Search

From natSi (e, e′) spectra taken at 90° and 160°, we present evidence for fragmented 6− T=1 strength in 28Si. A narrow peak at 17.35±0.10 MeV excitation is shown to be consistent with 6− T=1 strength.

The charge form factors of 17O and 18O have been measured by electron scattering, and the charge-distribution differences between these nuclei and 16O have been extracted. The spherical part of the 17O distribution is very close to that of 16O while the 18O distribution is substantially different.

New electron scattering data are presented for levels of 154 Gd. The study includes the three lowest-lying 2 + levels at 0.123, 0.816, and 0.996 MeV excitation energies. These data provide a test of the Interacting Boson Approximation (IBA) prediction that three electric quadrupole transition charge densities are clearly dependent. Deviation of the experimental densities from linear dependence is presented and discussed.

High-resolution (e,e′) was used to measure the form factor of the 6−, T=1 resonance in 28Si. The results disagree with previous experimental results and with theoretical calculations. The role of meson-exchange currents in producing the observed quenching of magnetic strength, and the relevance of (e,e′) to other reactions are briefly discussed.

An effective momentum distribution in the region from about 300 to 900 MeV/c has been obtained from recent high-energy 16O(γ, p0) data. The result is compared with two different interpretations of other experimental data and with theoretical momentum distributions.

The high-resolution electron scattering facility at the MIT-Bates accelarator was used to resolve the 4 + 1 4.12 MeV and 2 + 2 4.24 MeV levels in 24 Mg. The respective E2 and E4 Coulomb form factors were measured and compared to form factors calculated theoretically; the 4 + 1 form factor exhibits a momentum-transfer dependence which strongly suggests that K is a good quantum number in 24 Mg.

The spectrum of electrons arising from the decay of the negative mu meson has been determined. The muons are arrested in the gas of a high pressure hydrogen filled diffusion cloud chamber. The momenta of the decay electrons are determined from their curvature in a magnetic field of 7750 gauss. The spectrum of 415 electrons has been analyzed according to the theory of Michel. The shape parameter, {rho}, is found to be 0.64 {plus_minus} .10. The significance of this result in terms of the beta interaction is discussed.

The electromagnetic form factors of the lowest five 2 + and the lowest two 4 + states in 28 Si are measured via high-resolution electron scattering, some for the first time. Comparison with the renormalized shell model calculations of Chung and Wildenthal reveals deficiencies in the shell model description of these states.

A design study has been completed for the RF system of a pulse stretcher ring to be operated in conjunction with the Bates Linear Accelerator (BLA). The 390m circumference ring is to operate from 300 MeV to 1 GeV, with 80 mA injected current and 1 msec extraction time. The stretcher ring is for nuclear physics research and has radiation damping time and quantum lifetime long compared to the extraction time. The special requirements of the RF system have been considered. Dynamic behavior at the fundamental frequency has been investigated by computer simulation. Higher-order mode impedance limitation has been specified by an investigation of transverse multi-bunch multi-turn instabilities.

We are constructing a polarized electron source in order to study parity violation in elastic electron‐carbon scattering at the MIT Bates Linac. The source uses a GaAs photocathode illumiated by light from an infrared krypton ion laser. Our design, which uses a multi‐chamber vacuum system, meets the special requirements for operation at Bates.