Online charge measurement for petawatt laser-driven ion acceleration

Abstract

Laser-driven ion beams have gained considerable attention for their potential use in multidisciplinary research and technology. Preclinical studies into their radiobiological effectiveness have established the prospect of using laser-driven ion beams for radiotherapy. In particular, research into the beneficial effects of ultrahigh instantaneous dose rates is enabled by the high ion bunch charge and uniquely short bunch lengths present for laser-driven ion beams. Such studies require reliable, online dosimetry methods to monitor the bunch charge for every laser shot to ensure that the prescribed dose is accurately applied to the biological sample. In this paper, we present the first successful use of an Integrating Current Transformer (ICT) for laser-driven ion accelerators. This is a noninvasive diagnostic to measure the charge of the accelerated ion bunch. It enables online estimates of the applied dose in radiobiological experiments and facilitates ion beam tuning, in particular, optimization of the laser ion source, and alignment of the proton transport beamline. We present the ICT implementation and the correlation with other diagnostics, such as radiochromic films, a Thomson parabola spectrometer, and a scintillator.

High power commissioning of BELLA iP2 up to 17 J

“…The targets were mounted to motorized xyz translation stages for rastering. The proton and ion beam properties were measured with a Thomson parabola spectrometer (TPS) equipped with a multi-channel plate coupled to a phosphor screen and CCD for readout, radiochromic film (RCF) stacks that were rotated into the ion beam on-demand at a distance of 5 cm from the target, 2, 10 and an integrating current transformer (ICT, Bergoz ICT-122-070-05:1-VAC) with a collection inner diameter of 12.2 cm, situated at a distance of 60 cm from the target 11,12 and capturing ions within a maximum emission angle of ±6 • . All ion diagnostics were aligned along the target normal (refer to Fig.…”

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

“…As application-readiness is reached for LPA protons, technological developments not only focus on the primary source and according diagnostics but have also diversified to a broad range of dedicated setups for the specific application fields. For radiobiological studies, these developments include dedicated beamlines for protons [5][6][7][8][9] , dosimetric systems [10][11][12][13] and beam monitoring approaches [14][15][16][17] , all contributing to the ability to perform sophisticated experimental studies.…”

Ion-bunch energy acoustic tracing by modulation of the depth-dose curve

“…Other non-invasive detection modalities like e.g. integrating current transformers measure total beam charge without a precise spectrum reconstruction [21] . Due to these issues non-electronic methods like radio chromic films (RCF) or CR39 are still utilized as widespread standard ion diagnostic in laser-ion-acceleration experiments [22,23] .…”

“…On the other hand, when measuring further downstream of the laser–plasma interaction as, for example, done by Thomson parabolas, angular emission features such as energy-dependent cone narrowing are forfeited [ 19 , 20 ] . Other non-invasive detection modalities, such as integrating current transformers, measure the total beam charge without a precise spectrum reconstruction [ 21 ] . Due to these issues, non-electronic methods such as radio chromic films (RCFs) or Columbia Resin #39 (CR39) are still utilized as widespread standard ion diagnostics in laser-ion-acceleration experiments [ 22 , 23 ] .…”