Setup High Resolution Timing

In this page we will detail the processes used to extract high resolution timing from the Pixie-16 modules. Details of how to extract this information can be found in this paper by S. V. Paulauskas. There are other techniques that one can use to optimize the on-board CFD, but they are outside the scope of this guide. We will focus on using the methods implemented in utkscan in the FittingAnalyzer.

#Terminology

• Trace : The entire digitized signal obtained from the Pixie-16 Modules.
• Waveform : The subset of the trace that contains the digitized signal
• Baseline : The section of the trace immediately preceding the waveform.
• Phase : The sub-sampling arrival time of the waveform (the ultimate result of the waveform analysis).
• Sample : A single point in the trace.
• Max(imum) Value : The maximum value of the waveform
• QDC : The baseline-subtracted integrated area of the waveform

#A few tips

• You should ensure that you always have at least 15 samples making up the baseline.

#Obtaining Traces The first thing that one needs to do is obtain some traces to analyze. If you are using the scan software (utkscan, or pixie_ldf_c) you can extract the traces via the TraceExtractor class. Enable this class through the DetectorDriver node in the XML configuration file, and provide it with the type and subtype that it should plot.

#Fitting the Trace Now that you have some traces to fit you can fit them with a trace fitting program. This program is based on ROOT. As is the case in utkscan the waveform range is referenced from the maximum value. For example, a range of [5,10] would give you five samples before the maximum value and ten samples after the maximum. This range is generally sufficient for plastic scintillator signals. The trace can also be accomplished