Determination of Total Widths and Resonance Energies of the Single-Particle Analog Resonances inBi209

Abstract

Excitation functions for the inelastic scattering of protons from 2C spb have been obtained for incident proton energies from 14 to 18 MeV. Resonances corresponding to the first seven single-neutron isobaric analog states (IAR) of 209 Pb are observed. Many of the inelastic-scattering excitation functions show a resonance at only one of the IAR. These excitation functions were fitted with a five-parameter formula which consists of a resonance amplitude and an energy-independent background amplitude. For some excitation functions, additional resonance amplitudes were included. The analogs of the g 9 /2 (ground-state), i n/ 2(0.79-MeV),j u/2 (1.41-MeV), d 5/2 (1.56-MeV), s 1/2 (2.03-MeV), g 1/2 (2.47-MeV), andrf 3/2 (2.52-MeV) states are found to have total widths of 253±10, 224±20, 201±25, 308±8, 319±15, 288±20, and 279db20 keV, respectively. In respective order, the resonance laboratory energies are 14.918rb0. 006, 15.716db0.010, 16.336 ±0.015, 16.496±0.008, 16.965±0.014, 17.430±0.010, and 17.476±0.010 MeV.

Thei11/2f5/2andi11/2Heusler1, Graw2, Hertenberger3 et al. 2006Phys. Rev. C234431View full textAdd to dashboardCite

“…There are five doublets with a spacing of less than 15 keV among the first 30 states below E x ≈ 4.8 MeV, and the average spacing of the known levels in the region E x ≈ 5.0-6.0 MeV is already about 10 keV. Earlier work from the 1960s [12][13][14][15] improved the energy resolution from 35 to 18 keV. Some data were obtained using a magnetic spectrograph with a resolution of 9-13 keV and photo emulsion plates [7,14], but further improvement of the energy resolution is clearly needed.…”

“…(3)]. Excitation functions of a typical particle-hole configuration are shown at upper left for each IAR [12]. For the two weakest IAR i 11/2 , j 15/2 they are barely visible; therefore they are scaled up by a factor of 10 (thick curves).…”

“…Earlier measurements at backward angles up to = 170 • exist [11][12][13][14][15]31] and are still useful despite lower resolution. Namely IAR-pp angular distributions are symmetric around = 90 • in the absence of direct (p, p ) contributions.…”

“…Using the data and analysis of [12,14] we derive values of R LJ = 7, 12, 12 for LJ = g 9/2 , d 5/2 , s 1/2 IAR, respectively; see Table I. For the doublet d 3/2 + g 7/2 IAR we assume a factor R LJ = 15, but we note that the given equations are valid for isolated IAR only.…”

“…From the observed cross sections, its excitation functions and angular distributions, we obtain quantum numbers and amplitudes of the neutron particle-hole configurations. Early measurements of inelastic proton scattering via IAR [7][8][9][10][11][12][13][14][15] provided examples about the complex mixture of the particle-hole configurations.…”