Neutrino Signals at Dark Matter Direct Detection Experiments · 2020. 6. 30. · Franco et al.,...
Transcript of Neutrino Signals at Dark Matter Direct Detection Experiments · 2020. 6. 30. · Franco et al.,...
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Neutrino Signals at Dark Matter Direct Detection Experiments
Jocelyn Monroe, Royal Holloway, University of London
XXIX International Conference on Neutrino Physics and Astrophysics
June 30, 2020
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Dark Matter Direct Detection
γγ
Backgrounds: γ e- ➙ γ e- N ➙ NN ➙ N’ + α, e-
ν N ➙ ν N
experimental requirements: particle ID for recoil N, e-, alpha, n (multiple) final states
Jocelyn Monroe June 30, 2020 / p. 2
Signal: N ➙ N or e- ➙ e-
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ν
Backgrounds: γ e- ➙ γ e- N ➙ NN ➙ N’ + α, e-
N ➙ N?
very similar requirements! (and ideally also measure direction) ν
ν
Dark Matter Direct Neutrino Detection
νSignal: ν N ➙ ν N or ν e- ➙ ν e-
Jocelyn Monroe June 30, 2020 / p. 3
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2008: Neutrino Backgrounds to Dark Matter Searches and Directionality
Jocelyn Monroe May 30, 2008
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2008 2020: Neutrino Backgrounds Signals in Dark Matter Searches (and Directionality)
Jocelyn Monroe May 30, 2008
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ν Cross Sections
Z
N
ν ν
N
O(tens) of events/ton-year = ~ 10-46 cm2 limit
An irreducible background, without direction measurement!
JM, P. Fisher, Phys. Rev. D 76:033007 (2007)
ν-N coherent scattering: ~ A2 x (Eν/MeV)2 x 10-44 cm2 recoils are O(10 keV) … neutrino floor in DM searches
Φ(solar B8 ν) = 5.86 x 106 cm-2 s-1
JM, P
. Fis
her,
Phys
. Rev
. D76
(20
07)
J. Dobson, UCLA DM 2018
LZ Projected Nuclear Recoil Backgrounds
circa 2008
Aprile et al., PhysRevLett 123 (2019)
circa 2019
Jocelyn Monroe June 30, 2020 / p. 3
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ν Cross Sections
Z
e
ν ν
e
ν-N coherent scattering: ~ A2 x (Eν/MeV)2 x 10-44 cm2 recoils are O(10 keV) … neutrino floor in DM searches
J. Dobson, UCLA DM 2018
LZ Projected Nuclear Recoil Backgrounds
ν-e elastic scattering: smaller by ~ (me / Eν) but recoils are “high” energy ~ Eν and directional!
LZ Projected Electronic Recoil Backgrounds
J. Dobson, UCLA DM 2018
Jocelyn Monroe June 30, 2020 / p. 7
J. D
obso
n, U
CLA
DM
’18
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What ν signals can future dark matter detectors see?
https://masterclass.icecube.wisc.edu/en/learn/detecting-neutrinos Jocelyn Monroe June 30, 2020 / p. 8
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What ν signals can future dark matter detectors see?
https://masterclass.icecube.wisc.edu/en/learn/detecting-neutrinos Jocelyn Monroe June 30, 2020 / p. 8
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Future Large-Mass Dark Matter Detectors
https://lz.slac.stanford.edu/our-research/lz-research
Goal: zeptobarn -> yoctobarn sensitivity to dark matter!
Detector Technology: dual-phase Time Projection Chambers with 4-50 tonne liquid Xe, Ar targets
read out primary scintillation: “S1” + proportional gas scintillation from drifted electrons: “S2” • x-y resolution ~cm • z resolution ~mm
Jocelyn Monroe June 30, 2020 / p. 9
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Jocelyn Monroe Jan. 23, 2019
XENON-nT: 6 t LXe (active), following XENON-1T (LNGS), from 2020.
PandaX-4: 4 t LXe (active), following PandaX (JinPing), from 2020.
LZ: 7 t LXe (active), following LUX (SURF), from 2020.
DarkSide-20k: 50 t LAr (LNGS), ArDM+DEAP+DS50+MiniCLEAN, from 2023.
DARWIN: 40 t LXe (LNGS), following XENON-nT.
ARGO: 400 t LAr (SNOLAB?), following DarkSide-20k.
2-Phase TPCs: Near(ish) Future
10
5 cm x 5 cm tiled SiPM
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Gamma ray interactions: electron recoil final states rate ~ Ne x (gamma flux), O(1E7) events/(kg day) mis-identified electrons mimic nuclear recoils … part-per-billion level particle ID!
Neutrons: Nuclear recoil final state. (alpha,n), U, Th fission, cosmogenic spallation
n
μ μ
NN*γ
D. Malling, UCLA DM’16
Contamination: 238U and 232Th decays, recoiling progeny and mis-identified alphas, betas mimic nuclear recoils
Jocelyn Monroe June 30, 2020 / p. 11
D. Malling, UCLA DM’16
pp solar neutrinos
20092019
DEAP, +PSD
modified from Malling, UCLA DM’16
N
Backgrounds
Ajaj et al, Phys.Rev..D100 (2019)
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Gamma ray interactions: electron recoil final states rate ~ Ne x (gamma flux), O(1E7) events/(kg day) mis-identified electrons mimic nuclear recoils … part-per-billion level particle ID!
Neutrons: Nuclear recoil final state. (alpha,n), U, Th fission, cosmogenic spallation
n
μ μ
NN*γ
D. Malling, UCLA DM’16
Contamination: 238U and 232Th decays, recoiling progeny and mis-identified alphas, betas mimic nuclear recoils
Jocelyn Monroe June 30, 2020 / p. 11
D. Malling, UCLA DM’16
pp solar neutrinos
20092019
DEAP, +PSD
modified from Malling, UCLA DM’16
N
Amaudruz et al, Phys.Rev.Lett. 121 (2018) no.7, 071801
Backgrounds
Ajaj et al, Phys.Rev..D100 (2019)
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Gamma ray interactions: electron recoil final states rate ~ Ne x (gamma flux), O(1E7) events/(kg day) mis-identified electrons mimic nuclear recoils … part-per-billion level particle ID!
Neutrons: Nuclear recoil final state. (alpha,n), U, Th fission, cosmogenic spallation
n
μ μ
NN*γ
D. Malling, UCLA DM’16
Contamination: 238U and 232Th decays, recoiling progeny and mis-identified alphas, betas mimic nuclear recoils
Jocelyn Monroe June 30, 2020 / p. 11
D. Malling, UCLA DM’16
pp solar neutrinos
20092019
DEAP, +PSD
modified from Malling, UCLA DM’16
N
Backgrounds
Ajaj et al, Phys.Rev..D100 (2019)
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Gamma ray interactions: electron recoil final states rate ~ Ne x (gamma flux), O(1E7) events/(kg day) mis-identified electrons mimic nuclear recoils … part-per-billion level particle ID!
Neutrons: Nuclear recoil final state. (alpha,n), U, Th fission, cosmogenic spallation
n
μ μ
NN*γ
D. Malling, UCLA DM’16
Contamination: 238U and 232Th decays, recoiling progeny and mis-identified alphas, betas mimic nuclear recoils
Jocelyn Monroe June 30, 2020 / p. 11
D. Malling, UCLA DM’16
pp solar neutrinos
20092019
DEAP, +PSD
modified from Malling, UCLA DM’16
N
Backgrounds
Ajaj et al, Phys.Rev..D100 (2019)
+ large, active veto detectors
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https://masterclass.icecube.wisc.edu/en/learn/detecting-neutrinos
Neutrino Energy (MeV)-110 1 10
)-1
bin
-1 s
-2 F
lux
(cm
νSo
lar
210
310
410
510
610
710
810
910
1010
1110
1210ppBe7
N13
O15
F17
B8hep
Jocelyn Monroe June 30, 2020 / p. 12
What ν signals can future dark matter detectors see?
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Prospects for Solar ν-N Coherent Scattering
Jocelyn Monroe June 30, 2020 / p. 13
DarkSide-20k ESPP 2019
European Strategy for Particle Physics, Physics Briefing Book (2019)
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Solar ν-e Event Rates
Jocelyn Monroe June 30, 2020 / p. 14
Neutrino Energy (MeV)-110 1 10
)-1
bin
-1 s
-2 F
lux
(cm
νSo
lar
210
310
410
510
610
710
810
910
1010
1110
1210ppBe7
N13
O15
F17
B8hep
example event rates of solar neutrino-electron elastic scattering at LNGS, per tonne-year of CF4
Z, W
e e
ν ν
e.g. for Ar target: DarkSide-20k estimates 10k solar neutrino- electron elastic scatters above threshold per 100 tonne-yrs
Aalseth, et al. Eur.Phys.J.Plus 133 (2018)
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Solar ν-e Event Rates
Jocelyn Monroe June 30, 2020 / p. 15
example event rates of solar neutrino-electron elastic scattering at LNGS, per tonne-year of CF4
Z, W
e e
ν ν
e.g. for Ar target: DarkSide-20k estimates 10k solar neutrino- electron elastic scatters above threshold per 100 tonne-yrs
Aalseth, et al. Eur.Phys.J.Plus 133 (2018)
Statistics even allow solar oscillation physics!
Aalbers, et al. arXiv:2006.03114
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Solar ν-e Event Rates
Jocelyn Monroe June 30, 2020 / p. 15
example event rates of solar neutrino-electron elastic scattering at LNGS, per tonne-year of CF4
Z, W
e e
ν ν
e.g. for Ar target: DarkSide-20k estimates 10k solar neutrino- electron elastic scatters above threshold per 100 tonne-yrs
Aalseth, et al. Eur.Phys.J.Plus 133 (2018)
Statistics even allow solar oscillation physics!
Aalbers, et al. arXiv:2006.03114
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Solar ν-Electron Scattering
Via neutrino-electron elastic scattering, LAr dark matter experiments can measure CNO (via spectral deformation), and CNO vs. Be-7
+with O(500 t-y), study the “solar metallicity problem”.
exclusion detection
Franco et al., JCAP 1608 (2016) 08 Cerdeno, Davis, Fairbairn, Vincent, JCAP 1804 (2018) 37
*Xe-136 background makes LXe CNO more challenging Baudis et al., JCAP 1401 (2014) 044, Baudis et al., 2006.03114
Jocelyn Monroe June 30, 2020 / p. 16
big opportunities:
1) distinguish between high vs. low metallicity.
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Solar ν-Electron Scattering
Via neutrino-electron elastic scattering, LAr dark matter experiments can measure CNO (via spectral deformation), and CNO vs. Be-7
+with O(500 t-y), study the “solar metallicity problem”.
exclusion detection
Franco et al., JCAP 1608 (2016) 08 Cerdeno, Davis, Fairbairn, Vincent, JCAP 1804 (2018) 37
*Xe-136 background makes LXe CNO more challenging Baudis et al., JCAP 1401 (2014) 044, Baudis et al., 2006.03114
Jocelyn Monroe June 30, 2020 / p. 17
big opportunities:
1) distinguish between high vs. low metallicity.
2) study non- standard solar neutrino interactions?
Aprile et al., 2006.09721 Boehm et al., 2006.11250
C. Boehm et al., 2006.11250
Xenon1T data
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What neutrino signals can future dark matter detectors see?
Jocelyn Monroe May 3, 2018 / p. 7https://masterclass.icecube.wisc.edu/en/learn/detecting-neutrinos
(if lucky!)
for a supernova at 10 kPc, expect 300-500 ν-N events in near-future experiments. • measure all flavors via NC • measure νe 40Ar e- 40K* • multi-messenger observation:
sub-eV mass ordering?
Lang et al., Phys. Rev. D 94 (2016)
Arnaud et al., Phys.Rev.D.65.033010
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What neutrino signals can future dark matter detectors see?
Jocelyn Monroe May 3, 2018 / p. 7https://masterclass.icecube.wisc.edu/en/learn/detecting-neutrinos
(if lucky!)
for a supernova at 10 kPc, expect 300-500 ν-N events in near-future experiments. • measure all flavors via NC • measure νe 40Ar e- 40K* • multi-messenger observation:
sub-eV mass ordering?
Lang et al., Phys. Rev. D 94 (2016)
Arnaud et al., Phys.Rev.D.65.033010
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What neutrino signals can future dark matter detectors see?
https://masterclass.icecube.wisc.edu/en/learn/detecting-neutrinos
Anti-Neutrino Energy (MeV)0.5 1 1.5 2 2.5 3 3.5 4 4.5
)-1
s-2
Flu
x (c
mν
Geo
-210
-110
1
10
210
310
410
510U238
U235
Th232
K40
Jocelyn Monroe June 30, 2020 / p. 19
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Jocelyn Monroe June 30, 2020 / p. 2
in a 10n T-year exposure…
study with 500 neutrino background events
Contribution from geo-neutrinos is non- to ν-e scattering rate: ~few%
Leyton, Dye, JM, Nature Commun. 8 (2017) 15989
ν-N scattering: Gelmini et al, arXiv:1812.05550
low E dominated by the (not-yet-measured) K-40 (Q = 1.3 MeV).
Example: ν-e elastic scatters per kt-yr at LNGS, on CF4
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Jocelyn Monroe June 30, 2020 / p. 2
in a 10n T-year exposure…
study with 500 neutrino background events
Contribution from geo-neutrinos is non- to ν-e scattering rate: ~few%
Leyton, Dye, JM, Nature Commun. 8 (2017) 15989
ν-N scattering: Gelmini et al, arXiv:1812.05550
low E dominated by the (not-yet-measured) K-40 (Q = 1.3 MeV).
Example: ν-e elastic scatters per kt-yr at LNGS, on CF4
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• directional dark matter detection studies show 1D direction reconstruction for nuclear recoil final states gains 10x over non-directional measurements in the presence of backgrounds
• 1 mm sampling pitch in drift direction makes direction reconstruction of ~cm length electron tracks feasible in 1D, transverse pitch is a potentially tractable challenge with SiPM readout…
potential increase in sensitivity / reduction in exposure to discovery from electron recoil direction
What about Electron Directionality?
exclusion detection
Mayet, et al., Phys.Rept. 627 (2016)
Jocelyn Monroe June 30, 2020 / p. 21
Aal
seth
et a
l., JI
NST
12
(201
7)
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Geo ν-Electron Scattering
challenge: measure the direction of ~1 MeV e- recoils
study with 500 neutrino background events
energy, time, and direction analysis shows sensitivity at 95% CL to measure K-40 flux with O(100) t-yr exposure.
example: geo-, solar-, reactor-ν -induced electron recoil directions, at LNGS.
Jocelyn Monroe June 30, 2020 / p. 22
Leyton, Dye, JM, Nature Commun. 8 (2017) 15989
… potentially opens up measurement of crust vs. mantle flux
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diffuse supernovae back- ground: perhaps within reach in large exposures if could reject neutrino scatters! (requires directional nuclear recoil detection)
Jocelyn Monroe May 3, 2018 / p. 7https://masterclass.icecube.wisc.edu/en/learn/detecting-neutrinos
Aprile et al., JCAP04 (2016) 027
What neutrino signals can future dark matter detectors see?
Albers et al., JCAP 1611 (2016)
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What neutrino signals can future dark matter detectors see?
https://masterclass.icecube.wisc.edu/en/learn/detecting-neutrinos
Energy (MeV)500 1000 1500 2000 2500 3000 3500 4000
)-1
s-2
Flu
x (c
mν
Atm
osph
eric
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-410
-310
-210µν
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Jocelyn Monroe June 30, 2020 / p. 24
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Prospects for Atmospheric ν-N Coherent Scattering
A ν background paradigm…
where the discovery reach is limited by ν flux and cross section uncertainties!
Jocelyn Monroe June 30, 2020 / p. 25
Roszkowski et al., APPEC Dark Matter Review (2020)
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Jocelyn Monroe May 3, 2018 / p. 13
What can future dark matter detectors tell us about the neutrino?
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Jocelyn Monroe May 3, 2018 / p. 13
What can future dark matter detectors tell us about the neutrino?
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exclusion detection
ν-less Double Beta Decay
Xe dark matter searches aim for competitive sensitivity, via restricted fiducial volume (inner 1 t) to reduce backgrounds, and projected 1% energy resolution at the 2ν beta decay endpoint
big opportunity: significant Xe-136 target mass (~600 kg)
big challenges: Th background, energy resolution, and nuclear matrix element uncertainty
example: projected sensitivity in LZ:
Q-value= 2458 keV
P. Bras, IDPASC 2018
Jocelyn Monroe June 30, 2020 / p. 27
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exclusion detection
ν-less Double Beta Decay
Xe dark matter searches aim for competitive sensitivity, via restricted fiducial volume (inner 1 t) to reduce backgrounds, and projected 1% energy resolution at the 2ν beta decay endpoint
big opportunity: significant Xe-136 target mass (~600 kg)
big challenges: Th background, energy resolution, and nuclear matrix element uncertainty
P. Bras, IDPASC 2018
Jocelyn Monroe June 30, 2020 / p. 28
recent demonstration of sensitivity to rare processes in XENON1T: Xe-124 2ν double e- capture XENON Collaboration, Nature 568 (2019)
example: Xenon1T energy resolution
Q-value= 2458 keV
Thanks to L. Baudis
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1) Sterile neutrino-electron scattering: NS e- νe e-
Sterile ν Signatures
2) The beta decay energy spectrum of background, e.g. Ar-39, is modified by sterile neutrino mixing.
Direct searches: limits on |Ue4|2 at 10 keV mass ~ 0.02 at 90% CL from beta decay measurements
Jocelyn Monroe June 30, 2020 / p. 29
Dragoun, Venos, Phys. 3 (2016) 77-113
Campos & Rodejohann, Phys.Rev.D 94 (2016)
Astrophysical limits on |Ue4|2 at 10 keV mass ~1E=11
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1) Sterile neutrino-electron scattering: NS e- νe e-
Sterile ν Signatures
2) The beta decay energy spectrum of background, e.g. Ar-39, is modified by sterile neutrino mixing.
Astrophysical searches: limits on |Ue4|2 at 10 keV are ~1E-11 from x-ray constraints
Jocelyn Monroe June 30, 2020 / p. 26
Dragoun, Venos, Phys. 3 (2016) 77-113
Campos & Rodejohann, Phys.Rev.D 94 (2016)
Sensitivity estimates in range between direct and astrophysical constraints (10-4-10-5)
Astrophysical limits on |Ue4|2 at 10 keV mass ~1E=11 Weinheimer, ESPPU’19
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Conclusions & Outlook
Dark matter experiments aspire to study the nature of the neutrino aiming at neutrino-less double beta decay sensitivity, sterile neutrinos,
… and today’s background may be tomorrow’s signal. (T. Kajita, 2015)
Dark matter direct detection technology is approaching the scale where neutrino physics is within reach:
coherent scattering of solar neutrinos, atmospheric neutrinos with large exposures, and geo-neutrino detection potential with very large exposures.
Future dark matter detectors should develop their electron direction measurement capability, to become neutrino telescopes!