This shows you the differences between two versions of the page.
Both sides previous revision Previous revision | |||
instruments [2012/12/17 18:17] golack |
instruments [2012/12/17 18:23] (current) golack |
||
---|---|---|---|
Line 12: | Line 12: | ||
Jump position: determine from slow hV scan, pick stable baseline region | Jump position: determine from slow hV scan, pick stable baseline region | ||
Other signs: drift in d47 vs D47 slopes for heated/equilibrated gases | Other signs: drift in d47 vs D47 slopes for heated/equilibrated gases | ||
- | > ''Causes of baseline shifts'' | + | ''Causes of baseline shifts'' |
- | Secondary electrons. Ion beam can kick off electrons when it hits the cups (or walls, other detector components, etc.) This shows up as a negative baseline, especially in the very sensitive cups and wider cups. Scales with main ion beam intensity. | + | Secondary electrons. Ion beam can kick off electrons when it hits the cups (or walls, other detector components, etc.) |
- | Peak tailing. The main ion beam does scatter slightly in flight, and some of those ions can be picked up in other cups, giving rise to a positive baseline. Scales with main ion beam intensity. | + | This shows up as a negative baseline, especially in the very sensitive cups and wider cups. |
- | | + | Scales with main ion beam intensity. |
+ | Peak tailing. The main ion beam does scatter slightly in flight, and some of those ions can be picked up in other cups. | ||
+ | This shows up as a positive baseline. | ||
+ | Scales with main ion beam intensity. | ||
+ | ''to be continued'' | ||