Experimental double-differential cross sections (d 2 σ/d d E)for fast neutron-induced production of proton, deuteron, triton, and alpha particle in carbon are reported at several incident neutron energies between 25 and 75 MeV. Angular distributions were measured in the laboratory angular range of 20 • to 160 • . Reliable extrapolated spectra are obtained at very forward (2.5 • and 10 • ) and very backward (170 • and 177.5 • ) angles. Based on these experimental data, energy differential (dσ/d E), angle differential (dσ/d ), and total cross sections (σ T ) are reported for each detected particle. C
INTRODUCTIONDue to obvious experimental difficulties, measurements of charged particle production in fast (20 to 80 MeV) neutroninduced reactions are rather scarce. This type of data offers an important experimental base both for fundamental research and for many important applications. 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.Applications are particularly important in the case of light target nuclei such as carbon and oxygen. Essential information can be obtained for use in neutron dosimetry and radiobiology. A detailed knowledge of cross sections makes it possible to evaluate the contribution to charged particle production of a given element as a constituent of human tissue [1,2] in clinical applications.With the advent of the new accelerator-driven technologies, knowledge of neutron-induced reactions above 20 MeV may also play an imporant role in projects such as the transmutation of radioactive waste or alternative nuclear energy production.
Experimental MethodsExperimental data were obtained at the fast neutron facility of the Louvain-la-Neuve cyclotron, CYCLONE. An accelerated incident proton beam is focused on a 3-mm-thick natural lithium target. With a beam current of 10 −5 A, about 10 6 neutrons/s are available at the location of our reaction chamber (about 3.3 m downstream of the lithium target). The resulting neutron energy spectrum at 0 • consists of a welldefined peak (2 MeV full-width-at-half-maximum) containing about 50% of the neutrons, plus a flat continuum of low energy neutrons (inset in Fig. 1). In the main neutron peak there are about 10 times more neutrons/MeV than in the low neutron energy continuum [3][4][5].The measurements were done with an elemental carbon target (5 × 5 cm 2 surface and 1 mm thick). Four charged particle detector telescopes were used simultaneously. Each of them consists of a E detector (NE102 plastic scintillator) and an E detector (CsI(Tl) crystal). The E detector can stop up to 80 MeV protons. A coincidence is required between E and E detectors in order to suppress an important part of the background present in such type of experiments [6,7]. The collimation system of each charged particle detector telescope had an angular opening between 2 • and 3 • .Protons and deuterons recoiling from, respectively, a polypropylene and a deuterated polypropylene targ...