Latest Results from the CUORE Experiment
Pranava Teja Surukuchi(for the CUORE collaboration)
Aug 22, 2021

XX Lomonosov Conference on Elementary Particle Physics

Neutrinoless Double Beta Decay (0νββ)• Hypothesized nuclear process - Neutrinoless counterpart to observed double betadecay• If observed, implies:• ν is Majorana fermio• Lepton number violatio• Hints to matter-antimatter asymmetr

103

210

• Constrain the ν mass and orderingm ββ (meV)αCurrent limits
102

Inverted hierarchy
1010Normal hierarchy
1Phase space factor ynnPranava Teja Surukuchi, Lomonosov Conference, Aug 2021 1Effective neutrino mass

Important to observe 0νββ in multiple isotopes 3Mo• 0νββ experiments measure half-life (or decay rate)

Nuclear Matrix elements

1010−110−1

10110−11020m lightest (meV)

2Oth0.2

CUORE
Cryogenic Underground Observatory for Rare Events• Located in LNGS under the mountain of Gran Sass<latexit sha1_base64="fJCquNoGyKWN+X/bYHxcirsVkgc=">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</latexit>• Primary Goal: Search for 0νββ decay in 130T

S0⌫ / Na ✏•Design• 19 towers (total of 988 TeO2 crystals• Large mass: 742 kg of TeO2 ,206 kg of 130TerMt
B E• Qββ (2528 keV) - above most γ natural radioactivit• Isotope within the absorbe• Low background goal: 10-2 cts/(keV. kg. yr• Energy resolution: Goal of 5 keV FWHM at Qββ• High efficiency and duty cycle•Sensitivity• T0v1/2 ~ 9 x 1025 yrs (90% C.L) in 5 yr
• mββ < 50-130 meVoye ))s r::Pranava Teja Surukuchi, Lomonosov Conference, Aug 2021

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Calorimetric Technique
Crystal temperature rises when energy is deposited• Each crystal• Absorber: 5x5x5 cm3 TeO2 crysta• Operational temperature: ~10 m• Thermal coupling: PTFE holde• Sensor: Ge neutron transmutation doped (NTD) thermistoHeater3200

ΔT α E/C(TC(T) α Τ32800
2600
2400
2200
2000

ΔT ~ 100 μK

3000

Α.UAmplitude [mV]

• Heater: Gain calibration• Excellent energy resolution (~0.2% ΔΕ/E FWHM)~1 MeV• Detector response independent of particle type

1s

1800
1600
00.5

1

• Flexibility in 0νββ candidate choice

1.5

2

2.5

33.5
4Time [s]Timer  Klr)

:Pranava Teja Surukuchi, Lomonosov Conference, Aug 2021

4CUORE Cryostat• Multiple stage cryogen-free cryostat• Nested co-axial cylinder• Pulse Tubes for cooling 40 K and 4 K stage• Dilution Unit to cool rest of the stages• Total mass: ~30 tonne; ~1 tonne @ 10 m
• Background mitigation• 3600 meter water equivalent natural overburde• Passive lead, polyethylene, and H3BO3 shielding• Careful material selection and radiopure control• Active background reduction from event selection

Low background cryostat maintained at low temperature with minimal vibrations
sn s

K :sPranava Teja Surukuchi, Lomonosov Conference, Aug 2021

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Data Taking• Jan 2017: Data taking starte• 2017-2019: Low duty cycle detector optimization and upgrade• Since 2019: Continues data taking with low downtime (~92% duty cycle

Since Spring 2019

Exposure Accumulation - July 2021
Analyzed
exposure
Total arXiv:2104.06906
collected exposure1200

PRL 124.122501 (2020)

1000
800

0.9 %%
2.3

600

11.7 %

12.2 %

400

Background
Down Time
Setup

Calibration
NPulses
Test

200
0400
350
300
250

Dilution system
upgrade & EDCS
installation
Vacuum leakrepairJul-2017 Dec-2017 Jul-2018 Dec-2018 Jul-2019 Jan-2020 Jul-2020 Dec-2020 Jul-2021

13065.3 %

1400

PRL 120.132501 (2018)

Exposure (kg⋅yr)

kg.yr)• 15 datasets analyzed (1038.4CUORE Run Time Breakdown

Te Exposure (kg⋅yr)• 18 datasets completed; each dataset ~1 month long (~ 1400 kg.yr data collected

200150100500Stable data taking by CUORE since early 2019))

sdPranava Teja Surukuchi, Lomonosov Conference, Aug 2021

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Average puls
Filtered pulse

Trigger

Channels

Analysis Chain
70

Analysis threshold60

OT trigger thresholds

50
40

CUORE Preliminary

30

Continuous data collected
and saved for offline trigger

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Amplitude evaluation

208Tl 228Ac

e+e228Ac
60Co60Co

CUOREPreliminary

208Tl

208Tl

100020406080CUORE Preliminary

100

Reconstructed Energy (keV)

Gain stabilization
Energy calibration
Multiplicity cutPSA

CUORE Preliminary

BlindingeePranava Teja Surukuchi, Lomonosov Conference, Aug 2021

7Counts / (keV kg yr)

Spectrum: All Datasets
210

Base Cuts
Base Cuts + AC
Base Cuts + AC + PSD

60Co 40K

10−11010210Po

Q
208 ββTl

214Bi

Dominated by 2νββγ Background region−2Exposure: 1038 kg.yr

190Pt

Qββ
1

CUORE Preliminary

1000

α Background region
2000

3000

4000

5000

6000

Energy (keV)
Pranava Teja Surukuchi, Lomonosov Conference, Aug 20218

Detector Response and Efficiency•Fit to 208Tl peak

Detector response modeled based on a fit to 2615 208Tl peak

1.4
1.3
1.2

Ratio

1.1
1
0.9
0.8

• Parametrized by 3 Gaussian peaks + X-ray escape + flat background + multi-Compton pea

0.7
0.6
2540

2560

2580

2600

2620

2640

• Efficiencies determined using a combination of MC, heaters and single-site radioactive decays

Counts/ (2 keV)

• Determine energy bias and resolution scaling to Qββ by scaling this to peaks in physics dat

10Heater 96.418 ± 0.002 %40K

Dataset
level

2720

multiCompton

Flatbackground
2540

2560

2580

2600 2620 2640 2660
Reconstructed Energy (keV)

2680

2700

2720

88.35 ± 0.09 %99.3 ± 0.1 %FWHMPhysics/FWHMCalibration

Crystal
level

2700

2615+X-ray

310102MC

X-ray
escape peak

104

2680

CUOREPreliminary

5102660

1.1

CUORE Preliminary

1Single Dataset

0.9
0.8
0.7
0.6
0.5
0.4

40

discrimination

M1

2x60
208Tl

500

1000

1500

2000

96.4 ± 0.2 %2500
Energy (keV)

FWHM at 2615 keV in calibration data - 7.78(3) keV

Total analysis efficiency 92.4 ± 0.2%

FWHM at Qββ in physics data - 7.8(5) keV
Bias at Qββ < 0.7 keVakCKPranava Teja Surukuchi, Lomonosov Conference, Aug 2021

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Fit to ROI• Unbinned Bayesian fit using Bayesian Analysis Toolkit (BAT• Fit region: [2490, 2575] keVSystematics:• Analysis efficiencie• Containment efficienc• Energy scal
• Energy resolutio• Qββ• 130Te abundance

Fit parameters:• 0νββ decay rate @ 2527.518 ke• 60Co sum peak amplitud• Background index• Background slope• Systematics implemented as nuisance parameter• No evidence of 0νββ
• Best fit rate: (0.9 ± 1.4)x10-26 yr-1
• Background index = 1.49(4)x10-2 cts/keV/kg/yr-2• T0ν1/2 > 2.2 x1025 yr at 90% C.

110Best fit (global mode)
90% CI limit on Γ0ν
Fit without 0νββ component

100
9080

CUORE Preliminary

70Exposure: 1038 kg.yr

60
50
40

Number of Experiments

Counts / (2.5 keV)

• Median expected T0ν1/2 = 2.8 x1025 yr at 90% C.I

600500CUORElimit

arXiv:2104.06906300
200Mediansensitivity

300020Energy (keV)) sVIe ys  ne Pranava Teja Surukuchi, Lomonosov Conference, Aug 2021 Exposure: 1038 kg.yr

4001002490 2500 2510 2520 2530 2540 2550 2560 2570

CUORE Preliminary

40×1024
60
80
100
90% C.I. limit on T1/2 [yr]10Limit on Effective Majorana Mass
103

10390% C.L.

CUORE Preliminary
Exposure: 1038.4 kg⋅yr• T0ν1/2 > 2.2 x1025 yr at 90% C.

CUORE limit (Te)2• Uncertainities in nuclear matrix
elements dominates the rang

10101010Normal hierarchy
11−1−11010−110110m lightest (meV)
Pranava Teja Surukuchi, Lomonosov Conference, Aug 2021
IXe

Inverted hierarchy• Sensitivity (5 yr data taking):
130Te T0ν1/2 > 9.0 x1025 yr
mββ < 50 - 130 meVeGe

2CUORE sensitivity (Te)m ββ (meV)• Assuming light neutrino exchange:mββ < 90 - 305 meV

Mo Se

Other isotopes
21000.20.4

0.60.8

1arXiv:2104.06906
11• 2νββ decays deposit energy primarily (~90%) in a single
channel while backgrounds deposit in multiple channel• Develop CUORE background model: 60 radioactive
contaminants + muons + 2νββCounts / (keV kg yr)

130Te 2νββ Decay Half-life
102

Base Cuts
Base Cuts + AC
Base Cuts + AC + PSD

10CUORE Preliminary
Exposure: 1038 kg.yr

Q ββ

1

10−1

10−2

1000

2000

3000

4000

5000

6000

Energy (keV)• Perform simultaneous Bayesian fit to 62 MC simulatedspectr• 2νββ rate extracted as marginalized posterior PD• Most precise measurement of 130Te half-life withexposure of 300.7 kg·y
PRL:126.171801• Refined background model in preparation

T2ν1/2 (130Te) = 7.71 + 0.08 (stat) +0.12 (syst) -0.06(stat) -0.15(syst) x 1020 yrsFraPranava Teja Surukuchi, Lomonosov Conference, Aug 2021

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CUPID: CUORE Upgrade with Particle Identification• ~1596 Li2100MoO4 scintillating crystals (~250 kg of 100Mo)• Instrument each crystal with a light detector for particle
ID• Use existing CUORE cryosta• Low background targeted (10-4 cts/keV/kg/yr)• Active α discriminatio• Qββ = 3034 keV (above all gamma backgrounds• Muon veto syste• Builds on experience from CUPID-0 and CUPID-M• Projected sensitivity: 12 - 20 meV with ~ 240 kg of100M• Improvement in sensitivity and change in isotopes possible :O)

tnmo Pranava Teja Surukuchi, Lomonosov Conference, Aug 2021

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Conclusions• CUORE is the largest ultra-cryogenic calorimeter searching for 0νββ
• CUORE started data taking in 2017 and continuing stable data taking since early 2019 at ~ 50kg.yr/month• More than 1 tonne.yr data analyze• Limits placed on 130Te T0ν1/2 > 2.2 x1025 yr and mββ < 90- 305 meV• T2ν1/2 = 7.71 x 1025 yr measured; most precise measurement so far• CUORE paves way for the next generation cryogenic 0νββ experiments (CUPID)

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Thank you

Pranava Teja Surukuchi, Lomonosov Conference, Aug 2021

Pranava Teja Surukuchi, Lomonosov Conference, Aug 2021

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