al K Ba Sr Pb Th U No. sample (ppb) (ppb) (ppb) (ppt) (ppt) (ppt) (ppt) Single crystallized natural LMO (w/o purification) CMD 113 L1701-1 48.1 347.3 5.445 <15 <300 <15 <16 CMD 113 L1701-2 21.7 449.2 5.401 75 <300 <15 <16 Single crystallized natural LMO (MoO3 sublimed) CMD163.1 CZ02-L1706-T <11 38 7.579 <50 <100 <8 <8 CMD163.2 CZ02-L1706-B <11 83 9.617 <50 <100 <8 <8 Double crystallized natural LMO (MoO3 sublimed) CMD191.1 CZ02-L1801-T <11 <30 4.744 <50 <100 <8 <8 CMD191.2 CZ02-L1801-B <11 <30 5.814 <50 <100 <8 <8 Enriched LMO (w/o purification) CMD00236.2 CZ02-L1803E-T 1437 <40 6.82 <31 <225 <6 <6 CMD00236.3 CZ02-L1803E-B 1484 <40 7.07 <31 <225 <6 <6 CMD00236.1 CZ02-L1803E-RM 3824 249 28.58 4110 12290 71 472 TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS) Single crystallized LMO (with purified MoO3) Double crystallized LMO (with 3 single crystallized LMO ) Polished LMO surface * See S.J. Ra’s poster

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Results for a natural CMO crystal growth at CUP

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

Li List st Al K Sr Zr Rh Ba Ir Pb Th U 99.9 .95 % CaCO3 81,5 ,500 20, 20,330 330 207,2 ,200

• 2,2

,270

• 510

510 33 33 880 880 99.9 .95 % MoO

• O3

1, 1,360 360 147,4 ,480 14.2 .2 306 306 <1 <10 992 992 0.0 .09 101.4 .4 1 2.7 .7 Natural CMO O (I (Ir) <6 <60 440 440 59,4 ,410 20 20

• 120

120 6.1 .1 6.6 .6 1.3 .3 9.3 .3 Pt Pt-Na Natural CMO 130 130 270 270 70,8 ,890 10 10 <2 <2,0 ,000 170 170 <0 <0.0 .05 5 0.8 .8 11 11 Pu Purified CaCO3 550 550 760 760 523,8 ,800 0.5 .5 <2 <2,0 ,000 2,3 ,300 <0 <0.2 .25 23.5 .5 0.3 .3 4.3 .3 Purified MoO

• O3

230 230 5,0 ,090 1.3 .3 0.5 .5 <1 <10 120 120 0.0 .02 4.7 .7 <0 <0.0 .01 0.1 .18 Purified CMO O (I (Ir) 120 120 320 320 83,8 ,890 0.2 .27 <2 <2,0 ,000 80 80 5.1 .1 0.1 .1 <0 <0.0 .01 0.0 .08

Unit: ppb * See S.J. Ra’s poster

26 AMoRE-II: Purification of XMO crystals

q Ba is a good indicator for Ra since they are in the same family. q We have a good progress toward AMoRE-II crystals.

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

27

AMoRE sensitivity for neutrino mass

q Seven commissioning runs in AMoRE-pilot have been completed in December 2018. q AMoRE-I is currently being prepared to start from this autumn. q AMoRE-II preparation is ongoing in parallel together with the Yemilab construction.

u Nuclear Matrix Element: QRPA

(Faessler et al., 2012)

u AMoRE-I: 5 kg and 5 years u AMoRE-II: 200 kg and 5 years u It was assumed as “zero-background”.

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

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Next Phase of COSINE(-200)

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

q Extremely pure crystal development

• Background level less than that of DAMA/LIBRA

(1 dru)

• In-house development for the entire processes
• Purification of NaI powder
• Full size crystal grower

q R&D of NaI(Tl) crystal at low temperature q Current COSINE-100 shield designed to accommodate sixteen of 12.5 kg crystals (200 kg).

Material Initial [ppb] Purified [ppb]

39K

45.1 6.0

208Pb

3.3 0.8

232Th

< 0.1 < 0.1

238U

< 0.1 < 0.1

• J. Rad. Nucl. Chem. 317 1329 (2018)

Crystal grade NaI [99.99(5) %]

Full size grower for ~ 100 kg ingot Purification factory for ~70 kg powder load

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COSINE-200 sensitivity (Modulation)

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS) ¨ 1 dru background (same as DAMA/LIBRA)

WIMP Mass (GeV) 1 10

2

10

3

10 )

2

SI WIMP-nucleon cross section (cm

44 −

10

43 −

10

42 −

10

41 −

10

40 −

10

39 −

10

38 −

10

37 −

10

) σ , 5 σ DAMA allowed region (90%C.L., 3 COSINE-200, 3 years of data , Median Sensitivty (90%C.L.)

ee

2-20 keV , Median Sensitivty (90%C.L.)

ee

1-20 keV

σ 1 ± σ 2 ±

7.3 sigma observation If DAMA is right..

200 kg × 3 year

(2-6 keV)

qModel independent comparison of the modulation amplitude at 2-6 keV will be performed.

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q The only operating iron ore mine in Korea. q A 600 m long 2nd shaft already constructed. q 0.7 million tons of iron ores extracted per year

Handeok has two shafts for mining 1st shaft ~ 300 m deep 2nd shaft 600 m deep (NEW)

Yemilab: A new underground lab in Handeok mine

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

Incheon airport

Airport à Handeok (3 hrs)

Handeok iron mine, Jeongseon, Korea

2nd shaft Now in operation q 4 major constructions Ø Tunnel excavation Ø Shaft cage Ø Underground lab Ø Surface office/lab

ARF is now Yemilab.

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Yemilab: Underground Laboratories

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

q 7 experiments with 12 spaces q 10 utility spaces

~ 1000m

Cross section of AMoRE Hall

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Start point entrance going down 780 m shaft

Yemilab: Tunnel excavation started in March

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

489 m

By mid. 2020

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Summary

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

q CUP has two major rare process experiments, AMoRE and COSINE, running in the Y2L. q CUP has been running ultra-low background measurements facility in the Y2L and IBS HQ to screen raw materials for the detector components from 2014. q AMoRE-II with 200 kg of crystals requires even lower background level of 10-4 ckky. q Purification and growing of molybdate crystals at the CUP started from 2016 aiming for the AMoRE-II and in a good progress. q COSINE-100 has 106 kg of NaI(Tl) crystals with similar or lower background levels in 40K/U/Th than those of the DAMA except 210Pb. It has 2-3 more background than that of the DAMA in low energy. q COSINE’s next phase is going to use ultra-pure NaI(Tl) crystals with ~200 kg mass to confirm/dispute the DAMA’s annual modulation in model-independent way. q Purification and crystal growing of NaI(Tl) started at the CUP from 2017 and in a good progress. q A new underground lab to accommodate the AMoRE-II, called Yemilab, has started its tunnel excavation from March to be completed by middle of 2020.

34

Backup slides

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)

35 HPGe measurement example (Vikuiti film)

Mass: 670g Meas. day: 44.8day

CMD038 VIKUITI 151002,151019

226Ra(238U) 40K 228Ac 228Th 210Pb

0.59 +/- 0.18 mBq/kg 9.35 +/- 2.35 mBq/kg < 0.93 mBq/kg < 0.64 mBq/kg < 46.04 mBq/kg

TAUP2019@Toyama, 2019-09-09 Radioassay and purification in Korea, Moo-Hyun Lee (IBS)