the experimental search for direct dark matterotranto/2015/slides/galbiati/galbiati_otranto.pdf ·...
TRANSCRIPT
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The Experimental Search for Direct Dark Matter
Cristiano Galbiati Princeton University Scuola di Otranto
June 6, 2015
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Has gravitational interactions
Is long lived
Is cold
Is not baryonic
Feng
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Dark Matter• Best evidence for new physics beyond Standard Model
• Unambiguous evidence
• Possibly connected with electroweak symmetry breaking, SUSY, and structure formation
• Very bright prospects for experimental observation
• Astroparticle physics: direct and indirect searches
• Particle physics: CMS and ATLAS at LHC
• Cosmology: halo profiles, CMB, BBN
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e,γχ,n
Attisha
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1 10 100 1000 10410!5010!4910!4810!4710!4610!4510!4410!4310!4210!4110!4010!39
10!1410!1310!1210!1110!1010!910!810!710!610!510!410!3
WIMP Mass !GeV"c2#
WIMP!nucleoncrosssection!cm2 #
WIMP!nucleoncrosssection!pb#
(Green&ovals)&Asymmetric&DM&&(Violet&oval)&Magne7c&DM&(Blue&oval)&Extra&dimensions&&(Red&circle)&SUSY&MSSM&&&&&&MSSM:&Pure&Higgsino&&&&&&&MSSM:&A&funnel&&&&&&MSSM:&BinoEstop&coannihila7on&&&&&&MSSM:&BinoEsquark&coannihila7on&&
8BNeutrinos
Atmospheric and DSNB Neutrinos
CDMS II Ge (2009)
Xenon100 (2012)
CRESST
CoGeNT(2012)
CDMS Si(2013)
EDELWEISS (2011)
DAMA SIMPLE (2012)
ZEPLIN-III (2012)COUPP (2012)
SuperCDMS Soudan Low ThresholdXENON 10 S2 (2013)
CDMS-II Ge Low Threshold (2011)
SuperCDMS Soudan
Xenon1T
LZ
LUX (2013)
DarkSide G2
DarkSide 50
DEAP3600
PICO250-CF3I
PICO250-C3F8
SNOLAB
SuperCDMS
7BeNeutrinos
NEUTRINO C OHER ENT SCATTERING
NEUTRINO COHERENT SCATTERING
CDMSlite
(2013)
SuperCDMS SNOLAB
Z-mediated scattering
H-mediated scattering
Figueroa-Feliciano
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(1)
(2)
(3)
R. Kolb and M. TurnerNon-baryonic Not hot
Not short lived
(1) Equilibrium
(2) Eq. Cooling
(3) Freeze-out
��� f̄f
��� f̄f
�� � f̄f
dn�
dt+ 3Hn� = �⇥�Av⇤
⇤(n�)2 �
�neq
�
⇥2⌅
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The WIMP MiracleDark matter “leftovers” inversely proportional
to annihilation cross section
��h2 =m�n�
�c=
3 � 10�27 cm3/s⇥⇥Av⇤freezout
⇥�Av⇤freezout = 3 � 10�26 cm3/s
⇥⇥Av⇤ � �2 (100 GeV)�2 � 10�25 cm3/s
Cosmology alone tells us to look at the weak scale!
For weak scale particles:
Feng
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The 1985 Papers
• Drukier and Stodolski, Phys Rev D 30, 2295 (1985)
• Goodman and Witten, Phys Rev D 31, 3059 (1985)
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WIMP Scattering: Coherence
Halo particle of mass m (100 GeV) velocity v=300 km/s
on nucleus of mass M (100 GeV)
λ = h/(2mv) ≈ 1 fm RA = 1.0 x A1/3 fm
K = (2mv)2/2M ≈ 100 keV
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WIMP Coherent Scattering
�0 = ��,nA2 µ2A
µ2n
µA =MAM�
MA + M�
µn =mnM�
mn + M�
q =�
(2MAE)
F (q) =3j1(qrn)
qrne�q2s2/2
�(q) = �0F2(q)
Reduced Mass WIMP-Nuclide:
Reduced Mass WIMP-Nucleon:
Momentum transferred:
Form Factor:
For zero momentum transfer:
Non-null momentum transfer:
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Dark Matter Signatures
0.2
0.4
0.6
0.8
1
200 100806040 200 100806040 200 100806040
1x10-2
1x10-3
1x10-4
1x10-5
1x10-1
10.5
0.05
0.01
0.005
0.1
Recoil Energy E [keV]R
Form Factor (Square of) Integral Rate over ThresholdDifferential Rate
Ev/kg/keV/d
Ev/kg/d
ArAr
ArGe
GeGe
XeXe Xe
(a) (b) (c)
Rate per unit mass depends on atomic number A Nuclear recoils spectrum depends on atomic number A
Yearly modulation of spectrum Daily modulation of nuclear recoil directionality
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WIMP Wind & Signatures
WIMP “wind”
in the summer, moving against wind
in the winter, moving away from wind
expect an annual modulation in signal!
Drukier-Freese-Spergel
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Status of Experimental Exploration• One unconfirmed result from DAMA
• strong statistical significance, 8σ
• Standard WIMP elastic scattering ruled out by Ar, Ge, and Xe
• Two powerful techniques lined up long range searches in the standard WIMP scenario
• Ge, Xe, and Ar
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DAMA Singles Spectrum: Peak at 3±1 keV
Intensity 1 cpd/kg
2-6 keV
Time (day)
Res
idua
ls (c
pd/k
g/ke
V) DAMA/NaI (0.29 ton yr)
(target mass = 87.3 kg)DAMA/LIBRA (0.53 ton yr)
(target mass = 232.8 kg)
0
2
4
6
8
10
2 4 6 8 10 Energy (keV)
Rat
e (c
pd/k
g/ke
V)
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2-6 keV
Time (day)
Res
idua
ls (c
pd/k
g/ke
V) DAMA/NaI (0.29 ton yr)
(target mass = 87.3 kg)DAMA/LIBRA (0.53 ton yr)
(target mass = 232.8 kg)
Energy (keV)
S m (c
pd/k
g/ke
V)
-0.05
-0.025
0
0.025
0.05
0 2 4 6 8 10 12 14 16 18 20
DAMA Oscillated Spectrum: Peak at 3±1 keV, Intensity 0.05 cpd/kg
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0
5
10
15
20
25
30
35
40
45
0 1000 2000 3000 4000
TD channel
Counts/bin
DAMA Concidence Spectrum:
Peak at 3±1 keV Intensity 10,000 cpd!!! Origin: 3.2 keV X-rays from 40Ar, produced by
decay of 40K (13 ppb of natK)
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1 10 100 1000 10410!5010!4910!4810!4710!4610!4510!4410!4310!4210!4110!4010!39
10!1410!1310!1210!1110!1010!910!810!710!610!510!410!3
WIMP Mass !GeV"c2#
WIMP!nucleoncrosssection!cm2 #
WIMP!nucleoncrosssection!pb#
(Green&ovals)&Asymmetric&DM&&(Violet&oval)&Magne7c&DM&(Blue&oval)&Extra&dimensions&&(Red&circle)&SUSY&MSSM&&&&&&MSSM:&Pure&Higgsino&&&&&&&MSSM:&A&funnel&&&&&&MSSM:&BinoEstop&coannihila7on&&&&&&MSSM:&BinoEsquark&coannihila7on&&
8BNeutrinos
Atmospheric and DSNB Neutrinos
CDMS II Ge (2009)
Xenon100 (2012)
CRESST
CoGeNT(2012)
CDMS Si(2013)
EDELWEISS (2011)
DAMA SIMPLE (2012)
ZEPLIN-III (2012)COUPP (2012)
SuperCDMS Soudan Low ThresholdXENON 10 S2 (2013)
CDMS-II Ge Low Threshold (2011)
SuperCDMS Soudan
Xenon1T
LZ
LUX (2013)
DarkSide G2
DarkSide 50
DEAP3600
PICO250-CF3I
PICO250-C3F8
SNOLAB
SuperCDMS
7BeNeutrinos
NEUTRINO C OHER ENT SCATTERING
NEUTRINO COHERENT SCATTERING
CDMSlite
(2013)
SuperCDMS SNOLAB
Figueroa-Feliciano
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0 10 20 30 40 501
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
log 10
(S2 b/S
1) x
,y,z
cor
rect
ed
S1 x,y,z corrected (phe)
3 6 9 12 15 18 21 24 27 30 keVnr
1.3
1.8
3.5
4.65.9
7.1
keVee
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S1 [PE]100 150 200 250 300 350 400 450
90f
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0
5000
10000
15000
20000
25000
30000
35000
50% 65% 80% 90%
1,422 kg×day - zero background - S1 only
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S1 [PE]
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
1Ar Residuals Box
39Dark Matter Search - S2 and Radial Cut - 0.1
0
500
1000
1500
2000
2500
3000
3500
4000
4500
50%65%
80% 90%
Ar Residuals Box39
Dark Matter Search - S2 and Radial Cut - 0.1 same data with S2 and radial cut
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]2 [GeV/cχM1 10 210 310 410
]2 [cm
σ
50−10
49−10
48−10
47−10
46−10
45−10
44−10
43−10
42−10
41−10
40−10
DS-50 (2014)
WARP (2007)
LUX (2013)
XENON-100 (2
012)
CDMS (2010)
PandaX-I (20
14)
Neutrino Limit
third best dark matter limit at high masses
LHC@14 TeV
1 eventfrom neutrino-induced
nuclear recoil
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DarkSide A Scalable Zero-Background Program• Pulse shape of scintillation provides powerful discrimination for NR
vs. EM events Rejection factor ~107 at 36 keVr threshold
• Ionization:scintillation ratio a semi-independent discrimination mechanismGreat spatial resolution from ionization drift localizes events, allowing rejection of multiple interactions, "wall events", etc.
• Underground argon39Ar abatement factor ≥150
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Multi-Stage Program at LNGS
DarkSide-10Prototype detector
Future multi-ton detector
DarkSide-50 First physics detector
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Discrimination
Beta/Gamma Nuclear Recoil
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Liquid Argon TPC & Cryostat
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4-m Diameter Liquid Scintillator
Neutron Veto
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10-m high 11-m Diameter
Water Tank
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DarkSide-50
Liquid Argon TPC
Liquid scintillator neutron veto
Water Cherenkov muon veto
Radon-suppressed assembly clean room
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Two-Phase Argon TPC
PMTs
Liquid Argon Target
Field cage
Gaseous Argon layer
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7Li(p,n) on thin LiF target to generate low
energy, pulsed, monochromatic neutron beam
Triple coincidence between pulse proton beam, LAr TPC, liquid scintillator detectors
for detection of scattered neutrons
SCENE
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SCENE
Recoil Energy [keV]10 20 30 40 50 60
Kr(0V/cm)
83m
S1 Relative to
0.14
0.16
0.18
0.2
0.22
0.24
0.26
0.28
0.3
0.32
0 V/cm
100 V/cm
200 V/cm
300 V/cm
1000 V/cm
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SCENE
Recoil energy [keV]10 20 30 40 50 60
S2 yield [PE/keV]
2
4
6
8
10
12
14
1650 V/cm
100 V/cm
200 V/cm
300 V/cm
500 V/cm
/keV]
-S2 yield [e
1
2
3
4
5
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SCENE
Drift electric field [V/cm]0 200 400 600 800 1000
S1 yield relative to 0 field
0.7
0.75
0.8
0.85
0.9
0.95
1
1.05
1.1
1.15 57.2 keV
dεParallel to
dεPerpendicular to
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Class 100 Clean Room Radon < 5mBq/m3
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S1 [PE]0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
s]
× kg
×Events/[50 PE
7−10
6−10
5−10
4−10
3−10
2−10
1−10AAr (200 V/cm, 44 kg)
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S1 [PE]0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
s]
× kg
×Events/[50 PE
7−10
6−10
5−10
4−10
3−10
2−10
1−10AAr (200 V/cm, 44 kg)
UAr (200 V/cm, 44 kg)
AAr (200 V/cm, 44 kg)
UAr (200 V/cm, 44 kg)
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S1 [PE]
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
s]
× kg
×Events/[50 PE
7−10
6−10
5−10
4−10
3−10
2−10
1−10AAr (200 V/cm, 44 kg)
UAr (200 V/cm, 44 kg)
UAr (200 V/cm, 4 kg core)
AAr (200 V/cm, 44 kg)
UAr (200 V/cm, 44 kg)
UAr (200 V/cm, 4 kg core)
AAr (200 V/cm, 44 kg)
UAr (200 V/cm, 44 kg)
UAr (200 V/cm, 4 kg core)
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DarkSide-50• Third best dark matter limit with AAr exposure of 1,422 kg×day
• Only liquid noble dark matter experiment background-free
• Rejection better than 1÷1.6×107 (compare 1÷200 for Xe)
• Detector in final configuration
• Underground argon isotopic depletion better than 300
• TMB problem fixed, veto at design 99.5% neutron rejection
• UAr science run started - additional exposure of 847 kg×day collected
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What goal for the large scale exploration of dark matter?
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]2 [GeV/cχM1 10 210 310 410
]2 [cm
σ
50−10
49−10
48−10
47−10
46−10
45−10
44−10
43−10
42−10
41−10
40−10
DS-50 (2014)
WARP (2007)
LUX (2013)
XENON-100 (2
012)
CDMS (2010)
PandaX-I (20
14)
Neutrino Limit
third best dark matter limit at high masses
LHC@14 TeV
1 eventfrom neutrino-induced
nuclear recoil
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Experiment σ [cm2]@1 TeV/c2
σ [cm2]@10 TeV/c2
LUX[10k kg×day Xe]
1.1×10-44 1.2×10-43
XENON[7.6k kg×day Xe]
1.9×10-44 1.9×10-43
DS-50[1.4k kg×day Ar]
2.3×10-43 2.1×10-42
ArDM[1.5 tonne×yr Ar]
8×10-45 7×10-44
DEAP-3600[3.0 tonne×yr Ar]
5×10-46 5×10-45
XENON-1ton [2][2.7 tonne×yr Xe]
3×10-46 3×10-45
LZ [1][15 tonne×yr Xe]
5×10-47 5×10-46
DS-20k[100 tonne×yr]
9×10-48 9×10-47
1 Neutrino Event[400 tonne×yr Ar or 300 tonne×yr Xe]
2×10-48 2×10-47
ARGO[1,000 tonne×yr]
9×10-49 9×10-48
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What are the backgrounds for large scale, high mass dark
matter searches?
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Elastic scatters of pp solar neutrinos
Radioactive noble gases (39Ar)
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Elastic Scatters of pp Solar Neutrinos on Electrons
• 200 events/tonne×yr in 30-200 keVnr ROI for argon means 80,000 background events @neutrino floor
• No problem due to β/γ rejection better than 1÷1.6×107
• 20 events/tonne×yr in 0-10 keVee ROI for xenon means 6,000 background events @neutrino floor
• Irreducible background due to rejection limited to 1÷200
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39Ar Rejection1,422 kg×day (@AAr)
1 tonne×yr (UAr)
1,000 tonne×yr (UAr/DAr)
already achieved
stronger discrimination present value stat limited
additional active isotopic depletion
x 300 (39Ar AAr/39Ar UAr)
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Based on what we know today, can a depleted argon experiment be background
free at the scale of 400 tonnes×yr?
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Yes• pp neutrino-electron scattering
Not a concern thanks to pulse shape discrimination
• 214Pb from 222Rn and 85KrNot a concern thanks to pulse shape discrimination
• 39ArDiscrimination proven so far on exposure of 1 tonne×yr UAr equivalentNo deviations from statistical behavior of discrimination Current 1÷1.6×107 rejection limited by statistics SiPM should allow to increase light yield by ×1.5, which projects to more than 3 additional orders of magnitude in discrimination at the same threshold Further isotopic depletion of 39Ar available if required
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Based on what we know today, can a xenon experiment be background free at the scale of 300 tonnes×yr?
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No• [3] Next generation XENON-1t experiment need to contain their electron-recoil background
to below 30 μDRU for a 99.75% rejection to obtain 0.7 events in 2.7 tonne×yr exposure(1 DRU = 1 count / [keVee × kg × day])
• Is a 99.75% rejection reasonable?XENON-100 [2]: 2 leakage events over 400 in ROILUX [5]: 1 leakage events over 160 in ROI
• [3] pp neutrino-electron scattering: Irreducible background, 12 μDRU ≈ 0.3 (event/tonne×yr) • [3] 214Pb from 222Rn: 1mBq Rn ≈ 9 μDRU ≈ 0.2 (event/tonne×yr)
• Is 1 mBq of 222Rn reasonable? XENON-100: ≤ 1.2 mBq [2], ≃ 4 mBq [3] in 62 kg target for 222Rn chain; LUX [4]: 4-20 mBq in 350 kg target for 222Rn chain, 3 mBq for 220Rn chain222Rn background to scale with surface and recirculation flowBorexino’s success in 222Rn isolation, often invoked as a proof of principle for feasibility of Xe TPC goal, is taken out of context: Borexino’s 222Rn contamination during fluid operations: hundreds of mBq
• [3] 85Kr: 0.2 ppt ≈ 8 μDRU ≈ 0.2 (event/tonne×yr)
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DarkSide-20k
• Background-free exposure of 100 tonne×yr
• Sensitivity 9×10-48 cm2 @1 TeV/cm2 A factor 5 better than LZ
• 30 tonne (20 tonne fiducial) detector
• MC indicates UAr self-vetoing sufficient (LS veto not required)
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DarkSide-20k Characteristics• 15 m2 of SiPM’s
Demonstrated from 15 to 50% LY increase per unit area over PMT’s Demonstrated dark count under control Demonstrated noise control and good performance for 10 cm2 SiPM’s tile at 87 K Tile size required for DS-20k is 25 cm2 factor 2 above what already achieved FBK custom design, first custom production May 2015Mass production possibly at L-Foundry
• Low-background titanium from Russia for cryostat
• 50 kV drift fieldAlready achieved in DarkSide-10 and DarkSide-50 mockup
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DarkSide Depleted Argon Sources• Urania
• expansion of Colorado UAr extraction facility to reach 100 kg/day
• Aria
• Giant cryogenic distillation column in Seruci, Sardinia
• Gas purification AND active isotopic depletion exploiting finite vapor pressure difference 39Ar/40Ar
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What is Required?
• Upgrade of argon extraction at Cortez: 100 kg/day
• Distillation of Argon in Seruci, Sardinia, for further abatement of 39Ar
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C.Kendziora 2.19.2015
Man
350 meters
325 meters Eiffel Tower
Seruci Distilation Column
Size ComparisonThe proposal is to construct a 350 meter talldistillation column at a mine called Suruci inSardina Italy to separate Argon 39 fromArgon 40.
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DarkSide Depleted Argon Verification
• ~1 kg argon detector in a shallow underground location at Seruci for initial assessment39Ar sensitivity: 1 mBq/kg Factor 103 depletion (2-3 times better than DS-50)
• ArDM for high-sensitivity tests of tonne-scale batches 39Ar sensitivity: 10 μBq/kg Factor 105 depletion
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Argo• Background-free exposure of 1,000 tonne×yr
• Sensitivity 9×10-49 cm2 @1 TeV/cm2Covers space throughout neutrino floor
• Permits precision measurements of solar neutrinos TPC affords very sharp definition of fiducial volume Argon ten times brighter than organic liquid scintillatorStatistical precision 2% for 7Be, 10% for pep, and 15% for CNO neutrinos Systematics under studyCosmogenics under control
• 300 tonne detectorRequires Borexino-style shield for solar neutrinos study
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20- 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
DS-20k
ARGO
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7Li(p,n) on thin LiF target to generate low
energy, pulsed, monochromatic neutron beam
Triple coincidence between pulse proton beam, LAr TPC, liquid scintillator detectors
for detection of scattered neutrons
SCENE
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SCENE
Recoil Energy [keV]10 20 30 40 50 60
Kr(0V/cm)
83m
S1 Relative to
0.14
0.16
0.18
0.2
0.22
0.24
0.26
0.28
0.3
0.32
0 V/cm
100 V/cm
200 V/cm
300 V/cm
1000 V/cm
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SCENE
Recoil energy [keV]10 20 30 40 50 60
S2 yield [PE/keV]
2
4
6
8
10
12
14
1650 V/cm
100 V/cm
200 V/cm
300 V/cm
500 V/cm
/keV]
-S2 yield [e
1
2
3
4
5
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SCENE
Drift electric field [V/cm]0 200 400 600 800 1000
S1 yield relative to 0 field
0.7
0.75
0.8
0.85
0.9
0.95
1
1.05
1.1
1.15 57.2 keV
dεParallel to
dεPerpendicular to
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Directional Dark Matter Test @Napoli• Participating groups: Naples, Roma 1, APC-IN2P3, Princeton, Temple, UCLA
• Coordinator: Giuliana Fiorillo (Napoli)
• Refurbishment of Tandem accelerator to create dedicated proton line for experiment under way
• Permanent array of liquid scintillator neutron coincidence counters planned
• Start of operations with LAr TPC in October 2015
• Will provide facility available for calibration of other detectors with monochromatic, pulsed neutron beam
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Very Low Threshold DM Searches• Gaseous argon detectors have reached record thresholds below 100 eV
• I. Giomataris et al., “A novel large-volume spherical detector with proportional amplification read-out”, Journal of Instrumentation 3, P09007 (2008).
• Availability of depleted argon made available by the Urania and Aria programs may enable construction of ultra-low background gaseous argon detectors
• Suitable to explore dark matter interactions on electrons
• Suitable to monitor supernovae explosions via the detection of neutrino-induced coherent scattering of argon nuclides
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Conclusions• DS-20k most ambitious program proposed, goes more than ×5 beyond LZ
• Argo to cover entire parameter space through neutrino floor and to enable precision measurements of solar neutrinos significantly beyond Borexino capability
• Letter of Intent submitted to LNGS April 27 2015
• Background-free requirement key element continued excellence in dark matter exploration DS-20k and Argo have sound and credible strategy to keep background-free through their stated goals Unique physics capabilityReal competitor for large-scale background-free exploration of dark matter is single-phase argon (both approaches, TPC and single-phase argon, require UAr/DAr)INFN leading strategy procurement of depleted argon with Urania and Aria
• Exploration of possible directional signal continues with dedicated experiment at Naples Unique possibility of conjugating directionality with zero background strategy