Large Scale Searches for Relic Dark Matter Mani Tripathi - - PowerPoint PPT Presentation

Mani Tripathi, Jan 2010

Large Scale Searches for Relic Dark Matter

Mani Tripathi

University of California, Davis January 21, 2010

Aspen Particle Physics Winter 2010

Mani Tripathi, Jan 2010

Rick Gaitskell

Direct DM Search - Progress & Breakthroughs

XENON 10 Year

Mani Tripathi, Jan 2010

This review focuses on highly scalable technologies using liquid targets.

• 1. Liquid Xenon
• 2. Liquid Argon/Neon
• 3. Other

Xenon10, Xenon100, Xenon1T, MAX … ZEPLIN-I, ZEPLIN-II, ZEPLIN-III LUX-350, LUX-ZEPLIN @Sanford (LZS) , LZ@DUSEL (LZD) Mini-CLEAN, DEAP, CLEAN … WArP DarkSide, MAX COUPP, COUPP-60, COUPP-Tonne Scale

Mani Tripathi, Jan 2010

Target Comparison -- WIMP Nucleus Elastic Scattering

Recoil Spectra A2 Dependence Higher sensitivity for Xe for Recoil Energy < 20 keV. Favored regime for Ar for Recoil Energy > 40 keV.

Mani Tripathi, Jan 2010

Estimate of Target Sensitivities

Target Energy Threshold * / assumed signal acceptance Fiducial Mass required for 25 WIMP events in 100 live- days †† Total number of ER events in Fiducial Mass for 100 live- days ** Max acceptable leakage in ER Rejection Xe TPC 2 keVr / 80% 100 kg 17 0.05 Ar (†) 40 keVr / 90% 1.5 tonnes 2 x 108 5 x 10-9 Ar (†) 80 keVr / 90% 6.5 tonnes 8 x 108 1 x 10-10 Ge (CDMS) 10 keVr / 50% 350 kg 2 x 105 5 x 10-6

Assume 100 GeV, 4x10-45 cm2.

Akerib, Gaitskell et al

Assume natural Ar.

Mani Tripathi, Jan 2010

Why Noble Liquids?

Very powerful Self- shielding. Effective when size > attenuation length => ~20 cm buffer for Xe => Fiducial Mass > 100 kg.

Mani Tripathi, Jan 2010

Two Signal Technique

Interaction

EGC Cathode

Grids Anode

EAG > EGG > EGC

Gas phase PMT Array

Time Time

Primary (S1) Secondary (S2)

e e-

• e

e-

• e

e-

• e

e-

• e

e-

• e

e-

• e

e-

• e

e-

• e

e-

• e

e-

• e

e-

• e

e-

• 0–350 µs

depending

• n depth

~40 ns width

~1 µs width

Liquid phase

EAG EGG

Mani Tripathi, Jan 2010

γ/neutron Discrimination

XENON 10

Differences in recombination efficiency is exploited to discriminate between electron and nuclear recoils. Figure of merit derived from plots of: Log (charge escaping recombination/total primary light produced) … Next slide.

Mani Tripathi, Jan 2010

Calibration Data (Prototype Xe Cell at Case Western)

Recoil Energy (keVr) Recoil Energy (keVr)

133Ba Electrons 252Cf Neutrons

These measurements were made above ground, but agree well with Xenon10 experience.

Mani Tripathi, Jan 2010

Simulated Signal in LUX 350

300 days acquisition 100 kg fiducial mass Electron recoil background ~2.6x10-4 dru (based on screening of materials)

Mani Tripathi, Jan 2010

Power of self-shielding

XENON10 Data -- 5.4 kg, 59 days LUX Simulation -- 100 kg, 100 days Red points are for a simulated signal

• f 100 GeV WIMP and a cross

section 5x10-45 cm2. Open points are for 25 kg fiducial.

Mani Tripathi, Jan 2010

The CLEAN Program

Thanks to Dan McKinsey Switch to talk about Argon and COUPP and return to Xenon

Mani Tripathi, Jan 2010

Mani Tripathi, Jan 2010

Mani Tripathi, Jan 2010

Mani Tripathi, Jan 2010

The WArP Program

Thanks to Cristiano Galbiati

Mani Tripathi, Jan 2010

WArP being installed in its Cryostat 12/18/08

Mani Tripathi, Jan 2010

Mani Tripathi, Jan 2010

DarkSide Program

Thanks to Cristiano Galbiati

DarkSide

UMass Amherst Arizona State University Augustana College Black Hills State University Fermilab University of Houston University of Notre Dame Princeton University Temple University UCLA

• dual-phase TPC
• 50 kg active mass
• 5 ph.el/keVee
• 23 keVr threshold
• background-free for 3 yrs
• sensitivity 10-45 cm2

First test for three technological advances crucial to achieve zero background:

• depleted argon
• QUPIDs at LAr temp
• active liquid scintillator neutron veto

DarkSide-50

Princeton Prototype Plant for Industrial Scale Production News: NSF funding (NSF PHY-0811186) Achieved 1.5 kg/day (depletion >25), goal ~few kg/day in 2010

Mani Tripathi, Jan 2010

The COUPP Program

Thanks to Juan Collar

Mani Tripathi, Jan 2010

Mani Tripathi, Jan 2010

COOUPP Approach

Insensitive to MIP, γ and β Spin-1/2 19F provides sensitivity to spin dependent cross section Main background from a-decays A 60 kg detector is built and being commissioned in a test facility To be deployed at SNOLab

Mani Tripathi, Jan 2010

Juan Collar HEPAP Presentation

Mani Tripathi, Jan 2010

The XENON Program

Thanks to Elena Aprile

31

Willhelms Universität Münster Max-Planck-Institut für Kernphysik Universität Zürich Laboratori Nazionali del Gran Sasso Jiao Tong University Shanghai Waseda University ~50 scientists from 10 institutions: University of California Los Angeles Rice University Houston Columbia University New York Universidade de Coimbra Subatech Nantes

Rafael F. Lang (Columbia): Search for Dark Matter with XENON 37

80 PMT bottom array 98 PMT top array veto PMT bell 170kg liquid xenon PTFE TPC, field shaping veto PMT

• 16000V

+5000V

XENON100: first results by Spring 2010

XENON100: operational at LNGS

1400 m Rock (3100 mwe) XENON100

65

XENON Sensitivity Projections

spin-independent interaction:

66

XENON Sensitivity Projections

pure spin-dependent neutron coupling:

Mani Tripathi, Jan 2010

The ZEPLIN Program

Thanks to Tim Sumner

Mani Tripathi, Jan 2010

ZEPLIN - I

5kg LXe target (3.1kg fid) 3 PMTs Cu construction Polycold cryogen cooling

ZEPLIN - II

31kg LXe target (7.5kg fid) 7 PMTs Operated stably for long runs

ZEPLIN - III

8 kg fiducial target 31 PMTs

UK Collaboration Edinburgh, ICL, RAL, Sheffield International Collaborators Coimbra, ITEP, Rochester, Texas A&M, Torino, UCLA

Mani Tripathi, Jan 2010

ZEPLIN - III

Mani Tripathi, Jan 2010 ZEPLIN-III Results with spin-independent limits – Lebedenko et al., arXiv:0812.1150 (2008) Note: XENON10 limit is single- sided and only at 85% confidence!

Tim Sumner

• Nov. 2009

Mani Tripathi, Jan 2010 ZEPLIN-III Spin-dependent limits – Lebedenko et al., arXiv:0901.4348 (2009)

Spin-dependent Results

Mani Tripathi, Jan 2010

ZEPLIN-III future plans

• Veto installation (plastic + Gd) - done
• PMT upgrade – b/g 1/30 - done
• Calibration – about to start
• Physics Exploration
• Second science run (~10-8pb)

Mani Tripathi, Jan 2010

The LUX/LZ Program

Mani Tripathi, Jan 2010

LUX At Sanford Lab

Mani Tripathi, Jan 2010

• 99.3 – 99.9% Electron Recoil background rejection for 50%

Neutron Recoil acceptance, in the range 5 keVr < E < 25 keV

LUX Goals

• γ + β rate < 8 x 10-4

events/kg/keVee/day with 99.4% rejection (conservative)

• 10 month run w/ 50% NR

acceptance (net 15,000 kg-days)

• DM reach σ ~ 4x10-46 cm2

(Equivalent to an event rate of ~0.4/100kg/month in 100kg fiducial)

(SuperCDMS Goal @ SNOLab: Gross Ge Mass 25 kg (x 50% fid) for 1000 days running) Edelweiss I ZEPLIN II CDMS II WARP LUX (2010)

CDMS II@Soudan (2008)

SuperCDMS@SNOLab (2013)

XENON10

SuperCDMS@Soudan (2009)

Edelweiss I

Mani Tripathi, Jan 2010

• Internal Gammas strong self-

shielding against PMT activity (main source). Double Compton scatters are rejected.

• Internal Neutrons (α,n) & fission <<

γ + β. ~65% double scatter. External γ + Neutrons shield with veto for cavern n, and HE neutrons from muon.

Mani Tripathi, Jan 2010

Detector - aspect ratio ~1.2

• 350 kg Dual Phase liquid Xe TPC
• 60 PMTs (Hamamatsu R8778) each in top and bottom arrays
• ~100 kg achievable in the fiducial volume

Active Water Shield

The LUX detector

Mani Tripathi, Jan 2010

Davis Cavern

Mani Tripathi, Jan 2010

De-watering Milestone -- LUX hopes to be underground in Fall 2010.

Mani Tripathi, Jan 2010

Mani Tripathi, Jan 2010

Mani Tripathi, Jan 2010

Future Program: Scaling Up

Mani Tripathi, Jan 2010

LZS LZD

Mani Tripathi, Jan 2010

Summary

• A diverse and vibrant program in direct search for Dark Matter is

around the corner. Complementary to the LHC searches.

• The new generation detectors like Xenon100 and LUX will

surpass current best limits in <1 week of running.

• If WIMP Dark Matter exists x10 below current limits, discovery is

within reach in the next year or two.

• Design efforts are underway to design even larger detectors for

the DUSEL era. If WIMPs are not detected down to 10-48 cm2, there will be serious need for new models for Dark Matter.