1. MICE Target Failure UKNFIC Meeting Adam Dobbs - when and why 4 th July 2008

2. Outline Manifestation of problem Post mortem examination Causes and evidence Remaining questions New target

3. Date of Failure 4/7/20083Adam Dobbs UKNFIC Meeting4/7/2008Adam Dobbs UKNFIC Meeting3 Failure of the MICE target occured between 19th Dec 08 to 21st Dec 08 First manifested as as inability to reach beam loss levels of 500mV in ISIS on 19th – something which previously had not been a problem On 21st target jammed and became unusable

4. Target Examination Tip melted, loss of ~8mm in length of target Target shaft bent, 10 0 from vertical 4/7/2008Adam Dobbs UKNFIC Meeting4

5. Cause of melting 4/7/2008Adam Dobbs UKNFIC Meeting5 On 29 th Nov 08, between 14:30 and 15:30 the target was left in ISIS beam due to operator error It was wrongly reported to ISIS that target was clear Subsequently ISIS continued to experience trips, which were repeatedly reset (subsequent analysis ⇒ need 12 pulses for target to melt, ISIS trips after 3) After this target running resumed

7. Beam Loss data for 29 th Nov 08:

8. ~8mm Target depth view:

9. Total beam loss vs Target Depth vs macro Time:

10. Cause of jamming 4/7/2008Adam Dobbs UKNFIC Meeting10 Collar added here Collar fell off shaft when lower bearing removed during post mortem ⇒ Collar came lose causing jamming of shaft

11. Remaining Questions Is there a link between the jamming and the melting? What caused the target shaft to bend – again could the melting be responsible? What caused the observed wear on the lower part of the shaft?