Experimental Elementary Particle Physics
The Atlas Project
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Arizona Atlas

The Forward Calorimeter Prototype 1995

After the first proof of principle in 1993 (see Prototype 93 Homepage) and acceptance of our novel liquid argon calorimeter design by ATLAS early 1994, we designed and built an extended second prototype, now with full longitudinal containment at ATLAS design depth (45 cm or about 25 radiation length) and 374 electrodes. This module was subjected to extensive testbeam studies at CERN's SPS in summer 1995, this time concentrating on high energy (10 to 200 GeV) electrons. The goal of this experiment was to determine first reliable performance numbers for the electromagnetic signals in the ATLAS forward region, including a sufficient energy and angular resolution. Again, the prototype showed performance beyond expectations, see:

Also, our ATLAS Forward Calorimeter collaborators from the Universities of Carleton (Ottawa, Canada) and Toronto (Canada), and the Institute for Theoretical and Experimental Physics (ITEP) in Moscow (Russia) joined us for the first time in a beam experiment.

Electrode DesignFCAL Prototype 1995
Electrode Design
FCAL Prototype 1995

Chart with variation of prototype respone.

The picture above shows the variation of the FCAL prototype response to 193 GeV electrons as a function of the impact point coordinates (x,y), for perpendicular (0 degrees) and shallow angle (3.6 degrees) input directions. These variations have been determined quantitatively from calorimeter data alone and used to correct the signal for the impact point dependencies. In case of perpendicular impact one clearly sees the tube structure of the group of four electrodes in the signal response.

Experimental Elementary Particle Physics Departmental Telephone: (520) 626-9677