Excited states in the T-z = -1 nucleus V-44 have been observed for the first time. The states have been identified through recoil-gamma-gamma coincidences and comparison with analogue states in the mirror nucleus Sc-44. Mirror energy differences have been extracted and compared to state-of-the-art fp shell-model calculations which include charge symmetry breaking forces.

E. K. Johansson,1 D. Rudolph,1 I. Ragnarsson,2 L.-L. Andersson,1 D. A. Torres,3,* C. Andreoiu,4,† C. Baktash,5 M. P. Carpenter,6 R. J. Charity,7 C. J. Chiara,7,‡ J. Ekman,1,§ C. Fahlander,1 O. L. Pechenaya,7,‖ W. Reviol,7 R. du Rietz,1,¶ D. G. Sarantites,7 D. Seweryniak,6 L. G. Sobotka,7 C. H. Yu,5 and S. Zhu6 1Department of Physics, Lund University, S-22100 Lund, Sweden 2Division of Mathematical Physics, LTH, Lund University, S-22100 Lund, Sweden 3Departamento de Fı́sica, Universidad Nacional de Colombia, Bogotá, Colombia 4Department of Physics, University of Guelph, Guelph, Ontario, Canada N1G 2W1, Canada 5Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA 6Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA 7Chemistry Department, Washington University, St. Louis, Missouri 63130, USA (Received 29 January 2009; published 30 July 2009)

The combined data from three fusion-evaporation reaction experiments have been utilized to investigate the semi-magic nucleus Ni-58(28)30. To detect gamma rays in coincidence with evaporated particles, the Ge-detector array Gammasphere was used in conjunction with the charged-particle detectors Microball and LuWuSiA (the Lund Washington University Silicon Array), and a neutron detector array. The results yield a significantly extended level scheme of Ni-58 comprising some 340 gamma-ray transitions and include a total of at least 14 discrete particle decays into excited states of the daughter nuclei Fe-54 and Co-57. The level scheme is compared with large-scale shell-model calculations and cranked Nilsson-Strutinsky calculations.

A largely extended experimental knowledge of the Cu-61(29)32 nucleus has been obtained from three experiments. Excited states in Cu-61 were produced via the fusion-evaporation reaction Si-28(Ar-36, 3p)Cu-61. In addition to the Ge array GAMMASPHERE, neutron and charged-particle detectors placed around the target position were used for high-performance particle spectroscopy. The constructed level scheme includes more than 160 energy levels and 320 gamma-ray transitions belonging to both normally deformed as well as superdeformed rotational structures. The multipolarities have been determined for the gamma-ray transitions and as a result spin-parity assignments are given for nearly all energy levels. Experimental results in the normally deformed region are compared with predictions from large-scale shell model calculations. The collective structures are compared with results from cranked Nilsson-Strutinsky calculations. The results reveal the need to modify the standard Nilsson parameters in the mass A similar to 60 region. (Less)

The ${21}^{+}$ isomer in $^{94}\mathrm{Ag}$ has recently been reported to have a two-proton decay branch to $^{92}\mathrm{Rh}$. We have populated $^{92}\mathrm{Rh}$ through the $^{40}\mathrm{Ca}$($^{58}\mathrm{Ni}$,$\ensuremath{\alpha}\mathit{pn}$) reaction at 240 MeV, and have performed detailed spectroscopic measurements of the levels, finding new states and measuring angular distributions of \ensuremath{\gamma} rays. We find no evidence for the states reported to be populated by the two-proton decay of $^{94}\mathrm{Ag}$${}^{m}$. The calculated $Q$-value for the two-proton decay implies that this process directly feeds low-lying yrast, or near-yrast, states in $^{92}\mathrm{Rh}$, which is very difficult to reconcile with our observations. Several scenarios for the population of $^{92}\mathrm{Rh}$ are discussed, none of which appears to be satisfactory.

In the fusion-evaporation reaction Ca-40+Mg-24 at 104 MeV beam energy, excited states have been observed for the first time in the isotope Ga-31(61)30. The experimental setup comprised the Ge array CLARION, a recoil mass spectrometer and, in its focal plane, an ionization chamber. Five transitions in Ga-61 are identified, out of which a cascade of three transitions has been established by means of recoil-gammagamma coincidences. The strong transitions at 271 keV in Ga-61 and 124 keV in Zn-61 are viewed as the "mirror" 5/2(-)-->3/2(-) ground-state transitions. The rather large energy difference of 150 keV is suggested to arise from Coulomb monopole contributions. Shell-model calculations support this interpretation.

In the fusion-evaporation reaction $^{40}\mathrm{Ca}+^{24}\mathrm{Mg}$ at $104\phantom{\rule{0.3em}{0ex}}\text{MeV}$ beam energy, excited states have been observed for the first time in the isotope ${^{31}_{61}\mathrm{Ga}}_{30}$. The experimental setup comprised the Ge array CLARION, a recoil mass spectrometer and, in its focal plane, an ionization chamber. Five transitions in $^{61}\mathrm{Ga}$ are identified, out of which a cascade of three transitions has been established by means of recoil-$\ensuremath{\gamma}\ensuremath{\gamma}$ coincidences. The strong transitions at $271\phantom{\rule{0.3em}{0ex}}\text{keV}$ in $^{61}\mathrm{Ga}$ and $124\phantom{\rule{0.3em}{0ex}}\text{keV}$ in $^{61}\mathrm{Zn}$ are viewed as the ``mirror'' $5/{2}^{\ensuremath{-}}\ensuremath{\rightarrow}3/{2}^{\ensuremath{-}}$ ground-state transitions. The rather large energy difference of $150\phantom{\rule{0.3em}{0ex}}\text{keV}$ is suggested to arise from Coulomb monopole contributions. Shell-model calculations support this interpretation.

With this letter we express our intention to submit a proposal for studies of the physics of light proton rich systems close to the N=Z line in the vicinity of Mg. In particular we aim at improving the knowledge of the ground state wave function of Al. This nucleus is of interest in nuclear astrophysics as well as in pure nuclear structure. Its properties may e.g. influence the production of Na in nova explosions which in turn can be observed by space born gamma-ray telescopes.