In order to test the concepts for track detection and alignment of the ATLAS Muon Spectrometer two activities are planned:
1) DATCHA 0. Here only the structural chamber elements which carry the alignment systems (in-plane, projective, praxial and axial systems) are mounted on a special support. All the alignment systems will be read out. Due to the redundancy in the data, the performance of the alignment systems can be evaluated by calculating residuals. By means of 'fake muon' alignment systems, the appearent sagittas of artificial infinite-momentum muons is measured. The structural elements ('cross plates') will be displaced and the response of the alignment systems will be recorded.
DATCHA 0 will be located in Saclay.
2) DATCHA 1. Here three full scale prototypes forming a typical 'muon tower' will be mounted on a support. Again, the tower will be fully equipped with the alignment systems. With this tower, the alignment is measured with cosmic rays. The sagittas of individual cosmic rayes will be corrected using the data from the alignment systems. The average corrected sagitta is a measure for the quality of the alignment system. The chambers will be made operational (requiring a readout & DAQ system, HV, gas, detector control systems). A scintillationg hodoscope will be placed close to BIL, while two or three RPC layers with associated electronics will provide for a trigger.
The cross plates forming the DATCHA 0 tower will be placed next to the DATCHA 1 tower. This makes it possible to check the inter-tower alignment systems (axial and praxial).
DATCHA 1 will be located at CERN in the UA1 pit.
Drawings of the DATCHA 0/1 layout
BOL pictures and
technical drawings
BML design and
technical drawings
BIL design and technical drawings
Everything concerning electronics
Information about the RASNIK
alignment system.
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