the xenon dark matter project

The XENON Dark Matter ProjectLatest Results and Future Prospects

Constanze HasterokFor the XENON Collaboration

DPG Frühjahrstagung, Aachen 28.03.2019

28.03.2019 Constanze Hasterok (MPIK) 2

Indications for Dark Matter● Galactic Rotation Curves● Gravitational Lensing● Bullet Cluster● Cosmic Microwave

Background (CMB)● Structure Formation● Etc.

Bullet Cluster, Gravitational LensingNASA, Chandra x-ray observatory

CMB, arXiv: 1303.5062

arXiv: 0812.4005 [astro-ph]

Weakly Interacting MassiveParticles (WIMPs) are a favoured

model for dark matter!

Weakly Interacting MassiveParticles (WIMPs) are a favoured

model for dark matter!


WIMP Detection Strategies

Direct Detection Ind

ir ect D

ete

ctio

nP

rod

ucti

on

at

Collid

ers

XENON, LUX, DEAP, CRESST, PICO, DAMA ...

Fermi, Ice Cube, AMS,...

ATLAS, CMS, ...


The dual-phase TPC Technology● Light from prompt scintillation

(S1) and ionization (S2)● 3D position reconstruction● Background discrimination


The XENON CollaborationLaborati Nazonali del

Gran Sasso (LNGS), Italy

~170 scientists from 27 institutions


The XENON StoryXENON10 XENON100 XENON1T XENONnT

2005-2007Total: 25 kgTarget: 14 kgLimit: 8.8 x 10-44 cm-2


From 2019Total: ~8000 kgTarget: ~6000 kgSensitivity: 10-48 cm-2



The XENON1T Infrastructure

Water Tank with Cherenkov Muon Veto

Cryostat with TPC

Cryogenic Systems + Purification System

Data Acquisition Systems

Distillation Column

&Gas Analytics

Xenon Recovery and Storage

Eur. P

hys

. J. C

77,

881 (

20

17)

Cryo-Pipe with cables


XENON1T Science DataMore than one calendar year of stable data taking

SR0 – 34 live days SR1 – 247 live days

Eart

hq

uake + ~3 months

more data,→ being analyzed


Background Composition Electronic Recoils Nuclear Recoils

Surface EventsAccidental Coincidences

Reference region:

(NR median, -2σ)

Major Backgrounds:● ER: 69% (in reference region)● NR: 26% (in reference region)

Detector-Artefacts: 5%(in reference region)


Electronic Recoil BackgroundControlled by:● Screening of materials during detector

construction● 222Rn emanation measurements of materials● Cryogenic distillation of krypton● Fiducial volume selection

SourceFraction of ER

tot [%]

In 1.3T volume, (1-11)keV

222Rn 7585Kr 10

Solar Neutrinos 3

Materials 11136Xe 1

~80 evts/(t·y·keV)

Lowest ER background rate

ever achieved in a DM detector

XENON Preliminary


Nuclear Recoil Background Controlled by:

● 3600 m.w.e rock overburden

● Water Cherenkov Muon Veto

● Screening of materials during detector construction

● Fiducial volume selection

● Single scatter requirement

● Total rate (NRtot): ~ 0.8 evts/(t·y)

SourceFraction of NR

tot [%]

In 1.3T volume, (5-41)keV

Radiogenic neutrons 96

CEνNSNS 4

Muon-induced neutrons < 1


Event Distribution/Interpretation

● SR0 data re-analysis (32.13 d) + SR1 data (246.74 d): 279 live days● Results interpreted with unbinned profile likelihood analysis in (S1,S2,R)

space + segmentation of Z space into two bins arXiv:1902.11297

● Piecharts indicate the relative PDF from the best-fit of SI nucleon scattering of a 200 GeV/c2 WIMP with cross-section 4.4x10-47cm2

PR

L 12

1, 1

11

30

2 (2

01

8)


● Most stringent limit for WIMPs > 6 GeV/c2

● Minimum: 4.1x10-47

cm² for a WIMP of 30 GeV/c2

● Factor 7 better sensitivity compared to other LXe TPCs

● Editor‘s Suggestion PRL 121, 111302 (2018)

Spin-Independent WIMP-nucleon scattering

XENON1T DM Search Results



● 129Xe (spin-1/2): abundance of 26.4%● 131Xe (spin-3/2): abundance of 21.2%● Most stringent constraint on neutron-only interactions for WIMPs > 6 GeV/c2

● Minimum: 6.3 · 10-42 cm² @ 30 GeV/c2

Spin-Dependent WIMP-nucleon scattering

arX

iv: 19

02.0

3234



● Model assumptions:– WIMP is Dirac fermion– Spin-1 mediator with axial-vector couplings– Isoscalar WIMP-nucleon interactions

Spin-Dependent WIMP-nucleon scattering:Comparison to Colliders in Simplified Model

arX

iv: 1902.0

32

34



● XENON1T produced first experimental results!● Minimum of upper limit: 6.4 · 10-46cm2 @ 30 GeV/c2

Scalar WIMP-Pion coupling

PR

L 12

2, 0

71

30

1 (2

01

9)


Upcoming XENON1T Results:Dark Matter Searches

Search for electron-DM interactions:● ALPs● Dark Photons● SuperWIMPs

Low mass WIMP searches(S2 only analysis)

Monoenergetic lines in the ER background


Upcoming XENON1T Results:Nuclear Physics

Double Electron Capture of 124Xe

Neutrinoless double beta decay of 136Xe

XENON Preliminary

● QEC = 64.3 keV

● T1/2 > 2.1 · 1022 y (XMASS)

● Qββ = 2458 keV

● T1/2 > 1.07 · 1026 y

(KamLAND-Zen)

KamLAND-Zen

XENON Preliminary

XENON Preliminary


Goodbye XENON1T!Detector turned off on December 10th 2018


Time to Relax?


No! → Detector Disassembly


Upgrade XENONnT


XENONnT Strategy

Minimal Upgrade● Re-use XENON1T

infrastructure● Only exchange

TPC

Fiducial LXe Target● Total LXe: 8 tons● Fiducial mass: ~4

tons

Background● Reduce 222Rn

induced backgrounds by a factor of ~10

Fast Turnaround● XENONnT

commissioning in 2019


New Features of XENONnTNew TPC

● PMT number increased by factor of 2

● Length: ~1.5 m Diameter: ~1.3 m

LXe-Purification● To achieve fast

cleaning of larger LXe volume (2500 SLPM)

● GXe purification (120 SLPM)

Neutron Veto● Gd in the Water

tank: 0.5% of Gd2(SO4)3

● 120 PMTs 8-inch PMTs (same as for Muon-Veto)

Radon-Distillation Column

● High throughput of 200 SLPM to extract Rn from TPC and remove from LXe


Summary/OutlookXENONnT is on its way! Commissioning in 2019

Ongoing XENON1T Analyses:● Low mass WIMP searches with S2-only● DM-electron interactions: ALPs,

DarkPhotons, etc.● Double electron capture of 124Xe →

currently most sensitive experiment for this process

● Neutrinoless double beta decay of 136Xe

● Etc.

→ Stay Tuned!→ Stay Tuned!

the xenon dark matter project

Documents