Solid Xenon Detector R&D

Transcription

1 Solid Xenon Detector R&D Jonghee Yoo Fermilab 24 Feb 2012 UCLA Dark Matter Symposium

2 Solid Xenon Scintillation ~100 ev/γ Phonons ~100 mev/ph Ionization ~10 ev/el Why Xenon? No long-lived Xe radio isotope (no intrinsic background) High yield of scintillation light Scintillation wavelength : 175nm (optically transparent) Relatively high melting point : T m = 161K Simple crystal structure : fcc (same as Ge) Easy purification (distillation, etc) Self shielding : Z=54 Why Solid? For solar axion search, being a crystal is crucial (Bragg scattering) Even more scintillation light (61 γ/ kev) than LXe (42 γ/ kev) is reported Drifting electrons faster in the crystal Superb low noise superconducting sensors are running at low temperature (mk ~ K) Phonon read out : largest number of quanta (~10,000 phonons / kev) - In principle best energy resolution can be achieved in phonon channel - Luke-phonon readout will provide ionization energy and position information No further background contamination through circulation loop (no convection mix) Optimal detector design for low background experiment - Possible container-free design - No outgassing issue 2

3 Science (1) Solar axion search: crystal - scin5lla5on / (ioniza5on) (2) Dark ma<er search : readout two(or three) signals - scin5lla5on / ioniza5on / (phonon) (3) Neutrinoless double beta decay (0v2b) : 136 Xe enriched - scin5lla5on / ioniza5on / phonon (4) pp- Solar neutrino measurement : 136 Xe depleted (5) Supernova detec5on (6) Neutrino coherent sca<ering (7) Medical usage (MRI/NMR) : hyperpolarized 131 Xe Time-energy plot of the expected event rate for finding photon-converted solar axions with a CDMS germanium crystal detector Full of science topics Strong mo5va5on for R&D But this does not necessarily mean we can ini5ate science experiment. We need proven technology in order to achieve immediate science goal Low background crystal detector 3

4 Solid Xenon Property? ΔT = 4K Compact More electrons / kev? or less?? Faster electron dri\? Slow hole(?) dri\ Single direc5onal Luke- phonon? Not many proper5es are known nor measured in solid phase 4

5 Xenon Crystal? Kramer 1976 : Epitaxial growth of xenon crystal on Carbon- graphite film 5

6 Previous Efforts Fukui Univ. (Miyajima 1999) TAMU (J.White 2004) Measured ioniza.on signal from Solid Argon 6

7 Solid Xenon R&D Phase-1: Frozen Xenon Frozen xenon Frost xenon layers 7

8 Solid Xenon R&D Phase-1 (2010) Liquid Xenon (~200g) Fermilab Center for Par5cle Astrophysics (FCPA) New Ini5a5ve R&D Project Phase- 1 Goal: demonstrated ~1kg size of op.cally transparent solid phase of xenon Collabora5on with T. Saab, D. Balakishiyeva (U.Florida) R.Mahapatra (TAMU) Solid Xenon (~850g) Established Recipe Top T : 160 ± 0.5K BoJom T : 145 ± 0.5K Xenon gas pressure : 1.0 ± 0.1 atm Pa.ence : 3cm growth / 10 hours Phase- 2 Fermilab Par5cle Physics Division (PPD) review panel approved Phase- 2 (April 2010) (1) Automate process (2) Signal readout (scin5lla5on and ioniza5on) Budgetary approval (June 2010) 8

9 Solid Xenon R&D Phase-2 Electric feedthroughs New design of inner glass (xenon) chamber and electric/gas feed throughs Address safety concerns of using glass chamber system Engineering support from Fermilab PPD 4 D glass chamber 9 D glass chamber PMT or TPC Cryobath phase separator Glass chamber pressure simula.on (H.Cease) Max. allowed pressure < 17.5 psig 9

10 New Plumbing 10

11 Automatic control system Touch screen control unit Cryobath level, temperature, pressure and flow rates control Monitoring (graph) tools, remote control (D.Markley) Programmable Logic Controller 11

12 Gas purification/analysis system Noble Gas Purifier (U.Florida) RGA Universal Gas Analyzer 12

13 Photomultiplier Hamamatsu R9869 Spectral Response 169 ~ 650 nm Operating ambient temperature : 163K ~ 323K Quantum Efficiency at 175nm : 20% Gain : 10 6 Anode pulse rise time : 2.3 nsec Weight : 95g Pressure resistance : 5 atm data/ntp/ _pmtv0860ledmv09745_t160k020mhz.root Entry " / ndf / 27 a ± 62.9 µ e+05 ± 4.863e # e+05 ± 3.759e+03 a ± 3.62 µ e+06 ± 1.302e+05 # e+06 ± 1.174e Single p.e. calibration in cold temperature G = 4.2e6 (@860V, 160K) or 33.6pVs at s.p.e Gain 6!10 V.Anjur (IMSA) 13

14 TPC TPC performance test done in gas Argon Δt=at0- ct0 anode t0 (at0) cathode t0 (ct0) 7cm 2cm Anode (+500V) Anode Grid Field shape rings Ground Grid Cathode(- 215V) Photocathod: Gold- coated on Al plate Au Custom Al, PLATYPUS FC MΩ Resistance (W.Jaskierny and E.Skup) TPC design is from LArTPC project at Fermilab 14

15 Solid Xenon Phase-2 Test Stand Safety backup chambers Xenon gas storages and Calibra5on gas storage Gas control DAQ Main chamber System setup completed in 2011 Sep Passed Fermilab safety review Electric safety review 2011 Nov Mechanical safety review 2011 Nov Cryogenic safety review 2012 Dec Opera.onal Readiness Clearness 2012 Nov Approval for system opera5on 2011 Dec System test 2012 Jan ~ Feb 15

16 System Test gas liquid solid 16

17 System test: Scintillation Light (last week) PMT pulses (sequen.al segment readout) Solid Xenon (cosmic ray test) Ini.al test of scin.lla.on light readout Research grade xenon (<ppm for H 2 O, O 2, N 2, ) Radioac.ve source test to be done Amer full system test (coming soon) (1) Measure scin.lla.on efficiencies (2) Measure electron drim (3) Compare proper.es in liquid vs. solid (4) Measure other interes.ng detector parameters 17

18 Summary Solid Xenon Phase- 2 instrument is ready for the opera.on System test is underway - Seeing scin.lla.on light from solid xenon - Detailed system test to be done More to come! 18