Prototypes
Several prototypes were built at ODU to address questions about the
mechanical
and chemical properties of Stesalit as a structural material for drift
chambers.
Single cell prototype:
The first prototype was a small test chamber with stesalit endplates.
It contained
a single sense wire, surrounded by 6 field wires and 6 guard wires
each. This prototype
was used to determine the efficiency of the sense wire along its length
and as
a general proof of principle.
Mechanical tests
Several test were done on samples of Stesalit, determining the
mechanical stability
and tensile strength, and the suitability for machining. We found that
Stesalit can
be machined to very good precision.
36-cell prototype:
Stringing of 36-cell prototype
The next prototype was a 6 x 6 array of sense wires, corresponding
to a 6 cell wide
section of a real superlayer, again with stesalit endplates. After it
was fully
strung (see below), we checked the position tolerance of the wires and
their tension.
We then determined the spatial resolution and efficiency of the chamber
with
cosmic rays. The spatial resolution was found to be 0.1 mm, well within
the
0.15 mm specification.
Reconstructed cosmic ray track in the 36-cell prototype
Full-size prototype:
The final prototype (dubbed "Sector 0")
is a full-size wire chamber with about 1000 wires strung. In addition
it contains
pretensioning wires to maintain an overall stress on the endplates
similar to that of
a fully strung chamber. It is equipped with "mock up circuit boards"
and "HV cables".
The purpose of this prototype is to thoroughly test all assembly and
stringing procedures;
it is especially important to test the insertion of a "real" chamber
into the CLAS and
the tension transfer from the exosceleton to the springs.
Sector 0 in the instrumentation clean room
Back to Region 2 Drift Chambers.