Performance evaluation of a point of load for the upgrade of the ATLAS - LAr calorimeter

The paper deals with the magnetic field (often denoted also as B-field) behavior of Point of Load devices developed in order to meet the requirement in term of magnetic field and radiation hardness mandatory for experiments operating at LHC. Devices have been tested under magnetic field up to about 1.2 T at the Laboratorio Acceleratori e Superconduttività Applicata (LASA), a laboratory located in Milan (Italy). The obtained experimental results are here presented in detail and, finally, discussed. The device here used has been designed to meet the stringent specification given for experiments at LHC taking also into account the planned upgrade for the denoted High Luminosity LHC (HL-LHC). The ability to operate in the hostile environment of the device presented in this paper (a DC-DC converter) is very interesting especially when the device is used in measurement systems: such as the Liquid Argon Calorimeter (LAr) of the ATLAS experiment at CERN. In this case, in fact, the simultaneous presence of radiation and strong static magnetic fields impose particularly harsh working conditions to semiconductor devices, for the presence of radiation, and to the coils, for the presence of magnetic field. In this paper, the experimental results obtained during the tests planned to verify the capability to work in hostile environment of a particular device designed by a research group at CERN has been presented. Details on trend of the output voltage, ripple, efficiency of the device are given and discussed.