Highlights on Dark Matter Experiments Overview & Basics

On the News: DAMA/LIBRA, CDMS, XENON, CRESST, Others Selected Projects

Low-Mass WIMPs: CoGeNT, CDEX-TEXONO

China Jin-Ping Underground Laboratory

(Personal) Perspectives & Prospects Henry T. Wong / 王子敬

Academia Sinica / 中央研究院

November 2011 @

我們「已瞭解」的宇宙之組成

基本粒子

原子核 原分子 「已瞭解」的萬物

載力者

+反物質

Higgs (未被發現)

粒子物理的世界

最大跟最小的物理是一致的!

宇宙演化

的標準模型

時間能量溫度

？？

Compositions of the Universe : We only Understand ~4% !!!????

Standard Model Matter：Understood

Dark Matter：”We know Nothing !” (but perhaps have reasonable guesses)

Dark Energy：”We know less than Nothing !”

Or …. The Ultimate Copernicus Principle !!

Dark Matter: Obey Known Laws of Gravitation.

Dark Energy: Does NOT.

Evidence for Dark Matter

Spiral galaxies Rotation Curve

⇒ Missing Ω (Galactic) Clusters & Superclusters Gravitational Lensing

⇒ Missing Ω (Cluster) Large Scale Structures

⇒ Cold Dark Matter CMB Anisotropy

⇒ Ωtotal ; Ωbaryon (cosmological) Big Bang Nucleosynthesis

⇒ Constrain Baryon density

Large-Scale Structures & Cosmic Microwave Background sensitive to initial fluctuations & their evolution - which depends on nature of DM @ cosmological scale.

Density perturbations (inflation?)

Nucleosynthesis

t = 10-35 s

t ~ 1 mn

t ~ 300000 yrs

Photons: Free propagation

Galaxies, clusters

Recombination: p+e- → H+γ

CMB : “background” @ T0 = 2.7 K NOW

Matter: Gravitational collapse

CMB LSS

BBN

The Nobel Prize in Physics 2011 was divided, one half awarded to Saul Perlmutter, the other half jointly to Brian P. Schmidt and Adam G. Riess "for the discovery of the accelerating expansion of the Universe through observations of distant supernovae".

The Nobel Prize in Physics 2011 Saul Perlmutter, Brian P. Schmidt, Adam G. Riess

BBN/CMB : ΩB (~ 4%) < LSS: Ωm (~ 28%) [Non baryonic dark matter]

LSS: dark matter is “cold” [non-relativistic]

Ωm (~ 28%) < Ωtot (~ 1) [CMB] : ΩΛ

Crisis/Opportunities of Basic Science

Ωtotal ≅ 1 > Ωmass > Ωbaryon > Ωluminous

Dark Energy

Dark Matter

stable (protected by a conserved quantum number) no charge, no colour (weakly interacting) cold, non-relativistic (mass >> kinetic energy) relic abundance compatible to observation motivated by theory (vs. “ad hoc”)

halobulge

disksun

Properties of a Good Cold Dark Matter Candidates:

Dark Matter Current Wisdom: Gravitationally bounded in

galactic halo Velocity distribution being

Maxwellian

(Incomplete) List of CDM candidates RH neutrinos Axions Lightest Supersymmetric

particle (LSP) – neutralino, sneutrino, axino

Lighest Kaluza-Klein Particle (LKP)

Heavy photon in Little Higgs Models

Solitons (Q-balls, B-balls) Black Hole remnants …

Current Wisdom (?): Most Experimental Programs focus on the Search of WIMPs Key Variables: mass & cross-sections

Dark Matter is DARK (not interacting electromagnetically) And NOT Modified Gravity (at present sophistication) …….

Dark matter detection

DM

DM

SM

SM

New Physics?

Production

Direct Detection

Indirect Detection

Indirect Detection of WIMP

through their annihilation products

Signals high-energy neutrinos, anti-protons, positrons & photons

Sources Sun, Earth, Galactic Center, Milky Way Halo, Stars, External Galaxies

HE neutrinos from Sun/Earth or anomalous γ-rays peaks (E,θ) smoking gun signatures

Anomalous spectral distributions of e+, p-bar, γ etc. dependent on background models

Anomalous Cosmic Positron Spectrum

！ Consolidated by latest results from PAMELA, Fermi

Background

PAMELA

Astrophysical Primary sources or WIMP-induced ??

Fermi

But !! ATIC e-Excess Not Confirmed by Fermi-LAT & HESS

HESS (Air Cerenkov

Telescope)

PPB-BETS

ATIC

Fermi

AMS-2 Sensitivities …

PAMELA-09

… charge determination till ~500 GeV May 16, 2011

WIMP Direct Detection

Elastic recoil of non relativistic halo WIMPs off the nuclei

Both Spin-Independent (~A2) and Spin-Dependent [~(J+1/J) ] Couplings

Recoil energy of the nucleus in the keV range Annual modulation effect due to the rotation of the

Earth around the Sun Directional Recoils, experimentally challenging

December

60° June

WIMP-detection Experiments Worldwide (from Subject Review TAUP-07)

SUF CDMS I

LiF Elegant V&VI

IGEX

Gran Sasso DAMA/LIBRA CRESST I/II Genius TF CUORICINO XENON WArP

CanFranc IGEX ROSEBUD ANAIS

LSM EDELWEISS I/II

Boulby NaIAD ZEPLIN I/II/III DRIFT 1/2

Soudan CDMS II

XMASS KIMS

ORPHEUS

FNAL COUPP

SNOLAB Picasso DEAP SuperCDMS

ArDM

DUSEL LUX CLEAN SIGN

Cryogenic (<77K) Experiments

Running

TEXONO

Target

CRESST II

CDMS II, EDELWEISS I

Light

1% energy fastest no surface effects

Phonons/heat

100% energy slowest cryogenics

Ionization 10% energy

WIMP

WIMP

ZEPLIN-I, DEAP, CLEAN, XMASS

CDMS II, EDELWEISS II

Ephonons

E lig

ht

Ephonons

E ion

izat

ion

HPGe expts

DAMA/LIBRA KIMS

Picasso, Simple, Coupp (superheated)

ZEPLIN II/III/Max, XENON, LUX, WARP, ArDM

Detector Techniques - Present Focus : Nuclear Vs Electron recoils

Future : Lower Threshold ; Direction Sensitive

DAMA/LIBRA NaI(Tl) Scintillator at Gran

Sasso : total 0.29+0.87 ton-year data

Observe annual modulation in the 2-6 keV single-hit signal band, total 11 cycles, > 8σ

No modulations at higher energy & for multiple-hits

2-6 keV

6-14 keV

2-6 keV

6-14 keV

Annual Modulation in single hit at 2-6 keV

No Modulation for multiple hits at 2-6 keV

No Modulation for single hit above 6 keV

multiple- hits residual rate (green points) vs single-hit residual rate (red points)

Single-Hit Power Spectrum

612 kg-days

Dominated by Surface

Background

X 33

Two Maxima

Threshold ~ 8 keV(NR)

Measure: photons & ionization

±

48 kg X 100.9 days

P0=31% ⇒ No WIMP Signal

Spin-Independent σ(χΝ) Exclusion Plot

TEXONO-CDEX Collaboration TEXONO [since 1997] : Neutrino Physics at Kuo-Sheng Reactor Neutrino

Laboratory (KSNL) Taiwan (AS, NTHU, INER, KSNPS) Turkey (METU) India (BHU)

CDEX [birth 2009] : Dark Matter Searches at China Jin-Ping

Underground Laboratory (CJPL) China (THU, CIAE, NKU, SCU,EHDC)

Taiwan EXperiment On NeutrinO

China Dark Matter EXperiment

Research Program: Low Energy Neutrino and Dark Matter Physics

32

• 28 m from core#1 @ 2.9 GW • Shallow site : ~30 mwe overburden • ~10 m below ground level

Kuo Sheng Reactor Neutrino Laboratory :

Configuration: Modest yet Unique

Flexible Design: Allows different detectors conf. for different physics

Inner Target Volume

Front View (cosmic vetos, shieldings, control room …..)

νN Coherent Scattering

Dark Matter Searches (PRD-RC09)

Neutrino Properties & Interactions at Reactor mass quality Detector requirements

1 counts / kg-keV-day

Threshold ~ 100 eV

Magnetic Moments (PRL03,PRD07)

Standard Model νe Scattering (2 ⊗ PRD10)

Current Research Theme:

“sub-keV” Ge Detectors

Physics Goals for O[100 eV threhold⊕1 kg mass⊕1 cpkkd] detector : νN coherent scattering Low-mass WIMP searches Improve sensitivities on neutrino magnetic

moments Implications on reactor operation

monitoring Open new detector window & detection

channel available for surprises

4X5g ULEGe

TEXONO-CDEX : ULEGe & PCGe @ KSNL & CJPL

500g PCGe

900g PCGe

Threshold & Efficiencies & Background for 20g ULEGe (2007)

Dark Matter Searches Analysis

sub-keV Background : ＊ Not fully explained with

conventional background modeling

＊ Intense work on hardware, software and data taking at new underground site

ULEGe ( 5 g × 4) @ KS

CRESST-I @ GS

E ( keV )

Even

t kg

-1 k

eV-1

day

-1

HPGe-1 kg @ KS

CoGeNT(2008)

50% @ 220 eV

Limits (PRDRC09) & Projected Sensitivities on Low Mass WIMPs

CoGeNT 2010 (PRL11: limits & allowed region) / CoGeNT 2011 (PRL11: 2.8σ annual modulation)

intense theoretical interest and speculations on low-mass WIMPS

2400+ m rock overburden, drive-in road tunnel access 6X6X40 m cavern constructed [THU & EHDC] CDEX-TEXONO Dark Matter Program Started ; Panda-

X Experiment under preparation

DUSEL 4850

DUSEL 7400

CJPL

~2400 m

~8750 m

Physics Today September 2010 6 m (H) X 6 m (W) X 40 m (L)

CDEX-TEXONO PandaX

Good Supporting Infrastructures

Campsite #1 Campsite #2

Road from Xichang (西昌)

Tunnel Entrance

ASIDE: View of Satellite Launch Site at Xichang

THU-EHDC MoU 2009/5/8

CJPL Excavation 2009/7— 2010/4

Inauguration Ceremony 2010/12/11

Civil Engineering Completed 2010/6/12

CJPL Hall A: Research Commissioning

Started Sept 27, 2010.

6 m (H) X 6 m (W) X 40 m (L)

1 m thick PE House

Internal space: 8mX4.5mX4m(H)

Data Taking in CJPL – since Feb 2011

20cm 20cm

20cm 20cm Copper

4x5g ULEGe

1kg PCGe

Group A Group B

µ

PS039

PS022

PS025

PS023

PS038

PS026

Cosmic Ray Telescope

First Triple Coincidence Event

Date: 2010/12/02

Time: 04:49:19

First Data Taking : ~ 6 events / [ month - 1 m2 ]

(c.f. ~100 Hz / m2 at sea-level ) Consistent with expectations

+ Measurements of ambient radioactivity (γ’s, neutrons, radon) underway

Summary & Outlook

Missing Energy Density Problem is the most intriguing & important one in basic science.

Some tangible leads & lines of attack already exist for Dark Matter Problem.WIMPs & Axions are popular candidates for Cold Dark Matter, motivated independently in Particle Physics

Wide spectrum of experimental techniques pursued Several anomalous results which can be CDM-induced TEXONO/CDEXcompetitive results in low-mass WIMPs

with sub-keV detectors; New Underground Lab. @ China. Strong Potentials for Surprises in both Theory &

Experiments

Lines of Attack to Look for Surprises:

Explore large dynamic range, look everywhere experimentally available irrespective of theoretical preferences

Study background very carefully to look for anomalies Study detection channels other than χN-elastic Explore BSM astrophysics models Explore different experimental conditions (e.g. crystal

Vs amorphous)

Recall discovery of neutrino oscillations : small Vs large mixing angles atmospheric neutrinos being irreducible

background to proton decay.