tuning_the_s800_xdt
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tuning_the_s800_xdt [2023/08/18 17:35] pereira [Send beam to FP] |
tuning_the_s800_xdt [2025/03/07 14:07] (current) swartzj |
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| This page gives the steps that are followed when tuning the S800. The two possible tuning modes are included, namely, the Focus mode and the Dispersion-matching mode. | This page gives the steps that are followed when tuning the S800. The two possible tuning modes are included, namely, the Focus mode and the Dispersion-matching mode. | ||
| - | Before proceeding, it is mandatory to complete all the steps of the [[to-do list|to-do]] list necessary to prepare the S800 for tuning. The preparation of the S800 for tuning is covered by the A1900 prior to every experiment. | + | Before proceeding, it is mandatory to complete all the steps of the [[to-do list|to-do]] list necessary to prepare the S800 for tuning. The preparation of the S800 for tuning is covered by the S800 group prior to every experiment. |
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| ===== 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 A2400) after passing through the S800 target. This is where the term " |
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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 | + | * 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 | + | |
| - | * Using the scope, check the CFD setting: | + | |
| - | * Check CFD walk inspect signal in scope by triggering scope with CFD output | + | * Check [[s800 daq tools# |
| + | * 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) | ||
| + | |||
| + | | ||
| + | * Check CFD walk: inspect 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 | + | * Trigger oscilloscope with CFD output, and check analog |
| - | * With beam on/off, check amplitude of signals | + | * Adjust threshold |
| - | * Raise thresholds to get rid of noise signals. | + | * Check if CFD output displays |
| - | * 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 " | + | * Measure OBJ in scalers and compare it with DB5. Does 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) |
| + | |||
| + | |||
| + | | ||
| + | * 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 " | ||
| + | * 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# | ||
| - | * 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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| * 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 | + | * Different particles with different energy |
| | | ||
| {{: | {{: | ||
| Line 118: | Line 123: | ||
| * **[[hv bias#hv remote control|Bias]]** CRDCs | * **[[hv bias#hv remote control|Bias]]** CRDCs | ||
| * Look at anode signal on **[[electronics overview|scope]]** | * Look at anode signal on **[[electronics overview|scope]]** | ||
| - | * 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 | + | * Check **[[s800 SpecTcl|Spectcl]]** window **S800_CRDCS.win** (see figure below), or, alternatively **S800_MEGASUMMARY.win** |
| * Spectra **crdc1.raws** and **crdc2.raws** | * Spectra **crdc1.raws** and **crdc2.raws** | ||
| - | * Each spectra | + | * Each spectrum |
| * 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 | ||
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| * Make a summing region around the " | * Make a summing region around the " | ||
| * 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 |
| {{: | {{: | ||
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| ====== Dispersion Matching Mode ====== | ====== Dispersion Matching Mode ====== | ||
| - | 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, |
| - | Charge-exchange experiments require typically this optics. In some cases, the beam used is < | + | Charge-exchange experiments require typically this optics. In some cases, the beam used is < |
| * Set trigger to “s800 trigger” | * Set trigger to “s800 trigger” | ||
tuning_the_s800_xdt.1692394553.txt.gz · Last modified: 2023/08/18 17:35 by pereira
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