(p,$gamma$) RESONANCE-CURVE SHAPES AND MEASUREMENTS OF RESONANCE ENERGIES WITH H$sub 1$$sup +$ BEAMS

Journal Article · Wed May 01 04:00:00 EDT 1963 · Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D

DOI:https://doi.org/10.1103/PhysRev.130.1078· OSTI ID:4728848

Bondelid, R O; Butler, J W

During the preparation of a new precise absolute energy scale for nuclear reaction accelerators, some anomalies were observed in the behavior of (p, gamma ) resonances. These observations led to an exhaustive investigation of (p, gamma ) yield-curve shapes and detailed interpretation of these shapes in terms of physically significant quantities such as resonance energy and resonance width. Most of the measurements were made with respect to the 992-kev resonance in the Al/sup 27/(p, gamma ) reaction, but other reactions were also used. A list of the anomalies observed includes (1) the failure of the peaks of thin- target resonance yield curves to be shifted from resonance energy by as much as half the target thickness, (2) the displacement of the midpoint of the rise of thick-target yield curves to bombarding energies below the resonance energy, (3) the overshoot of the yield curve for thick targets forming a hump above the thicktarget plateau, (4) the obtalning of apparently different intrinsic resonance widths for the same resonance and from the same thick target at different times separated by a few weeks, and (5) the obtaining of significantly different thicktarget yield-curve shapes from the same target in two different orientations with respect to the beam. The anomalies are all satisfactorily explained on the basis of fluctuations in energy loss of the bombarding protons as they penetrate the target. The theory used was chiefly developed by Symon. Detailed numerical integrations of the formal yield equation were made, and in most cases very good fits were made with the experimental data. The information gained from this investigation is applied to energy calibrations resulting in precise best values for the following narrow (p, gamma ) resonances: Al/sup 27/ (p, gamma )Si/sup 28/reaction, 991.91 ction in DDT-C/ 0.30 and 1317.19 ction in DDT-C/ 0.40 kev; C/sup 13/(p, gamma )N/sup 14/ reaction, 1747.06 ction in DDT- C/ 0.53 kev; Ni/sup 58/(p , gamma ) ction in DDT-C/ 0.56 kev. The displacement of the midpoint of the rise of a thicktarget yield curve from the resonance energy E/sub r/ as a function of the resonance width GAMMA is discussed, and a typical curve of this relation is shown. The overshoot or hump height for a thick target as a function of GAMMA is also discussed, and a curve is shown. (auth)

• Research Organization: Naval Research Lab., Washington, D.C.
• NSA Number: NSA-17-019349
• OSTI ID: 4728848
• Journal Information: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Journal Name: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D Vol. Vol: 130; ISSN PHRVA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ALUMINUM 27
BEAMS
CARBON 13
COPPER 59
DIFFERENTIAL EQUATIONS
ENERGY
GAMMA RADIATION
HYDROGEN 1
IONS
IRRADIATION
LIFETIME
MEASURED VALUES
NICKEL 58
NITROGEN 14
NUCLEAR REACTIONS
NUMERICALS
PHYSICS
PROTONS
RESONANCE
SILICON 28
TARGETS
THICKNESS
WIDTH