Resumen de The next experiment: daq, backgrounds and medical applications
The NEXT collaboration proposes a high pressure xenon TPC to search for neutrinoless double beta decays of Xe-136 at Laboratorio Subterráneo de Canfranc. In this work we present the Data Acquisition system of NEXT-White. To transfer efficiently and store all the relevant information regarding the events detected, a specific-purpose binary format has been defined. A decoding software that translates those binary files to higher-level HDF5 files has been implemented and described in detail. To ensure quality, an automated testing system has been implemented. The performance of the system has been improved by adding the possibility of using a Huffman compression algorithm.
The second part includes an upgrade on the sensitivity studies for the NEXT-100 detector using the latest radiopurity measurements. The study presented in this thesis includes a detailed simulation of the drift, the effect of the electronics and the reconstruction. The results found highlight the critical importance of dealing with the electron cloud diffusion in larger detectors. One solution to the problem is the use of a Richardson-Lucy algorithm that can recover an underlying image blurred by a known Point Spread Function. In the case of NEXT, these PSFs can be produced by analyzing point-like Kr-83m events.
Lastly, the technology developed for the NEXT detectors can also be applied to medical imaging. PETALO is a proposed PET scanner based on liquid xenon (LXe) with SiPM readout. This technology offers several advantages: a very fast scintillation with a high light yield; LXe is a continuous medium with uniform response; and, potentially, identification and reconstruction of Compton events. LXe produces Cherenkov radiation that could be used to achieve a very fast Coincidence Resolving Time in a TOF-PET. A Geant4-based Monte Carlo simulation has been carried out to assess the performance of such a detector. The study presented is a proof-of-concept showing that a CRT of ~30 ps could be achieved with sufficiently fast sensors and electronics.
