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Andersen, J. U.; Chevallier, J.; Forster, J.S.; Karamian, S. A.; Vane, C. R.; Beene, J. R.; Galindo-Uribarri, A.; Campo, J. Gómez del; Krause, H. F.; Padilla‐Rodal, E.; Radford, D. C.; Broude, C.; Malaguti, F.; Uguzzoni, A.

doi:10.1103/physrevlett.99.162502

Cited by 31 publications

(21 citation statements)

References 20 publications

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“…However, it was too time consuming to record mask spectra with fission fragments and instead the calibration for the simultaneously recorded elastic scattering was applied as in earlier work [24,25]. We found in the present analysis that one then must correct for the different depth profiles of energy deposition in the counter.…”

Section: Discussionmentioning

confidence: 91%

“…In our previous work [24], we observed that the y signal depends on the mass of the detected particle, and we scaled the y-coordinate for the fissions so that the axis of the fission and elastic blocking patterns occurred at the same y-coordinate. In the first analysis of the present data [25], we refined this correction and introduced a linear dependence of this y-scaling on the parameter E rest , ensuring that the coordinates of the center of the blocking dip were the same for all fission fragments as those for the elastics.…”

Section: Discussionmentioning

confidence: 99%

“…However, in a preliminary publication of a small selection of the present data we applied a more sophisticated analysis and found strong effects of fission delay, even for 32 S bombardment. Lifetimes of order 2 as were deduced [25]. The key to the interpretation was an analysis of the shape of the blocking dips, with a comparison between the blocking of fission fragments and of elastically scattered ions which took into account an angular smearing due to mosaic structure of the thin target crystals.…”

Section: Introductionmentioning

confidence: 99%

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Attosecond time delays in heavy-ion induced fission measured by crystal blocking

et al. 2008

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The time delays in fission induced by bombardment of W with 180 MeV 32 S, 240-255 MeV 48 Ti, 330-375 MeV 58 Ni, and 390 MeV 74 Ge have been measured by observation of crystal blocking. Nearly all results are consistent with exponential decay with lifetimes of order 10 −18 s which depend weakly on the atomic number of the composite nucleus. This is inconsistent with the Bohr-Wheeler model of fission from a compound nucleus in statistical equilibrium at each stage in a neutron evaporation cascade and supports a picture of strongly damped quasifission. A simple diffusion model with one-body dissipation reproduces roughly the observed time scale and the exponential decay. It suggests that the outer fission barrier could play a significant role in the observed, very slow decays.

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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Attosecond time delays in heavy-ion induced fission measured by crystal blocking

et al. 2008

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“…However direct measurements by X-ray and crystal blocking techniques have shown very long fission delay times (∼10 -18 sec) even for the highly excited uranium-like and trans-uranium nuclei [16][17][18]. These results have not so far been explained by the viscosity effect.…”

Section: Classical Fission Delay Due To Nuclear Viscositymentioning

confidence: 99%

Nuclear temperatures from evaporation fragment spectra and observed anomalies

Ray

Chatterjee

et al. 2013

Phys. Rev. C

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Abstract. The extreme back-angle evaporation spectra of alpha, lithium, beryllium, boron and carbon from different compound nuclei near A ≈100 (E X = 76 -210 MeV) have been compared with the predictions of standard statistical model codes such as 'CASCADE' and 'GEMINI'. It was found that the shapes of the alpha spectra agree well with the predictions of the statistical models. However the spectra of lithium, beryllium, boron and carbon show significantly gentler slopes implying higher temperature of the residual nuclei, even though the spectra satisfy all other empirical criteria of statistical emissions. The observed slope anomaly was found to be largest for lithium and decreases at higher excitation energy. These results could not be understood by adjusting the parameters of the statistical models or from reaction dynamics and might require examining the statistical model from a quantum mechanical perspective.

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“…These times have to be compared with fusion-fission times which can be longer than 10 −16 s [9]. This shows that the two mechanisms are of very different nature.…”

Section: Introductionmentioning

confidence: 99%

Effects of nuclear structure on quasi-fission

Simenel

Wakhle

Avez

et al. 2012

EPJ Web of Conferences

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Abstract. The quasi-fission mechanism hinders fusion of heavy systems because of a mass flow between the reactants, leading to a re-separation of more symmetric fragments in the exit channel. A good understanding of the competition between fusion and quasi-fission mechanisms is expected to be of great help to optimize the formation and study of heavy and superheavy nuclei. Quantum microscopic models, such as the time-dependent Hartree-Fock approach, allow for a treatment of all degrees of freedom associated to the dynamics of each nucleon. This provides a description of the complex reaction mechanisms, such as quasi-fission, with no parameter adjusted on reaction mechanisms. In particular, the role of the deformation and orientation of a heavy target, as well as the entrance channel magicity and isospin are investigated with theoretical and experimental approaches.

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Crystal Blocking Measurements of the Time Delay of Fission Induced byS32,Ti48, and
J. U. Andersen
¹
,
J. Chevallier
²
,
J.S. Forster
³

et al.

Cited by 31 publications

References 20 publications

Attosecond time delays in heavy-ion induced fission measured by crystal blocking

Attosecond time delays in heavy-ion induced fission measured by crystal blocking

Nuclear temperatures from evaporation fragment spectra and observed anomalies

Effects of nuclear structure on quasi-fission

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Crystal Blocking Measurements of the Time Delay of Fission Induced byS32,Ti48, andJ. U. Andersen1, J. Chevallier2, J.S. Forster3 et al.

Cited by 31 publications

References 20 publications

Attosecond time delays in heavy-ion induced fission measured by crystal blocking

Attosecond time delays in heavy-ion induced fission measured by crystal blocking

Nuclear temperatures from evaporation fragment spectra and observed anomalies

Effects of nuclear structure on quasi-fission

Contact Info

Product

Resources

About

Crystal Blocking Measurements of the Time Delay of Fission Induced byS32,Ti48, and
J. U. Andersen
¹
,
J. Chevallier
²
,
J.S. Forster
³

et al.