LZ and Direct Dark Matter Detection Kimberly J. Palladino February 14, 2017
What is the universe made of? Abell 2218 Reconciling what we measure on Earth with what we see in the cosmos 2
Outline Dark Matter Evidence and Models Direct Detection Overview Liquid Noble Detection LUX Experiment LZ Experiment What UW Madison does 3
Standard evidence 2dF Survey data Bullet cluster red: hot gas blue: dark matter 4
What We Know Isotropy, homogeneity, flat universe, dark energy, cold dark matter, big bang, inflation Local Dark Matter density: 0.3 GeV/cm 3 5
WIMPs Particles with masses of ~100 GeV and interactions at the weak scale would give current dark matter density of.3 GeV/cm 3 6 WIMPs fit naturally with SuSY: lightest neutralino, the LSP
Searching for WIMPs Direct (Scattering) Indirect (Annihilation) X? X Collider (Production) SM SM 7
Direct Detection Needs Ability to see low energy WIMP induced recoils Radiogenically pure Low threshold (< 10s kev) Ability to distinguish nuclear recoils Difference between electronic recoils & nuclear recoils Difference between alphas and nuclear recoils Position reconstruction and fiducialization Shielding from radiogenic and cosmogenic backgrounds 8
Searching for WIMPs (Xe, (D)Ar) (Xe, (D)Ar, NaI) ZEPLIN II, III XENON 10, 100, 1T LUX, LZ PANDA-X DarkSide Scintillation few% energy deposited ZEPLIN I XMASS DEAP-3600 DAMA/LIBRA DM-Ice, KIMS, SABRE (Ge, Si, C 3 F 8, CS 2 ) COGENT, DAMIC DMTPC DRIFT ~20% energy deposited Ionization Nuclear Recoil Only (CF 3 I, C 4 F 10, C 2 ClF 5 ) PICO, COUPP, PICASSO, SIMPLE CRESST II (CaWO 4 ) (Ge, Si) CDMS EDELWEISS Phonons ~100% energy deposited CRESST I (Al 2 O 3 ) 9
Direct Detection Techniques 10
Direct Detection Signals? CRESST-II Cerulli IDM 2012 DAMA/LIBRA Aalseth et al. arxiv:1401.3295 Angloher et al. arxiv:1109.0702 COGENT CDMS-II Si J. Collar IDM 2012 Agnese et al. arxiv:1304.4279 11
Liquid Xenon TPCs Ionized and excited states Primary Scintillation (S1) with some recombination and de-excitation in the liquid Ions drift in TPC electric field Amplification region in gas creates proportional light (S2) S2/S1 provides particle ID Events are hundreds of microseconds (set by electron drift velocity) Strong position reconstruction 12
Xenon: Electron Recoil Xenon, electron recoil Xe Xe + Ion Xe2 + Ionized molecule e - e - e - S2 Recombination Xe Xe VUV photons 175nm Xe* Xe2* Xe Excitation Heat S1 Branching ( ) sketched for electron recoils 13 cartoons from Akerib and Shutt
Xenon: Nuclear Recoil Xenon, nuclear recoil Xe Xe + Ion Xe2 + Ionized molecule e - e - e - S2 Recombination Xe Xe VUV photons 175nm Xe* Xe2* Xe Excitation Heat S1 Branching ( ) sketched for nuclear recoils 14 cartoons from Akerib and Shutt
LUX results 15
Energy Calibration: Doke Plot Electron recoils with energy dependent varying recombination Total quanta remain, W=13.7 ev S1 [phd] = [0.1167 ± 0.003] nγ S2 [phd] = [12.05 ± 0.83 ] ne 16
Electronic Recoils Inject gas source of tritiated methane Tritium populates the background model Utilizes energy scale from the Doke plot 17
Nuclear Recoils Mono energetic D-D Neutron beam (2.45 MeV) Double scatters kinematically give energy of first scatter for charge yield Single scatters studied for light yield 18
Events 19
Spin Independent Result 20
Direct Detection Coming of Age Mature computing framework and simulations Including evaluation of simulation tools Benchmarking fundamentals Reflectivity, scattering and absorption lengths Developing designs and procedures Cleanliness, materials handling Detector reliability and automation Likelihood analyses Full operator treatment of interactions 21
LUX to LZ 22
LZ @ SURF Davis Cavern 1480 m (4200 m water equivalent) Sanford Underground Research Facility Homestake Gold mine Lead, SD (near Deadwood) 23
LZ design 7 tonne active mass liquid Xe TPC, 10 tonnes total Instrumentation conduits Existing water tank Liquid Xe heat exchanger Gadolinium-loaded liquid scintillator Outer detector PMTs Cathode high voltage feedthrough Neutron beampipe Nelson - Collaboration CD3 IPR at LBNL - January 10-12, 2017 24 11
TPC design SECTION VIEW OF LXE TPC GAS PHASE AND ELECTROLUMINESCENCE REGION Top PMT array Side Skin PMTs TPC field cage Anode Gate LXe surface Weir troug Skin PMT HV CONNECTION TO CATHODE Bottom PMT array Cathode grid Reverse-field region Side skin PMT mounting plate 25
LZ Backgrounds NR ER n ER NR Kr/Rn β decay N tion CD3 IPR at LBNL - January 10-12, 2017 tion CD3 IPR at LBNL - January 10-12, 2017 External Materials Uniform in LXe 26
Cold and Pure LXe Ex-situ removal of Kr via charcoal chromatography Constant removal of reactive impurities with a hot gas getter, flows at 500 slpm Gas circulation allows for injection of radioactive calibration sources Kr83m, Xe131 workhorses CH3T quarterly; must be removed with getter 27
LZ Projected Limit 28
LZ Signal Region 40 GeV WIMP 29
LZ @ UW Madison 30
Simulations 31
LXe Handling 12 32
SLAC System Test Platform 33
System Test TPC Test Grid High Voltage with single photon and single electron sensitivity Prototype many subsystems: circulation, slow controls, sensors 34
Coming Soon In 2017: DEAP-3600 XENON 1T 35
LZ = LUX + ZEPLIN 38 Institutions, 217 People Black Hills State University Brookhaven National Laboratory (BNL) Brown University Fermi National Accelerator Laboratory (FNAL) Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) Lawrence Berkeley National Laboratory (LBNL) Lawrence Livermore National Laboratory (LLNL) Northwestern University Pennsylvania State University SLAC National Accelerator Laboratory Center for Underground Physics (Korea) South Dakota School of Mines and Technology Imperial College London (UK) South Dakota Science and Technology Authority (SDSTA) LIP Coimbra (Portugal) STFC Rutherford Appleton Laboratory (RAL) MEPhI (Russia) Texas A&M University STFC Rutherford Appleton Laboratory (UK) University at Albany (SUNY) University College London (UK) University of Alabama University of Michigan University of Bristol (UK) University of California (UC), Berkeley University of Rochester SUPA, University of Edinburgh (UK) University of California (UC), Davis University of South Dakota University of Liverpool (UK) University of California (UC), Santa Barbara University of Wisconsin-Madison University of Oxford (UK) University of Maryland Washington University in St. Louis University of Sheffield (UK) University of Massachusetts Yale University Nelson - Collaboration CD3 IPR at LBNL - 36 January 10-12, 2017 1
Conclusion LUX has presented world-leading limits with the most sophisticated dark matter analysis to date. Direct Dark Matter Detection is entering a new era of discovery capability, along with a more mature detector design and collaboration organization LZ will be the most sensitive to conventional ~100 GeV WIMPs, as well as being a versatile detector for other exotic searches The broad dark matter field, with collider, indirect, and direct detections will have interesting results over the next 7= 2pi years UWMadison is a great place to be working on LZ! 37