Evidence for the reduction of nuclear level density away from the 
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-stability line

Roy, Pratap; Banerjee, K.; Rana, T. K.; Kundu, S.; Manna, S.; Sen, A.; Mondal, Debashis; Sadhukhan, Jhilam; Kannan, M. T. Senthil; Ghosh, T. K.; Mukhopadhyay, S.; Pandit, Deepak; Mukherjee, G.; Pal, Santanu; Paul, D.; Atreya, K.; Bhattacharya, C.

doi:10.1103/physrevc.102.061601

Cited by 9 publications

(7 citation statements)

References 51 publications

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“…Recently, there are some measurements on the level densities for the nuclei with |Z −Z 0 | > 1. The measured NLDs for 70 Ni (Z −Z 0 = 3) [9] and 115 Te (Z −Z 0 = 2) [13] manifest that the strong reduction in NLDs as predicted by AlQuraishi et al [17] are overestimated. This suggests that the extrapolation beyond |Z − Z 0 | = 1 needs to be re-examined.…”

Section: Introductionmentioning

confidence: 68%

Nuclear level densities away from line of $β$-stability

Ghosh,

Maheshwari,

Saxena

et al. 2021

Preprint

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The variation of total nuclear level densities (NLDs) and level density parameters with proton number (Z) are studied around the β-stable isotope, Z 0 , for a given mass number. We perform our analysis for a mass range A = 40 to 180 using the NLDs from popularly used databases obtained with the singleparticle energies from two different microsopic mass-models. These NLDs which include microscopic structural effects such as collective enhancement, pairing and shell corrections, do not exhibit inverted parabolic trend with a strong peak at Z 0 as predicted earlier. We also compute the NLDs using the singleparticle energies from macroscopic-microscopic mass-model. Once the collective and pairing effects are ignored, the inverted parabolic trends of NLDs and the corresponding level density parameters become somewhat visible. Nevertheless, the factor that governs the (Z − Z 0 ) dependence of the level density parameter, leading to the inverted parabolic trend, is found to be smaller by an order of magnitude. We further find that the (Z − Z 0 ) dependence of NLDs is quite sensitive to the shell effects.

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Section: Introductionmentioning

confidence: 68%

Nuclear level densities away from line of $β$-stability

Ghosh,

Maheshwari,

Saxena

et al. 2021

Preprint

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“…Perhaps some of the need for scaling is due to inconsistent or lacking discrete level data that feeds into the level density models. The residual products of interest generally exist off the line of stability and resonance parameters are unknown [115][116][117]. In 70 As and 72 As, only 68 and 65 experimental discrete levels, respectively, as stored in the RIPL-3 database, inform the level density calculations [34].…”

Section: Level Density Adjustmentsmentioning

confidence: 99%

“…This lack of structure data exists for 66,67 Ge and 66,68 Ga within their respective isotope chains as well. Ultimately, it is conceivable that incomplete structure data leads to numerous compensating level density effects in this mass region, which may themselves be a key contributor to the ad- justed scalings as opposed to any inherent issues with the models [115][116][117].…”

Section: Level Density Adjustmentsmentioning

confidence: 99%

“…It is also possible that a disregard of isospin effects in the current TALYS calculations, missing collective enhancement effects for nuclei far from stability, or deterioration of the microscopic level density models altogether at the high excitation energies relevant to this work, have prompted the need for the corrective scalings [117,118]. A future experiment examining α+ 72 Ge, which populates the same 76 Se compound system as p+ 75 As but with different isospin, could provide some additional information.…”

Section: Level Density Adjustmentsmentioning

confidence: 99%

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Measurement and modeling of proton-induced reactions on arsenic from 35 to 200 MeV

et al. 2021

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72 As is a promising positron emitter for diagnostic imaging that can be employed locally using a 72 Se generator. However, current reaction pathways to 72 Se have insufficient nuclear data for efficient production using regional 100-200 MeV high-intensity proton accelerators. In order to address this deficiency, stacked-target irradiations were performed at LBNL, LANL, and BNL to measure the production of the 72 Se/ 72 As PET generator system via 75 As(p,x) between 35 and 200 MeV. This work provides the most well-characterized excitation function for 75 As(p,4n) 72 Se starting from threshold. Additional focus was given to report the first measurements of 75 As(p,x) 68 Ge and bolster an already robust production capability for the highly valuable 68 Ge/ 68 Ga PET generator. Thick target yield comparisons with prior established formation routes to both generators are made. In total, high-energy proton-induced cross sections are reported for 55 measured residual products from 75 As, nat Cu, and nat Ti targets, where the latter two materials were present as monitor foils. These results were compared with literature data as well as the default theoretical calculations of the nuclear model codes TALYS, CoH, EMPIRE, and ALICE. Reaction modeling at these energies is typically unsatisfactory due to few prior published data and many interacting physics models. Therefore, a detailed assessment of the TALYS code was performed with simultaneous parameter adjustments applied according to a standardized procedure. Particular attention was paid to the formulation of the two-component exciton model in the transition between the compound and preequilibrium regions, with a linked investigation of level density models for nuclei off of stability and their impact on modeling predictive power. This paper merges experimental work and evaluation techniques for high-energy charged-particle isotope production in an extension to an earlier study of this kind.

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“…Many theoretical and experimental efforts are made to estimate NLDs of nuclei away from line of stability [9][10][11][12][13]. Usually, one extrapolates the level densities beyond the stability line on the basis of known values.…”

Section: Introductionmentioning

confidence: 99%

Nuclear level densities away from line of β-stability

Ghosh¹,

Maheshwari²,

Arora³

et al. 2022

J. Phys. G: Nucl. Part. Phys.

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The variation of total nuclear level densities (NLDs) and level density parameters with proton number Z are studied around the β-stable isotope, Z0, for a given mass number. We perform our analysis for a mass range A=40 to 180 using the NLDs from popularly used databases obtained with the single-particle energies from two different microsopic mass-models. These NLDs which include microscopic structural effects such as collective enhancement, pairing and shell corrections, do not exhibit inverted parabolic trend with a strong peak at Z0 as predicted earlier. We also compute the NLDs using the single-particle energies from macroscopic-microscopic mass-model. Once the collective and pairing effects are ignored, the inverted parabolic trends of NLDs and the corresponding level density parameters become somewhat visible. Nevertheless, the factor that governs the (Z-Z0) dependence of the level density parameter, leading to the inverted parabolic trend, is found to be smaller by an order of magnitude. We further find that the (Z-Z0) dependence of NLDs is quite sensitive to the shell effects.

show abstract

Evidence for the reduction of nuclear level density away from the β -stability line

Cited by 9 publications

References 51 publications

Nuclear level densities away from line of $β$-stability

Nuclear level densities away from line of $β$-stability

Measurement and modeling of proton-induced reactions on arsenic from 35 to 200 MeV

Nuclear level densities away from line of β-stability

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