ATLAS Hadronic End-cap Calorimeter Research Articles

Including Calorimeter Test Beams in Geant-val—The Physics Validation Testing Suite of Geant4

The Geant4 simulation toolkit is currently adopted by many particle physics experiments, including those at the Large Hadron Collider and the ones proposed for future lepton and hadron colliders. In the present era of precision tests for the Standard Model and increasingly detailed detectors proposed for the future colliders scenario, Geant4 plays a key role. It is required to remain a reliable and stable toolkit for detector simulations and at the same time undergo major improvements in both physics accuracy and computational performance. Calorimeter beam tests involve various particles at different energy scales and represent ideal benchmarks for the physics modeling and assessment of Monte Carlo tools for radiation–matter simulation. We present the first results of a broad validation campaign on test beam data targeting data deployment and preservation with geant-val, the Geant4 validation and testing suite. We investigate the Geant4 capability to model the calorimeter response, energy fluctuations, and shower shapes using data from the ATLAS hadronic end-cap calorimeter and the CALICE silicon-tungsten calorimeter. The evolution over the recent years of the recommended set of physics processes for high-energy physics applications is outlined and compared to alternative models for hadronic interactions.

Irradiation tests and expected performance of readout electronicsof the ATLAS Hadronic Endcap calorimeter for the HL-LHC

The readout electronics of the ATLAS Hadronic Endcap Calorimeterwill have to withstand an about 3–5 times higher radiation dosesat the future high-luminosity LHC compared to the LHC design values.The radiation damages of the front-end electronics made in GaAs technologycould significantly affect the hadronic endcap calorimeter performance. Recentmeasurements of characteristics of neutron and proton irradiated ASICs atroom and liquid argon temperatures are reported, which allow an improvedassessment of the expected degradation in high-luminosity LHC conditions.The results of these measurements are furthermore applied to simulations ofthe calorimeter performance. Results from replacement technologies, like Si CMOS,are also presented.

Neutron and proton tests of different technologies for the upgrade of cold readout electronics of the ATLAS Hadronic End-cap Calorimeter

The expected increase of total integrated luminosity by a factor ten at the HL-LHC compared to the design goals for LHC essentially eliminates the safety factor for radiation hardness realized at the current cold amplifiers of the ATLAS Hadronic End-cap Calorimeter (HEC). New more radiation hard technologies have been studied: SiGe bipolar, Si CMOS FET and GaAs FET transistors have been irradiated with neutrons up to an integrated fluence of 2.2 · 1016 n/cm2 and with 200 MeV protons up to an integrated fluence of 2.6 · 1014 p/cm2. Comparisons of transistor parameters such as the gain for both types of irradiations are presented.

GEANT4 physics evaluation with testbeam data of the ATLAS hadronic end-cap calorimeter

The validation of GEANT4 physics models is done by comparing experimental data from beam tests of modules of the ATLAS hadronic end-cap calorimeter with GEANT4 based simulations. Various physics lists for the simulation of hadronic showers are evaluated. We present results of studies of the calorimeter performance parameters (like energy resolution and shower shapes) as well as results of investigations of the influence of the Birks' law and of cuts on the time of development of hadronic showers.

Radiation hardness tests of GaAs amplifiers operated in liquid argon in the ATLAS calorimeter

Highly integrated Gallium Arsenide (GaAs) chips of preamplifiers and summing amplifiers have been exposed to high fluence of fast neutrons and γ -dose at the IBR-2 reactor in Dubna. A stable performance of the electronics has been demonstrated up to a fluence of 5 × 10 14 n cm - 2 and a γ -dose of 55 kGy. The radiation hardness tests confirm the applicability of the preamplifiers for more than 10 years operation in the ATLAS hadronic end-cap calorimeter at LHC.

Construction, assembly and testing of the ATLAS hadronic end-cap calorimeter

The construction and assembly of the four wheels of the ATLAShadronic end-cap calorimeter and their insertion into the two end-capcryostats are described. The results of the qualification testsprior to installation of the two cryostats in the ATLAS experimental cavernare reviewed.

GEANT4 physics evaluation with testbeam data of the ATLAS hadronic end-cap calorimeter

We evaluate the validity of the GEANT4 electromagnetic and hadronic physics models by comparing experimental data from beam tests of modules of the ATLAS hadronic end-cap calorimeter with GEANT4-based simulations. Two physics lists (LHEP and QGSP) for the simulation of hadronic showers are evaluated. Calorimeter performance parameters like the energy resolution and shapes of showers are studied both for electrons and charged pions. Furthermore, throughout the paper we compare GEANT4 and the corresponding predictions of GEANT3 used with the G-CALOR code for hadronic shower development.

Cold electronics for the liquid argon hadronic end-cap calorimeter of ATLAS

This paper describes the on-detector electronics of the ATLAS hadronic end-cap calorimeter (HEC). The electronics is operated in liquid argon; therefore attention is paid to its performance at low temperatures. The core of the electronics are Gallium Arsenide (GaAs) preamplifiers. We present design, layout and results of various tests of the preamplifier chips and summing boards. The calibration and signal cables have been studied under laboratory conditions and the signal distortion is modeled. All parts of the electronics have been produced, tested and assembled on the calorimeter modules. The summary of the commissioning tests is presented.

Performance of the ATLAS hadronic end-cap calorimeter in beam tests

Modules of the ATLAS liquid argon Hadronic End-cap Calorimeter (HEC) were exposed to beams of electrons, muons and pions in the energy range 6⩽E⩽200GeV at the CERN SPS. A description of the HEC and of the beam test setup are given. Results on the energy response and resolution are presented and compared with simulations. The ATLAS energy resolution for jets in the end-cap region is inferred and meets the ATLAS requirements.

95/01463 GT-MHR hellum gas turbine power conversion system design and development

Highly integrated Gallium Arsenide (GaAs) chips of preamplifiers and summing amplifiers have been exposed to high fluence of fast neutrons and γ-dose at the IBR-2 reactor in Dubna. A stable performance of the electronics has been demonstrated up to a fluence of 5×1014ncm-2 and a γ-dose of 55 kGy. The radiation hardness tests confirm the applicability of the preamplifiers for more than 10 years operation in the ATLAS hadronic end-cap calorimeter at LHC.