Münster 2017 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 94: Pixeldetektoren 4

T 94.2: Vortrag

Mittwoch, 29. März 2017, 17:00–17:15, VSH 116

Charge calibration for the read-out chip of the ATLAS Insertable B-Layer — Joern Grosse-Knetter, Arnulf Quadt, and •Paolo Sabatini — II. Physikalisches Institut, Georg-August-Universität Göttingen

The Insertable B-Layer (IBL) is the innermost layer of the ATLAS Pixel detector, composed of 14 staves located around the beam pipe at a distance of about 33 mm, hosting about 12 million hybrid-silicon pixels. A new generation of Front End chips (FE-I4) was developed exclusively for this component, in order to sustain the challenging hit rate and radiation dose. The insertion of this layer improves the performance on secondary vertex recognition (b-tagging) maintaining the total material budget of the detector low.

Being the innermost layer requires a high position resolution, which is improved by algorithms exploiting the measured charge in each pixel of the cluster induced by a crossing particle. This information is obtained, for each pixel, by measuring the Time-over-Threshold (ToT) of the measured signal, expected to be proportional to the deposited charge. That makes the ToT-to-charge calibration important for track position reconstruction and it requires an automatic test and tuning procedure, aimed to ensure the correct charge measurement for each pixel of the detector. This calibration, performed via on-chip charge injection, depends on two conversion factors known to limited precision from wafer probing. New improved calibration ideas based on production and operation data will be presented.