2016-12-5 11:14 科学研究处报告题目：Exploring the prospects for heavy and superheavy element production in the reactions of 197Au and 238U with 232Th - a progress report
报 告 人： Joseph B. Natowitz（Texas A&M University, USA）
In recent years considerable effort has been focused on extension of the periodic table to higher atomic number. Accelerator production of new elements has extended the periodic table to atomic number 118 . The synthesis technique which is typically used is fusion of a heavy target with a heavy ion projectile. The net production probability for nuclei which survive fission is found to decrease approximately one order of magnitude for each two units of increase in atomic number. For atomic number 118, the cross section is ~ 0.5 picobarns. It is possible that other mechanisms, such as multi-nucleon transfer or very asymmetric fission of even heavier transient systems, would have more favorable cross sections for production of new nuclei.To pursue investigations of such reactions for the overshoot or multinucleon transfer methods for creating new super- and possibly hyper-heavy nuclei we constructed, together with colleagues at the Jagellonian University, Krakow and Silesian University, Katowice, an experimental array consisting of a forward array of YAP scintillators to collect recoiling heavy nuclei and ionization Chambers at backward angles to search for emission of high energy alpha particles characteristic of the heavy elements.
Joseph B. Natowitz is a University Distinguished Professor Emeritus at Texas A&M University. He served as Head of Chemistry from 1982-1985 and Director of the Cyclotron Institute from 1991-2003. From 2004 to 2014 he held the Bright Chair in Nuclear Science. He is a Fellow of the American Physical Society, a Fellow of the American Chemical society and a Foreign Member of The Mexican Academy of Sciences. He has received an Alexander Von Humboldt Foundation Award, a Distinguished Achievement Award in Research from Texas A&M University, The American Chemical Society Award in Nuclear Chemistry, and the American Chemical Society Southwest Regional Award. He has served, and continues to serve on a number of Scientific Advisory Committees in the U.S. and abroad.