tuning_the_s800_xdt
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tuning_the_s800_xdt [2015/10/26 14:09] pereira [Coincidences] |
tuning_the_s800_xdt [2015/10/26 14:09] pereira [Follow-up] |
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| - | ===== Follow-up ===== | ||
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| - | * Before leaving beam with experimenters | ||
| - | * Set up current trip points on Linux HV controls | ||
| - | * Values used for K-48 | ||
| - | * 5 for CRDC and Ion Chamber anodes and intermediate image ppacs | ||
| - | * 50 for CRDC drifts | ||
| - | * 80 for IC drift | ||
| - | * Ensure alarms are running | ||
| - | * Make sure Linux HV GUI alarms are enabled | ||
| - | * Make sure threshold on isobutane level is set up (not currently connected to alarms because they give too many false alarms when communication is lost) | ||
| - | * All logs are being recorded | ||
| - | * There is no log file for biases controlled by Labview | ||
| - | * Linux HV | ||
| - | * LabView gas handling system | ||
| - | * Note in logbook | ||
| - | * Scintillator biases | ||
| - | * IC gate biases | ||
| - | * Post reference printouts for experimenters | ||
| - | * HV status: a snapshot of HV GUI | ||
| - | * Gas handling system status: a snapshot of LabView window | ||
| - | |||
| - | * Create window configuration with summing regions to make it easier for experimenters to track efficiency/ | ||
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| - | * Setting up coincidences for additional reaction settings in an experiment | ||
| - | * Do not need to redo coincidence settup if secondary beam does not change | ||
| - | * Might need to redo coincidence setup if secondary beam changes drastically | ||
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| - | * To watch during experiment | ||
| - | * Look for isobutene running out – messes up data over several hours | ||
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| - | * Implementing dE- or TOF-based corrections is part of EXR | ||
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| - | More detail needed | ||
| - | Minimum rates required for coincidence setup | ||
| - | Selection of appropriate substitute reactions for coincidence setup | ||
| - | How to feel comfortable that there will not be a problem with FP detector gases running out | ||
| - | Starting alarms | ||
| - | Starting logging | ||
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| * What experimenters want (e.g., if they want singles, the cut has to be more restrictive to limit acquisition deadtime) | * 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 | * Move blocker, decrease attenuator, repeat | ||
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| + | ===== Coincidences ===== | ||
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| + | * Overview | ||
| + | * Most experiments at the S800 involve setting up an auxiliary detector system (e.g. SeGA, HiRA, etc) to be used in coincidence with the standard detectors of the S800. | ||
| + | * The auxiliary detector provides a secondary trigger that is fed into the S800 trigger system | ||
| + | * A key part of setting up the S800 for such experiments is getting proper timing setup between the S800 and any auxiliary detectors | ||
| + | * For cases where the Secondary detector has a slow response relative to the S800, the coincidence timing must be reset to the S800 timing by delaying the S800 trigger using the third gate and delay generator on the trigger GUI | ||
| + | * A typical S800 delay for SeGA is 450 ns | ||
| + | * Probably smaller typical S800 delay needed for HiRA | ||
| + | * An example of experiments where auxiliary detectors are not used and, thus, setting up coincidence timing is not an issue are the experiments with tritons run by the charge exchange group | ||
| + | * It is not clear whether coincidence setup gets logged as “XDT” or “EXR” | ||
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| + | * Choice of setting to be used for coincidence timing setup | ||
| + | * The reaction of interest for the experiment can be used to setup coincidences only if the rate of coincidences is high enough | ||
| + | * Sometime the pilot beam is used for setting up the coincidence timing in cases where the intensity of the secondary beam is too small | ||
| + | * Example: | ||
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| + | * Setup | ||
| + | * Coincidence signals are usually visible on scope without running scope in acquire mode | ||
| + | * Adjust the width of the early signal (S800 or secondary) should be wide enough to catch coincidences with the late signal (width of late signal is not critical) | ||
| + | * Readjust TDC delays based on changes made to S800 trigger delay | ||
| + | * Experimenters will need to adjust their delays based on delay made to S800 trigger | ||
| + | * Have experimenters record a run with coincidences on their account | ||
| + | * S800 trigger TDC channel should show a peak (which corresponds to coincidences) | ||
| + | * " | ||
| + | * This check is required for verification in cases of low beam intensity (e.g. 1000 pps) | ||
| + | * Length of run required is typically about 10-15 minutes | ||
| + | * To be resolved: | ||
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| + | * Sample timing for running S800 with SeGA | ||
| + | * SeGA trigger is late with respect to S800 trigger | ||
| + | * The figure below represents a timing schematic to show how to | ||
| + | * Setup of the S800 trigger to recover timing needed for proper functioning of S800 FP detectors | ||
| + | * Set up the coincidence trigger | ||
| + | * See: http:// | ||
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| + | {{: | ||
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| + | * A double peak structure will appear in the TDC for the S800 trigger between the coincidence events and the singles events (see figure below); the groups are separated by 25 ns because of the delay introduced by the downscaler used for the singles | ||
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| + | {{: | ||
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tuning_the_s800_xdt.txt · Last modified: 2023/09/22 15:15 by swartzj
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