MEASUREMENTS OF THE ENERGIES AND WIDTHS OF CERTAIN NARROW RESONANCES

Technical Report · Fri Oct 31 04:00:00 EST 1958

OSTI ID:4305699

Bondelid, R O; Kennedy, C A

An electrostatic analyzer with a radius of curvature of 2 meters and a deflection angle of 90 deg was constructed, installed, and evaluated. It is used in conjunction with the U. S. Naval Research Laboratory large Van de Graaff to provide a positive ion beam whose energy is precisely known and highly resolved. The absolute energy calibration is believed to be accurate to plus or minus 0.05%, and the inherent energy resolution is accurately 0.01% per 0.010 in. of input slit separation. The analyzer was used to determine the bombarding energies of several (p, gamma ) resonances and (p,n) thresholds in the energy range from 300 kev to slightly over 3 Mev. It has also been used to determine the widths of some very narrow (p, gamma ) resonances. The results from the absolute determination of bombarding energy are: Al/sup 27/(p, gamma )Si/sup 28/ , 992.4 plus or minus 0.5 kev; C/sup 13/(p, gamma )N/sup 14/, 1747.6 plus or minus 0.9 kev; Li/sup 7/(p,n)Be/sup 7/, 1881.2 plus or minus 0.9 kev; C/sup 13/ (p,n)Ni/sup 3/, 3237.2 PP 1.6 kev; Ni/sup 56/(p, gamma )Cu/sup 59/, 1424.1 plus or minus 0.7 kev; Ni/sup 58/(p, gamma ) Cu/sup 5 1843.7 plus or minus 0.9 kev; F/sup 19/(p, alpha gamma )O/sup 16/, 340.5 plus or minus 0.3 kev; F/sup 19/(p alpha )O/sup 16/, 483.6 plus or minus 0.3 kev; F/sup 19/ (p, alpha , gamma )O/ sup 16/, 872 .4 plus or minus 0.4 kev. The measurements of the widths of narrow (p, gamma ) resonances are complicated by the Doppler broadening introduced by the thermal motion of the target nuclei. The resonances that have been examined are a narrow resonance in the Al/sup 27/(p, gamma )Si/sup 28/ reaction, two in the Ni/sup 58/(p, gamma )Cu/sup 59/ reaction, and one in the C/ sup 13/(p, gamma )N/sup 14/ r eaction. Preliminary data on all of these resonances indicate they are of the order of 100 ev full width at half maximum, or less. In addition to the above results, a curious behavior of the mass-2 proton beam was observed. It is found that the mid-points of the thicktarget mass-2 yield curves (obtained in (p, gamma ) reactions) appear at energies lower than those predicted from the mass-1 results. It is thought at the present time that this behavior is related to stopping power in the target. When using very thin targets, of the order of 300 ev thick, the energy discrepancy between thae mass-1 and mass-2 proton beam disappeara. (auth)

• Research Organization: Naval Research Lab., Washington, D.C.
• NSA Number: NSA-12-014973
• OSTI ID: 4305699
• Report Number(s): A/CONF.15/P/675
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ABSORPTION
ALPHA PARTICLES
ALUMINUM 27
BERYLLIUM 7
CARBON 13
COPPER 59
ELECTROSTATICS
ENERGY
ENERGY LEVELS
ENERGY RANGE
ERRORS
FLUORINE 19
GAMMA RADIATION
ION BEAMS
KEV RANGE
LIFETIME
LITHIUM 7
MEASURED VALUES
MEV RANGE
NEUTRONS
NICKEL 58
NITROGEN 13
NITROGEN 14
NUCLEAR REACTIONS
OXYGEN 16
PHYSICS
PROTON BEAMS
RESOLUTION
RESONANCE
SILICON 28
STANDARDS
TARGETS
VAN DE GRAAFF ACCELERATORS
WIDTH