JAEA-Conf 2011-002 - 日本原子力研究開発機構

JAEA-Conf 2011-002
[3] Measurements of neutron-capture cross sections of MAs and LLFPs have been started. Some
very preliminary neutron-capture cross sections were reported in the 2010 International
Conference on Nuclear Data for Science and Technology (ND2010) and a rapid communication.
[4-7] In this part (1), a brief view of ANNRI and, as examples of the measurements of the MAs,
preliminary neutron-capture cross sections of 244Cm and 246Cm were reported.
2. A brief view of ANNRI
2.1 ANNRI Beam Line
A new experimental apparatus, ANNRI, is located
on the Beam Line No. 04 of the MLF in the J-PARC. Fig. 1
shows a photo of ANNRI and Fig. 2 shows a schematic view
of ANNRI. The neutron beam goes through a T0 chopper, a
neutron filter, a double disk chopper, and a rotary collimator
and two experimental areas, and then is dumped into a beam
stopper. There are two detector systems in ANNRI. One is a
large germanium (Ge)-detectors array named “4π Ge
spectrometer”. The “4π Ge spectrometer” is the main detector
of ANNRI and located at a flight-length of 21.5 m. The other
one is a NaI spectrometer located at a flight-length of 27.9 m.
Using the NaI spectrometer, a reliable analysis is possible by
the established pulse-height weighting technique.[8] The most
downstream collimator, “rotary collimator”, defines the spatial
Fig.1. An outward appearance
of ANNRI
Fig. 2. A schematic view of ANNRI. There are two detector systems in ANNRI. “4π Ge
spectrometer” is the main detector of ANNRI and located at a flight-length of 21.5 m. A NaI
spectrometer located at a flight-length of 27.9 m.