Experimental kerma coefficients of biologically important materials at neutron energies below 75 MeV

Abstract

The present work summarizes our results already published on cross sections and partial kerma coefficients for hydrogen, carbon, and oxygen and then applies them for determining experimental partial and total kerma coefficients of composite biologically important materials. Double-differential cross sections for light-charged particle production (proton, deuteron, triton, and alpha particle) induced by fast neutrons on hydrogen, carbon, and oxygen have been experimentally measured at several incident energies from 25 to 75 MeV. The measurements covered the laboratory angular range 20 degrees to 160 degrees and were extended to very forward and very backward angles by using a reliable extrapolation procedure. Energy-differential, angle-differential, and total production cross sections were derived from the measured data. The experimental methods and data reduction procedures are briefly presented here. The experimental cross sections were compared to existing data in the literature for nucleon-induced reactions and against prediction of nuclear models. Partial and total elemental kerma coefficients were deduced on the basis of the measured cross sections. Procedures for extrapolating the partial kerma coefficients down to the reaction threshold energies for each of the measured ejectile species have been applied to carbon and oxygen. A simple-to-use analytical formula to describe the experimental hydrogen kerma coefficients was proposed which provides the recoil kerma coefficients in the incident neutron energy range 0.3 to 100 MeV. The present article reports for the first time experimental partial kerma coefficients for composite materials of biological interest. Resulting total kerma coefficients are compared to theoretical predictions and to other experimental data.

Neutron-induced reaction cross-section measurements using a small multi-detector array and description of a large array

“…A wealth of results have been already obtained with the following setup and have been published elsewhere [2][3][4][5][6]. As example, figure 5 shows, in 3-D representation, the complete measured angular distributions of proton energy spectra for Al.…”

“…For all targets, derived experimental data as energy-differential, angle-differential and total production cross-sections are obtained by integration over the angle and/or the ejectile energy of the double-differential cross-sections. This type of data offers an important experimental base both for fundamental research and for many applications [6]. These data can be used for testing the nuclear reaction models; they also offer a wealth of information concerning the nuclear structure of the involved nuclei.…”

New calculation method of neutron kerma coefficients for carbon and oxygen below 30 MeV

“…The partial kerma coefficients of the various secondary charged particles below 30 MeV according to formula (4) for carbon and oxygen are given in Figs. 1 and 2, respectively.…”

“…[31] at 27.4 MeV are not corrected for the contributions from the ejectile energies below the experimental low-energy cuts in the measured spectra, as mentioned in Ref. [4]. Therefore, the extrapolated partial kerma coefficients (full dots) down to the thresholds are experimental in the sense that no theoretical concept was used in their determination [4].…”

“…Unfortunately, below 30 MeV, the double-differential cross sections of the ejectile, even including the neutron, are sparse for carbon and oxygen. So the experimental kerma coefficients for these important nuclides are obtained from the experimental energy-differential cross sections according to the formula [4,5] …”