Magnetic characterization of ferrite materials used in the ELENA magnetic pick-ups

The CERN Extra Low ENergy Antiproton (ELENA) Ring is a new synchrotron designed for cooling and further decelerating the 5.3 MeV antiprotons delivered by the CERN Antiproton Decelerator (AD). The ring is equipped with two magnetic pick-ups used for longitudinal beam diagnostics. These ultra low noise AC beam transformers consist of a doubly shielded, ferrite-loaded cavity with a ceramic gap in the beam pipe, a secondary winding to which an ultralow noise JFET head amplifier with feedback is connected. The JFET head amplifier is mounted close to the cavity and the AC beam transformers are covering respectively the 0.003-3MHz frequency range (low frequency type) and 0.8-30 MHz frequency range (high frequency type) [1]. The ferrite material used to couple primary and secondary in the beam transformer, has a key impact in the noise characteristics of the amplifier. For this reason a magnetic characterization of the selected ferrite rings has been carried out and is reported in the following.