arXiv subjects

T. Bischoff

Publications and source records attributed to T. Bischoff.

3 recordsLinked to original sources

arXiv2026

Testbeam characterization of a 3D silicon sensor read out by Timepix4

Testbeam results from a $300\,\mu\mathrm{m}$-thick 3D silicon sensor bump-bonded to a Timepix4 ASIC, are presented. The hit detection efficiency, spatial resolution, and timing performance of the 3D sensor are studied for several track angles, bias voltages and charge thresholds. The time measurements are corrected for Timepix4 clock-frequency variations and timewalk, while for the spatial studies, nonlinear charge-sharing corrections are determined. At perpendicular incidence, the time resolution of the 3D detector is equal to $245\,\mathrm{ps}$ with a $97\%$ hit detection efficiency. An optimal angle of $8^\circ$ with respect to the beam direction of the 3D detector was found, in which the time resolution improves by $6\%$ compared to normal incidence, while the hit detection efficiency reaches above $99\%$ and the spatial resolution is approximately $7\,\mu\mathrm{m}$. Intrapixel studies show that a time resolution of $153\,\mathrm{ps}$ at the most probable value of the signal charge can be achieved for hits between the electrodes at normal incidence, while the timing performance of these best-performing regions deteriorate upon sensor rotation. The timing properties at different depths of the 3D sensor have been investigated with tracks at grazing-angle incidence, revealing a dependence of the time resolution along the sensor depth.

physics.ins-det↗

arXiv2023

Double diffraction imaging of X-ray induced structural dynamics in single free nanoparticles

Because of their high photon flux, X-ray free-electron lasers (FEL) allow to resolve the structure of individual nanoparticles via coherent diffractive imaging (CDI) within a single X-ray pulse. Since the inevitable rapid destruction of the sample limits the achievable resolution, a thorough understanding of the spatiotemporal evolution of matter on the nanoscale following the irradiation is crucial. We present a technique to track X-ray induced structural changes in time and space by recording two consecutive diffraction patterns of the same single, free-flying nanoparticle, acquired separately on two large-area detectors opposite to each other, thus examining both the initial and evolved particle structure. We demonstrate the method at the extreme ultraviolet (XUV) and soft X-ray Free-electron LASer in Hamburg (FLASH), investigating xenon clusters as model systems. By splitting a single XUV pulse, two diffraction patterns from the same particle can be obtained. For focus intensities of about $2\cdot10^{12}\,\text{W/cm}^2$ we observe still largely intact clusters even at the longest delays of up to 650 picoseconds of the second pulse, indicating that in the highly absorbing systems the damage remains confined to one side of the cluster. Instead, in case of five times higher flux, the diffraction patterns show clear signatures of disintegration, namely increased diameters and density fluctuations in the fragmenting clusters. Future improvements to the accessible range of dynamics and time resolution of the approach are discussed.

physics.atm-clus↗

arXiv2022

Charge and temporal characterisation of silicon sensors using a two-photon absorption laser

First measurements are presented from a newly commissioned two-photon absorption (TPA) setup at Nikhef. The characterisation of the various components of the system is discussed. Two planar silicon sensors, one being electron collecting and one hole collecting, are characterised with detailed measurements of the charge collection and time resolution. The TPA spot is determined to have a radius of 0.975(11) $μ\text{m}$ and length of 23.8 $μ\text{m}$ in silicon. The trigger time resolution of the system is shown to be maximally 30.4 ps. For both sensors, uniform charge collection is observed over the pixels, and the pixel side metallisation is imaged directly using the TPA technique. The best time resolution for a single pixel is found to be 600 ps and 560 ps for the electron and hole collecting sensors respectively, and is dominated by ASIC contributions. Further scans at different depths in the sensor and positions within the pixels have been performed and show a uniform response. It is concluded that the TPA setup is a powerful tool to investigate the charge collection and temporal properties of silicon sensors.

physics.ins-det↗