This shows you the differences between two versions of the page.
Both sides previous revision Previous revision Next revision | Previous revision Next revision Both sides next revision | ||
tuning_the_s800_xdt [2015/10/26 14:07] pereira [Setting up Reaction Settings] |
tuning_the_s800_xdt [2015/10/26 14:08] pereira [Reaction Setting] |
||
---|---|---|---|
Line 254: | Line 254: | ||
- | ===== Reaction Setting ===== | + | |
Line 375: | Line 375: | ||
* The two figures below show the spectrum **CRDC1.XG!FOI-AFP-BFP** before (top) and after (bottom) the dispersion-matching tuning for a typical experiment. Be aware that the width given by SpecTcl for the selected peak is not too reliable. It is more convenient to do a real gaussian fit. Unfortunatelly this is not an option included in the current version of SpecTcl. That's why some device physicists prefer SpecTk for this type of tuning | * The two figures below show the spectrum **CRDC1.XG!FOI-AFP-BFP** before (top) and after (bottom) the dispersion-matching tuning for a typical experiment. Be aware that the width given by SpecTcl for the selected peak is not too reliable. It is more convenient to do a real gaussian fit. Unfortunatelly this is not an option included in the current version of SpecTcl. That's why some device physicists prefer SpecTk for this type of tuning | ||
{{: | {{: | ||
+ | |||
+ | |||
+ | ====== Reaction Setting ====== | ||
+ | |||
+ | ===== Setting up Reaction Settings ====== | ||
+ | |||
+ | * Calculating reaction setting | ||
+ | * Center unreacted beam at S800 FP | ||
+ | * Adjust spectrograph Brho to center beam at S800 FP | ||
+ | * Requirements for a beam to be “Centered” | ||
+ | * Spectrograph dipoles matched | ||
+ | * Beam position within about 1 cm of center as judges by 0 point on crdc1x spectrum or on track.xfp spectrum | ||
+ | * Record run to disk to document centered unreacted beam setting | ||
+ | * Calculate reaction setting using “effective” beam energy and the nominal target thickness | ||
+ | * Ideally, experimenters should be the ones making this calculation | ||
+ | * This approach assumes that the target thickness is known | ||
+ | |||
+ | |||
+ | * Reaction setting to FP | ||
+ | * Start with Attenuator setting of unreacted beam and step up in intensity | ||
+ | * Set up beam blocker, if necessary | ||
+ | * Expect to see unreacted beam if reaction setting is within +/- 3% of unreacted beam setting | ||
+ | * Should have to move only one of the two blockers unless charge states are present | ||
+ | * A graphic tool is available to help (not yet calibrated) | ||
+ | * Try to cut only as much as necessary; depends on | ||
+ | * What rate limits allow | ||
+ | * What experimenters want (e.g., if they want singles, the cut has to be more restrictive to limit acquisition deadtime) | ||
+ | * Move blocker, decrease attenuator, repeat | ||