DRIFT II & DTM recent work 2010/11

UK: Sheffield, Edinburgh, STFC

AIM: Directional Detection of WIMP Dark Matter - Identify a Galactic Signal

US: Occidental, UNM, CSU•New publications including

world’s best limit with direction sensitivity (unblind)N.J.C. Spooner et al. Astroparticle Physics 34 (2010) 284E. Daw et al, sub Astroparticle Physics (2011) - arXiv:1012.5796

Only DRIFT here also has directional sensitivitynext best directional is ~x1000 worse

•built and installed new gas system for CF4 (SI sensitivity)

•Built and installed upgrade to DAQ

•Key analysis of low background and radon reduction and emanation system

•Run all operations

UK work

Underway now•New blind analysis with x15

improved background to be released soon

47 day run with CS2/CF4

DRIFT IId new upgrade success at Boulby

Neutron

Background

0.9 μm film cathode

Neutron

Background

20 μm wire cathode

IWS-R

MST (

μS)

anode F recoil energy (keV)

anode F recoil energy (keV)

•New upgrade to thin (alpha transparent) cathode shown to suppress background by another x15-30Plot shows neutron calibration and

background from radon induced recoils before and after replacement of central

cathode New blind analysis imminent to set

improved limit/sensitivity

Directional DM Opportunities at Boulby

• Funding for the Boulby Palmer Laboratory secured for 3 years under STFC environment programme even though ZEPLIN has gone - a big opportunity for a re-newed UK effort

• The directional field is rapidly growing, now 5 groups: DRIFT, MIMAC, NEWAGE, DM-TPC, D3 worldwide (~150 scientists). We started the CYGNUS international cooperation (Boulby2007, MIT2009, Aussois2011)

• Five non-directional DM experiments have “backgrounds” above expectation - the directional sensitivity can provide a clearer signal identification and determine galactic origins - the UK can have a leading role

• NSF supports continuation at Boulby• Mine company CPL supports new excavation for scale-up

Workpackages: (1) gas, (2) background, (3) directionality, (4) halo physics

Context

Proceed to scale-up at Boulby to 24 m3called DTM (DRIFT III module)

The only UK-based particle physics experiment

Scale-up Design for DTM (DRIFT III Module) of 24m3

Field cage

cathode

Field cage

anode

• 3D readout with track sense

• US-UK design well advanced

UK current contributions: gas system, radon/background

reduction, slow control, shield, site, analysis and data

• 24 m3 4 kg target

• Modular to allow ton-scale • z-fiducialisation by +ve ion

detection and thin cathode • C, S, F targets to include spin

dependent sensitivity

current limitsDRIFT IId - 10 day run, zero

background prediction

DTM - 1 year run 4 kg.yr

DRIFT IId - 2.4 m3-years, zero background prediction

Sensitivity Estimates (SD)

electronics

DTM Boulby Location & CPL Cooperation•Site for first DRIFT III module

identified at Boulby•CPL willing to excavate for DTM with

in-kind contribution•Only simple infrastructure needed

Current Palmer Lab back entrance

to roads

scale drawing

40m

6m 6m

ExtensionDTM

6m

Main messages Despite the finances and thanks to strong support from the US and mine company DRIFTII is doing well though increasingly difficult for UK groups. We previously demonstrated directional capability in 1 m3 focussing more recently on background reduction and use of F target. This has succeed, allowing us to produce a competitive SD limit with no compromise on the directional sensitivity. This is unique. Our recent upgrade to a thin cathode to supress radon induced recoils has shown we can reduce this dominant background by x15. A new fully blind analysis based on this new data will be released in the summer for a new limit. The technique to z-fiducialise by +ve ion detection has been proved by UNM and will be installed next, plus a further upgrade of the cathode. The UK has recently been responsible for a complete upgrade of the DAQ. This will allow improved 3D reconstruction.

There is world-wide growth of interest, partly stimulated by several above-background results in non-directional detectors. There are now 5 serious directional groups with ~150 people (incl theorists) e.g. MIMAC is about to deploy in Modane., DM-TPC is in WIPP and NEWAGR in Kamioka. We have grouped together at a semi-formal level, called DARK-CYGNUS and developed joint work-packages. There is enthusiasm and an opportunity to go to the next step now at Boulby, with the site at least secured for 3 years and mine company CPL interested to help. The aim is to build DTM - 24m3. There is currently no direct STFC support.