Investigation of the velocity distribution of evaporation residues produced in20Ne+197Au reactions atE/A=5.7?11.4 MeV/u

Heßberger, F. P.; Ninov, V.; Spoerel, U.

doi:10.1007/bf01303829

Cited by 12 publications

(8 citation statements)

References 27 publications

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“…Further details on the experimental set-up as well as data aquisition and analysis are given in [13,19]. Typical a-spectra, observed in our experiments, are shown in Fig.…”

Section: H Experimentsmentioning

confidence: 98%

“…The velocity of particles able to pass it, is given by the E/Bratio. So, for a beam of particles having any velocity distribution, the latter one can be scanned just by measuring the particle rates at different E/B-ratios (see [13] for further details).…”

Section: Iii1 Velocity Distributionsmentioning

confidence: 99%

“…In addition to residues from complete fusion reactions a contribution, connected to the emission of fast, light particles, emitted in forward direction before reaching thermal equilibrium, was registered [ 13]. It was suspected, that the compoundlike nuclei, leading to these residues, were produced with angular momenta l>I 40 h. Qualitatively, this interpretation is supported by the sum-rule model, which predicts high angular momenta for nuclei produced in incomplete fusion of 160 + 197Au, after break-up of the projectile 2~ into 160 ~-4He.…”

Section: Introductionmentioning

confidence: 99%

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?Slow? residues observed in the reaction20Ne+208Pb at E/A=8.6, 11.4 and 15.0 MeV/u

Heßberger

Ninov

Hofmann

et al. 1994

Z. Physik A - Hadrons and Nuclei

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Abstract. Velocity distributions of heavy residues ARes>Atar, ZRe s>Zta r identified by means of c~ spectroscopy, have been investigated at the velocity filter SHIP in reactions 2~ +2~ at projectile energies E/ A=8.6, 11.4 and 15.0MeV/u. Besides products from complete or nearly complete fusion, characterized by velocity distributions peaking at V/VcN~0.8-1.O, heavy residues with mean velocities of about half of the compound nucleus velocity were observed. The Z-distribution of this component was found to peak at Z = 87. It is interpreted as residues from fusion of target nuclei with projectile fragments produced by nearly symmetric break-up. The experimental results were compared with predictions of theoretical models: cross sections for incomplete fusion were calculated using the sum-rule model of Wilcynski et al., while residue cross sections were calculated using the evaporation code HIVAP. A fair agreement between experimental and calculated mass distributions of heavy residues and transferred projectile fragments is achieved if an energy dissipation of -~ 23 % (at E/A = 8.6 MeV/u) and ~ 8% (at E/A = 11.4 MeV/u) of the incident projectile energy is introduced. The observed peak of the Z-distribution at Z = 87 is predominantly effected due to a higher fission probability of products with Z>87 during the deexcitation process and experimental limitations in the identification of products with Z < 86 by means of ~ spectroscopy, which cause a decrease of the observed production rates towards lower Z.

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“…Further details on the experimental set-up as well as data aquisition and analysis are given in [13,19]. Typical a-spectra, observed in our experiments, are shown in Fig.…”

Section: H Experimentsmentioning

confidence: 98%

Section: Iii1 Velocity Distributionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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?Slow? residues observed in the reaction20Ne+208Pb at E/A=8.6, 11.4 and 15.0 MeV/u

Heßberger

Ninov

Hofmann

et al. 1994

Z. Physik A - Hadrons and Nuclei

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“…Besides registration of the incoming evaporation residues, the 'stop detector' was used to measure the α -decay energies of the implanted nuclei. The energy resolution of the individual strips varied between (15)(16)(17)(18)(19) keV (FWHM) for α particles in the range (5)(6)(7)(8) MeV. The second detector ('light particle detector' (LPD)), an array of 3 × (24×24) mm 2 passivated ion implanted silicon chips of 300 µm thicknesses, was used to detect high energetic light particles that passed SHIP and also the 'stop detector' and could pretent evaporation residues or α decays due to their energy loss in the 'stop detector'.…”

Section: Experimental Set-upmentioning

confidence: 99%

“…In recent experiments we have investigated the production of heavy residues in bombardments of 197 Au (at 114, 172 and 228 MeV) and 208 Pb (at 172, 228 and 298 MeV) with 20 Ne [5,6,7,8]. Significant contributions of incomplete fusion to the heavy residue production, indicated by a shift of the mean velocity of the residues to values vm/vCN ≈ 0.90 -0.95, was observed already at a bombarding energy of 172 MeV, which were interpreted as due to 'incomplete fusion'.…”

Section: Introductionmentioning

confidence: 99%

Evaporation Residue Production in Complete and Incomplete Fusion Reactions of Ne-20 with Au-197 and Ho-165 at E = 14.9 x AMeV

Heßberger¹

2022

Preprint

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Velocity distributions of heavy residues (Ares > Atar), produced in irradiations of 197 Au and 165 Ho with 20 Ne at bombarding energies of E = 208 MeV, have been measured at the velocity filter SHIP. While for the products from 20 Ne + 165 Ho just a mean value of v/vCN = 0.91±0.01 was obtained, individual residues, attributed to isotopes of astatine and polonium with mass numbers ranging from A = 195 to A = 203 could be identified by means of α spectroscopy in the bombardments of 197 Au. A linear increase of the mean velocity from v/vCN ≈ 0.85 to v/vCN ≈ 0.93 with decreasing residue mass was observed. This effect was attributed to an increasing contribution of pre-equilibrium particle emission to the production of heavy residues. A quantititative estimation resulted in a 90% contribution of preequilibrium processes to the production of astatine isotopes, and a 50% contribution to the polonium isotopes.

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Incomplete Fusion in Nucleus-Nucleus Collisions at Intermediate Energies

Magda

Alexander

1994

NATO ASI Series

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Investigation of the velocity distribution of evaporation residues produced in20Ne+197Au reactions atE/A=5.7?11.4 MeV/u

Cited by 12 publications

References 27 publications

?Slow? residues observed in the reaction20Ne+208Pb at E/A=8.6, 11.4 and 15.0 MeV/u

?Slow? residues observed in the reaction20Ne+208Pb at E/A=8.6, 11.4 and 15.0 MeV/u

Evaporation Residue Production in Complete and Incomplete Fusion Reactions of Ne-20 with Au-197 and Ho-165 at E = 14.9 x AMeV

Incomplete Fusion in Nucleus-Nucleus Collisions at Intermediate Energies

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