K. Grabisch

States in 12C and 16O investigated by the 11B(d, n) and 15N(d, n) reactions

Abstract Neutrons from the 6 MeV deuteron bombardment of 11 B and 15 N have been investigated by the time-of-flight method. Angular distributions of (d, n) transitions to nine states in 12 C up to 16.11 MeV and to five states in 16 O up to 8.88 MeV excitation energy are obtained and analysed with DWBA theory to yield l -values and spectroscopic factors. The results are reasonably well interpreted in the framework of the shell model by ascribing a predominant one-particle-one-hole component to most of the observed excited states. Prominent exceptions are the 0 + (7.66 MeV) state in 12 C and the 2 + (6.92 MeV) state in 16 O for which a more complicated structure is required.

Investigation of states in 40Ca by the 39K(d, n) reaction

Abstract Neutrons from the 6 MeV deuteron bombardment of 39 K have been investigated by the time-of-flight method; 30 angular distributions of (d, n) transitions to states in 40 Ca up to an excitation energy of 10 MeV are obtained. They have been analysed with DWBA to yield l -values and spectroscopic factors. The l = 1 character of 14 transitions to states above 7.9 MeV determines their parity to be negative. From comparison with 39 K(d, p) data, four levels above 9.4 MeV are proposed as possible analogues of 40 K states with dominant d 3 2 −1 p 3 2 configuration. The experimental transition strengths are compared to previous (τ, d) results and to predictions of the simple shell model. The main component of two shell-model particle-hole states is found in two other 40 Ca states than in previous investigations. At least 45% of the d 3 2 −1 p strength is moved away from the zero-order particle-hole states of the shell model. Theoretical spectroscopic factors were derived from the wave functions of Gerace and Green obtained by mixing spherical 1p-1h states with deformed 3p-3h states. Near to quantitative agreement with experiment is observed.

The 60Ni(d,n) reaction above and below the Coulomb barrier and the deuteron optical-model potential

Abstract Neutrons from the deuteron bombardment of 60 Ni have been investigated with the time-of-flight method. Angular distributions have been obtained at 6 and 3.8 MeV bombarding energies. The differential cross sections at E d = 6 MeV are analysed with DWBA to yield l -values and spectroscopic factors. These are compared to previous measurements and to weak-coupling predictions. From the differential cross sections of the ground state transition, deuteron optical-model potentials have been evaluated for 6 and 3.8 MeV bombarding energies by means of a DWBA search procedure. It is shown that the (d,n) reaction allows a determination of the deuteron potential at subcoulombic energies, where the elastic scattering may not be used for this purpose.

Study of states in 25Al and 26Al by the 24Mg(d, n) and 25Mg(d, n) reactions

Abstract Neutrons from the 5.5 or 6 MeV deuteron bombardment of 24 Mg and 25 Mg, respectively, have been investigated by the time-of-flight method. Angular distributions of (d, n) transitions to eight states in 25 Al up to 3.08 MeV and to 38 states in 26 Al up to 6.1 MeV excitation energy are obtained. The stronger transitions, altogether 33, have been analysed with DWBA theory to yield l -values and spectroscopic factors. The observed l -values of the 25 Mg(d, n) transitions determine the spin of the 26 Al states at 2.66, 5.13 and 5.49 MeV to 2 or 3, their parity as positive and the parity of the levels at 4.699, 4.766 and 5.24 MeV also as positive. Negative-parity states appear at 5.39, 5.45 MeV, around 5.7 MeV and at 5.91 MeV. From comparison with 25 Mg(d, p) 26 Mg, isospin T = 1 is proposed for the levels at 5.13 and 5.24 MeV, and spins I = 2 and I = (2, 3), respectively. The experimental spectroscopic factors are compared to predictions of the Nilsson model for 25 Al and 26 Al. No substantial agreement is obtained for 26 Al, whereas the 25 Al results are compatible with the theory. A comparison of spectroscopic factors from the 25 Mg(d, n) 26 Al and the 25 Mg( 3 He, d) 26 Al reactions is included and discussed.

Study of 15O states by the 14N(d, n) reaction

Abstract The reaction 14N(d, n)15O has been investigated at 5.6 and 6.0 MeV bombarding energy by means of the neutron time-of-flight method. Angular distributions for nine final states have been extracted and analysed with DWBA and Hauser-Feshbach calculations to yield spectroscopic factors. These are compared to results of previous experiments and of shell-model calculations. The p−2d 3 2 . configuration is strongly mixed with the states of the p−2(d 5 2 , s 1 2 ) conf its inclusion therefore is necessary for a correct description of low-lying even-parity states of 150.

The reactions 36, 38, 40Ar(3He, n)38, 40, 42Ca and 40, 42Ca(3He, n)42, 44Ti

Abstract Energy spectra and angular distributions of neutrons from the ( 3 He, n) reaction on 36, 38, 40 Ar at 11.5 MeV and 40, 42 Ca at 13 MeV bombarding energy have been measured with the time-of-flight technique. Comparisons between measured angular distributions and distorted-wave Born approximation (DWBA) calculations provide a number of new spin-parity assignments. The transitions to 0 + states are compared with predictions of the shell model and the pairing vibrational model.

Study of 59Cu by means of 58Ni(d, n)

Abstract The reaction 58 Ni(d, n) 59 Cu has been studied at 7.0 MeV bombarding energy. Angular distributions of transitions to 16 states in 59 Cu have been extracted and analysed with DWBA to yield absolute spectroscopic strengths. The results are compared to those of other measurements.

Observation of weakly coupled 2p-1h states in 41Ca from proton transfer on 40K

Abstract The proton transfer on 40K has been studied with the 40K(3He, d)41Ca reaction at 13 and 21 MeV bombarding energy and with the 40K(d, n)41Ca reaction at 6.5 MeV bombarding energy. The energy and angular distribution of outgoing particles have been measured. For transitions to 62 levels in 41Ca the l-values and spectroscopic factors have been derived with DWBA. The excitation energies of levels populated with l = 3 and the qualitative distribution of transfer strength strongly suggest their interpretation as 2p-1h states of the f 7 2 2d 3 2 −1 configuration with weak coupling between the particle pair and the hole. The high-spin states of this configuration (with Jπ up to 15 2 + ) are preferentially excited.

Spectroscopic study of 15N states with the reaction 14C(d, n)

Abstract Energy and angular distributions of neutrons from the reaction 14C(d, n)15N have been measured at 6.5 MeV deuteron energy. The DWBA analysis yielded l-values and absolute spectroscopic factors for fifteen states in 15N below 10 MeV excitation energy. For the 9.23 MeV level Jπ is determined to be 3 2 + or 5 2 +, for the 9.93 MeV level the data suggest J π = 1 2 + . The spectroscopic factors are in qualitative agreement with pure jj coupling and in semi-quantitative agreement with shell-model calculations.

Spectroscopy of 93, 95Tc by means of 92, 94Mo(d, n)

Abstract The reactions 92, 94Mo(d, n) have been investigated with the time-of-flight method at 6.25 and 7.0 MeV bombarding energy. Ten levels in 93Tc and 16 levels in 95Tc have been observed. Excitation energies and angular distributions have been obtained. Analysis with DWBA yielded l-values and transition strengths. Spin and parity of three levels in 93Tc and ten levels in 95Tc are found to be 1 2 + because they are populated by l = 0 transfer. Shell-model orbit occupation probabilities of the target ground states are derived by means of sum rules.