Measurement of thick target neutron energy spectra at 15 and 90 bombarded with 120-GeV protons

Iwamoto, Yosuke   ; Sanami, Toshiya*; Kajimoto, Tsuyoshi*; Shigyo, Nobuhiro*; Hagiwara, Masayuki*; Lee, H. S.*; Soha, A.*; Ramberg, E.*; Coleman, R.*; Jensen, D.*; Leveling, A.*; Mokhov, N.*; Boehnlein, D.*; Vaziri, K.*; Sakamoto, Yukio; Nakashima, Hiroshi

Neutron energy spectra at 15 and 90 produced from carbon, aluminum, copper and tungsten targets bombarded with 120-GeV protons were measured at Fermilab Test Beam Facility (FTBF) for the validation of simulation codes. The target thicknesses were 60 cm for graphite, 50 cm for aluminum, 20, 40, and 60 cm for copper and 10 cm for tungsten, respectively. The neutron time-of-flight measurements were performed using an NE213 organic liquid scintillator at 5.2 m for 90 and 8.0 m for 15 measuring from the center of the target to the surface of the detector. The raw signals (waveforms) obtained from photomultiplier tubes were recorded using the 10 bit digitizer (Agilent-acqiris DC282) with 0.5 ns sampling and 500 ns duration. To compare the experimental results, Monte Carlo calculations with the PHITS, MARS and FLUKA codes were performed. It was found that these calculated results underestimate the experimental results in the whole energy range.