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The response of a Timepix3 detector (256 x 256 pixels, pixel pitch 55 μm) with a 300 μm thick silicon sensor was studied in relativistic charged particle beams at the Super-Proton- Synchrotron at CERN. The detector was irradiated at different angles in a 400 GeV/𝑐 primary proton beam and in a mixed beam created by a 330 GeV/𝑐 Pb beam hitting a beryllium target. We present and discuss energy deposition spectra and particle track features for relativistic particles of different stopping power. The proton data shows that a relative energy resolution of approximately 9 % can be achieved. Analysis of deposited energy spectra and tracks in the detector produced by heavier ions are carried out with the aim to investigate the capabilities of the Timepix3 detector for decomposing the mixed beam. Using spectrum stripping technique by iterative Landau curve fitting charge discrimination could be done up to 𝑍 = 7 for impact angle of 60 degrees (with respect to the sensor normal). For smaller impact angles the particle charge separation is decreased due to the saturation of the pixel electronics (600 keV). Previous works describing the 3D track reconstruction for minimally ionizing particles (𝑍 = 1) were extended in the present work by adding the methodology of heavier ions track reconstruction in 3D.

In the framework of the MICADO project we proposed an active long-term nuclear waste monitoring system based on Timepix3 technology. Particle detectors based on Timepix3 are capable of particle type discrimination and provide spectrometric information in combination with precise timing information. To maximize the versatility of the setup, the Timepix3 detectors employed are equipped with a range of different sensors. To enable measurement of neutrons, two quadrants of the detectors are covered by neutron converters, allowing detection of thermal neutron by capture in 6Li, as well as detection of fast neutrons through recoil protons generated in a polyethylene converter. Within this project a new housing for the detector unit and the readout was developed, with the network currently comprising of 9 such detectors. A specifically developed in-house software handles simultaneous operation of all devices, cluster analysis and data visualization. Energy calibration was performed using an X-ray tube with several fluorescence foils as well as photons from an 241Am source. The neutron and gamma/X-ray detection efficiency calibration was carried out at the Czech Metrology Institute and the results are presented here. Tests on simultaneous operation of all 9 devices were performed using uraninite and 241Am sources.

New developments of pixel detectors based on GaAs sensors offer effective registration of the transition radiation (TR) X-rays and perform simultaneous measurements of their energies and emission angles. This unique feature opens new possibilities for particle identification on the basis of maximum available information about generated TR photons. Results of studies of TR energy-angular distributions using a 500 |j.m thick GaAs sensor attached to a Timepix3 chip are presented. Measurements, analysis techniques and a comparison with Monte Carlo (MC) simulations are described and discussed.

Four hybrid pixel detectors of Timepix3 technology, installed in the ATLAS experiment, were continuously taking data from April 2018 until the end of the Run-2 data taking period (December 2019). These detectors are synchronized with each other and the LHC orbit clock. They are capable of resolving the bunch structure of the LHC beams due to their time resolution of ∼ 2 ns . Thus, they allow the characterization of the radiation field inside and outside bunch-crossing periods. This is shown for Timepix3 detectors at the extended barrel (x=-3.58 m, y=0.97 m, z=2.83 m). We apply pattern recognition methods to decompose the radiation field and determine the directionality of the minimum ionizing particles (MIP) component of the radiation field.

We present the results of neutron detection in a laser plasma experiment with a CD$_2$ nanowire target. A hybrid semiconductor pixel detector Timepix3 covered with neutron converters was used for the detection of neutrons. D-D fusion neutrons were detected in a polyethylene converter through recoiled protons. Both the energy of recoiled protons and the time-of-flight of neutrons (and thus their energy) were determined. We report $(2.4 \pm 1.8) \times 10^7$ neutrons generated for 1~J of incoming laser energy. Furthermore, we proved that Timepix3 is suitable for difficult operational conditions in laser experiments., Comment: pdflatex, accepted for publication in NIM A

Growing energies of particles at modern or planned particle accelerator experiments as well as cosmic ray experiments require particle identification at gamma-factors ( γ ) of up to ∼ 105. At present there are no detectors capable of identifying charged particles with reliable efficiency in this range of γ . New developments in high granular pixel detectors allow one to perform simultaneous measurements of the energies and the emission angles of generated transition radiation (TR) X-rays and use the maximum available information to identify particles. First results of studies of TR energy-angular distributions using gallium arsenide (GaAs) sensors bonded to Timepix3 chips are presented. The results are compared with those obtained using a silicon (Si) sensor of the same thickness of 500 μ m. The analysis techniques used for these experiments are discussed.

The performance and response of a Timepix3 detector with a 500 μm thick GaAs:Cr sensor layer was investigated in different radiation fields. The sensor resistivity was ρ 109 Ω cm. Fitting different modified Hecht functions, which take the small pixel effect into account, the mobility-lifetime products of μeτe = (0.773 ± 0.018) × 10-4 cm2V-1 and μeτe = (0.996 ± 0.056) × 10-4 cm2V-1 were determined. Hereby, the latter value is favored due to the better agreement of fit and data. In a measurement in a 40 GeV/c pion beam, the drift times and charge collection efficiencies were studied as a function of the interaction depth. We present the measured drift velocity as a function of the electric field strength and compare the determined dependence with a model. In a measurement in a mixed ion beam, we study the capability of the detector to separate different ion species. We show the detector response in the form of tracks and discuss heavy ion track features. © 2020 IOP Publishing Ltd and Sissa Medialab.

The capability of Timepix3 detectors installed in ATLAS to measure luminosity is evaluated. It is described how noisy pixels are identified and excluded. Two different methods for luminosity determination, i.e. cluster counting and thermal neutron counting are described and compared with each other. The achieved short-term relative precision with both methods is determined by modeling the luminosity curve. It is shown that using cluster counting a short-term relative precision of < 0.5 % can be achieved for 60 s time intervals. For thermal neutrons, a short-term relative precision (for 60 s intervals) of ≈ 2 % was found. Hereby statistics was the limiting factor. The findings are discussed in view of Timepix3 upgrade plans for LHC Run-3.