L. Perktold

The electro-mechanical integration of the NA62 GigaTracker time tagging pixel detector

The NA62 GigaTracker is a low mass time tagging hybrid pixel detector operating in a beam with a particle rate of 750 MHz. It consists of three stations with a sensor size of 60 x 27mm(2) containing 18000 pixels, each 300 x 300 mu m(2). The active area is connected to a matrix of 2 x 5 pixel ASICs, which time tag the arrival of the particles with a binning of 100 ps. The detector operates in vacuum at -20 to 0 degrees C and the material budget per station must be below 0.5% X-0. Due to the high radiation environment of 2 x 10(14) 1 MeV neutron equivalent cm(-2)/yr(-1) it is planned to exchange the detector modules regularly. The low material budget, cooling requirements and the request for easy module access has driven the electro-mechanical integration of the GigaTracker, which is presented in this paper.

Test-beam results of a silicon pixel detector with Time-over-Threshold read-out having ultra-precise time resolution

A time-tagging hybrid silicon pixel detector developed for beam tracking in the NA62 experiment has been tested in a dedicated test-beam at CERN with 10 GeV/c hadrons. Measurements include time resolution, detection efficiency and charge sharing between pixels, as well as effects due to bias voltage variations. A time resolution of less than 150 ps has been measured with a 200 μm thick silicon sensor, using an on-pixel amplifier-discriminator and an end-of-column DLL-based time-to-digital converter.

A 9-Channel, 100 ps LSB Time-to-Digital Converter for the NA62 Gigatracker Readout ASIC (TDCpix)

The TDCpix ASIC is the readout chip for the Gigatracker station of the NA62 experiment. Each station of the Gigatracker needs to provide time stamping of individual particles to 200 ps-rms or better. Bump-bonded to the pixel sensor the ASIC serves an array of 40 columns x 40 pixels. The high precision time measurement of the discriminated hit signals is accomplished with a set of 40 TDCs sitting in the End-Of-Column region of the ASIC. Each TDC provides 9 channels per column. For the time-to-digital converter (TDC) a delay-locked-loop (DLL) approach is employed to achieve a constant time binning of 100ps. Simulation results show that an average rms time resolution of 33ps with a power consumption of the TDC better than 33 mW per column is achieved. This contribution will present the design, simulation results and implementation challenges of the TDC.

Review of results for the NA62 gigatracker read-out prototype

The Gigatracker (GTK) is a hybrid silicon pixel detector developed for NA62, an experiment studying ultra-rare kaon decays at the CERN SPS. The main characteristics are a time-tagging resoluion of 150ps, with low material budget per station (0.5% X0) and a fluence comparable to the one expected for the inner trackers of LHC detectors in 10 years of operation. To compensate the time-walk, two read-out architectures have been designed and produced. The first architecture is based on a Constant Fraction Discriminator (CFD) followed by an on-pixel Time-to-Digital-Converter (TDC). The second architecture is based on a on-pixel group shared TDC. The GTK system developments are described: the integration steps (assembly and cooling) and the results obtained from the prototypes fabricated for the two read-out architectures.

Operational experience with the NA62 Gigatracker

The Gigatracker is a hybrid silicon pixel detector developed for the NA62 experiment at CERN, which aims at measuring the branching fraction of the ultra-rare kaon decay K

The TDCpix ASIC: High rate readout of hybrid pixels with Timing Resolution Better than 200 ps

^{+} \rightarrow \pi^{+} \nu \overline{\nu}

High rate particle tracking and ultra-fast timing with a thin hybrid silicon pixel detector

at the CERN SPS. The detector has to track particles in a 75~GeV/c hadron beam with a flux reaching 1.3~MHz/mm

Characterisation of the NA62 GigaTracker end of column readout ASIC

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The TDCpix readout ASIC: A 75 ps resolution timing front-end for the NA62 Gigatracker hybrid pixel detector

and provide single-hit timing with better than 200 ps r.m.s. resolution for a total material budget of less than 0.5\%~X

Results from the NA62 Gigatracker Prototype: A Low-Mass and sub-ns Time Resolution Silicon Pixel Detector

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