We have observed the production of the $D^0$ meson by neutrinos followed by the decay $D^0\to {K_S}^0+{\pi }^{+}+{\pi }^{-}$. Correcting for detection efficiencies and $K^0$ decay branching ratios, we find that the production of the $D^0$ followed by decay into $K^0{\pi }^{+}{\pi }^{-}$ corresponds to (0.7 ± 0.2)% of all charged-current neutrino interactions.

We have measured residual proton yields from deep-inelastic electron scattering as a function of the fractional longitudinal momentum, $z_p (=\frac{p_l}{p_{lmax}})$, imparted to the proton. We find a peaked distribution in $z_p$ centered near $z_p=-0.25\mathrm{}$.

Calculations based on a two-nucleon ($n-p$) absorption mechanism show that the form factor of the residual nucleus plays an important role in determining the shape of the photoproduction cross section in a wide energy range $60 \mathrm{MeV}<~E_{\gamma }<~300 \mathrm{MeV}$.

We discuss the masses of nuclear bag states containing $3A$ quarks, the decay width of the deuteron bag, $d^{*}$, the appearance of dinucleon bags as resonances in nucleon-nucleon reactions, the inelastic form factor for the reaction $\mathrm{ed}\to e^{\prime }{d}^{*}$ and the differential cross section for $\mathrm{pd}\to p^{\prime }{d}^{*}$. Separation of bag signals from the background from pion production requires the detection of one or more decay nucleons.

By detecting in coincidence the two emitted protons, we have studied the reaction $\mathrm{D}(\gamma ,pp){\pi }^{-}$ in a kinematical region where the pion-nucleon single-rescattering mechanism is dominant. We have also observed the onset of the photoproduction of two pions on one nucleon followed by the reabsorption of one of them by the other nucleon.

I evaluate the contribution, to the cross section for the reaction $\gamma \mathrm{D}\to \mathrm{pp}{\pi }^{-}$, of the mechanism in which one of the two pions created at one nucleon is reabsorbed by the other.

Particle-$\gamma$ coincidence experiments have been performed to study heavy-ion-induced reactions at 6-9 MeV/nucleon which lead to fast $\alpha$ particles. Experimental evidence is presented that the $\alpha$ particles are emitted in a new class of reaction called "massive transfer" which involves fusion of the remaining projectile mass. Such reactions are shown to occur with large cross section. High-spin states in the residual nuclei are populated, but side-feeding $\gamma$-ray intensities are distinctly different from those observed in (HI, $\mathrm{xn}\gamma$) reactions [HI is heavy ion].

The total conversion coefficient, $\alpha$, of the $\gamma$-ray continuum has been determined as a function of $\gamma$-ray energy from 0.5 to 2.5 MeV. The results are consistent with a mixture of $E1\mathrm{}$ and $E2\mathrm{}$ for $E_{\gamma }>~1.0$ MeV, with a smooth increase of the $E1\mathrm{}$ fraction with $E_{\gamma }$ up to ∼1.5 MeV. At lower energy, in the upper half of the yrast region, $\alpha$ shows the expected dominance of $E2\mathrm{}$ radiation, but for the lower half an increasing $M1\mathrm{}$ contribution is found.

I present the first results of a precise measurement of the intense-field Stark effect in highly excited states of atomic hydrogen, a prototype system for experimental and theoretical studies of resonant states in the nonperturbative regime. I show that the quantity $n^{4}F$ (in atomic units), known to be important for field ionization, also governs the divergence properties of the perturbation series for the energy shift.

The deviation of a resistor's $I-V$ curve from linearity as a result of Joule heating and its temperature coefficient of resistivity are shown to be sufficient to predict the low-frequency limiting spectral density of resistance fluctuations caused by spontaneous enthalpy fluctuations. The prediction agrees with previous experiments. Previous predictions that substantially exceeded measured noise in metal film resistors are shown to rely on incorrectly normalized current-jump data.

We have observed 692 events of the type $e^{+}{e}^{-}\to e^{\pm }{X}^{\mp }$ ($X\ne e$) in the center-of-mass energy range $3.1 \mathrm{GeV}<E_{\mathrm{c}.\mathrm{m}.\mathrm{}}<7.4\mathrm{} \mathrm{GeV}$. The observation of events below $D^0{\overline{D}}^0$ threshold clearly precludes their association with charm. The data are well fitted by a pointlike spin-½ $\tau$ lepton with mass ${1782}_{-7\mathrm{}}^{+2\mathrm{}}$ MeV, electronic branching ratio 0.160 ± 0.013, and branching ratio to ≥ 3 charged particles 0.32 ± 0.05.

Analyzing powers were measured for the reactions ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$($p$,$\alpha$)${}_{}{}^{113}{}_{}{}^{}\mathrm{In}$ and ${}_{}{}^{112}{}_{}{}^{}\mathrm{Cd}$($p$,$\alpha$)${}_{}{}^{109}{}_{}{}^{}\mathrm{Ag}$ at 22.0 MeV. A strong $J$ dependence distinguishing between $\frac{1}{2^{-}}$ and $\frac{3}{2^{-}}$ states was observed in both reactions. The analyzing powers are well reproduced by the distorted-wave Born approximation using a triton-cluster form factor.

A model combining pre-equilibrium and compound-nucleus emission is used to explain the observed emission of charged particles following $\mu$ capture from nuclei with $A\gtrsim 20$. The good agreement obtained constitutes additional evidence for a recently proposed distribution of the nucleon momenta in nuclei.

We investigated the electric transition operator in view of existing meson-exchange charge densities. We show that even in the long-wavelength limit the electric dipole operator has important two-body contributions which are not covered by the conventional Siegert operator. These two-body parts are of mixed isospin and lead to a breakdown of the selection rules. The generalization of the Bethe-Levinger sum rule is given. As a numerical application we calculated the forward proton production in $\mathrm{D}(\gamma ,p)n$ where we show the importance of the discussed terms.

Deep inelastic reactions are studied including both particle transfer and excitations of collective surface modes. Detailed results are given for three examples.

Without the imposition of a toroidal magnetic field, a toroidal plasma current is sustained whose maximum current density increases linearly with the applied poloidal surface magnetic field strength. Both plasma compression and heating are observed in the main weak-field region, and average $\beta \approx 6\%$ and energy confinement time $\tau =1\mathrm{}$ msec have been achieved. This concept significantly increases the $\beta$ values and the allowable current in toroidal, Ohmically heated plasmas.

If the branching ratio for $D^0\to K^{-}{\pi }^{+}{\pi }^0$, which currently stands at (12±6)%, remains much larger than 3% in future data, then either the $\Delta T=1\mathrm{}$ rule breaks down, or the final-state $\overline{K}\pi \pi$ contains much structure. The possibility that this structure is due to ${\overline{K}}^{*}$ and $\rho$ resonances is briefly examined.

The collisionless universal instability in slab geometry with a sheared magnetic field is considered. It is shown from the differential eigenvalue equation that no bound growing eigensolutions exist. The method of solution consists of first assuming that exponentially growing eigenmodes exist and then forming quadratic quantities from which a contradiction is obtained. The relation between the eigenmodes and convective modes is discussed.

The rotation of physisorbed monolayers with respect to the substrate was first predicted by Novaco and McTague in the harmonic approximation. An anharmonic theory of this effect is given here. The rotation takes place at the commensurate-incommensurate transition, provided the longitudinal sound velocity of the free adsorbate is more than twice as large as the transverse sound velocity.

We calculate the surface density of acoustic phonons for GaAs(110) and relate it to the Brillouin elasto-optic cross section. A continuum of surfacelike excitations is found in good agreement with the position and the shape of the surface structure observed in the measured Brillouin spectrum. The role played by the optical absorption coefficient in determining different scattering mechanisms is also discussed.