Search results for "nuclear fusion"
showing 10 items of 437 documents
Evidence for quasi-fission in40Ar+208Pb collisions near the coulomb-barrier
1987
Fission-fragment angular distributions were measured in the reaction of40Ar with208Pb near the fusion barrier. For nearly symmetric mass-/charge splits we find angular distributions symmetric around θ=90 degrees, however, with unusually large anisotropies. These develop gradually into forward-backward asymmetric distributions as one moves away from mass-/charge symmetry. This indicates that non-compound fission (‘quasi-fission’) competes with true fusion-fission. The relative contribution of quasi-fission to the total fission cross section is somewhere between 51 and 85%. In the framework of the extra-push model this is equivalent to an extra-extra push energy for compound-nucleus formation…
Beta-decay of148,150,152Pr into levels of148,150,152Nd
1988
Theβ−-decay of148,150,152Pr into levels of148,150,152Nd has been studied byγ-singles,γγ-coincidence and for148Pr also byγγ-angular correlation measurements. The praseodymium activities have been obtained by thermal neutron-induced fission of235U followed by on-line mass separation with the helium-jet coupled mass separator HELIOS. Decay schemes for these heaviest praseodymium nuclides are proposed. From the angular correlation measurements spin values for the seven lowest levels of148Nd are deduced. Spin and parity assignments for the lower levels in150,152Nd have been extrapolated from level systematics.
Tritium retention in plasma facing materials of JET ITER-Like-Wall retrieved from the vacuum vessel in 2012 (ILW1), 2014 (ILW2) and 2016 (ILW3)
2021
Abstract ITER-Like-Wall (ILW) project has been carried out at Joint European Torus (JET) to test plasma facing materials relevant to International Thermonuclear Experimental Reactor – ITER [1]. Limiters and an upper dump plate of the vacuum vessel are made of bulk beryllium tiles, whereas for the divertor bulk tungsten and tungsten-coated carbon fibre (CFC) composite tiles are used. During the shutdowns in ILW1 (2012), ILW2 (2014) and ILW3 (2016), selected beryllium tiles were removed from the vacuum vessel. In this study, tiles from three positions were analysed, and analysis results were compared regarding both the tile position in the vacuum vessel and differences in the exploitation con…
The charge radii of $^{198}$Pt - $^{183}$Pt
1989
The changes of the mean-square charge radii have been measured for198Pt-183Pt by means of resonance ionization mass spectroscopy (RIMS) at the new on-line isotope separator ISOLDE-3/CERN. As in the case of the neighbouring isotopes of Au and Hg, a strong nuclear deformation of ¦β2¦ −-0.24 is reached at the neutron mid-shell nucleus183Pt, but no indication for a sharp shape transition is observed from the study of the isotope shifts.
Reactions of40Ar with233U,235U, and238U at the barrier
1990
Production cross sections for target-like transfer products in reactions of40Ar with233,235,238U at the barrier were determined using radiochemical techniques. The heaviest products detected are isotopes of californium (Z=98). In addition to the quasi-elastic component of the isotopic distributions observed in the vicinity of uranium, there are also relaxed contributions throughout the entire region. The peak positions of the isotope distributions of this component for fixed atomic number, after the transfer of > 3 charges, approach closely the minimum of the potential energy surfaces (PES). The experimental results thus indicate the cold formation of the reaction products. A search for lon…
High-spin bands in117,119I and118Xe
1984
Excited states in117I,118Xe and119I were populated in the reactions106Pd+16O and108, 110Cd+12C. The groundstate band in118Xe was observed to its (18+) member and the 11/2− bands in117I and119I to their (35/2−) and (43/2−) members, respectively. The structure of the bands in the I isotopes is interpreted as aπ h11/2 proton coupled to an even-even band structure in Xe, and the band crossings observed in118Xe and119I are interpreted in the Cranked Shell Model framework asABn ofv h11/2.
Untersuchung der Feldelektronenemission und ihrer Temperaturabh�ngigkeit bei Stromst�rken zwischen 10?14 und 10?19 A
1964
The field emission of a tungsten point cathode at very low emission currents was investigated by means of a secondary emission multiplier. The validity of the Fowler-Nordheim equation was experimentally confirmed within the range from 10−8 to 10−19 A. The dependence of the total emission current on temperature and electrical field strength was measured in the transition region between thermionic and field emission. A comparison is drawn with the theory ofMurphy andGood.
Onset of deformation in neutron-rich krypton isotopes
1988
Beta-decay properties of neutron-rich35Br isotopes confirm the predicted smooth onset of quadrupole deformation for Z<37 already below N=60. The observed increase of the energy of the first 2+ state in the N=56 nucleus92Kr may indicate octupole softness.
Determination of the isotope shift in theD 1 line between197Au and195Au
1983
The isotope shift between197Au (stable) and195Au (T 1/2=183 d) was determined by resonance fluorescence and polarization spectroscopy in the 6s2 S 1/2 -6p 2 P 1/2, λ =267.6nm line. The result is δν195, 197=-2.9(2) GHz corresponding to a change of the mean-square charge radius by δ〈r 2〉195, 197=0.063(9) fm2. The sample was confined to a resonance cell heated to temperatures of up to 1500°C.
New nuclides: Neptunium-243 and neptunium-244
1987
We have observedγ-rays following the β−-decay of243Np and244Np after chemical isolation of neptunium isotopes from the products of the reaction of 835 MeV136Xe with244Pu. The ground-state of 1.85-min243Np hasJ=5/2. The decay of 2.29-min244Np (probableJπ=7−) populates high-spin members of the ground state rotational band in244Pu.