Evaluation of 3D sensors for fast timing applications.

Novel collider experiments demand an increased performance of the silicon detectors used, such as withstanding up to 1 × 1 0 17 n eq / cm 2 in unprecedented pile-up conditions and providing time resolution around 10 ps. Currently, Low Gain Avalanche Diodes (LGADs) are the standard, achieving resolutions below 30 ps. However, their limited radiation hardness is an area of ongoing research. As an alternative to LGADs, 3D sensors are interesting due to their proven radiation hardness. In 3D sensors, where the columns are etched into the sensor from the top (junction columns) and the back (ohmic columns), the drift distances can be very short, the depletion voltage is low and the electric field can be high, resulting in fast and short signals. In this study, the time resolution of different 3D pixel and strip sensors is investigated with signals generated by electrons as well as an infra-red laser. TCT Timing measurements allow to study the position dependence of the time resolution, which is interesting for 3D sensors due to their complex electric field structure. Position-timing maps prove the direct correlation between time resolution and electric field. The time resolution of 3D sensors before and after irradiation is presented, showing that 3D sensors can reach the time resolution of standard 50 μ m LGADs, which is limited by Landau fluctuations. In addition, the results demonstrate that the radiation-induced performance degradation in 3Ds is less severe than in LGADs. Furthermore, initial results from a production run of dedicated fast 3D sensors which have recently been produced at CNM as a common RD50 project will be presented. Finally, the option of using fast 3D sensors as timing detectors in future collider experiments will be discussed. [ABSTRACT FROM AUTHOR]