1 / 17

SNOLAB and EXO

SNOLAB and EXO. David Sinclair SNOLAB Workshop August 2005. EXO. Search for double beta decay using Xe Identify decay energy by ion detection Control background by tagging events with Ba daughter 200 kg separated isotope liquid Xe prototype under construction – will be installed at WIPP.

aerona
Download Presentation

SNOLAB and EXO

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SNOLAB and EXO David Sinclair SNOLAB Workshop August 2005

  2. EXO • Search for double beta decay using Xe • Identify decay energy by ion detection • Control background by tagging events with Ba daughter • 200 kg separated isotope liquid Xe prototype under construction – will be installed at WIPP

  3. Canadian participation in EXO • Carleton/Laurentian groups • 7 Canadian faculty • First R&D funding in April • Role clarified in July collaboration meeting

  4. Xe offers a qualitatively new tool against background: 136Xe 136Ba++ e- e- final state can be identified using optical spectroscopy (M.Moe PRC44 (1991) 931) Ba+ system best studied (Neuhauser, Hohenstatt, Toshek, Dehmelt 1980) Very specific signature “shelving” Single ions can be detected from a photon rate of 107/s 2P1/2 650nm 493nm 4D3/2 • Important additional • constraint • Huge background • reduction metastable 80s 2S1/2

  5. Possible Gas Version • Gas counter would allow tracking • Better rejection of gamma backgrounds • Single site criteria • Two Bragg peak criteria • Possibly better energy resolution • Better prospects for in situ Ba tagging

  6. Liquid Advantages • Smaller active volume • Easier shielding • No high pressure containment • Canadian groups will develop Gas Option

  7. Objectives • To demonstrate a feasible concept for a gas phase Xe detector for bb decay • If successful, to build a 200 kg prototype • If really successful, expand to tonne scale

  8. Possible concept for a gas double beta counter Anode Pads Micro-megas WLS Bar Electrode Blue/red laser ->->->->->->->->->->->->->->->->->->->-> Wire cathode WLS Bars For 200 kg, 10 bar, box is 1.5 m on a side

  9. Issues – Energy Resolution • Need to demonstrate ~1% or better • What gain mechanism to use? • Micromegas? • What gas additives to use? • Quench gas? • Drift velocity? • WLS for 178 nm light? • Loss of 178 nm light? • TMAE or other to convert light to electrons? • What is the optimal pressure?

  10. Issues - Tracking • Want to identify decay vertex • Want to see 2 Bragg peaks • Want to reject multi-site events • Eventually want to look and angular correlation

  11. Issues – Ba tagging • Need to demonstrate a robust Ba tagging scheme • Demonstrate Ba+ livetime • Demonstrate Ba++ -> Ba+ conversion • Measure Ba tagging efficiency • Demonstrate low false tagging probability

  12. Engineering • Much larger volume suggests water shielding to get purity • Look at thin gas containment, high pressure water, use cavern to contain pressure

  13. Programme – Energy Resolution • Explore TPC energy resolution in Xe w/wo optical detection – Carleton/Laurentian/Neuchatel+Saclay? • Optimize micromegas • Explore gas mixtures • Explore scintillation detection

  14. Programme - Tracking • Carleton • Initially need MC study • Look at impact of magnetic fields

  15. Programme – Ba Tagging • Carleton/Laurentian/Colorado • Ba line widths • Ba lifetime • Tagging schemes • Demonstrate reliable, in-situ tagging • Study backgrounds • Note – Line widths -> high laser power, need selective detection • Toy Model – Pulse blue laser, look for blue light when laser off, use fluorecene (peak absorption 490 nm, emission 520 nm, 97% Quantum yield, 80,000 /mol/cm absorption) + bialkali PMT

  16. Programme • Do studies of energy resolution in small test cell at Carleton (~1 year) • Do MC studies and optimize tracking (~1 year) • Develop laser lab for Barium counting at SNOLAB • Build ~30 cm test chamber to operate underground at SNOLAB to demonstrate full concepts including trigger, tracking, tagging (use 134Cs to simulate decay) • Develop 200 kg prototype to be ready in ~3 years when liquid prototype tests complete at WIPP

  17. Schedule • Aim to have a concept in 1 year • 1% energy resolution • Demonstrated tagging • Conceptual design for vessels, shielding • Demonstrate concepts with 30 cm chamber in 2 years • Start construction of 200 kg detector in cavern capable of expansion to tonne scale in 3 years

More Related