|Abstract inglese (opzionale):
The main goal is to perform a detailed statistical analysis of the atmospheric background and of the “Abnormal Concentrations” of radioxenon, measured at the Takasaki noble gas station (JPX38) of the International Monitoring System of the CTBTO.
A preliminary descriptive statistical analysis of the empirical distribution was performed and then two types of “Statistical Process Control Charts” were applied to the measured values.
The “Control Chart for Individual Measurements” (Shewhart’s type), sensitive to large variations and the “EWMA Chart”, sensitive to small variations, were applied in order to analyse the overall chronology of the observations and in order to identify and study those values that significantly deviate from the average value.
The application of the Statistical process Control Charts at the JPX38 station shows that this method could contribute, to the periodic monitoring of IMS stations through the use of “Individual Measurements Chart”, supporting the identification of large variations of radio-xenon activity concentrations; while it could be valuable for specific studies on the atmospheric background and on the "anomalies" of radioxenon activity concentrations through the use of the “EWMA Control Chart”.