Difference between revisions of "ASIC design optimizations"
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+ | == Traces of cosmic rays in coincidence with the scintillators == | ||
+ | Here's how the trigger's formed: | ||
+ | {| border="1" cellpadding="2" | ||
+ | |- | ||
+ | |width="415pt"|[[Image:trigger form.jpg|thumb|none|400px|Trigger formation.]] | ||
+ | |- | ||
+ | |} | ||
+ | |||
+ | |||
+ | Here are some infinite persistence traces: | ||
+ | {| border="1" cellpadding="2" | ||
+ | |- | ||
+ | |width="415pt"|[[Image:comics1.jpg|thumb|none|400px|Traces of straight cosmics.]] | ||
+ | |width="415pt"|[[Image:cosmics2.jpg|thumb|none|400px|Traces of straight cosmics.]] | ||
+ | |- | ||
+ | |} | ||
+ | |||
+ | |||
+ | Here are some infinite persistence traces: | ||
+ | {| border="1" cellpadding="2" | ||
+ | |- | ||
+ | |width="415pt"|[[Image:comics1a.jpg|thumb|none|400px|Traces of straight cosmics.]] | ||
+ | |width="415pt"|[[Image:cosmics2a.jpg|thumb|none|400px|Traces of straight cosmics.]] | ||
+ | |width="415pt"|[[Image:cosmics3a.jpg|thumb|none|400px|Traces of straight cosmics.]] | ||
+ | |- | ||
+ | |} | ||
+ | |||
== Fe-55 measurements == | == Fe-55 measurements == | ||
− | Different HV (Straw supported): | + | |
+ | === Cross talk === | ||
+ | |||
+ | To have a quick look concerning cross talk let's show some scatter plots: | ||
+ | |||
+ | {| border="1" cellpadding="2" | ||
+ | |- | ||
+ | |width="415pt"|[[Image:2fe55-begins3.jpg|thumb|none|400px|Fe-55 peak amplitude spectrum (1800 V - begin - upper ).]] | ||
+ | |width="415pt"|[[Image:nextcross.jpg|thumb|none|400px|The straw next to it.]] | ||
+ | |width="415pt"|[[Image:undercross.jpg|thumb|none|400px|The straw underneath it.]] | ||
+ | |- | ||
+ | |} | ||
+ | |||
+ | {| border="1" cellpadding="2" | ||
+ | |- | ||
+ | |width="415pt"|[[Image:elnext.jpg|thumb|none|400px|The electronic channel next to it.]] | ||
+ | |width="415pt"|[[Image:elnext2.jpg|thumb|none|400px|The other electronic channel next to it.]] | ||
+ | |- | ||
+ | |} | ||
+ | |||
+ | There is some electronic cross talk. | ||
+ | |||
+ | === Raw fADC spectra=== | ||
+ | {| border="1" cellpadding="2" | ||
+ | |- | ||
+ | |width="415pt"|[[Image:rawsignal1.jpg|thumb|none|400px|Raw fADC spectrum (1800 V - end - upper ).]] | ||
+ | |width="415pt"|[[Image:rawsignal2.jpg|thumb|none|400px|Raw fADC spectrum (1800 V - end - upper ).]] | ||
+ | |width="415pt"|[[Image:rawsignal3.jpg|thumb|none|400px|Raw fADC spectrum (1800 V - end - upper ).]] | ||
+ | |- | ||
+ | |} | ||
+ | |||
+ | ADC-channel versus time(ns) | ||
+ | |||
+ | Upper means the straw that does not need extra support. | ||
+ | |||
+ | === "Energy" spectra=== | ||
+ | {| border="1" cellpadding="2" | ||
+ | |- | ||
+ | |width="415pt"|[[Image:energy-1750.jpg|thumb|none|400px|"Energy" spectrum (1750 V - begin - upper ).]] | ||
+ | |width="415pt"|[[Image:energy-1800.jpg|thumb|none|400px|"Energy" spectrum (1800 V - begin - upper ).]] | ||
+ | |width="415pt"|[[Image:energy-1850.jpg|thumb|none|400px|"Energy" spectrum (1850 V - begin - upper ).]] | ||
+ | |- | ||
+ | |} | ||
+ | |||
+ | High statistics run: | ||
+ | {| border="1" cellpadding="2" | ||
+ | |- | ||
+ | |width="415pt"|[[Image:energy-1800-hs.jpg|thumb|none|400px|"Energy" spectrum (1800 V - begin - upper ).]] | ||
+ | |- | ||
+ | |} | ||
+ | |||
+ | |||
+ | x-axis is in ADC channels | ||
+ | |||
+ | This measurements correspond with the three measurements with different HV on the straw that does not need extra support. | ||
+ | |||
+ | === Different HV (Straw supported): === | ||
{| border="1" cellpadding="2" | {| border="1" cellpadding="2" | ||
|- | |- | ||
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− | What about measuring another straw (one that | + | What about measuring another straw (one that does not need support - and does not have dead spots): |
Different positions (1800V): | Different positions (1800V): | ||
{| border="1" cellpadding="2" | {| border="1" cellpadding="2" | ||
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Gas: Ar-CO2 87%-13% gas mixture. | Gas: Ar-CO2 87%-13% gas mixture. | ||
Setup: the signal after the shaper was inverted and fed to a discriminator. The HV was changed and the signals above threshold where counted (normalized to 100s measure time). | Setup: the signal after the shaper was inverted and fed to a discriminator. The HV was changed and the signals above threshold where counted (normalized to 100s measure time). | ||
+ | Update: results with 3,4,5 sigma pedestal cuts: | ||
+ | {| border="1" cellpadding="2" | ||
+ | |- | ||
+ | |width="415pt"|[[Image:hvplateau3s.jpg|thumb|none|400px|HV-curve - 3sigma cut, tracked events, normalized to a 40' measurements.]] | ||
+ | |width="415pt"|[[Image:hvplateau4s.jpg|thumb|none|400px|HV-curve - 4sigma cut, tracked events, normalized to a 40' measurement.]] | ||
+ | |width="415pt"|[[Image:hvplateau5s.jpg|thumb|none|400px|HV-curve - 5sigma cut, tracked events, normalized to a 40' measurement.]] | ||
+ | |- | ||
+ | |} | ||
+ | |||
+ | The pedestal means (the error bar is the pedestal width): | ||
+ | {| border="1" cellpadding="2" | ||
+ | |- | ||
+ | |width="415pt"|[[Image:hvplateau-noise.jpg|thumb|none|400px|HV-noise-curve - Pedestal mean as a function of applied HV, the error bars represent the pedestal width]] | ||
+ | |- | ||
+ | |} | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
The result: | The result: | ||
{| border="1" cellpadding="2" | {| border="1" cellpadding="2" |
Latest revision as of 15:24, 7 August 2008
Contents
Traces of cosmic rays in coincidence with the scintillators
Here's how the trigger's formed:
Here are some infinite persistence traces:
Here are some infinite persistence traces:
Fe-55 measurements
Cross talk
To have a quick look concerning cross talk let's show some scatter plots:
There is some electronic cross talk.
Raw fADC spectra
ADC-channel versus time(ns)
Upper means the straw that does not need extra support.
"Energy" spectra
High statistics run:
x-axis is in ADC channels
This measurements correspond with the three measurements with different HV on the straw that does not need extra support.
Different HV (Straw supported):
Different positions (straw supported,1800V):
Different HV (Straw not supported)
Are the measurements reproduce-able?
supported/not supported (middle) + TILTED (55 degrees)
What about measuring another straw (one that does not need support - and does not have dead spots): Different positions (1800V):
Reproduce-able?:
Different-HV:
To finish a high statistics run:
Chamber at 0 degrees
- Measurements with the 55-Fe source
- High Voltage plateau === done
Gas: Ar-CO2 87%-13% gas mixture. Setup: the signal after the shaper was inverted and fed to a discriminator. The HV was changed and the signals above threshold where counted (normalized to 100s measure time). Update: results with 3,4,5 sigma pedestal cuts:
The pedestal means (the error bar is the pedestal width):
The result:
So things start to show up (above threshold, the threshold was set just above noise) at 1500 V and start to break down at +2000V. We see a plateau starting at 1750V. All hv-plateaus are ahown in following figure:
Next the scope traces of the (maximum) noise level after the shaper is shown on the left side. This pickup happens mostly on a different time then a signal. The right side shows a signal at 1800V, also after the shaper. To trigger on the signal I set the threshold to 350 mV.
Let's compare signals at different stages in the electronics chain. Left plot is the signal right BEFORE the pre-amplifier, middle plot is the signal AFTER the pre-amplifier (0.366 times attenuated because of the differential probe), right plot is AFTER the shaper.
- The noise
Noise before preAmp is dominated by the noise pickup of the probe. |
- 1600V
N/A because of noisy probe. |
- 1700V
N/A because of noisy probe. |
- 1750V
- 1800V
- 1900V
- 1950V
- 2000V
What exactly does the shaper? Well you can see this in following traces: from left to right: three signals before/after (green/red) the shaper @ 1800 V:
(remember that the signal before the shaper is attenuated (0.336x) )
The same measurement was performed but now with two probes measuring the differential input signal and MATH function on the scope. Here are three scope traces:
Below galleries of pulses are shown for different HV (on the left channel 2, in the middle channel 15) -- remember everything above 1V is an overflow on the fADC, also the b/w traces are taken with infinite persistence, the colored ones with 10 s persistence. The amplitude spectra are also shown: notice the growing overflow peak around channel 3000 (they are pedestal subtracted):
- 1600 V
- 1650 V
- 1700 V
- 1750 V
- 1800 V
- 1850 V
- 1900 V
- 1950 V
- 2000 V
Chamber at 60 degrees
Below you can find some pulse galleries and amplitude spectra (low statistics)
- 1600 V
- 1650 V
- 1700 V
- 1750 V
- 1800 V
- 1850 V
- 1900 V
- 1950 V
- 2000 V
To Do
- (absolute) Gas gain as a function of High Voltage
Source measurement using Sr-90 (e-) or 55-Fe (X-rays) (if we have it) / or using cosmic rays? -- Estimated time: 1 day -- if we have a good source
- amplitude distributions of tilted chamber
1 week measure with tilted chamber => In progress
- Collection of gallery of pulses
I found 4 pulse galleries, measured directly after the pre-amplifier made by Gerard when he was here, they are shown below: