Electron Scattering from the Ground-State Magnetization Distribution ofO17

Abstract

Elastic electron scattering has been used to determine the transverse form factor of the ^^O ground state in the effective momentum-transfer range 0.55 =s^e^ 2.8 fm"^ The data show considerable deviation from single-particle predictions; in particular, a sizable suppression of the MS and an enhancement of the high-^ side of the M5. Recent shell-model, core-polarization, and meson-exchange calculations are not adequate to explain these effects ,We report here the first measurements of elastic electron scattering from the magnetization density of ^'^O. The static magnetic dipole moment (-1.894 nm)^ being very close to the Schmidt limit (-1.913 nm) has been viewed as strong evidence for the single-particle nature of this nucleus. In addition, the spectroscopic factor for the ^5/2 single-particle component of the ground state as determined by {d,p) reactions is about 0,9.^ However, the existence of a sizable quadrupole moment (-2.562 ^-fm^)^ for the ground state of ^"^O and the large E2 strengths connecting the ground state to the f"" (0.871 MeV) and f-" (5.083 MeV) states indicate a limit to the usefulness of the extreme single-particle model for this nucleus. These effects can be viewed as due to the nonspherical structure of the ^^O core and its polarization by the odd neutron. Under these circumstances, the ^^O core is expected to in-fluence the magnetization of ^'^O, Electron scattering determines the spatial distribution of the magnetization density and hence provides a severe test of our understanding of the structure of The data were collected at the Massachusetts Institute of Technology-Bates Linear Accelerator using the high-resolution energy-loss spectrometer system.2 Scattered-electron spectra were measured at three scattering angles, 90°, 160°,3 and 180°.^ The three ^'O targets used were isotopically enriched BeG foils manufactured at Lawrence Livermore Laboratory.^ The ^'O isotopic enrichments ranged from about 20 to 85%, Target thicknesses ranged from about 20 to 40 mg/cm^. Normalization for most of the ^""0 data at each energy was relative to ^^O. For the two highest energy points at 160°, where the ^^O cross section was prohibitively small, normalization

Elastic magnetic form factors of exotic nuclei

“…The valence rms radius of 17 O deduced from the best fit of the overall spectroscopic factors α , L s to the magnetic electron scattering data taken from Ref. [43] is 3.35 ± 0.03 fm [41], which is very close to the value 3.36 fm of Ref. [40].…”

“…[46]. The agreement of the [40,43] and [46,47], respectively. rms radii and spectroscopic factors in the RMF theory with the experimental data and other theoretical ones implies the validity of the RMF theory in reproducing the magnetic form factor.…”

“…In this figure, the experimental form factors of 17 O and 41 Ca are taken from Refs. [40,43] and [46,47], respectively. One can see that the theoretical form factors of 17 O and 41 Ca with the spectroscopic factors agree very well with the experimental data in low and medium q region, but in high-q region the theoretical form factors still fall more deeply than the experimental data.…”

Magnetic structure ofO17at high momentum

“…8 This experiment was an extension of a previous experiment done at the same laboratory, but at lower momentum transfers, by Hynes et al 6 Forward-angle measurements were made with use of the targets of Ref.…”

Transverse response of bound single-nucleon Dirac-4 spinors of spin-orbit partners to elastic electron scattering

“…Elastic magnetic scattering of high energy electrons pro vides an excellent way to explore the motions of the nucleons in nuclei, in particular those of the nucleons in the outermost nuclear shells [1][2][3][4][5][6][7][8][9][10][11], The most important observables in elastic magnetic electron-nucleus scattering are the nuclear magnetic form factors of nuclei. According to the models used, there can be a couple of different methods to calculate the form factors [1][2][3][4][5][11][12][13][14][15][16], and each method has its own advantage in revealing the relation between the model and the experimental data.…”