[email protected]26 Emilija Pantic for the DarkSide collaboration UC DAVIS 1 DARKSIDE:CHALLENGES, PERSPECTIVES AND PLANS http://darkside.lngs.infn.it/collaboration 3rd Berkeley Workshop on the Direct Detection of Dark Matter - DarkSide-50 brief intro and status - DarkSide-20k CPP Look for references here
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DARKSIDE:CHALLENGES, PERSPECTIVES AND PLANS · 39Ar in atmospheric Ar 39Ar in underground Ar 1000 mBq/kg 0.73± 0.11 mBq/kg With respect to Atmospheric Ar: ! ... FBK NUV-HD-LF-HRq
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Tag radiogenic n Tag radiogenic 𝛾 Tag cosmogenic n 𝜇
WCV
LSV
𝜋n
prompt
delayed
Water WCV
LSV
radi
opur
e
The veto system of the DarkSide-50 experiment, JINST 11, no.03, P03016 (2016)
>99.1% efficiency to veto radiogenic neutrons via delayed capture on 10B and 1H (AmBe + MC)
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S1 [PE]0 1000 2000 3000 4000 5000 6000
s]
× kg
×Events / [50 PE
8−10
7−10
6−10
5−10
4−10
3−10
2−10
1−10(LSV Anti-coinc.)AAr Data at 200 V/cm
(LSV Anti-coinc.)UAr Data at 200 V/cm
Kr (Global Fit)85
Ar (Global Fit)39
4
Intrinsic background of Underground Argon
39Ar in atmospheric Ar
39Ar in underground Ar
1000 mBq/kg
0.73± 0.11 mBq/kg
With respect to Atmospheric Ar: !> factor of 300 reduction of intrinsic radioactivity in UAr!
~ factor of 1400 reduction of 39Ar activity
Background in ROI = ~50% β-events + ~50% of 𝛾-events Results from the first use of low radioactivity argon in a dark matter search, Phys.Rev. D93, no.8, 08110 (2016)
Multidim.!spectral fit of MC (g4ds) on
AAr/UAr!plus delayed coincidence
tagging
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Dark Matter search data for 70d UAr
Results from the first use of low radioactivity argon in a dark matter search, Phys.Rev. D93, no.8, 08110 (2016)
S1 [PE]50 100 150 200 250 300 350 400 450
90
f
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0
50
100
150
200
250
50%90% 99%
WIMP Search Region
]nr
Energy [keV20 40 60 80 100 120 140 160 180 200
NR acceptance contours from AmBe in
DS50 + SCENENo events in the
WIMP search region.
Reject:!abnormal clustering of S1 signal!prompt/delayed signal in LSV !preceding 𝜇-like event in vetoes!top and bottom of TPC in drift
AAr!!
UAr
Select !Single scatters!Use Hinkley f90 model!Fit to AAr data Scale to UAr data!Derive 0.01 ER leakage ev. / S1 bin
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Latest DarkSide-50 Dark Matter search result
Results from the first use of low radioactivity argon in a dark matter search, Phys.Rev. D93, no.8, 08110 (2016)!PLOT adapted from Results from a search for dark matter in the complete LUX exposure arXiv:1608.07648 (2016)
101 102 103 104 105
WIMP Mass [GeV/c2]
10�2
10�1
100
101
102
103
WIM
P–nu
cleo
ncr
oss
sect
ion
[zb]
PandaX–II 2016XENON100 2016Dark
Side–50 2015
LUX WS2013
LUX WS2014–16
LUX WS2013+WS2014–16
8B
10�46
10�45
10�44
10�43
10�42
WIM
P–nu
cleo
ncr
oss
sect
ion
[cm
2 ]
0.007 t yr0.01 t yr
LUX WS2
013
DarkSide-50 !
3yr projectio
n
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DarkSide-50 Short Term PlanNew data almost one full year: !-test and utilize blind analysis in steps !-re-optimize full analysis chain!-implement improved background model for ERs !-finalize background model for “Cherenkov plus ER” events
*CALIS - a CALibration Insertion System for the DarkSide-50 dark matter search experiment - Paper submitted!**Effect of Low Electric Fields on Alpha Scintillation Light Yield in Liquid Argon - Paper submitted
Other studies/publications: !-G4DS simulation framework!-G4DS recombination model !-ER background spectrum!-f90 model!-alpha background!-alpha yield**!-combined energy scale!-detector performance!-CALIS*!-S2/S1!-Effective field theory
S1 [PE]38000 40000 42000 44000 46000
10
20
30 0 V/cm
S1 [PE]38000 40000 42000 44000 46000
2
4
6 50 V/cm
S1 [PE]38000 40000 42000 44000 46000
Counts
5
10
15 100 V/cm
S1 [PE]38000 40000 42000 44000 46000
5
10 150 V/cm
S1 [PE]38000 40000 42000 44000 46000
200
400
600
800200 V/cm
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DarkSide-20k challenges and status
15m11m
10m
16m
8m4m
2.9m0.35m
@LNGS @LNGS
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How to collect 50 000 kg of underground argon!
and then purify and distill to arrive to 30 000 kg by 2020 ?
Each purification or distillation step introduces a loss.
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URANIA and ARIA
Aria !Seruci1 - purification of UAr !
Seruci2- isotopic separation of Ar-39 !Rate @150kg/d !
Depletion factor goals:!~10 for Ar-39 and >1000 for N2,02,Kr per
pass
Urania !UAr extraction/
purification@100kg/d !Ar extraction expected to
start in 2017.Extraction&purification!@upgraded Colorado
facility
Des
tilla
tion
via
350m
tall
colu
mn
@ S
eruc
i min
e
Urania in cooperation with Kinder Morgan !ARIA in cooperation with Regione Sardegna (production of other isotopes of interest for medical application)
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How to provide 14 m2 of single-photon sensitive and radiopure
surface with < 10 000 number of readout channels?
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DarkSide-20k Photodetector module
SiPM development by FBK/TIFPA. TIA=Trans-Impedance Amplifier. SNR=Signal to Noise Ratio
8cpd/100t is approx.100𝜇Bq/100t; Borexino Rn level < 0.57cpd/100t!Solar neutrino detection in a large volume double-phase liquid argon experiment, JCAP 08 (2016
Toy MC study for 300t (100t fiducial) LAr TPC@LNGS.!
400tyr exposure
CNO LZCNO HZ
PEP HZ/LZ
7Be HZ/LZ
Energy [MeV]1−10×6 1 2 3 4
yr]
× 400 tonne
×Events / [10 keV
1
10
210
310MC Data
AllνBe-7
νCNO-
νpep-νB-8
P32
Radon
Other Cosmogenics
Energy [MeV]1−10×6 1 2 3 4
yr]
× 400 tonne
×Events / [10 keV
1
10
210
310MC Data
AllνBe-7
νCNO-
νpep-νB-8
P32
Radon
Other Cosmogenics
directly measure CNO 𝜈s! !
improve precision on !7Be/pep 𝜈s!
!discriminate between two solar metallically models
Unc
erta
inty
[%]
“Conservative” scenario: 222Rn @100𝜇Bq/100t
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25]2 [GeV/cχ M
10 210 310 410
]2 [cm
σ
-5010
-4910
-4810
-4710
-4610
-4510
-4410
-4310
-4210
-4110
DarkSide-50
(2015)
DarkSide-50
(3 yr proj.)
Coherent neutrino-nucleus scattering floor
WARP (2007)
PandaX-II (2
016)XENON1
00 (2012)
LUX (2016)
CDMS(2015)
PICO (2015)
DarkSide-20k
(100 t yr p
roj.)
DarkSide-20k
(200 t yr p
roj.)
Argo (1000 t
yr proj.)-induced N
Rν1
plotted discovery limit for LXe detector
0.007 t yr0.1 t yr
100 t yr
precision measurements on low energy solar 𝜈s!extend dark matter sensitivity for higher masses via bck. subtraction!
*explore 1D Directionality via columnar recombination
LZ/XeNT
1000 t yr
Argo = concept for 300 t LAr TPC
*R&D efforts ongoing; see ReD experiment@Naples and Measurement of scintill.and ionization yield and scintill. pulse shape from NRs in LAr Phys. Rev. D 91, (2015)
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300 t LAr TPC conceived to reach 1000 t yr exposure for precision measurement of solar neutrinos and expanded reach of DM search
Measured 39Ar level in UAr to be factor 1400 smaller than in AAr.Efficiency of the Neutron Veto via delayed capture is >99.1%.More data for new DM search and investigation of rare backgrounds. (Cherenkov events in coincidence with ER event) D
arkS
ide-
50
Critical R&D facilities: URANIA, ARIA and prototype development are already underway.A SiPM based, large-area photo-detection module @ LAr temperature has been demonstrated Feasible to explore DM up to neutrino floor for MDM>100GeV in background-free mode thanks to PSD against 𝜈 induced ERs and intrinsic/dissolved radioactive nuclei inducing ERs.
Dar
kSid
e-20
kAR
GO
collaboration:
Summary
Work supported by NSF, INFN, DOE, NCN and others. LNGS and FNAL lab support.