J. Kliman

Background elimination methods for multidimensional coincidence γ-ray spectra

Abstract In the paper new methods to separate useful information from background in one, two, three and multidimensional spectra (histograms) measured in large multidetector γ-ray arrays are derived. The sensitive nonlinear peak clipping algorithm is the basis of the methods for estimation of the background in multidimensional spectra. The derived procedures are simple and therefore have a very low cost in terms of computing time.

Efficient one- and two-dimensional gold deconvolution and its application to γ-ray spectra decomposition

Abstract The use of deconvolution operation makes it possible to improve the resolution in γ-ray spectra. The paper describes a non-oscillating method of Gold deconvolution. The method is generalized for multidimensional spectra. A new optimized algorithm of one- and two-dimensional Gold deconvolution aimed to reduce number of computer operations has been derived in the paper.

Identification of peaks in multidimensional coincidence γ-ray spectra

Abstract In the paper a new algorithm to find peaks in two, three and multidimensional spectra, measured in large multidetector γ-ray arrays, is derived. Given the dimension m, the algorithm is selective to m-fold coincidence peaks. It is insensitive to intersections of lower-fold coincidences, hereinafter called ridges.

New Spontaneous Fission Mode for 252Cf: Indication of Hyperdeformed 144,145,146Ba at Scission.

From {gamma}-ray coincidence studies following spontaneous fission of {sup 252}Cf, direct measurements of yields and neutron multiplicities were made for Sr-Nd, Zr-Ce, Mo-Ba, Ru-Xe, and Pd-Te correlated pairs. A strong enhancement of the 7-10 neutron channels for Mo-Ba pairs is observed. A new fission mode associated with the enhanced neutron yields is identified. These data can be interpreted in terms of one or more of {sup 144,145,146}Ba being hyperdeformed at scission. Mean field calculations predict a hyperdeformed third minimum in {sup 252}Cf and an extremely deformed {sup 146}Ba fragment at scission. {copyright} {ital 1996 The American Physical Society.}

Integrated multiparameter nuclear data analysis package

Abstract A modular system to realize measurements along with analysis, processing and visualization of acquired data is described. Besides standard methods also new developed algorithms of data processing have been included in the system.

The 270 MeV deuteron beam polarimeter at the Nuclotron Internal Target Station

A deuteron beam polarimeter has been constructed at the Internal Target Station at the Nuclotron of JINR. The polarimeter is based on spin-asymmetry measurements in the d − p elastic scattering at large angles and the deuteron kinetic energy of 270 MeV. It allows to measure vector and tensor components of the deuteron beam polarization simultaneously.

High-spin states in neutron-rich even-even Pd isotopes

Transitions among high-spin states in 112,114,116Pd are observed through prompt -ray spectroscopy following the spontaneous fisson of 252Cf. Spins and parities are assigned to many newly observed levels based on angular correlation analysis and comparison with known spins and parities of less neutron-rich Pd nuclides. The -band structures are significantly extended. New rotational band structures are observed for the first time, and tentatively assigned negative parity. IBA-1 model calculations are performed for the ground state and -bands.

New data on the ternary fission of 252Cf from the Gammasphere facility

Ternary fission of 252Cf was studied at Gammasphere using eight ΔE×E particle telescopes. Helium, beryllium, boron, and carbon light charged particles (LCPs) emitted with kinetic energy more than 9, 21, 26, and 32 MeV, respectively, were identified. The 3368-keV γ transition from the first 2+ excited state in 10Be was found and the population probability ratio N(2+)/N(0+) = 0.160 ± 0.025 was estimated. No evidence was found for 3368-keV γ rays emitted from a triple molecular state. For the first time, charge distributions are obtained for ternary fission fragments emitted with helium, beryllium, and carbon LCPs.

Optimized multidimensional nonoscillating deconvolution

The paper presents a nonoscillating iterative method of Gold deconvolution. The method is generalized for multidimensional data. From computational point of view the Gold deconvolution is time-consuming operation. It requires a great number of numerical operations. A new optimized algorithm aimed to reduce number of computer operations has been derived in the paper.

Structure of neutron-rich nuclei and neutron multiplicities in spontaneous fission

Abstract New insights into the fission process and the structure of neutron-rich nuclei have been gained by measuring γ-γ and γ-γ-γ coincidences of the prompt γ-rays following the spontaneous fission of 252Cf. The data were taken with the Compton Suppression Spectrometer System at HHIRF. New high spin levels were observed in 143,145,147Ba Only in 143Ba are intertwined bands observed with the characteristics of the octupole structure found only in 144Ba. New high spin states observed in the N = 84 136 Te, 138 Xe, 140 Ba nuclei exhibit a symmetry pattern suggestive of a pseudospin f - shell . For the first time in fission, the relative yields and neutron multiplicities were measured directly. Yields and multiplicities were measured directly for the ZrCe and MoBa correlated fragment pairs by observing the coincidences between the γ-rays in each fragment. Zero-neutron to ten-neutron emission yields were determined; the latter for the first time. The zero-neutron emission can be understood as a new example of cluster radioactivity. These results demonstrate that the use of the high resolution γ-γ-γ coincidence technique employed here for the first time opens up a new approach to the study of the fission process that will provide previously inaccessible details of the process.