tuning_the_s800_xdt
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tuning_the_s800_xdt [2015/10/26 13:56] pereira [Checking Particle ID and rate at S800 FP] |
tuning_the_s800_xdt [2015/10/26 14:09] pereira [Setting up Reaction Settings] |
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| * Adjust the TDC delays of E1 up, down using the Delay GUI | * Adjust the TDC delays of E1 up, down using the Delay GUI | ||
| * In principle, the TACs delays don't need to be adjusted | * In principle, the TACs delays don't need to be adjusted | ||
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| ==== Checking Particle ID and rate at S800 FP ==== | ==== Checking Particle ID and rate at S800 FP ==== | ||
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| * Take a run on disk | * Take a run on disk | ||
| * Measure the beam intensity again and calculate the average value | * Measure the beam intensity again and calculate the average value | ||
| - | * In SpecTcl GUI, click **Attach to File** and select data file **run-xxxx-xx.evt** in directory **/ | + | * In [[s800 SpecTcl|SpecTcl GUI]], click **Attach to File** and select data file **run-xxxx-xx.evt** in directory **/ |
| * Check the run time and live time from the corresponding scaler file in directory **/ | * Check the run time and live time from the corresponding scaler file in directory **/ | ||
| * Calculate the rate and purity and compare with the value in the A1900 FP to determine the transmission | * Calculate the rate and purity and compare with the value in the A1900 FP to determine the transmission | ||
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| ==== Analysis line classic PPAC setup (Focus optics only) ==== | ==== Analysis line classic PPAC setup (Focus optics only) ==== | ||
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| * " | * " | ||
| * Classic PPACs have rate limitations from pileups | * Classic PPACs have rate limitations from pileups | ||
| Line 223: | Line 235: | ||
| * Confirm correlations between dispersive angle at intermediate image and p in FP (e.g., crdc1x). This correlation will be somewhat washed out by straggling in the target; in principle, this should be checked without the target, but the benefit vs. cost in time to remove the target is not worth it. | * Confirm correlations between dispersive angle at intermediate image and p in FP (e.g., crdc1x). This correlation will be somewhat washed out by straggling in the target; in principle, this should be checked without the target, but the benefit vs. cost in time to remove the target is not worth it. | ||
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| - | ==== Setup beamline ==== | ||
| - | * Object and XF scintillators and intermediate image PPACs inserted if they will be used | ||
| - | * If Object scintillator will not be used, there is no reason to look at beam on it unless to debug a problem with the transmission | ||
| - | |||
| - | * Set spectrograph Brho for unreacted fragment | ||
| - | |||
| - | ==== Start scalers ==== | ||
| - | * Use s800 account | ||
| - | |||
| - | * Make sure experiment daq is: | ||
| - | * Stopped | ||
| - | * Gone | ||
| - | * Open terminal window (from bottom of mac) | ||
| - | * ssh to spdaq20 | ||
| - | * ps auw | grep Readout | ||
| - | * Does not get restarted | ||
| - | |||
| - | * Under operations folder on mac | ||
| - | * scalers (gives error if no bridge) | ||
| ==== Setting Optimization ==== | ==== Setting Optimization ==== | ||
| === Focused optics === | === Focused optics === | ||
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| * Expectations for A1900 FP to S800 FP transmission | * Expectations for A1900 FP to S800 FP transmission | ||
| * 80% or better for mid-Z fragments | * 80% or better for mid-Z fragments | ||
| Line 262: | Line 254: | ||
| - | === Matched optics === | ||
| - | * Typically much more time is invested for optimizing optics for matched optics than for focused optics | ||
| - | * One input is optimizing for transmission | ||
| - | |||
| - | * For tritons a scintillator is required at the pivot position since fragments at 5 Tm will not reach S800 FP | ||
| - | |||
| - | * The last two analysis line triplets are used to tweak for the desired optical properties | ||
| - | |||
| - | * Document optimized transmission with another run to disk to measure rate of fragment of interest at S800 FP | ||
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| - | ===== 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 | ||
| - | |||
| - | ==== Coincidences ==== | ||
| - | * 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” | ||
| - | |||
| - | * 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: | ||
| - | |||
| - | * 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: | ||
| - | |||
| - | * 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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| - | * 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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| ====== Dispersion Matching tuning ====== | ====== Dispersion Matching tuning ====== | ||
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| In the dispersion-matching optics, the S800 focal point is achromatic, i.e. the position of the beam in the dispersive direction does not depend on the momentum. As a consequence, | In the dispersion-matching optics, the S800 focal point is achromatic, i.e. the position of the beam in the dispersive direction does not depend on the momentum. As a consequence, | ||
| Line 416: | Line 332: | ||
| * 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 | ||
| + | |||
| + | |||
| + | |||
| + | |||
| + | |||
| + | ===== Coincidences ===== | ||
| + | |||
| + | * 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” | ||
| + | |||
| + | * 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: | ||
| + | |||
| + | * 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: | ||
| + | |||
| + | * 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:// | ||
| + | |||
| + | {{: | ||
| + | |||
| + | * 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 | ||
| + | |||
| + | {{: | ||
| + | |||
tuning_the_s800_xdt.txt · Last modified: 2023/09/22 15:15 by swartzj
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