Inclusive deuteron-induced reactions and final neutron states

We present in this paper a formalism for deuteron-induced inclusive reactions. We disentangle direct elastic breakup contributions from other processes (which we generically call non-elastic breakup) implying a capture of the neutron both above and below the neutron emission threshold. The reaction is described as a two step process, namely the breakup of the deuteron followed by the propagation of the neutron-target system driven by an optical potential. The final state interaction between the neutron and the target can eventually form an excited compound nucleus. Within this context, the direct neutron transfer to a sharp bound state is a limiting case of the present formalism.Comment: To appear in the proceedings of the 14th International Conference on Nuclear Reaction Mechanisms, Varenna, Ital

The complete quantification of parametric uncertainties in (d,p) transfer reactions

Previous work quantified the uncertainty associated with the optical potentials between the nucleons and the target. In this study, we extend that work by also including the parameters of the mean field associated with the overlap function of the final bound state, thus obtaining the full parametric uncertainty on transfer observables. We use Bayesian Markov Chain Monte Carlo simulations to obtain parameter posterior distributions. We use elastic-scattering cross sections to constrain the optical potential parameters and use the asymptotic normalization coefficient of the final state to constrain the bound state interaction. We then propagate these posteriors to the transfer angular distributions and obtain confidence intervals for this observable. We study (d,p) reactions on 14C, 16O, and 48Ca at energies in the range E=10-24 MeV. Our results show a strong reduction in uncertainty by using the asymptotic normalization coefficient as a constraint, particularly for those reactions most sensitive to ambiguities in the mean-field. For those reactions, the importance of constraining the bound state interaction is equal to that of constrain the optical potentials. The case of 14C is an outlier because it populates a halo state, and the observable is less sensitive to the nuclear interior. We conclude that when minimal constraints are used on the parameters of the nucleon-target interaction, the 68% confidence interval uncertainties on the differential cross sections are very large (~ 140-185%). However, if elastic-scattering data and the asymptotic normalization coefficient are used in the analysis, with an error of 10% (5%), this uncertainty reduces to ~30% (~15%)

Study of Cluster Structures in Nuclei through the Ratio Method. A Tribute to Mahir Hussein

For one-neutron halo nuclei, the cross section for elastic scattering and breakup at intermediate energy exhibit similar angular dependences. The Recoil Excitation and Breakup (REB) model of reactions elegantly explains this feature. It also leads to the idea of a new reaction observable to study the structure of loosely-bound nuclear systems: the Ratio. This observable consists of the ratio of angular distributions for different reaction channels, viz. elastic scattering and breakup, which cancels most of the dependence on the reaction mechanism; in particular it is insensitive to the choice of optical potentials that simulate the projectile-target interaction. This new observable is very sensitive to the structure of the projectile. In this article, we review the Ratio Method and its extension to low beam energies and proton-halo nuclei.Comment: Submitted to the European Physical Journal A as a contribution to the Special Issue on "Cluster structure and dynamics of nuclei" dedicated to the memory of Mahir S. Hussein (1944-2019). 12 pages, 7 figure

New perspectives on spectroscopic factor quenching from reactions

The evolution of single-particle strengths as the neutron-to-proton asymmetry changes informs us of the importance of short- and long-range correlations in nuclei and has therefore been extensively studied for the last two decades. Surprisingly, the strong asymmetry dependence of these strengths and their extreme values for highly-asymmetric nuclei inferred from knockout reaction measurements on a target nucleus are not consistent with what is extracted from electron-induced, transfer, and quasi-free reaction data, constituting a two-decade old puzzle. This work presents the first consistent analysis of one-nucleon transfer and one-nucleon knockout data, in which theoretical uncertainties associated with the nucleon-nucleus effective interactions considered in the reaction models are quantified using a Bayesian analysis. Our results demonstrate that, taking into account these uncertainties, the spectroscopic strengths of loosely-bound nucleons extracted from both probes agree with each other and, although there are still discrepancies for deeply-bound nucleons, the slope of the asymmetry dependence of the single-particle strengths inferred from transfer and knockout reactions are consistent within $1\sigma$. Both probes are consistent with a small asymmetry dependence of these strengths. The uncertainties obtained in this work represent a lower bound and are already significantly larger than the original estimates.Comment: 14 pages: 7 pages of the main text (including one and a half of reference) and 7 pages of supplemental material. Accepted for publication in Phys. Rev. Let

Uncertainty Quantification in Breakup Reactions

Breakup reactions are one of the favored probes to study loosely bound nuclei, particularly those in the limit of stability forming a halo. In order to interpret such breakup experiments, the continuum discretized coupled channel method is typically used. In this study, the first Bayesian analysis of a breakup reaction model is performed. We use a combination of statistical methods together with a three-body reaction model (the continuum discretized coupled channel method) to quantify the uncertainties on the breakup observables due to the parameters in the effective potential describing the loosely bound projectile of interest. The combination of tools we develop opens the path for a Bayesian analysis of not only breakup processes, but also a wide array of complex processes that require computationally intensive reaction models

Theory of (d,p) and (p,d) reactions including breakup: Comparison of methods

There is an increasing interest in studying transfer reactions to probe the nuclear structure of exotic nuclei. For these loosely bound systems, the role of the continuum needs to be well understood. In this study, we concentrate on (p,d) and (d,p) reactions and compare two formulations for the transfer process that take into account breakup states. Applications to 11Be(p,d)10Be at Elab=38.4 MeV/nucleon and 10Be(d,p)11Be at Elab=12.5 MeV/nucleon are presented, as is a detailed discussion of convergence rates.Ministerio de Ciencia e Innovación FPA2006-13807-c02-01Programa Consolider- Ingenio 2010 CSD2007-0004

Quantifying uncertainties due to optical potentials in one-neutron knockout reactions

One-neutron knockout reactions have been widely used to extract information about the single-particle structure of nuclei from the valley of stability to the driplines. The interpretation of knockout data relies on reaction models, where the uncertainties are typically not accounted for. In this work we quantify uncertainties of optical potentials used in these reaction models and propagate them, for the first time, to knockout observables using a Bayesian analysis. We study two reactions in the present paper, the first of which involves a loosely-bound halo projectile, $^{11}$Be, and the second a tightly-bound projectile, $^{12}$C. We first quantify the parametric uncertainties associated with phenomenological optical potentials. Complementing to this approach, we also quantify the model uncertainties associated with the chiral forces that can be used to construct microscopic optical potentials. For the phenomenological study, we investigate the impact of the imaginary terms of the optical potential on the breakup and stripping components of the knockout cross sections as well as the impact of the angular range. For the $^{11}$Be case, the theoretical uncertainty from the phenomenological method is on the order of the experiment uncertainty on the knockout observables; however, for the $^{12}$C case, the theoretical uncertainty is significantly larger. The widths of the confidence intervals for the knockout observables obtained for the microscopic study and the phenomenological approach are of similar order of magnitude. Based on this work we conclude that structure information inferred from the ratio of the knockout cross sections, will carry a theoretical uncertainty of at least $20\%$ for halo nuclei and at least $40\%$ for tightly-bound nuclei.Comment: 12 pages (including 2 of supplemental material and 1 of reference), 5 figures, 2 table

Biocompounds recovery from Spirulina by conventional and ohmic heating methodologies: chemical and biological properties

Extracting the totality of bio-compounds with industrial interest from Cyanobacterium is often prevented by the intrinsic rigidity of its cell wall. In this sense, the present study focuses on evaluating the influence thermal batch extraction (conventional extraction technologies) and ohmic heating (OH) assisted extraction (considered a greener alternative technology) in blue green microalgae Arthrospira platensis (Spirulina) cell disruption for bioactive fractions recovery. The proximal composition of Spirulina was initially determined. The maximum protein content (i.e., CPhycocyanin), total carbohydrates (TC) and total phenolic compounds (TPC) extracted in water at different times (30-120 min) and temperatures (30-51 ºC) was quantified after the conventional and OH- assisted extraction. The freeze-thawing process was used as control. The antioxidant activity (i.e., FRAP and DPPH assays) of the obtained extracts was assessed. Results showed that with the freeze-thawing process, traditionally used for the recovery of bio- compounds from Spirulina, the concentration of C-phycocyanin was approx. 42 mg/g of Spirulina, 26 mgGlcE/g Spirulina of TC and 9 mgGAE/g Spirulina of TPC. Using OH-assisted extraction, the maximum of C-Phycocyanin content obtained was 45 mg/g of Spirulina (obtained at 37 ºC, 30 min), the maximum carbohydrates content was 40 mgGlcE/g Spirulina and the maximum TPC was 10 mgGAE/g Spirulina. On the other hand, using conventional thermal treatment it can be observed that, under the same conditions, the bioactive compounds recovery decreased to 35 mg/g, 20 mgGlcE/g Spirulina for C-phycocyanin concentration and TC (p<0.05), respectively. The concentration in phenolic compounds is not so affected, but even so the ohmic heating potentiates the extraction of these secondary metabolites. The antioxidant activity of the extracts there was not different between conventional treatments andOH. Thus, the results indicated that OH is a good alternative to conventional methods aiming at the extraction of intracellular components with a decrease in processing time and energy costs associated with the extraction process, which together with an easy upscale make OH an interesting methodology for use in the industrial production of microalgae colorants and bioactive supplements.info:eu-repo/semantics/publishedVersio