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tuning_the_s800_xdt [2017/06/17 15:04] pereira [Coincidences] |
tuning_the_s800_xdt [2023/08/18 17:49] pereira [Object scintillator 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 | + | * Verify that the FP beam blocker is fully open: |
- | * Expected " | + | |
- | + | ||
- | * 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 | + | * Have a good expectation of rate from ARIS group information or from timing scintillators (typically |
- | * Remove stops to look for beam at S800 FP with **[[s800 daq tools# | + | * Remove stops to look for beam at S800 FP with **[[s800 daq tools# |
* 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]]** | + | * Use oscilloscope |
- | * This signal is sent to the CANBERRA 454 Quad CFD in data U6 | + | |
- | * 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 raising time and amplitude. Good signal: ~10 ns raising time; 400-500 mV amplitude | * Check raising time and amplitude. Good signal: ~10 ns raising time; 400-500 mV amplitude | ||
+ | * Check if there are reflections (typically seen at ~300 ns after main peak) | ||
* Using the scope, check the CFD setting: | * Using the scope, check the CFD setting: | ||
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* Adjust MCFD threshold: | * Adjust MCFD threshold: | ||
- | * Using the [[s800 daq tools# | + | * Using the [[s800 daq tools# |
* 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 module goes to the Mesytec MTDC module and scaler (channel OBJ.MCFD.Scint) | * The OBJ signal from MCFD module goes to the Mesytec MTDC module and scaler (channel OBJ.MCFD.Scint) | ||
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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 **/ | + | * Select **[[s800 SpecTcl|Spectcl]]** window **S800_SCINT.win** in directory **/ |
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{{: | {{: | ||
- | * 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 {{: | + | * Gains are controlled in **s800shpini.tcl** file in directory **/user/s800/s800daq/Configurations** (an example of the content of this file can be seen {{: |
* 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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* 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** | + | * Spectra **crdc1.raws** and **crdc2.raws** |
- | * Each spectra shows the multiple sampled | + | * Each spectra shows the pad signals |
* 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**, | ||
- | * Spectra **crdc1.anode_crdc1.tac** and **crdc2.anode_crdc2.tac** | + | * 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** | + | * 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** | + | * 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** | + | * Spectra **crdc1.xg** and **crdc2.xg** |
* It shows the position of the beam in the dispersive direction, evaluated by calculating the " | * It shows the position of the beam in the dispersive direction, evaluated by calculating the " | ||
- | + | | |
- | | + | |
* 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. | ||
{{: | {{: | ||
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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 " | * 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 " | ||
- | * 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 | + | * The two spectra in the fifth row correspond |
* 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 **/ | * 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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* 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. | ||
| | ||
- | * 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. |
{{: | {{: | ||
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* Setup | * Setup | ||
- | * Coincidence signals are usually visible on scope without running scope in acquire mode | + | * Using the [[S800 DAQ tools# |
+ | * Assign each wire to an inspect channel from the patch panel so that you can check their timings | ||
* 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: | + | |
+ | |||
+ | |||
+ | {{: | ||
+ | |||
* 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 |