anais-112 · anais goal m. martinez. f. araid & u. zaragoza susy2018 –barcelona, july 23-27...
TRANSCRIPT
ANAIS-112: A test of DAMA/LIBRA dark matter
signal at the Canfranc Underground Laboratory
María Martínezon behalf of the ANAIS team SUSY2018 – Barcelona, July 23-27 2018
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• Intro• ANAIS-112• Detector response• Background model• ANAIS sensitivity• Summary
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 2018
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Intro: DARK MATTER ANNUAL MODULATION
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 2018
Annual modulation: DAMA/LIBRA signal
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 20184
DAMA/LIBRA @ LNGS Rate modulation consistent with DM requirements:
We expect a modulated rate
with 1 year period
11.9s CL (2.17 ton × yr)
• Ultra-pure NaI(Tl)
• 25 × 9.7 kg
• More than 20 cycles
(combined with
100kg DAMA) Since 2010 (phase2)threshold @ 1 keV
arXiv:1805.10486
ANAIS goal
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 20185
ANAIS (Annual modulation with NAI Scintillators) intends
to confirm the DAMA/LIBRA modulation signal
using the same target and technique
in a different environment at the Canfranc Underground Laboratory (Spain)
ANAISExperimental requirements:
• Energy threshold at or below 1-2 keVee
• Background as low as possible below
10 keVee (at or below a few cpd/keV/kg)
• Very stable operation conditions
The ANAIS program
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 20186
ANAIS-112• Commissioning in March-April 2017
• Calibration and general assessment
from April to July 2017
• Dark matter run is underway since
3rd, August 2017: first year of data
taking is about to be successfully
completed
ANAIS-112: Detectors
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 20188
Detector Quality powder Received at LSC:
D0, D1 <90 ppb K December 2012
D2 WIMPScint-II March 2015
D3 WIMPScint-III March 2016
D4, D5 WIMPScint-III November 2016
D6, D7, D8 WIMPScint-III March 2017
•9 NaI(Tl) crystals grown from selected
ultrapure NaI powder (Alpha Spectra Inc)
• Housed in OFE copper
•Two Hamamatsu R12669SEL2 PMT
•coupled to each crystal at LSC clean
room
•low background
•high QE (∼40%)
Housing made at LSC of
electroformed copper
ANAIS-112: Shielding
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 20189
16 plastic scintillatorsAnti-Rn box
Neutron shielding
ANAIS-112: Low energy calibration
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201810
Detectors equipped with a Mylar window!
Radon-free system for low energy calibration:
• 109Cd sources on flexible wires (radon-free)
• Energies: 11.9, 22.6 and 88.0 keV
• Simultaneous calibration of the nine modules
• Performed every two weeks
ANAIS-112: Data acquisition system
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201811
• Individual PMT signals digitized and
fully processed
• Trigger at phe level for each PMT
signal
• AND coincidence in 200 ns window
• Redundant energy conversion by QDC
• rigger in OR mode among modules
• Electronics at air-conditioned-room to
decouple from temperature
fluctuations
Muon detection system
• tag muon related event
• monitor onsite muon flux
ANAIS-112: Slow control
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201812
– Monitoring:
Rn content, humidity, pressure, different temperatures, N2 flux, PMT HV, muon rate, …
Data saved every few minutes and alarm messages implemented
– Stability checks:
gain, trigger rate, …
• Monitoring environmental parameters since the start of DM run
Detector Response: duty cycle & stability
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201814
• Good total rate stability
• Excellent duty cycle
316.07 days until 4th July 2018
Electric Power Failure @ LSC
Liquid nitrogen supply shortcuts
Total trigger rate (9 detectors)
Total rate with >1 peak at each PMTs
Detector response: gain stability
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201815
• Good gain stability
→ monitoring / correcting
possible gain drifts
Evolution of 109Cd lines from calibrations along the whole data-taking (∼ 1 year)
Detector response: light collection
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201816
- all modules
- at different set-ups
- checked to be stable over time
M.A. Oliván et al, Astropart. Phys. 93 (2017) 86
Larger and more homogeneous than the reported light collection for DAMA/LIBRA detectors:
Phase 1: 5.5-7.5 phe/keV
Phase 2: 6-10 phe/keV
• Outstanding light collection of ~15 phe/keV
Detector respose: threshold
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201817
- Multiparametric cuts to properly select events
with pulse shapes from NaI(Tl) scintillation
(efficiency computed on 109Cd calibration and 22Na and 40K coincidence populations)
• Energy threshold limited by PMT noise filtering protocols efficiency
bulk 22Na and 40K events identified by
coincidences with high energy gammas
Improved algorithm for peak identification,
detecting ∼ 75% of the phe1 keVee
• Effectively triggering below 1 keVee
Detector response: noise rejection
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201818
Temporal parameters of the pulse region of 78% acceptance
from 22Na and 40K populations
• Effective filtering protocols for PMT noise limitig the energy threshold
63, 78, 86%
1.- Biparametric cut to properly select events with pulse shapes from NaI(Tl) scintillation
P1=0.08
Detector response: noise rejection
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201819
Still working on final tuning,
before unblinding the low energy data.
Expected analysis down to 1 keVee
- Acceptance efficiency curves after two cuts:
A blank module will be set-
up to monitor non NaI(Tl)
scintillation events along the
second year of operation
PRELIMINARY
1.-Asymmetric events (<2 keVee): accept events with number_of_peaks > 4 @ every PMT
• Effective filtering protocols for PMT noise limitig the energy threshold
Detector response: noise rejection
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201820
• Effective filtering protocols for PMT noise limitig the energy threshold
Background model: bkg sources
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201822
• Activity from external components measured with HPGe detectors at Canfranc
• Internal activity directly assessed: mainly 40K, 210Pb
J. Amaré et al, Eur. Phys. J. C 76 (2016) 429
40K: by identifyingcoincidences
C. Cuesta et al., Int. J. Mod. Phys. A. 29 (2014) 1443010
232Th, 238U: determined
by alpha rate following
PSA and analysis of BiPo
sequences at a level of a
few mBq/kg, but 210Pb out
of equilibrium0 150 300 450 600 750 900 1050 12000.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
D7
D8
D6
D4
D5
AS2K#3
D3
Alp
ha
Sp
ecific
Activity (
mB
q/k
g)
Days (since 12th March 2015)
D2
• Geant4 Monte Carlo simulation
• accurate quantification of background sources
• Detailed background models for each detector
Background model: bkg sources
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201823
• Activity from external components measured with HPGe detectors at Canfranc
• Internal activity directly assessed: mainly 40K, 210Pb
• Cosmogenic activity: short-lived Te and I isotopes, 3H, 22Na, 109Cd, 113Sn
22Na: from analysis of coincidences
Same order of activity measured using HPGe by
SABRE on AstroGrade powder: 0.8 mB/kg = 69 kg-1d-1
SABRE Colaboration, arXiv:1806.09344v1
109Cd, 113Sn: from peaks at bindingenergies of K-shell electrons (after EC)
Preliminary estimate of production rates:109Cd (2.38±0.20) kg-1d-1
113Sn (4.53±0.40) kg-1d-1
3H: additional background source contributing only in
the very low energy region required, which could be
tritium
D0-D1: 0.20 mBq/kg
D2-D8: 0.09 mBq/kg (upper limit DAMA/LIBRA)
Same order of 3H activity fitted by COSINE-100
P. Adhikari et al, Eur. Phys. J. C (2018) 78:490
JCAP 02 (2015) 046
Astropart. Phys.97 (2018) 96
Int. J. Mod. Phys. A 33 (2018) 1843006
• Geant4 Monte Carlo simulation
• accurate quantification of background sources
• Detailed background models for each detector
Backgrond model : comparison with data
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201824
Comparison for high energy (>250 keV) (3 August 2017 to 30 March 2018)
Individual contributions:
Backgrond model : comparison with data
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201825
Comparison for low energy (<100 keV) (3 August 2017 to 30 March 2018)
Comparison for very low energy (<20 keV) (Commissioning run, June-July 2017)
Most significant contributions:
• 40K and 22Na peaks
• 210Pb (bulk+surface)
• 3H
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ANNUAL MODULATION SENSITIVITY
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 2018
Detection limit at 90% C.L. for a critical limit at 90% C.L. for ANAIS-112
• Conservative estimate of background from measured, efficiency corrected levels
• 2-6 keVee region
• 5 years
Annual Modulation sensitiviy
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201827
I. Coarasa et al, arXiv:1704.06861v1
90% probability of detecting an
annual modulation signal at 90% C.L.
Dark matter hypothesis
ANAIS-112 can detect the annual modulation
in the 3s region compatible with the
DAMA/LIBRA result.
Better prospects if good acceptance
efficiency is achieved at 1 keVee
DAMA region: JCAP04(2009)10
Detection limit at 90% C.L. for a critical limit at 90% C.L. for ANAIS-112
• Conservative estimate of background from measured, efficiency corrected levels
• 2-6 keVee region
• 5 years
Annual Modulation sensitiviy
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201828
ANAIS-112 has a detection limit for annual modulation lower than the
measured amplitude by DAMA/LIBRA: 0.0103 ± 0.0008 cpd/kg/keVee
Detection Limit for annual modulation amplitude: for ANAIS-112 parameters
Factor of Merit: from the variance of the estimator of the modulated amplitude
Model-independent annual modulation
Summary and outlook
M. Martinez. F. ARAID & U. Zaragoza SUSY2018 – Barcelona, July 23-27 201829
ANAIS-112: data taking using 112.5 kg running smoothly
• Very high duty cycle
• Careful low energy calibration (from external gamma sources and bulk emissions)
• Excellent light collection of ~15 phe/keV and triggering at 1 keVee in all modules
• Robust filtering of PMT events (dominating below 10 keVee)
• Monitoring of environmental parameters and muons
• Good background understanding, dominated by crystal activity (210Pb, 40K, 22Na, 3H)
Next future…• Preliminary blind analysis for annual modulation will be carried out once completed the
first year of data in August, 2018
• Data taking will continue in the same conditions for at least another year, together with ablank module to monitor non NaI(Tl) scintillation events
• Measurement of scintillation Quenching Factor for nuclear recoils scheduled at TUNL laboratories (Duke University, US), investigating possible dependence on crystal quality
• Combining data between COSINE-100 and ANAIS-112 agreed
• Plan to make ANAIS data public after use to allow independent analysis
The ANAIS-112 running at Canfranc with good prospects to test the
DAMA/LIBRA modulation signal using same target and technique