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Abstract-The renewal of interest in Time of Flight PositronEmission Tomography (TOF-PET), as well as the necessity to precisely tag events in high energy physics (HEP) experiments at future colliders are pushing for an optimization of all factors affecting the time resolution of the whole acquisition chain comprising the crystal, the photo detector, and the electronics. The time resolution of a scintillator-based detection system is determined by the rate of photo electrons at the detection threshold, which depends on the time distribution of photons being converted in the photo detector. The possibility to achieve time resolution of about 100 ps Full Width at Half Maximum (FWHM) requires an optimization of the light production in the scintillator, the light transport and its transfer from the scintillator to the photo detector. In order to maximize the light yield, and in particular the density of photons in the first nanosecond, while minimizing the rise time and decay time, particular attention must be paid to the energy transfer mechanisms to the activator as well as to the energy transition type at the activator ion. Alternatively other light emission mechanisms can be considered. We show that particularly Cerenkov emission can be used for this purpose. Special emphasis was put on the light transport within the crystal and at its interface with the photo detector. Since light is produced isotropically in the scintillator the detector geometry must be optimized to decrease the optical path-length to the photo detector. Moreover light bouncing within the scintillator, affecting about 70% of the photons generated in currently used crystals, must be reduced as much as possible. We also investigate photonics crystals that are specifically designed to favor specific light propagation modes at the limit of total reflection inside and outside of the crystal and how they might increase the light transfer efficiency to the photo detector and hence improve time resolution. Examples for the production and deposition of photonics crystals as layers on Lutetium Yttrium Ortho-Silicate (LYSO) and Lutetium Yttrium Aluminum Perovskite (LuYAP) crystals are shown here, as well as first results on an improved light extraction resulting from this method.

The development from single shot basic laser plasma interaction research toward experiments in which repetition rated laser-driven ion sources can be applied requires technological improvements. For example, in the case of radio-biological experiments, irradiation duration and reproducible controlled conditions are important for performing studies with a large number of samples. We present important technological advancements of recent years at the ATLAS 300 laser in Garching near Munich since our last radiation biology experiment. Improvements range from target positioning over proton transport and diagnostics to specimen handling. Exemplarily, we show the current capabilities by performing an application oriented experiment employing the zebrafish embryo model as a living vertebrate organism for laser-driven proton irradiation. The size, intensity, and energy of the laser-driven proton bunches resulted in evaluable partial body changes in the small (<1 mm) embryos, confirming the feasibility of the experimental system. The outcomes of this first study show both the appropriateness of the current capabilities and the required improvements of our laser-driven proton source for in vivo biological experiments, in particular the need for accurate, spatially resolved single bunch dosimetry and image guidance.

The aim of this review was to define appropriate 11 B delivery agents for boron proton-capture enhanced proton therapy (BPCEPT) taking into account the accumulated knowledge on boron compounds used for boron neutron capture therapy (BNCT). BPCEPT is a promising treatment approach which uses a high linear energy transfer (LET) dose component in conjunction with conventional proton therapy to increase the relative biological effectiveness of highly-selective charged particle therapy. Boron proton fusion reactions occur with highest cross section at certain proton energy level and thus can be tailored to the target volume with careful treatment planning that defines the 675 MeV proton distribution with high accuracy. Appropriate 11 B compounds are required in order to achieve relevant high LET dose contribution from the boron proton-capture reaction. Previous scientific results and experiences with BNCT provide background knowledge and information regarding the optimization of boronated compound development, their characterization, measurement and imaging. However, there are substantial differences between BNCT and BPCEPT, which in turn places special unique chemical, physical and biological demands on 11 B-carrier compounds for BPCEPT. In this review, we evaluate well-known and recently developed boron compounds for BPCEPT.

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