PAC09 - List of Authors (Niita, K.)

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Niita, K.

Paper	Title	Page
TU6RFP058	Neutron Energy Spectra and Dose Equivalent Rates from Heavy-Ion Reactions below 20 MeV/u Using the PHITS Code	1683
	Y. Iwamoto JAEA, Ibaraki-ken K. Niita RIST, Ibaraki R.M. Ronningen NSCL, East Lansing, Michigan
	Funding: The funding information for R.M. Ronningen is U.S. Department of Energy Grant Number DE-FG02-08ER41548. The Particle and Heavy Ion Transport Code (PHITS)* has been typically used to predict radiation levels around high-energy (above 100 MeV/u) heavy-ion accelerator facilities. However, predictions of radiation levels around low-energy (around 10 MeV/u) heavy-ion facilities are also desirable, but the reliability of PHITS at low energies has not been investigated. In this work, neutron energy spectra from 10 MeV/u 12C and 16O ions incident on C and Cu targets have been calculated using the quantum molecular dynamics (QMD) model coupled to the generalized evaporation model (GEM) in PHITS. In particular, the influence of the “switching time”, defined as the time when the QMD calculation is stopped and the calculation switches to the GEM model, was studied. The calculated neutron energy spectra obtained using a value of 100 fm/c for the switching time agree well with the experimental data. We have also used PHITS to simulate an experimental study by Ohnesorge et al.*, by calculating neutron dose equivalent rates, for 3-16 MeV/u 12C, 16O and 20Ne beams incident on Fe, Ni and Cu targets. The calculated neutron dose equivalent rates agree well with the data. H. Iwase, K. Niita and T. Nakamura, J. Nucl. Sci. Technol. 39, 1142 (2002). **W.F. Ohnesorge, H.M.Butler, C.B.Fulmer and S.W.Mosko, Health Physics 39, 633 (1980).

Paper

Title

Page

TU6RFP058

Neutron Energy Spectra and Dose Equivalent Rates from Heavy-Ion Reactions below 20 MeV/u Using the PHITS Code

1683

Y. Iwamoto
JAEA, Ibaraki-ken
K. Niita
RIST, Ibaraki
R.M. Ronningen
NSCL, East Lansing, Michigan

Funding: The funding information for R.M. Ronningen is U.S. Department of Energy Grant Number DE-FG02-08ER41548.

The Particle and Heavy Ion Transport Code (PHITS)* has been typically used to predict radiation levels around high-energy (above 100 MeV/u) heavy-ion accelerator facilities. However, predictions of radiation levels around low-energy (around 10 MeV/u) heavy-ion facilities are also desirable, but the reliability of PHITS at low energies has not been investigated. In this work, neutron energy spectra from 10 MeV/u 12C and 16O ions incident on C and Cu targets have been calculated using the quantum molecular dynamics (QMD) model coupled to the generalized evaporation model (GEM) in PHITS. In particular, the influence of the “switching time”, defined as the time when the QMD calculation is stopped and the calculation switches to the GEM model, was studied. The calculated neutron energy spectra obtained using a value of 100 fm/c for the switching time agree well with the experimental data. We have also used PHITS to simulate an experimental study by Ohnesorge et al.**, by calculating neutron dose equivalent rates, for 3-16 MeV/u 12C, 16O and 20Ne beams incident on Fe, Ni and Cu targets. The calculated neutron dose equivalent rates agree well with the data.

*H. Iwase, K. Niita and T. Nakamura, J. Nucl. Sci. Technol. 39, 1142 (2002).
**W.F. Ohnesorge, H.M.Butler, C.B.Fulmer and S.W.Mosko, Health Physics 39, 633 (1980).