Results on dark matter annual modulation from ANAIS-112 experiment - - PowerPoint PPT Presentation

▶
results on dark matter annual modulation from anais 112
SMART_READER_LITE
LIVE PREVIEW

Results on dark matter annual modulation from ANAIS-112 experiment - - PowerPoint PPT Presentation

Oct 30, 2023 236 likes •654 views

Results on dark matter annual modulation from ANAIS-112 experiment J. Amar, S. Cebrin, D. Cintas, I. Coarasa, E. Garca, M. Martnez, M.A. Olivn, Y. Ortigoza, A. Ortiz de Solrzano, J. Puimedn, A. Salinas, M.L. Sarsa , P . Villar

slide-1
SLIDE 1

Results on dark matter annual modulation from ANAIS-112 experiment

  • J. Amaré, S. Cebrián, D. Cintas, I. Coarasa, E. García,
  • M. Martínez, M.A. Oliván, Y. Ortigoza, A. Ortiz de Solórzano, J. Puimedón,
  • A. Salinas, M.L. Sarsa, P

. Villar UNIVERSIDAD DE ZARAGOZA

11 September 2019

slide-2
SLIDE 2

ANAIS experiment

Annual modulation with NAI Scintillators

  • Confirmation of DAMA-LIBRA modulation signal -> same target and

technique / different experimental approach / different environmental conditions affecting systematics

  • At Canfranc Underground Laboratory, @ SPAIN (under 2450 m.w.e.)

taking data since August 2017

  • 3x3 matrix of 12.5 kg NaI(Tl) cylindrical modules = 112.5 kg of active mass

80 800 m rock

slide-3
SLIDE 3

ANAIS-112 Experimental Strategy

Annual modulation with NAI Scintillators

EXPERIMENTAL GOALS

  • Maximizing exposure (mass x time)
  • Stable operation
  • Data blinding
  • Low energy threshold (1keVee)

Low noise DAQ system / excellent light collection / good energy calibration down to 1keV / efficient PMT noise events filtering

  • Low background @ 1-6 keV

Radiopure detectors / Convenient shielding (including muon veto) / efficient PMT noise events filtering /

slide-4
SLIDE 4

OUTLINE

The ANAIS-112 first year general performance -> Eur. Phys. J. C 79 (2019) 228 The ANAIS-112 background model -> Eur. Phys. J. C 70 (2019) 412 The ANAIS-112 sensitivityprospects -> Eur. Phys. J. C 70 (2019) 233

ANAIS-112 first results-> Phys. Rev. Lett. 123 (2019) 031301

10% first year unblinded (randomly chosen days)

slide-5
SLIDE 5
  • 12.5 kg cylindrical NaI(Tl) detectors built @
  • Alpha Spectra, Co (US)
  • 40K / 210Pb @ NaI(Tl)
  • Optical quality
  • 2 x HQE PMTs Ham12669SEL2 coupled at LSC

clean room

  • Installed at LSC in

a convenient shielding

ANAIS detectors and shielding

slide-6
SLIDE 6

Mylar window for energy calibration

109Cd sources on flexible wires in a Radon free

system which allows the simultaneous calibration of the 9 modules Energies 11.9 keV / 22.6 keV / 88.0 keV Every two weeks

ANAIS-112 calibration system

slide-7
SLIDE 7
  • DAQ hardware and software designed and tested with previous set-ups -> ROBUST
  • Individual PMT signals digitized and fully processed (14 bits / 2GS/s)
  • Trigger at phe level for each PMT
  • Logical AND coincidence in 200ns window for each module triggering
  • Redundant energy conversion (with QDCs for HE)

ANAIS-112 DAQ

slide-8
SLIDE 8
  • DAQ hardware and software designed and tested with previous set-ups -> ROBUST
  • Individual PMT signals digitized and fully processed (14 bits / 2GS/s)
  • Trigger at phe level for each PMT
  • Logical AND coincidence in 200ns window for each module triggering
  • Redundant energy conversion (with QDCs for HE)
  • Electronics at air-conditioned-room to decouple from temperature

fluctuations

ANAIS-112 DAQ

slide-9
SLIDE 9

The ANAIS-112 Dark Matter Run started on August 3, 2017 Accumulated live time in the first year: 341.72 days in the half second year: 185.36 days

___________________________

total:527.08 days ANAIS-112 Duty Cycle 1st year 2nd year (until Feb19)

slide-10
SLIDE 10

The ANAIS-112 Dark Matter Run started on August 3, 2017 Accumulated live time in the first year: 341.72 days in the half second year: 374.30 days

___________________________

total:716.02 days ANAIS-112 Duty Cycle 1st year 2nd year

slide-11
SLIDE 11

ANAIS-112 Low Energy Calibration

Periodic 109Cd calibrations

They allow monitoring (and if necessary correcting) possible gain drifts in the modules. Done every 2 weeks Evolution of the positions of

109Cd lines along ANAIS-112.

All the modules, except D4 and D5, have been very stable during this period of data taking.

88.0 keV 22.6 keV 11.9 keV

PMT HV bias changed

slide-12
SLIDE 12

ANAIS-112 Light Collection

Excellent light collection

Larger and more homogeneousthan the light collectionforDAMA/LIBRA –phase 2 detectors Being continuouslymonitored

M.A. Oliván et al, Astropart. Phys. 93 (2017) 86

DAMA/LIBRA: Phase 1: 5.5-7.5 phe/keV Phase 2: 6-10 phe/keV JINST 7 (2012) 03009

slide-13
SLIDE 13

ANAIS-112 Monitoring of muons

Muon rates onsite are being monitored along the ANAIS-112 DM run. Muon related events are triggering ANAIS DAQ 70 s Total trigger rate Trigger rate after filtering 1 s after a muon veto trigger Most of them are removed by rejecting 1 second after a veto trigger The fraction of live time rejected after the application of this filtering amounts only to a 3%.

slide-14
SLIDE 14

ANAIS-112 Data Analysis

slide-15
SLIDE 15

Calibration at LE combines 109Cd lines with 22Na and 40K (every 1.5 months)

ANAIS-112 HE /LE calibration

Calibration @ HE (above 50 keV) we estimate energy by linearizing the pulse area – QDC relation for each module and calibratingwith backgroundlines(every two weeks) Bulk 22Na and 40K events identifiedby coincidences with highenergy gammas Populationsat very LE well tagged by the coincidence Effectively triggering below 1 keV

0.87 keV from 22Na is actually below our analysis threshold, but clearly above our trigger threshold Selection by the coincidence allows to use these events (almost free from noise/background)

slide-16
SLIDE 16

Calibration at LE combines 109Cd lines with 22Na and 40K (every 1.5 months)

ANAIS-112 HE /LE calibration

Full First Year Data selected by coincidence with a HE gamma Fitted to a Gaussian + linear bckg Allows checking the energy calibration procedure in the RoI

22Na 40K

slide-17
SLIDE 17

ANAIS-112 Event Selection

  • Single Hit events
  • Events arriving more than

1 second after a muon Live Time (after cut) = 511.16 days

slide-18
SLIDE 18
  • Biparametric cut to properly select

events with pulse shapes from NaI(Tl) scintillation PMT noisefilteringprotocols:

ANAIS-112 Event Selection

10 % data unblinded background @ RoI (random distribution)

  • Single Hit events
  • Events arriving more than

1 second after a muon Live Time (after cut) = 511.16 days

Efficiency calculated from 22Na and 40K events

slide-19
SLIDE 19

PMT noisefilteringprotocols:

ANAIS-112 Event Selection

  • Asymmetric events rejection

(E<2keV), number of peaks >4 at each PMT

  • Single Hit events
  • Events arriving more than

1 second after a muon Live Time (after cut) = 511.16 days BKG CAL

Efficiency calculated from calibration events

  • Biparametric cut to properly select

events with pulse shapes from NaI(Tl) scintillation

slide-20
SLIDE 20

ANAIS-112 Event Selection efficiency ANALYSIS THRESHOLD @ 1 keV

slide-21
SLIDE 21

ANAIS-112 Event Selection

10 % data unblinded background @ RoI (random distribution)

Raw data below 10 keV

slide-22
SLIDE 22

ANAIS-112 Event Selection

10 % data unblinded background @ RoI (random distribution)

  • Biparametric cut to properly

select events with pulse shapes from NaI(Tl) scintillation

slide-23
SLIDE 23

ANAIS-112 Event Selection

10 % data unblinded background @ RoI (random distribution)

  • Asymmetric events

rejection (E<2keV), number

  • f peaks >4 at each PMT
slide-24
SLIDE 24

ANAIS-112 Event Selection

10 % data unblinded background @ RoI (random distribution)

  • Events arriving more

than 1 second after a muon

  • Single Hit events

1 keVee

slide-25
SLIDE 25

Detailed background models based on Geant4 Monte Carlo simulation and accurate quantification of background sources

– Internal activity directlyassessed by different techniques: 40K, 210Pb, natural chains – Activity from external components measured with HPGe detectors, mainlythe PMTs – Cosmogenic activity in crystals(22Na, short lifeI and Te isotopes, Tritium, 109Cd,

113Sn, etc.)

ANAIS-112 Background Model

40K and 22Na peaks and 210Pb (bulk+surface) and 3H continua are

the most significant contributions in the very low energy region

JCAP 02 (2015) 046

  • Astropart. Phys. 97 (2018) 96
  • Int. J. Mod. Phys. A 33 (2018) 1843006
slide-26
SLIDE 26

Overall description of measured data at all energy ranges above 2 keV in coincidence and anticoincidence is good HE total spectra

ANAIS-112 Background Model

About 5% average deviation between simulationand measurement

slide-27
SLIDE 27

HE concidence spectra

ANAIS-112 Background Model

Overall description of measured data at all energy ranges above 2 keV in coincidence and anticoincidence is good About 3% average deviationbetween simulationand measurement

slide-28
SLIDE 28

LE anticoincidence spectra For the 10% unblindeddata Overall description of measured data at all energy ranges above 2 keV in coincidence and anticoincidence is good

ANAIS-112 Background Model

About 8% average deviationbetween simulationand measurement @ 2-6 keV

slide-29
SLIDE 29
  • Good agreement at low

energy (<100 keV)

  • At very low energy (<20 keV)

(Commissioning July 2017) Most significantcontributions:

  • 40K and 22Na peaks
  • 210Pb (bulk+surface)
  • 3H

ANAIS-112 Background Model

Below 2 keVthe background model does not explain the measurement in about a 50%.

slide-30
SLIDE 30

arXiv:1903.03973

slide-31
SLIDE 31

ANAIS-112 annual modulation

Backgrounddecayrate in the RoI consistentwith our backgroundmodel (in green) vs constant+ exponentialfit (in red)

slide-32
SLIDE 32

ANAIS-112 annual modulation

M1 events above the RoI (6-20 keV) M2 events in the RoI (1-6 keV)

40K events (2-5 keV) 22Na events (0-2 keV)

Evolution of “control populations” consistentwith the absence of modulation

slide-33
SLIDE 33

Least squared fit of the ANAIS-112 time-binned data in 1-6 / 2-6 keV energy regions to: τ is fixed from background model ω is fixed (1 year period) φ is fixed to have the maximum of the cosine function in June, 2nd Sm is fixed to 0 to analyze the null hypothesis and left unconstrained for the modulation hypothesis DAMA/LIBRA result with 1 –free parameter is shown for comparison

ANAIS-112 annual modulation

slide-34
SLIDE 34

Null hypothesis is well supported by the χ2 test (p-values of 0.67 and 0.18 for 2-6 and 1-6 keV energy regions) Best fits for the modulation hypothesis have p-values slightly lower than for the null hypothesis

2-6 keV -> 1-6 keV -> 𝑇" = −0.0044 ± 0.0058 𝑑𝑞𝑒/𝑙𝑕/𝑙𝑓𝑊 𝑇" = −0.0015 ± 0.0063 𝑑𝑞𝑒/𝑙𝑕/𝑙𝑓𝑊

ANAIS-112 annual modulation

(𝑇"

7898 = 0.0102 ± 0.0008 cpd/kg/keV)

(𝑇"

7898 = 0.0105 ± 0.0011 cpd/kg/keV)

slide-35
SLIDE 35

Least squared fit of the ANAIS-112 time-binned data in 1-6 / 2-6 keV energy regions to: ω is fixed (1 year period) φ is fixed (2nd June)

ANAIS-112 annual modulation

slide-36
SLIDE 36

Null hypothesis is well supported by the χ2 test (p-values of 0.63 and 0.09 for 2-6 and 1-6 keV energy regions) Best fits for the modulation hypothesis have p-values slightly lower than for the null hypothesis

2-6 keV -> 1-6 keV -> 𝑇" = −0.0029 ± 0.0050 𝑑𝑞𝑒/𝑙𝑕/𝑙𝑓𝑊 𝑇" = −0.0036 ± 0.0054 𝑑𝑞𝑒/𝑙𝑕/𝑙𝑓𝑊

ANAIS-112 annual modulation

(𝑇"

7898 = 0.0102 ± 0.0008 cpd/kg/keV)

(𝑇"

7898 = 0.0105 ± 0.0011 cpd/kg/keV)

slide-37
SLIDE 37

Least squared fit of the ANAIS-112 time-binned data in 2-6 keVenergy regions to: ω is fixed (1 year period)

ANAIS-112 annual modulation

slide-38
SLIDE 38

Statistical significance of

  • ur result is determined by

the standard deviation of the modulation amplitude distribution, σ(Sm) We quote our sensitivity to DAMA/LIBRA result as the ratio SmDAMA / σ(Sm) We project our sensitivity with our updated background, efficiency estimates and its errors and live time distribution

ANAIS-112 sensitivity

3σ sensitivitymodel independentis at reach in 4-5 years (total) of data taking

68% uncertainty in SmDAMA

slide-39
SLIDE 39

ANAIS-112 sensitivity

3σ sensitivitymodel independentis at reach in 4-5 years (total) of data taking

1. 75 1.66 2.04 1.94

Present sensitivity: 2σ

68% uncertainty in SmDAMA

Statistical significance of

  • ur result is determined by

the standard deviation of the modulation amplitude distribution, σ(Sm) We quote our sensitivity to DAMA/LIBRA result as the ratio SmDAMA / σ(Sm) We project our sensitivity with our updated background, efficiency estimates and its errors and live time distribution

slide-40
SLIDE 40
  • ANAI-112 is taking data sinceAugust 2017: 112.5 kg of NaI & running smoothly
  • Careful low energy calibration (from external gamma sources and bulk emissions)
  • Excellent light collection of ~15 phe/keV and triggering below 1 keVee in all modules
  • 1 keVee analysis threshold / limited by PMT events rejection procedure
  • Good background understanding but in 1-2 keV energy region
  • 2 years of data blind- analysedfor model independent annual modulation
  • We confirm our sensitivity projections to DAMA/LIBRA result -> 3σ at reach in less than 3y more
  • Null hypothesis is well supported by the χ2 test
  • Best fits are incompatible at 2.6σ with DAMA/LIBRA results, although present sensitivity is 2σ
  • Short term plan:
  • 3 years more of data taking in same conditions
  • Working in analysis improvements & background understanding at 1-2 keV
  • Blank module already installed to check systematics
  • REF for scintillation in ANAIS crystals measured at TUNL facility -> Analysis ongoing
  • ANAIS data will be released after use to allow independent analysis

Summary and Outook