  This master thesis presents a new type of Positron Emission TOF Apparatus
using Liquid xenOn (PETALO). The detector is based in the Liquid Xenon
Scintillating Cell (LXSC). The cell is a box filled with liquid xenon (LXe)
whose transverse dimensions are chosen to optimize packing and with a thickness
optimized to contain a large fraction of the incoming photons. The entry and
exit faces of the box (relative to the incoming gammas direction) are
instrumented with large silicon photomultipliers (SiPMs), coated with a
wavelength shifter, tetraphenyl butadiene (TPB). The non-instrumented faces are
covered by reflecting Teflon coated with TPB. In this thesis we show that the
LXSC can display an energy resolution of 5% FWHM, much better than that of
conventional solid scintillators such as LSO/LYSO. The LXSC can measure the
interaction point of the incoming photon with a resolution in the three
coordinates of 1 mm. The very fast scintillation time of LXe (2 ns) and the
availability of suitable sensors and electronics permits a coincidence
resolution time (CRT) in the range of 100-200 ps, again much better than any
current PET-TOF system. The LXSC constitutes the core of a high-sensitivity,
nuclear magnetic resonance compatible, PET device, with enhanced Time Of Flight
(TOF) sensitivity.
