Experimental study of radiative pion capture on /sup 13/C, /sup 20/Ne, /sup 90/Zr, /sup 19/F, and /sup 12/C

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1980

OSTI ID:6143505

Martoff, C J

Photon spectra for 50 < E/sub ..gamma../ < 135 MeV have been measured from the radiative capture of stopped negative pions by the nuclides /sup 13/C, /sup 19/F, /sup 20/Ne, and /sup 90/Zr. The e/sup +/e/sup -/ pair spectrometer system used has resolution 850 keV FWHM and photon detection efficiency 5 10/sup -6/. The total radiative capture branching ratios measured are: /sup 13/C (1.66 +- 0.25)%, /sup 19/F (2.40 +- 0.48)%, /sup 20/Ne (1.60 +- 0.24)%, and /sup 90/Zr(2.1 +- 0.5)%. The partial radiative capture branching ratios to four bound states and two resonances in /sup 20/F, and two bound states and three resonances in /sup 13/B have also been measured. The branching ratio /sup 13/C(..pi../sup -/,..gamma..)/sup 13/B g.s. is (6.1 +- 1.2) 10/sup -4/. Comparison of this result with the beta decay rate of /sup 13/B shows that (84 +- 16)% of the pion capture amplitude is accounted for by the Gamow-Teller matrix element. Further analysis suggests that much of the remaining strength is E2. The measured branching ratios to resonant states in /sup 13/C(..pi../sup -/,..gamma..)/sup 13/B are shown to be in agreement with detailed shell model calculations of this process. The total single-particle strength in these transitions is shown to be approximately half as large as that of the T = 3/2 part of E1 photoresonance (the Giant Dipole Resonance) in /sup 13/C. The branching ratio for /sup 20/Ne(..pi../sup -/,..gamma..)/sup 20/F (T = 1, J/sup ..pi../ = 1/sup +/, E/sub x/ = 1.06 MeV) is (0.91 +- 0.52) 10/sup -4/. Comparison with the electroexcitation of the analog giant M1 state in /sup 20/Ne (11.24 MeV) shows that the M1 transition amplitude is less than 46 +- 14)% Gamow-Teller. This result is in agreement with detailed shell model calculations of the M1 transition. The photon spectrum for radiative pion capture from flight (reaction /sup 12/C(..pi../sup +/ T = 44 MeV, ..gamma.. at 90/sup 0/)) has been measured.

• Research Organization: California Univ., Berkeley (USA)
• OSTI ID: 6143505
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BORON 13
BORON ISOTOPES
BRANCHING RATIO
CAPTURE
CARBON 12 TARGET
CARBON 13 TARGET
CHARGED-PARTICLE REACTIONS
DATA
ENERGY-LEVEL TRANSITIONS
EXPERIMENTAL DATA
FLUORINE 19 TARGET
FLUORINE 20
FLUORINE ISOTOPES
GAMMA SPECTRA
GIANT RESONANCE
HADRON REACTIONS
INFORMATION
ISOTOPES
LIGHT NUCLEI
MATHEMATICAL MODELS
MESON REACTIONS
NEON 20 TARGET
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
PION MINUS REACTIONS
PION PLUS REACTIONS
PION REACTIONS
RADIOISOTOPES
RESONANCE
SECONDS LIVING RADIOISOTOPES
SHELL MODELS
SPECTRA
TARGETS
ZIRCONIUM 90 TARGET