Effect of collective enhancement in level density in the fission of pre-actinides

Banerjee, Tathagata; Nath, S.; Jhingan, A.; Saneesh, N.; Kumar, Mohit; Yadav, Abhishek; Kaur, Gurpreet; Dubey, R.; Shareef, M.; Laveen, P. V.; Shamlath, A.; Shaikh, Md. Moin; Biswas, S.; Gehlot, J.; Golda, K. S.; Sugathan, P.; Pal, Santanu

doi:10.1103/physrevc.96.014618

Cited by 9 publications

(9 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is a consequence of lowering of the average excitation energy of the ERs since they carry larger angular momentum in SM calculations with dissipation. We further observe that SM predictions match experimental data reasonably well for both proton and α-particle multiplicities from the reactions 32 S + 126 Te, 28 Si + 165 Ho, and 19 F + 181 Ta. However, while close agreement with experimental data is observed for proton multiplicity, the α multiplicity is underestimated to some extent for the systems 16 O + 197 Au and 16 O + 208 Pb when dissipation is included in SM calculation.…”

Section: -5supporting

confidence: 69%

“…The fission probability of CN has no direct effect on particle multiplicities from ERs except influencing the ER angular momentum distribution and, consequently, the excitation energy available for evaporation. We therefore find that the multiplicity distributions obtained with or without dissipation are very close to each other for the systems 32 S + 126 Te, 28 Si + 165 Ho, and 19 F + 181 Ta since the ER excitation functions of the respective systems obtained with or without dissipation are also close. On the other hand, charged particle multiplicities for the systems 16 O + 197 Au and 16 O + 208 Pb are significantly reduced and σ ER are substantially increased when dissipation is included in the SM calculations.…”

Section: -5supporting

confidence: 55%

“…α pre for the 28 Si + 197 Au, SM results obtained without dissipation fit experimental π pre reasonably well for 19 F + 181 Ta, 19 F + 197 Au, and 28 Si + 197 Au systems. Moreover, inclusion of dissipation though improves SM results for α pre for the 16 O + 197 Au and 19 F + 197 Au, they still considerably underestimate the experimental values.…”

Section: -5supporting

confidence: 53%

“…A shorter version of the results obtained from SM calculations with the aforementioned effects has been reported earlier [2]. Fission cross sections for a few systems were also obtained using the same methodology in a previous publication [28]. Here we present results for a larger set of systems and for a wider range of experimental observables.…”

Section: Introductionmentioning

confidence: 72%

“…Quantitative comparison of SM predictions with experimental data, however, does not show any definite pattern. While SM calculation with dissipation gives good fit to experimental π pre for the 16 28 Si + 165 Ho [8], 19 F + 181 Ta [17,83,84], 16 O + 197 Au [8,14], and 16 O + 208 Pb [8,14,85]. Continuous (black) lines indicate the SM predictions including shell correction both in B f and LD and in CELD and K-orientation effects.…”

Section: -5mentioning

confidence: 95%

See 4 more Smart Citations

Detailed statistical model analysis of observables from fusion-fission reactions

2019

Self Cite

View full text Add to dashboard Cite

Background:Despite remarkable success of the statistical model (SM) in describing decay of excited compound nuclei (CN), reproduction of the observables from heavy ion-induced fusion-fission reactions is often quite challenging. Ambiguities in choosing the input parameters, lack of clarity about inclusion of various physical effects in the model, and contradictory requirements of input parameters while describing different observables from similar reactions are among the major difficulties of modeling decay of fissile CN. Purpose: This work attempts to overcome the existing inconsistencies by inclusion of important physical effects in the model and through a systematic analysis of a large set of data over a wide range of CN mass (A CN ). Method: The model includes the shell effect in the level density (LD) parameter, shell correction in the fission barrier (B f ), the effect of the orientation degree of freedom of the CN spin (K or ), collective enhancement of level density (CELD), and dissipation in fission. Input parameters are not tuned to reproduce observables from specific reaction(s) and the reduced dissipation coefficient (β) is treated as the only adjustable parameter. Calculated evaporation residue (ER) cross sections (σ ER ), fission cross sections (σ fiss ), and particle, i.e., neutron, proton, and α particle, multiplicities are compared with data covering A CN = 156-248. Results: The model produces reasonable fits to ER and fission excitation functions for all the reactions considered in this work. Pre-scission neutron multiplicities (ν pre ) are underestimated by the calculation beyond A CN ∼ 200. An increasingly higher value of β, in the range of 2-4 × 10 21 s −1 , is required to reproduce the data with increasing A CN . Proton and α-particle multiplicities, measured in coincidence with both ERs and fission fragments, are in qualitative agreement with model predictions. Conclusions:The present work mitigates the existing inconsistencies in modeling statistical decay of the fissile CN to a large extent. Contradictory requirements of fission enhancement-obtained by scaling down the fission barrier to reproduce σ ER or σ fiss and fission suppression realized by introducing dissipation in the fission channel to reproduce ν pre , for similar reactions-have now become redundant. There are scopes for further refinement of the model, as is evident from the mismatch between measured and calculated particle multiplicities in a few cases.

show abstract

Section: -5supporting

confidence: 69%