Difference between revisions of "CDC prototype more drift times"
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Drift time histograms for various local pedestal points | Drift time histograms for various local pedestal points | ||
<br> | <br> | ||
− | The pedestal | + | The local pedestal is taken to be the mean of a number of samples (pedestal window) ending a certain number of samples (pedestal lead time) before the bin where the hit crossing threshold is exceeded. Typically for a hit threshold of 5x pedestal sigma, a window of 1 or 2 samples ending at a lead time of 3 or 4 samples works well. For a window of 1 sample and lead time of 3 samples, the pedestal value is taken to be equal to the fADC value 3 samples before the hit threshold is exceeded. |
Also see [[CDC_prototype_more_on_timing]] | Also see [[CDC_prototype_more_on_timing]] | ||
<br> | <br> | ||
− | Le_bin is the timing threshold crossing in fADC samples (8ns each) and it is relative to the hit threshold crossing time. | + | Le_bin is the timing threshold crossing in fADC samples (8ns each) and it is relative to the hit threshold crossing time.<br> |
− | Le_bin=0 corresponds to (15 + pedestal lead) samples before the hit threshold crossing bin. | + | Le_bin=0 corresponds to (15 + pedestal lead) samples before the hit threshold crossing bin.<br> |
+ | Le_bin=15 corresponds to pedestal_lead samples before the hit threshold crossing, this is where the pedestal window ends.<br> | ||
ie the drift time in bins is hit threshold crossing bin - 15 - pedestal_lead_time + le_bin. | ie the drift time in bins is hit threshold crossing bin - 15 - pedestal_lead_time + le_bin. | ||
The sample values sent to the upsampling algorithm start at le_bin=0. 20 + pedestal_lead_time values are used so the upsampling data end 5 samples after the hit threshold crossing bin. | The sample values sent to the upsampling algorithm start at le_bin=0. 20 + pedestal_lead_time values are used so the upsampling data end 5 samples after the hit threshold crossing bin. |
Revision as of 12:47, 8 March 2012
Drift time histograms for various local pedestal points
The local pedestal is taken to be the mean of a number of samples (pedestal window) ending a certain number of samples (pedestal lead time) before the bin where the hit crossing threshold is exceeded. Typically for a hit threshold of 5x pedestal sigma, a window of 1 or 2 samples ending at a lead time of 3 or 4 samples works well. For a window of 1 sample and lead time of 3 samples, the pedestal value is taken to be equal to the fADC value 3 samples before the hit threshold is exceeded.
Also see CDC_prototype_more_on_timing
Le_bin is the timing threshold crossing in fADC samples (8ns each) and it is relative to the hit threshold crossing time.
Le_bin=0 corresponds to (15 + pedestal lead) samples before the hit threshold crossing bin.
Le_bin=15 corresponds to pedestal_lead samples before the hit threshold crossing, this is where the pedestal window ends.
ie the drift time in bins is hit threshold crossing bin - 15 - pedestal_lead_time + le_bin.
The sample values sent to the upsampling algorithm start at le_bin=0. 20 + pedestal_lead_time values are used so the upsampling data end 5 samples after the hit threshold crossing bin.
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