Status of COUPP Experiment in the

MINOS tunnelErik Ramberg

AEM4 February, 2008

COUPP Timeline• Spring, 2004: Installation of U.of C. bubble chamber as test beam experiment T945

• Dec 2005-Nov. 2006: First engineering run resulting in 250 kg-days exposure

• Nov 2006: E961 (60 kg chamber) granted stage 1 approval

• July, 2007-Nov. 2007: Physics run with low background vessel

• September 2007: Fermilab Wine and Cheese talk

• Dec 2007: Paper approved for publication in Science magazine

• December 2007: Move chamber to new location under muon veto

Data from 2006 Run

To be published soon in Science magazine.Data from pressure scan at two temperatures:

Solid lines:Expected WIMP response for

SD(p)=3 pb

Radon background

Energy Threshold In KeV

New Run of 1-liter Chamber• Inner vessel has been entirely rebuilt with materials believed to have lower radioactivity.

• New run started July 30, 2007.

• Some radon introduced during filling, now decayed to equilibrium - on the order of handful of events per day

Dec. 3, 2007: End of Current Physics Run Due to Acoustic Testing Unit Occluding

Camera View:

- Can still take data, with slightly reduced active volume- Decided not to open up chamber and spoil low background environment- At this point we decided to move the detector under the new muon veto array to determine muon induced background

KTEV hodoscopes were reused as COUPP -veto

-neutron flux likely dominated by rock radioactivity in a site this deep.

- Muon veto and 30 cm of polyethylene potentially allow us to reach <0.1 c/kg day

Neutrons in NUMI tunnel

Move of bubble chamber from previous location in MINOS tunnel hallway, to final location under

the muon veto

Many thanks to John Voirin, Russ Rucinski,

Todd Nebel

Efficiency of Muon Veto

Installed thick counter triggered by muon telescope

Efficiency of veto array with respect to ADC in thick counter -

Better than 95% efficient, with two nonworking top PMT’s

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.QuickTime™ and a

TIFF (Uncompressed) decompressorare needed to see this picture.

Started up run last week and obtained ‘Golden’ event:

• Muon veto coincident• NUMI beam signal coincident• Two bubble event• Observed several in first few days of running

NUMI Veto

Acoustic

Pressure

-3000 -2000 -1000 0 1000 2000 3000 Time (microseconds)

MEANWHILE:

- We are contructing a 15 kg chamber in Chicago

-and a 60 kg chamber here at Fermilab

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Current New water DAQ and setup tank veto control

The collaboration is now planning the installationof the COUPP 60 kg chamber in the MINOS hall.

One possibility is to build a water Cerenkov shield/veto for use in the NUMI tunnel that could then be transported to a deep underground site: