Dissipative collisions of heavy ions at energies close to the Coulomb barrier

Rehm, K. E.; Essel, H.G.; Sperr, P.; Hartel, K.; Kienle, P.; Körner, H. J.; Segel, R. E.; Wagner, W.

doi:10.1016/0375-9474(81)90524-8

Cited by 26 publications

(5 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The most striking feature of the data is the large reduction in the deep-inelastic product cross section for the lowest energy bin. Large reductions in the mass and charge diffusion at near-barrier energies have previously been reported [28,38,39]. Moreover, in contrast to experiments at higher bombarding energies, studies at near-barrier energies have revealed evidence [39] for a strongly nonlinear evolution of the mass and charge variances as a function of the interaction time.…”

Section: Bombarding Energy Dependence Of the Deep-inelastic Product Dmentioning

confidence: 89%

See 1 more Smart Citation

Reexamining the heavy-ion reactions238U+238U and238U+
Kratz
¹
,
Schädel
²
,
Gäggeler
³

2013
Phys. Rev. C

View full text Add to dashboard Cite

Recent theoretical work has renewed interest in radiochemically determined isotope distributions in reactions of 238 U projectiles with heavy targets that had previously been published only in parts. These data are being reexamined. The cross sections σ (Z) below the uranium target have been determined as a function of incident energy in thick-target bombardments. These are compared to predictions by a diffusion model whereby consistency with the experimental data is found in the energy intervals 7.65-8.30 MeV/u and 6.06-7.50 MeV/u. In the energy interval 6.06-6.49 MeV/u, the experimental data are lower by a factor of 5 compared to the diffusion model prediction indicating a threshold behavior for massive charge and mass transfer close to the barrier. For the intermediate energy interval, the missing mass between the primary fragment masses deduced from the generalized Q gg systematics including neutron pair-breaking corrections and the centroid of the experimental isotope distributions as a function of Z have been used to determine the average excitation energy as a function of Z. From this, the Z dependence of the average total kinetic-energy loss (TKEL) has been determined. This is compared to that measured in a thintarget counter experiment at 7.42 MeV/u. For small charge transfers, the values of TKEL of this work are typically about 30 MeV lower than in the thin-target experiment. This difference is decreasing with increasing charge transfer developing into even slightly larger values in the thick-target experiment for the largest charge transfers. This is the expected behavior which is also found in a comparison of the partial cross sections for quasielastic and deep-inelastic reactions in both experiments. The cross sections for surviving heavy actinides, e.g., 98 Cf, 99 Es, and 100 Fm indicate that these are produced in the low-energy tails of the dissipated energy distributions, however, with a low-energy cutoff at about 35 MeV. Excitation functions show that identical isotope distributions are populated independent of the bombarding energy indicating that the same bins of excitation energy are responsible for the production of these fissile isotopes. A comparison of the survival probabilities of the residues of equal charge and neutron transfers in the reactions of 238 U projectiles with either 238 U or 248 Cm targets is consistent with such a cutoff as evaporation calculations assign the surviving heavy actinides to the 3n and/or 4n evaporation channels.

show abstract

Section: Bombarding Energy Dependence Of the Deep-inelastic Product Dmentioning

confidence: 89%

“…III A3, large reductions of mass and charge diffusion at near-barrier energies were also reported in Refs. [28,38,39].…”

Section: Comparison Of the Element Yields In The 238 U + 238 U/ 2mentioning

confidence: 99%

Reexamining the heavy-ion reactions238U+238U and238U+
Kratz
¹
,
Schädel
²
,
Gäggeler
³

2013
Phys. Rev. C

View full text Add to dashboard Cite

show abstract

“…(5). For the second term, which describes the nuclear contact phase of the collision, we use a phenomenological trajectory designed to span the widest possible range of realistic trajectories by using as few free parameters as possible.…”

Section: Ternary Dissipative U+au Collisionsmentioning

confidence: 99%

“…the impact parameter from the energy loss. Unfortunately, this is only possible on average since the direct connection between the entrance and exit channel is destroyed by statistical fluctuations, particularly in central collisions for which the energy loss is highest and for which the longest contact times are predicted [4,5].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the dynamics of dissipative U+Au collisions with δ-electron spectroscopy

Stroth

Backe

Begemann-Blaich

et al. 1997

Z Phys A - Particles and Fields

View full text Add to dashboard Cite

δ-electron emission in elastic and dissipative collisions of U+Au at E/A = 8.65 MeV has been investigated. The velocity vectors of the reaction products were measured in coincidence with electrons of energies up to 3.2 MeV. The δ-electron yield measured for elastic collisions is in good agreement with coupled-channels calculations. The δ-electron spectra of dissipative reactions show a clear dependence on the violence of the collision, i.e. the total kinetic energy loss (TKEL). The shape of the spectra are analysed with an atomic model by a fitting procedure using phenomenological trajectories. The results indicate an increasing contact time of the united system with increasing total kinetic energy loss reaching 1.16(4) × 10 −21 s at < T KEL > = 375 MeV.

show abstract

“…This type of contamination would be most serious for the most out-of-plane spectrum because the average lab energy of the main component drops to only 15 MeV above the threshold, making it difficult to identify a still lower energy contaminant. The calculated shape of the a-particle out-of-plane angular distribution is quite sensitive to the parameters Imax and K~ but is insensitive to the other parameters.…”

Section: Alpha Particle Emission Sourcementioning

confidence: 99%

Alpha-particle emission from the reaction 1354 MeVHo165+Ta
Sobotka
¹
,
McDonald
²
,
Wozniak
³

et al. 1983
Phys. Rev. C
7
0
2
0
View full text Add to dashboard Cite

The emission of a particles from the deep-inelastic reaction 1354 MeV 165 Ho + 181 ra has been studied. Alpha particles were detected in coincidence with a projectile-like fragment, both in and out of the reaction plane. Average velocity diagrams, a-particle energy spectra as a function of angle, and a-particle angular distributions are presented. The in-plane data show that the bulk of·the a particles in coincidence with the deep-inelastic exit channel can be explained by evaporation from the fully accelerated fragments. The o~t-of-~lane a-particle angular distribution data together with gamma-ray multiplicity data from previous work give a consistent picture of the transfer and partitioning of angular momentum between the two fragments./NUCLEAR REACTIONS 181 ra ( 165 Ho, HI a)ELab = 1354 MeV: measured a (E ,g ,0 ), in-and out-of-plane anisotropies: a a a a deduced a-particle multiplicity, nuclear temperature.

show abstract

Dissipative collisions of heavy ions at energies close to the Coulomb barrier

Cited by 26 publications

References 40 publications

Reexamining the heavy-ion reactions238U+238U and238U+
Kratz
¹
,
Schädel
²
,
Gäggeler
³

2013
Phys. Rev. C

Reexamining the heavy-ion reactions238U+238U and238U+
Kratz
¹
,
Schädel
²
,
Gäggeler
³

2013
Phys. Rev. C

Investigation of the dynamics of dissipative U+Au collisions with δ-electron spectroscopy

Alpha-particle emission from the reaction 1354 MeVHo165+Ta
Sobotka
¹
,
McDonald
²
,
Wozniak
³

et al. 1983
Phys. Rev. C
7
0
2
0
View full text Add to dashboard Cite

Contact Info

Product

Resources

About

Dissipative collisions of heavy ions at energies close to the Coulomb barrier

Cited by 26 publications

References 40 publications

Reexamining the heavy-ion reactions238U+238U and238U+Kratz1, Schädel2, Gäggeler3 2013Phys. Rev. C

Reexamining the heavy-ion reactions238U+238U and238U+Kratz1, Schädel2, Gäggeler3 2013Phys. Rev. C

Investigation of the dynamics of dissipative U+Au collisions with δ-electron spectroscopy

Alpha-particle emission from the reaction 1354 MeVHo165+TaSobotka1, McDonald2, Wozniak3 et al. 1983Phys. Rev. C7020View full textAdd to dashboardCite

Contact Info

Product

Resources

About

Reexamining the heavy-ion reactions238U+238U and238U+
Kratz
¹
,
Schädel
²
,
Gäggeler
³

2013
Phys. Rev. C

Reexamining the heavy-ion reactions238U+238U and238U+
Kratz
¹
,
Schädel
²
,
Gäggeler
³

2013
Phys. Rev. C

Alpha-particle emission from the reaction 1354 MeVHo165+Ta
Sobotka
¹
,
McDonald
²
,
Wozniak
³

et al. 1983
Phys. Rev. C
7
0
2
0
View full text Add to dashboard Cite