S. Fiorucci – Brown University

The LUX Dark Matter SearchStatus Update

Sixth TPC Symposium – Paris – December 17th, 2012

Exciting times in South Dakota

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The LUX Collaboration

Richard Gaitskell PI, ProfessorSimon Fiorucci Research AssociateMonica Pangilinan PostdocJeremy Chapman Graduate StudentCarlos Hernandez Faham Graduate StudentDavid Malling Graduate StudentJames Verbus Graduate Student

Brown

Thomas Shutt PI, ProfessorDan Akerib PI, ProfessorMike Dragowsky Research Associate ProfessorTom Coffey Research AssociateCarmen Carmona PostdocKaren Gibson PostdocAdam Bradley Graduate StudentPatrick Phelps Graduate StudentChang Lee Graduate StudentKati Pech Graduate StudentTim Ivancic Graduate Student

Case Western

Bob Jacobsen PI, ProfessorVictor Gehman ScientistDavid Taylor EngineerMia ihm Graduate Student

Lawrence Berkeley + UC Berkeley

Adam Bernstein PI, Leader of Adv. Detectors GroupDennis Carr Mechanical TechnicianKareem Kazkaz Staff PhysicistPeter Sorensen Staff PhysicistJohn Bower Engineer

Lawrence Livermore

Xinhua Bai PI, Professor

SD School of Mines

James White PI, ProfessorRobert Webb ProfessorRachel Mannino Graduate StudentClement Sofka Graduate Student

Texas A&M

Mani Tripathi PI, ProfessorRobert Svoboda ProfessorRichard Lander ProfessorBritt Hollbrook Senior EngineerJohn Thomson Senior MachinistMatthew Szydagis PostdocRichard Ott PostdocJeremy Mock Graduate StudentJames Morad Graduate StudentNick Walsh Graduate StudentMichael Woods Graduate StudentSergey Uvarov Graduate Student

UC Davis

University of Maryland

Carter Hall PI, ProfessorAttila Dobi Graduate StudentRichard Knoche Graduate Student

Frank Wolfs PI, ProfessorWojtek Skutski Senior ScientistEryk Druszkiewicz Graduate StudentMongkol Moongweluwan Graduate Student

University of Rochester

Dongming Mei PI, ProfessorChao Zhang PostdocDana Byram Graduate StudentChris Chiller Graduate StudentAngela Chiller Graduate Student

University of South Dakota

Daniel McKinsey PI, ProfessorPeter Parker ProfessorJames Nikkel Research ScientistSidney Cahn Lecturer/Research ScientistAlexey Lyashenko PostdocEthan Bernard PostdocMarkus Horn PostdocBlair Edwards PostdocScott Hertel PostdocKevin O’Sullivan PostdocNicole Larsen Graduate StudentEvan Pease Graduate StudentBrian Tennyson Graduate Student

Yale

LIP Coimbra

Isabel Lopes PI, ProfessorJose Pinto da Cunha Assistant ProfessorVladimir Solovov Senior ResearcherLuiz de Viveiros PostdocAlexander Lindote PostdocFrancisco Neves PostdocClaudio Silva Postdoc

UC Santa Barbara

Harry Nelson PI, ProfessorMike Witherell ProfessorDean White EngineerSusanne Kyre EngineerCurt Nehrkorn Graduate Student

Henrique Araujo PI, Senior LecturerTim Sumner ProfessorAlastair Currie Postdoc

Imperial College London

Chamkaur Ghag PI, Lecturer

University College London

Alex Murphy PI, ReaderJames Dobson PostdocLea Reichhart Graduate student

University of Edinburgh

Collaboration Meeting, UCSB March 2012

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The LUX Experiment

Top PMT array

Bottom PMT array

Inner cryostatOuter cryostat

Thermosyphon

PTFE reflector panels and field cage

Copper shield

Anode grid

Cathode grid

Water tank

Detector stand

• 370 kg xenon• 300 kg active region• 100 kg fiducial

• 122 PMTs 2” round• Low-background Ti cryostat

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Water Tank: d = 8 m, h = 6 m300 tonnes, 3.5 m thickness on the sidesInverted steel pyramid (20 tonnes) under tank

to increase shielding top/bottom

Cherenkov muon veto

Ultra-low background facilityGamma event rate reduction: ~10-9

High-E neutrons (>10 MeV): ~10-3

2.75 m

1.20 m

3.50 m

Inverted steel pyramid

Slide design from L de Viveiros

Rendering by J. Thomson

0 1 2 3 4Shield Thickness (m)

Rock g

mneutrons

Rock neutrons

LUX Design – Water Tank

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LUX Design – Deep Underground OperationCosmic Rays - Muons

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LUX Design – Self-shielding

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LUX – XENON100 Comparison

Comparison of LUX and XENON100 data for the same exposure of 7600 kg.d, from the latest XENON100 result (July 2012). LUX data is simulated from known radioactive background components. The WIMP signal in red corresponds to a 100 GeV/c2 WIMP with a cross-section at the current best sensitivity limit of 2.5 10-45 cm2. The ER background is one order of magnitude lower, allowing for a clearer detection signal or a stronger limit.

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The LUX Program

2007 – 2009 2010 – 2011 2012+

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Surface Lab – June 2009 to September 2010

Full-scale test of LUXdeploymentLiq/gas systemPMT testingDAQ testingWater shieldXe purity

June 2009 September 2010

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Surface Lab – August 2010 to February 2011

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Surface Lab – May 2011 : Run 1

Cryogenic Test: Success!

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Surface Lab – July to October 2011

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Surface Lab – October 2011 to February 2012 : Run 2

Position resolution < 5mm

205 ms ~ 25 cm = ½ a LUXLeak!

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LUX Run 2 Summary

List of major achievements already communicated to the World by February 2012

To which one can add: Working slow-control and alarm system, working muon veto, emergency storage system in place, working calibration system (external and internal), reviewed and tested operating and assembly procedures, no (work related) injuries over 17 months and > 38,500 total work hours…

Negative points: Leak in condenser line limited purification capability (easily fixed) One PMT base stopped working (out of 122; now fixed) Used ~20-30 kg more Xenon to fill detector than anticipated (we have a lot to spare now) Drift field limited by flaws on Cathode grid wires (now replaced and tested) Did not find Dark Matter (neither did anyone else… probably)

120 V / cm (limited by electroluminescence on grid)

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Surface Lab – March to July 2012

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Sanford Lab – Davis Laboratory

Clean Room

Control Room LN Storage

Counting FacilityXe Balloon

Gas System

Electronics

Cherenkov Water tank

LUX Detector

Breakout

Excavation/construction started August 2009finished June 2012

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July 12

Davis Campus – Summer 2012

June 15

July 6

June 25

June 29

August 25

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Davis Campus – September 2012

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LUX Underground Physics Program

Oct 22 – Nov 7: Water Tank filled with water

Oct 1 – Dec 6: Detector at vacuumCherenkov data from PMT windows, PTFE

Dec 7 – Jan 13: Detector warm with Xe gasAlpha events from Rn on internal surfacesKr-83 for gas flow tomography

Jan 14 – Feb 13: Cool-down + Condense Xe400 kg of Xe with 5 ppt measured Kr is ready

~1 month to reach acceptable Xe purity

~2 months of non-blind WIMP searchIncluding run parameters optimization

~1 month of additional calibrations

First result by mid-2013

PTFE Cherenkov events

October 22

Nov 7

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LUX WIMP Sensitivity Goal

XENON100 2011

XENON100 2012

LUX 300 days

Edelweiss II 2011ZEPLIN III 2011 CDMS II 2008

= LUX 15 days

= LUX 4 days

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Additional SlidesBecause this was not long enough already…

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LUX Design – Dual Phase Xenon TPC

Can measure single electrons and photons

Charge yield reduced for nuclear recoils

Excellent 3D imagingReject multiple scattersEliminate edge events to take

advantage of Xe self shielding

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Born from the joining of LUX and ZEPLIN

Construction 2014-2016

Run 2016- 2019 (…?)

New features compared to LUXIncreased Xe mass : 7t total, 5t fiducial482 3" PMTs at ~1 mBq radioactivity levelLiquid Scintillator shield/vetoInstrumented « dead » Xe spaceImproved Cherenkov veto coverage

...That’s it. Progress in sensitivity comes chiefly with:Increasing the Xe massScaling up existing LUX technologyXe self-shielding is driving the background rates down dramatically

R&D effort ramping up since 2011, Project Management through LBNL

LZ Program – Overview

LZ uses the same water tank as LUX in the Davis Lab

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LZ Program – WIMP Sensitivity Reach

XENON100 2012

LUX 300 days

LZ 1000 days

x 7

x 175