Search for DM in the form of Axion-like particles ( ALPs ) and Hidden - - PowerPoint PPT Presentation

SLIDE 1

Kazufumi Sato (Nagoya Univ.) for the XMASS collaboration 10 Sep. 2019 @ TAUP2019 in Toyama

Search for DM in the form of Axion-like particles (ALPs) and Hidden Photon (HPs) in the XMASS detector

• introduction
• XMASS experiment
• search for HPs and ALPs

contents

SLIDE 2

introduction

2

SLIDE 3

ALPs & HPs

3

HP parameter space

relatively weak limits around O(10)-100 keV/c2 compared to 10 eV-10 keV

= sensitive region for

Direct DM search experiment

log10(MHP [eV])

[P. Arias et al, JCAP06(2012)013]

Hidden Photon (HP): gauge boson of hidden U(1) Axion-like particles (ALPs): pseudo-Nambu-Goldstone boson

WISPs are candidate of cold DM

• wide mass region is allowed for these bosons

1keV 100keV

SLIDE 4

principle of Direct DM search

4

• Search for the interaction of DM with a scintillating target

DM DM nucleus or e-

WIMPs with nuclear recoil (NR)

• DM + NXe → DM + NXe

PMT

various DM with e- recoil (ER)

• DM + e- → e- (+ DM)

Main physics target is WIMPs Plus, has a sensitivity for DMs causing electron recoil

XMASS experiment

target: 832 kg of liquid Xe = ~45 photon /keV ( ~ NaI)

• surrounded by PMTs

HPs and ALPs are this type

SLIDE 5

XMASS experiment

5

SLIDE 6

XMASS

6

• U of Tokyo, ICRR
• U of Tokyo, IPMU Kavli
• Kobe U. • Tohoku U.
• Tokushima U. • Tokai U.
• Yokohama National U.
• Miyagi U. of Education
• Nagoya U • Nihon U.
• IBS
• KRISS

13 institutes, ~40 participants

Direct DM search Experiment in Kamioka Observatory

• 1000 m underground under
• Mt. Ikenoyama

(= 2700 m.w.e) → shield cosmic rays

KamLAND Super-K XMASS (Lab-C) CANDLES IPMU Lab1 CLIO NEWAGE Lab2/EGad

• Tsinghua U.

SLIDE 7

Detector

7

11m 10m 80cm

Outer Detector (Water Cherenkov detector)

• veto & shield for external radiation

Inner Detector

• holds 832 kg liquid Xe
• covered by 642 PMTs
• High light yield

~ 15 p.e./keV

Low RI PMT (HAMAMATSU R10789)

SLIDE 8

Self shielding

8

inner region is kept in low BG environment!

Liquid Xe (att. L= 2.5 mm for 122 keV γ ) PMT holder surface

BG: β/γ’s from RIs in PMTs → shielded by LXe itself.

3

/(42.6 cm)

3

R

0.5 1

event rate [1/kg/day]

• 3

10

• 2

10

• 1

10 1 10

2

10

3

10

reject

RI in Xe

RI in/on

• det. comp.

n-activated Xe

Event rate VS radius (E: 40-180 keV)

R<30cm Fiducial Volume

• reconstruct the event vertex from PMT

hit pattern, and select R < 30 cm region Evt rate: ~5 × 10^-4 /day/kg/keV

SLIDE 9

Status of XMASS

9

2010 2011 2012 2013 2014 ~ 2019.3

Dec.

constr- uction

May

commissio- ning run

Nov.

refurbish- ment

continuous data taking

Al seal

identify BG source

Put Cu cover

• n the Al seal

energy [keV] events [/day/keV/kg]

Commissioning run run after refurbishment

stable operation > 5 years

SLIDE 10

Status of XMASS

10

2010 2011 2012 2013 2014 ~ 2019.3

Dec.

constr- uction

May

commissio- ning run

Nov.

refurbish- ment

continuous data taking

ALPs and HPs search

[ PLB 724 46 (2014) ]

• commissioning data
• = higher BG
• 132 days x 41 kg

today’s topic improved results with stable 2.5 yeas data

[ PLB 787 153 (2018) ]

• data after refurbishment
• 800 days × 327 kg

previous result

x 50 exposure

SLIDE 11

ALPs & HP search

11

SLIDE 12

HPs & ALPs signal

12

A0 e e γ

kinetic mixing

gAe

HP ALPs

σabsv σpe(ω = mALP )c = 3m2

ALP

16παm2

e

g2

Ae

Both bosons couple with electrons

• > absorption analogous to

photoelectric effect

HP

σabsv σpe(w = mHP )c = α0 α

cross-section of photoelectric effect

/kg/day] a event rate [1/keV

• 5

10

• 4

10

• 3

10

cor

NPE 500 1000 1500 ] a E [keV 40 50 60 70 80 90 100 110 120 mALP=50 keV/c2 70 keV/c2 90 keV/c2 110 keV/c2

➡ peak at the rest mass in E spectrum

expected E spectrum of ALPs

Event rate ∝ α’/α / mHP ∝ gAe2 × mALP

[M. Pospelov, et al., PRD 78, 115012 (2008)]

HP analogue of α

α’/α = 4 x 10^-26

10-4 10-5

[1/day/kg/keV]

10-3

SLIDE 13

peak search

13

/kg/day] a /keV

• 3

event rate [10 0.5 1

cor

NPE 500 1000 1500 2000 2500 ] a E [keV 40 60 80 100 120 140 160 180

131mXe 125I

dead tube signal

(90%CL)

RI in Xe

χ2

mHP,κ ≡ Nbin

• i
• Ri
• bs − Ri

BGtot − Ri HP(mHP, κ)

2 σ2

• bs + σ2

BGtot

+ χ2

sys,

make advance in our BG understanding → peak search by fitting the observed E spectrum with BG MC and signal MC

• m = 40 - 120 keV/c2, fit range: 30 - 180 keV

for calibration

rate of… data BG MC signal MC to deal sys. errors

fit parameter

BG rate from each RI

scan mass and α’/α (or gAe2)

• mass: every 2.5 keV, α’/α : 350 fine steps

I in Xe RBGtot =

• j:RI types

p jR j-th BG,

E spectrum in Fiducial V.

SLIDE 14

systematic errors

14

1σ uncertainty of RI amount

• RI in the detector materials
• screening by Ge detector
• analysis for the data

spectrum including high-E events in full volume

• 85Kr, daughter of 222Rn
• delayed coincident
• eg) 214Bi - 214Po in Rn chain
• RI induced by thermal neutron
• measurement for thermal

neutron flux in the mine

1σ uncertainty for MC paramters

• non-linearity of Xe light yield

ray [keV] a energy of

50 100

) a (relative to 122.1 keV Data/MC of NPE

0.5 0.6 0.7 0.8 0.9 1

57Co 241Am

non-lineartiy from source calibration

• Energy resolution
• position resolution
• mis-reconstruction events

due to dead PMTs

χ2

sys = j14C,39Ar

• j:RI types

1 − p j δp j 2 +

• m

∆Cm δCm 2 ,

pj, ΔCm : fit parameters

SLIDE 15

]

2

ALPs mass [keV/c

2

10

Ae

g

• 14

10

• 13

10

• 12

10

• 11

10

]

2

HP / ALPs mass [keV/c

2

10

_ ’/ _

• 28

10

• 27

10

• 26

10

• 25

10

• 24

10

• 23

10

• 22

10

this work

• prev. work
• prev. work

this work

M a j

• r

a n a D e m

• .

XENON100 XENON100 Majorana Demo. LUX PandaX-II diffuse ! R G HB

(ALPs) (HP)

Result

15

• cover higher mass region

than LUX, PandaX

☜ ☜

best limit in 40-120 keV/c2

• cover a region where the

limits from indirect searches is relatively weak.

• The limit improves by factor

10~50 from our previous work

[light blue: H. An et al., PLB 747 331(2015)]

didn’t find any finite peak

• > set 90%CL upper limit

10-27 10-26 10-25 10-24 10-13 10-12 gAe α’/α

SLIDE 16

Summary

16

• XMASS : direct DM search using ~800 kg liquid Xe
• low BG environment including ER events.
• sensitive for electron-scattering DM like HPs and ALPs
• >5 years stable operation
• search for Axion-like particles and Hidden Photons
• direct detection through absorption analogue to

photoelectric effect

• several improvement from the previous measurement
• increase in exposure by × 50
• improved BG understanding

→ enable to fit the observed E spectrum by MC

• set upper limit on α’/α of HP and gAe of ALPs
• present the best limits in 40 < mass < 120 keV/c2

SLIDE 17

backup

17

SLIDE 18

Detector

18

11m 10m 80cm

Outer Detector (Water Cherenkov detector)

• 10-m Φ ×11 m height
• 72 20-inch PMTs
• Active veto for cosmi. μ
• Passive shield for

external neutrons & γ’s OFHC Copper vessel

• hold liquid xenon
• vacuum insulation
• keep at ~100℃

Inner Detector

SLIDE 19

cont.

19

Inner Detector (Liquid Xenon detector)

• 832 kg LXe sensitive

volume

• sphere of 80 cm in dia.
• 642 2-inch PMTs
• high QE: 28~39%
• photo. coverage > 62%
• High light yield:
• ~15 p.e / keV
• low RI

spread over the inner surface

238U chain

1.2

232Th chain

< 0.78

40K

9.1

60Co

2.8 [mBq/PMT]

HAMAMATSU R10789

80 cm

SLIDE 20

physics results

20

2010 2011 2012 2013 2014 2015 2016

Dec.

constr- uction

May

commissio- ning run

Nov.

refurbish- ment

continuous data taking

bosonic super WIMPs PLB 724 46 (2014) low mass WIMP PLB 719 78 (2013) solar axion PLB 724 46 (2013)

Inelastic WIMP scattering PTEP 063C01 (2014) 2νECEC PLB 759 272 (2016)

Solar KK axion PTEP 103C01 (2017) WIMP annual modulation PLB 759 64 (2016) PRD 97 102006 (2018) WIMP search in fiducial volume arXiv:1804.02180(2018) 2νECEC PTEP 053D03 (2018)

10-47 10-46 10-45 10-44 10-43 10-42 10-41 10-40 10-39 101 102 103 104 WIMP-nucleon cross section [cm2] WIMP mass [GeV/c2] XMASS (2013) XMASS mod. (2017) S u p e r C D M S D E A P 3 6 D a r k S i d e

• 5

( 2 1 8 ) P a n d a X

• I

I ( 2 1 7 ) LUX (2017) XENON1T (2017) This work DAMA/LIBRA (Na) CoGeNT (2013) CDMS-Si (2014)

XMASS FV (2018)

limits on WIMP cross section

WIMPs with NR

• ther DM with ER
• ther physics

XMASS mod.

Inelastic WIMP scattering XXXXXX (2019) sub-GeV DM XXXXXX (2019)

ALPs and HPs PLB 787 153 (2018)

SLIDE 21

low BG environment

21

LUX-ZEPLIN (Xe 5.6 Tonne Fid.)! pp solar dominates

avid Malling, Brown, for preparing slide

XMASS%I

event rate including ER events

3

/(42.6 cm)

3

R

0.5 1

event rate [1/kg/day]

• 3

10

• 2

10

• 1

10 1 10

2

10

3

10

reject

RI in Xe

RI in/on

• det. comp.

n-activated Xe

Event rate VS radius

(40-180 keV E deposit)

Original figure taken from D.C. Malling, Ph.D(2014) Fig1.5

R<30cm event rate is ~5 × 10^-4 /day/kg/keV ( inside fiducial volume, at E = 10s ~ 100 keV )

10 100 1000 E[keV] 10 1 10-2 10-4 10-6

event rate [1/day/kg/keV]

SLIDE 22

property of xenon

22

condition atomic mass 131.3 boiling point

• 108 ℃

@ 1 atm density 2.95 g/cm3 @ -111℃ wave length 174.8 ± 0.1 nm

• scat. length

30-60 cm for scintillation light absorption length > 1 m LY ~46 photon/keV for 1 MeV e- decay time < ~45 ns for electron

SLIDE 23

single- / double-phase detector

23

e- recoil nuclear recoil

log10(S2/S1)

WIMP

S1 nucleus

WIMP

single phase

[XENON100, PRL 105, 131302 (2010)]

double phase (liquid + gas)

における背景事象

field shaping ring

XENON10/100タイプ

Liquid Xe Gas Xe

PMT array

PMT array

gate anode

cathode

shield PTFE

いくつかの 源が議論されている

放射線 より 桁高い

ガス層での事象 間でガ ス増幅が起こり が発生 中の不純物

を下げられない原因

による光電効果 の発光 検出器部材の仕事関数

WIMP WIMP

S1 nucleus S2

→ operated as TPC

drift e-

SLIDE 24

refurbishment

24

SLIDE 25

refrigerator

purification system

GXe LXe

Xe purification

25

• b

t

• 4m

Distillation tower

Xe itself has (almost) no RI. main RIs in xenon are…

• 85Kr (T1/2 = 10.8 years) :
• exist from the beginning in

commercial Xe gas

• 222Rn (T1/2 = 3.82 days ) :
• daughter of U-chain
• emanated from det. comp.

Kr LXe intake LXe

• utlet

GKr

• utlet

Kr

remove 85Kr

Xe BP: ~175 K ⇆ Kr BP: ~150 K

remove 222Rn with activated charcoal

XMASS, Astopart. Phys. 31, P290 (2009)

XMASS, NIM A661, P50 (2012)

Distillaiton touwer absorber

SLIDE 26

delayed coincident

26

100#us#<#dT <#1000#us dTpre >#100#us

Bi# candidate#(!+") Po candidate#(#)

removed#by#pre<selection

FADC%window%(,1,%+9%µs)

! candidate (Q!,=173keV) " candidate (514%keV)

Dead%time (+9,%+15%µs) Trigger%timing Trigger%timing (next%event) sumWF (,200,%+300ns) sumWF (,200,%+300ns)

222Rn (use 214Bi-214Po chain) 85Kr (use β-γ rays chain)

222Rn

8.53 ± 0.16 mBq / detector 0.25 ± 0.04 mBq / detector

SLIDE 27

27

Location of RI RI Activity [mBq/detector] Activity [mBq/detector] initial value of the fit the best fit value LXe

222Rn

• 8.53±0.16

85Kr

• 0.25±0.04

39Ar

• 0.65±0.04

14C

• 0.19±0.01

copper plate and ring

210Pb

• (6.0±1.0)×102

copper surface

210Pb

• 0.7±0.1

PMT quartz surface

210Pb

• 6.4±0.1

PMT

238U

(1.5±0.2)×103 (2.0±0.2)×103 (except aluminum seal

232Th

(1.2±0.2)×103 (1.1±0.3)×103 and quartz surface)

60Co

(1.9±0.1)×103 (1.6±0.2)×103

40K

(5.8±1.4)×103 (9.6±1.7)×103

210Pb

(1.3±0.6)×105 (2.2±0.7)×105 PMT aluminum seal

238U

(1.5±0.4)×103 (9.0±4.1)×102

235U

(6.8±1.8)×101 (4.1±1.8)×101

232Th

(9.6±1.8)×101 (5.5±2.2)×101

210Pb

(2.9±1.2)×103 (3.4±1.2)×103 Detector vessel,

238U

(1.8±0.7)×103 (9.0±7.6)×102 holder and filler

232Th

(6.4±0.7)×103 (6.4±3.2)×103

60Co

(2.3±0.1)×102 (3.0±1.9)×102

210Pb

• (3.8±0.5)×104

SLIDE 28

125I peak @ 67.5 keV

28

Gas Xe outside the water sheild captures thermal neutron

124Xe -> 125Xe -> 125I

neutron capture decay

getter

Liquid*xenon

Cable*field*box Cooling*tower detector Carib.*system

flux = 1.1 x 10-5 /cm2/s

thermal neutron in the mine → go inside the detector through cooling port

peak @ 67.3 keV

SLIDE 29

calibration

29

Stepping motor Magnetic*linear*and* rotary*motion feedNthrough Top PMT

~5m

Gate*valve

r. &

Tank&top

Water&tank

10

• the topmost PMT is removable by
• peration from outside
• rod with needle-shaped RI source is

inserted into the detector

• once / 2weeks with 57Co (122 keV γ)
• to monitor …
• light yield
• absorption length
• scattering length

RI#source#with#rod

SLIDE 30

Sys errors

30

⊕

ID (energy of γ-rays or events used to derive the correction) (≡ m) kind of correction correction factor and its error (≡ Cm ± δCm) m = 1 non-linearity of Xe scintillation ( 5.9 keV) ( 17.8 keV) ( 30 keV) ( 59.3 keV) ( 59.5 keV) Data

MC relative to 122.1 keV

• 80+5

−5%

79+3

−4%

91+3

−3%

91+3

−3%

94+3

−3%

m = 2 NPEcor resolution ( 59.3 keV) ( 122.1 keV) (δE/E)2

data − (δE/E)2 MC

• 3.8 ± 2.0%

1.1 ± 0.4% m = 3 Rrec resolution ( 59.3 keV) ( 122.1 keV) (δRrec)2

data − (δRrec)2 MC

• 2.5 ± 1.1 mm

1.3 ± 0.3 mm m = 4 event increase due to dead PMTs (441 < NPEcor < 515) (Data/MC − 1) (7 ± 14)% m = 5 event increase due to dead PMTs (515 ≤ NPEcor < 588) (Data/MC − 1) (19 ± 16)%

SLIDE 31

mis-reconstruction due to surface BG

PMT PMT reconstructed R for surface BG(MC) R [cm]

SLIDE 32

Dead tube

32

distribution of low E event

(2D Mollweide projection)

SLIDE 33

σp.e.

33

SLIDE 34

xenon as γ shield

34

xenon attenuation length for γ ray [cm2/g] gamma energy [keV] 1 10 100 1000 1 100 10000 0.01 ~2.5mm for 122 keV γ ~6 cm for 1 MeV γ

SLIDE 35

35

α’/α χ2

90%CL

scan the parameter space

• fitting was done
• for every 2.5 keV mass
• and, for each fine step of α’/α

mHP=XXX keV

• > get the profile curve

R α0/α90 exp

• −χ2/2
• d (α0/α)

R 1 exp (−χ2/2) d (α0/α)

SLIDE 36

cont.

36

[keV]

electron

E

1 10

2

10

3

10

[ns]

2

τ

25 30 35 40 45 50

This work . et al Akimov Ueshima . et al Teymourian . et al Dawson . et al Keto

[ XMASS NIM A834 (2016) 192 ]

time constant of Xe scintillaiton has a dependence on E of β-ray

!! 214Bi'data !! 214Bi'MC

!! 241Am'60keV'data !! 241Am'60keV'MC

!!ray'like

β rejection for double β decay

[ ref) TAUP2017 Hiraide’s slide]

電子らしさ を計算

γ-ray converted several small-E β-rays

ex) 59.5 keV γ → 25 keV e+ 30keV X-ray + Auger electrons

⇨ <Eelectron> = 27.2 keV

⇆ shorter time constant than 59.5 keV e-

→S/N ×~5

(Edep~60keV)