C.J. Orth

Decay of 245Am

Abstract The γ-ray and conversion electron spectra of 245 Am (2.08 h) have been studied with Ge(Li) and Si(Au) detectors. Three γ-transitions were observed, with energies (in keV) and relative intensities (in percent per disintegration) as follows: 240 (1.2), 252.3 (20) and 296 (0.55). Conversion coefficient measurements indicate that the 252.3 keV transition is predominantly M1. It is concluded that the previously reported 0.905 MeV β-transition proceeds to the ground state of 245 Cm, and that its total intensity is 78%, corresponding to a log ft value of 6.3. Two other levels, of energy 252.3 and 296 keV, are populated by direct β-transitions, the respective β-intensities (and log ft values) being ≈ 17% (6.4) and ≈ 5% (6.9). The characteristics of the observed levels are readily interpretable in terms of the Nilsson model.

Decay of 245Pu

Abstract The radiations associated with the β-decay of 10.5 h 245 Pu have been studied with Ge(Li) and Si(Li) detectors, a xenon-filled proportional counter and conventional NaI(Tl) scintillators used in singles and coincidence configurations. The β-ray spectrum is complex with a 1210±40 keV end-point energy. The most intense group has a 930±30 keV end-point energy. Conversion electron lines of the more intense γ-transitions have been measured and tentative multipolarities have been assigned. A total of 70 γ-rays was observed in Ge(Li) singles spectra, and most of these transitions have been included in the 245 Am level scheme, which includes excited states at 19, 28, 47, 70, 87, 124, 134, 327, 396, 475, 757, 796, 887, 920, 958, 988, 1066, 1112 and 1185 keV. The present data are consistent with spin and parity assignments of 9 2 − for 245 Pu and 5 2 + for 245 Am. The total β-disintegration energy of 245 Pu is 1.26±0.03 MeV.

(. pi. ,. pi. N) reactions in /sup 48/Ca

Excitation functions for the formation of /sup 47/Ca and /sup 47/K from /sup 48/Ca with 100-, 180-, and 300-MeV ..pi../sup + -/ have been determined by activation methods. The contributions of both quasifree and nonquasifree processes are observed in the excitation functions. Unlike (..pi..,..pi..N) reactions on /sup 12/C, final-state nucleon charge exchange is found to play only a minor role in /sup 48/Ca. This decreasing importance of nucleon charge exchange with increasing nuclear mass is explained by a newly-developed (..pi..,..pi..N) theory. In order to establish the magnitude of nucleon charge exchange in medium-mass nuclei, we have measured the cross section for the reaction /sup 45/Sc(..pi../sup -/,..pi..N)/sup 44/K at 180 MeV. An upper limit of 0.25 mb has been determined.

( pi, pi N) reactions in 48Ca.

Excitation functions for the formation of /sup 47/Ca and /sup 47/K from /sup 48/Ca with 100-, 180-, and 300-MeV ..pi../sup + -/ have been determined by activation methods. The contributions of both quasifree and nonquasifree processes are observed in the excitation functions. Unlike (..pi..,..pi..N) reactions on /sup 12/C, final-state nucleon charge exchange is found to play only a minor role in /sup 48/Ca. This decreasing importance of nucleon charge exchange with increasing nuclear mass is explained by a newly-developed (..pi..,..pi..N) theory. In order to establish the magnitude of nucleon charge exchange in medium-mass nuclei, we have measured the cross section for the reaction /sup 45/Sc(..pi../sup -/,..pi..N)/sup 44/K at 180 MeV. An upper limit of 0.25 mb has been determined.

(PI, PI N) REACTIONS IN CA-48

Excitation functions for the formation of /sup 47/Ca and /sup 47/K from /sup 48/Ca with 100-, 180-, and 300-MeV ..pi../sup + -/ have been determined by activation methods. The contributions of both quasifree and nonquasifree processes are observed in the excitation functions. Unlike (..pi..,..pi..N) reactions on /sup 12/C, final-state nucleon charge exchange is found to play only a minor role in /sup 48/Ca. This decreasing importance of nucleon charge exchange with increasing nuclear mass is explained by a newly-developed (..pi..,..pi..N) theory. In order to establish the magnitude of nucleon charge exchange in medium-mass nuclei, we have measured the cross section for the reaction /sup 45/Sc(..pi../sup -/,..pi..N)/sup 44/K at 180 MeV. An upper limit of 0.25 mb has been determined.

Excitation functions of theI127(π, πxn)reactions in the region of the (3,3) resonance

Excitation functions have been determined for the formation of ten iodine nuclides (/sup 117/I-- /sup 126/I) in the interaction of 60--350 MeV ..pi../sup +/ and ..pi../sup -/ with /sup 127/I. The contribution of various reaction mechanisms has been estimated from the systematic features of the excitation functions and isotopic yield distributions with the aid of cross sections obtained for the production of various isobaric xenon nuclides, cross-section results for 500 MeV proton bombardment of /sup 127/I, and comparison with Monte Carlo cascade-evaporation calculations. It is found that, with varying importance, mechanisms involving direct neutron knockout, pion inelastic scattering plus evaporation, pion absorption, and pion charge exchange contribute to the observed yields.

Excitation functions of the /sup 127/I(. pi. ,. pi. xn) reactions in the region of the (3,3) resonance

Excitation functions have been determined for the formation of ten iodine nuclides (/sup 117/I-- /sup 126/I) in the interaction of 60--350 MeV ..pi../sup +/ and ..pi../sup -/ with /sup 127/I. The contribution of various reaction mechanisms has been estimated from the systematic features of the excitation functions and isotopic yield distributions with the aid of cross sections obtained for the production of various isobaric xenon nuclides, cross-section results for 500 MeV proton bombardment of /sup 127/I, and comparison with Monte Carlo cascade-evaporation calculations. It is found that, with varying importance, mechanisms involving direct neutron knockout, pion inelastic scattering plus evaporation, pion absorption, and pion charge exchange contribute to the observed yields.

EXCITATION FUNCTION OF THE I-127 (PI, PI X N) REACTIONS IN THE REGION OF THE (3,3) RESONANCE

Excitation functions have been determined for the formation of ten iodine nuclides (/sup 117/I-- /sup 126/I) in the interaction of 60--350 MeV ..pi../sup +/ and ..pi../sup -/ with /sup 127/I. The contribution of various reaction mechanisms has been estimated from the systematic features of the excitation functions and isotopic yield distributions with the aid of cross sections obtained for the production of various isobaric xenon nuclides, cross-section results for 500 MeV proton bombardment of /sup 127/I, and comparison with Monte Carlo cascade-evaporation calculations. It is found that, with varying importance, mechanisms involving direct neutron knockout, pion inelastic scattering plus evaporation, pion absorption, and pion charge exchange contribute to the observed yields.