Prototype of the Digital Electronics Chain for the GABRIELA Detector Assembly and First Tests

International audienceThis paper describes a digital electronics chain prototype for the GABRIELA detector assembly. The goal of the digital algorithm is to reduce the dead time of the electronics to tens of nanoseconds without loss of energy and time resolution. The structure and temporal diagrams of the algorithm are given in the text. The paper also shows the energy resolution of the algorithm in comparison with the existing analog system and the results of the first in beam run

The emission of prompt neutrons from the spontaneous fission of No-252 and Fm-244

The neutron detector with (3)He -filled counters placed in the focal plane of the VASSILISSA separator is used for measuring the average number and determining the multiplicity distribution of prompt neutrons from the spontaneous fission of heavy short-lived isotopes. The test reaction is used for tuning the separator settings and calibrating the detector system with the spontaneous fission of the (252)No . The average neutron number per (252)No spontaneous fission event is as large as . The short-lived heavy isotope (244)Fm , produced in the complete fusion reaction (40)Ar + (206)Pb , is investigated. The average number of neutrons per spontaneous fission of (244)Fm from the experimental data ( is determined for the first time

Digital Signal Processing for the GABRIELA Detector Assembly

International audienceThis paper briefly describes the main ways of digital signal processing. The goal of the digital algorithms is to reduce the dead time of the spectrometry path to tens of nanoseconds without loss of energy and time resolutions. The new kσ-trigger with extrapolation technique is proposed in the paper. The method allows to find overlapped signals almost irrespective of their closeness in time

Investigation of isomeric states in <math><mmultiscripts><mi>Rf</mi><mprescripts/><none/><mn>255</mn></mmultiscripts></math>

International audienceUsing the GABRIELA detector array, γ-ray and internal-conversion-electron decay spectroscopy has been performed on Rf255 nuclei that were produced via the Pb207(Ti50,2n)Rf255 fusion-evaporation reaction using the SHELS velocity filter. Three isomers were identified in Rf255 with the aid of Geant4 simulations. The existence of two high-K isomeric states in cascade has been confirmed. Possible three-quasiparticle configurations involving the coupling of the unpaired 9/2−[734] neutron to two-quasiparticle states have been suggested and a likely decay scenario has been proposed on the basis of comparisons to Geant4 simulations. The simulations have also confirmed the existence of the 5/2+[622] spin isomer at low excitation energy

Spontaneous Fission of 256^{256}Rf, New Data

International audienceSpontaneous fission properties of the short-lived neutron-deficient 256Rf nucleus produced in thecomplete fusion reaction with a beam of multiply charged heavy 50Ti ions from the U-400 cyclotron (FLNR,JINR) are experimentally investigated. Its half-life and decay branching ratio are measured. The averagenumber of neutrons per spontaneous fission of 256Rf ( = 4.47 ± 0.09) is determined for the first time