tuning_the_s800_xdt
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tuning_the_s800_xdt [2015/10/21 16:09] pereira |
tuning_the_s800_xdt [2015/10/26 14:07] pereira [Setting up Reaction Settings] |
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| ====== Focus Mode ====== | ====== Focus Mode ====== | ||
| For most of the experiments in the S800, the analysis line is run in focus mode. In this optics, the analysis line is achromatic, i.e. the dispersive position of the beam focused in the target area (pivot point) does not depend on the momentum. Thus, this mode provides the biggest momentum acceptance (4%). On the other hand, since the spectrograph focal plane is chromatic, the resolution is limited to about 1 part in 1000 in energy. | For most of the experiments in the S800, the analysis line is run in focus mode. In this optics, the analysis line is achromatic, i.e. the dispersive position of the beam focused in the target area (pivot point) does not depend on the momentum. Thus, this mode provides the biggest momentum acceptance (4%). On the other hand, since the spectrograph focal plane is chromatic, the resolution is limited to about 1 part in 1000 in energy. | ||
| + | |||
| ===== Unreacted beam ===== | ===== Unreacted beam ===== | ||
| In the first part of the XDT, the rigidity of the S800 is typically set to match the value of the fragment beam (selected in the A1900) after passing through the S800 target. This is where the term " | In the first part of the XDT, the rigidity of the S800 is typically set to match the value of the fragment beam (selected in the A1900) after passing through the S800 target. This is where the term " | ||
| - | === Send beam to FP === | + | ==== Send beam to FP ==== |
| * Ensure that the S800 spectrograph magnets are tuned to the right rigidity | * Ensure that the S800 spectrograph magnets are tuned to the right rigidity | ||
| Line 39: | Line 40: | ||
| - | === Object scintillator setup === | + | ==== Object scintillator setup ==== |
| * Bias detector. Typical bias: **1200-1800 V** (up to 2200 V) | * Bias detector. Typical bias: **1200-1800 V** (up to 2200 V) | ||
| Line 57: | Line 58: | ||
| * The OBJ signal feeding this module is not patched out to data U6 | * The OBJ signal feeding this module is not patched out to data U6 | ||
| * The OBJ signal from MCFD-16 module goes to the Mesytec MTDC32 module and scaler (channel OBJ.MCFD.Scint) | * The OBJ signal from MCFD-16 module goes to the Mesytec MTDC32 module and scaler (channel OBJ.MCFD.Scint) | ||
| - | * Adjust | + | |
| + | | ||
| * Save new threshold in configuration file **MCFD16.tcl** | * Save new threshold in configuration file **MCFD16.tcl** | ||
| Line 63: | Line 65: | ||
| * Watch for no rate change on scaler display with a bias adjustment up or down of about 50-100 V | * Watch for no rate change on scaler display with a bias adjustment up or down of about 50-100 V | ||
| - | === FP scintillator setup === | + | ==== FP scintillator setup ==== |
| * Set trigger to “s800 trigger” | * Set trigger to “s800 trigger” | ||
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| - | === Ionization Chamber setup === | + | ==== Ionization Chamber setup ==== |
| * Gas should be [[Gas handling system# | * Gas should be [[Gas handling system# | ||
| Line 106: | Line 108: | ||
| - | === CRDCs setup === | + | ==== CRDCs setup ==== |
| * **[[hv bias#hv remote control|Bias]]** CRDCs | * **[[hv bias#hv remote control|Bias]]** CRDCs | ||
| Line 156: | Line 158: | ||
| - | === Timing setup === | + | ==== Timing setup ==== |
| + | At present, there are three electronic " | ||
| - | * See [[http:// | ||
| - | * The TDC delays can only be changed when the run control | + | |
| + | | ||
| + | * The first (top) row corresponds to the Phillips | ||
| + | * 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 fourth row corresponds to the ORTEC TACs. Note that there is not **RF-FP TAC** | ||
| + | * The two spectra in the fifth row corresponds | ||
| + | * An empty ToF spectrum means that either the delays are not right (and need to be adjusted) or the spectrum range is too narrow | ||
| + | * The MTDC spectra should never be empty because the matching window is sufficiently wide (around 4000 ns) | ||
| - | * The “S800” trigger is from E1 up signal | + | {{: |
| - | * Trigger the scope with the “Live Trigger” signal patched to data-U6 | + | * If necessary, adjust delays: |
| - | * There are 4 trigger | + | * Using the [[S800 DAQ tools#Trigger |
| + | * Select the timing signals (Delay | ||
| + | * Adjust the TDC delays of OBJ and XFP using the delay boxes connected | ||
| + | * Adjust the TDC delays of E1 up, down using the Delay GUI | ||
| + | * In principle, the TACs delays don't need to be adjusted | ||
| - | * 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 | + | ==== Checking Particle ID and rate at S800 FP ==== |
| - | * 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 === | + | * Select SpecTcl window **S800_PID.win** in directory **/ |
| - | | + | * The three columns correspond |
| - | * Refer to information on setting from A1900 FP | + | * The first (top) row corresponds |
| - | | + | * The second row corresponds to the MTDC with just the first hit included |
| - | * dE signal from Ion Chamber | + | * The third row corresponds to the ORTEC TACs. Note that there is not **RF-FP TAC** |
| - | * TOF from XF or Object scintillator to S800 FP | + | * You might need to adjust the limits of the spectra to get a good resolution |
| - | | + | |
| - | * Document rate of fragment of interest | + | |
| - | * Measure beam current with appropriate Faraday cups | + | |
| - | * Timed run | + | |
| + | {{: | ||
| - | === Analysis line classic PPAC setup (Focus optics only) === | + | * 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 **/ | ||
| + | * 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 | ||
| + | |||
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| + | ==== Analysis line classic PPAC setup (Focus optics only) ==== | ||
| * " | * " | ||
| * Classic PPACs have rate limitations from pileups | * Classic PPACs have rate limitations from pileups | ||
| Line 213: | Line 236: | ||
| + | ==== Setting Optimization ==== | ||
| - | === Setup beamline | + | === Focused optics |
| - | * 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 === | ||
| - | |||
| - | === 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 | ||
| Line 249: | Line 252: | ||
| * 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 | ||
| - | |||
| - | |||
| - | === 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 | ||
| ===== 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 | ||
| - | |||
| - | ==== 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. | ||
| Line 375: | Line 344: | ||
| ====== 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, | ||
tuning_the_s800_xdt.txt · Last modified: 2023/09/22 15:15 by swartzj
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