A 180° magnetic spectrometer has been employed to measure the energy of several neutron thresholds and $\gamma$-ray resonances, as well as the energy of the alpha particles emitted by ${\mathrm{Po}}^{210}$. The primary reason for performing these experiments was to obtain a set of energy standards with consistent experimental techniques for all the measurements. The neutron thresholds studied were ${\mathrm{Li}}^7(p, n){\mathrm{Be}}^7$, ${\mathrm{B}}^{11}(p, n){\mathrm{C}}^{11}$, ${\mathrm{C}}^{13}(p, n){\mathrm{N}}^{13}$, and ${\mathrm{F}}^{19}(p, n){\mathrm{Ne}}^{19}$. The $\gamma$-ray resonances at 872 kev in ${\mathrm{F}}^{19}(p, \alpha \gamma ){\mathrm{O}}^{16}$ and at 992 kev in ${\mathrm{Al}}^{27}(p, \gamma ){\mathrm{Si}}^{28}$ were observed. The same instrument used to make the energy measurements for these experiments was also employed to determine the energy of the alpha particles emitted by ${\mathrm{Po}}^{210}$.

• Received 4 May 1961

DOI:https://doi.org/10.1103/PhysRev.123.2100