Strategies for the Detection of Dark Matter What do we know? What - - PowerPoint PPT Presentation

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Strategies for the Detection of Dark Matter What do we know? What - - PowerPoint PPT Presentation

Dec 15, 2022 104 likes •342 views

Bernard Sadoulet Dept. of Physics /LBNL UC Berkeley UC Institute for Nuclear and Particle Astrophysics and Cosmology (INPAC) Strategies for the Detection of Dark Matter What do we know? What have we achieved so far? Entering interesting

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 1

Strategies for the Detection of Dark Matter

Bernard Sadoulet

  • Dept. of Physics /LBNL UC Berkeley

UC Institute for Nuclear and Particle Astrophysics and Cosmology (INPAC)

What do we know? What have we achieved so far?

Entering interesting domain

Strategies for the future

Exciting new technologies => zero background experiments cross checking each other + consistency with LHC

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 2

Standard Model of Cosmology

  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future

Ωmatter ΩΛ

A surprising but consistent picture

Non Baryonic Dark Matter

Ωm >> Ωb = 0.047 ± 0.006 from Nucleosynthesis WMAP

Not ordinary matter (Baryons) Mostly cold: Not light neutrinos≠ small scale structure

mv < .17eV Large Scale structure+baryon oscillation + Lyman α

+ internally to WMAP

Ωmh2 ≠ Ωbh2 ≈15 σ's

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 3

Ongoing Systematic Mapping

  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future

Most baryonic forms excluded (independently of BBN, CMB) Particles: well defined if thermal (model dependent when athermal) Additional dimensions?

thermal Light Neutrinos WIMPs non baryonic exotic particles non-thermal Axions Wimpzillas baryonic gas VMO dust

clumped H2?

Mirror branes Energy in bulk

Primordial Black Holes ?

Λ Quintessence

dark matter and energy

?

SuperWIMPs

MACHOs

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 4

Standard Model of Particle Physics

Fantastic success but Model is unstable

Why is W and Z at ≈100 Mp? Need for new physics at that scale supersymmetry additional dimensions

Flat: Cheng et al. PR 66 (2002) Warped: K.Agashe, G.Servant hep-ph/0403143

In order to prevent the proton to decay, a new quantum number => Stable particles: Neutralino Lowest Kaluza Klein excitation

QCD violates CP

Dynamic stabilization by a Peccei-Quinn axion?

Gravity is not included and we do not understand vacuum energy

Always the danger of a failure of General Relativity and that dark matter is part of a new set of “epicycles” that we invent to adjust theory to increasingly accurate data

  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future
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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 5

  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future

Generic

Particles in thermal equilibrium + decoupling when nonrelativistic

Cosmology points to W&Z scale Inversely standard particle model requires new physics at this scale (e.g. supersymmetry or additional dimensions) => significant amount of dark matter

Weakly Interacting Massive Particles

Freeze out when annihilation rate ≈ expansion rate ⇒ Ωxh2 = 3⋅10-27cm3 / s σ Av ⇒ σ A ≈ a2 M

EW

2

Particle Cosmology

Bringing both fields together: a remarkable concidence 2 generic methods: Direct Detection= elastic scattering Indirect: Annihilation products

γ ’s e.g. 2 γ ’s at E=M is the cleanest ν from sun &earth ≈ elastic scattering dependent on trapping time e+, p

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 6

Direct Detection

dn/dEr Er Expected recoil spectrum

Elastic scattering

Expected event rates are low (<< radioactive background) Small energy deposition (≈ few keV) << typical in particle physics Signal = nuclear recoil (electrons too low in energy) ≠ Background = electron recoil (if no neutrons)

Signatures

  • Nuclear recoil
  • Single scatter ≠ neutrons/gammas
  • Uniform in detector

Linked to galaxy

  • Annual modulation (but need several thousand events)
  • Directionality (diurnal rotation in laboratory but 100 Å in solids)
  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future
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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07

Experimental Approaches

7 CRESST I CDMS EDELWEISS CRESST II ROSEBUD ZEPLIN II, III XENON WARP ArDM SIGN NAIAD ZEPLIN I DAMA XMASS DEAP Mini-CLEAN DRIFT IGEX COUPP

Scintillation Heat - Phonons Ionization

Direct Detection Techniques

Ge, Si Al2O3, LiF !"#$%&'()$ *+#$%&',-.$/ 0 NaI, Xe, Ar, Ne Xe, Ar, Ne Ge, CS2, C3F8

~100% of Energy ~20% of Energy Few % of Energy

At least two pieces of information in order to recognize nuclear recoil extract rare events from background (self consistency) + fiducial cuts (self shielding, bad regions)

  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future

A blooming field

As large an amount of information and a signal to noise ratio as possible

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 8

Phonon Mediated Detectors

  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future

Target crystal

Principle: Detect lower energy excitations

15 keV large by condensed matter physics standards

Goals

  • Sensitivity down to low energy

Phonons measure the full energy

  • Active rejection of background: recognition of nuclear recoil

Combine with low field ionization measurement e.g. CDMS I and II EDELWEISS

  • r photon (CRESST II)

6.5 cm

But: operation at very low temperature!

ex: CDMS I 1999

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07

CDMS II

  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future

Q inner Q outer A B D C Rbias I bias SQUID array Phonon D Rfeedback Vqbias

7.5cmØ Ge or Si disk 1cm thick @ 35mK Athermal Phonons + ionization

=> large amount of information

Qinner Qouter

z y x

2 ionization signals (inner detector, guard) 4 phonons: Risetime and delay with respect ionization => 3D position of the event In particular, in spite of “folding”, proximity to the surface ≠ surface electrons

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07

CDMS II Discrimination

  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future

Phonon risetime and charge to phonon delay for further discrimination

Yield

Risetime (µs)

n Surface electrons γ n γ Surface electrons Ionization/Recoil energy

Ionization yield

Recoil Energy Surface Electrons

Essential to fix the cuts totally Blind

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 11

In Situ Calibrations

1.5 1.0 0.5 0.0

Yellow points: nuclear recoils induced by a 252Cf neutron source Blue points: electron recoils induced by a 133Ba γ source Recoil Energy (keV)

10 20 30 40 50 60 70 80 90 100

23x our WIMP-search background

Calibration data, prior to timing cuts

Ionization Yield Z2/Z3/Z5/Z9/Z11 Ionization Yield

Recoil Energy (keV)

After timing cuts

53% acceptance of neutrons

10 20 30 40 50 60 70 80 90 100

Z2/Z3/Z5/Z9/Z11

1.5 1.0 0.5 0.0

  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future
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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 12

WIMP-search data

Prior to timing cuts

Z2/Z3/Z5/Z9/Z11 Ionization Yield

Recoil Energy (keV)

0 10 20 30 40 50 60 70 80 90 100 1.5 1.0 0.5 0.0

10.4 keV Gallium line

1 candidate (barely)

After timing cuts, which reject most electron recoils

ESTIMATE: 0.37 ±0.15(stat.) ± 0.20(sys.) electron recoils, 0.05 recoils from neutrons expected

1 near-miss

Z2/Z3/Z5/Z9/Z11 Ionization Yield

Recoil Energy (keV)

0 10 20 30 40 50 60 70 80 90 100 1.5 1.0 0.5 0.0

  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future

90 kg.days 34kg.days after cuts

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 13

Scalar couplings

CDMS II (2005)

Zeplin-I result in doubt astro-ph/0512120 Increasing tension with DAMA who claims a signal (NaI) Ellis et al 2005 CMSSM Entering in interesting territory

  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future

See PRL 96 (2006) 011302

10 times more sensitive than any other experiment

Adding 1st Soudan run, 53kg.day-> 19kg.day after cut Total 53 kg.day after cut

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 14

Goals: Cover Supersymmetry

10-45 cm2 next step

25-100kg

Ultimate 10-47 cm2

2-8 tons ≈ No background! World-best limit today CDMS II 2007 SuperCDMS Phase C 1000 kg of Ge SuperCDMS 25kg 25 kg of Ge 2011 SuperCDMS Phase B 150 kg of Ge ZEPLIN I EDELWEISS

ZEPLIN II goal

XENON 10

DAMA

10-45 cm2 10-47cm2 10-46cm2

  • 1. What do we know
  • 2. What has been achieved?
  • 3. Strategies for the future
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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 15

Why 1 Zeptobarn ≡ 10-45 cm2

  • 1. What do we know
  • 2. What has been achieved?
  • 3. Strategies for the future

χ2

0 , χ1 ±

Coannihilation

Bulk (5 < tan β < 45) Focus Point (tan β~10) Stau Coannihilation (tan β ~ 10) Higgs Funnel (50 < tan β < 60)

µ>0

LHC can access low cross section but fine tuning

The Higgs funnel and stau coannihilation are fine tuned to enhance annihilation

Bulk region is accessible both to LHC and Direct Detection

Rich physics in region of overlap (stability, couplings)

10-45cm2 is a natural scale Direct Detection can access readily Focus region

LHC has trouble above 350GeV/c2

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 16

Strategies for the Future

Lessons from CDMS & Edelweiss Search for rare events requires maximum amount of information

Large signal/noise =>efficient cut and identification of background ≠ threshold detectors (Simple, Picasso, COUPP)

– which can play useful role however for rapid exploration of large masses

Active discrimination of the background event by event:

  • > zero background

≠ Statistical methods (cf. DAMA, ZEPLIN I)

≥ 2 promising technologies with

Phonon mediated detectors” phonons +ionization/scintillation Liquid Noble Gases:Scintillation pulse shape +ionization Other ideas: high pressure gas

Several experiments with different technologies/targets

Beware: “A background may hide another one” R&D at real scale Importance of the physics requires cross checks Interesting science in target comparison ≈A2

  • 1. What do we know
  • 2. What has been achieved?
  • 3. Strategies for the future
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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 17

Phonon mediated detectors

  • 1. What do we know
  • 2. What has been achieved?
  • 3. Strategies for the future

Current technology capable to go to 25kg region

Super CDMS 25kg -> 10-45cm2 EDELWEISS II, CRESST II -> EURECA CDMS=large background rejection margin

Significant change of production testing methods -> 1 Ton

Surface events Nuclear recoils

Used for PRL06 analysis Current methods

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07

Noble Liquids 1

18

  • 1. What do we know
  • 2. What has been achieved?
  • 3. Strategies for the future

but 39Ar, radial resolution (Rayleigh scattering +few photons)

Neutrons in lab Needed ≠39Ar

Recent breakthrough

Triplet killed in nuclear recoils

  • D. McKinsey
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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 19

Liquid Noble Gases 2

  • 1. What do we know
  • 2. What has been achieved?
  • 3. Strategies for the future

“Xenon 10”:

≈ 10kg taking data: results soon!

Complex phenomenology

Neutron Elastic Recoil 40 keV Inelastic (129Xe) + NR 80 keV Inelastic (131Xe) + NR

Another breakthrough: extraction of electrons from liquid Zeplin II(result), Zeplin III XMASS 2 phases

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 20

WARP : 2.6kgAr ionization +

scintillation + pulse shape Astro-ph/0701286 WARP prototype 97 kg days No blind (1 event at 54 keV) But energy scale?

Scintillation yield still high 80%->60% Neutron recoil looks too steep @60keV

140kg module in fabrication

Liquid Noble Gases results

  • 1. What do we know
  • 2. What has been achieved?
  • 3. Strategies for the future

Zeplin II

ZEPLIN II

37kg Xe ionization + scintillation

Astro-ph/0701858 1767 kg days->225 kg days Background limited: Leakage from Gammas (poor S2/S1 resolution from poor photon collection) Rn on internal teflon reflector(radial cut ineffective at low E) Result totally dependent on subtraction (Gaussian assumption)

Excellent progress. Encouraging Calibration + understanding of complex phenomenology Leakage from low signal/noise

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 21

Conclusions

Essential to detect Dark Matter

A key ingredient of the standard model of cosmology At least show it is not an epicycle! WIMPs is the generic Thermal model

Well defined roadmap for WIMP searches Elastic scattering

  • 10-45cm2 identifying event by event nuclear recoil

Phonon mediated detectors can do it (e.g.SCDMS 25kg) +tests Noble Gas

  • 10-46-47cm2 Need large mass, zero background technologies

Liquid noble gases appears to be best complement to phonon mediated det,

When we have a discovery: link to galaxy (low pressure TPC≈5000 m3 )

Interesting role of indirect detection

GLAST could be an interesting smoking gun: High energy neutrino from sun as probe of p spin dependent

Importance

Instrumentation (high information content) ≥2 technologies (Technical risk, Cross check, A2 dependence) Take full advantage of complementary information (LHC,GLAST,HE solar v’s)

  • 1. What do we know?
  • 2. What has been achieved?
  • 3. Strategies for the future

WARP 140kg in

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B.Sadoulet Strategies for the Detection of Dark Matter KEK 6 Feb 07 22

CDMS II

Funded by NSF and DOE