Our tasks, responsibility and preliminary status quo
in ATLAS experiment


The main goal of the ATLAS experiment is looking for the experimental evidence of Higgs particle and the investigation of the properties of matter in the region 1 TeV (physics beyond Standard Model, MSSM, SUSY). This last point after HERA results is more actual and attractive.
Calorimeters will play a crucial role at LHC. In contrast to other detectors their intrinsic resolution improves with energy, which makes them very suitable detectors at high energy machines. An important aspect of the Hadronic End-Cap (HEC) is its ability to detect muons, and to measure any radiative energy loss.
The Hadronic End-Cap is designed to provide coverage for hadronic showers in the range 1.55 < eta < 3.2. The HEC detector elements are located in the end-cap cryostat at either end of the ATLAS tracking volume. It is a liquid argon (LAr) sampling calorimeter with copper-plate absorber (with the thickness 25/50 mm). This technology was selected as it allows a simple mechanical design to be produced that is radiation resistant and covers the required area in a cost-effective way.
The gaps between the copper plates (8.5 mm) are instrumented with a read-out structure forming an electrostatic transformer (EST), see fig 1.

Figure 1: Hadronic end-cap EST (cell)

This structure optimizes the signal-to-noise ratio while reducing the high-voltage requirements and ionization pile-up, and limiting the effect of failure modes such as high-voltage sparks and shorts.
The signals are amplified and summed employing the concept of "active pads": the signals from two consecutive pads are fed into separate amplifiers (based on GaAs electronics) and summed to read-out channels. The use of cryogenic GaAs preamplifiers provides the optimum signal-to-noise ratio for the HEC. The boards with the GaAs chips are mounted on the outer radius of the HEC. The use of cryogenic GaAs preamplifiers provides the optimum signal-to-noise ratio for the HEC.

Our primary goal in ATLAS experiment is the proposal and the development of the calibration system for HEC calorimeter.

Our responsibilities can be described by the following way:

Juridical background