Pair Spectrometer Low Granularity Calibration
Contents
PSC Calibration
For the better part of the last five years (since appx. 2010) Hall D in conjunction with UNCW has been constructing a Pair Spectrometer (pair-spec). The purpose of which is to convert coherent Bremsstrahlung photons into electron/positron pairs. These charged pairs can be separated and extracted for data about the beam. This is particularly useful data because it is being collected after it has traveled from the tagger magnet, and through the collimator.
In 2013 the counters for the low-granularity section of the pair spectrometer were constructed. In 2014 they were tested, and then installed in Hall D. In fall of 2014, and spring of 2015 test beam was run through the hall as part of a 12 GeV commissioning run. We can take data from the commissioning runs to calibrate the pair-spectrometer to give us data within acceptable accuracy. That is the purpose of this page, to explain, and walk through the calibration process.
PSC Data Recognition and Analysis
Fully calibrating the Pair Spectrometer involves a multitude of data from different sources. The first step is simply accessing the data. Jefferson lab uses a data storage and scientific computing array in CEBAF. It is collectively known as ifarm. Each hall and respective departments store the data from each run on the ifarm server back. When accessing ifarm via secure shell (ssh) we gain access to the repository of data collected.