[en] In in-beam spectroscopy using heavy ion reactions, methods of classification and identification for a large number of gamma rays emitted from many kinds of the compound nuclei have been established by utilizing multiplicity signals of evaporated charged particles. In studies of the last decade, firstly a six segmented Si Δ E detector system and next, Si Ball covering whole solid angle subtended for a target were constructed. These construction and performance are presented and a perspective of analyzing system of the charged particle multiplicity is discussed. (author)

[en] Published in summary form only

[en] Decay of mass-separated samples of the nuclide ⁷³Br have been investigated by means of an on-line isotope separator in the Tandem Accelerator Laboratory of Kyushu University. Twenty eight γ-rays were assigned to the decay of ⁷³Br. The half-life was measured to be 3.4±0.2 min. The decay scheme of ⁷³Br was constructed on the basis of γ-ray energies, intensities of γ-rays and conversion electrons, and relations of γγ-, βγ- and γ(ce)-coincidences. Spins and parities of the ten levels of ⁷³Se were assigned or limited according to log ft values, conversion coefficients and branching ratios of the transitions. Systematical trends in the level schemes of N=39 isotones ⁶⁹Zn, ⁷¹Ge, ⁷³Se, ⁷⁵Kr and ⁷⁷Sr are discussed. (orig.)

[en] In studies of in-beam gamma ray spectroscopy for nucleides far from the beta-stability line, it is one of the most important things to know what nucleide emits gamma rays. In order to identify nucleide which emitting the gamma rays, we have proposed a new gamma ray measuring system which consists of an annular type high purity Ge detector, a beam separator, a device for identification of atomic number, and a TOF type mass spectrometer. In order to obtain the best mass resolving power in the TOF type mass spectrometer, characteristic of a Si(Au) detector as the measuring device of particle energy was investigated. For this purpose Si(Au) detectors which can generate strong internal static field were fablicated. The energy resolution for heavy ions of various kind were measured as functions of the detector bias voltage, and the response functions concerning channelling effect were also studied for various incident particles. Many interesting evidence were observed with respect to pulse height defect and radiation damage. From these experimental results, following things were concluded. 1. Strong electric field in the Si(Au) detector is the most important to measure heavy ions in high resolution from the view points of pulse height defect, radiation damage and charge collection. 2. It is found that large disturbance in response function for heavy ions is caused by channelling effect, and then it is concluded that the effect can be reduced completely by inclining 1⁰ incident angle against perpendicular direction of crystalline surface of the detector. (author)

[en] Investigations of the nucleus ⁸²Sr are considered particularly interesting, where very different configurations changing with spin and excitation energy may be observed. The present report describes the high spin band structure of ⁸²Sr deduced from an in-beam study. The experiments presented were carried out at the Niels Bohr Institute tandem accelerator laboratory. High-spin states in ⁸²Sr are populated using the ⁵⁸Ni(²⁸Si,4p)⁸²Sr reaction at a beam energy of 128 MeV. A stacked target of two self-supporting ⁵⁸Ni foils with a thickness of 0.34 mg/cm² is used. Gamma rays are detected in the NORDBALL array of 20 Compton suppressed germanium detector. Neutrons are also measured. Analysis is made of the gamma ray spectrum obtained by summing up spectra in coincidence with gamma rays in the negative parity band, in the odd spin band, in the ground band, or in the yrast band. An energy level scheme of ⁸²Sr is proposed and discussed. The kinematical moment of inertia is calculated and discussed as a function of rotational frequency for the rotational bands in ⁸²Sr. The quantum number K=0 is used in calculating the moment of inertia of the side bands. (N.K.)

[en] In the experiments on ⁷⁴Ge(d,pγ)⁷⁵Ge, a 52.5 +- 0.1 keV γ-ray was found in ⁷⁵Ge with a half-life of 216 +- 5 ns. From the analysis of the γ-ray spectra the conversion coefficient of the 52.5 keV γ-ray was determined. Then, a new level of Jsup(π) = 5/2⁺ is confirmed to exist at 192.5 keV. The reduced transition probabilities of the 52.5 keV transition are deduced to be (6.9⁺⁵.⁶sub(-)₂.₁) x 10^-5 for B(M1) and 31⁺³sub(-)₂ for B(E2) in Weisskopf units. (orig.)

No abstract available

[en] Yttrium-81 with very small fusion cross section was studied using NORDBALL in conjunction with very powerful filters for reaction channel selection. It was proved that Clean-up of γ - γ matrix is very useful to study ⁸¹Y nucleus. Ground state band show a rotational alignment of gq/2 neutrons at a rotational frequency of 0.68 MeV. This alignment is consistent with a neighbouring even-even nucleus of ⁸⁰Sr. (author)

[en] The reactions ⁵⁸Ni(³²S, 3p)⁸⁷Nb were used to populate excited states in ⁸⁷Nb. The deexcitation of these states was studied by in-beam γ-ray spectroscopy. Measurements of (p, α)-γ coincidence, p-γ γ coincidence and γ-ray angular distribution were performed. The level scheme of ⁸⁷Nb up to 6MeV in excitation energy was deduced. Spin and parity of ground state of ⁸⁷Nb were decided from the β-decay study of ⁸⁷Mo. The new decay scheme of ⁸⁷Mo was also deduced. (author)

[en] The report addresses the developement of a 4π-type Si detector array, called Si crystal ball, designed for determination of the multiplicity of charged particles. The design requirements for the detector array are as follows: it should be possible to distinguish between output signals for proton and α particle; the detector system as a whole should be operable up to a counting rate of about 5x10⁵ cps; the vacuum tank containing the detector array and target should be of a size that permits its accommodation in a spherical container with a diameter of 98 mm; the detector system should have a dodecahedron configuration consisting of pentagonal unit detectors; and the incident particles should not enter the detector system to allow heavy ions to damage the system. Each pentagonal unit detector has sides of 18 mm and a thickness of 178 μm. Tests are made to determine the performance of the Si crystal ball. Results show that its detection efficiency is 25 percent for 3p-channel gamma rays gated by 3p and 40 percent for 2p-channel gamma rays gated by 2p, which are about 20 and 10 times as high, respectively, compared to conventional detectors. (N.K.)