The quasistellar neutron spectrum for a thermal energy of $kT=25$ keV that can be produced via the ${}^7$Li($p,n$)${}^7$Be reaction at a proton energy of $E_p=1912$ keV has been measured using the dedicated setup for the definition of neutron fields at Physikalisch-Technische Bundesanstalt Braunschweig. The results confirm previous work with improved accuracy and resolution. Small variations in proton energy leave the spectrum essentially unchanged. This is illustrated by the example of the ($n,\gamma$) cross section of ${}^{197}$Au, where the averaged cross section for the spectrum defined in this work agrees perfectly with the result of a previous measurement.

• Received 30 January 2012

DOI:https://doi.org/10.1103/PhysRevC.85.055809