Download - UKDM Programme
July 2001 Neil Spooner
UKDM ProgrammeUKDM ProgrammeUpdate on NaI, ZEPLIN and DRIFTUpdate on NaI, ZEPLIN and DRIFT
Neil Spooner, University of Sheffield
July 2001 Neil Spooner
New Caverns
More lab space than Soudan
50 m
£3.1M Award to University of Sheffield - Joint Infrastructure Fund grant
Collaboration with RAL
Surface facilities
Workshop, offices, etc.
Underground facilities
New much larger clean area
Upgrade of existing areas
New U/G Infrastructure 2000New U/G Infrastructure 2000
July 2001 Neil Spooner
50m
Stub 2
Stub 2a,3
‘H’ Area
JIF Area
Boulby U/G FacilitiesBoulby U/G Facilities
July 2001 Neil Spooner
~1500m2 new lab space
Experimental Halls
Clean Bay
Control Room
WorkshopDRIFT
Bay
Store
Workshop
Mess
Coms/Elecs.
Changing
Control RoomClean
Clean Bay
Runningboards
6m
20m
47m 14m
8m
8m
20m
Transfer Transfer
3.8mLaboratoriesClean roomsWorkshopMessFibre optic/Enet
New JIF Underground FacilityNew JIF Underground Facility
July 2001 Neil Spooner
~ 1500 m2 new space
New Area Under ConstructionNew Area Under Construction
July 2001 Neil Spooner
Main experimental hall will have 4-5m FLAT room
DRIFT 1 site
DRIFT Area ConstructionDRIFT Area Construction
July 2001 Neil Spooner
New Surface LaboratoryNew Surface Laboratory
July 2001 Neil Spooner
Contact me: Neil Spooner - [email protected]
Facility Management Board International Boulby Research Board
Facility manager and staff Projects co-ordinator
Institute for Underground Science
Plenty of new lab space available
Call For ProposalsCall For Proposals
July 2001 Neil Spooner
NaIsmall array
20 kg
NAIADhigh rate array
50 kg
UK-Saclay20 kg
NAIAD array
existing
ramp down
ZEPLIN-Isingle phase
PSD4 kg
ZEPLIN-IIion-scint
two phase Xe30 kg
ZEPLIN-IIIIon-scint
two phase Xehigh field
6 kg
ZEPLIN array
under construction
existing ZEPLIN-MAXion-scint
two phase Xe1000 kg
MULTINATIONAL
concept
under construction
DRIFT 1directional
1 m3
DRIFT array
DRIFT 10directional
10 m3
MULTINATIONAL
concept
2000 2002 2003 2004+2001
Boulby Dark Matter ProjectsBoulby Dark Matter Projects
July 2001 Neil Spooner
QMW: J. C. Barton University of Surrey: E. Morton, P. Sellin
CERN/Padova: A Pietropaulo ITEP: D Akimov, V Lebedenko, A Danilov
Coimbra: A Policarpo, M Salete Leite, R Ferreira Marques, V Chepel
UCLA: D Cline, M Atac, H Wang, J K Woo, J Park Columbia: C Hailey, J Hong, E Aprile, A Castellina
UCSD: K Griest, G Masek, K BucklandTemple University: C J Martoff, P Ambrozewicz, E Kaczanowicz
University of Sheffield: T. Gamble, V. A. Kudryavtsev, T. B. Lawson, M. Carson, S. Paling, P. K. Lightfoot, J. E. McMillan, B. Morgan, M. Robinson, N. J. C. Spooner, L. Thompson, D. R. Tovey, G. Nicklin
Rutherford Appleton Laboratory: G. J. Alner, E.G. Capocci, S. P. Hart, J. D. Lewin, R. Lüscher, R. M. Preece, J. W. Roberts, N. J. T. Smith, P.F. Smith
Imperial College of Science, Technology and Medicine: B. Ahmed, A. Bewick, D. Davidge, J. V. Dawson, A. S. Howard, I. Ivaniouchenkov, W. G. Jones, M. K. Joshi, V. Lebedenko, I. Liubarsky, T. J. Sumner, J. J. Quenby
Torino: P Picchi, L Periale, G Mannocchi, C Taricco, C Castagnoli, A CurioniSaclay: G. Gerbier
Occidental College: D Snowden-Ifft, T Ohnuki, N Villaume, J Burwell LLNL: B Craig, M J Lehner
UKDMC Boulby Dark Matter Collaboration (BDMC)
People Involved in Dark MatterPeople Involved in Dark Matter
July 2001 Neil Spooner
Boulby NAIAD ProgrammeBoulby NAIAD Programmestatus and programme
• Low-A target (Na) for WIMP masses < 200 GeV/c2 to reach 0.1/kg/d
MotivationMotivation
• Pulse shape discrimination and known technology that can be scaled up
--> Complements liquid Xe high-A
--> satisfies requirement for (i) recoil identification and (ii) diagnostic array capability
• Information relevant to DAMA using the same target, NaI
July 2001 Neil Spooner
UKDMC NaI - PSAUKDMC NaI - PSA
low activity silica
light guides & PMT shield
double zone refined NaI(Tl) crystalPMT
Example time constant distributions for new crystal DM72
showing log gauss neutron and compton fits and data.
E - 12-15 keV
neutron
Compton1996 limit from DM46 spin-independent
Schematic of early NaI detector e.g. DM46
NaI(Tl) Integrated Pulse-Shape
July 2001 Neil Spooner
• Following improvement to DM46 (5 kg) - discovery of fast events in NaI
Data (E 35-40 keV)
calibration
Example histogram for DM46 showing anomalous events
Typical fast event energy distributions in various crystals of different geometry
NaI Anomalous Events (1998)NaI Anomalous Events (1998)
Anomaly
July 2001 Neil Spooner
UKDMC NaI + SaclayUKDMC NaI + Saclay• Collaboration with Saclay to run a “DAMA” crystal at Boulby
• very similar spectrum of fast events seen again
RESULT
• this despite very different manufacture and geometry
UKDMC spectrum
anomalous event spectra in NaI
Saclay (“DAMA”) spectrum
July 2001 Neil Spooner
DAMA PSDDAMA PSDDAMA PSDDAMA PSD
UKDMC anomalous event spectra
Limit on anomalous events from DAMA old PSD data
July 2001 Neil Spooner
• Many underground and laboratory tests performed
lead/copper shieldingwater
shielding
paraffin light guide
silica light guides
• not internal activity• too fast for neutrons
RESULT
• not external betas….
• most likely surface implanted outgoing alphas
(a)
Example distribution for DM26 exposed to external low E alphas
alphas gammas
E 30-40 keV
NaI Anomalous Events (1998)NaI Anomalous Events (1998)
Anomaly seen in many crystals: Different manufacture, Different aspect ratio, Different history
July 2001 Neil Spooner
Outgoing Surface Alphas?Outgoing Surface Alphas?
• Outgoing events
– Radon implantation?
– Surface contamination?
• Supported by recent surface treatment results
• 222Rn → 218Po + α; • 218Po → 214Pb + α; • 214Pb → 214Bi + β + ν (+ γ); • 214Bi → 214Po + β + ν (+ γ); • 214Po → 210Pb + α; • 210Pb → 210Bi + β + ν (+ γ); • 210Bi → 210Po + β + ν (+ γ); • 210Po → 206Pb + α;
0.0001
0.001
0.01
0.1
1
1 10 100 1000
E keV
10-4
10-3
10-2
10-1
100
10.0 100.0 1000.0 10000.0
Energy (keV)
~0.005ppb U
July 2001 Neil Spooner
Identification of the eventsIdentification of the events
• Confirmed with CsI - easier to use unencapsulated than NaI
anomalous events
CsI Test (DM71)
known internal alphas
after surface polish
prior to surface polishCsI
July 2001 Neil Spooner
UKDMC spectrum
Saclay (“DAMA”) spectrum
DM74 limit onfast event spectrum
UKDMC spectrum
Saclay (“DAMA”) spectrum
DM74 limit onfast event spectrum
anomalous event spectra in NaI
• anomalous events reduced in NaIRESULT
• BUT at least 3-4 months exposure to Rn would be needed! - difficult to explain
• Confirmed with unencapsulated NaI (DM74)
distribution for pre-polished unencapsulated crystal DM74 after 5 mns operation
no fast eventswithin stat
Identification of the eventsIdentification of the events
Are the fast events in any way related to the DAMA result?
July 2001 Neil Spooner
NAIAD DesignNAIAD Design
dry nitrogen or mineral oil
• Unencapsulated units for 5-10 kg NaI crystals built
OFHC boxOFHC boxPTFE PTFE
crystal crystal cagecagecrystal
July 2001 Neil Spooner
NAIAD Programme - H-AreaNAIAD Programme - H-Area• 35 kg Unencapsulated surface controlled NaI
• 15 kg Encapsulated high light yield NaI
• 10 kg Saclay crystal
NaI unencapsulatedcraneglove
box
to JIF area
H area map
H 1
H 2
Controlroom
July 2001 Neil Spooner
NAIAD InstallationNAIAD Installation
July 2001 Neil Spooner
NAIAD Preliminary ResultsNAIAD Preliminary Results
July 2001 Neil Spooner
Boulby Xenon ProgrammeBoulby Xenon Programme
Xe*
+Xe
Xe2*
Triplet27ns
Singlet3ns
2Xe2Xe
175nm175nm
Excitation
(recombination)
Xe** + Xe
Xe2+
+e-
Xe+
+XeIonisation
Nuclear/Electron Recoil
three discrimination three discrimination techniquestechniques
(1) scintillation pulse shape
(2) ionisation-scintillation
- low field-
(3) ionisation-scintillation
- high field, low threshold -
single phase Xe two phase Xe
liquid liquid
gas
• ICARUS-UCLA • ITEP• Doke group (Japan) • DAMA
World expertise
• UKDMC• Columbia
July 2001 Neil Spooner
Boulby Xenon ProgrammeBoulby Xenon Programme
ZEPLIN-Isingle phase
PSD4 kg
ZEPLIN-IIion-scint
two phase Xe30 kg
ZEPLIN-IIIIon-scint
two phase Xehigh field
6 kg
ZEPLIN ZEPLIN arrayarray
under construction
running
demonstrate basic discrimination with PSD - set first limits
basic ionisation-scintillation and high target mass- improve by x10 - UCLA concept
ionisation-scintillation and high field- ultimate discrimination, low threshold -
ZEPLIN-MAXion-scint
two phase Xe1000 kg
new (5 years)
A multinational programme
: Involved in programmes:
UCLA, CERN/Padova, Torino, ITEP, Coimbra, Columbia,
RAL, ICSTM, Sheffield
July 2001 Neil Spooner
UKDMC Xenon - ZEPLIN IUKDMC Xenon - ZEPLIN I
Xe*
+Xe
Xe2*
Triplet27ns
Singlet3ns
2Xe2Xe
175nm175nm
Xe** + Xe
Xe2+
+e-
(recombination)
Xe+
+Xe
July 2001 Neil Spooner
ZEPLIN I UndergroundZEPLIN I Underground
Pb shielding
Top of ZEPLIN I veto
Boulby stub 2 laboratory
xenon purification
Stable operation demonstrated
Counts vs. time
Xe temp vs. time
room temp vs. time
July 2001 Neil Spooner
ZEPLIN Operations at BoulbyZEPLIN Operations at Boulby
July 2001 Neil Spooner
ZEPLIN I Laboratory testsZEPLIN I Laboratory tests
• Compton veto (1 ton PXE) found to have ~50 keV threshold
• PMT background events rejected by turret fiducial cuts as expected
137Cs eventsorigin is where all 3 PMTs
record identical signals
turret events rejected by asymmetry cut
July 2001 Neil Spooner
• Light collection exceeds design spec of 1 pe/keV
pe/keV
keV0
1
2
Z I data
theory
• Up to 50% difference in neutron and gamma time constants
tau (ns)
500 1000 1500 20000
0
50
0 20 40 60 80 100
keV
ZEPLIN I Laboratory testsZEPLIN I Laboratory tests
July 2001 Neil Spooner
ZEPLIN I DiscriminationZEPLIN I Discrimination
QuickTime™ and aGIF decompressor
are needed to see this picture.
QuickTime™ and aGIF decompressor
are needed to see this picture.
Gammasource
Neutronsource
10-20keV 20-30keV
(ns)
(ns)
n
July 2001 Neil Spooner
ZEPLIN I - Results ZEPLIN I - Results
85Kr < 10-17 atoms/atom
Predictions for 1 year
July 2001 Neil Spooner
• Light Yield– Increases at low energy
• Spatial Uniformity– 137Cs Source
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0 500 1000 1500 2000
E (keV)
dE/dx (Emax)
dE/dx (Eav)
Z-I data
Doke parameters:
h = 0.16, C = 0.51
S2 = .0097/.00032
12
3
45
6789
1011
1
1.5
2
2.5
3
3.5
4
0 1 2 3 4 5 6 7 8 9 10 11 12
Spatial Uniformity of ZEPLIN I
Light Yield (keV/p.e.)
Light Yield (keV/p.e.)
Source Position
Under PMTs Side BeamsIn CentreBetween PMTs
Data
Theory
ZEPLIN I Laboratory testsZEPLIN I Laboratory tests
July 2001 Neil Spooner
ZEPLIN I - Predicted LimitsZEPLIN I - Predicted Limits
July 2001 Neil Spooner
ZEPLIN IIZEPLIN II (UKDMC collaboration with US and Italy)
• Completion due end 2001
cooling ringsPTFE cone
OFHC copper plate
shielding, integration, readout, daq
UKDMC
~30kg Lxe detector
UCLA, Torino, Padova
ionisation-scintillation discrimination
July 2001 Neil Spooner
ZEPLIN III ZEPLIN III ionisation-scintillation - low threshold
• 6 kg liquid Xe
• High field (20 kV) operation for better discrimination
31 two-inch photomultipliers
Xe
• Completion due end 2001
(UKDMC collaboration with US and Russia)
1kg test chamberresult
July 2001 Neil Spooner
ZEPLIN-MAX A BDMC multinational programme
• Final design by mid 2002• Recoil Discrimination• Construction 2004+
Options being explored:(I) single unit, (II) 4 units, (III) modular(IV) mass + low threshold units
RESULT: (a) attain 0.0001/kg/d, (b) diagnostic array with complementary techniques
3 modules
80 kg target
4 sub- units
shielding
One possibility
ZEPLIN - 1 ton ConceptZEPLIN - 1 ton Concept
July 2001 Neil Spooner
PMT Removal for Scale-Up?PMT Removal for Scale-Up?
Liquid Xe
Xe Gas
HeCooling
GEMs
CsI
PTFEReflector
CsI
FieldShapingRings
nucl.rec.
elec.rec.
CsI photocathodes in LXe: E.Aprile, NIMA 338 (1994), 328; NIMA 343 (1994), 121.
GEM phototubes in noble gases:http://gdd.web.cern.ch/GDD/A.Buzulutskov, NIMA, 443 (2000), 164.
• Sheffield test cell
July 2001 Neil Spooner
GEM Prototype TargetGEM Prototype Target
High or low field operation
In-house CsI photocathode production
GEMs of Sheffield design from CERN
July 2001 Neil Spooner
GEM RigGEM Rig
July 2001 Neil Spooner
ZEPLIN locations at BoulbyZEPLIN locations at Boulby
Stub 2
ZEPLIN-I
ZEPLIN-MAX
ZEPLIN-III
ZEPLIN-II
JIF Facility
July 2001 Neil Spooner
NaI 1996 limit
ZEPLIN 2002/3
ZEPLIN I/II 2003
ZEPLIN II/III 2004
10-3
10-4
10-5
10-6
10-7
10-8
10-9
10-10
10 100 1000
WIMP-nucleoncross-section, pb
WIMP mass GeV
CDMS II
CRESST II
ZEPLIN-MAX 2006
ZEPLIN predictionsbased on prototype tests and operation of ZEPLIN I
ZEPLIN-XENON Predictions ZEPLIN-XENON Predictions
July 2001 Neil Spooner
DIRECTIONAL ProgrammeDIRECTIONAL Programme
• Q: What else can we do to identify a WIMP signal?
• A: We can be more cleverWe can be more clever: : S(A,ES(A,ERR) is in fact also function ) is in fact also function
of recoil direction due to of recoil direction due to earth’s motion through DM earth’s motion through DM halo. => halo. => Search for diurnal modulation to signal in directional detector.
6
600
~30 kms-1
~220 kms-1Sun
Earth
Jun. 2nd
WIMPWIMP
S(A,ES(A,ERR) => S(A,E) => S(A,ERR,,) ~ exp(-((v) ~ exp(-((vEEcoscos - v - vminmin)/v)/v00))22))
D.N. Spergel, Phys. Rev. D 37 (1988) 1353
July 2001 Neil Spooner
WIMP “wind” (at Boulby)WIMP “wind” (at Boulby)
July 2001 Neil Spooner
Galactic Halo ModelsGalactic Halo Models
UKDMC simulated directional data for standard halo
UKDMC simulated directional data for elongated halo (vz = 170 kms-1)
• If a signal is seen then we can probe galactic halo parameters
--> CDM streaming, infall, halo sphericity, co-rotation
July 2001 Neil Spooner
DRIFT Project DRIFT Project
MWPCOccidental
TempleSS vacuum vessel with internal
Cu shielding, access flanges and silica calibration windows
vesselUKDMC
The DRIFT-1 detectorThe DRIFT-1 detector
1.1 m
Multi-Wire Proportional Counter Readout
field cage
Gas and data
UKDMC
(UKDMC collaboration with US)
July 2001 Neil Spooner
DRIFT ConceptDRIFT Concept
• New technique - Directional Recoil Identification From Tracks (DRIFT) uses low pressure (40 Torr) CS2 gas.
• CS2 soaks up charge and carries it to read-out plane as CS2
-.
• High mass of ions limits transverse diffusion to < 1mm over 1m drift distance!
• No need for magnet.
• Discriminate with track-length.
CSCS22 gas gas
EE
CSCS22--
ions driftions drift
SS
MWPC
July 2001 Neil Spooner
DRIFT ConceptDRIFT Concept
Negative Ion Drift
An old idea
E.W McDaniels et al., RSI 28 (1957) 864H.R. Crane et al., RSI 32 (1961) 953
E
CS2-
ions drift
Xe
WIMP
anode MWPC readout
cathode
• Longitudinal and transverse diffusion of ions is much less than for electrons
--> typically < 1mm per m
• No need for magnet
• Readout by conventional MWPC
• Use CS2 + Ar, Xe at 10-80 Torr
• Electrons from ionised tracks reversibly attach to CS2 and drift to anode
July 2001 Neil Spooner
• DRIFT: low pressure gaseous TPC– Recoil direction correlation– CS2 minimises diffusion
• 1 foot cube detector @6keV– 99.9% gamma rejection– 95% alpha rejection (from wires)
• DRIFT 1m3 Module under construction– 200m wire chamber 2cm pitch– 20m MWPC readout 2mm pitch
• CS2+Xe,Ar at 10-80 Torr
DRIFT DesignDRIFT Design
gammas
recoil discrimination
C recoils
S recoils
gammas
recoil discrimination gammas
alphas
S recoil region (>90%)
alpha discrimination
July 2001 Neil Spooner
DRIFT-1 Integration at SheffieldDRIFT-1 Integration at Sheffield
vessel
July 2001 Neil Spooner
1 m
DRIFT-1 DetectorDRIFT-1 Detector
July 2001 Neil Spooner
DRIFT-1 Integration at SheffieldDRIFT-1 Integration at Sheffield
July 2001 Neil Spooner
DRIFT-1 Predicted limitsDRIFT-1 Predicted limits
Full background audit for DRIFT-1 completed (tests and MCs)
a background of ~ 5 counts per year per m3 is feasible
• DRIFT-1 can yield a limit below DAMA
CONCLUSION
• DRIFT-1 could just detect a directional signal at 10-5 pb
3 m3yr
30 WIMP events
80 WIMP events
July 2001 Neil Spooner
DRIFT 1 site
Installation Aug 01
Part of 1500 m2 new facility at Boulby - 3000 mwe depth
DRIFT 1 - Installation Aug 01 DRIFT 1 - Installation Aug 01
July 2001 Neil Spooner
DRIFT module - low cost materials
15 cm removable, low costPb shielding
CS2 manifold and storage
3 m
DRIFT-10, towards 1 ton a BDMC - multinational programme
--> need 1 ton to get enough counts at minimum SUSY
DRIFT-1
DRIFT-10
1 ton
CS2
Xe
DRIFT-MAX - 1 Ton gasDRIFT-MAX - 1 Ton gas
July 2001 Neil Spooner
SummarySummary
• DAMA NaI annual modulation as objective
WIMP or fluctuating low energy noise?
• UKDMC ‘anomalous events’ as surface alphas?
Seen in Saclay (DAMA) crystal
• CDMS recoil limit (almost) excludes DAMA
Subtraction of neutron signal
• Several detectors becoming sensitive at 10-6 pb
• Many more direct searches underway to reach ≈10-8pb
• Indirect searches reaching sensitivities to exclude models
WIMPs (10-9(or -12) pb < scp < 10-6 pb, 50 GeV < m <600 GeV)