Resolutions
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Contents
Prelude
- Two gases are used: 70/30 and 90/10 Ar/CO2
- Two fADC clock settings are used: 125 and 200 MHz
- Drift time spectra (DCOG method is used):
- Red line is fit to get absolute minimal drift time
- Best tracking results if extracted minimal drift time + 1 time sample
- Samples per rising edge - 2 extra samples 125 -> 200 MHz
- Time-2-distance relation:
- GARFIELD is used. To get best resolutions out of it:
- 68/32 Ar/CO2 is put in GARFIELD for 70/30 gas
- 89/11 Ar/CO2 is put in GARFIELD for 90/10 gas
- +-6% CO2 can give 100~ns difference
- GARFIELD is used. To get best resolutions out of it:
Resolutions
- Difference in gases - blue line is a model prediction:
- 90/10 worse because shorter drift times.
- Model contains:
- Timing resolution (0.75 length of time sample)
- accuracy
- diffusion (Garfield)
- Table with resolutions for straw 7 and different clock settings:
- high: with hit removed from tracking
- low: with hit included
Distance from wire [mm] | Resolution (low) [um] | Resolution (high [um] | ||
---|---|---|---|---|
125 MHz | 200 MHz | 125 MHz | 200 MHz | |
0-1 | 388 | 394 | 404 | 396 |
1-2 | 346 | 292 | 346 | 205 |
2-3 | 209 | 191 | 222 | 210 |
3-4 | 142 | 135 | 166 | 165 |
4-5 | 118 | 96 | 164 | 151 |
5-6 | 85 | 88 | 148 | 164 |
6-7 | 67 | 70 | 165 | 174 |
7-8 | 65 | 63 | 158 | 169 |
- The difference between high and low is largest for 1-3 mm driftdistances but overall the difference is not that big.
- Gas mixture has a big impact
- We might not have a big enough lever arm:
GARFIELD - DATA
Below 70/30 gas mixture ch 7: left MC, right data
To do
- There is a full simulation of the chamber and results are on there way
- We are testing 80/20 gas right now
- We want to test the same gas mixture as FDC uses
- We also want to try and add ethane
- Try different timing algorithms
- Find a way to extract the timing resolution directly