Status of COUPP Experiment in the MINOS tunnel Erik Ramberg AEM 4 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, 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

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 Time (microseconds)

MEANWHILE: - We are contructing a 15 kg chamber in Chicago -and a 60 kg chamber here at Fermilab

Current New water DAQ and setup tank veto control The collaboration is now planning the installation of 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: