title: Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device.
abstract: We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields.
authors.affiliation: a  Radiological Research Accelerator Facility, Columbia University, Irvington, New York 10533 and.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Xu
authors.affiliation: a  Radiological Research Accelerator Facility, Columbia University, Irvington, New York 10533 and.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Randers-Pehrson
authors.affiliation: b  Center for Radiological Research, Columbia University, New York, New York 10032.
authors.forename: Helen C
authors.initials: HC
authors.lastname: Turner
authors.affiliation: a  Radiological Research Accelerator Facility, Columbia University, Irvington, New York 10533 and.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Marino
authors.affiliation: a  Radiological Research Accelerator Facility, Columbia University, Irvington, New York 10533 and.
authors.forename: Charles R
authors.initials: CR
authors.lastname: Geard
authors.affiliation: b  Center for Radiological Research, Columbia University, New York, New York 10032.
authors.forename: David J
authors.initials: DJ
authors.lastname: Brenner
authors.affiliation: a  Radiological Research Accelerator Facility, Columbia University, Irvington, New York 10533 and.
authors.forename: Guy
authors.initials: G
authors.lastname: Garty
mesh_terms: D000818:Animals; D006801:Humans; D015162:Micronucleus Tests; D008954:Models, Biological; D009502:Neutrons; D009689:Nuclear Warfare