To produce hypernuclei, intense pion and kaon beams in the 1 GeV/c region are required. The most intense and pure low-energy separated beams are available at the Brookhaven AGS and they are attracting collaborative proposals from around the world. Several proposals involve moving existing detector systems to Brookhaven and others involve the construction of new and innovative detectors.
The goal of measuring the level spectra and decay properties of S=-1 and S=-2 hypernuclei is to test the energies and wave functions from microscopic structure models. The experimentally determined properties of hypernuclei can then be used to put constraints on baryon-baryon interaction models which link NN, YN and YY interactions. These interactions are not well determined by the sparse data on free two-body interactions outside the NN sector, and such information is crucial. The weak two-body interaction involving hyperons, which provides the predominant non-mesonic, weak-decay mode of most hypernuclei, can only be studied in the environment of a hypernucleus. This represents a unique test of the Delta I =1/2 rule for weak decays, and provides a link to fundamental issues in particle physics.
These promising lines of research require two beam lines providing pion and kaons of the appropriate momentum range. For (K,pi) and (pi,K) studies of singly-strange systems the kinematical and production contraints dictate the use of meson beams of around 1.0 GeV/c. For doubly-strange systems, a beam between 1.6 and 2.0 GeV/c is most suitable.
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