1. 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 SNOLAB workshop V Aug, 22 2006 Institutions: TAMU, UCLA

2. High Pressure Gaseous Neon? High Pressure Gaseous Neon?  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 !

3. WIMP – Recoil Spectrum Complimentary to Xe, Ge, Ar Slope strongly dependent on WIMP mass & velocity dispersion(?)

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

5. Potential WIMP Sensitivity? 1 ton  Few 10 -46 cm 2 ? IF Threshold ~ 1 keV

6. 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 10 -44 N 2 (E/1 MeV) 2 cm 2 = Er_MAX/3 keV Drukier, Stodolsky, PRD 30 (11) (1984) 2295-2309 Cabrera, Krauss, Wilczek, PRL 55(1) (1985)25-28

7. Neutrinos –Supernova? E ~ 3 x 10 53 ergs ν e ~ 3.0 x 10 57 ν ebar ~ 2.1 x 10 57 ν x ~ 5.2 x 10 57 ~ 10 kpc Earth # neutrinos: sum Horowitz, Coakley, McKinsey, PRD 68 023005 (2003)

8. Neon Coherent Elastic Scattering neutrino A = 20 Z=10 N=10 σ ~ 0.42 x 10 -44 N 2 (E/1 MeV) 2 cm 2 ~2.5 evts/ton Flavor Indep!

9. SIGNAL in HP-Ne? 100 atm Test Cell PMT Radioactive source +HV - HV Sapphire 100 atm NeXe Electrofluorescence Mostly 175 nm PMT Cell Argon Flow Charge Amp

10. 55 Fe Signal in Ne/Xe(0.5%) Primary Secondary Photoelectric from SS QE ~.02% @175 nm ? charge preamp signal - note kink S2 Light Charge ~2 us

11. 55 Fe 6 keV gamma in Ne-Xe(0.5%) Light Charge 6 keV

12. Another Example:  Excellent Resolution ! 241 Am gammas 60 keV Charge Signal

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

14. Field Tuning Field Tuning Adjust field tube potential to optimize E-field uniformity along sense wire

15. Sapphire Windows TPB coating

16. Event Waveforms Neutron Event Gamma Event Areas Same i.e. ionization same Secondary (S2) Primary (S1)

17. S2 pulse width Low energy gammas and neutrons Multiple scatters, photoelectric x-rays & higher energy gammas Width increase vs drift time  Can determine diffusion coeff.

18. Nuclear Recoil Discrimination: S2 vs S1 AmBe Neutron Source 100 atm Ne/Xe(0.5%) zoom in

19. Nuclear Recoil Discrimination: S2 vs S1 Drift regions Higher field  S2/S1 field (and density) dependent for nuclear recoils  Gammas unaffected (Emin ~ 600 v/cm here) Lower field

20. S2/S1 Discrimination Gammas Neutrons vs S2vs S1 S2 / S1

21. Primary Pulse Shape Discrimination

22. S2/S1 AND Primary Shape Discrimination! Primary Pulse Shape Discrimination Gammas Neutrons

23. S2/S1 AND Primary Shape Discrimination! Primary Pulse Shape Discrimination Gammas Neutrons

24. Gas Mixture Studies ZERO Field Neutrons Gammas Point sampling: pure Ne  Ne-Xe  Ne-Ar  Ne-He mixures all show discrimination. L/Q output, primary decay times vary with mixtures. Need full study.

25. SIGN conceptual design Neon + ? Gas Neon + ? Gas CsI Photocathode CsI Photocathode Sense & Field wires Sense & Field wires WLS fibers WLS fibers e.g. Diameter ~ 50 cm Length ~ 5 m Mass >~ 100kg @ 100 atm WIMP Primary Ionization Prompt Scintillation Photoelectrons Cylinder

26. 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

27. Off-the-shelf Module ~ 3 m ~ 40 cm spun aluminum carbon fiber winding 43 cm diameter 300 cm length 6000 psi = 408 atm

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

29. Detector Layout 1 ton @ 100 bars 10 tons 5 m 9 m 2- 4 m water/acrylic shields

30. Possible 100 Ton Detector

31. WIMP sensitivity - Oscillation Future: WIMP velocity dispersion measurement

32. Nuclear Recoil Calibration and Signal Efficiency Determination: Li(p,n)Be reaction  ~ monochromatic neutrons with Energies up to ~ 2 MeV  Beam commissioning in progress TAMU Proton Accelerator – 4 MeV max

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