Positron emission tomography (PET) is a molecular imaging technique that provides a 3D image of functional processes in the body in vivo. Some of the radionuclides proposed for PET imaging emit high-energy positrons, which travel some distance before they annihilate (positron range), creating significant blurring in the reconstructed images. Their large positron range compromises the achievable spatial resolution of the system, which is more significant when using high-resolution scanners designed for the imaging of small animals. In this work, we trained a deep neural network named Deep-PRC to correct PET images for positron range effects. Deep-PRC was trained with modeled cases using a realistic Monte Carlo simulation tool that considers the positron energy distribution and the materials and tissues it propagates into. Quantification of the reconstructed PET images corrected with Deep-PRC showed that it was able to restore the images by up to 95% without any significant noise increase. The proposed method, which is accessible via Github, can provide an accurate positron range correction in a few seconds for a typical PET acquisition.

X-ray sources with high photon fluxes and small source sizes have been widely pursued in the last decades. With synchrotron and XFEL facilities being complex, scarce and not easily accessible, laser-driven x-ray sources have emerged as a promising option because of their compactness, high photon yield and micrometric source size. In this work, we present the optimisation of an x-ray source driven by means of 0.8 mJ, 35 fs laser pulses focused on a solid Cu target in air. A detailed characterisation of the main x-ray beam parameters is included. A Cu Kα flux of 2.3·10⁹ photons/s has been measured in 2π sr. Despite the simplicity of our setup, this flux is competitive with respect to that achieved with vacuum-based sources. A clear non-isotropic distribution of the x-ray continuum has been recorded, differing from the isotropic emission reported in dedicated studies. The beam is emitted within a cone with a semiangle of ≈14°, directed primarily along the target normal. Given the achieved flux, this source stands as a competitive alternative to more complex laser-driven x-ray sources operating in vacuum or in a He environment.

Laser-driven ion accelerators are a promising alternative to conventional accelerators currently in use. Following the laser-plasma interaction, the target is destroyed, making it necessary to replenish it, a task particularly challenging in the case of state-of-the-art laser systems operating at multi-hertz repetition rates. Here, we will introduce some of the different target systems currently being developed for continuous operation at such rates. In particular, a target system based on a tape-drive that is currently being developed at the Laser Laboratory for Acceleration and Applications (L2A2, USC) will be presented, which addresses the need of a target system capable of operating continuously for thousands of shots at several hertz. Preliminary measurements show tape stabilities below 10 µm of standard deviation.

Highly intense bunches of protons and ions with energies of several MeV/u can be generated with ultra-short laser pulses focused on solid targets. In the most common interaction regime, target normal sheath acceleration, the spectra of these particles are spread over a wide range following a Maxwellian distribution. We report on the design and testing of a magnetic chicane for the selection of protons within a limited energy window. This consisted of two successive, anti-parallel dipole fields generated by cost-effective permanent C-magnets with customized configuration and longitudinal positions. The chicane was implemented into the target vessel of a petawatt laser facility with constraints on the direction of the incoming laser beam and guidance of the outgoing particles through a vacuum port. The separation of protons and carbon ions within distinct energy intervals was demonstrated and compared to a ray tracing code. Measurements with radiochromic film stacks indicated the selection of protons within [2.4, 6.9] MeV, [5.0, 8.4] MeV, or ≥6.9 MeV depending on the lateral dispersion. A narrow peak at 4.8 MeV was observed with a time-of-flight detector.

Laser-plasma interactions of ultra-short laser pulses with solid targets can generate highly intense pulses of protons and ions with energies of several MeV. The spectra of these particles are spread over a wide range following a Maxwellian distribution. We report on the design and testing of a magnetic chicane for the selection of protons within a limited energy window. It consists in two successive, anti-parallel dipole fields generated by cost-effective, permanent C-magnets with customized configuration and longitudinal positions. The chicane has been implemented into the target vessel of a petawatt laser facility under constraints on the direction of the incoming laser beam and guidance of the outgoing particles through a vacuum port. The separation of protons and carbon ions within distinct energy intervals has been demonstrated and compared to a ray tracing code.