H. Taketani

Level structure of N = 49 nuclei up to an excitation energy of 13 MeV by the (p, d) reaction

Abstract Levels up to an excitation energy of 13 MeV in the N = 49 nuclei, 87 Sr, 89 Zr, 91 Mo, and 88 Y, have been investigated by means of the (p, d) reaction. The incident proton energies were 52 and 55 MeV and the outgoing deuterons were analyzed with a broad-range magnetic spectrometer. The experimental angular distributions were compared with DWBA calculations and the l n values and spectroscopic factors were deduced. A number of new levels including analogue states have been found. The extensive level structure obtained is qualitatively consistent with the concept that most of the levels are due to the fragmentation of the 1 g 9 2 , 2 p 1 2 , 2 p 3 2 and 1 f 5 2 neutron-hole strengths by isospin splitting and core-polarization

Band structures of 76Se and 78Se

Band structures of 76Se and 78Se have been studied with the 74,76Ge(α, 2nγ)76,78Se reactions by using a variety of in-beam γ-techniques : γ-ray singles spectra, γ-ray excitation functions, γ-γ-t coincidences, γ-ray angular distributions and γ-ray linear polarizations. Spins and parities have been assigned uniquely for many new levels in 76Se and 78Se and four bands have been identified in both nuclei: (i) the ground-state band, (ii) a positive-parity ΔJ = 1 band built on the second 2+ state (γ-vibrational band), (iii) a negative-parity Δ J = 2 band built on the 3− state (octupole band) and (iv) a ΔJ = 2 band built on the high-lying J = 4 state. In addition, the second 8 + and 10+ states, which are possibly the lowest members of a band, have been found in both nuclei. Systematics of the band structures obtained are discussed. Level energies of the band members and B(E2) ratios for some of the inter-band transitions between γ- and ground-state bands have been calculated with the proton-neutron interacting boson model IBM-2 and a reasonable agreement with the present data has been obtained.

A three Ge(Li) compton polarimeter for nuclear-reaction gamma-rays

Abstract A convenient arrangement of three Ge(Li) detectors has been employed for the measurement of linear polarization of γ-rays from nuclear reactions. Method and performance involved in this system are described. An example is given describing the determination of the spin, parity and the associated γ-ray multipole mixing ratio for the 1401 keV level of 48 Sc with the 48 Ca(p, nγ) reaction.

Level structure of 89Zr via the reaction 90Zr(p, d)89Zr

Abstract Levels in 89Zr up to about 13 MeV have been excited via the reaction 90Zr(p,d)89Zr. The over-all level structure obtained is qualititively consistent with the concept that most of the levels are due to 9 2 , 2 p 1 2 , 2 p 3 2 , 1 f 5 2 , and possibly 1 7 2 neutron hole states fragmented by isospin splitting and core-polarization effects.

Levels of 90Nb excited via the 90Zr(p, nγ) reaction

Abstract The excitation functions of the 90Zr(p, nγ) reaction have been measured with a Ge(Li) detector to investigate the low-lying levels of 90Nb and their γ-decay. The incident proton energy was varied from 6.90 to 9.50 MeV in steps of 100 keV. Thirty-four levels in 90Nb which include those of the predominant [(1 g 9 2 ) π (1 g 9 2 ) ν − ] Jπ = 2 + − 8 + and [(2 p 1 2 ) π (1 g 9 2 ) ν −1 ] jπ = 4 − , 5 − configurations have been confirmed. A level with a predominant [(1 g 9 2 ) π (1 g 9 2 ) ν −1 ] 1+ configuration is also suggested. The decay scheme of 90Mo has been revised.

Line broadening and Coulomb displacement energies of the hole-state analogs in the A = 111−123 odd-mass Sn isotopes

Abstract Line broadening and orbit dependence of the Coulomb displacement energy have been observed for the 1g 9/2 , 2p 1/2 and 2p 3/2 hole-state analogs in a series of odd- A Sn isotopes. The observed widths are discussed in terms of spreading width with main contributions from mixing with the isovector monopole state as well as the escape width.

An Upper Limit for the Mass of the Electron Anti-neutrino From the Ins Experiment

Abstract The β-spectrum in 3 H decay has measured at INS with an energy resolution of 10–16 eV. The overall response function of the spectrometer system was reliably obtained with a reference 109 Cd source having the same chemical structure as the 3 H source. An upper limit of 32 eV has been obtained for the mass of the electron anti-neutrino with statistical and systematic errors.

The 1p neutron pick-up strengths in the reaction 13C(p, d) 12C

Abstract Excited states up to about 18 MeV in 12 C have been investigated with the 13 C(p,d) 12 C reaction. It was found that five states (ground, 0 + , T =0; 4.43 MeV, 2 + , T =0; 12.71 MeV, 1 + , T =0; 15.11 MeV, 1 + , T =1 and 16.11 MeV, 2 + , T =1 almost exhaust the available pick-up strength. Spectroscopic factors for these states extracted from a DWBA analysis with the usual separation energy procedure gave good agreement with the prediction of the effective interaction calculation by Cohen and Kurath.

Systematic observation of fine structure of the hole-state analogues in Ni isotopes

Abstract Using (p, d) reactions, fine structure of the ground hole-state anlogues in 57, 61, 63 Ni has been investigated with a magnetic spectrograph. The systematic variation of the spectra, including the 59 Ni data in our previous measurement, is interpreted in terms of isospin mixing. It is inferred that the most important contribution to the spreading width comes from the isovector monopole state in these nuclei.

Precise measurement of Ag KLL Auger-spectrum

Abstract The Ag KLL Auger spectrum has been measured with an energy resolution of 8 eV. The energies and the intensities of all nine lines are precisely determined with 1–2 orders of magnitude better accuracies than those in the previous experiment. The data obtained are found to be in good agreement with the theoretical calculations.