P.V. Drumm

Masses and level schemes of 33Si and 34Si

Abstract The mass excesses of 33Si and 34Si have been measured using the 36S(11B, 14, 13N)33, 34Si; reactions. Values of −20.550 ± 0.030 MeV ( 33 Si) and −20.017 ± 0.025 MeV ( 34 Si) were obtained. In addition, an excited state of 34Si was observed at 5.33 ± 0.05 MeV, and excited levels of 33Si were observed at 1.06 ± 0.02 and 4.32 ± 0.03 MeV. These results are compared with recent shell-model calculations.

The 26Mg(18O, 17F)27Na and 26Mg(18O, 15O)29Mg reactions and the level schemes of 27Na and 29Mg

Abstract The 26 Mg( 18 O, 17 F) 27 Na and 26 Mg( 18 O, 15 O) 29 Mg reactions have been used to determine the ground-state masses and partial level schemes of 27 Na and 29 Mg. Values of −5514 ± 60 keV and −10600 ± 45 keV were determined for the mass excesses of 27 Na and 29 Mg, respectively. The probable structure of some of the levels observed was deduced from a comparison with shell-model calculations and with previous experimental information. A number of other 18 O- and 16 O-induced reactions on magnesium targets were also studied in order to obtain information on the reaction mechanisms of the ( 18 O, 17 F) and ( 18 O, 15 O) reactions.

Ground-state mass excesses and low-lying levels of the neutron-rich nuclei 36P, 35P and 34P

Abstract The ground-state masses and the excitation energies of low-lying levels of the nuclei 36P, 35P and 34P have been measured using the 36,34S(7Li,7Be)36,34P charge-exchange reactions, and the one-nucleon-transfer reaction 36S(6Li, 7Be)35P. Mass-excess values of −20.251 ± 0.027 MeV ( 36 P ), −24.828 ± 0.017 MeV ( 35 P ) , and −24.569 ± 0.040 MeV ( 34 P ) were obtained. A single excited state is observed at 252 ± 10 keV in 36 P , and a number of new levels are observed in the nuclei 35P and 34P. The 36,34S(11B, 11C)36,34P reactions were also studied in order to remove ambiguities associated with the 429 keV level in 7Be.

The mass of 35Si

Abstract The mass excess of 35 Si has been determined as −14.427 ± 0.060 MeV from a measurement employing the 36 S( 13 C, 14 O) 35 Si reaction. No excited states of 35 Si were observed. The 34 S( 13 C, 14 O) 33 Si reaction was studied simultaneously, and previously unreported excited states in 33 Si were observed at 1.47, 2.00, 3.19, 4.13 and 5.48 MeV.

The 20Ne(16O,16O)20Ne excitation function at θc.m. = 90° and parity-dependent interactions

Abstract The excitation function for 16 O + 20 Ne elastic scattering at θ c.m. = 90° has been measured over the energy range 21.5 MeV E c.m. 16 O− 20 Ne potential. A satisfactory description is obtained of elastic scattering excitation functions at θ c.m. = 90° and θ c.m. = 154° ± 2° with a potential which is deeper for even than for odd partial waves. Such a parity dependence is consistent with the assumption that this term arises from a requirement to simulate the effects of α-transfer amplitudes, and with the expectations of models which argue that parity dependence is to be expected as a consequence of the Pauli principle.

The mass and low-lying levels of 40Cl

Abstract The mass excess of the T z = 3 nucleus 40 Cl has been determined using the 40 Ar( 7 Li, 7 Be) 40 Cl reaction. A value −27.527 ± 0.035 MeV was obtained. A number of excited states of 40 Cl were a1so observed. In addition, the 40 Ar( 11 B, 11 C) 40 Cl and 40 Ar( 11 B, 13 N) 38 S reactions were investigated. Excited states of 38 S were observed at 1.28 ± 0.04 and 3.38 ± 0.10 MeV.

A study of 25Ne via the 26Mg(13C, 14O)25Ne reaction

Abstract The mass of 25 Ne has been determined from the Q -value of the reaction 26 Mg( 13 C, 14 O) 25 Ne at a 13 C energy of 96 MeV. The 14 O ions were momentum-analysed using an Enge split-pole spectrometer and detected at the focal plane in a multi-element, gas-filled detector. The resulting mass excess for 25 Ne is −2.03±0.05 MeV. Excited states of 25 Ne were observed at energies of 1.74±0.03, 3.33±0.03, 4.07±0.03 and 6.28±0.05 MeV. The widths of the states at 1.74 and 3.33 MeV suggest that they may be unresolved doublets, the levels being separated by approximately 110 and 200 keV, respectively. A qualitative discussion of the possible reaction mechanisms and of the nuclear structure of the observed states is presented and a comparison made with recent shell-model calculations.