PHYSICS DIVISION PROGRESS REPORT, JANUARY 1 TO MARCH 31, 1962

Technical Report · Wed Oct 31 04:00:00 EST 1962

OSTI ID:4760543

A 9 K two years well-defined high velocity heavy ion beams have received increased attention as tools in nuclear structure studies. ln order to assess the heavy ion energies that may be achieved with a proposed tandem accelerator, it is necessary to know how many electrons can be stripped from energetic heavy ions. For this reason measurements were made of the charge distribution of F/sup 19/, Cl/sup 35/, and Br/sup 79/ ions which were passed through a thin C stripping foil at 10 to 40 Mev. It is found, for example, that at 15 Mev a good yield of Br/sup 79/ ions of charge 13 is obtained. Thus a machine with 15-Mv terminal voltage and one stripping foil would provide a copious beam of 210-Mev Br/sup 79/ ions. By using a second stripping foil, useful beams at energies up to 300 Mev would be obtained. The corresponding maximum energy for Cl is 230 Mev and for F, it is 150 Mev. The Br ions would initiate nuclear reactions with elements up to Xe, and the Cl and F would produce nuclear reactions with all elements. The solar particle events of Nov. 15, 1960, and of July 20, 1961, were further analyzed. The characteristics of both these events strongly support the hypothesis that in planetary space large loops of magnetic flux are dragged out from the vicinity of sunspots by the solar plasma. In the Nov. 12, 1960, event the earth seemed to be initially outside a magnetic bottle formed by such lines of magnetic force at the time of emission of a burst of fast protons from the sunspot, and was subsequently enveloped by the cloud and subjected to the full intensity of the bottled protons. The interpretation of these events with the Deep River neutron monitor observations is now generally accepted as valid. For many years it was believed that the low- lying excited states of a system of aligned magnetic moments (a ferromagnetic or antiferromagnetic crystal) are spin waves, wave-like magnetic disturbances soniewhat similar to the lattice waves in crystals. A few years ago neutron scattering studies gave a direct demonstration of the existence of long wavelength acoustic spin waves in magnetite. Additional measurements demonstrated the existence of short wavelength spin waves, including an optical branch in which magnetic moments on different sublattices move in opposite phases. From the measurements the interactions between the magnetic moments can be deduced. In connection with classical physical situations and standard mathematical functions, problems of computation constantly arise. New computational methods, applicable in such domains of the parameters, have accordingly been developed and tested. In many reactor operation and development problems requiring numerical answers the use of diffusion theory is justified in predominantly scattering media provided it is supplemented by boundary conditions supplied by transport theory. A boundary condition frequently required is that at the interface of the scattering medium with a strong absorber. This can be expressed in terms of the blackness of the absorber, or medium enclosed by the boundary, the fraction, that is, absorbed of all neutrons incident on the boundary. The nature of the boundary condition for unit blackness, that is for a perfect absorber, and for various geometrical forms of the boundary was an early subject of study. Such studies were since extended to other absorbers and have now a considerable development. The ranges of validity of approximations useful under various conditions were examined and computational methods were developed. The shell model of the nucleus is often used to correlate and interpret the experimental data on the lowlying states of nuclei. For example, the low-lying even parity states of nuclei with atomic number in the range 16 < A < 40 were largely explained on the basis of this model with quite general assumptions about the nature of the nuclear forces and the symmetry properties of the states. An attempt is now being made to carry out a similar classificatio of the low-lying odd parity states. In the

• Research Organization: Atomic Energy of Canada Ltd., Chalk River, Ont.
• NSA Number: NSA-16-032176
• OSTI ID: 4760543
• Report Number(s): PR-P-53; AECL-1542
• Country of Publication: Canada
• Language: English

Related Subjects

ABSORPTION
ACCELERATORS
ANTIFERROMAGNETIC MATERIALS
ASTROPHYSICS
ATOMS
BROMINE 79
CARBON
CHLORINE 35
COMPUTERS
CONFINEMENT
CRYSTALS
DIFFUSION
DISTRIBUTION
ELECTRIC CHARGES
ELECTRONS
ELEMENTS
EMISSION
ENERGY LEVELS
ENERGY RANGE
FERROMAGNETIC MATERIALS
FLUORINE 19
FOILS
FREQUENCY
INTERACTIONS
ION BEAMS
IONIZATION
IONS
IRON OXIDES
LATTICES
MAGNETIC FIELDS
MAGNETIC MOMENTS
MAGNETITE
MASS
MEASURED VALUES
MINERALS
NEON 20
NEUTRON DETECTION
NEUTRONS
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
OXYGEN 16
PARITY
PHYSICS
PLASMA
PROTONS
SCATTERING
SPIN
SPIN WAVES
STRIPPING
SUN
SURFACES
TANDEM ACCELERATORS
TRANSPORT