Shuichi Ishikura

Mercury Target and Its Peripheral Devices for 1 MW Spallation Neutron Source

The Japan Atomic Energy Research Institute (JAERI) and the High Energy Accelerator Research Organization (KEK) are promoting a plan to construct a 1MW neutron source facility at the Tokai Research Establishment, JAERI, under the Japan Proton Accelerator Research Complex (J-PARC) Project. In the facility, 1 MW pulsed proton beam from a high-intensity proton accelerator will be injected into a mercury target in order to produce high-intensity pulse neutrons for use in the fields of life and material sciences. In order to realize such a high-power neutron source, the design activity of a cross flow type (CFT) mercury target and its peripheral devices has continued and the results is reflected in the ordering specifications of the facility construction. The arrangement of each component and their structure was optimized through experimental and analytical studies. In this paper, the present design of the mercury target components for 1MW spallation neutron source including the target vessel, a mercury circulation system, and a target trolley will be reported.Copyright

Stress waves due to deposited heat in mercury and lead spallation targets

Stress waves resulting from deposited heat in mercury and lead spallation targets were studied. A computation was carried out with the following conditions: —the incident proton energy and current are 1.5 GeV and 3.3 mA, respectively: the total proton energy is 5 MW in short pulses at a frequency of 50 Hz —targets are mercury and lead —proton beam profile has a Gaussian distribution. The following results are obtained: 1. It is found that the cylindrical part of the container expands due to stress waves with periods of 180 μs for mercury and 130 μs for lead. The periods are roughly evaluated by D/V, where D is the diameter of target container, 0.2 m, and V the speed of sound in fluid materials. 2. Membrane components of stress control large amplitude stress waves, whilst bending stress components induce high frequency stress waves in both targets. 3. A fitting function describing deposited energy as, a function of position in the target was proposed. The ratio of deposited energy to the projectile energy is under 50% for 1.5 GeV protons for both targets.