暗黒物質直接探索 by 液体希ガス(Review)

山下雅樹
東京大学宇宙線研
2019/7/5 暗黒物質懇談会@早稲田大学
Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita

内容• 検出原理の紹介• 暗黒物質直接探索の動向 + 伏見さん(NaI)+中さん(方向)• 暗黒物質探索実験 (現状)
• LXeTPC, LArTPC• 幅広い質量領域へのチャレンジ• 暗黒物質探索実験 (近い将来 2020-)• WIMP以外のターゲットは?
• pp solar neutrino, 二重ベータ崩壊、捕獲, 超新星

Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita

2

DM探索

Colliders
LHC, ILC ...

χ

χ

SM

SM

indirect
SK, CTA, CALET ...

directXMASS, XENON, LZ …

Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita

3

Interaction with dark matter
Goodman and Witten PRD(1985)

nuclear recoil

fast neutron
WIMPelectronic recoil-U/Th/40K etc background

WIMPとターゲット原子核の弾性散乱
Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita

4Interaction with dark matter
Goodman and Witten PRD(1985)

nuclear recoil

electronic recoil

fast neutron
WIMP-U/Th/40K etc background- light mass DM ( < 1 GeV)
最近ではModelと実験の進展があり反跳電子もチャンネルも開拓されている

Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita

5検出器に落とすエネルギー
WIMP 原子核の弾性散乱
ER = r

(1

cos )
EW
2

(center of mass)

4M w M Nr =( M w + M N )2
簡単のために

原子核

WIMP

θ

θ
rth ~4500 nm

Mw = 100 GeV/c2 , MT = 100 GeV/c2 , r = 1とすると非相対論的速度(WIMP velocity: v~ 220 km/sec = 0.75 X 10-3 )2 (0.75 x 10 -3) c2
1
=
1/2
x
100
x
GeV/c
2 2
ER =
MW c
= 30 keV2

track

100 nmarXiv:1207.2292v3

Figure 14. Xe recoil tracks in liquid xenon simulated with TRIM [62] compared with the
distance (calculated in [134]). The projectile trajectory is shown in red; trajectories of second
Masaki Yamashita
Kamioka Observatory,
ICRR,
University
are in graywithTheend
pointsofinTokyo
green (this shows the number of secondary atomic
recoils in6 th観測される頻度
Expected spectrum:

R0 F 2 (ER ) k0 1 ! vmax 1
dR
3
=
f
(v,
v
)d
v
E
v
dER
E0 r
k 2πv0min v

検出器
motion dynamics
R0: Event rate

F: Form Factor(depends on atomic
nuclei）

暗黒物質や地球の運動力学=> 季節変動

Maxwellian distribution for DM velocity
is assumed.
V :velocity onto target,
VE: Earthʼs motion around the Sun

暗黒物質の密度や断面積

Spin independent
22 µT
σ0 = A µ2 σχ−ppKamioka Observatory, ICRR, The University of Tokyo

Spin dependent(λ2N,Z J(J+1))Nuclear µ2
σ0 = (λ2 J(J+1))proton µT2 σχ−ppp,ZMasaki Yamashita

75GeV Mass
5GeV:1e-41cm2
Xe
I
Ge
Na

10

1

10−1

10

10−4

100GeV Mass
Xe

10−3

100GeV:1e-45cm2
Xe
I
Ge
Na

I

Ge

−4

10

Na

10−2

−3

Integral[events/day/kg]

Integral[events/day/kg]

Integral spectrum

Xe
0

Ge

I
2

4

10−5

6

8
10
Energy[keVnr]

エネルギーしきい値が重要

Kamioka Observatory, ICRR, The University of Tokyo

10−6

Na
0

10

20

30

40
50
Energy[keVnr]

検出器の質量が重要

Masaki Yamashita

8derived from the charge signal or from a combination of light and charge is therefore necessary
to optimise the sensitivity, as discussed in Section 5.7.
We have studied the reconstruction of WIMP properties, namely mass and scatteringcross section, from the measured recoil spectra. In a numerical model, we have incorporated
realistic detector parameters, backgrounds and astrophysical uncertainties [42]. Our primarystudy was directed towards spin-independent WIMP-nucleon interactions; however, given• 我々の周りにDMが存在!
DARWIN’s excellent sensitivity to spin-dependent interactions, especially for 129 Xe [51], it
canbe extended to axial vector couplings as well. Figure 3 (left) shows the reconstructed• DMの質量と断面積
parameters for three hypothetical particle masses and a fixed cross section of 2 ⇥ 10 47 cm2 ,• 例えば200 ton x year exposure (cross section ~XENON1T sensitivity )assuming an exposures of 200 t⇥y [42]. The corresponding number of events are 154, 224
2 , 100 GeV/c2 and 500 GeV/c2 , respectively. Usand
60,
for
WIMP
massesof20
GeV/c• 100 GeV 以上は上限値が困難
ing the same exposure, Figure 3 (right) shows the reconstructed mass and cross section• 他の原子核と合わせれば可能。例えばAr

直接探索から得られるもの

20GeV
154 evts

100GeV224 evts

500GeV
60 evts

100GeV
2240 evts
224 evts
22 evts

neutrino floor

neutrino floor

arXiv:1606.07001
Figure 3. The 1 and 2 credible regionsof themarginal posterior probabilities for simulations ofcoherentscatter
WIMP signals assuming various masses and spin-independent (scalar) cross sections with DARWIN’s
LXe target. The width and length of these contours demonstrate how well the WIMP parameters
can bereconstructed
DARWINafter
a 200 t⇥y exposure. The ‘⇥’ indicate the simulated
benchMasaki
Yamashita
Kamioka
Observatory,
ICRR,inThe
Universityof Tokyo希ガス液体による探索

Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita

暗黒物質直接探索は激しい国際競争
SNOLAB
DEAP-CLEAN
Picasso
COUPP

BoulbyNaIADZEPLIN I/II/III
DRIFT I/II

FrejusEDELWEISS I/II
SoudanCDMS II
CoGENT

CanFranc
IGEX
ROSEBUDANAIS
ArDM

YangYang
KIMS, COSINE
Gran Sasso
DAMA/LIBRACRESST
XENON
DarkSide
NEWSSouth Pole
DM-IceKamioka Observatory, ICRR, The University of Tokyo

Kamioka
XMASS
NEWAGEJINPINGPANDA-X
CDEX

Masaki Yamashita

Masaki Yamashita

But 1249 Dark Matter users spread out

Area corresponds to number of people based on most recent publication from any experiment that has published scientific papers in the last two
years. This relied on Inspire-HEP. I almost certainly missed an experiment . Number of authors also does not correspond to FTEs since not all
experiments require collaborators be 100% committed to that experiment. See gist for calculation notes. 16/March/2019

DA
MA

LZ

XENON1T & nT

PandaXDMIce

XENON100
LUX
DAMIC

XMASS

PICO
DEAP

DarkSide

ArDM
Kamioka Observatory, ICRR, The University of Tokyo

SuperCDMSNEWSG

CRESST

SABRE

CDEX

COSINE

Chris Tunnel@HOW 2019

Masaki Yamashita

12

Dark Matter Detection community big

Area corresponds to number of people based on most recent publication from any experiment that has published scientific papers in the last two
years. This relied on Inspire-HEP. I almost certainly missed an experiment . Number of authors also does not correspond to FTEs since not all
experiments require collaborators be 100% committed to that experiment. See gist for calculation notes. 16/March/2019

過去2年のauthor リストから

Σ Dark Matter:
1249

DUNE:
1099

ATLAS + CMS:
5214
LHCb:
852
Kamioka Observatory, ICRR, The University of Tokyo

Chris Tunnel@HOW 2019

Masaki Yamashita

13

sSI@cm2D for a 50 GeVêc2 WIMP

30年に及ぶ暗黒物質探索
Evolution of the WIMP-Nucleon sSI
-40

10

-41

‡‡

10

Ge

‡

10-42
10-43

‡

極低温検出器ÊÊ ÊÊ Ê
ÚÊ

DarkSide-50
Ú
Ê
Ú
Ê
Xe10
Ú
Ú Ì
Xe100
Ú
Á
ÌÌ
LUX
Û ı
希ガス液体
LUX Û
Á
Ì
XENON1T
Û

10-44
10-45
10-46
10-47
10-48

XENONnT
LZ

10-49
Coherent Neutrino Scattering

1985

1990

1995

2000

2005 2010 2015 2020 2025
from arXiv:1310.8327v1
Year
tory
and projected evolution with time of spin-independent WIMP-nucleon
cr
Masaki Yamashita
Kamioka Observatory, ICRR, The University of TokyosSI@cm2D for a 50 GeVêc2 WIMP

30年に及ぶ暗黒物質探索
Evolution of the WIMP-Nucleon sSI
-40

10

-41

Ge

‡‡

‡

10

10-42
10-43
10-44
10-45
10-46
10-47
10-48
10-49

Figure 5.7: PTFE reflector and wire structure.

2000頃

この部屋下
1990

極低温検出器ÊÊ ÊÊ Ê
ÚÊ

DarkSide-50
Ú
Ê
Ú
Ê
Xe10
Ú
Ú Ì
Xe100
Ú
Á
ÌÌ
LUX
Û ı
希ガス液体
LUX Û
Á
Ì
XENON1TÛ

XENONnT
LZ

Coherent Neutrino Scattering

46

1985

‡

1995

2000

2005 2010 2015 2020 2025
from arXiv:1310.8327v1
Year
tory
and projected evolution with time of spin-independent WIMP-nucleon
cr
Masaki Yamashita
Kamioka Observatory, ICRR, The University of Tokyo

Liquid Rare GasZ(A)Boiling Point
at 1 atm [K]Density[g/cm3]ionization[ e-/keV]

scintillation[photon/keV]Ar

18(40)

87.3

1.40

42

40

Xe

54(131)

165

3.06

64

46

液体キセノン (-100℃）

Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita

16

Dual-phase Time Projection Chamber(LXe, LAr)rimination: Electron or Nuclear
RecoilWIMP or
nuclearrecoilNeutronnuclearrecoilMatter Detection with LXe TPCs

Gamma orElectron S1

Energy- S1 area- S2 area
Position- x-y (S2 signal)- z (drift time)
Interaction typeS2(ER/NR)time- S2/S1 ratio

S2

background-likeelectronrecoilsignal-like

Kamioka Observatory, ICRR, The University of Tokyo

electron

S1
Masaki Yamashita

17

observed in the predefined DM search region.
After
unblinding,we tabulated events surviving each cut,
WIMPs collide with argon nuclei →nuclearrecoils
as shown in Table V. The order that the cuts were applied is
not meaningful—the order shown in the table was chosen
LAr scintillates ~40 photons/keV.
Electroto be informative. Each of the last two events in TableV
was cut by both the prompt and delayed veto cuts. They are
the events in the box in Fig. 6 labeled “Radiogenic” andSinglet state with τ = 6 ns.
“Fission candidate.”

波形弁別(LAr: DarkSide, DEAP..)
Triplet state with τ = 1.6 µs.

Use pulse shape to distinguish:
Nuclear recoils (e.g. WIMPs) – mostly prompt lightElectronic recoils (e.g. Ar39) – mostly late light

N recoil

Nucleafprompt = ratio of light in first 100 ns. to total for event

e-/gamma

FIG. 11. Observed events in the f90 vs S1 plane surviving all
cuts in the energy region of interest. The solid blue outline
indicates the DM search region. The 1%, 50%, and 99% f90
acceptance contours for 8
nuclear recoils, as derived from fits to our241
AmBe calibration data, are shown as theMasaki
dashedlines.
18
Yamashita

10 rejection有効体積カット

Backgrounds

Edges

Homogeneous

MeVMaterials
ガンマ線が(β, γ) 85Kr, 222Rn
数keV有効体積にエネルギーを落とし

Surface (210Pb) Accidental
その後、検出器を~1m通り抜けるのは非常にまれ= > Neutrons~ 105 減らす

Xenon1T

coincidenceν-nucleus(内部バックグラウンド削減が鍵とな
る, Kr, Rn,)

Low-energy (cS1 < 200 p.e.) event distribution
LXe
Fiducial volumeof 1.3 tons (red line)

XeHigh
Z(=54)High Density ~3g/cc

18

19
19

XMASS
Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita

10
10−2

−4

−3

−2

−1

0

1

the recombination at low energy (≲2 keVee ). The resulting
light and charge yields after fitting are consistent withmeasurements [33,36–38]. The fit posterior is used to
predict the ER and NR distributions in the analysis
space of the DM search data, achieving an ER rejectionof 99.7% in the signal reference region, as shown in Table I.
ER uncertainties in (cS1, cS2b ) are propagated for statistical inference via variation of the recombination and its
fluctuation, as these show the most dominant effect on
sensitivity (here defined as the median of an ensemble ofconfidence intervals derived under the backgroundonly hypothesis [39,40]). For WIMP signals, the uncertainties from all modeled processes are propagated into an
uncertainty of 15% (3%) on the total efficiency for
6 ð200Þ GeV=c2 WIMPs.
Energy deposits in charge- or light-insensitive regions
produce lone S1 or S2, respectively, that may accidentallycoincide and mimic a real interaction. The lone-S1 spectrum is derived from S1 occurring before the main S1 in
high-energy events and has a rate of [0.7, 1.1] Hz. The

XENON1T (PRL2018) 1 ton year exposure(cS2b - µER) / σER

4. Background and 200 GeV=c2 WIMP signal best-fit
ictions, assuming σ SI ¼ 4.7 × 10−47 cm2 , compared to DM
ch data in the 0.9 ton (solid lines and markers) and 1.3 tons
ted lines and hollow markers) masses. The horizontal axis
he projection along the ER mean (μER ), shown in Fig. 3,
malized to the ER 1σ quantile (σ ER ). Shaded bands indicate
68% Poisson probability region for the total BG expectations.

e-coincident 214Bi − 214Po decays, respectively, simiy to the method used in Ref. [25]. The correspong event rates in the ROI are (71 ! 8) and! 4Þ events=ðton yr keVee Þ. The total ER backgroundis stable throughout both science runs and measured as
5−3 ðsystÞ ! 3ðstatÞ& events=ðton yr keVee Þ after correcfor efficiency, which is the lowest backgroundeved in a dark matter detector to date.
he NR background includes contributions from radioic neutrons originating from detector materials, coherelastic neutrino nucleus scattering (CEνNS) mainly
m 8B solar neutrinos, and cosmogenic neutrons fromondary particles produced by muon showers outside theC (negligible due to the muon veto [11]). The CEνNS
is constrained by 8B solar neutrino flux [26] and crossion [27] measurements. The rate of radiogenic neutronsmodeled with GEANT4 MC [28,29] using the measured
oactivity of materials [30], assuming a normalization
ertainty of 50% based on the uncertainty in the
RCES 4A [31] code and the difference between theNT4 and MCNP particle propagation simulation codes. Fast neutrons have a mean free path of ∼15 cm in LXe
produce ∼5 times more multiple-scatter than singleter events in the detector, allowing for backgroundpression. A dedicated search for multiple-scatter eventss nine neutron candidates, consistent with the expectn of (6.4 ! 3.2) derived from the GEANT4 and detector
onse simulation described below, which is used toher constrain the expected single-scatter neutron event
in DM search data.
he detector response to ERs and NRs is modeled
ilarly to the method described in Refs. [5,33]. Alln, 241AmBe, and neutron generator calibration data
m both science runs are simultaneously fitted to account

WIMP(200GeV)領域

TABLE I. Best-fit, including a 200 GeV=c2 WIMP signal plus
background, expected event counts with 278.8 days live time in
the 1.3 tons fiducial mass, 0.9 ton reference mass, and 0.65 toncore mass, for the full (cS1, cS2b ) ROI and, for illustration, in the
NR signal reference region. The table lists each background (BG)
component separately and in total, as well as the expectation for
the WIMP signal assuming the best-fit σ SI ¼ 4.7 × 10−47 cm2 .
The observed events from data are also shown for comparison.
Although the number of events in the reference region in the
1.3 tons fiducial mass indicate an excess compared to thebackground expectation, the likelihood analysis, which considers
both the full parameter space and the event distribution, finds no
significant WIMP-like contribution.
Mass (ton)

1.3

1.3

0.9

0.65

(cS1, cS2b )FullReference

Reference

ReferenceER
NeutronCEνNS
AC
Surface627 ! 18 1.62 ! 0.30 1.12 ! 0.21 0.60 ! 0.13
1.43 ! 0.66 0.77 ! 0.35 0.41 ! 0.19 0.14 ! 0.07
0.05 ! 0.01 0.03 ! 0.01
0.02
0.01
þ 0.27
þ 0.06
þ 0.030.02
0.47−0.00
0.10−0.00
0.06−0.00
0.04þ−0.00
106 ! 8 4.84 ! 0.40
0.02
0.01

Total BG
WIMPbest-fit

735 ! 20
3.56

Data

739

Kamioka Observatory, ICRR, The University of Tokyo

7.36 ! 0.61 1.62 ! 0.28 0.80 ! 0.14
1.70
1.16
0.83
14

2

2

Masaki YamashitaPhys.Rev.Lett. 121 (2018) no.11, 111302
Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita低質量DMへの進展

Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita≈≈figure shows the fraction of events surviving in sequenc
the fiducial
volume cut,the simulated trigger condition, andDark Sector Candidates, Anomalies,
and SearchTechniques
the S2 identification cut. The hardware trigger efficiency i
30M
keV
MeV
GeV
TeV
PeV
zeV aeV feV peV neV µeV meV eV100% for S2 pulses above 30 PE, which is well below th
analysis thresholdWIMPs
of N e− ¼ 4e− or recoil energy o
QCD Axion
0.1
keVee. The trigger efficiency Blackdecreases
below thiUltralight Dark Ma5er
Hidden Sector Dark Ma5er
Holes
point
due tothe/ slow
timescaleof S2 pulses. The detecto
Pre-InﬂaIonary Axion
HiddenThermalRelics
WIMPlessDM
acceptanceis 0.43
Post-InﬂaIonary Axion
AsymmetricDM" 0.01 above 30 PE with the dominan
acceptancelossDMdue to the restricted fiducial region. Thi
Freeze-In
SIMPs / ELDERS
matches
the acceptance of (0.42 " 0.01) found with thsame Beryllium-8
cuts applied to 39Ar events from the DarkSide-50
Muon g-2
campaign
with an AAr targetUS[19].
Cosmic vision 2017
Small-Scale
Structure
The S2 photoelectron yield per extracted ionization
Small Experiments: Coherent Field Searches, Direct DetecIon, Nuclear and Atomic Physics, Accelerators
Microlensing
electron η is determined by studying
single-electron event
obtained during a short period of time in which the inlin
eV
keV
MeV
GeV
TeV
PeV
zeV aeV feV peV neV µeV meVargon
purification
getterwas turned
off formaintenanc
PHYSICAL REVIEWLETTERS121,
081307(2018)30M
FIG. 1: Mass ranges for dark matter and mediator purposesparticle candidates,
experimental(Fig. 2). These
runs have a anomalies,
significantly enhanced
and search techniques described in this document. All mass ranges* are merely representative; forCorresponding
author. anddetails, see the text. The QCD axion mass upper bound is set bysupernova constraints,
may be significantly raised by astrophysical uncertainties. Axion-like dark matter may also havemwada@princeton.edu
lower masses than depicted. Ultralight Dark Matter and Hidden Sector Dark Matter are broad†
frameworks. Mass ranges corresponding to various production mechanisms
within each framework
Deceased.
are shown and are discussed in Sec. II. The Beryllium-8, muon (g ‡ 2), and small-scale structure
Present
address:
North Caroanomalies are described in VII. The search techniques of Coherent Field
Searches,
DirectRaleigh,Detection,
and Accelerators are described in Secs. V, IV, and VI, respectively, andNuclear and Atomic Physics
USA.
and Microlensing searches are described in Sec. VII.
§
Present address: Carleton University, O[1] J. H. Oort, Bull. Astron. Instit. Neth. 6,
II.
SCIENCE CASE FOR A PROGRAM OF SMALL EXPERIMENTS[2] F. Zwicky, Helv. Phys. Acta 6, 110 (19Given the wide range of possible dark matter candidates, it is useful to focus the search[3]
F. Zwicky,
Astrophys. history
J. 86, 217 (1937)
for dark matter by putting it in the context of what is known
about
our cosmologicaland the interactions of the Standard Model, by posing questions
like:
What andis theJ.(particle
[4]
S.
M.
Faber
S. Gallagher, An
physics) origin of the dark matter particles’ mass? What is the (cosmological) origin of
the abundance of dark matter seen today? How do dark matterparticles
both
Astrophys.
17, interact,
135 (1979).
with one another and with the constituents of familiar
And whatother observable
FIG. 2.matter?
(Filledsymbols)
DarkSide-50(DS-50)experimenta[5]
A.
Refregier,
Annu.
Rev.
Astron.
Astrophconsequences might we expect from this physics, in addition totheexistenceofdark
matter?
Eth4electrons
N e−bespectraobtainedduringthelast
100 daysofdatataking anM
Might existing observations or theoretical puzzles
closelytied
to thephysics
of
dark
[6]
D.
Clowe,
M.
Bradač,A.
H.
Gonzalez,
MasakiKamioka
Observatory,
ICRR,
The University
Tokyo possible answers
questionshave— indeed,is onereasonwhy
FIG.
8.matter?
Ninety These
percent
upper
limitsonofmany
spin-independentDM(open symbols)
during thisthe shortperiodwhereYamashita
the getter was ofDark Sector Candidates, Anomalies, and Search Techniques
keV

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≈

zeV aeV feV peV neV µeV meV eV
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WIMPs

Ultralight Dark Ma5er

Hidden Sector Dark Ma5er

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Post-InﬂaIonary Axion

Black Holes

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Freeze-In DM
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US Cosmic vision 2017

Small-Scale Structure!!!"CLkeV

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AezeV aeV feV peV neV µeV meV eV

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10-11

10−37

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10−38
10−39
10−40
10−41

II.

SuperCDMS(2014)XMASS modulation(nuclear recoil)
XMASS modulation (2018)
DAMA NaI (2017)

_’/_

g

(ALPs)o.
FIG. 1: Mass ranges for dark matter and mediator particle candidates,
experimental
anomalies,
Dem
a
n
a
r
o
j
a
XENON100M
and search techniques described in this document. All mass ranges are merely
representative;
for
−29
10
details, see the text. The QCD axion mass upper bound is-12 set by supernova constraints, and−30
10
XMASS modulation± 1 σ expected10
mayCollarbe significantly
raised by astrophysicaluncertainties. Axion-like dark matter may also haveprev. work
−31
(2018)(Bremsstrahlung)σ expected
10lower masses than depicted. Ultralight± 2Dark
Matter and Hidden Sector
Dark Matter are broad
LUX
−32
10
frameworks.
Mass ranges corresponding to various production mechanisms within each framework
CRESST Surface(2017)−33
PandaX-II-13
10
10
are shown and are discussed in Sec. II. The Beryllium-8, muon(g2), and small-scale structure−34
this work10
anomalies are described in VII. The search techniques of Coherent Field Searches, Direct Detection,−35
10
and Accelerators are described in Secs. V, IV, and VI, respectively, and Nuclear and Atomic Physics−36
CRESST-II
10(2016)and Microlensing
searches are described in Sec. VII.
10-14

XMASS PLB 2019

DM-nucleon SI cross section [cm2]

Microlensing≈

Small Experiments: Coherent Field Searches, Direct DetecIon, Nuclear and Atomic Physics, Accelerators

10-22
10

102

(HP)

-23

SCIENCE CASE FOR A PROGRAM OF SMALL
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2m
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De [keV/c ]

a
ran
o
j
XENON100
EXPERIMENTS
Ma

10-24

LUX
Given the wide range of possible
dark matter candidates, it isuseful to focus the search(2017)
HB
-25
ork
10
for
dark matter by putting it in the context of what is known
about our cosmologicalhistory
v. w
e
−43
r
p
XENON1T
10(2018)and the interactions of the Standard
Model,by posing questions
like: What is the (particle
PandaX-II
-26
10−44
10
(2017)
physics) origin of the dark matter particles’ mass? What is the (cosmological) origin of
10−45
the
of1 dark 2matter
How do dark
matter particles interact, both2×10−1 abundance
3×10−13
4 seen5 6 7 8today?
9 10
20
10-27
this work
DM mass[GeV]with one another and with the constituentsof familiar matter? And what other observable
XMASS
PLB 2018-28
consequences might we expect from this physics, in addition
to the existence of dark
matter?
10
2
Figure 5: (Colour online) Summary of the search results. The red line is the result of the bremsstrahlung analysis for 0.32–1 GeV DM. For comparison, data from10
the CRESST
sapphire surface detector[11] and CRESST-II [33],which are searching for the elastic nuclear
recoil signals,
are shown in each colour. Thepuzzles
black line
Might
existing
observations
ortheoreticalbe closely tied to the physics
of dark2
shows the result of the nuclear recoil search at 4–20 GeV. For comparison, results from CDMS-Si [34], CDMSLite [10], SuperCDMS [35], LUX [3], XENON1T
HP
/
ALPs
mass
[keV/c]Masaki
Yamashita13
Kamioka
Observatory,
ICRR,
The
UniversityofTokyo
matter?
These
many[2], PandaX-II[4], DAMA/LIBRA [36, 37],
and XMASS-I [18],questions
DarkSide-50 [38], and the liquidhave
scintillator experiment
by Collar [39]possible
are shown for each colour. answers — indeed, this is one reason why

se
ffu
di

!

Bremsstrahlung

RG

10−42

DarkSide-50 (2018)

ETTERS 122, 131301 (2019)

Dark Sector Candidates, Anomalies, and Search Techniques
keV

MeV

GeV

TeV

30M

PeV

≈

zeV aeV feV peV neV µeV meV eV
QCD Axion

WIMPs

Ultralight Dark Ma5er

Hidden Sector Dark Ma5er

Pre-InﬂaIonary Axion

Hidden Thermal Relics / WIMPless DM

Post-InﬂaIonary Axion

Black Holes

Asymmetric DM
Freeze-In DM
SIMPs / ELDERS
Beryllium-8
Muon g-2

US Cosmic vision 2017

Small-Scale Structure
Microlensing≈

Small Experiments: Coherent Field Searches, Direct DetecIon, Nuclear and Atomic Physics, AcceleratorszeV aeV feV peV neV µeV meV eV

keV

MeV
�� �

GeV

TeV

PeV

30M

LUX

��/����� [�/��/���/��� ]��� = � ���
FIG. 1: Mass ranges for dark matter and mediator particle
candidates, experimental
anomalies,�� �
and search techniques described in this document. All mass ranges are merely representative;forσ � = �� -�� �� ����details, see the text. The QCD axion mass upper boundis set by supernova constraints, andmay be significantly raised by astrophysical uncertainties.
�� -� Axion-like dark matter may also havelower masses than depicted. Ultralight Dark Matter and
Hidden Sector Dark Matter are broad-���
AR framework
frameworks. Mass ranges corresponding to various production mechanisms within each�are shown and are discussed in Sec. II. The Beryllium-8,2), and small-scale�� muon (gn=5 structureanomalies are described in VII. The search techniques of Coherent
Field Searches, Direct Detection,
n =4
�� -�
and Accelerators are described in Secs. V, IV, and VI, respectively, and Nuclear and Atomic Physics
n =3
�� -�
and Microlensing searches are described in Sec. VII.

M. Ibe et al. 2017�� -� -�
��
II.

�� -�

�� �

�� �

SCIENCE CASE FOR A PROGRAM OF SMALL �EXPERIMENTS
��� /�����

]

�� -�
If the em
Given the wide range of possible dark matter candidates, it is useful to focus
the search=for dark matter by putting it in the context of what is known about our cosmological history the remainiDMto the groun
and the interactions of the Standard Model, by posing
is the (particle
DM questions like: WhatDM
N
physics) origin of the dark matter particles’ mass? Whatis the (cosmological)
origin of leased in theeNeN
the abundance of dark matter seen today? How do dark matter particles interact,
both The total ewith one another and with the constituents of familiar matter? And what other observable hence appro
consequences might we expect from this physics, in addition to the existence of dark matter? E is the (pnlMight existing observations or theoretical puzzles be closely
tied to the physics of dark emission.
arXiv:1711.09906v2
Masaki
Yamashita
Kamioka
Observatory,
ICRR,
The University
Tokyo possible answers
matter?
These
questionshave ofmany— Illustrationindeed, ofthis
isemission
one reason
why
FIG. 1.
electronfromnuclearre-近い将来 2020-2025
LZ Design

active mass•

10 t liquid Xenon(7 t active, 5.6 t fid.Vol.)•494 3” PMTs•

50 kV cathode•

Xenon skin detector(131 1” & 2” PMTs)•

liquid scintillator outerdetector (120 8” PMTs)

From XENON1T to XENONnT••

aume Plante - XENON

Upgrades required for XENONnT•Larger cryostat inner vessel•

New TPC•

Additional ∼200 PMTs, PMTs with lower radioactivity currently under development•

Additional DAQ electronics•

LXe

Target mass of ∼6 tons, sensitivity to spinindependent WIMP-nucleon elastic scatteringcross sections of 1.6 × 10−48 cm2

9.
(5

Dark Matter 2016 - UCLA - February 19, 2016

N
O
N
E
X 91
0
2

nT

)
n
to

4
(
)
V
n
I
o
t
X
high purity water
shield
a
7
(
d
n
Z
a
LReport, arXiv:1703.09144
Technical Design
P Lab
4850L Sanford
091
2
StatusupdatePMT
arrays
0
0
2
2

)
n
to

•

7 / 17•

12Markus Horn - LUX-ZEPLIN Dark Matter experiment

The DarkSide Collaboration: DarkSide-20k• Intermediate stage:
7• PandaX-4T (4-ton in sensitive rn)• On-site assembly andtocommiss
2018/7/24

e
d
i
S
k
r
Da 22
0
2 - June ‘19• Top & Bottom array checkouts complete

-20

9
3
k(

Yong

! M. Kapust

Fig. 3. Cross sectional view of the DarkSide-20k experiment through its center plane, showing the water tank andthe WCV detector, the stainless steel sphere and LSV detector, and the cryostat and LAr TPC.

Kamioka Observatory, ICRR, The University of Tokyo

100 t yr, accumulated during a run of approximately 5 yr, free of instrumental background, giving a sensitivity
to WIMP-nucleon interaction cross sections of 1.2 ⇥ 10 47 cm2 (1.1 ⇥ 10 46 cm2 ) for WIMPs of 1 TeV/c2(10 TeV/c2 ) mass. This is a factor of 170 improvement over the corresponding currently published limits,

Masaki Yamashita

G2実験でのチャレンジ• 大量の液体キセノン純化• neutron Veto 検出器– どちらもこのフェーズの新しいチャレンジ– DM検出感度の上げるために必要– 日本グループの貢献

Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita

27

Discussed how such a system could be integrated into XENONnT at last collaboration meeting

WIMP-nucleon Cross Section [cm2]電離電子の寿命

•

10

(
i
ns

- 43

10

10

- 44

2

ガス循環

100 SLPM

液循環

5L/min=> 2500SLPM

7 / 16

1

4

10
Electron Lifetime [µ sec]

Kai Martens, Kavli IPM

10- 47

Purity monitor
20cm drift
Kamioka Observatory, ICRR, The University of Tokyo3

2019.06.04
WIMP-nucleon Cross Section [cm2]フィルターの候補選びも順調

10c " eQcient Cu
we have an 80% – 90%

Side benefit: XENON1T LXe “fast” recovery slowness is solved

NON Collaboration Meeting - Firenze - January 12 - 14, 2018

1

- 45

10

•

1

li
pu

WIMP-nucleon Cross Section [cm2]

LXe Purification

XENONnT: Cryogenic LXe Purification

WIMP-nucleon Cross Section [cm2]

Challenge for G2(1)XENON up to 1T, XMASS, … so far→ gas phase: too slowc "
l
i
q
pu

10

kato@kamioka

- 48

10

2

1

1
10

3

4

10 28
Electrno Lifetime [µ sec]

Masaki YamashitaChallenge: neutron veto
地下実験室

• 8 neutron/20 ton-year single scatter of neutrons• TPCだけでは識別は不可能• U/Th からのfissionや (α,n) 反応

放射線シールド
材料選別

粒子弁別
on Veto( Cryostat, PMT, PTFE)• >85% neutron tagging efficiency for DM discovery.
• XENONnT (Water +Gd) (EGADS, SK-Gdの技術)• n + Gd - > total 8 MeV gamam

multiple

single-doped waterater有効体積カット
with Gd 0.2% (double of LS)
次世代 Compton
Cherenkov light from(XENONnT, LZ
s of 8 MeV gamma-ray
DS-20K) cascade
Monte Carlo
中性子vetoapturesimulations:er high light-yield volume,

Masaki Yamashita

29
29

sign

Challenge for G2(2)XENONnT

LZ
Statusupdate

反射材

Figure 4.4.2: Two steps in the assembly sequence. The figure on the left shows one of the quadrant
vessels at the point of maximum height above the water tank. The one on the right slows the four
quadrant vessels in the tank, with one already moved into final location.

te;

As a feasibility study, a mock side vessel was slung under the Yates cage, taken down the shaft, andtransported to the cart-wash area just outside the LUX experimental hall. We have studied the process of
installing the acrylic vessels into the LUX/LZ water tank using a detailed computer model. The acrylic
vessel will be transported in a horizontal position to the deck immediately above the water tank. The
vessel will then be rotated using lifting eyes at the top and bottom. The left-hand drawing in Figure 4.4.2
demonstrates one step of this process, near the point that requires maximum clearance above the deck. The
vessel is lowered in vertical position into the water tank and then transported radially outward to near thewall of the tank.
The right-hand drawing in Figure 4.4.2 shows the assembly step at which all of the quadrant vessels are in
the tank, and the first one is being brought into place around the cryostat. A white diffuse reflector, Tyvek,
is strapped with the foam around the cryostat.
The vessels will be fabricated by Reynolds Polymer Technology of Grand Junction, Colorado. Fabrication
will take place during calendar 2017.

al

4.4.2 PMT Supports
The LAB scintillation light is viewed by 120 8 inch PMTs in a cylindrical array of 20 ladders with six
PMTs each. Figure 4.4.3 shows the plan view of the PMT support system. The PMT faces are positioned
84 cm from the outer-detector tank wall. The water between the PMTs and the scintillator vessel shields theactive detector elements from radioactivity in the PMT assemblies. In this location, the PMTs also see theCherenkov light from cosmic-ray muons passing through the water.
The PMT ladders are attached to the top and bottom of the water tank, at a radius of 282 cm. The
PMT frame has been adapted from from the Daya Bay desin. A FINEMET magnetic shield to isolate the121

Water+Gd

4 side tanks at SURF inside water tank
液体シンチレータ+Gd(top & bottom tanks expected June ’1••
Kamioka Observatory, ICRR, The University of Tokyo

Gd-LS production installation at BNL
Masaki Yamashita

30

(WINO)

Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita

31

•Spin-dependent WIMP sensitivity projection (1000d)
WIMP-neutron

WIMP-proton

LZ projected WIMP sensitivity, arXiv:1802.06039
Markus Horn - LUX-ZEPLIN Dark Matter experiment

Kamioka Observatory, ICRR, The University of Tokyo

10

Masaki YamashitaDMの他には探索できる?

Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashitasuring the energy deposited in the liquid scintillator target by recoiling
electrons
undergoingneutrino–electron
elastic
scattering:
太陽ニュートリノ
nx 1 e R nx 1 e

(1)

10−2

0.8
where x denotes
oneRn of the materials
threeneutrino
flavourspp(e, m,Be t).
Total
pep The
B
Sum
ν22.
+e
detector
is Krfully described
in
ref.
pp
0.7
10
solar νν +e
Xe
1
The solar neutrino flux reachingBethe Earth 0.6
is composed not only of
10electronneutrinos produced in the nuclear reactions in the Sun, but,DARWIN
0.5
10
owing
to
the
processofflavour
oscillations(Methods),
also of muon
10
and tau neutrinos. The pp neutrino energy spectrum
extends up to
0.4
42010 keV,a maximum electron recoil energyof Emax 5 264 keV
10 yielding
ER: solar ν main BG
0.3(ref. 23). The expected flux of pp neutrinos is calculated in the frame10
0.2400500200 600
700
100 300 150
250
work0 of 0the50100
SSM200(Methods).
The
mostrecentcalculationsare
2×10
10 those
2×10
10
2×10
Energy[keV]Electronic Recoil Energy [keV]
Neutrino Energy [keV]of ref. 9 (other models, such as the one described in ref. 24, give similar
7 9
DARWIN(JCAP,
arXiv:1606.07001
Figure5.
(left)
Diﬀerential
electronrecoilspectraforpp(blue)andBe2014),
neutrinos(red) in liquid
range
results).
The
predictions
for
the
total
flux
of
pp
neutrinosatEarthgroundsolar
rate inthe1tfiducial
volume(black),andν(>1keVを観測できる。）
xenon.
Thesum contribution(solid100.2line)ppt
is split
22
21into the contributions from ⌫e (dashed) and the222
ents(purple),10 3µBq/kgofRn3(red),
of
cm
s
, for
theSurvival
high-metallicity
between5.98(1
60.006)
10other flavours (dotted). Figure adapted
from
[48].
(right)probability of solar, electron10
22
21
ouble-beta
decay(brown).
The
right
plot
shows
the
pp
neutrinocm (red)s ,isforthe together
low-metallicity
model,
and6.03(1 6 0.006)
3 10
neutrinos.
The3
expected
sensitivityof DARWIN
shown
with existing measurements
XENOnT(4ton)
1 event/day
fromTheBorexino
the: MSW
neutrino
oscillation
prediction (±1, green) for25thearelarge mixing angle
model.
latestandvaluesof ~theneutrino
oscillation
parameters
scenario [68]. The 30
precisemeasurementof the pp-flux with sub-percent precision with DARWIN will
DARWIN(FVton):~8event/dayneededtofor
calculate
the relative
proportionsof the three flavours withinallow
testing neutrino
and solar
models.
8B)
mthe
atsolarlow energies
is
not
well
known
we
~SK(
neutrino flux at Earth. For[51],reference,
when combining them
Kamioka
Observatory,
ICRR, The University
withthehigh-metallicity
SSMof Tokyo
prediction (assumed throughout thisMasaki Yamashita
−4

−5

−6

85

7

8

e

136

x

7

7

Be (862 keV)

Pee

−3

Rate [evts × t-1 × y-1 × keV-1]

ER Rate [ ( kg ⋅ day ⋅ keV ) -1 ]

222

-1

7

Be (384 keV)

-2

−7

2

3

3

4

4

34

2重ベータ崩壊
Neutrinoless Double Beta Decay
JCAP 01, 044 (2014)• 136Xeが候補

Inverted Hierarchy• 自然存在比8.8%(XENONnT,500 kg
136Xe)• 136Xe abundance in natural
xenon
8.9%
40t of Xe has 3.6t of 136Xe• ~200kg, KamLAND-Zen 400kg
e.g. EXO-200• Q-value (2458.7±0.6) keV• 高エネルギー分解能• MC assuming• T1/2 = 1.6×1025 yr (superseded)• Energy resolution (σ/μ) at Qββ 1%

136Xe  136Ba + 2e-

Q:2458 keV

T1/2DARWIN= 1.6×1025 yr

XENONnT

Kamland-Zen(PII 2016)

EXO-200(2018)
0.1 μBq/kg
T1/2 = 2.11×1021 yr

214Bi → 214Po + e– + γ (2448 keV)

実験

検出媒体

エネルギー

4.6 events/year within ±3σ

KamLAND-Zen 液 体 シ ン チ レ ー

分解能(σ)
4.7%

タ

EXO-200
XENON1T

液体キセノン
液体キセノン

1.23%

current limit (KamLAND-Zen)

T1/2 > 5.6×1026 yr (30t x yr)
T1/2 > 8.5×1027 yr (140t x yr)
Intrinsic BG only

0.9%

DARWIN (JCAP, 2014), arXiv:1606.07001)

Masaki Yamashita

35

Summary• XENONnT(2019-), LZ(2020-) , PandaX-IV(2020)• DarkSide-20k (2022)– 暗黒物質直接探索 5年でσ ~10-47 - 10-48 cm2• 広い質量領域への改善( < 1GeV)• 暗黒物質検出器 => 低バックグラウンド環境– DM– 二重ベータ崩壊、二重電子捕獲などの稀崩壊– pp太陽ニュートリノ
– 超新星ニュートリノ

Kamioka Observatory, ICRR, The University of Tokyo

Masaki Yamashita

36