電子散乱事象の超過@XENON1T実験
風間慎吾 (名古屋大学 KMI & 高等研究院)@ダークマター懇談会2020

暗黒物質の直接探索

2

WIMPの探索方法(直接探索)

確率は非常に小さいがWIMPも身の回りの物質(原子核)と相互作用をする(原子核反跳)。
原子核が受け取る反跳エネルギーを検出する(光 & 電子 for XENON1T実験)。

XENON1T実験のWIMP探索結果

XENON1T実験• 液体キセノンを3.2トン(有効体積~1トン)を用いた直接探索実験• 低質量&高質量の両極限(100MeV - TeV)で、世界で最も厳しい制限を与えている。
• 実験自体は既に終了していて、現在XENONnT実験へとアップグレード中(小林くんのトーク)

暗黒物質の直接探索

3

太陽アクシオンや太陽ニュートリノの探索方法: 電子反跳
太陽アクシオン: Axio-electric eﬀect (光電効果と似た効果, gae)
太陽ニュートリノ: 電子散乱 (elastic scattering )WIMPと原子核の相互作用 (原子核反跳)

e

gae e
<latexit sha1_base64="IX9cE8LYzUnKEJBcdKKQl9h5f6E=">AAAB7XicdVDLSgNBEJz1GeMr6tHLYBA8LbMxmM0t6MVjBPOAZAmzk04yZnZnmZkVwpJ/8OJBEa/+jzf/xslDUNGChqKqm+6uMBFcG0I+nJXVtfWNzdxWfntnd2+/cHDY1DJVDBpMCqnaIdUgeAwNw42AdqKARqGAVji+mvmte1Cay/jWTBIIIjqM+YAzaqzUHPYyCtNeoUjcykWpWvUwcf0yIcS3pEp8v+xjzyVzFNES9V7hvduXLI0gNkxQrTseSUyQUWU4EzDNd1MNCWVjOoSOpTGNQAfZ/NopPrVKHw+kshUbPFe/T2Q00noShbYzomakf3sz8S+vk5qBH2Q8TlIDMVssGqQCG4lnr+M+V8CMmFhCmeL2VsxGVFFmbEB5G8LXp/h/0iy53rlbuikXa5fLOHLoGJ2gM+ShCqqha1RHDcTQHXpAT+jZkc6j8+K8LlpXnOXMEfoB5+0TREOPmQ==</latexit>a

太陽アクシオン・太陽ニュートリノ (今回はこちら！)

電子反跳事象の探索• 通常、電子反跳事象はWIMP探索の背景事象(BG)• WIMP searchと比べてBG量(ex: 放射性ラドン・クリプトンなど)が多いので、BGをより精密に評価し、そこからの超過を探す

4

LXe TPC: Working Principle- Primary scintillation light (S1) is produced promptly at theinteraction site

Particle Detection Principle with a Dual-phase TPC

electronic recoils-(ER)Ionization electrons drift up through the LXe in the applied

γ or e–electric ﬁeld

WIMPs
or neutrons

Matter Detection XewithnuclearLXe
recoils (NR) TPCs
- Some recombine with ions ̶> more scintillation light (S1)
~8kV/cm· Two signal channels (S1 and S2)

drift time → Z coordinate

m

ic

m

ot
io

escapeNex

de-excitatione- drift,
accelerationin gas phase

scintillation
(S1)

n

heat

proportional

ionization

recombination

excitation

E0 atoEnergyregion, where they form secondary proportional scintillation- S1 area· Ratio depends on dE/dx, different probability for light (S2)
~0.1kV/cm- S2 area
electron-ion pairs recombinationv(drift) ~ 1.3 mm/us
Position- Event vertex reconstruction
in 3D
space
x-y
(S2
signal)➝ event vertex reconstruction in 3D- X,Y position: S2 hit-patternintime)top PMT arrayz(drift(~mm precision for Z, ~cm for XY)- Z position: electron
drift time,
Interaction
typeΔt (s1, s2 )- S2/S1 ratio (ER/NR)
1m
Particle type discrimination: (S2/S1)γ,e > (S2/S1)WIMP➝ particle type discrimination: (S2/S1)γ > (S2/S1)- WIMP(factor ~ 200 and higher efficiency)
Electric Recoil
Nuclear Recoil

scintillation(S2)

S2(電子信号) [PE]

io

ti
za
i
n

on

Ni

- Others are extracted above the liquid surface into gas phase

Electric Recoil
Nuclear Recoil
S1(光信号) [PE]7

XENON1T WIMP Searches - 2018 (NR Search)
One ton-year of search for WIMPs induced nuclear recoils

threshold: ~5 keVnr

Most stringent result on WIMP Dark Matter down to 3 GeV/c2 masses

5

XENON1T Solar-Axion / ALPs Searches - 2020 (ER Search)
検出器部材からの放射線(ガンマ線)を除くため、有効体積はWIMPより小さい。

threshold: ~1 keVee

太陽アクシオンやALPs, Dark Photon探索における戦略-

電子反跳BGの絶対量を減らす

既知のBG(放射性ラドン・クリプトンなど)を精密に評価し、超過を探す6• 1st ton-scale experimentfor direct DM detection.
• 3.2t of LXe, 2t in TPC.
• 20x larger than Xe100.
• Constructed @LNGS.
• Commissioning sincesummer.
• Data taking has started.
• Expected sensitivity
1.6E-47 cm2
at mWIMP = 50 GeV
for 2 ton years exposure.

XENON1T Detector
H. Simgen - MPIK: "XENON1T", TPC 2016 / Paris

The XENON Project + DARWIN

The XENON + DARWIN Program

anuary 27th, 2020, LLR

8

先週ちょうど液体キセノンをﬁllし始めた！
17

Luca Scotto Lavina, CNRS/IN2P3

名大、神戸大、IPMUは先月末にDARWINにも参加！

-handling system (see figure 9) and allows the insertion of short-lived isotopes for calibration. Some instrumentation suchssure sensors, as well as several access ports are omitted for clarity. The path of the xenon gas during standard purification

The XENON1T Experiment @ LNGS in Italy9

Puriﬁcation (H2O/O2)とKr distillationにだけフォーカス
して紹介

Water tank: ~700 ton

248
3-inchthe
PMTs(R11410-21,
QE~34%@178nm)
ng system of XENON1T consists of the cryogenic system(cooling),
purification
system (online
removal of electronegayogenic distillation column (nat Kr removal), ReStoX (LXe storage,
fillingand recovery),the gas2.0t
bottle(active)
rack (injection of gas
LXe
mass:
3.2 t(total),p of XENON1T (not to scale). The colors indicate different sub-components and are also used in Fig. 2, which shows theirs to the overall 222 Rn rate.

GXe Purification

10

E. Aprile and T. Doke: Liquid xenon detectors for particle physics …

2066

S1光の吸収

0.5
0.45
0.4

Ozone, 2005

1 ppm

0.35

L ef f

0.3
0.25
0.2
0.15

1 ppm

0.1
0.05

FIG. 25. !Color online" Absorption coefficient for vuv pho‣ Electronegative0
impurities in1 the Xe gas and from outgassing
reduce2
1010
in 1 ppm water vapor and oxygen and superimposed Xe eboth photon (S1) and electron(S2)Energy
signals.
NuclearRecoil[keV]
222
ub-system contributions to the overall Rn emanation rate in XENON1T. The colors correspond to those used in Fig. 1.
sion spectrum !Ozone, 2005".

ackets refer to the item numbers.

24.light!Coloronline"efficiently,
Relative scintillation
efficiency
of‣ To FIG.
detectS1 signals
need O(1) ppb
H2O concentration.
nuclearrecoils
in LXeal., for2009,
and measurement)
references(TigerOptics
HALO+
H2O !Aprilemonitoretused
puritytherefore considered this to be the main mechanism
therein".

sponsible for the reduction of the total scintillation yin LXe under irradiation by nuclear recoils. The Hita
‣ To drift electrons over 1 meter requires < 1ppb (O2 equivalent)ticles. Knowledge of the ratio between the twomodel !Hitachi et al., 1992, 2005", however, does
scintillation yields, called relative scintillation efficiency
hold at energies below 10 keVr.
‣ Solution:
continuous
at high flow
throughheated getter!Leff", isimportantgas
forcirculation
the determinationof thesensitivmaterial
getter,
400 C)towithhydrogenremovalinterunit
ity of (Zr-V-Fe
LXe-based
detectors
darkmatter weakly
5. Absorption length and Rayleigh scattering
acting massive particles !WIMPs", which we discuss in‣ SAES
H2O, CO,recoils
CO2, H2,
N2, CH4:
Impurities dissolved in LXe may absorb the vuv p
Sec.PS4-MT50-R
IV.B. The (O2,
Xe nuclear
which
result~ppb)
fromtons, reducing the observed scintillation light yi
WIMPs !or neutrons" scattering off Xe nuclei have enLight attenuation can be described byergiestheofrangeof adriven
few keVseveral tens of‣ Totalflowinrate
54 slpmby upupto to
3 pumps.

line at 32.1 keV from metastable 83m Kr, which is very welldescribed by an exponential function.
Figure 19 shows the electron lifetime evolution overa period of approximately two months, during science

GXe Purification

11

S2 [PE]

10
20000
700
600

15000

500
400

10000

300
5000

200

Fit with exp(-Δt/τ)
100

200

300

400

100
500

0

600

Drift Time [µs]Fig. 18 The loss of electrons due to the presence of electronegative impurities in the LXe is measured via the drift time-dependent decreaseof the charge signal size, e.g., from the mono-energetic 32.1 keV linefrom 83m Kr. The example shown here corresponds to an electron lifetime te = (467 ± 5) µs, derived from the exponential fit (red line).

FIG. 9: Electron lifetime evolution during the two science runs measured from 83m Kr (black), 222 Rn (red) and 218 Po (green)
decays. Decreases are caused by releases of impurities due to changes in detector operation parameters like the detector’s coolingpower and the gas flow in the purification system. The temporal fine structure is modeled based on the ↵ measurements (greyline) while the absolute scale of the electron lifetime is determined from the 83m Kr measurement.

Electron Lifetime [µs]‣ 550
Solution: continuous gas circulation at high flow through heatedgetter material (Zirconium)
500
450

‣ 400
SAES PS4-MT50-R (O2, H2O, CO, CO2, H2, N2, CH4: ~ppb)
350

‣ Nov
Total
flow rateof 54 slpmJandriven
by up
to 3 pumps.
16
Dec 0901
Jan 23
Date

Fig. 19 Evolution of the electron lifetime over science run 0, which
650usof verticale-lifetime
̶>equivalentis‣indicatedby thelines. The
two oxygen
step-like decreases
are well- impurity concentration
understoodand related to detector operation (e.g., online 222 Rn distilof ~ 0.5ppb.
lation which started on December 19). The model (red line) describes
FIG. 10: Spatial dependence of the relative light collection efficiency Lc on z (left) andthe data well.
code). Data points are connected by straight lines to guide the eye.

(right) for di↵erent radial bins (color‣ XENON1T TPC length ~ 650us drift time

In order to correct for the spatial dependence of S1
signals, a three-dimensional correction map is derived
from the 32.1 keV signals in 83m Kr calibration data. The
mean of the S1 distribution is evaluated in discrete (R,)-regions and in slices of z, and is normalized to its

dependence of ✏L but also accounts for the spatiallydependent P Y introduced by field inhomogenities.
83m
Kr decay energies lie beyond the region of interest
for WIMP searches and lower energetic events are lesssensitive to changes in the field. Hence, a small bias of

by g spectrometry, it must be measured independently sincein most cases emanation is dominated by surface impurities. tion efficiency can be monitored using the short-lived iso83m Kr as a tracer [53, 54]. After installation at LNGS,
tope
12
The measurements were performed according to the proce+1.9
5 was measured [52,222aseparation
factor
of
(6.4
)
⇥
10
describedXe:in 1[49]
using
Rn
1.4
Commercialppm- 10theppb natKr,emanation facility at▸ durenat
55],
reachingaconcentration
Kr/Xe < 0.026 ppt and
MPIK
Heidelberg
[50]
and
a
similar
one
at
LNGS.
The
re▸ 85Kr is unstable (T1/2 = 10.8 y, β-decay with Q-value = 687 keV)higher Kr/Ar lower T
sults are summarized in [51].
▸ Solution: 5.5 m cryogenic distillation column
To remove radioactive isotopes from surfaces, all TPC
Off-gasUtilizes diﬀerent▸ components
were vaporcleanedpressure:
after production according to the(high Kr)
- Kr: 20900
followingprocedures:
after Xe:
degreasing,all copper pieces
mbar@178K,
2010 mbar@178K
Top
condenser
were
pickledinasolution
of
1%
H
SO
and
3%
H
O
2
4
2
2
Feeding
ﬂow
rate:
8.3
SLPM
(3kg/h)▸Liquidand passivated in a 1% citric acid (C6 H8 O7 ) solution. Af- Thermodynamically stable up to 18 SLPM (6.5 kg/h)
Package tube
terwards the pieces were rinsed with de-ionized water and5▸ ethanol.
Measured
6.4 10 @8.3
SLPM,
< 48
ppqTPC(RGMS)
Theseparation:
large stainless-steel
pieces(divingbell,
5.5m Gas outlet
electrodeframes)were
electropolishedandcleanedwith
5.5m
Kr dominated
Rn dominated(low Kr)
acetone, de-ionized~1000water
ppt and ethanol. All small stainlesssteel components (screws, rods, etc.) were degreased, pickGas inlet
led in a solution of both 20% HNO3 and 2% HF, and finallyGaspassivated in a 15% HNO3 solution before rinsing with deHeat exchanger
ionized water and ethanol. The degreased PTFE components
Input condenser
were immersed in a 5% HNO3 solution and rinsed with deionized water and ethanol. Care was taken to not touch theReboilerreflecting TPC surfaces during cleaning, and all PTFE parts
puriﬁed Xe higher T
were stored under vacuum after the cleaning procedure. In Fig. 11 The custom-designed XENON1T cryogenic distillation colcases of size limitations, the HNO3 -step was omitted and~theumn. The outer vessels for vacuum insulation and most of the column
0.66ppt
package material were omitted for clarity.
sample was instead immersed in ethanol for a few hours.

Kr (and Ar) Distillation

85

222

Energy Reconstruction

Energy Reconstruction with LXe TPC
S1 S2
E = (Nph + Ne ) · W = (
+
)·W
g1
g2
<latexit sha1_base64="d6IcuMqTVy/aBIabuKEG5iEtPeM=">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</latexit>

where W = 13.7 eV/quanta

g1 and g2: detector-speciﬁc gain constants
extract g1/g2 from calibration data, use it toreconstruct energy of each event

14

S1, S2はPMTで測定される量!

S1
/ nph
<latexit sha1_base64="I+WtHbz3tmGrDshBRDeMZK46pMs=">AAAB9XicdVBNSwMxEJ31s9avqkcvwSJ4KrtVcb0VvXisYD+gXUs2zbah2WxIskpZ+j+8eFDEq//Fm//GtF1BRR8MPN6bYWZeKDnTxnU/nIXFpeWV1cJacX1jc2u7tLPb1EmqCG2QhCeqHWJNORO0YZjhtC0VxXHIaSscXU791h1VmiXixowlDWI8ECxiBBsr3XalSqRJkOhlcjjplcpuxZ0BWXLu+37VEs+vnro+8nKrDDnqvdJ7t5+QNKbCEI617niuNEGGlWGE00mxm2oqMRnhAe1YKnBMdZDNrp6gQ6v0UZQoW8Kgmfp9IsOx1uM4tJ0xNkP925uKf3md1ER+kDEhU0MFmS+KUo7sn9MIUJ8pSgwfW4KJYvZWRIZYYWJsUEUbwten6H/SrFa840r1+qRcu8jjKMA+HMAReHAGNbiCOjSAgIIHeIJn5955dF6c13nrgpPP7MEPOG+fPk2TAg==</latexit>

S2/ ne<latexit sha1_base64="798E/ml8/AhDrg4V6USVIu0t2/Q=">AAAB9HicdVBNSwMxEJ31s9avqkcvwSJ4KrtVcb0VvXisYD+gXUo2zbah2WRNsoWy9Hd48aCIV3+MN/+NabuCij4YeLw3w8y8MOFMG9f9cJaWV1bX1gsbxc2t7Z3d0t5+U8tUEdogkkvVDrGmnAnaMMxw2k4UxXHIaSscXc/81pgqzaS4M5OEBjEeCBYxgo2Vgm6iZGIkEr2MTnulsltx50CWXPq+X7XE86vnro+83CpDjnqv9N7tS5LGVBjCsdYdz01MkGFlGOF0WuymmiaYjPCAdiwVOKY6yOZHT9GxVfooksqWMGiufp/IcKz1JA5tZ4zNUP/2ZuJfXic1kR9kTCSpoYIsFkUpR/bNWQKozxQlhk8swUQxeysiQ6wwMTanog3h61P0P2lWK95ppXp7Vq5d5XEU4BCO4AQ8uIAa3EAdGkDgHh7gCZ6dsfPovDivi9YlJ585gB9w3j4BZauShQ==</latexit>

Energy Reconstruction with LXe TPC

15

S1 S2
E = (Nph + Ne ) · W = (
+
)·W
g1
g2
<latexit sha1_base64="d6IcuMqTVy/aBIabuKEG5iEtPeM=">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</latexit>

where W = 13.7 eV/quanta

g1 and g2: detector-speciﬁc gain constants
extract g1/g2 from calibration data, use it toreconstruct energy of each event

E=W<latexit sha1_base64="R/1AE251QmRnw0/RhTrqHxWgkrc=">AAACG3icdZDLSgMxFIYz3q23qks3wSIoQslMLdaFIIrgsqK1QqeUTJppQzMXkjNCGeY93Pgqblwo4kpw4duYqRVU9EDg5/vP4eT8XiyFBkLerYnJqemZ2bn5wsLi0vJKcXXtSkeJYrzBIhmpa49qLkXIGyBA8utYcRp4kje9wUnuN2+40iIKL2EY83ZAe6HwBaNgUKfonOJD3MSu5D5su76iLL2ws7TXsTO8i8fAyYGTuUr0+rDTKZZImZBKhVSxEQe1apUYYdccm1Swbay8Smhc9U7x1e1GLAl4CExSrVs2iaGdUgWCSZ4V3ETzmLIB7fGWkSENuG6no9syvGVIF/uRMi8EPKLfJ1IaaD0MPNMZUOjr314O//JaCfi1dirCOAEess9FfiIxRDgPCneF4gzk0AjKlDB/xaxPTR5g4iyYEL4uxf+LK6dsV8rO+V7p6HgcxxzaQJtoG9loHx2hM1RHDcTQLbpHj+jJurMerGfr5bN1whrPrKMfZb19AMhmoBY=</latexit>

✓

S1 S2
+
g1
g2

◆

220Rn calibration data

220Rn calibration data

2D analysis in s1-s2 space

1D energy spectrum

Signal Models

Data Selection & Efficiency
Feb. 2017

Science Run 1(SR1)

226.9 days

Feb. 201817• Fiducial volume 1042 kg• Single-scatter events, standard data
quality cuts
• Higher S2 threshold (> 500 pe) toremove instrumental BGs• Detection eﬃciency is dominated by
3-fold PMT coincidence for S1
detecetion

Energy region of interest:
1 - 210 keVee
Eﬃciency for ~2 keVee is ~ 70%Solar-Axion: Production

18

Three components of solar axion flux
ABC

(Atomic recombination anddeexcitation, Bremsstrahlung
and Compton)

axion-electron interactions
dominated by Bremsstrahlung and Compton

Primako!:egae e<latexit sha1_base64="IX9cE8LYzUnKEJBcdKKQl9h5f6E=">AAAB7XicdVDLSgNBEJz1GeMr6tHLYBA8LbMxmM0t6MVjBPOAZAmzk04yZnZnmZkVwpJ/8OJBEa/+jzf/xslDUNGChqKqm+6uMBFcG0I+nJXVtfWNzdxWfntnd2+/cHDY1DJVDBpMCqnaIdUgeAwNw42AdqKARqGAVji+mvmte1Cay/jWTBIIIjqM+YAzaqzUHPYyCtNeoUjcykWpWvUwcf0yIcS3pEp8v+xjzyVzFNES9V7hvduXLI0gNkxQrTseSUyQUWU4EzDNd1MNCWVjOoSOpTGNQAfZ/NopPrVKHw+kshUbPFe/T2Q00noShbYzomakf3sz8S+vk5qBH2Q8TlIDMVssGqQCG4lnr+M+V8CMmFhCmeL2VsxGVFFmbEB5G8LXp/h/0iy53rlbuikXa5fLOHLoGJ2gM+ShCqqha1RHDcTQHXpAT+jZkc6j8+K8LlpXnOXMEfoB5+0TREOPmQ==</latexit>a<latexit sha1_base64="emqY+BI9DAkA8j0Anp1oEGgvCRw=">AAAB7XicdVDLSgNBEOz1GeMr6tHLYBA8LbMxmM0t6MVjBPOAZAmzk0kyZnZ2mZkVwpJ/8OJBEa/+jzf/xslDUNGChqKqm+6uMBFcG4w/nJXVtfWNzdxWfntnd2+/cHDY1HGqKGvQWMSqHRLNBJesYbgRrJ0oRqJQsFY4vpr5rXumNI/lrZkkLIjIUPIBp8RYqTnsZUROe4UidisXpWrVQ9j1yxhj35Iq9v2yjzwXz1GEJeq9wnu3H9M0YtJQQbTueDgxQUaU4VSwab6bapYQOiZD1rFUkojpIJtfO0WnVumjQaxsSYPm6veJjERaT6LQdkbEjPRvbyb+5XVSM/CDjMskNUzSxaJBKpCJ0ex11OeKUSMmlhCquL0V0RFRhBobUN6G8PUp+p80S6537pZuysXa5TKOHBzDCZyBBxWowTXUoQEU7uABnuDZiZ1H58V5XbSuOMuZI/gB5+0TUfCPog==</latexit>a<latexit sha1_base64="I0zVRlzAmaf+N8fGMnkfim9z4HY=">AAAB7XicdVDLSgMxFM34rPVVdekmWARXQ6YWO90V3bisYB/QDiWTpm1sHkOSEcrQf3DjQhG3/o87/8b0IajogQuHc+7l3nvihDNjEfrwVlbX1jc2c1v57Z3dvf3CwWHTqFQT2iCKK92OsaGcSdqwzHLaTjTFIua0FY+vZn7rnmrDlLy1k4RGAg8lGzCCrZOa3SEWAvcKReRXLkrVagCRH5YRQqEjVRSG5RAGPpqjCJao9wrv3b4iqaDSEo6N6QQosVGGtWWE02m+mxqaYDLGQ9pxVGJBTZTNr53CU6f04UBpV9LCufp9IsPCmImIXafAdmR+ezPxL6+T2kEYZUwmqaWSLBYNUg6tgrPXYZ9pSiyfOIKJZu5WSEZYY2JdQHkXwten8H/SLPnBuV+6KRdrl8s4cuAYnIAzEIAKqIFrUAcNQMAdeABP4NlT3qP34r0uWle85cwR+AHv7RML6o90</latexit>

gan

n

n

a

ga
<latexit sha1_base64="em+BPcVBUTG2CuB/mi346DAW0UI=">AAAB8nicdVDLSgNBEJyNrxhfUY9eBoPgaZmNwWxuQS8eI5gHbELonUySITO7y8ysEJZ8hhcPinj1a7z5N04egooWNBRV3XR3hYng2hDy4eTW1jc2t/LbhZ3dvf2D4uFRS8epoqxJYxGrTgiaCR6xpuFGsE6iGMhQsHY4uZ777XumNI+jOzNNWE/CKOJDTsFYKRj1M+iOQEqY9Ysl4lYvy7Wah4nrVwghviU14vsVH3suWaCEVmj0i+/dQUxTySJDBWgdeCQxvQyU4VSwWaGbapYAncCIBZZGIJnuZYuTZ/jMKgM8jJWtyOCF+n0iA6n1VIa2U4IZ69/eXPzLC1Iz9HsZj5LUsIguFw1TgU2M5//jAVeMGjG1BKji9lZMx6CAGptSwYbw9Sn+n7TKrnfhlm8rpfrVKo48OkGn6Bx5qIrq6AY1UBNRFKMH9ISeHeM8Oi/O67I156xmjtEPOG+fDBeRxQ==</latexit><latexit sha1_base64="I0zVRlzAmaf+N8fGMnkfim9z4HY=">AAAB7XicdVDLSgMxFM34rPVVdekmWARXQ6YWO90V3bisYB/QDiWTpm1sHkOSEcrQf3DjQhG3/o87/8b0IajogQuHc+7l3nvihDNjEfrwVlbX1jc2c1v57Z3dvf3CwWHTqFQT2iCKK92OsaGcSdqwzHLaTjTFIua0FY+vZn7rnmrDlLy1k4RGAg8lGzCCrZOa3SEWAvcKReRXLkrVagCRH5YRQqEjVRSG5RAGPpqjCJao9wrv3b4iqaDSEo6N6QQosVGGtWWE02m+mxqaYDLGQ9pxVGJBTZTNr53CU6f04UBpV9LCufp9IsPCmImIXafAdmR+ezPxL6+T2kEYZUwmqaWSLBYNUg6tgrPXYZ9pSiyfOIKJZu5WSEZYY2JdQHkXwten8H/SLPnBuV+6KRdrl8s4cuAYnIAzEIAKqIFrUAcNQMAdeABP4NlT3qP34r0uWle85cwR+AHv7RML6o90</latexit>

axion-photon couplingaxions produced from photon conversion
induced by the electric field of ions andelectrons in the Sun.

Fe-57 nuclear transition:mono energetic 14.4 keV M1 transitioneﬀective axion-nucleon coupling

Emerge with keV-scale energies
In principle, axions from all 3 couplings canbe present at the same time.

XENON1T sensitive to all 3 channels via
coupling to electrons gae(electronic recoils via axio-electric eﬀect).

β (Ea): velocity (energy) of axion

Solar-Axion: Detection

19

Expected rate in xenon convolved with detector eﬀects (resolution, eﬃciency) and σpe
Atom. Data Nucl. Data
Tables, vol. 5, no. 1, pp.
51-111, 1973

σpe

5keV

Eﬀ.

>70%@2keV

Res.

~10%@low-E• For Primakoﬀ and 57Fe, can only deduce product of 2 couplings.
• All the three ﬂux components are considered completely independent of each other
̶> Model-independent search: parameters of interest =• XENON1T is more sensitive to DFSZ model, where axions couple to electrons at tree levelcompared to KSVZ model (couples to electrons at loop level)

Axion-like Particle / Dark Photon
Assuming ALPs/dark photons are non-relativistic and make up all of the local dark matter, theexpected signal is a mono-energetic peak at the rest mass of the particle

For ALPs

For dark photons

20Background Models

Background Model

22
214

Pb: main ER BG
検出器の表面に付着していて、絶えず湧き出してくる

Predicted energy spectra based on detailed modeling of each background component
Rates constrained by measurements and/or time dependenceBackground Model

Predicted energy spectra based on detailed modeling of each background component
Rates constrained by measurements and/or time dependence

23

Background Model

24

55.8 days

171.2 days

Time-evolution and model of 131mXe (generated by neutron activation)
Divided into two datasets, fit simultaneously.

SR1a

SR1b

•

SR1a: <50 days from neutron calibration,
includes more activated backgrounds•

SR1b: the rest, less activated backgrounds•

background model denoted B0

Unbinned Profile Likelihood Analysis

Profile over the nuisance parameters
Combining the likelihoods of the 2 partitions

Fit to Data

SR1a

SR1b

Fit

26

Decent matching across the whole energy range
in 1-210 keV(76 +/- 2) events/(t·y·keV) in [1, 30] keV
Lowest background rate ever achieved in thisenergy range!

Excess in 1-7 keV

27

Excess between 1-7 keV

285 events observed
vs.
232 events expected (from BG-only best-ﬁt)Would be a 3.3σ Poissonian ﬂuctuation

Are We Missing Something?

Event Location / Time-dependence

29

7% peak-to-peak rate modulation from L(sun, earth)• Uniform in 3D-space and cS1/cS2b plane• consistent with constant time (but with low statistics)

Efficiency / Reconstruction

30
220

Rn calibration reconstructs as

expected

220

212

Fit toRn ( Pb)
calibration data usingsame analysis framework

Validates eﬃciency andenergy reconstruction

β-decay of Pb212 is used
to calibrate detectorʼs
response to ER
backgroundg.o.f p=0.58
Again, unbinned ﬁt is performed here.

214Pb Spectrum Model
Calculated by X. Mougeot

31
Atomic screening and exchange eﬀects
can increase rate at low energies.
~6% uncertainty on the shape~50% needed to account for excess

241Pu

Good agreement between measurements
and calculation for 241Pu (Qβ=20.8 keV)and 63Ni (Qβ=67 keV)

241Pu (Qβ=20.8 keV)
• IAEA model: No screening/exchange eﬀects• GEANT4 model: only screening eﬀect• This work: both screening/exchange eﬀects
App. Radiat. Isot. 68, 1454 (2010)

Low-energy (Q value 18.6 keV)Long half life (12.3 years)

Tritium?
1. Cosmogenic production?
2. Atmospherically abundant?

Testing Tritium Hypothesis

33

Res.

Eﬀ.

Tritium favored overbackground-only at 3.2σ

Best-fit tritium rate:

159 ± 51 events/(t · y · keV)<latexit sha1_base64="lHUFcGQmaWarBmnvrJrLjDz+8rM=">AAACInicbVDLSgMxFM34rPVVdekmWIS6qTPVou6KblxWsK3QKSWT3mpoMjMkd4Qy1F9x46+4caGoK8GPMX0Iaj0QcnLuI/eeIJbCoOt+ODOzc/MLi5ml7PLK6tp6bmOzbqJEc6jxSEb6KmAGpAihhgIlXMUamAokNILe2TDeuAVtRBReYj+GlmLXoegKztBK7dyJVz6hfqxo2bvzFcMbrVK4hRDNYP/7XUCfdyKkfTq+e1DfG9B2Lu8W3RHoNPEmJE8mqLZzb34n4omyzblkxjQ9N8ZWyjQKLmGQ9RMDMeM9dg1NS0OmwLTS0YoDumuVDu1G2p4Q6Uj9WZEyZUxfBTZzOLX5GxuK/8WaCXaPW6kI4wQh5OOPuomkGNGhX7QjNHCUfUsY18LOSvkN04yjdTVrTfD+rjxN6qWid1AsXRzmK6cTOzJkm+yQAvHIEamQc1IlNcLJPXkkz+TFeXCenFfnfZw640xqtsgvOJ9f9PmjUw==</latexit>

3

H half-life 12.3 years (too long to observe in SR1)

3

H:Xe concentration:

6.2 ± 2.0 ⇥ 10<latexit sha1_base64="z/agMrUFvletRlZfEaWopBwFzAU=">AAACFXicbVDLSgMxFM3UV62vqks3wSK40HFmfC6LblxWsA/ojCWTZtrQZDIkGaEM9SPc+CtuXCjiVnDn35g+Ftp64MLhnHu5954wYVRpx/m2cnPzC4tL+eXCyura+kZxc6umRCoxqWLBhGyESBFGY1LVVDPSSCRBPGSkHvauhn79nkhFRXyr+wkJOOrENKIYaSO1igdntgf9hEPPdqCvKScKus5dduidDh58jnRX8owLdmRq0CqWHNsZAc4Sd0JKYIJKq/jltwVOOYk1ZkippuskOsiQ1BQzMij4qSIJwj3UIU1DY2TWB9noqwHcM0obRkKaijUcqb8nMsSV6vPQdA7vVNPeUPzPa6Y6uggyGiepJjEeL4pSBrWAw4hgm0qCNesbgrCk5laIu0girE2QBROCO/3yLKl5tntsezcnpfLlJI482AG7YB+44ByUwTWogCrA4BE8g1fwZj1ZL9a79TFuzVmTmW3wB9bnD18unSk=</latexit>

25

mol/mol

fewer than 3 tritium atoms
per kg of xenon!

1. Cosmic Activation of Xenon

34
Tritiated water (HTO)

Cosmogenic activationof xenon: ~32 tritium
atoms/kg/day (Zhang,
2016)
1 ppm water in bottles
implies tritium forms
predominately HTO.

HTO prediction
SR1 best-fit tritiumEﬃcient removal (99.99%)
in puriﬁcation system(SAES getter with hydrogen
removal unit)(note: tritium from activation
While underground is negligible.)

Expected concentration more than
100x smaller than measured

From puriﬁcation and handling, thiscomponent seems unlikely.

2. Atmospheric Abundance in Materials

35

What about T emanating from materials in equilibrium with removal?
*Hydrology measurements from IAEA nuclear database

HTO:H2O concentration*

5 10 ⇥ 10 18 mol/mol

HT:H2 concentration

Assuming same concentration as for H20<latexit sha1_base64="mG4x1FgX0WCdtIyyYrv8Fm9zEmk=">AAACF3icbVDLSsNAFJ34rPUVdelmsAhuGpOq2GXRjcsK9gFNLJPptB06k4SZiVBC/Ao3/oobF4q41Z1/46SNoK0HLhzOuZd77/EjRqWy7S9jYXFpeWW1sFZc39jc2jZ3dpsyjAUmDRyyULR9JAmjAWkoqhhpR4Ig7jPS8keXmd+6I0LSMLhR44h4HA0C2qcYKS11TevM5UgNBU/KqWNDV1FOJHTs26TsVNP7H5OH7FhX2jVLtmVPAOeJk5MSyFHvmp9uL8QxJ4HCDEnZcexIeQkSimJG0qIbSxIhPEID0tE0QHq9l0z+SuGhVnqwHwpdgYIT9fdEgriUY+7rzuxOOetl4n9eJ1b9qpfQIIoVCfB0UT9mUIUwCwn2qCBYsbEmCAuqb4V4iATCSkdZ1CE4sy/Pk2bFck6syvVpqXaRx1EA++AAHAEHnIMauAJ10AAYPIAn8AJejUfj2Xgz3qetC0Y+swf+wPj4BgjEn0A=</latexit>

Required (H2O + H2):Xe
concentration to explain

60—120 ppb

Tritiated molecules can emanate into LXe target from water and hydrogen in
detector materials in the form of HTO and tritiated hydrogen (HT).
emanation in equilibrium with removal.

But…
H2O in XENON1T: O(1) ppb,
otherwise can not detect light

H2O

H2
O2 in XENON1T: <1ppb, otherwise
can not drift electrons
H2 ~100 ppb? -> ~100x higher thanO2 possible?

Summary of Tritium Hypothesis

36

Many unknowns about tritium in a cryogenic LXe environment• Radiochemistry, particularly isotopic exchange (formation of other molecules?)• Diﬀusion properties of tritiated molecules• Desorption and emanation• For HT, no direct measure of either abundance or H2 concentration.

柿内さんのトーク！
We can neither conﬁrm nor exclude the presence of tritium.

Ar37? (時間があれば)
1. In-situ production?
2. Atmospherically abundant?
3. Air leak?

Ar37

38

37Ar K-electron capture to the ground state of 37Cl (37Ar -> 37Cl + νe)• Half-lifetime of 35 days & 2.8 keV energy in X-rays & Auger e- s
• Calibration with 37Ar performed in XENON1T at the end of SR2
̶> good understanding of the detector at those energies

Physics of Atomic Nuclei volume 70, pages 300–310(2007)

Possible 37Ar contributions:
1. Its presence in the xenon gas before ﬁlling,
2. A possible air leak that could provide a constant source of argon.
3. In-situ production: neutron reactions with 36Ar or 40Ca

Ar37 Distillation

Possible 37Ar contributions:
1. Its presence in the xenon gas before ﬁlling
̶> Argon is strongly reduced by 90 days of distillation & decay:
combined time constant ~ 1.8 days, >10 times faster than decay
2. A possible air leak that could provide a constant source of argon. ̶> ~ 3 L/day air leak
̶> ruled out by natKr measurement (RGMS, < 1ppt increase/yr = ~1L/year air leak)
3. In-situ production: neutron reactions with 36Ar or 40Ca
̶> Negligible

39Signal Interpretation?

Solar-Axion Results• All the three ﬂux components are considered completely independent of each other• Parameters of interest in the Proﬁle Likelihood =• Signiﬁcance determined using toy-MC methods

Axion favored over background-only at 3.5σ41

Solar-Axion + Tritium

Axion + 3H favored over 3H hypothesis at 2.1σ

When both axion and tritium are included in the fit, thebest-fit of tritium is zero — in favor of axions.

42

Solar-Axion Results

43

Parameters of interest in the proﬁle likelihood

Best-fitg̲ae: 3.1e-12g̲ag: 8.1e-11g̲an: 7.6e-7

ABC and Primakoﬀ components are both low-energy signals, the favored region is anti-correlated
in this space
̶> suggests either a non-zero ABC component or non-zero Primakoﬀ component.
In tension with astrophysical constraints from stellar cooling bounds from the horizontal
branch stars and red giants

Inverse Primakoff Process?

44

2006.14598

Events / (t·y·keV)

eff
ga = 2.7 · 10 10 GeV 1 , gae = 4.5 · 10 12 , gan= 10 6140

XENON1T B0 model120

ABC Flux + Inverse Primakoff
Primakoff Flux + Inverse Primakoff
57
Fe Flux + Inverse Primakoff
XENON1T SR1 Data

100
80
60
40
20
0

2006.15118
0

5

10

15

20

25

4
30

E [keV]

10 8
Primakoff (2 B0 exclusion)Primakoff + 3 H (2 SR1 fit)

FIG. 2. The event rate distributions for inverse Primako↵
scattering in inverse
LXe forPrimakoﬀ
a ton-yearprocess
exposurecan
from Primako↵Considering
57
produced,and coolingFe-produced
axions are
weakentheABC-produced,
tension with stellar
constraint
shown for select choices of axion couplings, and added to the“B0 ” background model.

Primakoff (2 SR1 fit)

10 10
HB Stars

10 12
10 4

XENON1T has a good sensitivity also for g̲aγ!

2

I

=
/N
E
VZ
KS

VZ

E

/N

10 11

DF
SZ

=

44

/3

CAST

KS

ga (GeV 1 )10 9

2006.15118
10 3

10 2

10 1

ma (eV)

100

101

102

sis performed by XENON1T (see also [34, 48–50]). Also,
it is possible that axions undergo inverse Compton scattering o↵ electrons at rest in LXe, ae ! e [13], but
this is a subdominant process (/ Z) in comparison toAxion-like Particle / Dark Photon
Fitting a mono-energetic peak to theexcess: 2.3 +/- 0.2 keV

4.0 σ local
3.0 σglobal

Best ﬁt: ~60 events/tonne/year
4.0 σ local signiﬁcance
3.0 σ (global, consideringlook-elsewhere eﬀect).

45

Summary

46

Solar axion
favored overbackground-only at
3.5σ

Tritiumfavored overbackground-only at
3.2σg̲ae: 3.1e-12g̲ag: 8.1e-11g̲an: 7.6e-7

Neutrino magnetic
moment (see backup
slides) favored overbackground-only at
3.2σ

Axion + 3H favored
over 3H hypothesis at
2.1σ

μ_ν: 2.3e-11

Monoenergetic peak at 2.3 +/- 0.2 keVfavored over background-only at 3.0σ
(global)

47

Back UpStatistical Fluctuation?

statistical ﬂuctuation? (see 17 keV dip)

Note: we use an unbinned proﬁle likelihood analysis

48

XENONnT

7

Fig. 7 The cryogenic system of XENON1T: cooling is provided by means of three redundant cold heads (two pulse-tube refrigerators (PTR),
1 LN2 ), installed on individual cooling towers located outside of the water shield. The liquefied xenon runs back to the main cryostat in a 6 m longvacuum-insulated cryogenic pipe, through which all connections to the TPC are made with the exception of the cathode bias voltage which is notshown in the figure. The connections to the systems for xenon purification and storage (ReStoX) are also shown. Figure not to scale.

49

XENONnT

50

8Fig. 8 Piping and instrumentation diagram (P&ID) of the XENON1T purification system. The system also serves as the main interface to the othercomponents of the gas-handling system (see figure 9) and allows the insertion of short-lived isotopes for calibration. Some instrumentation suchas temperature and pressure sensors, as well as several access ports are omitted for clarity. The path of the xenon gas during standard purification
is indicated in blue.

Ar37

51

Two possible 37Ar contributions:
1. Its presence in the xenon gas before ﬁlling,
2. A possible air leak that could provide a constant source of argon.
1. Its presence in the xenon gas before ﬁlling,• Removal time in distillation is ~1.8 day, directly demonstrated at 1T using a dedicated 37Ar source• We had ~90 days of the online 85Kr distillation before SR1 (22 orders of magnitude reduction)• The isotopic abundance of 37Ar is ~ 10­20

Even if there were 1 ppm of nat Ar in the xenon originally, the 37Ar concentration
would have been reduced to a negligible level (~10-48 mol/mol)Ar37(sea-level) Ar37 activation rate of 51 atoms/(kgAr · day)52

2. A possible air leak that could provide a constant source of argon.
Require: ~ 10­4 kg of argon per day, corresponding to a total air leak of ~ 3 L/day.
̶> Ruled about by the nat Kr concentration, which increased by < 1 ppt/year during SR1 as
informed by RGMS measurements

1-ppt/year increase in natKr would correspond to an air leak of ~ 1L/year in XENON1T.
Also TPC would not work in such a leaky condition because of O2...

2.3 +/- 0.2 keVBest-ﬁt mass is 2.3 +/- 0.2 keV, so far
from 2.8 keV

target due to cosmogenic activation of the Xe during itsergy ER calibration.
127
Ouranalysis
focusesonthe
Xe decay events that intime on the surface before being brought one mile un53
derground. The surface production rate is modeled andvolve a single gamma-ray emission followed by an atomic
estimated using ACTIVIA and described in [24]. The de-cascade. The two energy depositions are sufficiently spaseparated
to beindividually identified in the LUX
Xe can be produced
fromit cosmogenic
Xe at sealevel;
cay127characteristicsof 127 Xe makean appealing activation
mono-tially ofenergetic source for LUX ER energy calibration. Thisdetector. The IC electrons are not considered in thisGiven theshortof 36.4days
and thefact
thatthetoxenon
gas wasfor thework
due
their shortrangeundergroundin Xe, which causes
calibration
coversthehalf-life
entire signal
regionrelevant
to theO(1)search,yearsreaching
before allthetheoperation
WIMP
way downof
to XENON1T
the obser-nuclear and subsequent atomic de-excitation signals tovation of 186 eV energy deposition. This represents thealways spatially overlap [7]. The sub-dominant compo̶> alreadyER
decayedaway
lowest-energy
in situ measurementsthat have beennent of decays with multiple gamma-ray emission are notconsidered, as the complexity of their event energy reconexplored in LXe to date.
Rev. D 96,uncertainties
112011 (2017) instruction leads to unnecessaryPhys.
systematic
127Xe 1/2+ the analysis.

375.0

47.6%

202.9

53.0%

≈

36.4 d

127

127

Xe

I

%

14

5.
3

2.
9
20
31

1.

24
%

57

.6

4.

%

7/2+
1.86 ns

cascade X-ray/ Auger electron

2.
10.0143%

17
.7
68

3/2+
0.39 ns

618.4

%
.7
25

17

1/2+
≤135 ps

.3

%

37

5.
0

0.

3/2+

01
4
61 3%
8.
4

Xe127

57.6
0.0

QEC = 662.3

νe

γ-ray

FIG. 2.
A schematic illustrating atomic electron capture(a K-shell electron in this case), for a 127 Xe nucleus, which
127I
is converted into 127 I in an excited state. The excited 127 I
FIG. 1. Decay scheme of 127 Xe [25] with units of keV. Thenucleus can subsequently de-excite via emission of one or
127 Also we did not see high-energy
more gamma
γsthat
accompany
X-raysrays (or IC electrons). The atomic structure
Xe decays via electron capture to 127 I.
The
percentage
de-excites through X-ray (or Auger electron) cascade emisabove
thearetransition
the gamma-ray
as sofrac(We
using arrow
innerisvolume
for thisintensity
search,there is a O(1)cm between FV and the detector
sions.
tion of parent (127 Xe) decay.
5/2+
stablewall)

The nuclear and atomic de-excitations of 127 I can betreated as prompt (ns timescale [25]) and simultaneousβ/γ discrimination? NEST?

54

214Pb Spectrum Model

Calculated spectra by X. Mougeot 56

Exchange eﬀect
β electron is created in an atomic orbital of the daughter atom and the atomic electron which
was present in the same orbital in the parent atom is ejected to the continuum.
This process leads to the same ﬁnal state as the direct decay, i.e. one electron in thecontinuum, and is possible because the nuclear charge changes in the decay.

Screening eﬀect
The electrons in bound states in the atom produce screening of the nuclear charge for theemitted beta particle. This change in electromagnetic ﬁeld modiﬁes the beta spectrum.
(The atomic screening eﬀect corresponds to the inﬂuence of the electron cloud surrounding thedaughter nucleus on the β particle wave function)

241Pu / 63 Ni
beta-spectrum
Ni

From X. Mougeot 57

63

M. Loidl et al., App. Radiat. Isot. 68, 1454 (2010)

Analytic: 𝐸 = 17.45 keV
Calculated as allowed
Mean energy
theWithofscreening:
𝐸 = 17.40 keV
spectrum decreased
Experimental spectrum
Withscreeningandexchange:
𝐸 = 17.14 keV
by 4 %
M. Loidl et al., App. Radiat.
Isot. 68, 1454 (2010)en 2017 | X. Mougeot – Beta spectrometry | 31

C. Le-Bret, PhD thesis, Université Paris 11 (2012)

Mean energy of thespectrum decreasedby 1.8 %Allowed transition
Experimental spectrum
C. Le-Bret, PhD thesis,
Université Paris 11 (2012)

TU Dresden 2017 | X. Mougeot – Beta spectrometry | 30

S2-ONLY ANALYSIS
S2-only = No requirement on S1s, allowing for a ~200 eV threshold50
3H

Events / bin

20

Solar axion (ABC)⌫ magnetic moment
Background

10
5
2
1
0.5
0.2

200

500

PRL 123, 251801

S2-only analysis
allows for a lower
energy threshold of
200eV

2000

S2 [PE]µ⌫ < 3.1 ⇥ 10 11 µB<latexit sha1_base64="LSUULtWfe0NV92tuaVK062Ayp14=">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</latexit>

gae < 4.8 ⇥ 10

1000

12

<latexit sha1_base64="lME4KwDSBlr7mwB8oGTOt8EfB6c=">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</latexit>

RH3 < 2256 events/t/y

consistent with this work
for all 3 hypotheses<latexit sha1_base64="f+GwG/6cXr9cm3vTl/XzGD6WAV4=">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</latexit>

larger upper limits, S2-only analysis is notsensitive to the excesss we foundOther Experiments: PandaX?

59

Exposure: 101 ton-days (XENON1T: 236 ton-days)

1.4
1.2
1
0.8
0.6
0.4
0.2
0

1.4

XENON1T

Run11-1 (24.2 ton ⋅ day)

1.2
1
0.8
0.6
0.4

5

10

15

20

0.2
0

25
0

Energy[keV]Run11-2(37.1 ton ⋅ day)
1.4

Events/ton/day/keV

Events/ton/day/keV

1.4
1.2
1
0.8
0.6
0.4
0.2

Run10 (19.4 ton ⋅ day)

PandaX

Events/ton/day/keV

Events/ton/day/keV

3
BG level: ~5 times higher BG than in XENON1T

5

10 15 20
Energy [keV]

1.2
1
0.8
0.6
0.4
0.2
0

5

10 Energy[keV] 15

20

Data

Total Fitted

Flat ER

85

Tritium

127

25

Kr
Xe

arxiv: 2008.06485

5

10 15 20
Energy [keV]

Note2:that
PandaX
injectedfor
Tritiated
FIG.
Electronrecoilexperimentenergy distributions
Runs Methane (CH3T) directly into the detector for
10, 11-1,
and 11-2 withbackground-only
pre-fits.
low-E
calibration,
but they
could not completely
remove it with distillation.
Likelihood fits are performed in two-dimensional space.
136
The
backgrounddue toXe, neutron,
accidentals
Resultingtritium
concentration
is and~0.04
uBg/kg (~5 10-24 mol/mol in xenon)
is negligible, thus omitted in the figure.
Best-ﬁt for tritium hypothesis in XENON1T: ~6 10-25 mol/mol (we did not inject CH3T!)

Other Experiments: PandaX?

arxiv: 2008.06485

Exposure: 101 ton-days (XENON1T: 236 ton-days)

60
4

BG level: ~5 times higher BG than in XENON1T
−11

−11

0

160

0

0

140

85

Kr
Tritium

120

136

100

XENON1T

0

20
0
5

σ

Xe

This Work
This WorkLUX
LUX
XENON1T
XENON1T

136

Xe++Neutron
Accidental + Neutron
Xe + Accidental

XENON1T

60
40

2
0
2
0

127

127
Tritium
Xe

80

0

0

85

Kr

Flat ER

2
0
−2
0
5

−12

10

gAe

0

Data
Total
Fitted Total
FlatFitted
ER

gAe

0

Data

Events/keV

0

10

10

−12

10

Red Giant
Red Giant2χ 2 = 22.7
5
10

10
15

15
20

χ = 22.720
25

25

Energy [keV]
Energy [keV]

−13

10

−13

5
10
15
10
15
20
Energy [keV]
Energy [keV]

20
25

25

10

10

5

10 4− 310− 3 210 2 1
10Axion Mass
10 [keV/c
10 2]
Axion Mass [keV/c2]

10 5 4
10

10 1
1

1

FIG. 4: The 90% C.L. upper limits on the solar axio
FIG. 4: The
90%
C.L. upper
on withthe with
solar
axion
FIG. 3: Electronenergy the
distribution
totalstrength
Expected
excessrecoil
assuming
best ﬁt for
signalfrom
XENON1T
is ,limits
compatible
coupling
constantgoverlaid
thatfrom LUX
AeG. 3: 100.7
Electronrecoilenergydistribution
for
total
ton-day
data. uncertainties,
Simultaneous bestfit
backgroundcoupling
constantgAe, overlaid
with(90%)
that
from
LUX
their
data
within
but
their
data
are
also
consistent
withbackgroundonly
2017
[32].
The
best
fit
regionfrom
XENON1
7 ton-daydata.
Simultaneous
best
fit
backgroundcontributions are overlaid, where tritium background 2017
is[32].
The[18]best
fit
region
(90%)
from
10
1 XENON1T
excess
for
g
<
10
GeV
is shown as shadA
hypothesis
ibutionstreatedare overlaid,
wheretritiumbackgroundis10
1
as common in Run 10 and Run 11. The excess [18]forgA <The10 green
GeV
is shown
as shadedgrey
region.
andyellow
bands
represent t
eatedexpected
as common
in
Run
10
and
Run
11.
The
axion signal with XENON1T best fit signal
grey region.
and yellow
bands
represent
theline±1 Theandgreen
2 sensitivity
bands
and
the dashedected axion
signalwith XENON1T
fit line.
signalstrength
is because
shown as best
dashed̶> Noconclusionof lower
statistics & ±1
higher
andBG
2 sensitivity
bands
and theDerived
dashedupper
line bourepresents
the mediansensitivity.

PandaX / LUX?

#!/Xe is produced from cosmogenic

61

)!(

Xe

activation and has a short half-life of
36.4 days
Xenon gas used in XENON1T wasunderground for O(years)

L-shellM-shell

LUX Collaboration, PRL 118, 261301

low-z-origin γ rays (dark green),other γ rays (light green),
85Kr or Rn-daughter contaminants in the liquid
xenon undergoing β decay (orange)
x rays due to 127Xe (purple).

53

62

PHOTON/CHARGE YIELD FOR ER / NR
NR Photon yield[ph keV 1]

XENON100 (530 V cm

20

1)

Aprile 2005 (0 V cm 1)
Aprile 2006 (2 kV cm 1)
Aprile 2009 (0 V cm 1)
Plante 2011 (0 V cm 1)

15

Sorenson 2009 (730 V cm 1)
Manzur 2010 (0 V cm 1)
Manzur 2010 (1 kV cm 1)
LUX 2017 (180 V cm 1)

10

New results!

15

XENON1T this result (82 V cm 1)

NR charge yield[e keV 1]

NR

25

NEST v2.0 (82 V cm 1)

5

arXiv: 1902.11297

12

9

Estimated using 220Rn (ER)3
> 10% efficiency

36
10Energy [keVnr]

3050

LUX (CH3T, 105 V cm

1

3
6
10
Energy [keVnr]

30

50

80

XENON1T this result (82 V cm 1)
XENON100 (CH3T, 92 V cm 1, cred. region)

For charge yield, there is a

70

1)

LUX (127Xe, 180V cm 1)
PIXeY (37Ar, 200 V cm 1)

40

0.5

ER charge yield[e keV 1]

50
ER photon yield[ph keV 1]

ER

60

1

and 241Ambe / Neutron
Generator (NR) calibration
data.

6

> 10% efficiency

0.5

4NEST v2.0 (82 V cm 1)
Error bars are stat. + sys.

30
20

127

0.186 keVee ( Xe)measurement from LUX

60

Phys. Rev. D 96, 112011

50
40

1e- produces ~30 PEs.
Photo-detection eﬀ ~ 10%30

10> 10% efficiency

0.1

‣
‣

0.3

0.6

1
3
Energy [keVee]> 10% efficiency

20
6

10

20

0.1

0.3

0.6

1
3
Energy [keVee]

6

10

20

FIG. 1: Mean photon and charge yields of NR (upper panels) and ER (lower panels) in the XENON1T calibration data fit.
The bluesolid line andfor
shadedregion represent
the pointcorresponds
estimation and 15%-85%
region,deposit
respectively, ofof the~1keV
posterior. for ER and ~4 keV for NR
10%
eﬃciency
S1&S2
analysistocredible
energyData points for upper panels are from fixed-angle neutron scattering measurements [22–28]. Results of XENON100 [17] using
data-Monte Carlo (MC) matching on the 241 AmBe calibration method are shown with the red solid line and shaded region.
ERThesignalscansigniﬁcantly
detectioneﬃciency̶>highersensitivity
for low-mass WIMPs.
best fit fromNEST
v2.0 [21] is shown enhancewith the black thesolid line.
The measurementsfrom [19, 20,
29, 30]are shownalongwith the best fit of NEST v2.0 [21] in lower panels. The vertical dashed blue lines indicates the energy threshold for XENON1T
NR and ER calibrations, below which the detection efficiency drops to less than 10%.

‣ Moreover, S2-only analysis can also decrease the threshold from 1 keVee to 0.186 keVee

Xe

QCD axion models

X E N O N
Dark Matter Project

DFSZ: two Higgs doublets model
couplings to leptons at tree level

KSVZ: heavy quark model
couplings to leptons only at loop level

quarks/electrons related by Beta

photons/electrons related by E/N

Dine-Fischler-Srednicki-Zhitnitsky (DFSZ)

Kim-Shifman-Vainshtein- Zhakharov (KSVZ)

axion-photon couplingsame for both models• relative contributions from each component can allow to distinguish between models(Primakoﬀ dominates in KSVZ models); can also constrain βDFSZ• nuclear transition contribution always relatively small

the ABC flux is dominant in DFSZ models, while the Primakoff flux is dominant in KSVZ models.
63

Xe

QCD axion models
DFSZ: two Higgs doublets model
couplings to leptons at tree level
quarks/electrons related by Beta

Dine-Fischler-Srednicki-Zhitnitsky (DFSZ)X E N O N
Dark Matter Project

KSVZ: heavy quark model
couplings to leptons only at loop level
photons/electrons related by E/N

Kim-Shifman-Vainshtein- Zhakharov (KSVZ)

axion-photon couplingsame for both models• relative contributions from each component can allow to distinguish between models(Primakoﬀ dominates in KSVZ models); can also constrain βDFSZ• nuclear transition contribution always relatively smallMichelle Galloway for XENON | Zooming in on Axions in the Early Universe

64

Solar axion/ALP fluxABCXe

X E N O N
Dark Matter Project(Atomic recombination and deexcitation,
Bremsstrahlung and Compton)

Primako!:Fe-57 nuclear transition:

k: momenta of axion, photon
Michelle Galloway for XENON | Zooming in on Axions in the Early Universe

65

Xe

Statistical inference

X E N O N
Dark Matter Project

3D confidence volume (90% C.L.)

Primako!

Projected onto 2D regions

gae < 3.7 ⇥ 10 12

ef f
gae gan< 4.6 ⇥ 10 18<latexit sha1_base64="axhHK6wo1sJwVJ1gGAsvLW4rOrc=">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</latexit>

gae ga < 7.6 ⇥ 10 22 GeV 1

ABC

Discrepancy with astrophysical constraints fromstellar cooling(arXiv:2003.01100)
Michelle Galloway for XENON | Zooming in on Axions in the Early Universe

66

Xe

Statistical inference

X E N O N
Dark Matter Project

57Fe

3D confidence volume (90% C.L.)

gae < 3.7 ⇥ 10 12

ef f
gae gan< 4.6 ⇥ 10 18<latexit sha1_base64="axhHK6wo1sJwVJ1gGAsvLW4rOrc=">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</latexit>

gae ga < 7.6 ⇥ 10 22 GeV 1

Poor fit for small ABC rate

ABC

Discrepancy with astrophysical constraints fromstellar cooling(arXiv:2003.01100)
Michelle Galloway for XENON | Zooming in on Axions in the Early Universe

67

Xe

Solar axion/ALPX E N O N
Dark Matter Project

3D confidence
volume (90%
C.L.)
Projected onto
2D regions

Primakoff and 57Fe components can be absent if
the ABC component is present

No statistical significance forPrimakoff or 57Fe on their own

Michelle Galloway for XENON | Zooming in on Axions in the Early Universe

68

Xe

Neutrino magnetic moment<latexit sha1_base64="H5Qs1wQ5K/8loynvCHbwllGQyI4=">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</latexit><latexit sha1_base64="MYza2qo5NbFCH7bcvfCY768tof0=">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</latexit>

✓

1
Er

1
E⌫

◆

A larger value would imply new physics, andpossibly solve Dirac vs Majorana.

In the (extended) SM:µ⌫ ⇡ 3 ⇥ 10 19

d µ= µ2⌫ ↵dEr

X E N O N
Dark Matter Project

⇣m ⌘
⌫

eV

µB

µ⌫ & 10 15 µB<latexit sha1_base64="tFybRTB8kSOZb8XcxcUTDHWTTtE=">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</latexit>

Michelle Galloway for XENON | Zooming in on Axions in the Early Universe

Majorana
fermion69

Neutrino magnetic moment

Michelle Galloway for XENON | Zooming in on Axions in the Early UniverseXe

X E N O N
Dark Matter Project

70

Xe

Background Fit

X E N O N
Dark Matter Project

Component

Expected
EventsFittedEventsConstant in time?
(shared across partitions)214Pb(3450, 8530)

7480 +/- 160

YES

85Kr

890 +/- 50

773 +/- 80

NO

136Xe

2120 +/- 210

2150 +/- 120

YES

133Xe

3900 +/- 410

4009 +/- 85

NO

131Xe

23760 +/- 640

24270 +/- 150

NO

83mKr

2500 +/- 250

2671 +/- 53

NOMaterials

323 (fixed)

323 (fixed)

YES

Solar neutrino

220.7 +/- 6.6

220.8 +/- 4.7

YES

KK

125 +/- 50

113 +/- 24

YES

KL

38 +/- 15

34.0 +/- 7.3

YES

LL

2.8 +/- 1.1

2.56 +/- 0.55

YESK

79 +/- 33

67 +/- 12NOL

15.3 +/- 6.5

13.1 +/- 2.3NOM

3.4 +/- 1.5

2.94 +/- 0.50

NO

124Xe

125I

unconstrained in the fit
Michelle Galloway for XENON | Zooming in on Axions in the Early Universe

71

Xe

Probabilities

X E N O N
Dark Matter Projectslide credit: Jelle Aalbers
Michelle Galloway for XENON | Zooming in on Axions in the Early Universe72