Neutron Spectra fromLi7(d,n)Be8andF19(d,n)Ne20for 1.98-MeV Deuterons

The neutron spectrum from ${\mathrm{Li}}^7\mathrm{}(d,n)\mathrm{}{\mathrm{Be}}^8$ was studied at 120° with respect to the beam of deuterons incident on a lithium metal target. The average deuteron energy in the target was 1.98 MeV. Up to an excitation of 9 MeV in ${\mathrm{Be}}^8$, only the ground state and the first excited state are observed. The neutron group to the excited state has a peak corresponding to 3.1±0.1-MeV excitation in ${\mathrm{Be}}^8$ and a width of 1.75±0.1 MeV in the center-of-mass system; however, the interpretation of these numbers in terms of the level parameters is obscured by the presence of a continuum from three-body decay. The relative differential cross section for the neutron groups leaving ${\mathrm{Be}}^8$ in the ground state and in the first excited state was measured from 0 to 135° and normalized to an absolute value at 0° measured with a LiF target. The cross section for the production of ${\mathrm{Be}}^8$ in the first excited state has some uncertainty because of the contribution from the competing three-body breakup of the compound system. Cross sections at 0° for ${\mathrm{F}}^{19}\mathrm{}(d,n)\mathrm{}{\mathrm{Ne}}^{20}$ are also given for reactions leaving ${\mathrm{Ne}}^{20}$ in the ground state and first excited state.