There are several advantages in using a crystal for stripping of the H- ion to obtain efficient injection of protons into a circular accelerator. First, the stripping efficiency of a crystal is at least as large as for an amorphous foil of the same substance and thickness. Second, the emittance increase imposed by the multiple Coulomb scattering of the protons on subsequent turns is drastically lower by a factor of up to similar or equal to7. Third, the restricted energy loss of the protons is lower by a factor of up to similar or equal to1.5-this, combined with the fact that the thermal conductivity of a single crystal of diamond is much higher than that of the amorphous material, will reduce the effect of heating of the stripping material. In high-power schemes based on amorphous foils heating of the electron stripping material is a limiting factor. Fourth, the reduced total energy loss is accompanied by a smaller energy loss straggling implying a smaller longitudinal emittance. Last, the so-called random orientation of the crystal can provide the option of stripping the H- ions as in an amorphous foil while preserving the advantage of a high thermal conductivity, simply by changing the orientation of the crystal. A simulation using realistic parameters is presented, which reflects the efficient conservation of emittance using a diamond crystal. The phenomenon should in fact be applicable in general for the stripping of H-, although the advantages depend on parameters such as the energy. A reasonable figure of merit is the ratio of the total transverse emittance increase of crystalline and amorphous foils in one turn and in the presented case this is as high as a factor 3.9.

NMR measurements on single crystals of pure $^{13}\mathrm{C}$ diamond are reported. The line shape is very sensitive to the orientation of the external magnetic field relative to the crystallographic axes, typical of dipolar line broadening. With the magnetic field oriented along the [110] direction, the line is broad and flat, whereas a more narrow, Gaussian shape is seen along [001]. For the [111] direction, a spectacular line splitting of 8.5 kHz is observed. For the sample studied, the spin-lattice relaxation time was about 15 s at room temperature and 140 s at 140 K. The spectra are interpreted by a simple model using dipolar interactions.

The descriptions of heavy-ion inelastic scattering given by the folding model and phenomenological potentials require different degrees of deformation of the optical potential. This is because the rule of equal normalised multipole moments of the optical potential and the nucleon density distribution, imposed by the folding model, conflicts with the rule of equal deformation lengths borne out by analyses with Woods-Saxon potentials. It is shown, in an example of inelastic scattering of heavy ions from deformed nuclei in the region of strong Coulomb-nuclear interference, that the double-folding model description of the experimental data is as good as any description with deformed Woods-Saxon potentials. Thus neither of the two different rules for deforming the optical potential is a universal prescription since they only apply to specific classes of potentials.

The fusion cross section of the $^{10}\mathrm{B}$ + $^{14}\mathrm{N}$ system has been measured at five energies covering the range ${{E}_{14}}_{\mathrm{N}}=86\ensuremath{-}180$ MeV. Angular distributions of fusion and direct reaction components for products from $Z=3$ to $Z=11$ have been determined. Hauser-Feshbach calculations of the $Z$ distributions, energies and angular distributions of the evaporation residues are presented and compared to the data. The fusion cross section decreases slowly with increasing energy and reaches a maximum angular momentum of about $21\ifmmode\pm\else\textpm\fi{}1\ensuremath{\hbar}$. The fusion cross section is discussed in terms of entrance channel models and compound nucleus formation and is compared to that of the $^{12}\mathrm{C}$ + $^{12}\mathrm{C}$ system. The experimental total reaction cross sections are in good agreement with optical model calculations with parameters deduced from elastic scattering.NUCLEAR REACTIONS $^{14}\mathrm{N}$ + $^{10}\mathrm{B}$, ${{E}_{14}}_{\mathrm{N}}=86 \mathrm{to} 180$ MeV, measured $\frac{{d}^{2}\ensuremath{\sigma}}{d\ensuremath{\Omega}\mathrm{dE}}$ for reaction products from $Z=3 \mathrm{to} 11$. Extracted ${\ensuremath{\sigma}}_{\mathrm{fusion}}$, ${\ensuremath{\sigma}}_{\mathrm{direct}}$, and ${\ensuremath{\sigma}}_{\mathrm{total}}$.

Axially channeled electrons are captured into bound states of the "atomic-string" potential. When two rows lie in close proximity as in the $〈110〉$ direction of diamond, the potentials overlap, forming a saddle point between the rows. For 4-MeV electrons in the $〈110〉$ diamond potential, the $2p$ level lies above the saddle point, and molecular states are formed. The observation of radiation arising from transitions of these states is reported. Spectral information is used to deduce electron-density enhancement in the C-C bond.

The crystal-blocking lifetime technique (BLT) was used to examine several effects in the in-elastic scattering through 90° of ≈ 5 MeV protons from ≈ 1.5 μm thick germanium crystals to various excited states, using the elastic scattering observed simultaneously as a “promptness” monitor: (a) the enhancement effect an isobaric analog resonance has on the underlying fine-structure states in its vicinity; (b) the effect of different level densities and hence level widths at different excitation energies in different Ge isotopes; (c) the effect on the mean lifetime of the final-state spin in the same isotope; and (d) a slight difference in the mean lifetimes for two different proton groups in the same isotope leading to states of the same spin, a result revealing a possible nuclear (intermediate) structure effect, i.e. one that cannot be explained on the basis of the statistical model. The excitation energies reached in the compound nuclei of arsenic range between 10 and 12 MeV. All results were obtained below the respective lowest neutron thresholds; the resulting lifetimes lie in the range 10−16–10−17 sec, corresponding to mean level widths around 20 eV; this is still considerably less than the estimated mean level spacing, even when the fine structure is enhanced within the analog resonance; i.e. Γ/D ⪡ 1. The actual contact between experiment and calculations based on computer simulations of charged-particle penetration through crystal lattices is made at the level of comparisons of the depths of characteristic blocking dips.

A variable-energy gamma-ray system is described. Monoenergetic gamma radiation undergoing Compton scattering produced this energy variability over a significant range. The parameters of the system are described.Gamma radiation from a ${\mathrm{Co}}^{60}$ source of strength 1200 C was Compton scattered from a copper scatterer. The energy of the scattered radiation varies continuously from 1.33 MeV in the forward direction to 0.21 MeV at a scattering angle of 180\ifmmode^\circ\else\textdegree\fi{}. The rays of mean energy 480 keV, corresponding to a mean scattering angle of 69.5\ifmmode^\circ\else\textdegree\fi{}, were resonantly scattered by lithium. From a self-absorption experiment the mean life of the first excited state of ${\mathrm{Li}}^{7}$ was found to be (1.48\ifmmode\pm\else\textpm\fi{}0.35)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}13}$ sec.

A number of angular distributions of protons from the reaction ${\mathrm{Li}}^{7}(d, p){\mathrm{Li}}^{8}$ have been measured for a range of incident deuteron energies below 2.5 Mev. These agree remarkably well with a simple form of Butler-Born stripping theory, uncorrected for Coulomb and nuclear effects. A description is given for this unusual agreement in terms of the small $Q$ value, -0.188 Mev, for the reaction.A resonance in the proton yield is found at an incident deuteron energy of 1.4 Mev which has not been observed in measurements of the $\ensuremath{\beta}$ yield from this reaction. Angular distributions measured on and around the resonance show no influence of this on the unusually good stripping patterns.

Proton groups from the reactions Li/sup 7/(d,p)Li/sup 8/ and C/sup 12/ (d,p)C/sup 13/ (3.09-Mev state) were studied for a range of deuteron energies between 0.5 and 2.5 Mev using high-resolution magnetic analysis. The examples presented indicate an unusually high degree of agreement between experimental angular distributons and a simple stripping theory uncorrected for Coulomb and other effects. (W.D.M.)

Evaporated natural potassium metal targets were bombarded with protons from a Cockcroft-Walton generator. The excitation function was studied from 0.5 to 1.15 Mev. The gamma rays from a level found in calcium 40 at 9.29 Mev above the ground state were studied with single-crystal spectrometers and with a pair spectrometer. Gamma rays of energy 9.29\ifmmode\pm\else\textpm\fi{}0.005 Mev, 5.93\ifmmode\pm\else\textpm\fi{}0.005 Mev, 5.55\ifmmode\pm\else\textpm\fi{}0.005 Mev, 3.73\ifmmode\pm\else\textpm\fi{}0.005 Mev, and 0.500\ifmmode\pm\else\textpm\fi{}0.005 Mev were found and suggest a decay scheme in agreement with the levels in ${\mathrm{Ca}}^{40}$ found by Braams by inelastic proton scattering.