Measurement of thick target neutron energy spectra bombarded

Measurement of thick target neutron energy spectra bombarded with 120 -Ge. V protons Y. Iwamoto 1, T. Sanami 2, T. Kajimoto 3, N. Shigyo 3, M. Hagiwara 2, H. S. Lee 4, D. Boehnlein 5, R. Coleman 5, D. Jensen 5, A. Leveling 5, N. V. Mokhov 5, E. Ramberg 5, A. Soha 5, K. Vaziri 5, Y. Sakamoto 1, H. Nakashima 1 1 Japan Atomic Energy Agency, 2 KEK, 3 Kyushu University, 4 Pohang Accelerator Laboratory, 5 Fermi National Accelerator Laboratory 1

Introduction Validation of high-energy particle transportation codes for “neutron production on source” Beam Sample Detector Comment Agosteo et al CERN 40 Ge. V/c Mixed beam proton/pion+ 158 Ge. V/c Pb Cu, Ag, Pb 5 x 2. 5 cm Bonner Ext. E Bonner Unfolding Protons are subtracted by calc. Present FNAL 120 Ge. V proton C 50 cm Al 50 cm Cu 20, 40, 60 cm W 10 cm NE 213 TOF at 15, 30, 60, 90, 120, 15 0 o Wendi at 60, 90, 170 o Direct Mes. Shadow bar Close by dump ØExperimental neutron data for 100 Ge. V proton incident reaction are scarce. Purpose: Measurement of neutron energy spectra at 15 o and 90 o from 120 Ge. V proton induced reaction using TOF method. 2

Measurement Fermilab Test Beam Facility (FTBF) MT 6 SEC 2 3

Experiments ØDetector: Liquid organic scintillator NE 213 ØTime-of-Flight (TOF) method: beam pulse – detector signal ØTarget: 50 cm thick x 7 cm Al, 10 cm thick x 3 cm W, 20, 40 cm thick x 5 cm Cu Target Size (cm) Energy loss (Ge. V) Al 3. 5 x 50 0. 29 Cu 5 x 20 0. 36 Cu 5 x 40 0. 71 W 3 x 10 0. 33 Forward angle Backward angle Ø 1 m thick iron shadowbar for measurement of room-scattered neutrons. 4

u. Beam structure u. Electronics 19 ns 20 -36 bunches 11 us Wave Form (WF) data taking • Neutron trigger • 2 GHz sampling • 2 -coin. beam monitor • 2 -gain record for PSD • CFD trigger for low threshold • Beam – NE coin for BG reduction • Recording beam monitor WFs 5

Neutron and Gamma-ray separation by WF 6

TOF vs Light output Single proton events All events proton pion neutron photon 19 ns ØEnergy resolution : ~30% at 1 Ge. V neutron for 20 cm thick Cu at 15 o and 8. 0 m ØCount‐loss due to multi proton event: ~10% ØDetection Eff. (Scinful. QMD): ~15% for high energy 7

Benchmark calculation Characteristics of inelastic hadron-nucleus interactions Code PHITS FLUKA MARS High-energy (> -5 Ge. V/c) Low-energy (< ~5 Ge. V/c) Intra nuclear-cascade Hadronic cascade model JAM model Bertini Preequilibrium. Glauber-Gribov multiple scattering cascade model PEANUT Cascade-exciton Los Alamos Quak-Gluon String Model model CEM 8

10 cm thick tungsten The difference between PHITS, FLUKA and MRAS results is almost negligible. ØAt 15 o, the calculated results agree well with experimental data. ØAt 90 o, calculated results underestimate the experimental data. ØThis may be resulted from the strong forward emission of particles in the high-energy physics model. 9

20 cm thick copper The tendency of the relation between calculated and experimental results is almost same with that for a 10 -cm-thick tungsten target. 10

40 cm thick copper ØAt 15 o, the calculated results agree well with experimental data. ØAt 90 o, the difference between calculated results and experimental data is larger than that for 20 -cm-thick copper target. ØIt seems that a thicker target enhances the disagreement at 90 o due to the strong emission to the forward angle in physics model. 11

50 cm thick aluminum ØThe statistics of experimental data was not enough. ØIn general, calculated results give agreement with experimental data. 12

Summary ØNeutron energy spectra at 15 o and 90 o produced from 10 cm thick tungsten, 20 and 40 cm thick copper, and 50 cm aluminum targets bombarded with 120 Ge. V protons were measured at FTBF. ØThe neutron time-of-flight measurements were performed using an NE 213 organic liquid scintillator at 8. 0 m for 15 o and 5. 2 m for 90 o. ØThe waveforms were recorded using the 10 bit digitizer. ØTo compare the experimental results, Monte Carlo calculations with the PHITS, FLUKA and MARS codes were performed. ØAll calculated results at 15 o gives good agreement with the data, while these calculated results at 90 o underestimate the experimental results due to the strong forward emission of particles in the models. 13