For the Sun and the solar neutrinos the models and data by John Bahcall is used. The predictions for the experiments are calculated by computing the expected neutrino fluxes within the sensitivity of the experiments. The code uses tabulated cross sections and solar fluxes, sums over the energy spectrum, and takes the neutral currents into account in water detectors. Nothing special, all straight forward. It probably works for less than minimal machines, but then I cannot guarantee that it is useful for anything.
More power is desirable for excessive studies of complicated matter conversion scenarios.
A PC with Pentium Pro, or a risc-based workstation is recommended. Note that a good software is essential to run the Java code. Outdated Java browser without a good JIT compiler can freeze even a supercomputer. Power users may load the classes on their disk and run them directly. A good java applet viewer may perform better than web browser, and some systems allow a compilation to machine code.