XENON10: Searching For Dark Matter with a Noble Liquid TPC

1. RWTH Aachen Graduate College – Bad Honnef XENON10: Searching For Dark Matter with a Noble Liquid TPC Aaron Manalaysay Dept. of Physics, University of Florida August 31, 2006

2. OVERVIEW • Background • Detection • Using Liquid Xenon • UFXenon • XENON10

3. BACKGROUND Cosmic Microwave Background Galactic rotation curves Big Bang Nucleosynthesis Gravitational Lensing D. Clowe, et al , astro-ph / 0608407 Evidence and Motivation

4. BACKGROUND Content of the Cosmos

5. BACKGROUND In equilibrium: X + X Y + Y Thermal Relics from Freezout Leaving equilibrium as universe expands:

6. BACKGROUND Some Properties of Dark Matter • Distributed in spherical halo throughout galaxy • Electrically neutral • Non-relativistic (“cold”) • Weak cross section • Non-baryonic Candidate: WIMP (Weakly Interacting Massive Particle)

7. DETECTION c-c annihilation c-q scattering c + c q + q c + q c + q WIMP Detection Scheme 0-50 keV nuclear recoils

8. DETECTION WIMP interactions: expected 5-50 keV nuclear recoils

9. Using LXe Why Xenon? • Intrinsic Scintillator • Large target nuclei (z=54, a~130-ish) • Easily scaled up in mass • Inert gas: safe and easy to work with (and obtain) • Easy Cryogenics at ~180K • Suitable for spin-dependent and spin-independent WIMP interactions • No long-lived radio isotopes • Self-shielding • Allows for nuclear recoil discrimination

10. Using LXe Er Rel. Scintillation Yield 5.5 MeV alphas 56.5 keV n-recoils 122 keV gammas Ionization yield from alphas Aprile et al. Interaction Process Ionization Xe++e- +Xe Xe2+ Excitation +e- Xe* Xe**+ Xe +Xe Xe2* 178nm Triplet (27ns) 178nm Singlet (3ns) Nevis Lab data 2Xe 2Xe S. Kubota et al.

11. Using LXe PMT PMT e- e- e- Inelastic (80keV+NR) Inelastic (40keV+NR) Nuclear recoils Dual Phase TPC GXe Anode Grid Es Gate Grid e- Ed LXe Cathode

12. UFXenon UFXENON Detector Design

13. UFXenon Counts Energy [keV] Monte Carlo simulations Simulated energy spectrum and position info. Need to simulate light collection efficiency. Ba133 Ba133 g

14. UFXenon q gammas neutrons Studying Nuclear Recoils LXe n AmBe Study nuclear recoils down to 5keV recoils. Absolute recoil energy inferred from recoil angle and ToF. EJ301

15. UFXenon Ionization yield Scintillation and Ionization Yields These measurements are essential for performing nuclear recoil discrimination.

16. UFXenon Lopes et al Additional Scintillation Efficiency Measurement Preliminary data from Lopes et al indicates possible departures from the predictions of the Hitachi model.

17. XENON XENON Collaboration Brown University RWTH Aachen / University of Florida Rick Gaitskell, Peter Sorensen, Luiz de Viveiros, Simon Fiorucci Laura Baudis, Joerg Orboeck, Jesse Angle, Aaron Manalaysay Case Western Reserve University Laboratori Nazionali del Gran Sasso Tom Shutt, Alexander Bolozdyna, Paul Brusov, John Kwong, Eric Dahl Francesco Arneodo, Alfredo Ferella Lawrence Livermore National Laboratory Universidade de Coimbra Adam Bernstein, Norm Madden, Celeste Winant, Chris Hagmann Jose Matias, Joaquim Santos, Luis Coelho Columbia University Yale University Rice University Elena Aprile, Karl Giboni, Masaki Yamashita, Guillaume Plante, Maria Monzani Dan McKinsey, Richard Hasty, Angel Manzur, Taritree Wongjirad, Kaixuan Ni Uwe Oberlack, Roman Gomez, Peter Shagin

18. XENON10 Gran Sasso CDMSII (current) XENON10 XENON100 XENON1T XENON10, 100, 1T Lead Shield

19. XENON10 XENON10

20. XENON10 XENON10 Background MC Simulations

21. XENON10 Current Status/Future Plans • Energy threshold ~10 keV • First data (post shield construction) was dominated by Kr contamination (~25ppm) • Replaced with Xe of low Kr (<1ppm) for calibration (the current status) • Neutron calibration starting in September • Fill with ultra-low Kr level Xe (<1ppb) in September/October • Low-background data Corno Grande, Gran Sasso