Direct(ional) Detection of Dark Matter at Neutrino Detectors Nirmal Raj TRIUMF
with Joe Bramante, Ben Broerman (PICO), Jason Kumar, Rafael Lang (XENON1T), Maxim Pospelov and DEAP-3600 analysis: Walter Bonivento, Shivam Garg, Michela Lai, Ashlea Kemp, Shawn Westerdale + others
Neutrino Theory Mini-Workshop, 23 Sep 2020 Structure of the talk uncover direct detection regions 1 well-loved paradigms
lots of room to explore on just this space! simple new search strategies — go to optically thick limit
2 enlist neutrino detectors! 3 measure DM velocity spectrum
CMB BULLET CLUSTER Dark reality
v
LARGE SCALE STRUCTURE r GALACTIC ROTATION
CMB BULLET CLUSTER
3 Direct detection status after 1000 kg-yr exposure cross section for dark matter cross for dark section matter nucleons hitting
(cm2) dark matter mass 4 (GeV) Bird’s-eye view
10-11
10-21
10-31 ? ? 10-41
6 10 14 18 cross section for dark matter cross for dark section matter nucleons hitting 0.01 100.00 10 10 10 10
(cm2) dark matter mass 5 (GeV) All the Earth-based constraints
10-11
WEARY SKYLAB -21 RARE 10 XQC IMP CDMS-I DAMA
X1T
-31 CRESST surface 10 POWERLESS
CRESST-III XENON1T Drawn in 1999! -41 10 GHOSTLY
6 10 14 18 cross section for dark matter cross for dark section matter nucleons hitting 0.01 100.00 10 10 10 10
(cm2) dark matter mass 6 (GeV) Hunting even rarer dark matter
10-11
WEARY SKYLAB -21 RARE 10 XQC IMP CDMS-I DAMA
X1T
-31 CRESST surface 10 POWERLESS
CRESST-III XENON1T Drawn in 1999! -41 10 GHOSTLY
6 10 14 18 cross section for dark matter cross for dark section matter nucleons hitting 0.01 100.00 10 10 10 10 Is dark matter here? (cm2) dark matter mass 7 (GeV) Theoretical appeal
Super-heavy states appear in theories α of grand unification of forces. 3 α2 α 1 µ Can make them in early universe:
* Hawking radiation from primordial black holes Hooper, Krnjaic, McDermott (2019)
* Gravitationally @ final stages of inflation Chung, Crotty, Kolb, Riotto (2001), Harigaya, Lin, Lou (2016)
* Pre-heating: parametric resonance —> rapid decay of inflaton Giudice, Peloso, Riotto, Tkachev (1999), Bai, Korwar, Orlofsky (2020)
* Thermally! Kim, Kuflik (2019) 8 Heavy, strong, stable: recent wave
Electroweak symmetric monopoles Bai, Korwar, Orlofsky 2005.00503 Electroweak symmetric solitons Bai, Jain, Ponton 1906.10739 Charged primordial black holes Lehmann, Johnson, Profumo, Schwemberger Asymmetric dark matter nuggets 1906.06348 Coskuner, Grabowska, Knapen, Zurek 1812.07573 Dark blobs Grabowska, Melia, Rajendran 1807.03788 Colored relics Gross, Mitridate, Redi, Smirnov, Strumia Heavy dark baryons 1811.08418 Davoudiasl, Mohlabeng 1809.07768 Heavy dark skyrmions Berezowski, Dick Why now? Sep 2019 Can detect them now! 9 Today’s dark matter detectors
DAMA 1999 10 cm (Q1) Can current DM detectors hunt the rarest huntable? max mDM 10 cm = 1016 GeV B. Broerman, J. Bramante, R. Lang, N. Raj Phys.Rev.D. (2018)
100 cm 130 cm 50 cm
XENON1T/ DEAP-3600 PICO-40L LUX/ PANDAX-II 10 Multiscatter signatures essential # scatters per transit = � x target number density x path length B. Broerman, J. Bramante, R. Lang, N. Raj Phys.Rev.D. (2018) RARE
MANY SCATTERS ONE SCATTER cross section
GHOSTLY dark matter mass Multiscatter signatures essential # scatters per transit = � x target number density x path length B. Broerman, J. Bramante, R. Lang, N. Raj Phys.Rev.D. (2018) RARE
MANY SCATTERS ONE SCATTER cross section
GHOSTLY Goodman & Witten, 1985: dark matter mass
- DAMA ’99 based on this ‘multiple scatters’ signature - Not sought any more. Would double the reach of all current experiments! (Q2) Are there bigger detectors that can join the hunt?
B. Broerman, J. Bramante, J. Kumar, R. Lang, M. Pospelov, N. Raj Phys.Rev.D. (2018)
+
BULLET CLUSTER
XENON1T DEAP-3600 PICO-40L
13 recasting MAJORANA DEMONSTRATOR search for lightly ionizing particles
‘Direct Detection Limits on Heavy Dark Matter’ 2009.07909 M. Clark, R. Lang et al 14 Liquid scintillator neutrino detectors
XENON1T, DEAP, PICO, … BOREXINO, SNO+, JUNO
Direct detection @ liq. scint. neutrino detectors
Mass sensitivity: dark matter fluxes at least 100 times greater Cross section sensitivity: Satisfy selection trigger
15 SNO+ mass reach
“fiducial area” = 106 cm2 ��-��
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DM transit = 10 µs
Continuous deposition of photoelectrons over transit time
Collinearity
may be exploited with vertex reconstruction/ timing information
17 Signal vs background windows
BOREXINO, 10 µs windows
dark matter signal, σnx = 10-28 cm2 (spin-independent)
typical windows with dark counts
1 in 100 windows 14C x
once in 10 years
x x x x x
18 SNO+ cross section reach
B. Broerman, J. Bramante, J. Kumar, R. Lang, M. Pospelov, N. Raj Phys.Rev.D. (2019) ��-�� ������ ��� ������� ���� -�� �� ����������
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���������� �������� ������� ��������� ��-�� ���� ���� ���� ���� ���� ���� ���� �χ (���) 19 Reconstructing dark matter velocity vector
Image: Borexino 1308.0443
dark matter path
PMT “hot spots” with numerous illuminations => dark matter direction & path length + timestamps => dark matter speed J. Bramante, J. Kumar, N. Raj 20 Phys Rev D (2019) VelocityTestingDetector vector dispersion resolutions uncertainties speed J. Bramante, J. Kumar, N. Raj Phys Rev D (2019) (PMT spacing/ path length)
~2 degrees, c.f. Cygnus spanning > 20 degrees VelocityTestingDetector vector dispersion resolutions uncertainties speed J. Bramante, J. Kumar, N. Raj Phys Rev D (2019) (PMT spacing/ path length)
(< 1 km/s) detector timing resolution
detector uncertainties tiny => smearing negligible => main limitation is statistics! (triumph of experimental progress)
22 Statistics
SNO+ could potentially collect these many events
J. Bramante, J. Kumar, N. Raj 23 Phys Rev D (2019) Dark astrometry
reconstruct velocity vector event-by-event
assemble distributions of speed and angle
determine halo properties!
dispersion speed escape speed anisotropies + bonus: reject backgrounds
J. Bramante, J. Kumar, N. Raj 24 Phys Rev D (2019) Pinpointing mean speed galactic frame
v0 = circular speed = √(2/3) dispersion speed
1400 v0 = 180 km/s 1200 v0 = 220 km/s 1000 v0 = 260 km/s 800
600
400
200 Distribution in galactic frame 0 0.0000 0.0005 0.0010 0.0015 0.0020 v/c J. Bramante, J. Kumar, N. Raj 25 Phys Rev D (2019) Pinpointing mean speed galactic frame
circular speed = 220 km/s
J. Bramante, J. Kumar, N. Raj 26 Phys Rev D (2019) Testing velocity anisotropies angular distribution: galactic frame
m contribution SPHERICAL HARMONICS l monopole ~ 1
dipole ~ ε quadrupole ~ ε
test anisotropy, ε << 1
Benchmark: =>
J. Bramante, J. Kumar, N. Raj 27 Phys Rev D (2019) Testing velocity anisotropies monopole coefficient dipole coefficient
good angular resolution (smearing negligible)
poor angular resolution (smearing significant)
LESSONS: good statistics => accuracy & precision, J. Bramante, J. Kumar, N. Raj smearing => anisotropies wash out. Phys Rev D (2019) Takeaways
Amazing advances in underground detection technology => - metre-scale dark matter experiments (Xenon1T, DEAP, PICO) can discover dark matter [composites, heavy baryons, nuggets, blobs, black holes, monopoles, solitons, …] near/beyond Planck mass, through dedicated multi-scatter signature search.
- large-volume neutrino experiments with liquid scintillator (SNO+, JUNO) can join the dark matter “direct detection” program, probe well beyond Planck mass, determine halo properties with unprecedented precision. (dispersion speed, escape speed, velocity anisotropies)
29 THANK YOU!
QUESTIONS? (Q1) Identifying multiscatterers DEAP-3600 @ SNOLAB back-of-the-envelope:
waveform analysis
increasing cross sec PE count
t 31 (Q1) Identifying multiscatterers DM transit = 2.5 µs LUX/PANDAX/XENON1T PICO-60
single hit:
Train of scintillation pulses + Track of bubbles electroluminescence pulses multi-hit: For multiplicity > 5 (>500), S2 (S1) Stereo cameras can image up to pulses merge into elongated pulses 100 bubbles (mm resolution)
- Background ~ 0 (from daughter neutrons of surrounding material & coincident electron recoils)
Searches ongoing…
32 (Q2) Large volume neutrino detectors?
Organic liquid scintillator (SNO+, Borexino, etc.): well-suited for dark matter search! collect enough light in PMTs => in business
Water Cerenkov (Super-K, SNO, etc.) unsuitable: non-relativistic scattering
Liquid argon TPCs (DUNE, etc.): threshold too high
33 SNO+
scale model @ SNOLAB PMT selfie 2 km underground
34 SNO+ cross section reach: triggers
Existing @ BOREXINO Proposed improvement 50 keV/ 100 ns => 50 PE /100 ns, or 42 PE/ 10 µs. 5000 PE/ 10 µs.
The Scintillation Efficiency of Carbon and Hydrogen Recoils in an Organic Liquid Scintillator for Dark Matter Searches Hong, Craig, Graham, Hailey, Spooner, Tovey
[Bicron scintillator (BC505)]
35 SNO+ cross section reach: triggers
DM transit = 10 µs Existing @ BOREXINO Proposed improvement 50 PE /100 ns, or 5000 PE/ 10 µs. 42 PE/ 10 µs.
— Enhance cross section sensitivity by ~100.
36 SNO+ cross section reach: triggers
DM transit = 10 µs Existing @ BOREXINO Proposed improvement 50 PE /100 ns, or 5000 PE/ 10 µs. 42 PE/ 10 µs.
Dark count rate reported by Borexino (1308.0443): Nbg = 10 PE/ 10 µs. main background
— Enhance cross section sensitivity by ~100.
37 SNO+ cross section reach: triggers
DM transit = 10 µs Existing @ BOREXINO Proposed improvement 50 PE /100 ns, or 5000 PE/ 10 µs. 42 PE/ 10 µs.
Dark count rate reported by Borexino (1308.0443): Nbg = 10 PE/ 10 µs.
— Get required trigger from trial factors (solve for Nc)
(10 yr) — Enhance cross section sensitivity by ~100.
38 SNO+ cross section reach
B. Broerman, J. Bramante, J. Kumar, R. Lang, M. Pospelov, N. Raj Phys.Rev.D. (2019) ��-�
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sensitivity set by scattering on 13C �χ (���) 39 HalometryTesting at SNO+: dispersion speed speed distribution
Sun’s frame
J. Bramante, J. Kumar, N. Raj 40 Phys Rev D (2019) Testing dispersion speed
Sun’s frame
Perform a Kolmogorov-Smirnov test (“How many events to reject null hypothesis at given significance?”)
J. Bramante, J. Kumar, N. Raj 41 Phys Rev D (2019) Pinpointing escape speed?
Sun’s frame
escape speed on tail => hard to reconstruct faithfully from moments of distribution
J. Bramante, J. Kumar, N. Raj 42 Phys Rev D (2019) Testing escape speed
Sun’s frame
null hypothesis: vesc = 600 km/s
1 event above v 2.3 events in [600 km/s, v] (90% C.L., Poissonian) J. Bramante, J. Kumar, N. Raj 43 Phys Rev D (2019) Rejecting backgrounds
Unknown instrumental/ radiogenic/ cosmogenic background modelled as power-law.
(NB: in all probability, search would be background-free.)
Kolmogorov-Smirnov test to determine # events required to reject background
J. Bramante, J. Kumar, N. Raj 44 Phys Rev D (2019) Characterizing WIMPs
Encounter rate (spin-independent) =
6.8 events ⇥ 4 N A 1000 GeV 27 ⇢DM vDM 39 2 3 /kg/day 10 cm 27 mDM A 0.3 GeV/cm ! 220 km/s ⇣ ⌘ ✓ ◆ ✓ ◆✓ ◆ ✓ ◆
x Redundancy in 3
cm {cross-section, / mass, DM ⇢ local density} 3 GeV . 0
45 Characterizing MIMPs
cross-section
# scatters per transit target number density detector dimension
46 Characterizing MIMPs
N(scatters) ∝ DM kinetic energy / recoil energy ( More accurately: n L m v2 / recoil energy shield shield / )
Dark matter tracks => measure max angle of entry => angle of rejection in Earth underburden in this band => mass
47 Characterizing MIMPs
local density velocity run-time mass flux detector area
48 Summary
Near-future: multiscatter + repurposed neutrino detectors
10-11
SKYLAB
-21 10 XQC IMP CDMS-I DAMA
X1T SNO+
-31 CRESST surface 10 X1T
CRESST-III XENON1T 10-41
6 10 14 18 cross section for dark matter cross for dark section matter nucleons hitting 0.01 100.00 10 10 10 10
(cm2) dark matter mass 49 (GeV) 10-11
here: bounds from CMB SKYLAB
-21 & gas clouds in Milky Way RARE 10 XQC IMP CDMS-I
X1T
-31 CRESST surface 10 POWERLESS
CRESST-III XENON1T 10-41 GHOSTLY
6 10 14 18 cross section for dark matter cross for dark section matter nucleons hitting 0.01 100.00 10 10 10 10
(sq cm) dark matter mass 50 (GeV)