EXCITATION FUNCTION FOR THE C$sup 12$$($$pi$$sup -$$,$$pi$$sup -$n)C$sup 11$ REACTION

Journal Article · Mon Feb 10 04:00:00 EST 1964 · Physical Review (U.S.) Superseded in part by Phys.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.133.B639· OSTI ID:4115779

Reeder, P L; Markowitz, S S

The excitation function for the reaction C/sup 12/( pi /sup -/, pi /sup - /n)C/sup was measured from 53 to 1,610 Mev by bombarding targets of plastic scintillator with pions. The intensity of the pion beam was monitored with a two- counter telescope and 40Mc scaling system. The scintillator target was mounted on a phototube and became the detector for the C/sup 11/ positron activity. Corrections were made for muon contamination in the beam, coincidence losses in the monitor system C/sup 11/ activity produced by stray background at the accelerator, C/sup 11/ activity produced by secondaries in the target, and the efficiency of the C/sup 11/ detection system. The C/sup 12/( pi /sup -/, pi /sup /n)C/sup 11/ cross sections rise from a threshold at about 50 Mev to a peak of about 70 mb at 190 Mev after which they decrease to 30 mb at 373 Mev and are relatively constant at higher energies. The ( pi /sup -/, pi /sup -/n) peak occurs at the same energy as the resonance in free-particle pi /sup -/n scattering at 190 Mev. Calculations based on a knock-on collision mechanism and sharp-cutoff nuclear density reproduce the shape of the experimental excitation function, but the magnitudes of the calculated cross sections are low by a factor of about 5 or 6. This simple naodel indicates that the C/sup 12/( pi /sup -/ pi / sup -/n)C/sup 11/ reaction occurs in the nuclear surface region at all bombarding energies. (auth)

• Research Organization: Univ. of California, Berkeley
• NSA Number: NSA-18-009394
• OSTI ID: 4115779
• Report Number(s): UCRL-10924; 0031-899X
• Journal Information: Physical Review (U.S.) Superseded in part by Phys.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 D, Journal Name: Physical Review (U.S.) Superseded in part by Phys.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: 133; ISSN PHRVA
• Country of Publication: United States
• Language: English

Related Subjects

ACCELERATORS
BACKGROUND
BEAMS
CARBON 11
CARBON 12
COINCIDENCE METHODS
CROSS SECTIONS
EFFICIENCY
ENERGY RANGE
EXCITATION
IMPURITIES
MEASURED VALUES
MEV RANGE
MONITORING
MUONS
NEUTRONS
NUMERICALS
PHOSPHORS
PHYSICS
PIONS
POSITRONS
RADIOACTIVITY
REACTION KINETICS
RESONANCE
SCATTERING
TARGETS