Kelby Anderson

The OPAL silicon-tungsten calorimeter front end electronics

A pair of small angle silicon-tungsten (Si-W) calorimeters has been built to measure the luminosity to a precision better than 0.1% in the OPAL experiment at the Large Electron Positron (LEP) collider at CERN near Geneva. Each calorimeter contains 19 layers of tungsten (W) plates and silicon (Si) detectors, corresponding to a total of 22 radiation lengths, sampled by about 1 m/sup 2/ of detectors divided into 304/spl times/64 independently read out channels. A complete electronics system has been developed, from the preamplifier up to the VME read out and control interface. It includes a fast trigger based on analogue sums. This paper describes how a large number of channels have been implemented in a dense environment, thanks to the use of ASICs directly bonded on the detector. >

Search for lepton-flavour-violating decays of the Higgs and Z bosons with the ATLAS detector

Direct searches for lepton flavour violation in decays of the Higgs and Z bosons with the ATLAS detector at the LHC are presented. The following three decays are considered: H → eτ , H → μτ , and Z → μτ . The searches are based on the data sample of proton–proton collisions collected by the ATLAS detector corresponding to an integrated luminosity of 20.3 fb−1 at a centre-of-mass energy of √ s = 8 TeV. No significant excess is observed, and upper limits on the lepton-flavour-violating branching ratios are set at the 95% confidence level: Br(H → eτ) < 1.04%, Br(H → μτ) < 1.43%, and Br(Z → μτ) < 1.69 × 10−5.

The ATLAS tile calorimeter digitizer

We describe a readout system designed to serve the 9728 PMT channels of the ATLAS Tile calorimeter at LHC. The system will be located immediately outside the calorimeter with limited accessibility and moderate radiation levels, making reliability an important issue in the design. Six or eight boards per calorimeter module each receive and digitize high and low gain signals from six PMTs every 25 ns. Two custom designed gate arrays on each board store the data in digital pipelines until validated by the first level trigger. Selected data are formatted and read out for use by the DAQ and second level trigger systems. Configuration and control commands are distributed to the digitizer boards via the TTC clock distribution system. The current digitizer design was developed for test beam tests during summer 1999, and the final system is scheduled for volume production in the beginning of 2000.

An early slice prototype for the upgraded readout electronics of TileCal

We have developed a slice prototype of the full TileCal readout chain based on prototype modules and off-the-shelf components. As different module prototypes are developed and become available they can replace earlier prototypes or emulators in the chain. Due to its modular and flexible structure, the prototype can adapt to changing requirements. This will allow most of the final functionality to be developed and tested before the hardware design is finalized.

A mobile data acquisition system

A mobile data aquisition (MobiDAQ) was developed for the ATLAS central hadronic calorimeter (TileCal). MobiDAQ has been designed in order to test the functionalities of the TileCal front-end electronics and to acquire calibration data before the final back-end electronics were built and tested. MobiDAQ was also used to record the first cosmic ray events acquired by an ATLAS subdetector in the underground experimental area.

Reliable and redundant FPGA based read-out design in the ATLAS TileCal demonstrator

The current ATLAS Tile Calorimeter read-out system is scheduled for replacement around 2023 due to old age and higher performance needs. The new proposed system is designed to be radiation tolerant, modular, redundant and reconfigurable. To achieve full detector read-out, Kintex-7 FPGAs from Xilinx will be used, in addition to multiple 10 Gb/s optical read-out links. During 2015/2016, a hybrid demonstrator system including the new read-out system will be installed in one slice of the ATLAS Tile Calorimeter to evaluate the new design. This paper describes different firmware strategies along with their integration in the demonstrator in the context of high reliability protection against hardware malfunction and radiation induced errors.