The magnetic form factor of3He

Realistic momentum-space wave functions cf the three-nucleon bound state are used to calculate the³He magnetic form factor. The contributions of (1236) admixtures to the wave function and of the and pair-current correction are included and lead to encouraging agreement with the available experimental data.Work supported by funds of the Deutsche Forschungsgemeinschaft (DFG) contract Sa 247/3.Submitted to the symposium Mesons and Light Nuclei, Liblice, Czechoslovakia, June 1981.     

Measurement of the elastic magnetic form factor of (3)He at high momentum transfer.

New electron scattering measurements have been made that extend data on the (3)He elastic magnetic form factor up to Q(2) = 42.6 fm(-2). These new data test theoretical conjectures regarding non-nucleonic effects in the three-body system. The very small cross sections, as low as 10(-40) cm(2)/sr, required the use of a high-pressure cryogenic gas target and a detector system with excellent background rejection capability. No existing theoretical calculation satisfactorily accounts for all the available data.     

Field-induced magnetic form factor of lutetium

The conduction electron field-induced magnetic form factor of Lu, a rare earth metal with a closed 4f shell, has been measured using the polarized neutron technique. The measurements demonstrate that the conduction electron density is more spatially extended than in the free atom. The experimental results are in good agreement with band calculations of the $\text{spin}$ magnetic form factor.     

The structure of He and the neutron electric form factor from polarization observables

As there are no free neutron targets one has to resort to the nuclear targets deuterium or helium. In order to reduce nuclear effects blurring the information on nuclear form factors the technique of double polarization experiments had been developed. Recent experiments at MAMI measuring the electric form factor of the neutron are discussed. In addition, other single and double nucleon knockout experiments are described which support the buildup of a consistent interpretation of nuclear structure in ³He.     

Self-consistent center-of-mass correction and the charge form factor of He

The Hartree-Fock approximation is used for ⁴He in the case of Lipkin's Hamiltonian with several nuclear forces. The self-consistent solution practically coincides with the one obtained in the usual HF method applied to the intrinsic Hamiltonian; however, the center of mass is now in its ground state, and its motion is fairly separated in the ground state function of the nucleus. An unambiguous comparison between experimental and theoretical charge form factor is done. The discrepancies cannot be interpreted as due to spurious c.m. effects.     

Experimental magnetic form factor of platinum metal

The induced magnetic form factor of paramagnetic platinum was measured in an external field of 73 kOe at a temperature of 78 K. The data obtained for the six innermost Bragg reflections show that the spherically average magnetization density is in excellent agreement with that calculated by Watson-Yang. Freeman and Koelling. The result confirms the reliability of the present day band calculations, as well as assuring that the nontrivial orbital contribution to the form factor (g = 2.61) has been handled properly. The asphericity of the magnetization was more poorly determined, yielding at t_2g population of 70 ± 17%, to be compared with a calculated value of 93%. An attempt at a more direct determination of the role of the orbital contribution is described.     

The six-quark-admixture in the form factor of the3He at large transfer momenta

Elastic form factor of the³He nucleus is analysed with the use of Gaussian-type and realistic nuclear wave functions with a contribution of six-quark admixtures taken into account. The latter has been chosen so as to describe the data of analysis of cumulative and other processes and it amounts to about 8%. It is shown that unlike the deuteron form factor for³He the quark-nucleon interference is essential. The six-quark admixture does not remove the second minimum in the form factor of³He as a three-nucleon system atq ²~50 fm^?2. The comparison with other theoretical models and available experimental data is performed.     

Neutron magnetic form factor in strongly correlated materials

We introduce a formalism to compute the neutron magnetic form factor FM(q) within a first-principles density functional theory and dynamical mean field theory. The approach treats spin and orbital interactions on the same footing and reduces to earlier methods in the fully localized or the fully itinerant limit. We test the method on various actinides of current interest NpCoGa5, PuSb and PuCoGa5, and we show that PuCoGa5 is in mixed valent state, which naturally explains the measured magnetic form factor.     

Transverse asymmetry AT' from the quasielastic 3He(e,e') process and the neutron magnetic form factor

We have measured the transverse asymmetry A(T') in 3He(e,e(')) quasielastic scattering in Hall A at Jefferson Laboratory with high precision for Q2 values from 0.1 to 0.6 (GeV/c)(2). The neutron magnetic form factor G(n)(M) was extracted based on Faddeev calculations for Q2 = 0.1 and 0.2 (GeV/c)(2) with an experimental uncertainty of less than 2%.     

Exchange magnetic moment form factor of the three-nucleon system

The exchange magnetic moment form factor of ³H and ³He is derived from experiment, regarding the D state probability P_D as free parameter. The isoscalar part is roughly constant. The rms radius corresponding to the isovector part increases as P_D increases.     

Current conservation, meson-exchange currents, and magnetic form factors of He and H

The effect of the requirement of current conservation for meson-exchange currents containing the πNN form factor is investigated for the magnetic form factors of ³He and ³H. The effect is substantial for the pionic current contribution but is small for the total contribution to the momentum transfer, Q 5 fm⁻¹.     

Transverse asymmetry of $^3\!\stackrel{\rightarrow}{\rm He}$ and the magnetic form factor of the neutron

Multi-nucleon transfer reactions in ⁴⁰Ca + ²⁰⁸Pb have been studied at several bombarding energies close to the Coulomb barrier. Light reaction products have been identified in mass and charge with a time-of-flight spectrometer. The energy spectra of the inclusive two-neutron pick-up channel show a population in a narrow region of excitation energies which corresponds to the predicted energy of pairing-vibration states in ⁴²Ca.Received: 30 September 2003, Revised: 9 December 2003, Published online: 13 July 2004PACS: 25.70.Hi Transfer reactions - 24.10.-i Nuclear reaction models and methods - 21.60.Cs Shell model - 21.10.Pc Single-particle levels and strength functionsA.M. Vinodkumar: Present address: Tokyo Institute of Technology, Japan.     

Some remarks on the charge form factor of He and the center-of-mass motion spuriousity

It is shown that the various single-particle wave functions used to reproduce the charge form factor of ⁴He nucleus contain a large amount of center-of-mass motion spuriousity, so that the good fit to the experimental data obtained with these wave functions is only due to the way the center-of-mass motion coordinate was removed rather than to the characteristics of the model.     

Influence of crystals fields on the magnetic form factor of samarium

It is calculated that crstal fields, with inclusion of mixing of higher multiplets into the ground $\text{J =}\text{5}\text{2}$ state, have a substantial effect on the magnetic form factor of Sm³⁺. From the neutron diffraction data obtained by Koehler and Moon for the cubic site in Sm metal it follows that the quartet Γ₈ is lowest, with the sixth-order crystalline field parameter A₆〈ritr⁶〉 positive. The conduction electron moment residing on Sm is estimated to be of the order of 0.4 μ_B.     

Induced neutron magnetic form factor of LaSn3

Polarized neutron scattering techniques have been used to study the spatial distribution of the magnetization induced in a single crystal of LaSn₃ by a magnetic field of 42.5 kG at 100 K. We find that the magnetic form factor decreases very rapidly with increasing scattering angle, and bears no resemblance to the spin or orbital free-atom magnetic form factor. The experimental results are in reasonable agreement with band theoretical calculations of the spin magnetic form factor of LaSn₃. We conclude that (a) the spin part is the dominant contribution to the bulk susceptibility of LaSn₃ and (b) there is a substantial amount of Sn-5p electronic character in the wavefunctions near the Fermi level.