A Tale of Two Targets … 7 th September 2009 Chris Booth The University of Sheffield

Target One Installed in ISIS – 25 th August Gate Valve opened, target and frame controls checked out – 27 th August Delays adjusted, readout calibrated – 2 nd & 3 rd September 2

Calibration run with frame raised. Frame lowered, preliminary depth & delay scans to find edges of the beam. Problems with unconnected beam-loss cable rectified. Depth adjusted to get various beam-loss values 50 to 500 mV – see plots. Data taken with beam-line magnets on and counters active. Total ~6000 pulses taken. Finished with calibration run. Target One – 5 th September 3

4 Minimum Distance from Beam Centre Exploring the beam edges Increasing beam loss Calibration run

Studies of beam profile around injection and “bloom” at ~2 ms. Depth & timing scans to optimise beam loss in last 1 ms (≥60%). Studies at increased stator voltages (±125V, ±135V c.f. nominal ±115V) to optimise clearance at next injection. Beam-losses mV delivered for systematic particle vs. beam-loss studies (Adam). Lengthy run at uniform 500 mV for beam-line studies. Another ~6000 pulses taken. Target One – 6 th September 5

6 Calibration run

7 Very preliminary, uncalibrated results from Adam! Arbitrary Units!!

Target performed flawlessly over both days. Total 11,803 actuations over weekend. Target One – 7 th September 8 Access this morning. P Hodgson & D Findlay examined inspection port. D Findlay very happy – “No evidence of any dust”. Will inspect again after further 15K actuations. Permission to run for total 50K in start-up period.

Nominally identical to Target One. Known to have slightly bent shaft – distorted during welding. Assembled in clean room – Sunday 23 rd August. –“By hand”, just as free in bearings as Target 1 Installed in R78 – Tuesday 25 th Electronics commissioned, drive tested – Wednesday 25 th Immediately revealed some odd effects: –Distinctly noisier than first drive –Significantly less reproducible behaviour – see plots Thorough check of electronics & optics Thursday 26 th. –No problem revealed. 9 Target Two – Demonstrator

Returned to clean room, dismantled & inspected Friday 27 th. – Movement had “sticky” feel by hand. –Lower bearing significantly scratched. Transferred to metrology for detailed microscopy & measurement. T2 Min depth 10 Target Two – Continued

Lower bearing Measurement & documentation still in progress. Preliminary conclusions: –Wear on DLC coating of bearings (after <1K actuations!). –No wear on shaft, but pick-up of DLC. –Possibly due to excess pressure due to distorted shaft. 11 Target Two – Continued

Target 2 – Way forward? New shafts and bearings to be produced. New way of fitting stop, to avoid welding distortion. Assemble ~9 th October & re-test. (See Ken’s schedule slide.) Results well before end of October ISIS shutdown. In addition, build “Target 3”. –Same shafts as targets 1 & 2 –Same geometry bearings –New materials/coatings to avoid DLC on DLC problems - Start with Vespel –Schedule indicates assembly by Christmas just possible! 12

Conclusion Target One is running very well on ISIS. The ISIS beam profile has been mapped, and target settings determined for various beam-losses. Particles have been produced reliably for early detector and beam-line commissioning. The target is performing consistently and stably. An operations manual exists, and non-target experts are starting to learn how to use the target controls! Target Two is delayed, but we have a way forward. ISIS have agreed a programme of 50K pulses during the start-up, even without the demonstrator. 13