The PETRA III 40 electron bunches, 192 ns apart, were solved using the TEMPUS detector. The time resolution achieved in that experiment was limited by the sensor to 11 and 23 ns for photons of 6.4 and 14.4 keV respectively.
TEMPUS is a pixel detector based on the Timepix4 chip [1] from the Medipix4 collaboration, with two operating modes: a photon counting mode with frame readout, offering a high frame rate and count rate; and an "event readout" mode, where the position, timestamp and energy of each incoming photon are recorded. This has a variety of applications, particularly at PETRA-III.
TEMPUS is being developed as a successor to LAMBDA [2]. Initially, a single-chip system is being developed, with 512 x 448 pixels and 55 µm pixel size. It offers 10 times higher count rate than LAMBDA in the photon-counting mode and up to 40 kHz frame rate, as well as 200ps time resolution in the event-driven mode.
The Timepix4 chip is also designed to take full advantage of the through silicion via (TSV) technology. This means in future versions of the system we will be able to fully remove the wirebond connections on the sides, decreasing the dead areas when placing several chips together.
When running at full speed, the detector will produce a data rate of over 80 Gb/s, and dealing with this large amount of data is one of the main challenges ahead.
In experiments at the PETRA-III synchrotron, the ability to switch between frame mode and event mode will make TEMPUS a versatile system. First results obtained at PETRA III show the capabilities of the system, for example in enabling XPCS experiments on sub-microsecond timescales, and time resolution at the single bunch level or better in experiments such as NRS.
[1] X. Llopart, et al. (2022), JINST 17, C01044. [2] D. Pennicard et al. (2011), JINST 6, C11009.
