The differential cross section for the elastic scattering of protons by ${\mathrm{F}}^{19}$ has been measured for proton energies from 550 to 1800 kev at center-of-mass angles of 90, 125.3, and 159.8 degrees and for proton energies from 1300 to 1500 kev at 53.2, 60, 70, 80, 100, 110, and 136 degrees. Marked scattering anomalies were observed for proton energies near 669 ($1^{+}$), 843 ($0^{+}$), 873 ($2^{-}$), 935 ($1^{+}$), 1346 ($2^{-}$), 1372 ($2^{-}$), 1422 ($1^{+}$), and 1700 kev. The indicated spin and parity assignments for the corresponding levels in ${\mathrm{Ne}}^{20}$ are required by the results of this experiment or are consistent with them. Observations of the elastic scattering have also been made in the regions of 340 and 480 kev at 159.8 degrees, and no anomaly was observed in either case. The ambiguity in the choice of $\frac{{\Gamma }_p}{\Gamma }$ has been resolved for several of the ${\mathrm{Ne}}^{20}$ levels. An approximate method of correcting the observed cross sections for the effects of finite energy resolution has been developed, and the relative stopping cross section for protons in lithium fluoride has been measured for proton energies from 400 to 1600 kev.

• Received 21 March 1955

DOI:https://doi.org/10.1103/PhysRev.99.138