Gadolinium-148 and Other Spallation Production Cross Section Measurements for Accelerator Target Facilities

Accelerator target;Spallation product;Cross section;Spectroscopy;Aluminum activation

Kelley, Karen Corzine ; Nuclear engineering

University:Georgia Institute of Technology

Department:Nuclear engineering

关键词: Accelerator target;    Spallation product;    Cross section;    Spectroscopy;    Aluminum activation;   

Others  :  https://smartech.gatech.edu/bitstream/1853/5143/1/kelley_karen_c_200405_phd.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

At the Los Alamos Neutron Science Center accelerator complex, protons are acceleratedto 800 MeV and directed to two tungsten targets, Target 4 at the Weapons Neutron Researchfacility and the 1L target at the Lujan Center. The Department of Energy requires hazardclassification analyses to be performed on these targets and places limits on certain radionuclideinventories in the targets to avoid characterizing the facilities as nuclear facilities.Gadolinium-148 is a radionuclide created from the spallation of tungsten. Allowed isotopicinventories are particularly low for this isotope because it is an alpha-particle emitter witha 75-year half-life. The activity level of Gadolinium-148 is low, but it encompasses almosttwo-thirds of the total dose burden for the two tungsten targets based on present yield estimates.From a hazard classification standpoint, this severely limits the lifetime of thesetungsten targets. The cross section is not well-established experimentally and this is themotivation for measuring the Gadolinium-148 production cross section from tungsten.In a series of experiments at the Weapons Neutron Research facility, Gadolinium-148production was measured for 600- and 800-MeV protons on tungsten, tantalum, and gold.These experiments used 3 m thin tungsten, tantalum, and gold foils and 10 m thin aluminumactivation foils. In addition, spallation yields were determined for many short-livedand long-lived spallation products with these foils using gamma and alpha spectroscopy andcompared with predictions of the Los Alamos National Laboratory codes CEM2k+GEM2and MCNPX.The cumulative Gadolinium-148 production cross section measured from tantalum, tungsten,and gold for incident 600-MeV protons were 15.24.0, 8.310.92, and 0.5910.155,respectively. The average production cross sections measured at 800 MeV were 28.63.5,19.41.8, and 3.690.50 for tantalum, tungsten, and gold, respectively. These cumulativemeasurements compared best with Bertini and were within a factor of two to three ofCEM2k+GEM2.