暗黒物質 by 方向感度検出器
東邦大学
中 竜大
2019.7.5-6 Dark Matter懇談会2019@早稲田大学

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Dark Matter in our galaxy
solar system

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Local dark matter density:0.4+0.1
GeV/cmCenter of galaxy

 Independent value on dark matter model Very much mount of DM is condensed in the halo becausemean dark matter density in the universe is ~ 1.4 keV/cm3(27 % of critical density ratio)

Astrophys. J. 295: 422-436, 1985

Dark matter flux on the earth
Solar system
22~ 100000 /cm /sec @ 100 GeV/c dark matter2

Idea of “directional” dark mater search3Direct Dark Matter SearchCenter of galaxy

Dark matter wind
( from Cygnus ）Direct dark matter search

Dark matter wind

Annual modulation
Solar system
Annual Modulation

 DAMA/LIBRA : 2.46 ton・y, 12.9σ
 (Nucl. Phys. At. Energy 19 (2018) 307-325)

arXiv:1805.10486

2-3 % variation

Diurnal Modulation

0.01- 0.1 % signalvariation
 Anisotropic
for angular distribution
 Actively observation with lower statistics4
 Currently technical R&D is neededPotential of Directional Sensitive Search
Likelihood ratio

SignalN. Agfanova et al. (NEWSdm collaboration)
Eur. Phys. J. C (2018) 78: 578

cygnusBackgroundsignal pdf

total number of observed events

background pdf

set of observables

Direction information : Several 10 events
Gain of 100 times

Annual modulation : Several 1000 events

Nobs=20

Background10

expected number ofbackground events

Likelihood ratio

expected number of
WIMP events

Signal1001000

WIMP mass [GeV/c2]

SignalBackgroundNobs=1305WIMP mass [GeV/c2]

Velocity distribution
 Dark mater interaction with gas or something is
negligible to standard matter interaction each other.
 Dark matters are distributing as thermal equilibrium

Maxwell distribution
１2/𝑣 2𝑓 𝑥 =exp(−𝑣+𝑣𝐸/0π𝑣02 3 2v0: velocity of the solar systemvE: Earth’s velocity relative to DM

It’s big assumption for local scale6

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Slide from S. Masaki @ 2018年新学術領域B02若手研究会（名古屋大学）

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ER onlyanisotropic

90%
true value
68%

Dark matter mass [GeV/c2]

LikelihoodStudycos only
Direction sensitiver
Anisotropyr
Anisotropyparameter

isotropicr
parameter
Anisotropyr
Anisotropy

Potential of direction sensitive search

Ethr=50keV (F)Mdm=60GeV#event: 1000

K. Nagao, H. Ikeda, K.
Miuchi and TN
Dark matter mass [GeV/c2]

cf. Samuel K. Lee and, Annika
9H.G. Peter, arXiv:1202.5035

Neutrino coherentν scattering
νZ0

Observation of COHERENT detector by Spallation neutron source (SNS)@Oak Ridge National Laboratory

14.6 kg CsI scintillator

134 +- 22 events observed(173 +- 48 predicted)
Profile Likelifood fit → 6.7σ

PRD 89, 023524 (2014)

Science 15 Sep 2017:10Vol. 357, Issue 6356, pp. 1123-1126

Over the neutrino floor

Solar neutrino

WIMP

8B

Target : Xe
Er : 0 – 5 keV
WIMP mass : 6 GeV/c2
Cross section : 4.9 x 10-45 cm2
Case of 8B neutrino

Angle difference between WIMP and solar neutrino : 60 – 120 °Atmosphericneutrino

Ciaran A. J. O’Hare et al.,Phys. Rev. D 92, 063518 (2015)11

Technologies for direction sensitive detectors

Track length
Difficulties

Gaseous detector
0.1 – 1 mmPoor target mass
Diffusion of drift electrons

Solid detector
0.1 – 1 µm
Readout technologiesUnderstanding of BG

Angular resolution

Several 10 °Several 10 °12

Current experimental effort
Gaseous TPC

 DRIFT NEWAGE DM-TPC MIMAC D3Solid detector

 NEWSdm(fine-grained nuclearemulsions) ZnWO4 scintillator

and some R&D project13

Gaseous TPC
MWPC (DRIFT)μPIC (NEWAGE)

Gas pressure : ~ 0.1 atm
Readout : drifted electron and each readout technologies
Target : C, F, S, He

Readout

Target

DRIFT

MWPC

CS2, CF4

NEWAGE

μPIC

CF4 , SF6MIMAC

Micromegas

CF4, C6H10D3ATRAS Pixel chips

He+CO2, SF614

Spin-dependent directional search limit with Gaseous detector

CF4 at 0.1 atm (50 keVee threshold@Kamioka
新学術領域「宇宙の歴史をひも解く地下素核研究」2019領域研究会

15NEWSdm project with super-fine nuclear emusions
Super-resolution

500nm

1 um

Detector : Super-resolution nuclear emulsions
Site : Grann Sasso Laboratory
Target : CNO (light DM) + ArBr (Heavy DM)
Readout : optical based microscope system

C 60 keV
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Concept of NEWSdm experiment LNGS Hall.F
Device self-production
Super-high resolution device

Surface laboratory
exposure on the telescope

Underground laboratoryChemical development
treatment
Readout + analysis
Using microscope techniques

17Anisotropic scintillator [ZnWO4]ADAMO groupα/β比55% の異方性があることを報告

Eur. Phys. J. C (2013) 73:2276

Assuming 7% anisotropy @5keVnr in ZnWO4
104 ton・day for 10-48 cm2 (neutrino floor)
From 関谷洋之, JPS meeting
201718

Demonstration for anisotropic response~ 880keV monochromatic neutron test
@ AIST (T(p,n) reaction)

α-ray
14 % anisotropy observation for 150 keVnr O
recoilDirect detection of nuclear
recoil due to neutron by TOF

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ピーダーセン珠杏氏のスライドより引用

New Idea
Diamond
Microscope imaging of luminescence due to N-V center in diamondPhys. Rev. D. 96 035009 (2017)

 Carbon nano tube
Carbon nanotube target + gaseous TPC
arXiv:1412.8213 [physics.ins-det]

 Columnar recombination with high pressure gas
Dependence of Recombination efficiency on direction between
nuclear recoil and drift field
J. Phys. Conf. Ser. 460, 012006 (2013).
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Conclusion
 Anisotropic flux of dark matter on the earth is expected, and it’s sound information for direct dark matter
detection if we can obtain that.
 Direction information give strong and high reliable evidence for dark matter discovery and the properties.
- essentially difference systematic from annual modulation- statistical gain for discovery- velocity distribution- beyond the neutrino floor Currently various experiment and technologies are studied and promoting
current actively effort- gaseous TPC- fine-grained nuclear emulsion- ZnWO4 anisotropic scintillator
new idea and feasibility study- Diamond, carbon nano-tube, high pressure Xe with colamner recombination

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