A STUDY OF THE REACTIONS, Be$sup 9$(He$sup 3$,n)C$sup 11$,Li$sup 7$(He$sup 3$,N)B$sup 9$ AND C$sup 13$(He$sup 3$,n)O$sup 15$, BY TIME-OF-FLIGHT TECHNIQUES

Technical Report · Wed Feb 01 00:00:00 EST 1961

OSTI ID:4813996

Duggan, J L

Thesis submitted to Louisiana State Univ., Baton Rouge. Angular distributions and excitation functions were - measured for the reactions Be/sup 9/ (He/sup 3/,n)C/sup 11/, (He/sup 3/, n) Be/sup 9/ and Cd/sup 13/(He/sup 3/,n)O/sup 15/, by time-of-flight techniwues. Distorted and plane wave stripping calculations were made in an attempt to fit the measured angular distributions. ln the distorted wave calculations, the distortion is introduced by scattering from both the Coulomb field and the nuclear optical potential. The calculations show that the distorted wave angular distributions can be made to fit the data while the plane wave calculations fail except for those angular distributions which are peaked strongly in the forward direction. For the Be/sup 9/(He/sup 3/ ,n)C/sup 15/ reaction resolved neutron groups were seen for the ground state and the flrst four excited states (1.99 4.26 4.75 and 6.50 Mev) in C/sup 11/ Excitation functions were measured at 0 and 90 deg for He/sup 3/ energies from 0.5 to 2.7 Mev and angular distributions measured at 2.l Mev. From the distorted wave calculations, the following spin and parity assignments were made; n/sub 0/ (1/2 /sup -/ yields 7/2/sup -/)n/sub 1/(1/2/sup -/ yields 7/2 /sup -/ ), n/.sub 2/(*1/2 /sup -/ yields 7/2 /sup -/ annd n/sub 4/ (3/2/sup -/). For the Li/sup 7/(He/sup 3/,n)B/sup 9/ reaction, neutrons from the ground state were clearly resolved from the unresolved second and third excited states. An excitation function was measured from 0.5 to 2.7 Mev at 0 deg and an angular distribution was taken at 2.1 Mev for the ground state group. Distorted wave calculations give a spin and parity assignment of resolved neutron groups were seen for the ground state and third excited state (6.15 Mev) in O.sup 15/. Excitation functions were measured from 1 to 2.7 Mev at 0 and 90 deg . The most outstanding feature of the excitation function is the resonance at a He/sup 3/ center of mass energy of l.55 Mev. This resonance corresponds to a new state in O/sup 16/ at an excitation of 24.04 Mev. This state has a laboratory width of plus or minus 100 kev. Angular distributions were measured for the ground and third excited states at 2.66 Mev. From the distorted wave calculations, the following spin and parity assignments were made; n/sub 0/(1/2/sup -/) and n/sub 3/ (5/2 /sup +/ yields 7/2 /sup +/. In a summary it might be said that the angular distributions from the (He/sup 3/,n) reactions studied, though complex in nature, can be fitted with distorted wave calculations, even at low energies. Furthermore it appears that the (He/sup 3/,n) reactions can be used to make spin and parity assignments to many of the proton-rich nuclides which are virtually inaccessible by other reactions. (auth)

• Research Organization: Oak Ridge National Lab., Tenn.
• DOE Contract Number: W-7405-ENG-26
• NSA Number: NSA-16-009439
• OSTI ID: 4813996
• Report Number(s): TID-14822
• Resource Relation: Other Information: Orig. Receipt Date: 31-DEC-62
• Country of Publication: United States
• Language: English

Related Subjects

PHYSICS
ANGULAR DISTRIBUTION
BEAMS
BERYLLIUM 9
BORON 9
CARBON 11
CARBON 13
CONFIGURATION
CROSS SECTIONS
DWBA APPROXIMATION
ELECTRIC FIELDS
ENERGY LEVELS
ENERGY RANGE
EXCITATION
HELIUM 3
ISOTOPES
LIFETIME
LITHIUM 7
MEASURED VALUES
MEV RANGE
NEUTRON DETECTION
NEUTRONS
NUCLEAR MODELS
NUCLEAR REACTIONS
NUMERICALS
OPTICAL MODEL
OXYGEN 15
OXYGEN 16
PARITY
PROTONS
REACTION KINETICS
RESOLUTION
RESONANCE
SCATTERING
SPIN
STRIPPING
TIME OF FLIGHT METHOD