B. Frois

Deuteron A(Q2) structure function and the neutron electric form factor

We present new measurements of the deuteron A(Q2) structure function in the momentum transfer region between 1 and 18 fm−2. The accuracy of the data ranges from 2 % to 6 %. We investigate the sensitivity of A(Q2) to the nucleon-nucleon interaction and to the neutron electric form factor GEn. Our analysis shows that below 20 fm−2 GEn can be inferred from these data with a significantly improved accuracy. The model dependence of this analysis is discussed.

Measurement of the Neutral Weak Form Factors of the Proton

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The kinematic point [{l_angle}{theta}{sub lab }{r_angle}=12.3{degree} and {l_angle}Q{sup 2}{r_angle}=0.48 (GeV /c){sup 2} ] is chosen to provide sensitivity, at a level that is of theoretical interest, to the strange electric form factor G{sup s}{sub E} . The result, A={minus}14.5{plus_minus}2.2 ppm , is consistent with the electroweak standard model and no additional contributions from strange quarks. In particular, the measurement implies G{sup s}{sub E}+0.39G{sup s}{sub M}=0.023 {plus_minus}0.034(stat){plus_minus}0.022( syst){plus_minus}0.026({delta}G{sup n}{sub E}) , where the last uncertainty arises from the estimated uncertainty in the neutron electric form factor. {copyright} {ital 1999} {ital The American Physical Society}

3H and 3He electromagnetic form factors

Abstract We report the results of three experiments on elastic electron scattering from 3 H and 3 He. A detailed description of the experiments and the data obtained is given. We have performed a combined analysis of the world data on 3 H and 3 He. This analysis gives a complete experimental information on the trinucleon electromagnetic form factors up to q 2 = 30 fm −2 , and also provides a separation into the isoscalar and isovector form factors. The results are compared to selected calculations that include nucleonic and mesonic degrees of freedom.

CHARGE DENSITY OF 40Ca

A large number of theoretical calculations [1-8] are available for the 40Ca ground-state wavefunction. This particular attention paid to 40Ca results from the fact that it is the heaviest N=Z magic nucleus. HartreeFock (HF) calculations yield quite similar results for the density in the nuclear surface region, mainly because many of the effective nucleon-nucleon forces used have been adjusted to fit the nuclear rms-radii. Consequently, calculations differ mainly at small radii, by different amounts of structure in the charge density p (r). A number of possible physical mechanisms that influence this fine structure have been discussed in the literature [9-14].

Radial Distribution of Valence Neutrons from Elastic Electron Scattering

Cross sections for elastic scattering of 175--300-MeV electrons by the nuclear magnetization current density of /sup 87/Sr have been measured. The results are used to determine the shape of the radial wave function of the valence neutron shell. The experiment yields a rms radius of 1g/sub 9///sub 2/ neutrons that is 0.31 +- 0.04 fm smaller than predicted by density-dependent Hartree-Fock theory.

On the radial distribution of the 1f72 proton orbit

Abstract Cross sections for magnetic elastic electron scattering of high multipolarity from 51 V and 59 Co have been measured. They are interpreted in terms of the rms radius of the 1f 7 2 proton orbit. The results for 51 V and 59 Co 1f 7 2 rms radii are smaller by 3% and 9%, respectively, than predicted by the Hartree-Fock-Bogoliubov theory.

A precise determination of the 3s proton orbit

Abstract Elastic electron scattering cross sections have been measured for 205 Tl and 206 Pb at an incident energy of 502 MeV, covering a momentum transfer range from 1.4 to 3.2 fm −1 . The charge density difference of the two isotones is accurately determined. We show that the shape of the 3s proton orbit can be extracted from this difference without ambiguity. The experimental shape is compared to mean field theory predictions.

The magnetic form factor of 51V at very high momentum transfer

Abstract The magnetic form factor of the 51 V nucleus has been measured between 3 and 4 fm −1 . These new data show a clear evidence for the diffraction structure of the M7 magnetic multipole. The data are compared to Hartree-Fock results including meson exchange currents and core polarization effects.

Elastic electron scattering from the magnetization distribution of 4193Nb

Abstract Cross sections of elastic magnetic electron scattering from 41 93 Nb have been obtained at momentum transfers from 1.7 to 2.5 fm −1 . The observed deviation of the dominant M9 amplitude from the 1 g 9 2 single-proton value can be explained by large-space shell model calculations.

Radial distribution of the 1f12 neutron orbit

Abstract The cross section for elastic scattering of electrons by the 49Ti magnetization distribution has been measured and interpreted in terms of the radial distribution of the valence neutron. The difference between 1 f 7 2 neutron and proton radii is determined. The effects of meson exchange currents and core polarization are investigated.