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tuning_the_s800_xdt [2017/06/17 15:06]
pereira [Coincidences]
tuning_the_s800_xdt [2017/07/24 10:48] (current)
pereira
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   * Check **[[s800 SpecTcl|Spectcl]]** window **S800_CRDCS.win** (see figure below) to verify the good performance of the detectors. (The spectra for each CRDC can be checked separatelly in windows **s800_CRDC1.win** and **S800_CRDC2.win**)   * Check **[[s800 SpecTcl|Spectcl]]** window **S800_CRDCS.win** (see figure below) to verify the good performance of the detectors. (The spectra for each CRDC can be checked separatelly in windows **s800_CRDC1.win** and **S800_CRDC2.win**)
  
-      * Spectra **crdc1.raws** and **crdc2.raws** ​(top and middle spectra in the leftmost (first) column) +      * Spectra **crdc1.raws** and **crdc2.raws**  
-          * Each spectra shows the multiple sampled ​signals from each pad +          * Each spectra shows the pad signals ​averaged over the number of samples ​from the SCA (typically four) 
           * The 224 pads are assembled along the dispersive direction           * The 224 pads are assembled along the dispersive direction
           * Width of beam peak is proportional to A1900 p-acceptance in focus optics           * Width of beam peak is proportional to A1900 p-acceptance in focus optics
           * Width is narrower in match optics ​           * Width is narrower in match optics ​
           * Adjust anode HV to bring fuzzy maximum to around 600-700 channels (saturation of each pad at ~ 1000 ch)           * Adjust anode HV to bring fuzzy maximum to around 600-700 channels (saturation of each pad at ~ 1000 ch)
 +          * These are good spectra to check if the pad thresholds are properly set. Thresholds are too low if you see that all pads are firing at low energies. If that's the case, increase the pad thresholds in files **s800crdcv1.tcl** and **s800crdcv2.tcl**,​ under directory **s800/​operations/​daq/​usb/​Configs** (contact device physicist for assistance, if needed).
  
-      * Spectra **crdc1.anode_crdc1.tac** and **crdc2.anode_crdc2.tac** ​(top and middle spectra in the second column)+      * Spectra **crdc1.anode_crdc1.tac** and **crdc2.anode_crdc2.tac** ​
           * This spectrum is used to ensure that the field in the detectors is uniform and well aligned. If the detector is working properly, then the amplitude of the ANODE signals should not depend on the position of the beam (as shown in the figure below) ​           * This spectrum is used to ensure that the field in the detectors is uniform and well aligned. If the detector is working properly, then the amplitude of the ANODE signals should not depend on the position of the beam (as shown in the figure below) ​
           * If the field is not well aligned, then there will be a correlation between ANODE signals and TAC signals ​           * If the field is not well aligned, then there will be a correlation between ANODE signals and TAC signals ​
  
-     * Spectra **crdc1.x_crdc1.padsum** and **crdc2.x_crdc2.padsum** ​(top and middle spectra in the third column)+     * Spectra **crdc1.x_crdc1.padsum** and **crdc2.x_crdc2.padsum** ​
           * It shows the sum over multiple sampled signals from each pad along the (dispersive) x position ​           * It shows the sum over multiple sampled signals from each pad along the (dispersive) x position ​
           * The padsum signals should not show any correlation with the x (dispersive) position ​     ​           * The padsum signals should not show any correlation with the x (dispersive) position ​     ​
  
-      * Spectra **crdc1.xg_crdc1.tac** and **crdc2.xg_crdc2.tac** ​(top and middle spectra in the fourth column)+      * Spectra **crdc1.xg_crdc1.tac** and **crdc2.xg_crdc2.tac** ​
           * It shows the beam distribution in the dispersive (xg) //vs// non-dispersive (tac) directions           * It shows the beam distribution in the dispersive (xg) //vs// non-dispersive (tac) directions
           * It is used to ensure that the fragment beam is centered in the detectors           * It is used to ensure that the fragment beam is centered in the detectors
           * It is also used to see the effect of the beam blocker (used to stop intense contaminants) in the cocktail beam                  * It is also used to see the effect of the beam blocker (used to stop intense contaminants) in the cocktail beam       
   ​   ​
-      * Spectra **crdc1.xg** and **crdc2.xg** ​(bottom spectra in first and second columns)+      * Spectra **crdc1.xg** and **crdc2.xg** ​
           * It shows the position of the beam in the dispersive direction, evaluated by calculating the "​center of gravity"​. The peak should be in the middle of the spectra in order to center the beam           * It shows the position of the beam in the dispersive direction, evaluated by calculating the "​center of gravity"​. The peak should be in the middle of the spectra in order to center the beam
  
- +      ​* Spectra **crdc1.tac** and **crdc2.tac** ​
-      ​* Spectra **crdc1.tac** and **crdc2.tac** ​(bottom spectra in third and fourth columns)+
           * They correspond to the non-dispersive position of the beam in the CRDCs. ​           * They correspond to the non-dispersive position of the beam in the CRDCs. ​
 +
 +      * Spectra **crdc1.pad_mult** and **crdc2.pad_mult** ​
 +          * They show the distribution of pad multiplicies (i.e. number of pads firing for each event). Typical average values are ~10-15. Significantly larger average multiplicities might indicate that the thresholds are set too low.
  
 {{:​wiki:​CRDCS-example.png?​850|S800_CRDCS.win SpecTcl window}} {{:​wiki:​CRDCS-example.png?​850|S800_CRDCS.win SpecTcl window}}
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   * Open the NCS application **QtKM** in the Applications Menu. Open file **BLSetup_A1900.gkm**. The magnetic elements that are typically tweaked with the knob box sitting on the left side of u6pc5 are **I232TA**, **I236TC**, and **I245TC** which can be found on page **S800 BLine+Spectrograph**. Other elements used to improve the focusing in the object point, and the transmission are **I172QA** and **I174QB**. The goal of the dispersion-matching tuning is to find a compromise between transmission and resolution.   * Open the NCS application **QtKM** in the Applications Menu. Open file **BLSetup_A1900.gkm**. The magnetic elements that are typically tweaked with the knob box sitting on the left side of u6pc5 are **I232TA**, **I236TC**, and **I245TC** which can be found on page **S800 BLine+Spectrograph**. Other elements used to improve the focusing in the object point, and the transmission are **I172QA** and **I174QB**. The goal of the dispersion-matching tuning is to find a compromise between transmission and resolution.
        ​{{:​wiki:​QtKM.png?​650|XG.}}        ​{{:​wiki:​QtKM.png?​650|XG.}}
-         * 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. 
 {{:​wiki:​DispMatch-XG-run2.png?​650|XG before tuning.}} {{:​wiki:​DispMatch-XG-run5.png?​650|XG after tuning.}} ​ {{:​wiki:​DispMatch-XG-run2.png?​650|XG before tuning.}} {{:​wiki:​DispMatch-XG-run5.png?​650|XG after tuning.}} ​
  
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   * Setup   * Setup
-      * Coincidence signals are usually visible on scope without running scope in acquire mode+      * Using the [[S800 DAQ tools#​Trigger GUI|trigger GUI]], select (right-click) the wires going into the first AND GATE (see figure below) from the "​S800"​ and "​Secondary"​ (after passing through their respective "Gate & Delay Generators"​) ​  
 +      * Assign each wire to an inspect channel from the patch panel so that you can check their timings ​in the oscilloscope
       * 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)       * 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       * Readjust TDC delays based on changes made to S800 trigger delay
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               * This check is required for verification in cases of low beam intensity (e.g. 1000 pps)               * 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           * Length of run required is typically about 10-15 minutes
-          * To be resolved: ​ whether or not to this run copied from experiment account for documentation of device tuning+
   
  
tuning_the_s800_xdt.1497726388.txt.gz · Last modified: 2017/06/17 15:06 by pereira