an Overview an Overview Giorgio Gratta Giorgio Gratta Physics Dept, Stanford Physics Dept, Stanford DBD09, Waikoloa Hilton, Oct 12, 2009 DBD09, Waikoloa Hilton, Oct 12, 2009
K.Barry, E.Niner, A.Piepke Physics Dept, U. of Alabama, Tuscaloosa AL P.Vogel Physics Dept Caltech, Pasadena CA A.Bellerive, M.Bowcock, M.Dixit, K.Graham, C.Hargrove, E.Rollin, D.Sinclair, V.Strickland Carleton University, Ottawa, Canada C. Benitez-Medina, S.Cook, W.Fairbank Jr., K.Hall, B.Mong Colorado State U., Fort Collins CO M.Moe Physics Dept UC Irvine, Irvine CA D.Akimov, I.Alexandrov, A.Burenkov, M.Danilov, A.Dolgolenko, A,Karelin, A.Kovalenko, A.Kuchenkov, V.Stekhanov, O.Zeldovich ITEP Moscow, Russia B.Aharmim, K.Donato, J.Farine, D.Hallman, U.Wichoski Laurentian U., Canada H.Breuer, C.Hall, L.Kaufman, D.Leonard, S. Slutsky, Y-R. Yen U. of Maryland, College Park MD K.Kumar, A.Pocar U. of Massachusetts, Amherst M.Auger, G.Giroux, R.Gornea, F.Juget, G.Lutter, J-L.Vuilleumier, J-M.Vuilleumier Laboratory for High Energy Physics, Bern, Switzerland N.Ackerman, M.Breidenbach, R.Conley, W.Craddock, J.Hodgson, D.McKay, A.Odian, C.Prescott, P.Rowson, K.Skarpaas, J.Wodin, L.Yang, S.Zalog SLAC, Menlo Park CA P.Barbeau, L.Bartoszek, R.DeVoe, M.Dolinski, B.Flatt, G.Gratta, M.Green, F.LePort, M.Montero-Diez, R.Neilson, A.Reimer-Muller, A.Rivas, K.O’Sullivan, K.Twelker Physics Dept Stanford U., Stanford CA P.Fierlinger DBD09, Waikoloa Hilton, Oct09 TUM, Garching Germany Giorgio Gratta, EXO Overview 2
Xe is ideal for a large experiment is ideal for a large experiment Xe • No need to grow crystals No need to grow crystals • • Can be re Can be re- -purified during the experiment purified during the experiment • • No long lived No long lived Xe Xe isotopes to activate isotopes to activate • • Can be easily transferred in different detectors Can be easily transferred in different detectors • if alternate technologies become available if alternate technologies become available • Noble gas: Noble gas: easy(er easy(er) to purify ) to purify • • 136 Xe enrichment easier and safer: • 136 Xe enrichment easier and safer: - noble gas (no chemistry involved) noble gas (no chemistry involved) - - centrifuge feed rate in gram/s, all mass useful centrifuge feed rate in gram/s, all mass useful - - centrifuge efficiency centrifuge efficiency ~ m. For Xe Xe 4.7 4.7 amu amu - Δ m. For ~ Δ • 129 Xe is a hyperpolarizable hyperpolarizable nucleus, under study for NMR nucleus, under study for NMR • 129 Xe is a tomography… a joint enrichment program ? tomography… a joint enrichment program ? DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 3
Xe offers a qualitatively new tool against background: offers a qualitatively new tool against background: Xe ++ e - e - final state can be identified Xe 136 Ba ++ e - e - final state can be identified 136 Xe 136 Ba 136 using optical spectroscopy ( using optical spectroscopy (M.Moe M.Moe PRC44 (1991) 931) PRC44 (1991) 931) + system best studied Ba + system best studied Ba (Neuhauser Neuhauser, , Hohenstatt Hohenstatt, , ( 2 P P 1/2 2 Toshek, , Dehmelt Dehmelt 1980) 1980) Toshek 1/2 Very specific signature Very specific signature 650nm 650nm “shelving” “shelving” 493nm 493nm Single ions can be detected Single ions can be detected from a photon rate of 10 7 from a photon rate of 10 7 /s /s metastable 47s 47s metastable 4 4 D D 3/2 3/2 •Important additional Important additional • constraint constraint •Drastic background Drastic background • S 1/2 2 2 S 1/2 reduction reduction DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 4
• This may be the only viable technique if <m> This may be the only viable technique if <m> • happens to be very small happens to be very small • Xe Xe (in gas phase) (in gas phase) is is the best way to try using the best way to try using • decay kinematics to study the decay after decay kinematics to study the decay after it has been observed it has been observed Assume an “asymptotic” fiducial fiducial mass of mass of Assume an “asymptotic” 10 tons of 136 Xe at 80% 10 tons of 136 Xe at 80% Mainly going in Mainly going in A somewhat natural scale: A somewhat natural scale: light bulbs, light bulbs, • World production of World production of Xe Xe is ~40 ton/yr is ~40 ton/yr • plasma displays and plasma displays and satellite propulsion satellite propulsion • Detector size Detector size • 3 size increase: good match to the • 2 2• •10 10 3 size increase: good match to the • 2 eV 10 - eV mass region mass region 10 -2 DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 5
Klapdor et al. claim [0.17 – 0.45 eV] 100kg-class detectors ~100-200 meV sensit. EXO 1 ton, 5yr, 28 meV EXO 10 ton, 10yr, 6 meV Plot assumes Majorana neutrinos Plot from Avignone Avignone, Elliott, Engel arXiv:0708.1033 (2007) , Elliott, Engel arXiv:0708.1033 (2007) Plot from DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 6
The roadmap to the background-free discovery Done In progress To do of Majorana neutrinos and the neutrino mass scale LXe GXe Learn about Improve physics and the energy Gain practice economics Resolution Build a with Ba of Xe in LXe test chamber Gain practice trapping and enrichment (not low bkgnd) with Ba spectroscopy on a grabbing and in Xe and grand scale Design & release other gases build a Build a large size, Study energy test rig low and position Enrich a Build a fully functional for Background resolution for large ion grab, transfer, Ba-tagging prototype background amount trap, spectroscopy cell in HiPress LXe 0 νββ rejection of Xe gas detector (200 kg) Measure 2 νββ in Investigate 136 Xe, gain operational Enrich few direct tagging experience, reach the tons of Xe High press in LXe best 0 νββ sensitivity vessel engineering Design and build a large, ton scale experiment DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 7
EXO-200 See also: L.Yang, “Status of the EXO-200 experiment” DJ2, Thursday 19:15 R.Neilson, “Large Area APDs in the EXO-200 experiment” DJ3, Thursday 19:30 DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 8
Both ionization and scintillation readout to optimize E resolution � see Steve Elliott’s talk Expect σ E ‹1.4% at 2.5MeV 1 kV/cm ~570 keV keV ~570 E.Conti et al. , Phys Rev B 68 (2003) 054201 DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 9
EXO-200 TPC basics DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 10
Massive program of materials screening for radioactive contamination: D.S.Leonard et al ., NIM A 591 (2008) 490 (to be updated soon) DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 12
EXO-200 LXe TPC field cage & readout planes Central HV plane APD plane (copper) and (photo-etched acrylic supports grid plane (photo-etched phosphor bronze) phosphor bronze) ~40cm field shaping flex cables on back of APD plane rings (copper) teflon light reflectors DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 13
Massive use of bare, cold Large Area Avalanche Photodiodes � R.Neison et al. NIM A 608 (2009) 68
DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 19
EXO-200 Summary • TPC was tested with full electronics in the Summer First APD light 09 and passed all tests pulser data (but of course w/o LXe). • TPC being packed, to arrive WIPP on Oct 31, 09 • Commissioning test run of all cryogenics at WIPP ongoing • Expect to install TPC in the cryostat starting in ~ late Nov 09 • Expect to start running sometimes in early 2010 DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 20
Ba tagging R&D See also: A.Reimer-Mueller, “The Barium Tagging system for EXO” DJ4, Thursday 19:45 DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 21
Ba + identification in a Linear Ion Trap Linear Ion Trap Ba + identification in a U U CCD Ba oven Ba oven Spectroscopy Spectroscopy Scope Scope lasers lasers Vcos( Ω t) + U Vcos( Ω t) + U 0 Volts 0 Volts - gun e - gun e DC potential [V] DC potential [V] Ba Ba Buffer gas Buffer gas -5 Volts 5 Volts - DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 22
Electrode structure being prepared DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 23
First single ion detection in high pressure gas (He, Ar) ~9 σ discimination in 25s integration M.Green et al. arXiv:0702122, Phys Rev A 76 (2007) 023404 B.Flatt et al. arXiv:0704.1646, NIM A 578 (2007) 409 DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 24
Single ion spectroscopy & identification possible in some Xe atmosphere provided He is added to the trap p=10 -4 torr DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 25
Trap also allows for very “clean” ion transport + = “Static” unloading rate 0 . 81 2 . 87 mHz − 0 . 67 + = “Cycling” unloading rate 1 . 56 7 . 80 mHz − 2 . 34 DBD09, Waikoloa Hilton, Oct09 Giorgio Gratta, EXO Overview 26
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