Figure 1:The Pyramid PPAC array
Figure 1:The Pyramid PPAC array
The Pyramid consists of three position sensitive parallel plate avalanche counters covering a solid angle of 1.8pi within a scattering angle region of 74 - 162 degree. The counters can be equipped alternatively with two kinds of position sensitive cathodes: 1. Resistive layer cathode enable a position resolution of about 2mm throughout the active area of 78cm^2. This concept was applied in different GASP experiments. 2. Segmented multi-layer cathodes with integrated double-meander delay-line structures have been used during experiments of the Euroball-at-GSI campaign. A position resolution of about 1mm has been achieved in tests.
[1] K. Vetter et al.; A position sensitive gas counter with
resistive layer cathode decoded by a neural network algorithm, Nucl.
Instr. and Meth. A344 (1994) 607.
The Fiber detector
The experiments
with radioactive beams at relativistic energies require
pre- and post-target tracking of each beam ion. For this purpose large
area (50cm^2 x 50cm^2) arrangements of scintillator fibers have been
developed in collaboration with the LAND
group. The position resolution
corresponds to the fiber diameter of 1mm. The 500 fibers are coupled to
a position sensitive photomultiplier to read-out the light signal of the
fiber hit by a particle. The method has a large dynamical range enabling
the detection of particles with Z values between 3 and 111. Moreover,
high count rates up to 10^5 particles/s are possible.
