J.T. White Texas A&M University

SIGN (Scintillation and Ionization in Gaseous Neon) A High-Pressure, Room-Temperature, Gaseous-Neon-Based Underground Physics Detector J.T. White Texas A&M University Henderson-DUSEL-Capstone Workshop May, 5 2006 Institutions: TAMU, UCLA

First ! 1) Why Gaseous Neon? Electron mobility ! Possibility for Primary vs Secondary Nuclear Recoil Discrimination 2) What Pressure? ~100  300 atms !  ~ 8  25% liquid density 3) What Temperature?  Room T !

SIGNAL? 100 atm Test Cell – Ne/Xe Test Cell Electrofluorescence Mostly 175 nm 100 atm NeXe PMT PMT Sapphire +HV - HV Cell Radioactive source Charge Amp Argon Flow

55Fe Signal in Ne/Xe(0.5%) Primary ~2 us Light Photoelectric from SS QE ~ .02% @175 nm ? Secondary Charge charge preamp signal - note kink

55Fe 6 keV gammain Ne-Xe(0.5%) 6 keV Light Charge 1 KeV Threshold Feasible ?

Another Example: 100 atm Ne-Xe(0.5%) 241Am 60 keV Charge Signal

Nuclear Recoil Discrimination?4-PMT 100 atm Test Cell 4-PMT Test Cell Field tube PTFE reflector

Sapphire Windows TPB coating

4-PMT Test Cell:Ne-Xe(0.5%) HV – ON! Neutron Event Gamma Event Areas Same i.e. ionization same Primary (S1) Secondary (S2)

Nuclear Recoil Discrimination: S2 vs S1 AmBe Neutron Source 100 atms Ne/Xe(0.5%)

Zoomed View Red- Cs-137 + Co-60 run S2/S1 vs S1 Gammas Neutrons

Primary PulseShape?

S2/S1 AND Primary ShapeDiscrimination! Primary Pulse Shape Discrimination Gammas Neutrons Rejection Power? – not yet estimated

4-PMT Test Cell: Pure Neon ZERO Field Gammas(?) Neutrons

4-PMT Cell:Pure Neon ZERO Field Gammas(?) Neutrons

WIMP σ/atom A2 R/kg  A WIMP Physics ? Er

WIMP – Dark Matter

Visible Energy? Inelastic Efficiency Lindhard Lindhard Lindhard * Threshold Effect Visible Energy (e.e.) Recoil Energy

Potential WIMP Sensitivity? • ASSUMING: • Threshold ~ 1 keVee • Good Discrimination 1 ton  Few 10-46 cm2 ?

Solar Neutrinos? 8Be: Flux ~106/cm2/s E > 10 MeV Coherent Nuclear Scattering: Drukier, Stodolsky, PRD 30 (11) (1984) 2295-2309 Cabrera, Krauss, Wilczek, PRL 55(1) (1985)25-28 σ ~ 0.42 x 10-44 N2 (E/1 MeV)2 cm2 Er_MAX = (2/A) (Eν2/1 MeV)2 keV ~ 10 keV for Ev = 10 MeV <Er> = Er_MAX/3 keV  ~ ~ 15 evts/year/ton Er: 3  10 KeV

Neutrinos –Supernova? Earth ~ 10 kpc E ~ 3 x 1053 ergs # neutrinos: sum νe ~ 3.0 x 1057 νebar ~ 2.1 x 1057 νx ~ 5.2 x 1057 Horowitz, Coakley, McKinsey, PRD 68 023005 (2003)

Nuclear Recoil Yield? ~2.5 Events per ton Per 10 kpc 10 ton detector  ~25 NR evts @ 10 kpc

Neon Gas P >= 100 atm + Xenon 0.1-0.5 % ? CsI Photocathode Sense & Field wires WLS fibers SIGN concept WIMP Cylinder e.g. Diameter ~ 50 cm Length ~ 5 m Mass >~ 100kg @ 100 atm Primary Ionization Prompt Scintillation Photoelectrons

Pressure Vessel? • Composite cylinders • Carbon, Kevlar wound • Some rated > 10000 psi ! • Used on mass transit (Methane)) • Used for Hydrogen fuel cells • On jets, spacecraft • DOT certified ! • Perhaps cast in acrylic blocks

SIGNConceptual Design MgF2- coated LEXAN light guide WLS Fibers Coated With TPB PMT Both Ends Charge Readout -Both Ends -Can sum wires

Size? 100 bar, 2m Water Shield 10 tons 5 m 9 m 1 ton @ 100 bars 9 m 5 m

Summary-A • Room-Temperature, High-Pressure, Gaseous Neon (or Ne+X) is proposed as a dark matter/ neutrino Target • It is radio-quiet! • Shows excellent (potential) NR Discrimination in BOTH S2/S1 and Primary Pulse Shape ! • ~ $80k/ton • Will be important in the future to help pin down WIMP mass & velocity distribution? • May be able to detect SN, 8B, Geo-Fission(?) neutrinos – flavor independent?

Summary - B • At this point in R&D Phase • Need space underground to test CsI gating (Depth not critical for this) • With funding can start ~summer 2007 • Space for 1 ton ~ 10m X 10m water shielded room + counting house and gas storage • Depth for physics ~ >4000 mwe? • Will need more people

J.T. White Texas A&M University