The (n,n'gamma) reaction at En = 14.1 MeV has been studied for O16 and Ca40. Differential cross sections were obtained for the scattering by the ground states and several excited states. The excitation of the lowest 3- states was quite strong fpr each nuclide. This is evidence that the collective octupole description is valid for these 3- states. The elastic cross sections were successfully fitted using the optical model. The optical parameters which resulted were employed in DWB calculations to predict scattering cross sections for the lowest 3- states. of O16 and Ca40. For these calculations, the 3- states were represented by collective octupole vibrations. The agreement with experiment was good in the case of Ca40 but poor in the case of O16. The latter result may be due to the inadenquacy of the DWB method for such a light nucleus. Energy, yield and angular distribution measurements were made for the deexcitation gamma rays. For O16 the results were used to deduce excitation cross sections which were in good agreement with the neutron data. It was observed that states higher than the first 3- levels in O16 and Ca40 seldom decay by direct ground state transitions but rather by cascade events which proceed throught the first 3- states. This result is in accord with the assumption of a collective vibrational nature for these states if it is assumed that some of the higher states are formed on top of the 3- level.

In the first part of this work the construction of a high precision microscope stage is described with particular reference to a compensating system using two pulleys. The noise measurement of this stage is made by means of an electronic system which measures noise down to a few Angstrom units. The second part is a study of the stars produced by the interaction of 6.2 Bev. protons with emulsion nuclei. The angular distribution of the pions is found in the laboratory system after reconsidering the definition of the shower particles. The results obtained indicate that in the collision of 6.2 Bev. protons with complex nuclei 3 or 4 nucleons of the target nucleus are directly involved in the pion production. The charged pion multiplicity is found to be 2.5 +/- .2 per star. These results are in agreement with those predicted by the tunnel theories.

Part I. An existing Time-of-Flight system was improved so that 14 MeV neutrons, after striking an oxygen target, could be detected with sufficient resolution to indicate whether the state excited was at 6 or 7 MeV. The new data obtained concerning angular distributions was compared with previous data, and agreement was sought with several theoretical models. Part II. Several detection devices, suitable for a spectrometer, which could operate with neutrons up to 14 MeV of energy were tried. One of the devices, a Li6I(Eu) crystal, cooled to the temperature of liquid air, proved quite promising. Once the difficulties of obtaining a good crystal are overcome, it appears that this device is quite suitable for studying neutron induced reactions in shielding materials.

Enriched 58Ni targets were bombarded with H1 + ions of energy varying from 900 to 2000 kev. A 30 cc Ge(Li) detector was used to detect the gamma rays following the radiative proton capture. Nine resonances were studied and the spectra analysed to give gamma ray branching ratios and energy levels in 59Cu. From the decay of the resonance level for Ep = (1423.64 +/- .43) kev and Ep = (1843.45 +/- .56) kev the Q of the reaction was calculated to be (3418.5 +/- 2.4) kev. Partial proton and gamma ray widths were determined by integration of the 1303 kev and 878 kev gamma ray peaks following the beta+ disintegration of 59Cu. A Doppler shift measurement performed on the Ep = 1424 kev resonance level gave a value tau < 2 x 10-15 second.

A flying spot microscope has been designed, constructed and calibrated for studying nuclear events in nuclear emulsions. The instrument has seven major units as follows: (i) Synchronizing Generator, (ii) Flying Spot Scanner, (iii) Optical System, (iv) XY stage, (v) Video Chain, (vi) Monitor for visual presentation, and (vii) a Line Selector for digitization in one direction at the image plane. Detailed descriptions of these units are given. The calibration procedures are outlined and numerical calibrations for the instrument are given.

This work deals with the study of interaction of pions in complex nuclei. The cross sections for inelastic interactions of positive pions with emulsion nuclei have been measured at various pion energies in the (3,3) resonance energy region. The results-have been interpreted in terms of pion-nucleon interaction cross section through isobar formation, using the optical model formalism. Good agreements have been obtained between the experimental and calculated results. The results indicate that the maximum in cross section occurs at about 160 MeV pion incident energy, which is less than the energy at which the (3,3) resonance occurs. This shift in the position of the maximum cross section is attributed to the optical model potential seen by the pion inside the nucleus. Other available experimental data of positive pion interaction cross sections with complex nuclei have been summarized and interpreted successfully by using our model. This model has also been used to obtain the fraction of pions absorbed inside the nucleus in antiproton annihilation. When an antiproton annihilates on a nucleon a number of pions are produced. If, however, the annihilation takes place inside the nucleus, a fraction of pions is absorbed before coming out of the nucleus. The available experimental data on pion multiplicities in T annihilation with hydrogen and emulsion nuclei are compared to obtain the absorption fraction. The results have good agreements with the calculated values in the (3)3) resonance region. The pion-nucleus optical model potential used for our calculation has been obtained on the basis of the theory of Frank-Gammel and Watson in conjunction with the "effective-range" theory of Chew and Low. Many body effects have been taken into account by applying the Pauli exclusion principle to the intermediate state of the nucleon. It has been shown that in the nucleus the peak of the (3,3) resonance in pion-nucleon scattering is considerably reduced and its position shifts towards higher energy. To investigate the mechanism of absorption of pions in complex nuclei, a detailed analysis of the energetic protons produced in the pion induced emulsion stars have been carried out. The stars were produced by (a) direct interaction of 70 MeV positive pions and (b) p¯ annihilation in emulsion. In the latter case, annihilates to produce pions which in turn interact with other nucleons in the nucleus. The absorption of a pion takes place on a pair of nucleons to emit two energetic nucleons. The distributions of energy and opening angles of the energetic proton pairs as well as the energy distribution of the individual energetic protons have been measured. The results are compared with the results obtained from Monte Carlo calculations.

A time of flight system using an associated particle detector was developed for use with DD neutrons of 2.37 MeV. As part of this system a new method of neutron gamma discrimination based on the Owen principle was developed; this method distinguishes 0.5 MeV neutrons from a very wide energy range of gamma rays. This apparatus was then used to measure the angular distributions of the neutrons scattered from the ground state and the 0.845 MeV state of Fe56.

Electron spin resonance (ESR) studies are reported for Cr3+ and VO2+ in AlCl3.6H2O. Electron-nuclear double resonance (ENDOR) studies are reported for the isotope 53Cr 3+ in AlCl3.6H2O. All the microwave measurements were done at X-band microwave frequencies (∼ 9.4 GHZ). The VO2+ study was done at room temperature and it shows that these are two different orientations of the Al3+.6H2O complexes per unit cell. The VO2+.5H2O complexes associated with the two types of Al3+.6H2O complexes are rotated with respect to each other by an angle 33° +/- 3° in the plane perpendicular to the crystal c axis. The Cr3+ ESR measurements were done at four temperatures between room and liquid helium temperature, while the ENDOR of 53Cr3+ was done at liquid helium temperature. The Cr3+ studies show that the sign of the spin Hamiltonian zero-field splitting parameter D is negative, indicating that the Cr3+.6H2O magnetic complexes are trigonally compressed in AlCl3.6H2O. A comparison is made between the spin Hamiltonian parameter for 53Cr3+ impurities in several hydrated crystals and it is found that a purely static crystal field model does not satisfactorily explain the experimental results. When the VO2+. spin Hamiltonian parameters are also included in the comparison it is possible to make conclusions regarding the relative susceptibility of the various Al3+.6H2O complexes to distortion upon impurity doping. In particular it is concluded that the complexes in CsAl alum are more susceptible to distortion than are those in AlCl 3.6H2O.

The electron-nuclear double resonance (ENDOR) spectrum of 57Fe 3+ in the two alums RbA1(SO4)2·12H 20 and RbGa(SO4)2·12H20 is examined at ∼9.4 GHz and 4.2 K. With the magnetic field in a general direction of the crystals, the ENDOR spectra of the four sites in the unit cell of the crystals were observed. A spin Hamiltonian expressed in trigonal form adequately described the observed frequencies of the four sites for the magnetic field in two directions. The hyper-fine parameters were found to be slightly anisotropic. The nuclear spectroscopic splitting factor gI was found to be isotropic within experimental error, with a value of gI = 0.180 +/- 0.004. An additional term of the type S3I was required for a successful fit of the experimental results to the spin Hamiltonian. The parameters are compared with those obtained by others in EPR or ENDOR studies of 57Fe3+ in different crystals systems.

At the present time, the meaning of the cluster model and what is meant by clustering in actual nuclei has not been fully clarified. It is thought that some progress is made here in an understanding of clustering in nuclei. Along with defining the cluster model, the amount of ad hoc involved in the choice of a certain cluster model of a nucleus is given. Also presented here, is a quantitative measure of the amount of clustering occurring in the nucleus. A calculation of this measure of the degree of clustering in the Be 8 nucleus is performed with success. It is demonstrated that Be 8 is slightly ellipsoidal in shape and much less dense than a free alpha particle, The radius of the alpha particles within Be8 is calculated and compared with the radius of a free alpha particle. The separation of the alpha particles is found to be much less than the magnitude of the alpha cluster radius. This investigation also revealed certain new mathematical and physical properties of the cluster model.