1snolab 21 august 2006 zeplin a direct dark matter search programme using liquid xenon cclrc –...

1SNOLAB 21 August 2006

ZEPLIN A Direct Dark Matter Search

Programme using Liquid Xenon

CCLRC – Rutherford Appleton Laboratory, UKEdinburgh University, UKImperial College London, UKITEP – Moscow, RussiaLIP – Coimbra, PortugalRochester University, USASMU, USATexas A&M University, USAUCLA, USA


The Programme

• ZEPLIN I* – completed/published• ZEPLIN II* – taking quality dark data• ZEPLIN III – ready for immediate deployment• The future – clear route to tonne scale through

international collaboration

• Technical progress Report – ZEPLIN II/III – Tim Sumner

• Technical progress Report – ZEPLIN IVby4 – Hanguo Wang

• Infrastructure & Strategy

• Schedule

* Collaboration on these projects includes Sheffield University, UK


World Status


World Status

tonne scale target

ZII, ZIII


Two-Phase Xenon Principles


ZEPLIN II

• Continuous operation for last 100 days with 7day/week support of whole collaboration

• It is working well• Its performance is

understood• It has collected quality

dark matter data

…some examples


ZEPLIN II

Purity


ZEPLIN IIScatter plot


ZEPLIN IIPosition recovery(from S2)


ZEPLIN IIDark Matter Data• 1.0 tonne.day of quality data collected• 0.1 opened for unblinded analysis• Version 1 data cuts defined • Efficiencies evaluated

zero background in nuclear recoil band (to be confirmed)1.35x10-6 pb

1.35x10-7pb* in current data set Publication intended for IDM2006

• Version 2 cuts + clean lower energy + larger fiducial volume (lower background/better position recovery)

• April 07 3 times current exposure

* Assumes 0 bg – data not opened yet

Preliminary

Preliminary


ZEPLIN II ZEPLIN III


ZEPLIN III Features• 8kg fiducial mass• High QE PMTs in liquid for excellent light

collection• 3.5 cm drift depth• 0.5 cm electrode-less electroluminescent

gap for improved discrimination• reverse field region• 31 small PMTs for fine position sensitivity• open plan – no surfaces - reduced

feedback• Copper construction


ZEPLIN III Status • Built and tested

• Performs as designed

• Journal papers– Simulation – Araujo et al. (2006) Astropart. Phys. In press

– Instrument – Akimov et al. (2006) Astropart. Phys. In revision

• Vital experience and momentum gained from ZEPLIN II

• Ready for immediate deployment

DM2006 - February 2006


Commissioning Tests

0

20

40

60

80

100

120

140

160

0 500 1000 1500 2000 2500

PMT00

PMT02

Thermal design verified – 1litre/hour LN boil off!

All PMTs operational – spe established – gains equalised

Xenon transferred several times Extended runs of up to 8 weeks Am241 spectra obtained with up to

16pe/keV – a world best! Dual-range 62 channel DAQ readout Data processing and analysis system

developed HV established Full-depth two-phase signal recovery Bulk light yield established Neutron calibration done


5 pe/keV

- 3.5 x ZII

Bulk light collection, S1

Charge collection, S2


SUM [H00-H30], SUM 10x[L00-L30]

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

time, ns

am

pli

tud

e,

V

HS

LSx10

CHANNELS [H00-H30]

-6.5

-5.5

-4.5

-3.5

-2.5

-1.5

-0.5

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

time, ns

amplit

ude, V

Position recovery


Neutron calibration

ZEPLIN III ZEPLIN II


Araujo et al., 2006

Sensitivity prediction


ZEPLIN II

ZEPLIN IV/MAX 0.250 ton

ZEPLIN III

30kg

8kg

ZEPLIN long term strategy I

+ =


Direct Scale-up Based on the ZEPLIN II/III

250kg

250kg fiducial mass Two phase xenon 50 5-inch-PMT

19 (7 eight-in) on bottom31 on top

30-cm total drift length Light yield ~ 4pe/keV 45kV @ E=1.5kV/cm Xenon Purification

Forced Circulation

in liquid phase (system being studied)

Active liquid recovery ~R x H = 0.5 (m) x 1.0 (m)

No R&D needed for this design!


Spatial separation of double scatter (S2)

background events in drift direction

Self Shielding

Fiducial Limit

µs


“Club54”

250kg

500kg fiducial mass Two phase xenon 50 5-inch-PMT

19 (7 eight-in) on bottom31 on top

60-cm total drift length Light yield ~ 4pe/keV 90kV @ E=1.5kV/cm Xenon Purification

Forced Circulation

in liquid phase (system being studied)

Active liquid recovery ~R x H = 0.5 (m) x 1.3 (m)


Neutron sources

• Neutron production from

– U/Th in detector material

– U/Th in shielding material

– U/Th in rock

– µ spallation in detector material

– µ spallation in shielding material

– µ spallation in rock


250kg detector


VI

Xe Target

VII

Xenon Purification and Safety System for ZEPLIN IV

VI, VII, are vacuum pumpsActive Xenon collection system will take less space (1.4 x linear size)Xenon purification in liquid phase (less cooling power)

Manual Valve

Cooling

Pum

pG

ette

r.

SafetyDump

Cooling

Vacuum Insulated LineC.B.

C.B. Control Box

For

ced

reci

rcul

atio

n

syst

em


ZEPLIN IV/MAX layout

1, Target Detector: (250kg ton scale) 8m x 8m x 6m (WxLxH)Central detector, Active neutron and Compton vetoLead shield, Neutron Shield.

2, Electronic & Control: 5m x 4m x 3mDAQ system, Slow control,

3, Auxiliary systems: 8m x 8m x 4m

Active xenon recovery system and related pipe-works and controls

4, Total Peak Power 25kW

5, Office


(ZEPLIN III+IV/4)

ZEPLIN IVby4FY07 Engineering Design

(SNOLAB Invitation for Tech. Design)

FY08 Start Construction

FY09 Underground Installation

Total US Construction $3.5M + equivalent European contribution

ZEPLIN IIIFY07 Deployment/Operation

Requires shield plus veto

and local collaborators

FY08 Upgrade/operations (PMT, depth)

FY09 Completion

Canadian collaborators are very important to both instruments at SNOLAB

tonne scale target

ZII, ZIII


Summary• ZEPLIN II is working with >1000kg-days data on tape.

• First limit is encouraging

• Routine electron lifetimes > ms

• Analysis cuts defined

• More data to come with reduced background and improved analysis lower threshold/larger fiducial

• ZEPLIN III is ready to go and performs as designed.

• Bringing ZEPLIN III to SNOLAB provides an early science result from an existing detector and paves the way for ZEPLIN IVby4

• ZEPLIN team is well versed in ‘mine’ operation/usage

• Combining Zeplin II&III and Xenon10, (Club54) we know the next step to 10-10pb (500kg) – looking for Canadian involvements

1snolab 21 august 2006 zeplin a direct dark matter search programme using liquid xenon cclrc –...

Documents

zeplin iiready

data cuts

quality data collected0

ukedinburgh university

portugalrochester university

sheffield university

bg data

quality dark datazeplin