Speaker
Description
Low Gain Avalanche Diodes (LGADs) are silicon detectors with an intrinsic gain, developed for timing measurements in High Energy Physics Experiments. The sate-of-the-art LGADs foreseen for ATLAS and CMS experiments feature a channel size of about 2 mm$^2$ on 50 $\mu$m thick silicon providing a timing resolution of about 30 ps for Minimum Ionizing Particles (MIPs). These detectors are radiation hard up to a fluence of few 10$^{15}$ n$\rm_{eq}$/cm$^2$.
Thanks to these properties, LGADs are a promising technology to build a Time-of-Flight system for future space missions to improve the tracking capabilities of the instruments.
In fact, due to the compact design of the payloads, secondary particles created in the calorimeter may enter the tracker, degrading the performance of the latter in reconstructing the trajectory of the observed primary particle. Adding a time tag to each event in the tracker would reduce this effect.
In the past few years, LGAD technology has been developed by Fondazione Bruno Kessler with the channel size of 1 cm$^2$, which is the typical one of the silicon micro-strip sensors for trackers in numerous space experiments.
Wafers with thicknesses 50 , 100, and 150 $\mu$m, and different gain layers were produced to study the effect of capacitance and gain on the timing performance of the sensor. Each wafer contains pad sensors with three different active areas and different metallization.
The timing performance of these devices is evaluated using Transient Current Technique and a $^{90}$Sr radioactive source. Jitter of about 80 ps is measured for the 1 cm$^2$ LGADs with a gain of about 40. However, a non uniform gain was also observed in the sensors, worsening the timing resolution even with the laser.
A timing resolution of about 150 ps is measured with the beta particles. The performance of these sensors is limited by the gain as increasing the bias further would put them into breakdown. A new batch of sensors were produced to improve the gain and timing resolution of the detectors.
In addition to that, uniformity and propagation of the signal will be investigated by comprehensively studying the layout variations present in the batch.
The simulations performed to design the batch, the electrical characterization along with the gain measurements, and the first results of timing resolution for the new batch of large area LGADs will be presented in this work.
| Eligibility for "Best presentation for young researcher" or "Best poster for young researcher" prize | Yes |
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