Speaker
Description
The Timepix4 provides time of arrival (ToA) and time over threshold (ToT) information on detected events, which is used to improve its imaging capabilities. We present an evaluation of the correction of the ‘timewalk’ effect of a Timepix4.2 pixel detector ASIC, bump-bonded to a 300 um planar silicon sensor, performing time-of-flight-based particle identification, spatial resolution measurements for TEM, and lab-based laser and test-pulse measurements. We show a comparison between the three different methods – using test-pulse data, photon data, and charged-particle data, and discuss the scope of the application of each.
A timewalk correction is applied in two separate campaigns involving the Timepix4:
Charged-particle data was obtained at the PSI PiM1 beam line using coincidence with a MALTA-based beam telescope. The positron beam was used to study the fractional radiation length of ATLAS, CMS, and Mu3e detector modules. The time of flight of scattered particles was measured by the Timepix4 with respect to a beam clock, thus separating in time the positron component of the beam from muon and pion contamination. After applying a timewalk correction based on test-pulses and the charged beam data, the FWHM of the positron peak decreases from ~ 4 ns to ~ 3 ns. Further, performing ToT-charge calibration decreases the peak width down to ~ 2ns, limited by the trigger system of the telescope.
Measurements of the Timepix4 imaging resolution were performed with a TEM at the Rosalind Franklin Institute. The Modulation Transfer Function (MTF) of the detector was evaluated for 100 keV and 200 keV electrons. After applying a timewalk correction based on photon data taken with an IR laser, and calibrating the ToT values per-pixel, offline geometric and temporal hit clustering is performed. The MTF at Nyquist frequency is improved by factors of ~ 2 and ~ 3 for low- and high-energy electrons respectively.
| Workshop topics | Applications |
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