1. Detector Decommissioning Related Activities at DØ George Ginther Fermilab and University of Rochester 23 January 2012

2. Secure and Stabilize Recent Events Routine recording of cosmics ended before 0730 on Thursday 22 December Began warm-up of Silicon Microstrip Tracker –Raised chiller setpoint to 16C –Recording IV curves and monitoring annealing of Layer 0 sensors Ramped down muon chamber high voltages Shutdown of muon chamber gas systems Powered down Level 1 Calorimeter Trigger system North dry engine failed during the early morning of Friday 23 December –East dry engine not able to keep up with demand –Liquid helium inventory dwindling –Started warm-up of solenoid early to reduce demand on helium 2

3. More Recent Events Blown fuse in ODH system closes valves on calorimeter during the early morning of Saturday 24 December LCW pumps off and system drained Disconnected solenoid and toroid power supplies Powered down Silicon Track Trigger Collision hall permit (intentionally) dropped –Transition to supervised access mode Configured detector to allow access to pump down vacuum jackets on liquid argon transfer lines Power down lumi system 3

4. Even More Recent Events Ramped down calorimeter high voltages and terminated calorimeter bias current monitoring Transferred 11100 gallons for liquid argon to underground storage tank Recondensing residual argon as it evaporates from the calorimeters Drained liquid helium inventory Shutdown liquid helium plant Began warm-up of Visible Light Photon Counter cryostats (readout for Central Fiber Tracker) –Turn off VLPC bias and temperature control Turned off VLPC cryostat lid heaters Powered down Level 1 Muon and Central Track Trigger systems 4

5. Next Steps Start purge on VLPC cryostats –Verify cold block above dewpoint –Extract a cassette from the east cryostat and install a blank with purge inlet –Replace a blank on west cryostat with a blank equipped with purge inlet Power down Central Fiber Tracker readout Power down Calorimeter readout Complete rad survey of collision hall to update postings 5

6. As conditions (and resources) permit Power down rack infrastructure Continue preparations of online computing cluster for transition to offline cluster –Identify, backup and archive critical information Shut down silicon chiller and purge system Drain Deionized Chilled Water detector systems and purge Decommission Trane Chiller Secure halon fire suppression systems Continue high bay preparations Continue harvesting components for re-use Continue preparations for basic exhibit 6

7. Clean Out and Harvest The mechanical crew is well into the process of preparing the DØ Assembly Building high bay to accommodate MicroBooNE TPC assembly 7

8. High Bay 22-Nov-2011 8

9. High Bay 9-Dec-2011 9

10. High Bay 19-Dec-2011 10

11. High Bay 16-Jan-2012 11

12. Preparing the Basic Exhibit Cleared north sidewalk area and moved current collection of artifacts into that area Next steps –Prepare for dismantling of concrete shield block wall Clear top of wall and dismount bus work as needed Support helium cryo lines Disconnect air handling units –Take down much of concrete block wall –Install barriers to control access to collision hall –Configure detector for exhibit Move north toroid onto sidewalk and open west central iron and move north end calorimeter back to expose gap –Aim to be ready with basic exhibit prior to Tevatron symposium in early June 2012 12

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16. Detector Decommissioning Summary DØ successfully collected supporting data samples during the post- collider operations period The detector is in the process of warming, being stabilized and secured Monitoring of SMT annealing in progress Making significant progress in preparing the Assembly Building to accommodate additional operations –High bay was ready for installation of MicroBooNE TPC assembly clean room well in advance of the project’s required milestone Anticipate resources will be sufficient to secure the detector and provide the basic detector exhibit in 2012 –Constraints generated by broader lab plans are being integrated into the decommissioning effort may impact the schedule This flexible plan should provide the opportunity to maximize the productivity of the lab’s staff while ensuring that the DØ detector is put into a safe and secure state and transitions into a valuable educational exhibit 16

17. DØ Mechanical Operations Team

18. DØ Operations SupportTeams PPD Electrical Engineering Department members Mike Cherry, Victor Martinez, Tim Martin, Mike Matulik, and Bruce Merkel also provide essential support Russ Rucinski Pete Simon Bob Barger John Najdzion Bob Kubinski Mike Sarychev Bryan Johnson Pat Healey Bill Frank