XENON Dark Matter Project Alexandre grandchamp Antoine baillod

Agenda • Why Dark Matter (DM) ? • What do we know from theory and possible candidates • Signal characteristics • Possible detectors • The XENON experiment: how, where, when… • XENON results • Other applications

Indirect evidence of DM Galaxy M 33 • Source: Wikipédia, Galaxy rotation curve

Source: Wikipédia, Galaxy rotation curve

What do we know ? •

Annual modulation • Angle ~60° • Flux modulation. Maximum in june, minimum in december • Directional event Source : K. freese, M. Lisanti, C. Savage. Annual Modulation of Dark Matter : A Review. 2013

Interaction with baryonic matter • PHONONS • Cryogenic detector • WIMPS excitate the lattice -> phonons • Event can be studied from the phonon • SCINTILLATION • IONIZATION • Energy deposited in nucleus • WIMPS kicks out an electron • Re-emitted with a photon • Electron detected via current • Detect the photon with a photomultiplier

Experiments Source: T. Saab, An Introduction to Dark Matter Detection Searches & Techniques, 2012

XENON – HOW DOES IT WORK? • WIMP interacts with a Xe nucleus • Photon emitted by scintillation and detected with PMT (S 1 signal) • Electron extracted with electric field • Emits photons by proportional scintillation (S 2 signal) Design and Performance of the XENON 10 Dark Matter Experiment, The Xenon Collaboration, January 2010

BRIEF HISTORY XENON 100 • 2006 -2007 • • 89 PMTs • 15 kg of LXe • Cylinder of diameter 20 cm and 15 cm high 2008 -2012 98 PMT on top 80 PMT on the bottom 64 PMT around the veto volume 165 kg of Lxe (62 kg in the target region) Cylinder of diameter 30 cm and 30 cm high

INTEREST OF XENON • Highest A among the noble elements • High density • Almost no radioactive isotopes • LXe and LAr both reacts by scintillation and ionisation when radiated • Modest boiling point (165 K at 1 atm) • Allows distinction between electron and nuclear recoils • Fast decay times for excited states (~10 ns)

BACKGROUND ISOLATION - SHIELDING Shielding. Gran Sasso lab: 1 mile (as 3 km of water) underground. Water: stops neutrons. Lead (20 cm), copper (5 cm): stops gammas The Xenon Dark Matter Project, xenon. astro. columbia. edu, consulted the 20 th march 2017

BACKGROUND ISOLATION - SHIELDING • Blue – stainless steel • Yellow – copper • Magenta – PTFE to reflect the scintillation photons • Orange -PMTs The XENON 100 Detector for Dark Matter Searches, A. Kish, 2009

BACKGROUND ISOLATION – DISCRIMINATION • Most radiation is eliminated by shielding • Most radiation interacts with electrons • Distinction between recoils with the ratio S 1/S 2 • Neutrons interacts by nuclear recoil • Distinction using the veto volume to detect multiple interactions

XENON RESULTS • No WIMP event identified • Improvement on the upper limit of the WIMP-nucleon cross-section • XENON 10: 10− 43 cm 2 for a 30 Ge. V/c 2 WIMP mass • XENON 100: 2. 0 × 10− 45 cm 2 for a 65 Ge. V/c 2 WIMP mass Source: T. Saab, An Introduction to Dark Matter Detection Searches & Techniques, 2012

WHAT’S NEXT? XENON 1 T • 3, 5 tons of Lxe • 1 ton of target volume • 121 PMT at bottom, 127 on top • 84 PMT around the 700 m 3 water tank • aims for a 2. 0 x 10− 47 sensitivity cm 2 for the cross section Physics reach of the XENON 1 T dark matter experiment, The Xenon collaboration, April 2016

Bibliography • S. Tarek, An Introduction to Dark Matter Direct Detection Searches and Techniques, 2012 • Design and Performance of the XENON 10 Dark Matter Experiment, The Xenon Collaboration, January 2010 • The Xenon Dark Matter Project, xenon. astro. columbia. edu, consulted the 20 th march 2017 • Physics reach of the XENON 1 T dark matter experiment, The Xenon collaboration, April 2016 • The XENON 100 Detector for Dark Matter Searches, A. Kish, 2009