The New Precise Positioning System of the Heavy Hadron Calorimeter FPSD in the NA61/SHINE Experiment Based on the Siemens 1200 Controller Connected with the EPICS Software

The NA61/SHINE collaboration conducts research using the SPS CERN accelerator, focusing primarily on the strong interaction program. In this type of research, it is necessary to use a hadronic calorimeter called PSD to determine the centrality value of nuclear collisions. The detector consists of two separate parts, the MPSD and the FPSD. The FPSD, which is a new detector added to the NA61 SHINE experiment from 2022, has not yet had a functional system for remotely changing and measuring the detector position. Such a remote system is necessary for faster detector calibration, more precise positioning of the detector in the accelerator beam path, and improved safety. For these reasons, in 2023, a group of specialists from the NCBJ laboratory at Poland, prepared a project and built a remote position change system for the FPSD detector. In this work, we describe the main design assumptions and main features of the finished system. We also describe its control system based on the Siemens 1200 PLC controller and the way we supervise its operation through an external DCS system based on the EPICS software (ver.3.16). The introduced changes improved the safety and comfort of work, reduced the radiation risk, and, above all, significantly shortened the time required to change the position of the FPSD detector.