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tuning_the_s800_xdt [2015/10/26 12:41] pereira [Timing setup] |
tuning_the_s800_xdt [2015/10/26 14:08] pereira [Reaction Setting] |
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* Select SpecTcl window **S800_TOF.win** | * Select SpecTcl window **S800_TOF.win** | ||
- | * The three columns correspond to the RF-FP ToF (left), OBJ-FP (center), and XFP-FP (right) | + | * The three columns correspond to the **RF-FP** ToF (left), |
* The first (top) row corresponds to the Phillips TDC | * The first (top) row corresponds to the Phillips TDC | ||
* The second row corresponds to the MTDC with all the hits included | * The second row corresponds to the MTDC with all the hits included | ||
* The third row corresponds to the MTDC with only the first hit | * The third row corresponds to the MTDC with only the first hit | ||
- | * The fourth row corresponds to the ORTEC TACs. Note that there is not RF-FP TAC | + | * The fourth row corresponds to the ORTEC TACs. Note that there is not **RF-FP TAC** |
* The two spectra in the fifth row corresponds to the MTDC summary spectra of OBJ-FP and XFP-FP ToFs (zoomed in). The spectra show the ToF (vertical axis) vs. hit number (horizontal axis). In an unreacted setting, one expects to see the most of the " | * The two spectra in the fifth row corresponds to the MTDC summary spectra of OBJ-FP and XFP-FP ToFs (zoomed in). The spectra show the ToF (vertical axis) vs. hit number (horizontal axis). In an unreacted setting, one expects to see the most of the " | ||
* An empty ToF spectrum means that either the delays are not right (and need to be adjusted) or the spectrum range is too narrow | * An empty ToF spectrum means that either the delays are not right (and need to be adjusted) or the spectrum range is too narrow | ||
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{{: | {{: | ||
- | * Adjust | + | * If necessary, adjust |
- | * | + | * Using the [[S800 DAQ tools# |
- | * | + | * Select the timing signals (Delay inspect channels) E1 up, OBJ and XFP with the [[S800 DAQ tools#Delay Window|Delay GUI]] and look at them in the scope |
- | | + | * Adjust the TDC delays of OBJ and XFP using the delay boxes connected to the CANBERRA CFD 454 in data U6 |
+ | * Adjust the TDC delays of E1 up, down using the Delay GUI | ||
+ | * In principle, the TACs delays don't need to be adjusted | ||
- | | + | ==== Checking Particle ID and rate at S800 FP ==== |
+ | |||
+ | * Select SpecTcl window **S800_PID.win** in directory **/user/s800/ | ||
+ | * The three columns correspond to the PID determined with the **RF-FP** ToF (left), **OBJ-FP** (center), and **XFP-FP** (right) | ||
+ | * The first (top) row corresponds to the Phillips TDC | ||
+ | * The second row corresponds to the MTDC with just the first hit included | ||
+ | * The third row corresponds to the ORTEC TACs. Note that there is not **RF-FP TAC** | ||
+ | * You might need to adjust the limits of the spectra to get a good resolution | ||
+ | |||
+ | {{: | ||
+ | |||
+ | |||
+ | * Establish PID and measure rate | ||
+ | * Determine the blob that corresponds to the unreacted beam (refer to information on setting from A1900 FP) | ||
+ | * Take gates around the fragment of interest | ||
+ | * Measure the beam intensity the appropriate faraday cup | ||
+ | * Take a run on disk | ||
+ | * Measure the beam intensity again and calculate the average value | ||
+ | * In [[s800 SpecTcl|SpecTcl GUI]], click **Attach to File** and select data file **run-xxxx-xx.evt** in directory **/user/s800/stagearea/experiment/runxxxx**, where xxxx stands | ||
+ | * 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 | ||
- | * The TDC delays can only be changed when the run control is stopped; must SAVE settings before starting run control not to overwrite adjustments being made | ||
- | * The “S800” trigger is from E1 up signal | ||
- | * Trigger the scope with the “Live Trigger” signal patched to data-U6 | ||
- | * There are 4 trigger inspect channels patched to data-U6 that can be assigned using the trigger GUI | ||
- | * Examine the timing of each of the selectable listed signals with respect to the “Live Trigger” signal | ||
- | * There are 4 TDC inspect channels patched to data-U6 that can be assigned using the trigger GUI | ||
- | * The full range of the TDC is 400 ns | ||
- | * Set each timing to 200 ns | ||
- | * TDCs of last 4 listed signals (including XF and object scintillators) are bypassed with cable delays inside the vault and thus their delays cannot be controlled with the GUI | ||
- | * They can be inspected, however using the GUI | ||
- | * Information | ||
- | * The signal delays controlled by the GUI (and not by cable delays) are not “pipelined” -– i.e., any new signals that arrive during the delay time of a previous signal are lost and thus deadtime is introduced into the system. | ||
- | * All of the trigger signals are not pipelined and are thus subject to deadtime | ||
- | ==== Checking Particle ID and rate at S800 FP ==== | ||
- | * Establish PID | ||
- | * Refer to information on setting from A1900 FP | ||
- | * dE-TOF | ||
- | * dE signal from Ion Chamber | ||
- | * TOF from XF or Object scintillator to S800 FP | ||
- | * Not necessary to implement dE- or TOF-based corrections | ||
- | * Document rate of fragment of interest with run to disk | ||
- | * Measure beam current with appropriate Faraday cups | ||
- | * Timed run | ||
==== Analysis line classic PPAC setup (Focus optics only) ==== | ==== Analysis line classic PPAC setup (Focus optics only) ==== | ||
+ | |||
* " | * " | ||
* 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. | ||
- | |||
- | |||
- | ==== 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 === | ||
+ | |||
* 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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- | === 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 | + | ==== Coincidences |
- | + | ||
- | * Document optimized transmission with another run to disk to measure rate of fragment of interest at S800 FP | + | |
- | + | ||
- | + | ||
- | ===== 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 | * 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 ====== | ||
+ | |||
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 | ||
{{: | {{: | ||
+ | |||
+ | |||
+ | ====== 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 | ||