The Parity Experiment at the Bonn Isochronous Cyclotron |
Welcome to the Parity Experiment Spokesperson: PD Dr. P.D. Eversheim |
The parity experiment at the Bonn Isochronous Cyclotron probed the weak
interaction in a pure hadronic channel i.e.
scattering. This kind of
experiment was proposed in 1972 by Simonius [1] and has the advantage of a
relatively simple theoretical interpretation at the expense of the accuracy (some
10-8) the longitudinal analyzing power Az has to be
measured. As this kind of test constitutes a null-experiment the sensitivity is
risen by 2-3 orders of magnitude. Moreover, since a polarization observable is
measured no absolute cross-sections have to be determined. In order to suppress drifts of parameters
all means of
correlations in the time-domain can be
applied, improving the sensitivity by another 2-3 orders of magnitude.
The experiment at Bonn was planned in 1980 and
carried out until June 1991 with the final result
Az
= (-0.93±0.20±0.05)·10-7[
2,20]. After a first stage (1985)
tests demonstrated the feasibility of the experiment, resulting in improvements
of the source for polarized protons, the beam-line, experimental set-up and data
acquisition. Finally, the ratio of time used for care of the source, accelerator
and beam-handling to the time spent for data-taking could be improved from 80/20
to 10/90. Intermediate results can be found in [3,4]. In all, 16 diploma theses
[5-20] and 2 PhD theses [21,22] have contributed to the experiment.
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