US-Federal Republic of Germany Cooperative Research: Bombarding Energy Dependence of Multi-fragmentation

该奖项支持密歇根州立大学的William G.Lynch博士、C.Konrad Gelbke博士和其他人与法兰克福大学的Uli Lynen博士、W.Trautmann博士和J.Pochodzalla博士以及法兰克福达姆施塔特的Gesellschaft Fuer&gt；Schwerion enforschung(GSI)合作进行物理研究。他们正在研究多碎片破碎机制的性质，以获得有关稀核物质的状态方程和液体、气体相变的信息。MSU有一个紧凑和高度颗粒化的中等质量碎片探测阵列，即微型球。使用该设备进行测量需要小的无晕无氪光束，其能量水平和质量在美国是无法获得的。这种光束将在不久的将来在GSI提供，这将是世界上同类设备中最好的；然而，在GSI还没有类似小型球的阵列。因此，合作的基础是将阵列运送到德国，将这两个互补的最先进设备结合在一起。计算表明，在很宽的入射能量范围内，重离子反应可能会发生多重碎裂。到目前为止，很少有测量涉及导致产生许多中等质量碎片的碰撞的性质。小球的建造是为了寻找中等质量的碎片，并提供关于高度激发和稀薄核物质的信息。与阿拉丁光谱仪配合使用，将有可能在50至1000 MeV的能量范围内测量氪诱导反应的多重碎裂过程。这一范围的研究将补充密歇根州立大学正在进行的研究工作，那里正在探索较低能量的反应。他们对Kr.Nb系统的初步调查结果将对随后的重离子实验方向产生重大影响。一旦确定了多碎片破碎机制占主导地位的入射能量，将与动力学和统计多碎片模型进行详细的比较。

This award supports Drs. William G. Lynch, C. Konrad Gelbke and others of Michigan State University to collaborate in physics research with Drs. Uli Lynen, W. Trautmann and J. Pochodzalla of the University of Frankfurt and the Gesellschaft fuer >Schwerionenforschung (GSI) at Darmstadt, FRG. They are >investigating the properties of multifragment breakup mechanisms in order to obtain information about the equation of state and liquid.gas phase transition of dilute nuclear matter. MSU has a compact and highly granular intermediate mass fragment detection array, the MINIBALL. Measurements with this device require small halo.free Krypton beams at an energy level and quality not available in the U.S. Such beams will be available in the near future at GSI, which will be the best facility of its kind in the world; however, there is no array similar to MINIBALL at GSI. The collaboration, therefore, is based on transporting the array to Germany to bring these two complementary state of the art devices together. Calculations suggest that multifragmentation may occur in heavy ion reactions over a wide range of incident energies. Few measurements to date have addressed the properties of collisions which lead to the production of many intermediate mass fragments. MINIBALL was constructed to look for intermediate mass fragments and provide information about highly excited and dilute nuclear matter. In conjunction with the ALADIN spectrometer, it will be possible to measure multifragmentation processes for Krypton induced reactions over the energy range 50 to 1000 MeV. Studies in this range will complement the ongoing research effort at MSU where reactions at lower energies are being explored. The results of their initial survey of the Kr.Nb system will have a significant impact on the directions of subsequent heavy ion experiments. Once incident energies at which multifragment breakup mechanisms are dominant have been identified, detailed comparisons to dynamical and statistical multifragmentation models will be performed.