Threshold conversions
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The nominal DAC setting is 0x45. | The nominal DAC setting is 0x45. | ||
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Revision as of 14:43, 28 September 2015
The four thresholds – front slow, front fast, rear slow, and rear fast – are controlled by DACs that can be set from 0x00 to 0xFF (i.e., 0 to 255 in decimal). The slow thresholds were calibrated in detail prior to launch, but it is likely that the calibrations have drifted over time.
Contents |
Front slow threshold
Here is a conversion table of selected DAC settings to keV according to the pre-launch calibration. The calibration is a linear function, and the nominal DAC setting is 0x0C.
DAC | 1F | 2F | 3F | 4F | 5F | 6F | 7F | 8F | 9F |
---|---|---|---|---|---|---|---|---|---|
0x0C | 2.68 | 2.66 | 2.58 | 2.82 | 2.61 | 2.51 | 2.32 | 2.63 | 2.52 |
0x10 | 3.49 | 3.44 | 3.32 | 3.59 | 3.40 | 3.26 | 3.09 | 3.42 | 3.25 |
0x20 | 6.68 | 6.55 | 6.27 | 6.66 | 6.57 | 6.27 | 6.15 | 6.58 | 6.19 |
0x40 | 13.1 | 12.8 | 12.2 | 12.8 | 12.9 | 12.3 | 12.3 | 12.9 | 12.1 |
0x80 | 25.9 | 25.3 | 24.0 | 25.1 | 25.6 | 24.3 | 24.5 | 25.6 | 23.8 |
0xFF | 51.2 | 50.0 | 47.4 | 49.5 | 50.7 | 48.1 | 48.8 | 50.7 | 47.1 |
Front fast threshold
The nominal DAC setting is 0x22.
Rear slow threshold
Here is a conversion table of selected DAC settings to keV according to the pre-launch calibration. The calibration is a linear function, and the nominal DAC setting is 0x30.
DAC | 1R | 2R | 3R | 4R | 5R | 6R | 7R | 8R | 9R |
---|---|---|---|---|---|---|---|---|---|
0x30 | 24.1 | 23.4 | 24.0 | 24.3 | 24.5 | 23.9 | 20.8 | 19.0 | 21.1 |
0x40 | 27.3 | 26.4 | 27.2 | 27.6 | 27.5 | 27.1 | 24.6 | 22.5 | 24.1 |
0x80 | 40.0 | 38.5 | 40.1 | 40.5 | 39.7 | 39.8 | 39.9 | 36.6 | 36.0 |
0xFF | 65.1 | 62.6 | 65.5 | 66.3 | 63.9 | 64.9 | 70.4 | 64.5 | 59.6 |
Rear fast threshold
The nominal DAC setting is 0x45.