N. Spencer

Functional characteristics and radiation tolerance of AToM, the front-end chip of BaBar silicon vertex tracker

The readout chip designed to process the microstrip signals in the BaBar silicon vertex tracker (SVT), after being realized twice in a radsoft technology has been transferred into the final radhard process. So far the circuit has gone through four different radhard submissions, one aiming at providing a preliminary insight into the characteristics of the radhard chip, the other ones constituting pre-production and production runs. Chips from these submissions have undergone a thorough set of tests addressing functional aspects, noise parameters and effects of radiation on signal and noise behavior. The present paper discusses the results of these tests and describes the final version of the circuit which has been proven to successfully meet the experiment requirements.

The BaBaR drift chamber project

The BaBar Drift Chamber is now under construction. We review its design, the progress in the construction of the components, the plan for assembly and stringing and we present test results obtained with a prototype exposed at SLAC to cosmic rays. We also report on projected dE/dx performance from beam tests done with a chamber with a different cell design.

Ultra-Fast Silicon Detectors for 4D tracking

We review the progress toward the development of a novel type of silicon detectors suited for tracking with a picosecond timing resolution, the so called Ultra-Fast Silicon Detectors. The goal is to create a new family of particle detectors merging excellent position and timing resolution with GHz counting capabilities, very low material budget, radiation resistance, fine granularity, low power, insensitivity to magnetic field, and affordability. We aim to achieve concurrent precisions of ~ 10 ps and ~ 10 μm with a 50 μm thick sensor. Ultra-Fast Silicon Detectors are based on the concept of Low-Gain Avalanche Detectors, which are silicon detectors with an internal multiplication mechanism so that they generate a signal which is factor ~ 10 larger than standard silicon detectors.

Temperature dependence of the response of ultra fast silicon detectors

The Ultra Fast Silicon Detectors (UFSD) are a novel concept of silicon detectors based on the Low Gain Avalanche Diode (LGAD) technology, which are able to obtain time resolution of the order of few tens of picoseconds. First prototypes with different geometries (pads/pixels/strips), thickness (300 and 50 μm) and gain (between 5 and 20) have been recently designed and manufactured by CNM (Centro Nacional de Microelectronica, Barcelona) and FBK (Fondazione Bruno Kessler, Trento). Several measurements on these devices have been performed in laboratory and in beam test and a dependence of the gain on the temperature has been observed. Some of the first measurements will be shown (leakage current, breakdown voltage, gain and time resolution on the 300 μm from FBK and gain on the 50 μm-thick sensor from CNM) and a comparison with the theoretically predicted trend will be discussed.

The 4D pixel challenge

Is it possible to design a detector able to concurrently measure time and position with high precision? This question is at the root of the research and development of silicon sensors presented in this contribution. Silicon sensors are the most common type of particle detectors used for charged particle tracking, however their rather poor time resolution limits their use as precise timing detectors. A few years ago we have picked up the gantlet of enhancing the remarkable position resolution of silicon sensors with precise timing capability. I will be presenting our results in the following pages.

The BaBar drift chamber project

The BaBar Drift Chamber is now under construction. We review its design, the progress in the construction of the components, the plan for assembly and stringing and we present test results obtained with a prototype exposed at SLAC to cosmic rays. We also report on projected dE/dx performance from beam tests done with a chamber with a different cell design.