The superheavy element with atomic number Z=117 was produced as an evaporation residue in the (48)Ca+(249)Bk fusion reaction at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. The ...radioactive decay of evaporation residues and their α-decay products was studied using a detection setup that allowed measuring decays of single atomic nuclei with half-lives between sub-μs and a few days. Two decay chains comprising seven α decays and a spontaneous fission each were identified and are assigned to the isotope (294)117 and its decay products. A hitherto unknown α-decay branch in (270)Db (Z = 105) was observed, which populated the new isotope (266)Lr (Z = 103). The identification of the long-lived (T(1/2) = 1.0(-0.4)(+1.9) h) α-emitter (270)Db marks an important step towards the observation of even more long-lived nuclei of superheavy elements located on an "island of stability."
Search for elements 119 and 120 Khuyagbaatar, J.; Yakushev, A.; Düllmann, Ch. E. ...
Physical review. C,
12/2020, Volume:
102, Issue:
6
Journal Article
Peer reviewed
Open access
A search for production of the superheavy elements with atomic numbers 119 and 120 was performed in the 50Ti+249Bk and 50Ti+249Cf fusion-evaporation reactions, respectively, at the gas-filled recoil ...separator TASCA at GSI Darmstadt, Germany. Over four months of irradiation, the 249Bk target partially decayed into 249Cf, which allowed for a simultaneous search for both elements. Neither was detected at cross-section sensitivity levels of 65 and 200 fb for the 50Ti+249Bk and 50Ti+249Cf reactions, respectively, at a midtarget beam energy of Elab=281.5 MeV. The nonobservation of elements 119 and 120 is discussed within the concept of fusion-evaporation reactions including various theoretical predictions on the fission-barrier heights of superheavy nuclei in the region of the island of stability.
SnO
2
-based chemoresistive sensors were tested for the detection of H
2
O and CO impurities both before and after exposure to α-particles and γ-rays, assessing their radiation resistance for use in ...moderately radioactive environments. The materials examined were SnO
2
with gold nanoparticles, and a mix of Sn-, Ti-, and Nb-oxides. The performance was evaluated in both an open-ended gas-flow setup and in a gas-loop system. Post-irradiation characterization via scanning electron microscopy and energy-dispersive X-ray spectroscopy was performed to assess morphological changes. Preliminary results showed a fast and efficient response of the sensors after irradiation, indicating their suitability for this novel use.
The analysis of fission events following the implantation of evaporation residues produced in the fusion reaction of 50Ti and 209Bi at different bombarding energies has revealed 5 millisecond decays, ...which are attributed to the spontaneous fission of proton-evaporation channels. The average cross sections for proton evaporation are found to be ∼100 and 10 times smaller than the largest neutron-evaporation channel cross section at the same excitation energy. These results suggest that the proton evaporation channel, albeit weak, may represent a realistic alternative to synthesize new, more neutron rich super heavy nuclei.
The heaviest currently known nuclei, which have up to 118 protons, have been produced in 48Ca induced reactions with actinide targets. Among them, the element tennessine (Ts), which has 117 protons, ...has been synthesized by fusing 48Ca with the radioactive target 249Bk, which has a half-life of 327 d. The experiment was performed at the gas-filled recoil separator TASCA. Two long and two short α decay chains were observed. The long chains were attributed to the decay of 294Ts. The possible origin of the short-decay chains is discussed in comparison with the known experimental data. They are found to fit with the decay chain patterns attributed to 293Ts. The present experimental results confirm the previous findings at the Dubna Gas-Filled Recoil Separator on the decay chains originating from the nuclei assigned to Ts.
The adsorption behavior of
197
Hg and
183–185
Hg on red amorphous selenium (red a-Se) and trigonal selenium (t-Se) was investigated experimentally by off-line and on-line gas chromatographic methods, ...in preparation of a sensitive chemical separation and characterization of the transactinides copernicium (Cn, Z = 112) and flerovium (Fl, Z = 114). Monte-Carlo simulations of a diffusion controlled deposition were in good agreement with the experimental results, assuming as interaction limits −ΔH
ads
red a-Se
(Hg) > 85 kJ/mol, and −ΔH
ads
t-Se
(Hg) < 60 kJ/mol. Both Se allotropes can be used as stationary surfaces in comparative gas-chromatographic chemical investigations of Cn and Fl.
This manuscript reports on the optimization of a molecular plating procedure for the production of uniform and homogeneous films of holmium deposited onto gold-plated copper substrate. In particular, ...the effects caused by molecular plating solvents with different vapour pressure on the morphology and stability of the resulting films were investigated, allowing the selection of the optimum solvent. The developed procedure will allow allow the production of sources of holmium ions for the envisaged HOLMES experiment aiming at the direct measurement of the neutrino mass.
•The neutrino mass direct measurement is a paramount objective in contemporary science.•The utilization of a Ho-163 source plays a pivotal role in neutrino mass measurement.•Successful fabrication of a Ho source was achieved through molecular plating method.
High-temperature performance of solid-state sensors up to 500 °C Weiss, C.; Wilson, J.; Tiebel, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2022, Volume:
1040
Journal Article
Peer reviewed
Open access
The applicabilities of single-crystal chemical vapour deposition diamond sensors and 4H-SiC diodes for particle spectroscopy in high-temperature environments are investigated. The spectroscopic ...performance of the sensor materials is measured as function of temperature, from room temperature to 500 °C. Previously published measurements showed a stable spectroscopic response of sCVD diamond sensors up to 200 °C. In this follow-up experiment, the temperature range was extended up to 500 °C for sCVD diamond as well as 4H-SiC sensors.
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