medium section
4.An exact expression for calculating the in-medium A absorption cross section is obtained within the framework of the self-consistent relativistic BUU approach. The medium effects on the △N→ NN cross section is investigated, and it is found that the effective cross sation is suppressed in the medium near the threshold energy. The results are in a good agreement with the most recent experimental data of the TAPS collaboration.
5.MECHANICAL STOPWATCH is the time-measuring instrumentation specially for measuring the medium-sized and short time-section, easy to use.
6.The calculation results show that the correlation between the multiplicity of intermediate mass fragments N(subscript IMF) and total number of charged particles N(subscript c) is a sensitive observable for probing the isospin-dependent in-medium nucleon-nucleon cross section, but the isospin effects of symmetric potential on N(subscript IMF) is not obvious in the chosen energy region.

