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tuning_the_s800_xdt [2017/06/17 15:03]
pereira [Coincidences]
tuning_the_s800_xdt [2023/09/22 15:15] (current)
swartzj [CRDCs setup]
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   * Ensure that the S800 spectrograph magnets are tuned to the right rigidity   * Ensure that the S800 spectrograph magnets are tuned to the right rigidity
  
-  * Verify that the beam blocker (labeled I255 Slits) in the S3 page of Barney is open: +  * Verify that the FP beam blocker is fully open:
-      * Expected "open" values for top and bottom slits are CT ~6.8 and CB ~3.2, respectively  +
- +
-  * Ensure that CRAD04 is enabled with a rate limit of **20 kHz** (CRAD04 looks at E1 up FP scintillator)+
  
   * Remember: S800 FP rate limit is **6 kHz**   * Remember: S800 FP rate limit is **6 kHz**
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           * For U-238 (88+) @ ~70 MeV/u: UP (1180 V); DOWN (1280 V)           * For U-238 (88+) @ ~70 MeV/u: UP (1180 V); DOWN (1280 V)
  
-  * Have a good expectation of rate from A1900 group information or from timing scintillators (typically XF_SCI: extended focal-plane detector)+  * Have a good expectation of rate from ARIS group information or from timing scintillators (typically DB5)
  
-  * Remove stops to look for beam at S800 FP with **[[s800 daq tools#scaler display|scalers]]** and adjust beam rate with attenuators+  * Remove stops to look for beam at S800 FP with **[[s800 daq tools#scaler display|scalers]]** 
       * Look at FP scintillator scalers (E1 up, E1 down)       * Look at FP scintillator scalers (E1 up, E1 down)
       * There are typically a few scaler counts without beam       * There are typically a few scaler counts without beam
 +      * If needed, adjust beam rate with operators
 +
  
  
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   * Bias detector. Typical bias: **1200-1800 V** (up to 2200 V)   * Bias detector. Typical bias: **1200-1800 V** (up to 2200 V)
  
-  * Use **[[electronics overview|scope]]** to look at signal patched out to data U6 (channel #54 in data U6 patch panel) +  * Use oscilloscope to look at analog signal patched out to data U4  
-      * This signal is sent to the CANBERRA 454 Quad CFD in data U6 +      * Check rise time and amplitude. Good signal: ~10 ns rise time; 400-500 mV amplitude 
-      * One of the output from this CFD is sent (via patch panel #62) to the TAC and scaler (channel OBJ.Scint) in S3. The other output goes through a passive delayed, and is sent (via patch panel #67) to the Phillips TDC +      * Check if there are reflections (typically seen at ~300 ns after main peak)
-      * Check raising time and amplitude. Good signal: ~10 ns raising time; 400-500 mV amplitude+
    
-  * Using the scope, check the CFD setting+  * Adjust MCFD threshold: 
-      * Check CFD walk inspect signal in scope by triggering scope with CFD output+      * Check [[s800 daq tools#Mesytec CFD gui|Mesytec CFD GUI]] and make sure that configuration file **MCFD16.tcl**  (in directory **/user/s800/s800daq/Configurations**) is used 
 +      * Trigger oscilloscope with MCFD output (see labels in patch panel), and plug analog signal 
 +      * Verify that MCFD delay is ok  
 +      * Adjust MCFD gain based on signal amplitude 
 +      * Adjust threshold to minimize noise 
 +      * Check if MCFD output displays signals triggered by reflections (~300 ns following main peak). If that is the case, increase thresholds or signal width (this is valid only for low-rate experiments) 
 +      * Measure OBJ in scalers and compare it with DB5. Does it make sense? 
 +      * Stop beam and verify background (it should be minimum) 
 + 
 +  * Using the scope, check settings of DU4 CFD (used for TAC)
 +      * Check CFD walkinspect signal in scope by triggering scope with CFD output
       * Ensure that CFD delay cable is ok: about 80% of raising time of the input signal       * Ensure that CFD delay cable is ok: about 80% of raising time of the input signal
-      * Adjust CFD threshold looking at scalers.  +      * Trigger oscilloscope with CFD outputand check analog signals 
-          * With beam on/off, check amplitude of signals from OBJ. You should be able to clearly see the difference between noise signals and fragment-beam signals.  +      * Adjust threshold to minimize noise 
-          Raise thresholds to get rid of noise signals+      * Check if CFD output displays signals triggered by reflections (~300 ns following main peak)If that is the case, increase thresholds or signal width (this is valid only for low-rate experiments) 
-          * NOTE: Be aware that sometimes, after running for a while, the OBJ box is activated. This results in a non-negligible count rate in OBJ scalers with beam off, which comes from HIGH amplitude signals (not noise). DO NOT try to eliminate this "activation" counts by raising the thresholds because that would reduce the efficiency of the detector. +      Measure OBJ in scalers and compare it with DB5Does it make sense? 
-          * The ratio of OBJ to XFP scaler rates (channels OBJ.Scint and XFP.Scint) should reflect the transmission of the cocktail beam (between 60% to 90%, depending on quality of tunning)+      * Stop beam and verify background (it should be minimum) 
 + 
 + 
 +  * NOTE:  
 +      * Be aware that sometimes, after running for a while, the OBJ box is activated. This results in a non-negligible count rate in OBJ scalers with beam off, which comes from HIGH amplitude signals (not noise). DO NOT try to eliminate this "activation" counts by raising the thresholds because that would reduce the efficiency of the detector. Instead, evaluate this activation background rate
 +      * The ratio of OBJ to ARIS (DB5) scaler rates (channels OBJ.Scint and XFP.Scint) should reflect the transmission of the cocktail beam (between 60% to 90%, depending on quality of tunning)
  
-  * Adjust MCFD threshold: 
-      * Using the [[s800 daq tools#Mesytec CFD gui|Mesytec CFD GUI]], open the configuration file **MCFD16.tcl**  in directory **/user/operations/daq/usb/Configs** 
-      * The OBJ signal feeding this module is not patched out to data U6 
-      * The OBJ signal from MCFD module goes to the Mesytec MTDC module and scaler (channel OBJ.MCFD.Scint)  
-      * Make sure that the threshold of the XFP MCFD channel is reasonable. Rates in scaler channels XFP.Scint and XFP.MCFD.Scint should be comparable 
-      * Adjust MCFD OBJ threshold looking at scalers. The ratio of OBJ to XFP scaler rates (channels OBJ.MCFD.Scint and XFP.MCFD.Scint) should reflect the transmission of the cocktail beam         
-      * Save new threshold in configuration file **MCFD16.tcl**  
-    
  
-  * 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 ====
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           * End and Begin **[[s800 daq tools#Run Control Window|ReadoutGUI]]** to assert new trigger condition           * End and Begin **[[s800 daq tools#Run Control Window|ReadoutGUI]]** to assert new trigger condition
  
-  * Select **[[s800 SpecTcl|Spectcl]]** window **S800_SCINT.win** in directory **/user/s800/operations/spectcl/s800v7/Windows**. (NOTE: Spectra definition files can be found in directory **/user/s800/operations/spectcl/s800v7/Definitions**. A good file with useful spectra is **s800xdt.tcl**)+  * Select **[[s800 SpecTcl|Spectcl]]** window **S800_SCINT.win** in directory **/user/s800/s800spectcl/Windows**. (NOTE: Spectra definition files can be found in directory **/user/s800/s800spectcl/Definitions**. A good file with useful spectra is **s800xdt.tcl**)
  
  
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             * Adjust biases so that unreacted beam are at 1/3 to 1/4 of dynamic range             * Adjust biases so that unreacted beam are at 1/3 to 1/4 of dynamic range
             * Reaction product will typically be similar enough to unreacted beam particles             * Reaction product will typically be similar enough to unreacted beam particles
-        * Different particles with different energy loss will shift the curve corresponding to particles covering whole FP+        * Different particles with different energy losses will shift the curve corresponding to particles covering whole FP
                                          
             {{:wiki:E1-updown.png?500|S800 spectra E1 down vs. E1 up.}}             {{:wiki:E1-updown.png?500|S800 spectra E1 down vs. E1 up.}}
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 {{:wiki:IC-raws.png?500|IC.raw spectrum.}} {{:wiki:IC-raws.png?500|IC.raw spectrum.}}
  
-        * Gains are controlled in **s800shpini.tcl** file in directory **s800/operations/daq/usb/Configs** (an example of the content of this file can be seen {{:wiki:s800shpini.pdf|here}}).+        * Gains are controlled in **s800shpini.tcl** file in directory **/user/s800/s800daq/Configurations** (an example of the content of this file can be seen {{:wiki:s800shpini.pdf|here}}).
             * First shaper is for ion chamber             * First shaper is for ion chamber
             * Typically, only coarse gains are used             * Typically, only coarse gains are used
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   * **[[hv bias#hv remote control|Bias]]** CRDCs   * **[[hv bias#hv remote control|Bias]]** CRDCs
       * Look at anode signal on **[[electronics overview|scope]]**  while biasing drift and anode       * Look at anode signal on **[[electronics overview|scope]]**  while biasing drift and anode
-          * Patched to data-U6 on labeled connector+          * Patched to data-U4 on labeled connector
           * **200 – 500 mV** signals are good           * **200 – 500 mV** signals are good
           * CRDC1 anode is noisier (digital noise) than CRDC2            * CRDC1 anode is noisier (digital noise) than CRDC2 
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       * Count rate is a little higher than on scintillator due to noise or thresholds       * Count rate is a little higher than on scintillator due to noise or thresholds
  
-  * 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), or, alternatively **S800_MEGASUMMARY.win** to verify the good performance of the detectors. (The spectra for each CRDC can be checked separately 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 spectrum 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 **/user/s800/s800daq/Configurations** (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 multiplicities (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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          * Make a summing region around the "bananas" in spectra **crdc1.x.tac!ic** and **crdc2.x.tac!ic** (bottom left and right plots respectively)          * Make a summing region around the "bananas" in spectra **crdc1.x.tac!ic** and **crdc2.x.tac!ic** (bottom left and right plots respectively)
          * Stop the run and rescan data from disk          * Stop the run and rescan data from disk
-         * Compare the number of event inside the 2D summing regions with the number of events inside the **ic** gate. Typically the former are very close to the later (nearly 100% efficiency for medium/high Z)+         * Compare the number of event inside the 2D summing regions with the number of events inside the **ic** gate. Typically the former are very close to the latter (nearly 100% efficiency for medium/high Z)
  
 {{:wiki:CRDCS-eff-015028.png?550|S800_CRDCS_EFF.win SpecTcl window}} {{:wiki:CRDCS-eff-015028.png?550|S800_CRDCS_EFF.win SpecTcl window}}
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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), **OBJ-FP** (center), and **XFP-FP** (right). 
-      * 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. Note that in a unreacted-beam setting, the first hit typically provides the "good" ToF (i.e. start and stop signals come from the same event)        * The second row corresponds to the MTDC with all the hits included. Note that in a unreacted-beam setting, the first hit typically provides the "good" ToF (i.e. start and stop signals come from the same event) 
-      * 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). Note that in unreacted-beam setting, the first hit typically provides the "good" ToF (i.e. start and stop signals come from the same event). This is not the case in a reaction setting, where the rates in the XFP and OBJ detectors are much higher than in the FP SCI +      * The two spectra in the fifth row correspond 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). Note that in an unreacted-beam setting, the first hit typically provides the "good" ToF (i.e. start and stop signals come from the same event). This is not the case in a reaction setting, where the rates in the XFP and OBJ detectors are much higher than in the FP SCI 
       * 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 
       * The MTDC delays should never need to be adjusted because the matching window is sufficiently wide (around 4000 ns)       * The MTDC delays should never need to be adjusted because the matching window is sufficiently wide (around 4000 ns)
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       * Measure the beam intensity again and calculate the average value       * 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 for the run number       * 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 for the run number
-      * Check the run time and live time from the corresponding scaler file in directory **/user/s800/converged_daq/scalers**+      * Check the run time and live time from the corresponding scaler file in directory **/user/s800/s800daq/scalers**
       * 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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   * 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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       * The auxiliary detector provides a secondary trigger that is fed into the S800 trigger system       * 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       * 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  [[S800 DAQ tools|trigger GUI]]+      * 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  [[S800 DAQ tools#Trigger GUI|trigger GUI]]
           * A typical S800 delay for SeGA is 450 ns           * A typical S800 delay for SeGA is 450 ns
           * Probably smaller typical S800 delay needed for HiRA           * Probably smaller typical S800 delay needed for HiRA
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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+
   
 +
 +
 +{{:wiki:800px-TriggerGUI.png?800|right|Trigger GUI}}
 +
   * Sample timing for running S800 with SeGA   * Sample timing for running S800 with SeGA
       * SeGA trigger is late with respect to S800 trigger       * SeGA trigger is late with respect to S800 trigger
tuning_the_s800_xdt.1497726201.txt.gz · Last modified: 2017/06/17 15:03 by pereira