ANNRI for science on neutron-neucleus reaction

The ANNRI is the abbreviation of Accurate Neutron-Nucleus Reaction measurement Instrument. It was constructed in order to supply accurate neutron capture cross sections of minor actinides and fission products required for developing innovative nuclear systems.

The ANNRI project team has developed the neutron beam line optimized for neutron time-of-flight experiments, the advanced Ge and NaI spectrometers for detecting prompt gamma rays, and the measurement method of neutron capture cross sections. The team has started the measurements of neutron capture cross sections since 2009, and successfully obtained the neutron capture cross section of 244Cm at the resonance energy region in 2010 [2]. This is the first experiment in the world, performed by using the worldfs strongest pulsed-neutron beam, except the nuclear bomb experiment.

Figure 1. Inside of the J-PARC/MLF/ANNRI, where the Ge spectrometer are shown.

To commemorate the accomplishment of the ANNRI, the memorial symposium was held at Feb. 2011 in Tokai. About 60 scientists in the field of nuclear data, nuclear astrophysics, trace element analysis got together at the symposium, and discussed the possible future use of the ANNRI. The ANNRI is open for researchers in these fields under the MLF user program from the 2011B term [3].

Figure 2. A photograph of scientists, attended the memorial symposium, on the ANNRI.

[2] S. Goko, A. Kimura, H. Harada, et al., J. Nucl. Sci. Technol. 47 (2010) 1097.