Noble Travails: LUX @ Sanford Lab
http://luxdarkmatter.org
Rick Gaitskell, Joint Spokesperson, LUX Collaboration
Particle Astrophysics Group, Brown University, Department of Physics (Supported by US DOE HEP) http://particleastro.brown.edu
Gaitskell / Brown University 23 years in dark matter
CDMS II: Winter @Soudan Minnesota
PHYSICS ITALIAN Sanford Lab STYLE XENON10 LUX @Homestake, @ Gran Sasso South Dakota
Gaitskell / Brown University Dark Matter Underground Searches - Silver Jubilee •First publication on an underground experimental search for cold dark matter (Ahlen et al. 1987. PLB 195, 603-608). http://www.pnnl.gov/physics/darkmattersymp.stm
Dark Matter Searches Rick Gaitskell, Brown University, LUX / DOE 1986 operating a 0.8 kg Ge ionization • 33 kg-days detector at Homestake Mine, SD (adjacent to Ray Davis’s operating Solar Neutrino Experiment)
1 cts/keVee/kg/day
Dark Matter Searches Rick Gaitskell, Brown University, LUX / DOE LUX 1 min Dark Matter Searches: Past, Present & Future
−40 200 kg fid., 90% NR 10 Edelweiss ’98 Oroville H−M ’94 100 kg fid., 50% NR LUXUKDMC 5 min Homestake −41 H−M ’98 10 IGEX DAMA ’98 DAMA ’00 LIBRA ’08 CDMS I SUF ’99 Edelweiss ’01 ~ 1 event kg−1 day−1 CDMS I SUF ’02 −42 WARP ’07 Edelweiss ’03 10 ZEPLIN I ZEPLIN II
[60 GeV WIMP] CDMSII Soudan ’04 CRESST ’11 2 Ge LUX 18 hrs −43 10 NaI LUX 1 hr Edelweiss ’09 XENON10 Cryodet CDMSII Soudan ’10 Edelweiss ’11 Liq. Noble XENON100 ’10 ZEPLIN III
section cm −44
− CS2 10 XENON100 ’11 Projected LUX 4 days Signal SuperCDMS Soudan ’14 −45 XMASS 800kg XENON100 ’12 10
−1 −1 LUX 14 days ~ 1 event 100 kg yr LUX 300kg −46 10 Limit Scalar Cross LUX 300 days −47 10 1985 1990 1995 2000 2005 2010 2015 2020 Year Thanks to Carlos Hernandez Faham (Brown) for work on slides LUX 5 LUX @ Sanford Lab The LUX Collaboration
Brown Richard Gaitskell PI, Professor Simon Fiorucci Research Associate SD School of Mines Monica Pangilinan Postdoc Jeremy Chapman Graduate Student Xinhua Bai PI, Professor Carlos Hernandez Faham Graduate Student David Malling Graduate Student Texas A&M James Verbus Graduate Student Samuel Chang Graduate Student James White PI, Professor Dongqing Huang Graduate Student Robert Webb Professor Rachel Mannino Graduate Student Case Western Reserve Clement Sofka Graduate Student Thomas Shutt PI, Professor UC Davis Dan Akerib PI, Professor Mike Dragowsky Research Associate Professor Mani Tripathi PI, Professor Tom Coffey Research Associate Robert Svoboda Professor Carmen Carmona Postdoc Richard Lander Professor Karen Gibson Postdoc Britt Hollbrook Senior Engineer Adam Bradley Graduate Student John Thomson Senior Machinist Patrick Phelps Graduate Student Matthew Szydagis Postdoc Chang Lee Graduate Student Richard Ott Postdoc Kati Pech Graduate Student Jeremy Mock Graduate Student Tim Ivancic Graduate Student James Morad Graduate Student Nick Walsh Graduate Student Collaboration Meeting, UCSB March 2012 Imperial College London Michael Woods Graduate Student Sergey Uvarov Graduate Student Henrique Araujo PI, Senior Lecturer Tim Sumner Professor UC Santa Barbara Alastair Currie Postdoc Harry Nelson PI, Professor Lawrence Berkeley + UC Berkeley Mike Witherell Professor Dean White Engineer Yale Bob Jacobsen PI, Professor Susanne Kyre Engineer University of Rochester Victor Gehman Scientist Curt Nehrkorn Graduate Student Frank Wolfs PI, Professor Daniel McKinsey PI, Professor David Taylor Engineer Wojtek Skutski Senior Scientist Peter Parker Professor Mia ihm Graduate Student University College London Eryk Druszkiewicz Graduate Student James Nikkel Research Scientist Sidney Cahn Lecturer/Research Scientist Chamkaur Ghag PI, Lecturer Mongkol Moongweluwan Graduate Student Alexey Lyashenko Postdoc Lawrence Livermore Ethan Bernard Postdoc University of South Dakota Adam Bernstein PI, Leader of Adv. Detectors University of Edinburgh Markus Horn Postdoc Dennis Carr GroupMechanical Technician Dongming Mei PI, Professor Blair Edwards Postdoc Kareem Kazkaz Staff Physicist Alex Murphy PI, Reader Chao Zhang Postdoc Scott Hertel Postdoc Kevin O’Sullivan Postdoc Peter Sorensen Staff Physicist James Dobson Postdoc Dana Byram Graduate Student John Bower Engineer Nicole Larsen Graduate Student Lea Reichhart Graduate student Chris Chiller Graduate Student Evan Pease Graduate Student Angela Chiller Graduate Student LIP Coimbra Brian Tennyson Graduate Student Isabel Lopes PI, Professor University of Maryland Jose Pinto da Cunha Assistant Professor Carter Hall PI, Professor Vladimir Solovov Senior Researcher Attila Dobi Graduate Student Collaboration was formed in 2007 and fully funded by Luiz de Viveiros Postdoc Richard Knoche Graduate Student Alexander Lindote Postdoc DOE and NSF in 2008. Francisco Neves Postdoc Claudio Silva Postdoc
LUX 7 LUX Anatomy
Thermosyphon
Titanium Vessels
PMT Holder Copper Plates
Dodecagonal field cage + PTFE reflector panels
• 370 kg (300 kg active) LXe • 122 PMTs (2’’ round) • Low-background Ti cryostat • PTFE reflector cage 2’’ Hamamatsu R8778 • Thermosyphon used for cooling (>1 kW) Photomultiplier Tubes (PMTs)
LUX 8 Xenon Self-shielding Single Scatter Events /keVee/kg/day
It’s quiet in the middle Goal
pp Solar ν,e scattering
• Liquid xenon is a dense target at 3 g/cc. • Self-shielding allows this technology to greatly benefit from scaling up. • We expect ~1 ER in the fiducial volume/dm energy range every 4 days in LUX.
LUX 9 The first 76 days of LUX
Comparing nominally equivalent kg-days for 100 kg LUX fiducial versus 34 kg XENON fiducial but LUX has much greater sensitivity/kg-day because of cleaner signal/fewer BG events
LUX (Monte Carlo) XENON100
arXiv:1104.2549
LUX signal and background expectation for 7,600 kg-days XENON100 7,600 kg-days result for comparison. net exposure. WIMP events assume m = 100 GeV, σ = Note higher ER rate - ~180 events primarily due to 3x10-45 cm2. Assumes 100 kg fiducial. Given very low ER Compton scattering of external gamma background. rate, can significantly increase fiducial in early running.
LUX 10 The LUX Program
LUX0.1 CWRU LUX Surface LUX Underground
2007 - 2009 Oct 2009 - Jun 2012 July 2012+
LUX 11 Example of alpha particle in middle of LUX detector
Bottom PMTs
S2 hit pattern Top PMTs
drift time 220 µs
Time (samples/10ns) x10 Channel 4
LUX 12 Light Collection
Activated xenon Data Fit Data Cs-137 LUXSim Fit LUXSim
164 keV 236 keV (39.6 + 196.6 keV)
• Achieved 8 phe/keVee light collection for 662 keV gammas at the center of the detector, zero field
• The light collection for 122 keV at 500 V/cm is 4 phe/keVee • This is ~x3 as good as XENON100
• PTFE reflectivity in liquid xenon measured to be > 98% at 1-sigma level
LUX 13 Xenon purification
200 µs electron lifetime achieved 2.5 Gammas (Single S2s) EL = 204.5 ± 5.6 µs 2
1.5 S2 / S1
10 1 log
0.5
0 0 50 100 150 200 250 Drift Time [µs]
LUX 14 Beta-Alpha Physics from BiPo
= 164 µs 222 ⌧1/2 3.8 d Rn Qβ = 3.2 MeV ↵ 218 214 210 160 µs 3.1 m Po Po Po 138 dy 214 210 Bi Bi 214 210 206 27 m Pb 20 m Pb 5 d Pb 22 y
Beta range (Emean = 642 keV) Alpha range in LXe is ~1.5 mm in LXe is ~50 µm This coincidence event is highly localized in x,y,z
LUX 15 Sample β-α Bi-Po event in surface data
4 x 10 Pulses < 100 phe not displayed 10 7.5
s S1 S2 5 LUX ↵ S1 2.5 Preliminary phe/ ↵ S2 0
0 50 100 150 200 250 300 350 s
Position reconstruction computed with Zeplin III Mercury algorithm
LUX 16 Statistical position resolution
Bulk Events
20 40 Data Data = 0.77±0.09 cm = 0.091±0.005 cm 15 30
10 20 5 x 10 z 0 0 −6 −4 −2 0 2 4 6 −6 −4 −2 0 2 4 6 214 214 x between 214Bi and 214Po [cm] z between Bi and Po [ s]
25 Data 20 = 0.65±0.08 cm • Alpha S2 signal equivalent to ER gamma 15 S2(z=0) < 20 keVee
10 • The statistical resolution in z is 0.09 cm 5 y 0 The statistical resolution in x or y is 0.7 cm −6 −4 −2 0 2 4 6 • y between 214Bi and 214Po [cm]
LUX 17 LUX Davis Campus @ Sanford Lab “Eager Graduate Students” Davis Cavern, Oct 2011 “Busy Graduate Students” Davis Cavern, Sep 2012 LUX Water Tank - Outside View LUX Water Tank - Inside View LUX+ZEPLIN = LZ
LZ LUX!!!?? 7 tonnes ? x482 3’’ PMTs
300 kg x122 2’’ PMTs
LUX 23 Expected sensitivity 43 Edelweiss II 10 CDMS II ZEPLIN III XENON100 (2012) 44 10 mu > 0 225 day x 34 kg fid. Xe
LUX 300 days x 100 kg fid. Xe 45 mu < 0 10 - goal zero background ] (normalised to nucleon)
2 46 10
47 10 LZ 1000 days x 5 tonne fid. Xe section [cm
- goal zero background Theory from Cheung et. al. 48 arxiv:1211.4873 Cross 10 1 2 3 10 10 10 WIMP Mass [GeV/c2]
LUX 24 •LUX detector moved to from surface lab to underground lab @ Sanford July 2012 All detector/safety system commissioned and checkouts passed Water shield / Muon veto - filled and operational Experiment is working closely with Sanford Lab personnel who are focused on science mission •Dec 2012: Warm Xe gas to perform preliminary checks Internal calibration with 83Kr to check circulation path / data taking •Now: Detector Cooldown and Condensation of 370 kg liquid Xe (low 85Kr<5 ppt) Authorization to proceed from Lab •During 2013 Full checkout of all systems cold / circulation to achieve purity (collection of S2 throughout volume) Calibrations to establish detector response at low energy Unblinded ~2 month run to demonstrate dark matter sensitivity •Ultimate Science Goal is to take 300 days of live data Expect to continue data-taking/calibration studies until the LZ experiment (7 tonnes) is ready to be installed. G2 down select - DOE/NSF is funding LZ development in 2013, will compete in field downselect end 2013
Dark Matter Searches Rick Gaitskell, Brown University, LUX / DOE