T.J. Mulligan

A study of the neutron-rich isotopes near A = 100 by means of the (t, p) reaction

Abstract The (t, p) reaction has been used to study the nuclides 102 Mo, 106 Ru and 112 Pd, all of which are two neutrons beyond the stable isotopes. A (t, p) spectrum of the 102 Ru(t, p) 104 Ru process was also obtained. The incident triton energy was 15 MeV in all cases and a magnetic spectrograph was used for momentum analysis of the reaction protons with an energy resolution of ≈ 20 keV FWHM resulting. Differential cross sections were measured for many transitions and spin and parity assignments have been made for a number of states. Examination of the results indicates that only 102 Mo shows characteristics of being a transitional nucleus between regions of different nuclear shape whereas the other nuclei studied appear to be in regions where the coupling scheme changes more slowly. The first 2 + state of 102 Mo is markedly lower in excitation energy than in the lighter isotopes and a low-lying 0 + state is excited with large intensity relative to the ground state. The present results agree with previous results from the Berkeley group on the decay of fission fragments and in a qualitative way support several recent theoretical predictions.

Proton-hole states in 209Bi From the 210Po (t, α) reaction

Abstract The 210 Po(t, α) 209 Bi reaction has been studied at 20 MeV triton energy with an overall resolution of 20 keV FWHM. Absolute cross sections were established by a comparison of the (t, α) intensities to elastic triton scattering. The three lowest single-proton states in 209 Bi were observed and spectroscopic factors were extracted from the measured cross sections by DWBA analysis. Starting at 2.43 MeV, six levels were strongly excited. These states have large 2p-1h proton components. The spectroscopic factors were extracted by a comparison of 210 Po(t, α) cross sections to 208 Pb(t, α) 207 T1 single-proton-hole cross sections measured previously at the same bombarding energy. The observed states and their properties were analyzed within the framework of the particle- (or hole) vibration coupling model. Surface vibrational states in 208 Pb coupled to single protons as well as the proton pair addition modes (states in 210 Po) coupled to a proton-hole were included in the analysis.

The (τ, p) reactions on Cr (II). 54Cr(τ, p)56Mn

Abstract The 54Cr(τ, p)56Mn reaction has been studied at 15 MeV incident energy using a multi-angle spectrograph. Ninety-seven transitions were identified up to 5.62 MeV excitation and many of the corresponding proton angular distributions were measured. The systematics of L = 0 angular distributions shapes is discussed in detail and criteria for distinguishing L = 0 and L = 0 + 2 transitions are derived. The implication of the present data for the nuclear structure of 56Mn is commented upon and the distribution of 1+ (τ, p) strength in 56Mn is discussed.

One- and three-quasiparticle states in 121Sn

Abstract The reactions 119 Sn(t, p) 121 Sn and 120 Sn(t, d) 121 Sn have been studied at 13 MeV bombarding energy with energy resolutions of 15 keV and 11 keV, respectively. Angular distributions were measured from 12° to 66° in 6° steps and values of the transferred orbital angular momentum were derived. In the (t, d) case, spectroscopic factors are presented. Considerable f-strength from the (t, d) reaction is found near 2.5 MeV, which is about 2 MeV lower than expected from the single-particle model. One- and three-quasiparticle components of the 121 Sn states are examined in some detail. It is concluded that in spite of considerable mixing, the low-lying levels seem amenable to a core-particle description.

Structure of 205Hg from T = 452 states in 205Tl

Abstract The elastic and inelastic proton scattering excitation functions were measured from a 204 Hg target at bombarding energies from 14.0 MeV to 16.4 MeV, and at scattering angles of 30.5°, 125°, 149.5° and 165°. The elastic scattering data show T = 45 2 , l = 4 resonances in 205 Tl at 14.72 and 15.43 MeV, an l = 2 resonance at 15.81 MeV, and another possible l = 2 resonance apparently at 16.5 MeV, which is near the upper limit of the experiment. The inelastic scattering to the first excited 2 + state does not exhibit sharp distinct resonances at the first three of these energies, whereas evidence for a strong resonance structure is found corresponding to the 16.5 MeV elastic resonance. The elastic data are analysed to yield resonance parameters: E res , Γ total and Γ p for each resonance. The observed splitting of the g 9 2 and d 5 2 strength interpreted in terms of the structure of 205 Hg based on the particle-core coupling model.

(h, p) Reactions on Cr: (I). 50Cr(h, p)52Mn

Abstract The reaction 50 Cr(h, p) 52 Mn has been studied at 16.5 MeV incident energy and with a resolution of ≈ 15 keV FWHM. Forty-nine transitions were observed up to 5.87 MeV of excitation and proton angular distributions were extracted. The distribution shapes in conjunction with DW calculations are used for assignments of spin and parity of many final states. The data are compared to previous information on 52 Mn and two states at 2.929 MeV and 5.491 MeV are assigned as isobaric analogues of the two lowest 0 + states in 52 Cr. The strength of the 0 + → 1 + excitations is commented upon.

(h,p) REACTIONS ON Cr. I.

Abstract The reaction 50 Cr(h, p) 52 Mn has been studied at 16.5 MeV incident energy and with a resolution of ≈ 15 keV FWHM. Forty-nine transitions were observed up to 5.87 MeV of excitation and proton angular distributions were extracted. The distribution shapes in conjunction with DW calculations are used for assignments of spin and parity of many final states. The data are compared to previous information on 52 Mn and two states at 2.929 MeV and 5.491 MeV are assigned as isobaric analogues of the two lowest 0 + states in 52 Cr. The strength of the 0 + → 1 + excitations is commented upon.

sup 50

Abstract The reaction 50 Cr(h, p) 52 Mn has been studied at 16.5 MeV incident energy and with a resolution of ≈ 15 keV FWHM. Forty-nine transitions were observed up to 5.87 MeV of excitation and proton angular distributions were extracted. The distribution shapes in conjunction with DW calculations are used for assignments of spin and parity of many final states. The data are compared to previous information on 52 Mn and two states at 2.929 MeV and 5.491 MeV are assigned as isobaric analogues of the two lowest 0 + states in 52 Cr. The strength of the 0 + → 1 + excitations is commented upon.