S. Hinds

The (t, p) reaction with the even isotopes of Ca

Abstract The reactions 40, 42, 44, 46, 48 Ca(t, p) were investigated at 10 to 12 MeV bombarding energy with an overall energy resolution of 15–25 keV. The relative differential (t, p) cross sections for the strongest L = 0 transitions in the various isotopes were measured by means of a target composed of approximately equal amounts of the various even Ca isotopes. The systematic trends of the (t, p) angular distribution shapes were established for angular momentum transfers of 0, 2, 3 and 4 units of ħ. A number of 0 + , 2 + and 4 + assignments was made. A detailed comparison of the data from the one- and two-neutron capture reactions leading to 44 Ca is presented, and the systematics of the 0 + states in the Ca isotopes is discussed. Two distinct groups of 0 + states, both characterized by large (t, p) cross sections, were observed; one group comprises the 42, 44, 46, 48 Ca ground states and the second group consists of the following states: 5.85 MeV 42 Ca, 5.864 MeV 44 Ca, 5.595 and 5.628 MeV 46 Ca, 5.459 MeV 48 Ca and 50 Ca (ground state).

Proton pick-up from the even lead nuclei

Abstract Angular distributions of the Pb(t, α) reactions leading to states of 207Tl, 205Tl and 203Tl have been measured at an incident triton energy of 13.5 MeV using the Aldermaston tandem accelerator and multi-angle magnetic spectrograph. The states of 207Tl are probably single-proton hole states and were observed at excitations of 0 MeV (3 s 1 2 ) −1 ; 0.35 MeV , (2 d 3 2 ) −1 ; 1.34 MeV , (1 h 11 2 ) −1 ; 1.67 MeV , (2 d 5 2 ) −1 and 3.48 MeV possibly (1 g 7 2 ) −1 . For 205Tl sixteen excited states were observed up to an excitation of 2.74 MeV, and for 203Tl nine excited states were observed up to 1.69 MeV. The number of excited states observed in these two nuclei is in rough agreement with the prediction of the model of a single proton hole coupled to the states of the corresponding Pb cores. Some of the angular distributions for the three Tl isotopes have been analysed using distorted wave methods and spectroscopic factors were extracted. These factors for the four lowest states of 207Tl support the single-hole assignments and for the states of 205Tl and 203Tl are within the sum rule limits. The results are discussed on the basis of the above model.

Proton pick-up from the even calcium isotopes

Abstract The 42, 44, 46, 48Ca(t, α) proton pick-up reactions have been investigated at about 13 MeV incident energy, transition Q-values and α-particle angular distributions were measured for the stronger transitions. A common intensity scale was established by means of (t, α) reactions from a target consisting of known amounts of each of the even Ca isotopes. Assignments of l-values were made on the basis of the α-particle angular distributions. Relative spectroscopic factors were obtained by means of a DW analysis for the strongest 1 f 7 2 , 1 d 3 2 and 2 s 1 2 transitions. Some 1 f 7 2 transitions were observed for the targets of 40, 42, 44, 46Ca but not for 48Ca.

States of 208Pb from double triton stripping

Abstract The reaction 206 Pb(t, p) 208 Pb was investigated at an incident energy of 12 MeV, the protons being momentum analysed in a multi-angle magnetic spectrograph. A total of 56 excited states of 208 Pb was observed up to an excitation energy of 7.6 MeV. Strong excitations were found for the ground state, the 2.62 MeV 3 − state and the 3.20 MeV 5 − state, but the 3.71 MeV 5 − state was not observed. The different behaviour of these states in (d, p), (t, p) and inelastic scattering experiments is discussed. A state at 4.87 MeV in 208 Pb is assigned 0 + from the shape of the corresponding (t, p) angular distribution which has deep minima at 35° and about 75°. No other excited 0 + states of 208 Pb could be identified from the (t, p) data. It is demonstrated that the existence of two or three sharp minima, the positions of which depend smoothly on the mass number, is a characteristic feature of L = 0 (t, p) angular distributions over a wide range of nuclei. For L = 3 and L = 5 the Pb(t, p) angular distributions at 12 MeV bombarding energy have less characteristic shape than for L = 0.

Nuclear spectroscopy with 204Pb

Abstract The reactions 204 Pb(d, t), 204 Pb(d, p), 204 Pb(d, d′) and 204 Pb(t, p) were investigated at incident energies of 12–13 MeV, the reaction products being momentum analysed in a multi-angle, magnetic spectrograph. Seven excited states were observed in 203 Pb up to 2.8 MeV excitation energy; 27 excited states were observed in 205 Pb up to 4.1 MeV excitation energy; five excited states were identified in 204 Pb up to 2.7 MeV excitation energy, and four excited states were found in 206 Pb up to 3.8 MeV excitation energy. The measured angular distributions from the single transfer reactions (d, p) and (d, t) were compared with DWBA predictions, and spectroscopic factors were deduced for a number of levels. For the states of 203 Pb and 205 Pb near the Fermi surface and for the 204 Pb ground state the results are in general agreement with the pairing model. The data suggest that the four hole-two particle strength of 206 Pb is distributed over many close levels.

The reactions 116, 118Sn(t, p)118, 120Sn

Abstract The 116 Sn(t, p) and 118 Sn(t, p) reactions have been investigated at bombarding energies of 13 and 12 MeV, respectively. The reaction protons were detected at 24 angles between 5° and 175° with an overall energy resolution of 15–20 keV. The proton spectra were dominated by the intense ground-state transitions, but several groups leading to excited states (below E x = 4 MeV) were also identified. The angular distribution systematics is discussed and the (t, p) intensities are compared to qualitative predictions based on the pair-coupling scheme.

The reactions 207,208Pb(t,p)209,210Pb and the two-particle-one-hole states of 209Pb

Abstract The reactions 207,208Pb(t, p)209,210Pb were investigated at 13 MeV bombarding energy. In 210Pb, a total of 35 levels was excited below Ex = 4.7 MeV, and in 209Pb a total of 31 levels was identified below Ex = 4.6 MeV. In the latter nucleus, all of the seven single-neutron states were observed. States at 2.16, 2.74, 2.87 and 2.91 MeV are indentified as two-particle-one-hole states of 209Pb. The transition to the 2.16 MeV level has L = 0, whereas the three latter transitions have L = 2.

Deuteron stripping on even isotopes of Ca (II)

Angular distributions of 40, 42, 44, 46, 48Ca(d, p) reactions were measured at 9.99 MeV bombarding energy, using a multiangle spectograph and a target containing all of the stable even Ca isotopes in a known mixture. Transitions to the odd-A ground states and to the strong 2p72 levels were analysed. Relative cross sections were obtained for these transitions to about 7% accuracy, and absolute cross sections to about 15% accuracy. Q-value differences were measured to about ±2 keV accuracy. A distorted wave analysis is presented and relative spectroscopic strengths and derived to an accuracy of about 10%. The ground state transition strengths deviate from the 8 : 6 : 4 : 2 ratios expected for pure 1f72 configurations. The 47Ca and 49Ca ground state strengths are, within experimental uncertainties, in the pure configuration ratio of 2 : 4.

(t, p) reactions on 112, 124Sn and the pairing model

Abstract The (t, p) reactions on enriched targets of 112, 124Sn were studied at bombarding energies near 13 MeV. Sixteen states in 114Sn and fourteen states in 126Sn were observed. In both cases, the ground-state transitions were the strongest in the spectra. In 114Sn, several transitions at Ex ≲ 3 MeV had intensities between 10 and 20% of the ground state transition, whereas in the 126Sn case no transitions below 5 MeV excitation had intensities above 7% of the ground-state transition. Two 126Sn transitions at 5.31 and 5.76 MeV were of about 10% intensity, whereas in 114Sn no transitions were observed 3.7 MeV with appreciable (> 5%) intensity. The data are discussed in terms of the pairing model.

O+ spectra of 48Ca and 50Ca

Abstract Data from (t,p) reactions on 46,48Ca are reported. New O+ states in 48,50Ca are identified. The character of these states is discussed.