Direct evidence of fadeout of collective enhancement in nuclear level density

Banerjee, K.; Roy, Pratap; Pandit, Deepak; Sadhukhan, Jhilam; Bhattacharya, Subhashish; Bhattacharya, C.; Mukherjee, G.; Ghosh, T. K.; Kundu, S.; Sen, A.; Rana, T. K.; Manna, S.; Pandey, R.; Roy, Tufan; Dhal, A.; Asgar, Md. A.; Mukhopadhyay, S.

doi:10.1016/j.physletb.2017.06.033

Cited by 27 publications

(22 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Further validation of our model comes from the close agreement between our estimated 'K' for a heavier system 185 Re * and the experimental data [9]. Our systematic study shows a strong influence of spin induced deformation and shape transitions on NLD [20], and also explains the predictions of decreasing 'K' with spin in the recent works [7,9,21] to be related to the structural changes seen at those spin values, which is the highlight of this work, not seen before in any other work so far to our knowledge.…”

supporting

confidence: 73%

“…This establishes a strong correlation between the deformation and shape phase transitions and the decrease in 'K' with the enhancement of NLD and emission probability in concise with the indication by Refs. [20,21]. Here it may be noted that the enhancement of level density along with the band crossing with sudden decline in 'K' value has been observed at a sharp shape phase transition from oblate to prolate non-collective.…”

mentioning

confidence: 96%

“…The NLD parameter related to the density of the single particle levels near the Fermi surface is influenced by the shell structure and the shape of the nucleus which in turn are profoundly altered * corresponding authors: Mamta Aggarwal, mamta.a4@gmail.com by the excitations [11,12,13,14,15,16,17,18]. Damping of the shell effects on NLD parameter with excitation energy and fadeout of collective enhancement of NLD with shape transition from deformed to spherical, measured recently [21,19,20], point towards the influence of shell structure on NLD that requires a comprehensive investigation within a microscopic framework which exactly is the objective of this letter.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Dependence of spin induced structural transitions on level density and neutron emission spectra

Aggarwal

2019

Nuclear Physics A

View full text Add to dashboard Cite

The impact of spin induced deformation and shape phase transitions on nuclear level density and consequently on neutron emission spectra of the decay of compound nuclear systems 112 Ru to 123 Cs (N = 68 isotones) is investigated in a microscopic framework of Statistical theory of superfluid nuclei. Our calculations are in good accord with experimental data for evaporation residue of 119 Sb and 185 Re and show a strong correlation between spin induced structural transitions and NLD. We find that the inverse level density parameter 'K' increases with increasing spin for all the systems, but it decreases with a deformation or a shape change that results in the enhancement of level dnesity and emission probability. A sharp shape phase transition from oblate to uncommon prolate non-collective in well deformed nuclei leads to band crossing and enhancement of level density which fades away while approaching sphericity at or near shell closure manifesting shell effects.

show abstract

supporting

confidence: 73%

mentioning

confidence: 96%

mentioning

confidence: 99%

See 1 more Smart Citation

Dependence of spin induced structural transitions on level density and neutron emission spectra

Aggarwal

2019

Nuclear Physics A

View full text Add to dashboard Cite

show abstract

“…Such systematics give hints of the form of the nuclear potential corresponding to harmonic oscillator (n = 10) or of Woods-Saxon type (n = 8). In deformed nuclei, such studies have been useful to understand shape transitions of nuclei with excitation energy [34]. From Figures 7 ,8 and 9, we see that the asymptotic values of level densities generally approach a constant value with increase in excitation energy, hinting a similar nuclear potential guiding them throughout the excitation energy.…”

Section: Asymptotic Behaviour Of Nmentioning

confidence: 89%

Ignatyuk damping factor: A semiclassical formula

Dwivedi

Monga

Kaur

et al. 2019

Int. J. Mod. Phys. E

View full text Add to dashboard Cite

Data on nuclear level densities extracted from transmission data or gamma energy spectrum store the basic statistical information about nuclei at various temperatures. Generally this extracted data goes through model fitting using computer codes like CASCADE. However, recently established semiclassical methods involving no adjustable parameters to determine the level density parameter for magic and semi-magic nuclei give a good agreement with the experimental values. One of the popular ways to paramaterize the level density parameter which includes the shell effects and its damping was given by Ignatyuk. This damping factor is usually fitted from the experimental data on nuclear level density and it comes around 0.05 M eV −1 . In this work we calculate the Ignatyuk damping factor for various nuclei using semiclassical methods.

show abstract

“…On the other hand, the earlier experimental studies have produced contradictory results on the collective enhancement and its fadeout [23,24]. Quite recently, our extensive studies on neutron evaporation from several deformed nuclei have established the fact that the fadeout of collectivity is related to the nuclear shape phase transition and occurs at an excitation energy in the region of 14 -21 MeV [25,26]. While, a sharp change in the value of inverse level density parameter (k), within the initial compound nuclear excitation energy interval of 32-37 MeV, is observed for all the deformed nuclei ( 169 Tm, 173 Lu, 185 Re), a weak effect is observed for the near spherical 201 Tl nucleus [26].…”

mentioning

confidence: 99%

Experimental signature of collective enhancement in nuclear level density

Pandit

Bhattacharya²,

Mondal

et al. 2018

Phys. Rev. C

Self Cite

View full text Add to dashboard Cite

We present a probable experimental signature of collective enhancement in the nuclear level density (NLD) by measuring the neutron and the giant dipole resonance (GDR) γ rays emitted from the rare earth 169 Tm compound nucleus populated at 26.1 MeV excitation energy. An enhanced yield is observed in both neutron and γ ray spectra corresponding to the same excitation energy in the daughter nuclei. The enhancement could only be reproduced by including a collective enhancement factor in the Fermi gas model of NLD to explain the neutron and GDR spectra simultaneously. The experimental results show that the relative enhancement factor is of the order of 10 and the fadeout occurs at ∼ 14 MeV excitation energy, much before the commonly accepted transition from deformed to spherical shape. We also explain how the collective enhancement contribution changes the inverse level density parameter (k) from 8 to 9.5 MeV observed recently in several deformed nuclei.

show abstract

Direct evidence of fadeout of collective enhancement in nuclear level density

Cited by 27 publications

References 26 publications

Dependence of spin induced structural transitions on level density and neutron emission spectra

Dependence of spin induced structural transitions on level density and neutron emission spectra

Ignatyuk damping factor: A semiclassical formula

Experimental signature of collective enhancement in nuclear level density

Contact Info

Product

Resources

About