LHC magnet quench detection by trend analysis of the pressure signal

CERN's LHC is composed of thousands of superconductor magnets that may sometimes quench (lose suddenly their superconducting properties). This paper presents a method to detect magnet quenches from the pressure of the helium inside the magnets. The method detects slight deflexions on the pressure signal created by a magnet quench. The deflexion is recognized through a trend analysis of the pressure filtered first derivative, where a specific shape formed of two consecutives temporal episodes signs the presence of a quench. The method was tested on a database composed of 30 pressure signals, where a total of 94 quenches occurred during the measurements. The results were analysed through a ROC curve and showed that the method was able to detect 84% of the quenches with only one false alarm.