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 14:08] pereira [Dispersion Matching tuning] |
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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 | ||
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| * 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 | ||
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| - | * Set spectrograph Brho for unreacted fragment | ||
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| - | ==== Start scalers ==== | ||
| - | * Use s800 account | ||
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| - | * 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 | ||
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| - | * 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 | ||
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| * Document optimized transmission with another run to disk to measure rate of fragment of interest at S800 FP | * Document optimized transmission with another run to disk to measure rate of fragment of interest at S800 FP | ||
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| - | === Matched optics === | ||
| - | * Typically much more time is invested for optimizing optics for matched optics than for focused optics | ||
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| - | * One input is optimizing for transmission | ||
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| - | * For tritons a scintillator is required at the pivot position since fragments at 5 Tm will not reach S800 FP | ||
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| - | * The last two analysis line triplets are used to tweak for the desired optical properties | ||
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| - | * Document optimized transmission with another run to disk to measure rate of fragment of interest at S800 FP | ||
| ===== Reaction Setting ===== | ===== 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 | ||
| + | ==== Coincidences ==== | ||
| - | * 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 | ||
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| - | ==== Coincidences ==== | ||
| * Overview | * 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. | * 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. | ||
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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, | ||
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| * 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 | ||
| {{: | {{: | ||
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| + | ====== Reaction Setting ====== | ||
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| + | ===== 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 | ||
tuning_the_s800_xdt.txt · Last modified: 2023/09/22 15:15 by swartzj
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