Measurement of the energy spectrum of spallation neutron emitted to the most backward angle of 180 produced from thick mercury target irradiated with 3 GeV protons

Matsuda, Hiroki  ; Meigo, Shinichiro   ; Iwamoto, Hiroki   ; Takeshita, Hayato*

Even though the neutron spectrum produced to most backward along the proton beam direction is essential for the shield design for Accelerator-Driven System (ADS) and high-intensity spallation neutron source, the experimental data are scarce. For the validation of source term of radiation, we have measured the energy spectrum of the neutron emitted to the most backward angle of 180 produced from mercury target irradiated with 3 GeV proton at the Material Life Science Experimental Facility (MLF) in J-PARC. In the experiment, the spectrum was measured by time-of-flight (TOF) method with the liquid scintillator (NE213) placed at the upstream of the bending magnet with flight-path of 126 m to the mercury target in order to obtain high energy resolution. In order to obtain low energy neutron around at 1 MeV, a small scintillator was employed. The neutron detection efficiency was calculated with the SCINFUL-R code with the correction of experimental result with Cf source in low energy region less than 10 MeV. It was found that the PHITS calculation with INCL4.6 and GEM is in good agreement with the experiment in the energy reason less than 20 MeV.