R.A. Ristinen

A study of excited states in 58Cu, 54Co, 50Mn and 46V

Abstract Levels of the doubly odd N = Z nuclei 58 Cu, 54 Co, 50 Mn and 46 V were studied with the (p, nγ) reaction at E p = 7 to 16 MeV. The neutrons were detected in an NE224 scintillator and the γ-rays in coincidence were detected in a Ge(Li) detector. Additional information on the level structure and relative excited state populations was obtained from neutron time-of-flight spectra from the (p, n) reactions and from a triton spectrum from the 46 Ti( 3 He, t) 46 V reaction. Level schemes and restrictions on possible spins based on the γ-ray data are given for each nucleus up to an excitation energy of approximately 2 MeV.

High spin states in 88, 87, 86Zr

Abstract Levels populated by the 84, 86 Sr(α, 2nγ) 84, 88 Zr and 84 Sr(α, nγ) 87 Zr reactions were studied at bombarding energies of 28, 35 and 16.7 MeV, respectively. In addition, levels in 88 Zr populated by the 89 Y(p, 2nγ) 88 Zr reaction were studied at 22.7 MeV incident proton energy. The studies were performed by techniques of in-beam γ-ray spectroscopy. A number of new high spin states in 88 Zr and 87 Zr were observed, and a level scheme for 86 Zr is obtained for the first time. The levels observed are interpreted within a shell-model context.

A study of the 106Pd(p, d)105Pd and 106Pd(3He, d)107Ag reactions

Abstract The 106 Pd(p, d) 105 Pd reaction has been studied at 22.9 MeV with an energy resolution of 13 keV. Angular distributions permitted the assignment of l -values and the extraction of spectroscopic factors for 13 states including several previously unresolved l = 2 transitions. The 106 Pd( 3 He, d) 107 Ag reaction has also been studied at 32.8 MeV with a resolution of 20 keV. Angular distributions were obtained, l -values assigned and spectroscopic factors extracted for 14 levels including many not observed previously in a proton transfer reaction. The level structure of 105 Pd and 107 Ag is discussed particularly in terms of quasirotational bands.

The radioactive decays of 6.7 min 179mW and 38 min 179W

Abstract The decays of 6.7 min 179mW and 38 min 179W have been studied by means of high resolution γ-ray and electron spectroscopy using Ge(Li) and Si(Li) detectors, a broad-range transport solenoid electron spectrometer and γ-γ coincidences with Ge(Li) detectors. The decay of 38 min 179W occurs by a fast beta transition (logft 4.6) and by a first-forbidden beta transition (logft 6.9) followed by a 30.7 keV and by a 133.9 keV γ-transition, respectively. The [521] 1 2 − 6.7 min 179mW decays mainly by an isomeric transition of 221.5 keV (M3) and a competing 101.6 keV (E4)-120.1 (E2) keV cascade to the 179W ground state. A small fraction of the decay of the 6.7 min isomer is observed to proceed by beta transitions to levels in 179Ta. The results are interpreted in terms of the Nilsson model and the following intrinsic proton states are proposed in 179Ta: [404]if 7 2 + giound state; [514]if 9 2 − 30.67 keV; [402]if 5 2 + 238.7 keV; [411]if 1 2 + 520.4 keV; and [541]if 5 2 − , K = 1 2 at 741.5 keV. The [541] if 1 2 − band is observed to have approximately the same large decoupling parameter (a > 4) as has been found in 173,175Lu.

The (3He, d) reaction on 24Mg and 28Si at 38.5 MeV

The (3He, d) reaction at a sufficiently high energy is considered to be a reliable single-proton stripping direct reaction. The data for the low-lying states produced by this reaction on 24Mg and 28Si are compared to the predictions of the strong-coupling rotational model. The agreement with the model predictions for 25Al is quite good, both for the single-proton spectroscopic factors in that nucleus and most particularly for the excitation of 72+ states in 25Al and 29P by two-step processes.

High-spin states above 3.5 MeV in 91Nb

Abstract High-spin states in 91 Nb populated by the 89 Y(α, 2nγ) reaction were studied at 24.0 MeV and 35.7 MeV incident α-particle energy. Gamma-gamma coincidence and γ-ray angular distribution measurements were made. Several high-spin states in 91 Nb were observed at 35.7 MeV bombarding energy which were not observable at 24.0 MeV. The shell model structure of these states is discussed.

The (p, t) reaction on 12C, 54Fe and 208Pb at 80 MeV

Abstract Angular distributions have been measured for the low-lying levels of the residual nuclei for the 12 C, 54 Fe and 208 Pb(p, t) reactions at E p = 80 MeV. The shapes of these angular distributions are generally well reproduced by the zero-range distorted-wave Born approximation (DWBA). Enhancement factors extracted from the data show that the DWBA predicts relative strengths consistent with those observed at lower bombarding energies. However, the overall empirical DWBA normalization at E p = 80 MeV is observed to be 1 12 ( 1 4 ) of that required at 40 MeV for 208 Pb ( 54 Fe).

Level structure of 106Ag

Abstract The level structure of 106 Ag has been investigated through the use of the 103 Rh(α, nγ), 105 Pd( 3 He, d), 107 Ag(p, d) and 104 Pd( 3 He, p) reactions. The charged particle reactions provided the energies of 47 levels ranging up to 1684 keV and l -values were determined from the angular distributions for the neutron and proton transfer reactions to most of the states. Fifty-two γ-rays were assigned as transitions between the levels resulting from the charged particle data. Through the use of a combination of the l -values and γ-ray transitions the members of the 1g 9 2 -2d 5 2 and 2p 1 2 -2d 5 2 configuration multiplets have been deduced. The 6 8.4 d isomeric state has been located at 88 keV. The measurement of Q -values for the charged particle reactions has permitted determination of the mass of 106 Ag with greater precision than previously.

The isomeric decay of 73Se

Abstract The energy of the isomeric transition in 73m Se was measured as25.71 ± 0.04 keV with a double-focussing beta-ray spectrometer. From the L/K conversion electron ratio a unique E3 multipole assignment can be made. From coincidence experiments between L conversion electrons and the low-energy gamma-ray spectrum it is concluded that no gamma-ray transition occurs in cascade with the isomeric decay.

The (3He, t) reaction on 24Mg and 28Si

Abstract The ( 3 He, t) charge exchange reaction on 24 Mg and 28 Si has been studied at 38.5 MeV. The angular distributions provide a number of new spin assignments in 24 Al and 28 P. A two-step excitation through intermediate α-particle channels was used to predict the 24 Al cross sections. The fits are fair in shape, but about a factor of three too large when a perfect overlap of initial and final shapes is assumed. The data to three 1 + states of 28 P are compared to the known electromagnetic reduced transition rate B (M1) to the analog states in 28 Si.