miniSCIDOM: a scintillator-based tomograph for volumetric dose reconstruction of single laser-driven proton bunches

Laser plasma accelerators(LPAs)enable the generation of intense and short proton bunches on a micrometre scale,thus offering new experimental capabilities to research fields such as ultra-high dose rate radiobiology or material analysis.Being spectrally broadband,laser-accelerated proton bunches allow for tailored volumetric dose deposition in a sample via single bunches to excite or probe specific sample properties.The rising number of such experiments indicates a need for diagnostics providing spatially resolved characterization of dose distributions with volumes of approximately 1 cm^(3) for single proton bunches to allow for fast online feedback.Here we present the scintillator-based miniSCIDOM detector for online single-bunch tomographic reconstruction of dose distributions in volumes of up to approximately 1 cm^(3).The detector achieves a spatial resolution below 500μm and a sensitivity of 100 mGy.The detector performance is tested at a proton therapy cyclotron and an LPA proton source.The experiments’primary focus is the characterization of the scintillator’s ionization quenching behaviour.

Three-dimensional acoustic monitoring of laser-accelerated protons in the focus of a pulsed-power solenoid lens

The acoustic pulse emitted from the Bragg peak of a laser-accelerated proton bunch focused into water has recently enabled the reconstruction of the bunch energy distribution.By adding three ultrasonic transducers and implementing a fast data analysis of the filtered raw signals,I-BEAT(Ion-Bunch Energy Acoustic Tracing)3D now provides the mean bunch energy and absolute lateral bunch position in real-time and for individual bunches.Relative changes in energy spread and lateral bunch size can also be monitored.Our experiments at DRACO with proton bunch energies between 10 and 30 MeV reveal sub-MeV and sub-mm resolution.In addition to this 3D bunch information,the signal strength correlates also with the absolute bunch particle number.

OCTOPOD:single-bunch tomography for angular-spectral characterization of laser-driven protons

Laser-plasma accelerated(LPA)proton bunches are now applied for research fields ranging from ultra-high-dose-rate radiobiology to material science.Yet,the capabilities to characterize the spectrally and angularly broad LPA bunches lag behind the rapidly evolving applications.The OCTOPOD translates the angularly resolved spectral characterization of LPA proton bunches into the spatially resolved detection of the volumetric dose distribution deposited in a liquid scintillator.Up to 24 multi-pinhole arrays record projections of the scintillation light distribution and allow for tomographic reconstruction of the volumetric dose deposition pattern,from which proton spectra may be retrieved.Applying the OCTOPOD at a cyclotron,we show the reliable retrieval of various spatial dose deposition patterns and detector sensitivity over a broad dose range.Moreover,the OCTOPOD was installed at an LPA proton source,providing real-time data on proton acceleration performance and attesting the system optimal performance in the harsh laser-plasma environment.

Performance demonstration of the PENELOPE main amplifier HEPA I using broadband nanosecond pulses

We report on the energetic and beam quality performance of the second to the last main amplifier section HEPA I of the PENELOPE laser project. A polarization coupled double-12-pass scheme to verify the full amplification capacity of the last two amplifiers HEPA I and II was used. The small signal gain for a narrow-band continuous wave laser was 900 and 527 for a broadband nanosecond pulse, demonstrating 12.6 J of output pulse energy. Those pulses, being spectrally wide enough to support equivalent 150 fs long ultrashort pulses, are shown with an excellent spatial beam quality. A first active correction of the wavefront using a deformable mirror resulted in a Strehl ratio of 76% in the single-12-pass configuration for HEPA I.

Targets for high repetition rate laser facilities:needs,challenges and perspectives

A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target needs for three different classes of experiments: dynamic compression physics, electron transport and isochoric heating, and laser-driven particle and radiation sources. We also review some of the most challenging issues in target fabrication and high repetition rate operation. Finally, we discuss current target supply strategies and future perspectives to establish a sustainable target provision infrastructure for advanced laser facilities.

ReLaX:the Helmholtz International Beamline for Extreme Fields high-intensity short-pulse laser driver for relativistic laser-matter interaction and strong-field science using the high energy density instrument at the European X-ray free electron laser fac

High-energy and high-intensity lasers are essential for pushing the boundaries of science.Their development has allowed leaps forward in basic research areas,including laser±plasma interaction,high-energy density science,metrology,biology and medical technology.The Helmholtz International Beamline for Extreme Fields user consortium contributes and operates two high-peak-power optical lasers using the high energy density instrument at the European X-ray free electron laser(EuXFEL)facility.These lasers will be used to generate transient extreme states of density and temperature to be probed by the X-ray beam.This paper introduces the ReLaX laser,a short-pulse high-intensity Ti:Sa laser system,and discusses its characteristics as available for user experiments.It will also present the first experimental commissioning results validating its successful integration into the EuXFEL infrastructure and viability as a relativisticintensity laser driver.