EXPERIMENTAL MEASUREMENT AND STRIPPING ANALYSIS OF Be$sup 9$(Li$sup 6$,/cap alpha/)B$sup 11$ ANGULAR DISTRIBUTIONS

Journal Article · Thu Feb 01 04:00:00 EST 1962 · Dissertation Abstr.

OSTI ID:4823226

Leigh, J J

Differential cross sections of the Be/sup 9/ (Li/sup 6, alpha )Bt/sup 11/ reactio n were measured as a function of bombarding energy and scattering angle. The alpha particles leaving the B/sup 11/ in the ground state, alpha /sub 0/, in the first excited state, as, and in the second and third excited states, alpha /sub 2/ + alpha /sub 3/, weere observed at 10 deg intervals from 10 to 160 deg (lab system) at Li/sup 6/ energies of 3.00, 3.25, and 3.50 Mev, and at 20, 60, 90, 120, and 160 deg (center of mass system for alpha /sub O/) at energies of 2.00, 2.50, 3.75, and 4.00 Mev. Detection of the alpha particles in the presence of the products of other reactions induced by the bombardment of Be/sup 9/ with Li/sup 6/ was facilitated by the use of a particle identification incorporating a dE/dx and E counter telescopc. The angular distributions of the alpha /sub O/ and alpha /sub 1/ groups were asymmetric about 90 deg cm. Relative maxima occurred at both large and small scattering angles for each of the alpha -particle groups, the yields at large angles being comparable to those at small angles. Relative maxima occurred also at approximately 110 deg center of mass system for alpha /sub O/ and at approximately 80 deg for alpha /sub 1/. In all cases the angular distributions varied only slowly with bombarding energy while the yield at each angle increased monotoni-cally with increasing energy. In going from 3.00 to 3.50 Mev the total cross sections increased by a factor of approximately two. The total cross sections at 3.50 Mev were 1.10 mb for alpha / sub 0/, 0.74 mb for alpha /sub 1/, and 2.76 mb for alpha /sub 2/ + alpha /sub 3/. The uncertainty in the absolute values of the cross sections was approximately 40%, but the relative values were determined to better than 10%. An analysis of the angular distributions was carried out using an elementary form of stripping theory, and is given in detail. Both the normal stripping mode and that exchange mode commonly called heavy-particle stripping'' were incorporated in the analysis. Coulomb effects and compound nucleus contributions were not included. The model assumed that the Li/sup 6/ and Be/sup 9/ nuclei may be represented by the two-cluster configurations alpha particle plus deuteron' and alpha particle plus He/sup 5/'' respectively. The internal structure of the clusters was ignored, but their spins and parities were recognized. The angular distribution calculated for the alpha /sub 1/ group at a bombarding energy of 3.25 Mev provided a satisfactory fit to the experimental results. The theoretical angular distribution for alpha /sub 0/ was less successful but did show the principle features of the experimentally observed angular distribution. A discussion of several of the approximations made in the analysis is included. It was concluded that the reaction mechanism is primarily one of stripping.

• Research Organization: Univ. of Minnesota, Minneapolis
• NSA Number: NSA-16-023034
• OSTI ID: 4823226
• Journal Information: Dissertation Abstr., Journal Name: Dissertation Abstr. Vol. Vol: 22
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ALPHA DETECTION
ALPHA PARTICLES
ANGULAR DISTRIBUTION
BERYLLIUM 9
BORON 11
CROSS SECTIONS
ENERGY
ENERGY LEVELS
ENERGY RANGE
EXCITATION
ION BEAMS
IRRADIATION
LITHIUM 6
MEASURED VALUES
NUCLEAR MODELS
NUCLEAR REACTIONS
PHYSICS
REACTION KINETICS
SCATTERING
STRIPPING