Transcript Slide 1

SIGN
(Scintillation and Ionization in Gaseous Neon)
A High-Pressure, RoomTemperature, Gaseous-Neon-Based
Underground Physics Detector
J.T. White
Texas A&M University
Institutions:
TAMU, UCLA
Henderson-DUSEL-Capstone
Workshop
May, 5 2006
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
100 atm NeXe
PMT
Electrofluorescence
Mostly 175 nm
PMT
Sapphire
+HV
- HV
Cell
Argon Flow
Charge Amp
Radioactive
source
55Fe
Signal in Ne/Xe(0.5%)
Primary
Light
~2 us
Photoelectric from SS
QE ~ .02% @175 nm ?
Secondary
Charge
charge preamp signal
- note kink
55Fe
6 keV
6 keV gamma
in Ne-Xe(0.5%)
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%)
Gamma Event
Primary
(S1)
HV – ON!
Secondary
(S2)
Neutron Event
Areas Same
i.e. ionization same
Nuclear Recoil Discrimination: S2 vs S1
AmBe Neutron Source
100 atms Ne/Xe(0.5%)
Zoomed View
RedCs-137 + 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
ZERO Field
Gammas(?)
Neutrons
4-PMT Cell: Pure Neon
ZERO Field
Gammas(?)
Neutrons
WIMP
Physics ?
WIMP
σ/atom  A2
R/kg  A
Er
WIMP – Dark Matter
Visible Energy?
Inelastic
Efficiency
Lindhard
Lindhard
Lindhard * Threshold Effect
Recoil Energy
Visible Energy (e.e.)
Potential WIMP Sensitivity?
ASSUMING:
1)Threshold ~ 1 keVee
1 ton 2)Good Discrimination
 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
SIGN concept
WIMP
Cylinder
• Neon Gas
– P >= 100 atm
– + Xenon 0.1-0.5 % ?
• CsI Photocathode
• Sense & Field wires
• WLS fibers
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
SIGN Conceptual Design
MgF2- coated
LEXAN light guide
PMT
Both Ends
WLS Fibers
Coated With TPB
Charge Readout
-Both Ends
-Can sum wires
Size? 100 bar, 2m Water Shield
10 tons
5m
9m
1 ton @ 100 bars
9m
5m
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