Neutron capture cross section measurement of I and I using the NaI(Tl) spectrometer of the ANNRI beamline at J-PARC

Rovira Leveroni, G.   ; Kimura, Atsushi   ; Nakamura, Shoji  ; Endo, Shunsuke   ; Iwamoto, Osamu  ; Iwamoto, Nobuyuki  ; Toh, Yosuke   ; Segawa, Mariko   ; Maeda, Makoto  ; Katabuchi, Tatsuya*

The neutron capture cross section of I and I were measured from the thermal to the keV energy region with the NaI(Tl) spectrometer of the Accurate Neutron-Nucleus Reaction Measurement Instrument beamline in the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex. The neutron capture yield was determined by means of the total energy detection principle with the pulse-height weighting technique. The present cross section results for I were normalized using the saturated resonance method with a thick-enough Au and provide good agreement with JENDL-5 from thermal to about 500 keV. A resonance analysis with the REFIT code was performed and the resonance parameters for I below 310 eV are presented in this work. In the case of I, the three largest resonances of I were employed for the cross section normalization. The present results for I are the first experimental data for the neutron region between thermal and 20 eV. The present data display a different energy dependence than that in the JENDL-5 and JEFF-3.3 and much similar to that in ENDF/B-VIII.0. Notwithstanding, good agreement was found at the thermal region between the present measurement of 31.6 1.3 b and both evaluated and most experimental data.