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.,...
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
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-
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
2008: Neutrino Backgrounds to Dark Matter Searches and Directionality
Jocelyn Monroe May 30, 2008
2008 2020: Neutrino Backgrounds Signals in Dark Matter Searches (and Directionality)
Jocelyn Monroe May 30, 2008
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
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
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
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
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
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
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)
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)
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)
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
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?
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)
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)
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
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
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.
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
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
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
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
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
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
• 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)
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
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)
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
-510
-410
-310
-210µν
µνanti-
_eν
_eνanti-
Jocelyn Monroe June 30, 2020 / p. 24
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)
Jocelyn Monroe May 3, 2018 / p. 13
What can future dark matter detectors tell us about the neutrino?
Jocelyn Monroe May 3, 2018 / p. 13
What can future dark matter detectors tell us about the neutrino?
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
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
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
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
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!