Dark Matter Detection with XENON0 Accomplishments, Challenges and the Future http://xenon.astro.columbia.edu Kaixuan Ni Columbia University TeV Particle Astrophysics IHEP, Beijing, Sep.4-8, 008
The Challenges for Direct DM Detection WIMP Scattering Rates R M det M χ ρσ v Rate [evts/kevr/kg/day] -5 18 evts/0-kg/year (E th =5 kevr) 8 evts/0-kg/year (E th =15 kevr) Xe (A=131) Ge (A=73) Ar (A=40) large mass (ton scale) low energy threshold (a few kev) background suppression deep underground -6 M χ = 0 GeV, σ χ p = 45 cm passive shield low intrinsic radioactivity -7 0 0 30 40 50 60 70 80 Recoil Energy [kevr] gamma background discrimination
World Wide Dark Matter Searches Yangyang KIMS Homestake LUX SNOLAB DEAP/CLEAN PICASSO Boulby ZEPLIN DRIFT? Kamioka XMASS Soudan CDMS Frejus/ Modane EDELWEISS Gran Sasso CRESST DAMA/LIBRA WARP XENON 3
The Noble Liquid Revolution Noble liquids (LAr, LXe) are relatively inexpensive, easy to scale up Self-shielding reduce external background Excellent gamma background rejection (pulse-shape, or ionization/scintillation) XMASS 800-kg Single Phase (XMASS, CLEAN/DEAP) WARP Two Phase (XENON,ZEPLIN II/III,WARP,ArDM,etc.) 4
Two-phase Xenon Detectors for Dark Matter Detection WIMPs/Neutrons Top PMT Array nuclear recoil Gammas electron recoil 5
Signals from XENON S1 S S1 S 6
XENON WIMP Search Data 136 kg-days Exposure= 58.6 live days x 5.4 kg x 0.86 (ε) x 0.50 (50% NR) (data collected between Oct.006 and Feb.007) ~1800 events Statistical leakage from electron recoil band Anomalous events due to non-active Xe 4.5 7 kevr noise event WIMP Search Window 7
XENON WIMP-Nucleon Cross-Section Upper Limits Spin-independent Phys. Rev. Lett. 0, 01303 (008) Spin-dependent, pure neutron coupling Phys. Rev. Lett. 1, 091301 (008) CDMS II XENON CDMS ZEPLIN-II XENON (NO BKG SUBTRACTION) 8.8 x -44 cm at 0 GeV 4.5 x -44 cm at 30 GeV Constrained Minimal Supersymmetric Model (NO BKG SUBTRACTION) 6 x -39 cm at 30 GeV 8
the phased XENON dark matter search program the past (006-007) the current (007-009) the future (009-013) XENON XENON0 XENON1T 9
The XENON0 Collaboration LNGS Collaboration Meeting, July 15,008 Columbia University Elena Aprile(Spokesperson), Bin Choi, Karl-Ludwig Giboni, Kyungeun Elizabeth Lim, Antonio Jesus Melgarejo, Kaixuan Ni, Guillaume Plante, Taehyun Yoon Rice University Uwe Oberlack, Yuan Mei, Marc Schumann, Peter Shagin University of California, Los Angeles Katsushi Arisaka, Hanguo Wang, David Cline, Ethan Brown, Artin Teymourian Gran Sasso National Laboratory, Italy Francesco Arneodo, Serena Fattori University of Coimbra, Portugal Jose A Matias Lopes, Joao Cardoso, Luis Coelho, Joaquim Santos University of Zurich Laura Baudis, Ali Askin, Alfredo Ferella, Marijke Haffke, Alexander Kish, Roberto Santorelli, Eirini Tziaferi
Laboratori Nazionali del Gran Sasso, Italy LNGS 1400 m Rock (30 w.m.e) XENON0 LVD ICARUS OPERA
XENON0 Underground at the Laboratori Nazionali del Gran Sasso LNGS: 1.4km rock (30 mwe) XENON0 XENON XENON0 outside shield XENON0 inside shield XENON 1
13 1 XENON0: The Status TPC of Assembly XENON0: the TPC Assembly the 170 kg LXe (70 kg target)
14 16 XENON0: The PMTs 4 PMTs (Hamamatsu R850-06-Al ) 1 square metal channel developed for XENON Low radioactivity (<1 mbq U/Th per PMT) 80 PMTs for bottom array (33% QE) 98 PMTs for top array (3% QE) 64 PMTs for top/bottom/side Veto (3% QE) Bottom Array Top Array PMTs for Side & Bottom Shield PMT Base
XENON0 Material Screening 15
XENON0 Current Status data MC Evts/keVee/kg/day 1-1 xe0_08060_018 edge events with poor light collection, will be removed by radial position cut all single/multiple scattering events Rate [evts/kg/day/kev] 1-1 XENON0 MC Background all single/multiple scattering events - - single scatter only with ~46 kg fiducial mass cut -3 0 500 00 1500 000 500 3000 S1 [kevee] -3 0 500 00 1500 000 500 3000 E [kev] Detector has been fully filled with liquid xenon. First Measured background Spectrum in good agreement with MC prediction! 16
XE0: First Light & Charge Signals (Cs137) Current effort: Liquid Xenon is continuously purified to achieve better purity 17
XE0: First Light & Charge Signals (Cs137) Cs137 zero field.6 pe/kev Current effort: Liquid Xenon is continuously purified to achieve better purity 17
Kr removal process was finished on Sep.4. Currently we are taking data to verify the Kr concentration in Xe. Less than 50 ppt Kr/Xe expected. ~7 ppb before Kr removal process 18
XENON0 Background Prediction from Simulation Avg Rate 0-0 kev (Cryostat, PMTs, Bases) Z [mm] z [mm] 0-50 -0-150 -00-50 -300 0 0 40 60 80 0 10 140 r [mm] r [mm] 1-1 - -3 evts/kev/kg/day] -3 bkg rate [mdru = 1-1 0 0 30 40 50 60 70 Fiducial Mass [kg] 1-1 Exposure Time with Zero Bkg [month] different fiducial volume cuts (spherical vs cylindrical) to achieve the best bkg rate vs fiducial mass ~6 mdru for a fiducial mass of 40 kg (no gamma background for 3 months) ~ mdru for a fiducial mass of 0 kg (no gamma background for 1.5 year) 19
XE0 sensitivity projection ] (90% C.L. upper limit) [cm "!-p -43-44 -45 XENON0 Sensitivity Projection for 0 GeV WIMPs Current Best Limit 30 kg x 7 month (zero bkg) ~Aug 009 signal discovery sensitivity 0 5 15 0 5 Exposure Time with Zero Bkg [month] 1 ) cm -44 = "!-p Expected # of WIMP Events ( XENON0 experiment can probe down to -45 cm, but also has great discovery potential! 0
XENON1T - the ultimate dark matter detector Explore the full region in CMSSM space New design with full coverage of ultra-low background photodetectors and cryostat Need a deeper underground lab (or efficient muon veto) and larger space Larger International Collaboration To be proposed for 009-013 Total project cost: estimate ~$0M 1
The Road to Direct DM detection: from XENON0 to XENON1T ] (90% C.L. upper limit) [cm "!-p -4-43 -44-45 -46-47 XENON Sensitivity Projection - 0 GeV WIMPs XENON0 XENON1T 009 0 011 01 0 5 15 0 5 30 35 40 45 50 Exposure Time with Zero Bkg [month] 1 ) cm -44 = "!-p Expected # of WIMP Events ( -1 -
The Road to Direct DM detection: from XENON0 to XENON1T ] (90% C.L. upper limit) [cm "!-p -4-43 -44-45 -46-47 XENON Sensitivity Projection - 0 GeV WIMPs XENON0 XENON1T 009 0 011 01 0 5 15 0 5 30 35 40 45 50 Exposure Time with Zero Bkg [month] 1 ) cm -44 = "!-p Expected # of WIMP Events ( -1 - Cross-section [cm ] (normalised to nucleon) -40-4 -44-46 -48 0808160941 XENON (007) XENON0 Projected (009) WIMP Mass [GeV/c ] http://dmtools.brown.edu/ Gaitskell,Mandic,Filippini CDMS (008) SuperCDMS Projected (01) XENON1T Projected (01) 1 3
The Road to Direct DM detection: from XENON0 to XENON1T ] (90% C.L. upper limit) [cm "!-p -4-43 -44-45 -46-47 XENON Sensitivity Projection - 0 GeV WIMPs XENON0 XENON1T 009 0 011 01 0 5 15 0 5 30 35 40 45 50 Exposure Time with Zero Bkg [month] 1 ) cm -44 = "!-p Expected # of WIMP Events ( -1 - Cross-section [cm ] (normalised to nucleon) -40-4 -44-46 -48 0808160941 XENON (007) XENON0 Projected (009) WIMP Mass [GeV/c ] http://dmtools.brown.edu/ Gaitskell,Mandic,Filippini CDMS (008) SuperCDMS Projected (01) XENON1T Projected (01) 1 3 Two-Phase Xenon is currently the most promising technology for DM detection
The Road to Direct DM detection: from XENON0 to XENON1T ] (90% C.L. upper limit) [cm "!-p -4-43 -44-45 -46-47 XENON Sensitivity Projection - 0 GeV WIMPs XENON0 XENON1T 009 0 011 01 0 5 15 0 5 30 35 40 45 50 Exposure Time with Zero Bkg [month] 1 ) cm -44 = "!-p Expected # of WIMP Events ( -1 - Cross-section [cm ] (normalised to nucleon) -40-4 -44-46 -48 0808160941 XENON (007) XENON0 Projected (009) WIMP Mass [GeV/c ] http://dmtools.brown.edu/ Gaitskell,Mandic,Filippini CDMS (008) SuperCDMS Projected (01) XENON1T Projected (01) 1 3 Two-Phase Xenon is currently the most promising technology for DM detection XENON0 is currently the largest two-phase xenon detector under operation
The Road to Direct DM detection: from XENON0 to XENON1T ] (90% C.L. upper limit) [cm "!-p -4-43 -44-45 -46-47 XENON Sensitivity Projection - 0 GeV WIMPs XENON0 XENON1T 009 0 011 01 0 5 15 0 5 30 35 40 45 50 Exposure Time with Zero Bkg [month] 1 ) cm -44 = "!-p Expected # of WIMP Events ( -1 - Cross-section [cm ] (normalised to nucleon) -40-4 -44-46 -48 0808160941 XENON (007) XENON0 Projected (009) WIMP Mass [GeV/c ] http://dmtools.brown.edu/ Gaitskell,Mandic,Filippini CDMS (008) SuperCDMS Projected (01) XENON1T Projected (01) 1 3 Two-Phase Xenon is currently the most promising technology for DM detection XENON0 is currently the largest two-phase xenon detector under operation Let s hope we will see WIMPs in 009!