Doorway states ins-,p-, andd-wave entrance channels inPb207+nreaction

The ${}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}$+$n$ reaction has been studied by means of high resolution neutron transmission and differential elastic scattering measurement. Information pertaining to resonance parameters ($E_n$, $l$, $J$, and ${\Gamma }_n$) for some 118 resonances in the energy interval from 3 to 485 keV has been obtained. Distributions of neutron strengths have been determined for each value of $J$ that can be formed by $s$-, $p$-, and $d$-wave neutrons interacting with the ${}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}$ ground state ($J^{\pi }=\frac{1}{2^{-}}$). The existence of a doorway state in the $J^{\pi }=1^{-}$, $s$-wave channel at ∼500 keV is confirmed. Evidence is also found for the presence of doorway states in the $p$-wave ($J^{\pi }=1^{+}$) and $d$-wave ($J^{\pi }=1^{-}$) channels. The doorway state in the $p$-wave channel is shown to be correlated with $M1\mathrm{}$ ground-state radiative strength in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. In the energy region above the doorway state, the "average" $p$-wave strength function for forming $1^{+}$ resonances [$S^1\left(1^{+}\right)=(6.8\mathrm{}\pm 0.6)\times {10}^{-5\mathrm{}}$] is found to be equal to the sum of those for forming $0^{+}$ [$S^1\left(0^{+}\right)=(4.2\mathrm{}\pm 1.0)\times {10}^{-5\mathrm{}}$] and $2^{+}$ [$S^1\left(2^{+}\right)=(2.8\mathrm{}\pm 0.4)\times {10}^{-5\mathrm{}}$] resonances in agreement with predictions of the random phase assumption.