The Search for Dark MatterStatus, Zeplin II, SIGN, Future
orNature, RED in Tooth and Fang
James T. WhiteHEP Lunch
2-15-06
Dark Matter Distribution?
Dark Matter Experiments• US
– CDMS - ultra-cold Ge– ZEPLIN - two-phase LXe– XENON - two-phase LXe– CLEAN - LNe (+ LAr)– SIGN - Gaseous High Pressure Neon
• EU– DAMA - NaI– CRREST + EDELWEISS - Ge + Sapphire?– WARP - LAr– ArDM - LAr
• Others…. Genius, Drift, XMAS, EURICA … ?
ZEPLIN IIZoned Electro-luminescence and Primary
Light In Noble-gasesDB Cline, M Atac, Y Chen, Y Seo, F Sergiampietri(a), H Wang Physics and Astronomy, UCLA , (a) Pisa
GJ Alner, C Bungau, B Camanzi, JD Lewin, RM Preece, NJT Smith, PF SmithParticle Physics Department, Rutherford Appleton Laboratory, Chilton, Oxon
B Ahmed, A Bewick, D Davidge, JV Dawson, AS Howard, I Ivaniouchenkov, WG Jones, MK Joshi, V Lebedenko, I Liubarsky, R Lüscher, T J Sumner, J J QuenbyBlackett Laboratory, Imperial College of Science, Technology and Medicine, London
MJ Carson, E Daw, T Gamble, VA Kudryavtsev, TB Lawson, MJ Lehner, PK Lightfoot, JE McMillan, B Morgan, SM Pealing, M Robinson, NJC Spooner, DR ToveyDepartment of Physics and Astronomy, University of Sheffield
P PicchiICGF-CNR-Torino
JT White, J GaoDepartment of Physics, Texas A&M University
ZEPLIN II: Two-Phase XenonWIMP
5 inch VUV PMTsOperate to LN2 tempLow bkg materials
Drift Field
Electroluminescence FieldExtraction Field(~5 kV/cm for 100%)
Primary scintillation
Ionization
Secondary Scintillation
PTFE Reflector
Xenon
Signal
Primary Secondary
ZII - DAQDual OutX10 AMP
∑ out
DiscriminatorsPMTs
TriggerN out of 7
Acqiris DC265500 MHz Digitizer2 Mbyte/channel
PC
TAMU
ZII – Gas Test
Direct Detection:Expected Signal
Gammabackground
electronrecoil
Target Nuclei
nuclear recoil
WIMP orNeutron
Scintillation
Ionization
Background Discrimination
ZII - Assembly
UCLA - WANG
ZII: Internals
TAMU
ZII - InternalsTAMU
ZII - InternalsTAMU
ZII – Assembly
TAMU
ZII - Assembly
ZII - Assembly
ZII - Assembly
ZII – Gas Test
ZII ProgressSurface LXe Tests at RAL
Ba -133 Cs-137 Co-60
Cs-137 AmBe
356 keV~400 pe
356 keV~700 pe 1250 keV
~1250 pe
Two-Phase
Nuclear recoils
Zero-Field
ZIIGRID UPGRADE - TAMU
88% transparency Cold deflection test
HV UPGRADE
UCLA
TAMU
Target Integrationshowing wire mesh, field shaping rings,
the PTFE structure to confine liquid xenonand gas extraction
device
Installation of improved HV feedthrough, HV internal Cable
ZII Commissioning
S2/S1
Drift Time (ns)
S2 (p.e.)
Drift Time (us)
Alphas from Radon chain
Fit to slope gives electron lifetime
lifetime ~ 8 us and improving
Recirculating Purifier - UCLA
Commissioning
Today ! Charge Collection > 98%
Feb 14, 2006
600 ms
ZII TAMU Recoil Calibration
Zero-Field
60 keV
>300 pe
Two-Phase
S1
S2
ZII SUMMARY
All is working (Perfectly?)
Electron Lifetime > 100 ms(> 10 X drift time)
Physics Run Starting !
TAMU Calibration soon !
SIGN(Scintillation and Ionization in Gaseous Neon)
A Dark Matter/Neutrino Detector based on
Gaseous Neon
Institutions:TAMU, UCLA
FIRST !
Ans: Electron mobility !
Possibility for Primary vs Secondary Nuclear Recoil Discrimination
Why Gaseous Neon?
Nuclear recoil for neutrinos >~ 10 MeV
WIMP – Dark MatterWIMP
Ne
NuclearRecoil
F(Q2) ~ 1
Kinematics AND
Form Factor
Er
WIMP
Potential WIMP Sensitivity?
1 ton
Few 10-46 cm2 ?
ASSUMING:1)Threshold ~ 1 keVee2)Good Discrimination
Neutrino Applications? -Supernova
E ~ 3 x 1053 ergs
νe ~ 3.0 x 1057
νebar ~ 2.1 x 1057
νx ~ 5.2 x 1057
~ 10 kpc Earth
# neutrinos:sum
Horowitz, Coakley, McKinsey,PRD 68 023005 (2003)
Neon Elastic Scattering
Z0
neutrino
neon nucleus
A = 20Z=10N=10
σ ~ 0.42 x 10-44 N2 (E/1 MeV)2 cm2
Neon Response
Observed Spectrum
Events per ton
10 ton detector ~25 NR evts @ 10 kpc
Solar Neutrinos
Er_MAX = (2/A) (Eν2/1 MeV)2 keV ~ 10 keV for Ev = 10 MeV
8Be: Flux ~106/cm2/s E > 10 MeV
Coherent Nuclear Scattering:
~ 15 evts/year/ton Er: 3 10 KeV
σ ~ 0.42 x 10-44 N2 (E/1 MeV)2 cm2
<Er> = Er_MAX/3 keV
Drukier, Stodolsky, PRD 30 (11) (1984)2295-2309
Cabrera, Krauss, Wilczek, PRL 55(1)(1985)25-28
SIGNAL? Threshold?100 Bar Test Cell
Test Cell
PMT
Radioactivesource
+HV- HV
Sapphire
100 atm NeXe ElectrofluorescenceMostly 175 nmPMT
Cell
Argon Flow Charge Amp
55Fe Signal
Primary
Secondary
Photoelectric from SSQE ~ .02% @175 nm
charge preamp signal- note kink
Light
Charge
~2 us
55Fe SpectraLight
Charge
1 KeV Threshold Feasible !
Nuclear Recoil Discrimination?4-PMT 100 bar Test Cell
4-PMT Test Cell
PTFE reflector
Field tube
4-PMT Test Cell SignalsNeutron EventGamma Event
Areas Samei.e. ionization same
Secondary(S2)
Primary(S1)
Nuclear Recoil Discrimination: S2 vs S1
AmBe Neutron Source
100 bars Ne/Xe(0.5%)
Zoomed View
Red-Cs-137 + Co-60 run
Gammas
Neutrons
S2/S1 vs S1
Primary Shape?
S2/S1 AND Primary ShapeDiscrimination!
Primary Pulse Shape Discrimination
Gammas
Neutrons
Rejection Power? – not yet estimated
SIGN concept
• Neon Gas – P >= 100 atm– + Xenon 0.1-0.5 % ?
• CsI Photocathode• Sense & Field wires• WLS fibers
e.g.Diameter ~ 50 cmLength ~ 5 mMass >~ 100kg @ 100 atm
WIMP
Primary IonizationPrompt Scintillation
Photoelectrons
Cylinder
Pressure Vessels?•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
PMTBoth Ends
Charge Readout-Both Ends-Can sum wires
MgF2- coatedLEXAN light guide
WLS FibersCoated With TPB
Structure of Inner Cylinder
Blue-Green WLS Fiber
TPBVUV toblue
Sense wire
Stainless Steel Inner CylinderHollow, Stiff
Field/Gating Wires
Infrastructure Requirements100 bar with 2m Water Shield
1 ton @ 100 bars
10 tons
~ 9 x 9 x 9 m
Gas Storage ~ 5X4X4 mElectronics ~ 3X3X3 m
Need to discuss with engineers
SIGN Summary• Room-Temperature, High-Pressure, Gaseous
Neon appears to have excellent potential as a dark matter (and 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
mass?
Possible 100 kg Detector
SIGN – Radio Assay?
Drift time
Charge
Alphas
Auger electrons35-55 keV
Nuclear recoils?Neptunium 237?
Am-241 source in situ
ZEPLIN II/III
FUTURE ?
Active Xe
Xe Self shield
Vacuum
HV
CsI Coated
CsI internal photo-cathode –4-pi light collection (except shadow)6 photo-electron/keV1.6 ton fiducial, 5.8 ton total28 cm xenon self shieldStructurally soundMinimized field shaping structure (Less materials)Extremely low backgroundMeasure both scintillation and ionization (3-D events mapping)background rejectionCompact design
CablingUCLA - TAMU
Reverse operation of a cold-emissionDevice to achieve charge gain in
liquid near the tip
Future – PMT-Less LXe
UNCD-coated
M. Hajra, JOURNAL OF APPLIED PHYSICSVOLUME 94, NUMBER 6
Si Uncoated
Extremely sharpand uniformly distributed micro-
tips can be manufactured in
large scale
SUMMARY
• ZEPLIN II – run begins now – reach? 10-8 pb/nucleon?
• SIGN – TAMU Innovation – will certainly exist in the future if only to measure WIMP mass and Halo velocity distribution
• TAMU-UCLA – PMT-Less Detectors –preparing proposals now
• The future of DM Research is Bright!
