Post on 15-Jul-2020
transcript
pantic@ucdavis.edu 26
Emilija Pantic for the DarkSide collaboration
UC DAVIS
1
D A R K S I D E : C H A L L E N G E S , !P E R S P E C T I V E S A N D P L A N S
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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Pulse shape discrimination of ERsS2/S1 discrimination of ERs
DarkSide-50 LAr dual phase TPCLight Charge+
1
Edrift200V/cm
Eextr
e-e-
e-e-e-
e-
S2
S1
46kg of LAr!38 3” PMTs!TPB as wavelength shifter!cathode/anode = ITO on fused silica!Teflon as reflector !extraction grid
3D positioning O (few mm)
S1 [PE]100 150 200 250 300 350 400 450
90
f
0
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1
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5000
10000
15000
20000
25000
30000
35000
50% 65%80% 90%
Nuclear Recoils
Electronic Recoils
ER Rejection power >107
First Results from the DarkSide-50 Dark Matter Experiment at LNGS, Phys.Lett. B 743
83mKr S1 Light Yield:!7.0 ± 0.3 PE/keV @ 200 V/cm
f90
f90 = fraction of S1 in the first 90ns
S1 [PE]
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prompt
WCV
LSV
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DarkSide-50 Veto Detectors:
Neutrons that scatter in the TPC can be detected via capture signal on 10B or thermalization signal in LSV.
30t Liquid Scintillator Veto (LSV) = TMB + PPO + PC!1000t Water Cherenkov Veto (WCV)
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
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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
Power <250mW
Sapphire substrate
FEB !with Cryo-TIA, transmitter
at Sapphire PCB!SNR>6!
bandwidth>20MHz
50x50mm2 SiPM tile
FR4 PCB substrate
FEB !with Cryo-TIA,
transmitter at FR4 PCB!SNR>6!
bandwidth>20MHz
20x20mm2 SiPM tile
Power <250mWconceptual sketch
KEY GOALS ACHIEVED IN R&D
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FBK NUV-HD-LF-HRq SiPM technology
publication in preparation
2. high dynamic range !via (25-35 𝜇m) cell size
1. peak efficiency in NUV
5V, NUV-HD LF 25 um cell
OV [V]1 2 3 4 5 6 7 8
]2DCR [Hz / mm
-410
-310
-210
-110
3. low intrinsic electric field
Temperature (K)
Over Voltage (V)
Dar
kCur
rent
Rate
[Hz/
mm
2 ]
T [K]50 100 150 200 250 300
AP Probability
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
OV3 V4 V5 V6 V
4. high value of quenching resistor
Afte
rPul
sing
Pro
babi
lity
Temperature (K)
NUV-HD LF 25 um cell
NUV-HD LF 25 um cell LN2
T [K]50 100 150 200 250 300
DiCT Probability
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
OV3 V4 V5 V6 V5. physical trench isolation
Dire
ct C
ross
-Tal
k Pr
ob.
NUV-HD LF 25 um cell
preliminary
preliminary preliminary
preliminary
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Hybrid scheme for SiPMs summing
TIA
SiPMs
TIA
SiPMs
Parallel Configuration Series/Parallel Configuration
+Vb +Vb Optimization of summed capacitance and signal input to!
Cryogenic Trans-Impedance Amplifier!and differential (optical) transmitter.
Transmitter
Maintain SNR>6 for high threshold efficiency at SPE and photon timing ~10ns for Pulse Shape Discrimination
Amplitude [mV]-20 0 20 40 60 80 100 120 140 160 180
Counts / [0.25 mV]
0
200
400
600
800
1000
1200
1400
= 2.8 mV σ Baseline: mean = 0 mV,
= 3.0 mVσ SPE peak: mean = 17 mV,
SNR: 6.0
!SNR = SPE/𝜎baseline: ~6!
~5V OV; LN2 NUV-HD-LF 5mmx5mm
preliminary
4p4s
publication in preparation
20x20mm2
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Cryogenic system
based on DarkSide-50 cryogenic system
bi-directional LAr line
LAr to heat exchanger and purification
GAr to heat exchanger and purification system!
LN2 powered LAr condenser
LAr to recovery
LAr from heat exchanger, radon trap and purification
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Dual-phase octagonal TPC
ITO on bonded acrylic for electrodes !Cu field cage shrinks with reflector !
200V/cm drift field !Teflon as reflector!
TPB as wavelength shifter !stainless steel (titanium) cryostat
Full size components scaled down (1ton) prototype in 2017. Things in bold differ from DarkSide-50
liquid level control via diving bell!5210 SiPMs-based PDM modules !
Cu motherboard holds 25 PDM !extraction linear grid Active mass !
23 tons
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What is the perspective of DarkSide-20k?
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°z/z
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Relative Light Yield
0.9
0.92
0.94
0.96
0.98
1
1.02
1.04
1.06
1.08
1.1
DarkSide-50 Data
G4DS Simulation
Fit
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DarkSide-20k light yield via G4DS
Light yield for 39Ar with an electric field of 200 V/cm!
~ 9 PE/keV !assuming 40% PDE of PDM
°z/z
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
S1 Light Yield [PE / keV]
0
2
4
6
8
10
12
14
16
0
5
10
15
20
25
30
Normalized vertical coordinate.
Center BottomTop
Ligh
t yie
ld P
E/ke
V]
G4DS = Monte Carlo simulation with detailed geometry, electronics chain, tuned and validated optics
parameters for S1 on various DarkSide-50 data.
See P.Agnes talk “g4ds the DarkSide simulation tool” at UCLA DM 2016
Validation
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Modeling ER and NR response in LAr
See P.Agnes talk “g4ds the DarkSide simulation tool” at UCLA DM 2016
G4DS = also models the recombination probability as a function of recoil energy using DarkSide-50 data inputs from endpoint of 39Ar, 83mKr
summed peak and 37Ar.
validations for ER
tuning for ER Mei Model for NR quenching +
AmBe !validations
for NR
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DarkSide-20k Background budget
ROI= 30-200keVr. Events in ROI have no veto, no fiducial, no PSD cut. 222Rn level in DS50 is <2𝜇Bq/kg
Background / [100t yr]
Events in ROI / [100t yr]Background
Internal β/𝛾39Ar = DS-50!
85Kr, 222Rn = << 1.8 x 108 0.06g4ds PSD sim
Internal NRs <<< <<<e -𝜈pp scatters~200ev/ty 2 x 104 <<<
External NRs <154 <0.12g4ds Veto sim
Cosmogenic NRs𝜈-induced NRs 1.6
Cosmogenic β/𝛾 3 x 105 <<0.01<0.1
surface is active
PTFE/SSg4ds Veto sim
g4ds Veto sim
222Rn = DS50 1 x 105“What if?” <<<
“What with?” Cherenkov + β/𝛾 ongoing analysis, it is rare, pattern!and fiducial cuts are effective
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DarkSide-20k PSD simulation
Cold + Warm !Amplifier
Discriminator TDC HITS Count number of PDMs!arrival time resolution ~10ns
X5210
RC shape ADC Charge Pulse integral!keep dynamic rangebaseline
specifications
S1 [PE]50 100 150 200 250 300 350 400 450
200
f
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1
10
210
310
410
]ee
Energy [keV5 10 15 20 25 30 35 40 45 50
0.001 evts/1 PE leakage
G4DS ERs simulation:!!
S1 light yield = 9PE/keV @200V/cm!
!39Ar as in DS-50!
! f200 = fraction of light in the
first 200ns
high NR acceptance ~90%
100 t yr exposure
~50keVr
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Sensitivity of DarkSide-20k
]2 [GeV/cχ M10 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
Background-free exposure of 100 t yr !reaching 1.2 x10-47cm2 at DM mass of 1TeV/c2!
( with 39-Ar level as in DS-50)
LZ/XeNT
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DarkSide-20k Plans
Number of collaborating institutions is growing.
Proposal is submitted to NSF and INFN.
Full size components scaled down (1ton) TPC prototype including is planned for 2017. Material Screening Strategy is being finalized.
Continue with photodector modules R&D to optimize performance.!Start setting up facilities for mass production and testing.
PDM testing facility @Naples!Capacity: 4 mother boards
Continue with production of ARIA modules and testing. ! ARIA module testing
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Bq / 100 tonne]µRadon Activity [ 10 20 30 40 50 60 70 80 210 210×2
Uncertainty [%]
0
5
10
15
20
25
30CNO (HZ)
pep (HZ)
Be (HZ)7
CNO (LZ)
pep (LZ)
Be (LZ)7
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
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Solar 𝜈 detection in dual-phase LAr TPC
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.