Status of Neutrino Elastic-scattering Observation with NaI(Tl) (NEON)

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Status of Neutrino Elastic-scattering Observation with NaI(Tl) (NEON)

In-Soo Lee

Center for Underground Physics (CUP) Institute for Basic Science

On behalf of the NEON collaboration

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Motivation – 𝐂𝐂𝐂𝐂𝝂𝝂𝐍𝐍𝐍𝐍 with NaI(Tl)

• Coherent Elastic Neutrino Nucleus Scattering (𝐂𝐂𝐂𝐂𝝂𝝂𝐍𝐍𝐍𝐍)

• Predicted at 1974

• First measurement by the COHERENT collaboration

• Physics ?

• Neutrino magnetic moment

• Neutrino non-standard interaction

• Neutrino-electron scattering

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PRD 9, 1389 (1974)

Science 357, 1123-1126 (2017)

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Motivation – 𝐂𝐂𝐂𝐂𝝂𝝂𝐍𝐍𝐍𝐍 with NaI(Tl)

• Coherent Elastic Neutrino Nucleus Scattering (𝐂𝐂𝐂𝐂𝝂𝝂𝐍𝐍𝐍𝐍)

• Predicted at 1974

• First measurement by the COHERENT collaboration

• N eutrino E lastic-scattering O bservation with N aI(Tl) ( NEON )

• Aim to detect 𝐂𝐂𝐂𝐂𝝂𝝂𝐍𝐍𝐍𝐍 in reactors.

• Single flavor (electron anti-neutrino) & 𝑁𝑁²dependence

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PRD 9, 1389 (1974)

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Science 357, 1123-1126 (2017)

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NEON collaboration

• 16 members, 3 institutes

• Active members of the COSINE-100 and NEOS experiments

• Aim to observe 𝐂𝐂𝐂𝐂𝝂𝝂𝐍𝐍𝐍𝐍 from reactor 𝜈𝜈 �

_𝑒𝑒

using NaI(Tl) detector

• Low-background dark matter crystal experts (COSINE-100) + Reactor neutrino experiment experts (NEOS)

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NaI(Tl) for 𝐂𝐂𝐂𝐂𝝂𝝂𝐍𝐍𝐍𝐍

• High measured light yield (15 photo-electrons/keV in COSINE-100)

• Larger recoil energy from Na (𝑁𝑁² dependence testable.)

• Easy to make large size detector O(10 kg)

• Low background detector available (3 counts/kg/day/keV= 3 DRU)

• Easy to scale up with affordable costs O(100 kg)

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COHERENT

Full size grower @ CUP

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Reactor Neutrino 𝐂𝐂𝐂𝐂𝝂𝝂𝐍𝐍𝐍𝐍 rate on NaI(Tl) target

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• Assume the neutrino flux at NEOS site ( Φ

₀

= 7.1 × 10

¹²

cm

²

s

⁻¹

)

• COSINE0-100 quenching (light output/ energy deposit) is used.

• Light yield is key factor.

25 PEs/keV 20 PEs/keV 15 PEs/keV

𝐂𝐂𝐂𝐂𝝂𝝂𝐍𝐍𝐍𝐍cross section on NaI Event rate vs P.E.with Na quenching

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Sensitivity

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Reactor On Reactor Off

𝐂𝐂𝐂𝐂𝝂𝝂𝐍𝐍𝐍𝐍 Model

Assumption

• 5 counts/kg/day/keV flat background

• 15-kg mass of detector

• 365/100 days reactor on/off data

• 22 photo-electrons/keV light yield

• 5 P.E.s threshold

Significance level 𝟒𝟒.𝟔𝟔±𝟎𝟎.𝟑𝟑𝝈𝝈

Sodium

~1.6 events/day/15 kg

Iodine

Signals : 𝟓𝟓𝟒𝟒𝟓𝟓.𝟔𝟔±𝟏𝟏𝟏𝟏𝟓𝟓.𝟔𝟔

Single pseudo experiment Expected signals

1000 pseudo experiments

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𝟑𝟑𝝈𝝈 5𝝈𝝈

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Sensitivity

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Assumption

• 22 photo-electrons/keV light yield

Significance level 𝟒𝟒.𝟔𝟔±𝟎𝟎.𝟑𝟑𝝈𝝈

Sodium

~1.6 events/day/15 kg

Iodine

Signals : 𝟓𝟓𝟒𝟒𝟓𝟓.𝟔𝟔±𝟏𝟏𝟏𝟏𝟓𝟓.𝟔𝟔

Single pseudo experiment Expected signals

1000 pseudo experiments

Requirement for NEON

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𝟑𝟑𝝈𝝈 5𝝈𝝈

Reactor On Reactor Off

𝐂𝐂𝐂𝐂𝝂𝝂𝐍𝐍𝐍𝐍 Model

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NEON detector

• Optimizing detector assembly for high light yield

• Direct contact between crystal and PMT

• No quartz window

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COSINE-100 Encapsulation Silicon gel Quartz glass Optical Ped

Optical Ped

NEON Encapsulation

Am241 calibration@ Y2L underground Lab.

• Achieve ~22 P.E./keV !!

• 5 P.E. ~ 0.22 keV

Nucl. Instrum. Meth. A 981 (2020) 164556

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NEON detector cont’d

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• Total 15 kg 6 Commercial Crystals

• Light Yield : 20~24 NPE/keV

• NEO-1,2,3 (1.64 kg)

• NEO-4,5,6 (3.37 kg)

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Shielding design

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• 20 cm Poly-Ethylene + 5 cm Borated-Poly-Ethylene + 10 cm Lead for radiation shield

• ~ 700L Liquid scintillator (LS) in 1 m x 1 m x 1 m box for active veto

• 2 Calibration pipes

Poly-Ethylene (20 cm) Borated Poly-Ethylene (5 cm) Led (10 cm)

LS

Calibration pipe

Reactor direction

~15 kg NaI crystals

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Calibration

• Energy calibration with ^{𝟏𝟏𝟒𝟒𝟏𝟏}𝐀𝐀𝐀𝐀

• Low-energy

scintillation samples with ^{𝟏𝟏𝟏𝟏}𝐍𝐍𝐍𝐍

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𝟏𝟏𝟒𝟒𝟏𝟏𝐀𝐀𝐀𝐀calibration data ^{𝟏𝟏𝟏𝟏}𝐍𝐍𝐍𝐍calibration data

𝟏𝟏𝟒𝟒𝟏𝟏𝐀𝐀𝐀𝐀and ^{𝟏𝟏𝟏𝟏}𝐍𝐍𝐍𝐍sources

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60 keV ^{511 keV}

1275 keV

Calibration pipe

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Proto-NEON experiment

@ ground office

• Install NEON detectors @ ground office (sea level laboratory)

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• Measurement (July~Oct 2020)

• DAQ test & debugging

• Calibration with ²⁴¹Am and ²²Na

• Background measurement

NEON DAQ 13

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Proto-NEON experiment

@ ground office

• Achieve 1 keV thresholds using

^{𝟏𝟏𝟏𝟏}

𝐍𝐍𝐍𝐍 source data

• Single hit background ~3 DRU @5-20 keV with LS veto

• Background modeling study is on-going.

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125I ²¹⁰Pb

125I

NEO-5 crystal (3.3 kg size) Energy VS BDT with ²²Na^source _Backgroundenergy distribution

Preliminary

1 keV

Preliminary

Single hit Multiple hit

Noise Noise

Scintillation Scintillation

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cont’d

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Hanbit Nuclear Power plant

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• 2.8 GW thermal power

• Tendon gallery is ~24 m from reactor core

• Well known environmental conditions from NEOS experiment

• Neutrino flux Φ₀ = 7.1 × 10¹²cm²s⁻¹

1 2

3 4 5 6

Yeonggwang Hanbit Nuclear Power plant (Reactor 6) Tendon gallery

Neutrino flux at NEON site : 𝟕𝟕.𝟏𝟏×𝟏𝟏𝟎𝟎^{𝟏𝟏𝟏𝟏}𝐜𝐜𝐀𝐀^−𝟏𝟏𝐬𝐬^−𝟏𝟏

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NEOS NEON

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NEON Installation

• NEON detector and DAQ were installed at Nov. 26 in 2020

• Start physics run from 2020.12.04

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Nov 12 2020

Nov 26 2020

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2020-4 2021-1 2021-2 2021-3 2021-4

ProtoNEON Physic run

Reactor On Reactor off Reactor On

Operation status

• ~ 2 month shielding upgrade in order to reduce PMT noise

• From PMT electronics contamination by LS

• Add acrylic box btw LS and Crystals

• ²²Nacalibration run July~ Aug

• Reactor on data ~ 4 months

• Reactor off data ~ 1 week (190 hours)

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Installation Shielding update Encapsulation upgrade (plan)

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Acrylic box isolating from LS

Upper LS tank

Crystal tank

Holes for calibration pipes

𝟏𝟏𝟏𝟏𝐍𝐍𝐍𝐍calibration run

LS

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Monitoring

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Data Quality Monitoring Environment Monitoring

Trigger rate

HV

Temperature

Humidity

UPS

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Preliminary background spectrum

^@Reactor

• Apply proto-NEON BDT selection

• Single hit background ~5 DRU @5-20 keV with LS veto

• Low threshold and background modeling study is ongoing.

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Reactor off data (NEO-5 crystal )

Preliminary

Single hit Multiple hit

Noise Scintillation Noise Scintillation

1 keV

Energy VS BDT (Reactor off)

Preliminary

Energy distribution (Reactor off) Preliminary

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Schedule for the NEON Experiment

• NEON-phase1 (~2023)

• ~15 kg commercial crystals

• Next reactor off : Aug. 2023

• Demonstration of detector performance and observe CE𝜈𝜈NS with > 3𝜎𝜎

• NEON-phase2 (~2025)

• ~100 kg purified crystals ( < 1 counts/kg/day/keV background)

• Precision measurement and explore new physics interaction

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2019 2020 2021 2022 2023 2024 2025

Detector development

NEON-phase 1

NEON-phase 2

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Summary

• NEON experiment aims to detect CE 𝜈𝜈 NS using NaI(Tl) from reactor electron -antineutrino which has important role to

provide other new physics such as neutrino magnetic moment and non-standard interactions.

• We satisfied most requirements and study is ongoing for the rest.

• 22 photo-electorns/keV light yield

• NEON-phase 1 is now installed in Hanbit reactor in Dec. 2020

• Physics run starts from Dec/2020.

• Data taking is operating stably after upgrade shielding

• ~ 4 months Reactor on data

• ~ 1 week (190 hours) Reactor off data

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Back up

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NEON DAQ

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Anomalous noise @ reactor

• Unexpected noise in all crystals @ reactor

• Noise from PMT electronics contaminated by L.S.

• Interrupt to distinguish crystal signal and PMT noise

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Anomalous noise waveform

Crystal signal waveform

MeanTime VS Energy (Reactor)

PMT noiuse

MeanTime (ns)

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New acrylic boxes structure

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Upper LS tank

Crystal tank Holes for calibration pipes

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