Some notes on the timing of target changes
A normal target change requires a minimum of 10 shifts. This time may increase if
Numbers 1-9 refer to the table below. |
|
The relation between the end of one run and the start of the next is therefore:
| End of run | Start of next run |
|---|---|
| Monday morning | Thursday afternoon |
| Tuesday morning | Friday afternoon |
| Wednesday morning | Monday afternoon |
| Thursday morning | Tuesday afternoon |
| Friday morning | Tuesday afternoon |
Target changes and radioactive setups on Fridays are best avoided: even small breakdowns have the potential to delay the run by 3 days.
This table contains a more detailed summary of a target change. "Conflict with other separator" generally means that protons must be stopped. If the other separator is taking stable beam then there is no conflict.
| Times required to make a target change | |||||
|---|---|---|---|---|---|
| Action | Allow | Working hours only | Conflict with other separator | Flexible timing? | |
| Radioactive cooling for UC and ThC targets | 72 hr | ||||
| 1 | Cool old target | 2 hr | Y | ||
| 2 | Frontend to atmosphere Ventilation to access mode | 1 hr | Y | Y | |
| 3 | Put new target in zone | 1 hr | Y | Y | Y |
| 4 | Swap targets (robot) | 2 hr | Y | Y | |
| 5 | Pump / heat / outgas target | 40 hr (*) | |||
| 6 | Setup source and separator | 8 hr | Y | (Y if radiation limit in HT room exceeded) | |
| 7 | Proton scan | 2 hr | Y | (parallel operation possible if CA0 not in use) | |
| 8 | Yield check | 5 hr | Y | (parallel operation possible if CA0 not in use) | |
| 9 | User consultation & beam handover | 1 hr | Y | Y | |
(*) Certain targets may require less pumping time. However, starting the HT with a less-than fully outgassed target may cause sparking in the frontend. Excessive sparking is known to damage the frontends. We therefore take a conservative approach, and try to ensure that targets are thoroughly outgassed before they are used.
-TJG
Last update: 7 June 2004