1. Status of EXO-200 Carter Hall, University of Maryland DUSEL town meeting November 4, 2007

2. 2 ИТЭФ ITEP

3. 3 A liquid xenon TPC as a  0 detector Monolithic TPC design has optimal surface area to volume ratio Full three dimensional event reconstruction Fluid can be purified in situ Noble gas isotope enrichment relatively easy and safe No crystal growth No long-lived xenon isotopes to activate

4. 4 The Centerpiece of EXO-200 200 kg of xenon enriched to 80% in 136 Xe: the most isotope in possession by any  0 collaboration. 11 times larger than previous experiments.

5. 5 EXO-200: the first 200 kg  0 experiment 200 kg of Liquid Xenon to be contained in copper vessel, surrounded by 50 cm of ultra pure cryofluid inside a copper cryostat and shielded by 25 cm of lead. Copper liquid xenon vessel HFE-7000 cryofluid copper cryostat lead shielding

6. 6 1 2 3 EXO-200 is housed in a 100 class clean room three of six modular clean rooms EXO clean rooms assembled at Stanford Refrigerators hold the cryostat at liquid xenon temperature

7. March 30, 2007: commissioning of cryogenics and fluid handling Refrigeration feedthrus HFE feedthru Insulating vacuum pump-out Liquid xenon supply line Liquid xenon return line 24 hour shifts for two months. First cooldown of 4 tons of HFE-7000. First xenon liquefaction for EXO-200. Dummy LXe vessel

8. Summer 2007: cleanrooms being seperated at Stanford

9. Summer 2007: moving the experiment underground

10. 10 Underground site is the WIPP facility in Carlsbad, NM A salt mine for storage of radioactive waste.... and for low radioactivity experiments!

11. Fitting the cleanroom into the “waste hoist” – one ¼” to spare!

12. EXO-200 underground at WIPP – September 2007 Cleanrooms expected to be fully operational in mid November. Plan to re-commission cryogenics in February.

13. Thin (1.5 mm) copper liquid xenon vessel minimizes radioactivity, but it can’t withstand a large pressure differential. Inner cryostat door copper liquid xenon vessel Xenon pressure and HFE pressure must be controlled to maintain no more than a 5 psi pressure difference across the xenon vessel. Liquid xenon inside HFE outside

14. Low Background Liquid Xenon Vessel Under Construction Each part made from ultra-pure copper Finished part Vessel made by e-beam welding

15. 15 charge drift direction The EXO-200 detector: a dual TPC cathode field shaping rings crossed wire planes and avalanche photodiodes

16. teflon light reflectors flex cables on back of APD plane (copper on kapton, no glue) field shaping rings (copper) acrylic supports LAAPD plane (copper) and x-y wires (photo-etched phosphor bronze) Central HV plane (photo-etched phosphor bronze) ~40 cm x-y crossed wires, 60 o

17. 17 Crossed wire planes and APD array measure event energy and position y-position given by induction signal on shielding grid. x-position and energy given by charge collection grid. APD array observes prompt scintillation to measure drift time.

18. 18 1 kV/cm Liquid xenon data show an anti-correlation between ionization and scintillation ~570 keV Bi-207 source Energy resolution: 3.0% @ 570 keV or 1.4 % @ Q(  Factor of two better than most recent Xe experiment

19. 19 TPC wire grids produced by photoetching Charge collection with photoetched wire grids Wires connected in gangs-of-three to reduce channel count

20. Scintillation detected by Avalanche Photodiodes Gang-of-seven APDs EXO-200 will have 259 APDs in each half of the detector Copper APD holder Triply redundant electrical connections made by photoetched “spider”

21. 21 EXO-200 Case 186133 Majorana mass (meV) QRPA 1 NSM 2 40 Radioactive Background (events) 6.4*10 25 1.6 * 2700.2 T 1/2 0ν (yr, 90%CL) σ E /E @ 2.5MeV (%) Run Time (yr) Eff. (%) Mass (ton) Sensitivity of EXO-200 Improves on previous 136 Xe experiments by one order-of-magnitude, and competitive with the best  0 experiments in the world. HM and IGEX ( 76 Ge): ‹m  › < 340 meV 1 EXO-200 will also make the first observation of  2 in Xe-136. 1) Rodin, et. al., Nucl. Phys. A 793 (2007) 213-215 2) Caurier, et. al., arXiv:0709.2137v1