GERDA, MAJORANA and LEGEND - towards a background-free ton-scale Ge-76 experiment - INDICO-FNAL
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GERDA, MAJORANA and LEGEND
towards a background-free
ton-scale Ge-76 experiment
Yoann KERMAÏDIC
for the GERDA, MAJORANA and LEGEND collaborations
XXIX International Conference
on Neutrino Physics
Virtual meeting
July 2020
Physics case: neutrinoless !! decay
Search for a natural double beta decay
without the standard emission of two anti-neutrinos (0#!!)
n
n
n p
$%
?
$%
n p
0#!! decay is a search for lepton number violation:
☞ sheds light on Majorana nature of neutrinos
☞ tests theories with lepton number violating interactions
☞ constrains baryon asymmetry scenarios
!! decay is energetically favoured in many isotopes:
76Ge – 82Se – 100Mo – 130Te – 136Xe – …
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 2
0#!! experimental signature in 76Ge
Counts /(keV.kg.yr)
Counts /(keV.kg.yr)
R (T=U)
0.06
X = @A 0.04
1
0.02
26.3 h 0 1800 1900 2000
Energy (keV)
EF
DDAs
-1
?×OP?O Q
10
2 !%
@A
>?
Outline
76
Ge (88% enr.)
1030
long-term
LEGEND 1029
M ton
1000 XNY
M/= > MN
=[ yr
1028
T1/2 3s DS [years]
LEGEND mid-term
1027
200 =NN kg
XNY
M/= > MN
=> yr
1026 IO mmin
bb
range
GERDA Background free
MAJORANA 0.1 counts/FWHM-t-y
running/ended
1025 1.0 count/FWHM-t-y MN
=? yr
1024 -3
10-2 10-1
3
10 1 10 102 10
Exposure [ton-years]
1. Status of MAJORANA and GERDA data taking
new results
2. Joint worldwide community: LEGEND at this conference!
3. Prospective towards a ton-scale experiment
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 4
MAJORANA DEMONSTRATOR
Searching for neutrinoless double-beta decay
of 76Ge in HPGe detectors and additional
physics beyond the standard model
Source & Detector: Array of p-type, point contact
detectors
29.7 kg of 88% enriched 76Ge crystals
Excellent Energy resolution: 2.5 keV FWHM @ 2039 keV
Low Background: 2 modules within a compact graded
shield and active muon veto using ultra-clean materials
Operating underground at the 4850’ level of the Sanford Underground Research Facility since 2015
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 5
MAJORANA DEMONSTRATOR 2019 0νββ Result
Operating in a low background regime and benefiting from excellent energy resolution
Initial Release:
9.95 kg-yr open data
PRL 120 132502 (2018)
26 kg-yr
Latest Release:
First unblinding of data
26 kg-yr exposure
PRC 100 025501 (2019)
Median T1/2 Sensitivity:
4.8 × 1025 yr
Full Exposure Limit:
T1/2 > 2.7 × 1025 yr (90% CL)
Background Index at 2039 keV
in lowest background config:
11.9 ± 2.0 cts/(FWHM t yr)
Latest result from 26 kg-yr (data up through April 2018)
An upcoming result with improved analysis and new data through Nov 2019
A combined total of ~50 kg-yr, a release later this summer
Upcoming new results on background model & beyond the standard model searches
A new result on excited state decays of 76Ge
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 6
MAJORANA: Progress and Improvements
Progress towards modeling the measured background Low-Background Datasets
M. Buuck, UW, PhD
Dissertation 2019
Enriched Detectors
Investigating source of excess backgrounds near Qββ DCR Cut Only
Preliminary findings point to 232Th backgrounds
distant from the array
A higher fidelity modeling of distant components is underway
See Poster 257: An Improved Background Model for the
MAJORANA DEMONSTRATOR (A. Reine, C. Haufe)
An upcoming result with improved analysis and new data through Nov 2019
A combined total of ~50 kg-yr, a release later this summer
Improved analysis
Improved energy estimator with a corrected waveform start time
Excellent energy resolution (2.5 keV FWHM at Qββ) ± 0.2 keV
and improved linearity
Enhanced the stability and uniformity of background rejection parameters
Improved discrimination power of the multisite (AvsE)
and surface alpha (DCR) cuts
See Poster 586: Status and Results from the MAJORANA DEMONSTRATOR
Status and run plan Experiment (J. M. López-Castaño, N. Ruof, A. Hostiuc)
2020 hardware upgrade
Improved the robustness of the signal and HV connections based New connectors
on an ultra-clean, low-mass, & high-reliability design
Deployment of larger inverted-coax point-contact detectors and
measure performance
Final running to yield an ultimate integrated exposure of ~60 kg-yr
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 7
MAJORANA: Beyond the Standard Model Searches
The low backgrounds, low threshold, high resolution spectra allows additional physics searches
Controlled surface exposure of enriched material to minimize cosmogenics
Upcoming updates to beyond the standard model searches
Excellent energy resolution: 0.4 keV FWHM at 10.4 keV Low-energy physics
Progress towards a low-E background model: searches
pseudoscalar dark matter
vector dark matter,
65Zn PRL 118 161801 (2017)
PRELIMINARY Best Fit
14.4-keV solar axion
55Fe
68Ge
Updated limits to be C. Wiseman, J. Phys. Conf.
210Pb
released after unblinding Ser. 1468, 012040 (2020)
3H
Search for tri-nuclean decay
A test of baryon number PRD 99 072004 (2019)
violation
Lightly ionizing particles
First limit for charge PRL 120 211804 (2018)
as low as e/1000
Low energy spectra from 14.9 kg-yr of low-
background open physics running (DS1-6a)
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 8
New Result: Double Beta Decay to Excited States
Forthcoming arXiv preprint
An inherently multi-site signal topology:
A “source” detector will have a broad energy
spectrum from ββ
The “gamma” detector will measure energy
peaked at the γ energies
41.9 kg y of isotopic exposure
(20.6 kg y of which was blinded)
The most stringent limits to date for ββ to each excited
state of 76Se due to:
Operating an array in vacuum: high detection efficiency
See Poster 254: New results from Majorana
Demonstrator’s search for Double-Beta Decay Exquisite energy resolution for identifying peaks
of 76Ge to Excited States of 76Se (I. Guinn) Low environmental backgrounds & analysis cuts
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 9
GERDA at Laboratori Nazionali del Gran Sasso in Italy
GERDA Collaboration meeting
Zurich, Switzerland
June 2019
http://www.mpi-hd.mpg.de/gerda/ INR
Moscow
ITEP
Moscow
European Commission Kurchatov
Joint Research Centre Institute
JRC Geel
About 100 scientists
from Europe
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 10Background-free experiment design
[Eur. Phys. J. C (2018) 78:388]
• signal topology
Pure water
Liquid Ar
!! decay signal:
single-site event
energy deposition HH
in a 1 mm3 volume PMT
Optical
fibers
# #
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 11Background-free experiment design
[Eur. Phys. J. C (2018) 78:388]
• background mitigation
Pure water
Liquid Ar
!! decay signal:
single-site event
energy deposition HH
in a 1 mm3 volume PMT
Muon veto based on
Optical
fibers Cherenkov light and
plastic scintillator
\
# #
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 12Background-free experiment design
[Eur. Phys. J. C (2018) 78:388]
• background mitigation
Pure water
Liquid Ar
]
!! decay signal:
single-site event
energy deposition HH LAr veto based on Ar
in a 1 mm3 volume PMT scintillation light read
by fibers and PMT
Muon veto based on
Optical
fibers Cherenkov light and
plastic scintillator
\
# #
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 13Background-free experiment design
[Eur. Phys. J. C (2018) 78:388]
• background mitigation
Pure water
Liquid Ar
]
Ge detector
!! decay signal: anti-coincidence
single-site event
energy deposition ] HH LAr veto based on Ar
in a 1 mm3 volume PMT scintillation light read
by fibers and PMT
Muon veto based on
Optical
fibers Cherenkov light and
plastic scintillator
\
# #
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 14Background-free experiment design
[Eur. Phys. J. C (2018) 78:388]
• background mitigation
Pulse shape
Pure water discrimination (PSD)
Liquid Ar for multi-site and
] surface ^, ! events
Ge detector
!! decay signal: anti-coincidence
single-site event
energy deposition ] HH LAr veto based on Ar
in a 1 mm3 volume PMT scintillation light read
H by fibers and PMT
]
_
Muon veto based on
Optical
fibers Cherenkov light and
plastic scintillator
\
# #
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 15The phase II Ge detector array
LAr veto optical fibers Coaxial detector
Low-mass holders
Strings assembly
Low-mass contacts BEGe detector ~0.7 kg
• Up to 41 enriched detectors deployed from Dec. 2015 to Dec. 2019
• Three detectors type (Coaxial, BEGe and IC)
• Two data taking periods with an upgrade in May 2018 in between
• Total enriched detectors mass: 35.6 kg/44.2 kg Inverted Coaxial det. ~1.8 kg
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 16Final phase II data collection summary
GERDA Phase II runs Exposure Physics data Calibration data Special calibration data
Exposure (kg×yr)
Exposure gain (kg×yr / d)
0.10 100
0.08 80
0.06 60
0.04 40
GERDA 20-06
0.02 20
0.00 0
2016-01 2016-07 2016-12 2017-07 2017-12 2018-07 2018-12 2019-07
Date (year-month)
• data collection split in pre/post upgrade periods
o pre-upgrade: data released at Neutrino2018 [Science 365, 6460 (2019)]
o cumulated exposure 58.9 kg e yr
Coax
BEGe
28.6
31.5
• upgrade: new LAr veto system + new IC detector string TAUP2019
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 17Final phase II data collection summary
GERDA Phase II runs Exposure Physics data Calibration data Special calibration data
Exposure (kg×yr)
Exposure gain (kg×yr / d)
0.10 100
0.08 80
0.06 60
0.04 40
GERDA 20-06
0.02 20
0.00 0
2016-01 2016-07 2016-12 2017-07 2017-12 2018-07 2018-12 2019-07
Date (year-month)
• data collection split in pre/post upgrade periods
o pre-upgrade: data released at Neutrino2018 [Science 365, 6460 (2019)]
o cumulated exposure 58.9 kg e yr
• upgrade: new LAr veto system + new IC detector string TAUP2019
IC
8.5
• this talk: Coax
41.8
o final exposure: MN hi e Oj (original design: 100 kg e yr) BEGe
53.3
o full data collection analysed
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 1876Ge detector calibration
• weekly calibrations with 228Th sources
• every 20 s test pulse injection for gain
stability measurement
FWHM (keV)
4 GERDA 18-06
Qb b
FWHM resolution @ PHH (keV) 3.5
QØØ
period BEGe* Coax** IC 3
pre-upgrade =. k ± N. <Phase II physics data modeling before cuts
counts / 5 keV
104 Enriched detectors - 60.2 kg×yr single-detector events
Qbb ± 25 keV
GERDA 19-07
40 42
K K
3
10
2nbb 214
102 Bi 208
Tl 210
214
Bi Po
10
1
10-1
10-2 [JHEP 2020, 139 (2020)]
counts / 5 keV
103
coincidence events
102
10
1
-1
10
10-2
1000 2000 3000 4000 5000
energy [keV]
Published data collection: from Dec. 2015 to April 2018
Blinding strategy: Keep events falling in mnn ± 25 keV blinded
Data quality cuts + muon veto applied
Energy range above 39Ar spectrum (mn = 565 keV)
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 20103
cou
GERD
40 60 210
2nbb 42
Phase II physics data modeling before cuts
K K Co Po
102
10
counts / 5 keV
104 Enriched detectors - 60.2 kg×yr single-detector events
1 Qbb ± 25 keV
GERDA 19-07
212 208 214 228
Data Model Bi + Tl Bi + 214Pb Ac
103 2nbb 40
K 42
K 60
Co 210
Po
10-1
102
10-2
counts / 5 keV
10
103
102
1
10
10-11
10-1 [JHEP 2020, 139 (2020)]
10--22
10
counts / 5 keV
1000 2000 3000 4000 5000
103 energy [keV]
102
MaGe
10 (Geant4) modelling
K. Von Sturm poster
of GERDA
1
Modeling of
10-1 GERDA Phase II data
10-2
1000 2000 3000 4000 5000
Fine modelling of all individual parts: energy [keV]
Priors: Constraints from screening
measurements
Weakness: Fairly high spatial degeneracy
of some components (K, 214Bi)
Main outcome: no full energy peak or other structures close to mnn
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 21Phase II pulse shape discrimination
Analysis of the charge collection time profile informs about event type (bulk single/multi-site, surface events)
BEGe and IC detectors: p/q Coaxial detectors: ANN + risetime
0#!! decay signal efficiency:
• ~ÇÉ:;
aÄÅ = ([[. > ± )%
• ~ÖÜáà
aÄÅ = (?[. k ±Phase II liquid argon veto performances
P. Krause poster
Counts / 5 keV
5000 All detectors - 103.7 kg×yr
GERDA 20-06
Prior liquid argon (LAr) veto The LAr instrumentation
After LAr veto of GERDA and LEGEND-200
Monte Carlo 2n bb - T from [EPJC 75 (2015) 416]
4000 1/2
Counts / 1 keV
42
K
40
2000 K
-
3000 b
EC
1000
40 42
Ar Ca
0 1460 1480 1500 1520 1540
2000
Energy (keV)
1000
600 800 1000 1200 1400 1600
Energy (keV)
• Stable operations over 4 years of data taking
• 0#!! decay signal efficiency: ~åVj = (k>. k ± N. M)%
• Crucial role in background suppression after PSD: ÷ ? in the ROI
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 23Phase II physics spectra after all analysis cuts
• [600 - 1900] keV – Almost pure ?[JJ decays sample
• [1450 - 1530] keV – Strong suppression of 40K and 42K gamma lines (LAr veto + MSE)
• [1900 - 2620] keV – Strong suppression of 214Bi and 228Th gamma lines + Compton
• > 3500 keV – Suppression of almost all a events (p+ contact)
• Extremely powerful complementarity between LAr veto and PSD cuts!
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 24Zoom around the region of interest
Dec. 2019
Dec. 2015
• Bkg index (BI) analysis window: [1930-2190] keV with the exclusion of 208Tl SEP and 214Bi FEP lines and mnn ± 25 keV
• Prior to analysis cuts, BI = 143ëí
%ê × 10
%G cts⁄(keV e kg e yr)
÷Phase II energy spectrum after unblinding! Dec. 2019 Dec. 2015 • Two new counts entering the mnn ± 25 keV blinding window since the last data release • But still no count within PHH ± =ö … 01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 26
Statistical analysis and interpretation
Frequentist analysis*: Bayesian analysis with uniform prior*:
• Median sensitivity for limit setting: • Median sensitivity for limit setting:
O. ] × OP?A Qj (kP% Ö. å. ) 1.4 × 10,F yr (90% C. I. )
• Best fit → no signal -.
• )*/, > 1.4 × 10,F yr 90% C. I.
• 90% C. L. lower limit:
ZP[
O/? > O. ] × OP
?A
Qj L. Shtembari poster
Statistical methods for the new
*Statistical treatment found in [Nature 544, 47–52 (2017)] data release of GERDA
+ includes 23.5 kgeyr phase I exposure
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 27Moving forward
76
Ge (88% enr.)
1030
long-term
LEGEND 1029
M ton
1000 XNY
M/= > MN
=[ yr
1028
T1/2 3s DS [years]
LEGEND mid-term
27
200 10
=NN kg
XNY
M/= > MN
=> yr
1026 IO mmin
bb
range
GERDA Background free
MAJORANA 0.1 counts/FWHM-t-y
running/ended
1025
1.0 count/FWHM-t-y MN
=? yr
1024 -3
10-2 10-1
3
10 1 10 102 10
Exposure [ton-years]
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 28LEGEND: A worldwide joint effort
LEGEND Collaboration meeting, Seattle, Washington, US December 2019
LEGEND mission:
“The collaboration aims to
develop a phased, 76Ge
based double-beta decay
experimental program with
discovery potential at a
half-life beyond 1028 years,
using existing resources as
appropriate to expedite
physics results.”
Large Enriched Germanium Experiment for Neutrinoless JJ Decay
Univ. New Mexico University of South Carolina University Tennessee Oak Ridge National Laboratory
L'Aquila University and INFN Tennessee Tech University Lancaster University Padova University
Lab. Naz. Gran Sasso Jagiellonian University University Liverpool Padova INFN
University Texas, Austin University of Dortmund University College London Czech Technical University Prague
Tsinghua University Technical University Dresden Los Alamos National Lab. North Carolina State University
Lawrence Berkeley Natl. Lab. Joint Inst. Nucl. Res. INFN Milano Bicocca South Dakota School Mines Tech.
University California, Berkeley Duke University Milano University and Milano INFN University Washington
Leibniz Inst. Crystal Growth Triangle Univ. Nuclear. Lab. Institute Nuclear Research Russ. Acad. Sci. Academia Sinica
Comenius University Joint Research Centre, Geel National Research Center Kurchatov Inst. University Tübingen
University of North Carolina Max Planck Institute for Lab. Exper. Nucl. Phy. MEPhI University South Dakota
University of Warwick Nuclear Physics, Heidelberg Max Planck Institute for Physics, Munich University of Zurich
Sichuan University Queens University Technical University Munich Roma Tre University and INFN
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 29LEGEND-200 ongoing LNGS program
String preparation at LNGS First calibration spectra in March 2020 l Ongoing since Feb 2020
using GERDA infrastructure
l GERDA detectors
+ 4 L200 ICPC
+ 5 MJD PPC detectors
operating in liquid argon
l First tests of new DAQ,
calibration system
under real conditions
l First spectra taken using
new head electronics
l Data taking still ongoing
while LNGS activities
are impacted by COVID
LEGEND-200 background Goal
Ge Internal U, Th Chains
Detector Mounts
Front Ends & Mounts
Atmospheric Ar
Ge Cosmogenics • Background contributions near Qββ after all cuts
Cables
Surface a
Cosmic Rays
(NB: design exposure = 1 t e yr)
Nylon Shrouds Total
Optical Fibers • Monte Carlo + data-driven projections of
Ge U/Th, 42K, α based on GERDA, MJD data
Preamplifiers
GERDA
42
K b-decays
68
Ge
60
Co • All others: Monte Carlo + assay-based projections
a-emitters
µ-induced (3400 mwe) • Grey bands indicate uncertainties in assays and
ALL BACKGROUNDS
10
-8
10-7
-6
10
-5
10 10-4 10
-3
background rejection
[counts/(keV kg y)]
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 30LEGEND-1000: Toward a ton-scale experiment
2018 2019 2020 2021 2022 2023
GERDA (100 kg yr) Possible locations:
MAJORANA (75 kg yr) • SNOLab (Canada)
LEGEND-200 Purchase Isotope • CJPL (China)
Fabricate Detectors
• SURF (USA)
Develop/Install New Lock,
• LNGS (Italy)
Experimental Apparatus
Integration/Commissioning
LEGEND-200 Data Runs, Goal: 1 t yr (~5-7 years)
Ton-Scale Down-Select Process
LEGEND-1000 Design/Build, ~6yrs, 2021-2027
Earliest, and optimistic, LEGEND-1000 Data Start 2025/6
LEGEND-1000 background Goal
Ge Internal U, Th Chains
Underground Ar
Reductions for LEGEND-1000:
• U/Th: optimized array spacing, minimize opaque
Detector Mounts
Ge Cosmogenics
Front-Ends & Mounts Surface a
Cables Cosmic Rays materials, larger detectors, better light
collection, cleaner materials
Total
Optical Fibers
Preamplifiers
• 42Ar: strong suppression by using udg. sourced Ar
GERDA
42
K b-decays
68
Ge
60
Co • μ-induced: improved shielding, SNOLab depth
a-emitters
assumed
µ-induced (6000 mwe)
ALL BACKGROUNDS
-8 -6 -5 -3
• Surface α's: assumes achieved UL for BEGes and
10-7 10-4
ICPCs in GERDA
10 10 10 10
[counts/(keV kg y)]
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 31Summary
• MAJORANA: doubled exposure (50 kg e yr) to be released this year
most stringent limits on !! decay to 76Se excited states at this conference
• GERDA data taking completed in Dec. 2019 – 104 kg e yr collected
no signal observed @ mnn – new lower limit on 76Ge 0#!! decay half-life:
XNY
M/= > M. [ × MN=?
Oj @ 90% C. L.
76
Ge (88% enr.)
1030
• LEGEND-200 already using
GERDA infrastructure at LNGS
o Test of prototype electronics and 1029
DAQ started in existing cryostat,
o to be followed by 1028
infrastructure upgrade.
T1/2 3s DS [years]
o Data-taking will begin in 2021
1027
• LEGEND-1000: ton-scale
experiment achievable with 1026 IO mmin
bb
range
modest evolution of Background free
LEGEND-200 design
0.1 counts/FWHM-t-y
25
10 1.0 count/FWHM-t-y
o goal to reach the 10,ê yr 10 counts/FWHM-t-y
discovery potential sensitivity
1024 -3
10-2 10-1
3
10 1 10 102 10
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decayExposure [ton-years] 32List of MAJORANA DEMONSTRATOR related posters
Go to:
https://nusoft.fnal.gov/nova/nu2020postersession/
Search for: “Majorana Demonstrator”
in “All Sessions”
You’ll find up to 3 posters!
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-254.pdf
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-257.pdf
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-586.pdf
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 33List of GERDA related posters
Go to:
https://nusoft.fnal.gov/nova/nu2020postersession/
Search for: “GERDA” & ”in Ge” in “All Sessions”
You’ll find up to 5 posters!
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-342.pdf
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-365pdf
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-464.pdf
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-506.pdf
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-329.pdf
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 34List of LEGEND related posters
Go to:
https://nusoft.fnal.gov/nova/nu2020postersession/
Search for: “LEGEND” in “All Sessions”
You’ll find up to 8 posters!
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-80.pdf
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-113.pdf
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-365.pdf
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-284.pdf
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-392.pdf
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-311.pdf
https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-483.pdf
01 July https://nusoft.fnal.gov/nova/nu2020postersession/pdf/posterPDF-341.pdf
2020 Neutrino2020 conference - 76Ge 0vbb decay 35The end
Upper limit on ünn within 3# flavor model
=
NY =
†HH
M/XNY ñ NY
M/= = £p ß ®
†=©
• Lower 90% C. L. limit: XNY
M/= > M. [ × MN
=?
Oj
• Converted into upper limit on: †HH < [N − M[= ¢;S
• Other inputs:
o £p = M. =>
o 76Ge NME ∈ [=. ?? − ?. Nñ] min NME from Coraggio et al. 2020
max NME from Song et al. 2017
m b b (eV)
m b b (eV)
m b b (eV)
GERDA 20-06
normal ordering
1 1 1
inverted ordering
GERDA 2020
10-1 10-1 10-1
b decay kinematics
Cosmology (extd.)
Cosmology (min.)
10-2 10-2 10-2
10-3 10-3 10-3
-3
10 10-2 10-1 1 10-1 1 10-2 10-1 1
m light (eV) S (eV) m b (eV)
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 3776Ge 0#!! decay search history
0⌫ lower limit
103 T1/2
Heidelberg
G ERDA
background index 1026
Moscow
background index (cts/(keV·kg·yr))
102 ITEP/ KKDC
IePY Claim 1025
M AJORANA
0⌫ lower limit (yr)
101 UCSB/LBL
IGEX
1024
100
St. Gotthard 1023
10 1
T1/2
Milano
2 1022
10
10 3 1021
10 4 1020
1965 1970 1975 1981 1986 1992 1997 2003 2008 2014 2019
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 38Underground laboratories worldwide
see J. Heise talk
GERDA
LEGEND-200
MAJORANA
[arXiv:1801.00587]
• Underground = passive background suppression for « free »
• Isotopic activation suppression (neutron capture – e.g. CDGe + ¨ → CC|Ge → CCAs + 2.7 MeV)
• Large experimental infrastructure required (shielding, cryostat, instrumentation)
• Size/depth/access compromise taken into account by the collaborations
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 39Phase II: From concept to design
plastic scintillator panels LAr veto low-mass, low-
instrumentation activity electronics
muon veto
clean room
wavelength
shifting fibers with
SiPM read-out
Ge detector
array
64 m3 LAr
cryostat
coolant, shielding
low mass
detector holder
590 m3
ultra-pure water
BEGe detector
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 40Phase II physics data modeling before cuts
counts / 5 keV
104 Enriched detectors - 60.2 kg×yr single detector events
Qbb ± 25 keV
GERDA 19-07
212 208 214 228
Data Model Bi + Tl Bi + 214Pb Ac
3
10 2nbb 40
K 42
K 60
Co 210
Po
102
10
1
10-1
10-2 [JHEP 2020, 139 (2020)]
counts / 5 keV
103
102
10 10
counts / 2 keV
counts / 2 keV
GERDA 19-09
GERDA 19-09
M1-enrBEGe - 32.1 kg yr M1-enrCoax - 28.1 kg yr
10
1
-1
10 1 1
10-2
1000 2000 3000 4000 5000
energy [keV]
10-1 10-1
10-2 10-2
1950 2000 2050 2100 2150 1950 2000 2050 2100 2150
energy [keV] energy [keV]
Main outcome: no full energy peak or other structures close to mnn
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 41GERDA overall exposure summary 01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 42
Calibration stability
• small contact detectors: May 2018 upgrade
Shift at 2.6 MeV Peak (keV)
Shift at 2.6 MeV Peak (keV)
GERDA 20-06
GERDA 20-06
BEGe detectors IC detectors
2 2
1 1
0 0
-1 -1
-2 -2
2016-01 2016-07 2016-12 2017-07 2017-12 2018-07 2018-12 2019-07 2016-01 2016-07 2016-12 2017-07 2017-12 2018-07 2018-12 2019-07
Date (year-month) Date (year-month)
• coaxial detectors:
Shift at 2.6 MeV Peak (keV)
GERDA 20-06
Coaxial detectors
2
Check for the 2.6 MeV gamma line
1
shift from 228Th calibration source in
0
each consecutive valid period of time
-1
-2
2016-01 2016-07 2016-12 2017-07 2017-12 2018-07 2018-12 2019-07
Date (year-month)
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 43Liquid argon veto stability
• NYHH decay signal acceptance:
Acceptance (%) May 2018 upgrade
GERDA 20-06
98.5
98.0
97.5
97.0
2016-01 2016-07 2016-12 2017-07 2017-12 2018-07 2018-12 2019-07
Date (year-month)PSD efficiencies stability
• small contact detectors: May 2018 upgrade
Survival fraction
Survival fraction
1.2 1.2
BEGe detectors - PSD cut stability IC detectors - PSD cut stability
GERDA 20-06
GERDA 20-06
208 208
Tl DEP 1593 keV Compton Q ± 35 keV 212
Bi FEP 1621 keV Tl DEP 1593 keV Compton Q ± 35 keV 212
Bi FEP 1621 keV
bb bb
1 1
0.8 0.8
0.6 0.6
0.4 0.4
0.2 0.2
2016-01 2016-07 2016-12 2017-07 2017-12 2018-07 2018-12 2019-07 2020-01 2016-01 2016-07 2016-12 2017-07 2017-12 2018-07 2018-12 2019-07 2020-01
Date (year-month) Date (year-month)
• coaxial detectors:
Survival fraction
1.2
Coaxial detectors - PSD cut stability
GERDA 20-06
208
Tl DEP 1593 keV Compton Q ± 35 keV 212
Bi FEP 1621 keV
bb
1
0.8
PSD time stability checked
by looking at gamma lines
survival fraction from
0.6
0.4
individual calibration runs
0.2
2016-01 2016-07 2016-12 2017-07 2017-12 2018-07 2018-12 2019-07 2020-01
Date (year-month)
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 45Time evolution of Alpha background
• Coax detectors _ background (energy > 3500 keV) before cuts: May 2018 upgrade
corr. rate (cts/day/det)
GERDA 2020-06
enrCoax - PhaseII enrCoax - PhaseII+
-ln(2) t -ln(2) t
1 f(t) = C + N exp f(t) = C + N exp
T1/2 T1/2
C = (131 ± 11)E-3 cts/day/det C = (95 ± 17)E-3 cts/day/det
N = (1033 ± 52)E-3 cts/day/det N = (362 ± 47)E-3 cts/day/det
T1/2 = (138.4 ± 0.2) days T1/2 = (138.4 ± 0.2) days
0.5
0
Jul 16 Dec 16 Jul 17 Dec 17 Jul 18 Dec 18 Jul 19
date (month year)
• BEGe detectors _ background (energy > 3500 keV) before cuts:
corr. rate (cts/day/det)
GERDA 2020-06
enrBEGe - PhaseII enrBEGe - PhaseII+
-ln(2) t -ln(2) t
f(t) = C + N exp f(t) = C + N exp
T 1/2 T 1/2
0.1 C = (39.8 ± 2.2)E-3 cts/day/det C = (36.7 ± 3.6)E-3 cts/day/det
N = (53.3 ± 7.5)E-3 cts/day/det N = (23.3 ± 8.3)E-3 cts/day/det
T 1/2 = (138.4 ± 0.2) days T 1/2 = (138.4 ± 0.2) days
0.05
0
Jul 16 Dec 16 Jul 17 Dec 17 Jul 18 Dec 18 Jul 19
date (month year)
Main outcome: No critical recontamination of BEGe small-contact detector during the upgrade
Detector handling procedure OK for LEGEND-200
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 46Pulse Shape Discrimination #1
BEGe detector: Ø (511 keV) ] (208Tl DEP)
Ø MSE SSE
rss≠
rÆs≠ Ø (511 keV)
] _
H
• MSE cut: Low A/E cut set to
accept 90% of 208Tl DEP from cal.
• Alpha cut: High A/E cut set to
+3∞ of SSE A/E band
No high energy alpha (E>3.5 MeV) survive
SSE • ~ÇÉ:;
Alpha aÄÅ = ([[. > ± )%
MSE PSD uncertainties are systematics dominated
T. Comellato poster
Modelling the collective motion
of charge carrier in Ge detectors
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 47Pulse Shape Discrimination #2
MSE
• MSE cut: Artificial Neural Network
fed with SSE and MSE proxies from cal.
(208Tl DEP and 212Bi FEP)
cut set @ 90% acc. of 208Tl DEP events
±≤≥≥ = (82.3 ± 3.1)%
• Alpha cut: Charge collection risetime
[10%-90%]. Cut optimized from =YHH
and _ samples:
cut set @ max[±,.nn e 1 − ±¥ ]
±µ∂ = (85.5 ± 1.0)%
Alpha
• ~ÖÜáà
aÄÅ = (?[. k ±The Best of MAJORANA & GERDA
MAJORANA GERDA
• Radiopurity of nearby parts • LAr veto
(FETs, cables, Cu mounts, etc.) Both • Low-A shield, no Pb
• Low noise electronics • Clean fabrication
techniques
improves PSD • Control of surface GERDA achieved the lowest
• Low energy threshold (helps exposure background index:
reject cosmogenic • Development of large 5 × 10%G cts⁄(keV e kg e yr)
background) point-contact detectors
• Lowest background and LEGEND-200 needs only x3-5
best resolution 0nbb better.
MAJORANA achieved best energy experiments
resolution: 2.5 keV FWHM at Qbb
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 49Ge Detectors for LEGEND-200
GERDA BEGes and MAJORANA PPCs BEGe
ü Excellent energy resolution
ü Superb pulse-shape sensitivity to reject multi-site
and surface background events
PPC
• But relatively small: = 0.66 and 0.85 kg,
respectively
New Inverted-Coaxial Point Contact detectors
ü First design proposed in 2011
[R. Cooper et al., NIM A665, 25 (2011)]
ü Large active mass up to 3 kg
ü Excellent resolution and pulse shape discrimination ICPC
performance [A. Domula et al., NIM A891, 106 (2018)]
ü Lower surface to volume ratio
ü Reduced background due to lower number of
channels per mass of 76Ge
ü Production started early 2019
About 60 detectors expected by fall 2021
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 50PEN — self-vetoing structural material
• PEN — Poly(ethylene 2,6-naphthalate)
- Scintillates, providing veto to potential backgrounds
- Light yield ~1/3 of conventional plastic scintillators BEGe
- Particle identification using pulse shape discrimination (PSD)
possible
- Functions as a wavelength shifter of LAr scintillation photons
(128 nm)
PPC
- Transparent in the visible range
- Mechanically stronger than silicon, stronger than Cu at
cryogenic temps.
• Production of LEGEND-200 low-background detector
holder plates
- Possible replacement of Si detector holder plates
- Plates produced via CNC machining using clean procedures
ICPC
- PEN holders deployed in LEGEND “post GERDA test” at LNGS
• R&D Activities
- Enhanced cleanliness,
- Dedicated test stands and simulations to further study optical
properties:
- WLS, Light yield, attenuation, surface effects
- Injection molded components (encapsulation of objects) Design
01 July 2020 Neutrino2020 conference - 76Ge 0vbb decay 51You can also read
