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tuning_the_s800_xdt [2023/08/18 17:35] pereira [Send beam to FP] |
tuning_the_s800_xdt [2023/09/22 14:48] swartzj [FP scintillator setup] |
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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 |
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{{: | {{: | ||
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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** |
* 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 |