drift-iii proposal for a large scale directional dark matter detector @ snolab

SNOLAB-2005 Sean Paling - DRIFT

DRIFT-IIIProposal for a Large Scale

DirectionalDark Matter detector @ SNOLAB

Sean Paling - Sheffield University

For the DRIFT Collaboration: Occidental College, University of New Mexico, Boston University, Imperial College, RAL, Sheffield, Edinburgh (UK Dark Matter Collaboration - UKDMC)


DRIFT-III: Phase ONE

Extension of current DRIFT-II programme @ Boulby mine.

An array of 10 low-pressure Negative Ion DRIFT TPC modules (≤10 kg target

mass, 10-8pb raw sensitivity)

DRIFT-II@Boulbymine

DRIFT-III phase ONE

Proposal: House phase ONE of DRIFT-III

@ SNOLAB

1st step & test-bed for scale-up to DRIFT-III - a 100+ module 100kg directional detector 10-9pb (raw) and 10-7/8 (directional) sensitivity

Will discuss:

• Motivation & concept

• Progress so far (DI/DII)

• DIII-phase ONE details &

requirements


Why a Directional Detector?

12:00h

42o

0:00h

WIMP Wind

Galactic WIMPHalo

To provide THE most powerfulsignature of the existence WIMPs in the

galaxy - through unambiguous measurement of the WIMP wind.


Moore et al.....Clumps

Tidal disruption streamsStiff et al..Freese, Gondolo et al.

Sun’s influenceFu-sin Ling et al.Sikivie, Wick et al

Sagittarius Stream - Freese et al.

No longer just the simple spherical, Isothermal Halo...• velocity space anisotropy• bulk rotation• substructure, clumps• triaxality, oblate vs. prolate• late accreted sub-halos• sub-structure on sub-pc scales• spikes and caustics

Later - WIMP Halo studies

Study the structure & dynamics of the Dark Matter Halo

WIMP arrival distributions

Spherical Isothermal

Tidal StreamLogarithmic Ellipsoidal

Different models produce different WIMP arrival directions/velocities

(B. Morgan, A. Green, N. Spooner - Astro-ph/040804)


How to build a directional How to build a directional detector?detector?

DRIFT: A Low Pressure Negative Ion Drift TPC

(NITPC)Low Pressure TPC:• Low pressure target extends range of

WIMP nuclear recoils to a few mm.• 3D reconstruction possible by

combining 2D readout with signal timing analysis.

Negative Ion DRIFT:• Electron capture by electronegative

gas reduces track diffusion.• Diffusion of <0.5mm at 0.5m drift

length (1000v/cm)Electric Field

Scattered WIMP

Recoil Atom

Drift direction

MWPC Readout

Plane

Cathode

CSCS22

Problem: In solid or liquid targets <100keV recoil tracks ~ 1-100nm long

The DRIFT Concept

(Rediscovered by Martoff - Temple)


DRIFT Backgrounddiscrimination• Based on signal ENERGY and

RANGE.• Nuclear recoils have a higher dE/dx

than background electrons or alphas.Gammas

Alphas

Nuclear Recoils

• Little / no gamma shielding!

• Competitive as hi-sensitivity, limit-setting detector.

The DRIFT Concept

Gamma discrimination of >106 so far demonstrated.

(Snowden-Ifft et al. NIM A 498 (2003), & - Kirkpatrick et

al, in preparation)


167g Target (1m3, 40 Torr) (20 keV threshold)

Scale up: 100kg (10keV theshold)

Xe Enhancement: (50% Xe/CS2) (10keV threshold)

How Sensitive?

61 kg.d no events

36,500 kg.d no even

ts

36,500 kg.d no even

ts

Single DII module1 year

100kg DIII 1 year

(Preliminary)

100kg DIII 1 year50% Xe:CS2

Adding Xe potentially…• Increases sensitivity by factor ≤5• Greatly assists verification of +ve wimp signal (proprotion of Xe to C/S recoils) (P.F.Smith et al, Astroparticle Phys 22, 2005)


Simulations for realistic (advanced) NITPC Detectors…• 40 Torr CS2, 1 kVcm-1 drift field• 200 mm resolution, 10 cm drift• SRIM2003 - recoil scattering and diffusion

40 keV S recoil in 40 Torr CS2 (SRIM)

Results depend on: (1) Halo Model(2) Reconstruction accuracy

(Can we tell the ‘sense’ of the track? - Head or Tail?)

IF recoil sense known 10-20 events needed, if unknown 100-400 events needed - to reject isotropy at 95% confidence in 95% of experiments.

What about ‘Halo’ Sensitivity?

How many WIMPs to verify directionalHalo signature?

(B. Morgan, A. Green, N. Spooner - Astro-ph/040804,also: B. Morgan, A. Green - in preparation).

‘Halo sensitivity’ is between factor 10 & 100 behind raw detection sensitivity (depending on halo model and detector technology).


DAMA

1000 GeV100 GeV

mssmRoszkowski et al.

Edel II, CDMS II, Zep II, DRIFT-II..

scale-ups

1 ton

100 ton

~1 event/100kg/year

~1 event/10ton/year

2003

2006

2010

2020

Edel I, CDMS I, Zep I, DRIFT-II..

No signal Signal found

10-6

10-7

10-8

10-9

10-10

10-11

10-5

10-12

Pb

100kg DRIFT & the World DM Search

Next Steps:Galactic confirmation- directionalityhalo studies

DRIFT-III

Detectionsensitivity

Halosensitivity

DRIFT-IIIPhase ONE


The DRIFT Programme

2000 2001 2002 2003 2004 2005 2006 2007

1997-2002: Concept development, gas tests,

simulations 1ft3 NITPC prototype studies.

DRIFT-I: 1m3 (167g) NITPC.

Development, installation/operation

@ Boulby

DRIFT-II: 3(+) 1m3 (0.5-2kg) NITPC

Development, installation/ operation

@ Boulby

Scale-up R&D: Simulations, readout,

reconstruction, cost, engineering.

Surf commission - Sheffield

Install (May 05))

Operation

Surf commission - Oxy

Install (Jan 02))

Operation

Boulby Mine (UK)2805 mwe

DRIFT-II, Phase ONE (10 modules): Installation

2007/8


DRIFT-I

• 1m3 Dual Negative Ion DRIFT TPC• 1.4m3 vac vessel - 40 Torr CS2 (167g fiducial)• Back-to-back 0.5m3 DRIFT regions.• MPWC readout (512 20m anodes, 2mm pitch)• DAQ: 2512 chan 1S sampling.

Installation 2001/2, Operation 20022004

DRIFT I: 1st large-scale DRIFT detector.

MW

PC

layout

DR

IFT-I @

Boulb

y

UKDMC, Occidental, Temple


DRIFT-I

Outcomes• Demonstration of safe, stable, long-term operation UG .• Demonstration of event characterisation/discrimination.• Measurement of rock neutrons• Early verification of high gamma discrimination (>106)

Alner et al, NIMA, 535 (2004), Kirkpatrick et al (2005) - in preparation

Status• Some technical/engineering difficulties (DAQ, MWPCs, Fatigue). Moved on to apply numerous design/engineering lessons learned to DRIFT-II


DRIFT II

Advanced, multi-module (3+) detector with sensitivityof ~10-7pb. Using lessons from DI and R&D.

• Aim:

(Factor 5 cost-reduction per module vs. DRIFT-I)

DR

IFT

-IIa @

Bo

ulb

y

1st step toward large scale multi-module upgrade

• Basic Design

• 3(+) 1m3 fiducial vol, NITPCs

• Back-to-back drift vols, dual MWPC readout

• Vertical planes, Warp adjust strongback MWPCs

• Improved (3d) track reconstruction (anode, grid and z-drift) (resolution: 2mm(x), 0.1mm(y), 0.1mm (Z))

• Low noise / cost 0.5S sampling (grouped) DAQ

• Improved vessel design (<10-8T.L.s-1) .

• Improved gas system (varied gas pressure & mixtures)

Robust, simple, reproducible & cost-reduced…


DIIa - Construction & Commissioning

Side-oriented back-to-back field cages with rigid Cu piping.

1.5m3 cubed stainless steel vacuum vessel (UK/USA)

MWPCs, 512 20um anode wires: lucite frame with warp-adjust bars

Grid amplification & grouping, prior testing.

Inner detector stack

November 2004


Boulby Mine - The JIF Area

Dark Matter ‘JIF’ Area

Stub BStub A

Low BGLab

>2.0m

ZEPLIN - II

>2.0m

123

ZEPLIN - III

Exhaust CS2 sensor Data acquisitionsystem

Detectors / VacuumChambers

gas systems, fume hood & extraction hose

DRIFT-I Lab

Mess

Gas/fire sensorcontrol

Entrancecorridor

CS2sensor

Late 2004

~100m

>1500m2 floor space (5m3.5m cross section)2T full XY craneCommunications, workshopStorage, clean room

DRIFT-IZEPLIN-II

DRIFT-II

Boulby Mine (UK)2805 mwe


DRIFT II Status (July-Aug 05)

Construction/installation of modules b & c underway (full operation early 2006)

Next steps: - erect 40g.cm-2 neutron shielding (Polypropylene pellets in wooden support structure).

(Completion this week - followed by start of running shielded)

DIIb

DIIa

Gas / vacuum system tests. Neutron, alpha, gamma/X-ray calibrations, directed neutrons (directionality).• Demonstrated long term operation & stability (5 weeks continuous running - for pre-shielded data).

DIIa - fully installed, underground commissioning complete.


Towards DRIFT-III (100kg)

Phase ONE (2006/7):1st 10 detectors:101m3 (fiducial), 40-240Torr (up to 10kg), 10-8pb raw sensitivity per yr.- forerunner to full extension of array.

This proposal

• Site/technology constraints on size.• Allows staged construction/installation• Minimises down time• Module comparisons (diagnostic. array)• Variable configuration/siting.• Cost (etc) benefits of mass production.

Why multi-module?

DRIFT-III Concept:

• Mass Production of 100(+) advanced, robust, reliable, stable & safe, NITPC modules. • 100kg total fiducial mass, 10-9pb (10-7/8pb) raw (directional) sensitivity (per yr).• High resolution 3d readout, high pressure (≤240 Torr) CS2 (or other).• Time-scale: Installation 2010?

DRIFT-III


Scale up R&D

Minimize costs

‘head-tail’ discrimination

Improved resolution readout.

10(+) better directionality

higher pressure - lower volume

‘Z fiducialisation’

Alternative gases/mixture Increased sensitivity, WIMP signal verification

Specific technical R&D issues:

Improved track resolution, BG rejection.

Optimizedesign /

performance

DRIFT-III R&DReduceBackgrounds

(Micromegas? GEMs? <50µm? - UKDMC, UNM)

(Cathode readout, diffusion - Oxy)

(Xe:CS2 mixture, CF4, etc - UKDMC/Oxy)

(Bragg curve of recoiling ions? - Boston, UNM, UKDMC)


Costs

AIM: further reduce costs (through MASS PRODUCTION) to ~£20K (<$40) per unit inc. shielding

If successful: <£2-10M (material/equipment) for 100kg.(~£0.2M for DRIFTIII-phase ONE)


Background reduction

M. J. Carson et al. Astropart. Phys. 21 (2004)J. Davies et.al, NIMA, 546 (2005)

DRIFT-III Neutron Background Simulations

Neutron background source excluding muons

Recoil yr-1

(10-50 keV)

Rock unshielded, and shielded by 60 g/cm2 CH2

1.6106, 0.03

Stainless vessel, and after internal 10 g/cm2 CH2

25, 0.4

All internal components (resistors etc.)

0.2

CH2 shielding itself 0.2

Total expected in detector with shielding

<1

GEANT4 (FLUKA & SOURCES)

Neutron (excluding muon-induced)For 100kg DRIFT @ Boulby

Muon-induced Neutrons @ Boulby ( 2805 MWE) n >50

DRIFT-III needs greater depth to avoid costly muon-veto...

@ SNOLAB (~6010mwe) n <1


Size/space needed?

10 1m3 (fiducial) detectors (1.5m3 vessels), 50-60gcm-2 CH shielding,

Need ≤30m of tunnel - 3.3m cross section (inc gas system, staging, storage & control)

DRIFT-III phase ONE

Size/arrangement dependent on location.

Size dependent on technology and location.e.g: in a large hall - stacked design, ~2000(+)m3 needed.e.g: In a ‘corridor’ - linear design : ~300(+)m of tunnel with 3.3m cross section…

D-III could be split - more than one lab or UG site!

NEW areas dug? - cost of excavation @ Boulby estimated

>£1.M for 200m tunnel

Later scale-up: DRIFT-III (100+ detectors)

Is size a problem long term? - Not necessarily:


EmergencyEgress

Large ExperimentalSpace

Utility Area

Smaller Drifts

DIII Phase ONE

SNOLAB Ladder Labs…

<30m

2 banks of 5 shieldeddetectors, gas system,

DAQ,storage/staging30m (3.3m2 cross sec)


General facilities: • Transportation:10 detectors + vessels, support apparatus, 100T PP shielding.• 2T lifting capacity (crane/forks?)• ≤ 30m2 staging/material storage space. Moderate class clean room (<class 2000).• Power: 500W single phase per module (>10kW for 10 & support apparatus).• Light use of mechanical & electrical workshop• Moderate temperature stability (+/-2C)

Special requirements:• No cryogenics, vibration control, laser & optics, water purifcation. • Radioactive sources: Small (C) neutron. gamma & Alpha calibration sources.• Gases/Chemicals: Reduced CS2 quantity (sealed?). <15kg max.

Health & Safety:Main issues = CS2 target gas (100kg) and use of High Voltage.

By necessity for scale up (mass production / installation)DRIFT- III phase ONE = robust, stable, safe, low maintenance, low cost - low demand on infrastructure/services

Other Facility Issues

Proven safety record: No incidents in over 3 years operation @ Boulby

Fully compliant with stringent Boulby safety system (PIP). Comprehensive risk assessments, procedures, change control documentation produced & maintained.

DII safety documentation


Funding & Schedule

Schedule:2005-7 DRIFT-II operation and scale-up R&D2006/7 Design development / review. Site preparation, 2007/8 Staged construction, installation, operation.2008+ Full operation, evaluation/R&D for upgrade to DIII2010? Staged installation of DRIFT-III.

Funding:• Estimated total cost. ≤£1M (eqpt, staff, R&D) - over 3-4 years.• DRIFT program currently funded by NSF (in US) & PPARC (in UK). European funding also becoming available.• Specific applications for DIII phase ONE will be submitted 2005/2006

DRIFT III phase ONE


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A directional detector could provide THE most powerful signature for existence of WIMPs in the galaxy - DRIFT is far ahead of the pack in developing directional detector technology.

Now looking towards extending current programme to produce a large-scale 100kg detector (DRIFT-III) - giving 10-9pb (raw) sensitivity per year. Complement & compete with next non-directional detectors.

Phase ONE @ SNOLAB? - a REALISTIC 1st step in this upgrade: 10 modules with mass of up to 10kg and raw detection sensitivity 10-8pb per year. Forerunner to later upgrade.

DRIFT Technology = low maintenance, low impact on facility requirements. Low risk - proven record of safety & delivery at Boulby mine.

Summary


DRIFT-IIIProposal for a Large Scale

DirectionalDark Matter detector @ SNOLAB

Sean Paling - Sheffield University

For the DRIFT Collaboration: Occidental College, University of New Mexico, Boston University, Imperial College, RAL, Sheffield, Edinburgh (UK Dark Matter Collaboration - UKDMC)

Join us?

drift-iii proposal for a large scale directional dark matter detector @ snolab

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