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 Henderson-DUSEL-Capstone Workshop May, Institutions: TAMU, UCLA

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

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

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

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

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

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

Sapphire Windows TPB coating

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

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

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

Primary Pulse Shape?

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

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

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

WIMP Physics ? WIMP Er σ/atom  A 2 R/kg  A

WIMP – Dark Matter

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

Potential WIMP Sensitivity? 1 ton  Few cm 2 ? ASSUMING: 1)Threshold ~ 1 keV ee 2)Good Discrimination

Solar Neutrinos? Er_MAX = (2/A) (E ν 2 /1 MeV) 2 keV ~ 10 keV for Ev = 10 MeV 8 Be: Flux ~10 6 /cm 2 /s E > 10 MeV Coherent Nuclear Scattering:  ~ ~ 15 evts/year/ton Er: 3  10 KeV σ ~ 0.42 x N 2 (E/1 MeV) 2 cm 2 = Er_MAX/3 keV Drukier, Stodolsky, PRD 30 (11) (1984) Cabrera, Krauss, Wilczek, PRL 55(1) (1985)25-28

Neutrinos –Supernova? E ~ 3 x ergs ν e ~ 3.0 x ν ebar ~ 2.1 x ν x ~ 5.2 x ~ 10 kpc Earth # neutrinos: sum Horowitz, Coakley, McKinsey, PRD (2003)

Neon Coherent Elastic Scattering Z0Z0 neutrino neon nucleus A = 20 Z=10 N=10 σ ~ 0.42 x N 2 (E/1 MeV) 2 cm 2

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

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

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

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

Size? 100 bar, 2m Water Shield bars 10 tons 5 m 9 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, 8 B, 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