Analytical expressions for the dispersive contributions to the nucleon-nucleus optical potential

Analytical solutions of dispersion relations in the nucleon-nucleus optical model have been found for both volume and surface potentials. For the energy dependence a standard Brown-Rho function has been assumed for both the volume and surface imaginary contributions multiplied in this later case by a decreasing exponential function. The solutions are valid for any even value of the powers appearing in these functional forms.Junta de Andalucía y CICYT FPA2001-0144-C05-03 FPA2001-4960-EUnión Europea KIW-CT-2000-0010

A phenomenological imaginary part of the optical potential for heavy ions

The depth of the imaginary part of the optical potential is derived from the assumption that, at a given energy and for each partial wave L, it is proportional to the compound nucleus density level up to a given excitation energy above the yrast level corresponding to the angular momentum L, and remains a constant for smaller values of L. The prescription is successfully tested for the system 16O + 28Si at nine different projectile energies between 33 and 81 MeV; it fails however at 141.5 MeV, as expected, because other channels, besides elastic scattering and fusion, are important

Perception of innovation in Spain

Purpose: The purpose of this paper is to evaluate the innovation perception, in its different aspects, of the Spanish people. To this end, several ordered logit models have been developed to determine the extent to which socio-demographic characteristics and other aspects of innovation affect the perception of innovation. Design/methodology/approach: This paper analyses the perception of individuals about innovation in Spain and the related factors. It uses 2015 and 2018 data on individuals from Spanish surveys. The data include various measures of innovation perception, age, gender, educational level and other socio-economic variables. Findings: The results indicate that people have a better perception of innovation if they are being trained in innovation or have good information and communication technologies skills. Among the main results, there is a gender gap in the perception of innovation, as well as differences in terms of digital skills. Originality/value: To the best of the authors" knowledge, it is the first time of this kind of analysis in this country. The results are linked to the literature, but should nevertheless be taken into account, which is why some policy recommendations are presented below.This work was supported by the private research project of Company MasMovil and the public research projects of the Spanish Ministry of Economy, Universidad Carlos III de Madrid, and Competitiveness (MINECO), references TEC2017-88048-C2-2-R, RTC-2016-5595-2, RTC-2016-5191-8 and RTC-2016-5059-

Measurements of high-energy neutron-induced fission of natPb and 209Bi

EFNUDAT – Measurements and Models of Nuclear ReactionsThe CERN Neutron Time-Of-Flight (n_TOF) facility is well suited to measure low cross sections as those of neutron-induced fission in subactinides. The cross section ratios of natPb and 209Bi relative to 235U and 238U were measured using PPAC detectors and a fragment coincidence method that allows us to identify the fission events. The present experiment provides first results for neutron-induced fission up to 1 GeV. Good agreement is found with previous experimental data below 200 MeV. The comparison with proton-induced fission indicates that the limiting regime where neutron-induced and proton-induced fission reach equal cross sections is close to 1 Ge

Process design for social empowerment under the inequitable phenomenon of conurbation: new links between Academia and communities

This study aims to improve the welfare of local rurban communities by reducing their vulnerability, thereby empowering them through new strategic partnerships with Academia in order to address the inequitable phenomenon of conurbation, and reappraise the rurban landscape as a cultural capital. The willingness to meet specific demands from members of rurban localities is the driving force for creating an inclusive design process, which consists of three areas: the local community, as well as students and researchers from the Faculty interacting assertively with and in such a context. The design process is focused on providing viable options for communities to relate the physical and social structure systems that make up the habitat to the objective of leveraging their capacity for resilience, as well as strengthening their identity. The creation of new links between Academia and communities at-risk encourages the participation of the three areas that make up the design process. Through communities' experience and cultural capital, a dialogue can be instated between the uncertainty and empowerment of the parties involved. Coexistence between rural and urban landscapes requires a system and structure, which actively promotes the preservation of natural resources and social cohesion. The task of each of the participants encounters its true meaning when practical actions arising from and for the adaptation of the local cultural landscape become a reality. How does one begin if not by opening a dialogue between researchers and student members of vulnerable communities

Application of Photon Strength Functions to (n,g ) measurements with the n_TOF TAC

The neutron capture cross section measurements at the CERN n_TOF facility are performed using a new detection system, the segmented Total Absorption Calorimeter (TAC). All measurements are performed in reference to the well known Au σ(n,γ). The accuracy of the measurements depends on the accuracy of the TAC detection efficiency, which is calculated by means of Monte Carlo simulations. In this MC simulation photon strength functions and level densities play a major role as ingredients used for the generation of primary events, that is the electromagnetic cascades following the (n,γ) process. We have calculated the TAC detection efficiency for the case of Au (n,γ) by adjusting the photon strength functions of Au so that the simulation reproduces the experimental data. Both the MC method and the uncertainty of the results are discussed

Present status and future programs of the n_TOF experiment

CNR*11 – Third International Workshop on Compound Nuclear Reactions and Related TopicsThe neutron time-of-flight facility n_TOF at CERN, Switzerland, operational since 2001, delivers neutrons using the Proton Synchrotron (PS) 20 GeV/c proton beam impinging on a lead spallation target. The facility combines a very high instantaneous neutron flux, an excellent time of flight resolution due to the distance between the experimental area and the production target (185 meters), a low intrinsic background and a wide range of neutron energies, from thermal to GeV neutrons. These characteristics provide a unique possibility to perform neutron-induced capture and fission cross-section measurements for applications in nuclear astrophysics and in nuclear reactor technology. The most relevant measurements performed up to now and foreseen for the future will be presented in this contribution. The overall efficiency of the experimental program and the range of possible measurements achievable with the construction of a second experimental area (EAR-2), vertically located 20 m on top of the n_TOF spallation target, might offer a substantial improvement in measurement sensitivities. A feasibility study of the possible realisation of the installation extension will be also presente

Neutron-induced fission cross section of 234 U measured at the CERN n_TOF facility

The neutron-induced fission cross section of 234U has been measured at the CERN n-TOF facility relative to the standard fission cross section of 235U from 20 keV to 1.4 MeV and of 238U from 1.4 to 200 MeV. A fast ionization chamber (FIC) was used as a fission fragment detector with a detection efficiency of no less than 97%. The high instantaneous flux and the low background characterizing the n-TOF facility resulted in wide-energy-range data (0.02 to 200 MeV), with high energy resolution, high statistics, and systematic uncertainties bellow 3%. Previous investigations around the energy of the fission threshold revealed structures attributed to β-vibrational levels, which have been confirmed by the present measurements. Theoretical calculations have been performed, employing the talys code with model parameters tuned to fairly reproduce the experimental data

The 139 La(n ,γ) cross section: Key for the onset of the s -process

The nuclear resonance parameters and the capture cross section of the neutron magic isotope La139 have been measured relative to Au197 in the energy range of 0.6 eV to 9 keV at the neutron time-of-flight (n_TOF) facility at CERN. We describe the experimental apparatus and the data analysis procedures, which concerned mainly the efficiency correction by means of the pulse height weighting function technique and the determination of different background components. We extracted the resonance parameters and the main nuclear quantities such as the resonance integral RI=10.8±1.0b, the average widths for s and p waves a 1=0=50.7 5.4 meV and l=1=33. 6±6.9 meV, the nuclear level densities l=0=252A 22 eV and l=1<250 eV, and the neutron strength functions S0=(0.82±0.05) Ö10-4 and S1=(0.55±0.04)Ö10-4. These results represent a significant improvement over previous data. The deduced Maxwellian-averaged capture cross sections are important for the interpretation of the most recent spectroscopic observations in low-metallicity stars.EC FIKW-CT-2000-0010

Neutron-induced fission cross section of 245 Cm: New results from data taken at the time-of-flight facility n_TOF

The neutron-induced fission cross section of 245Cm was measured at n-TOF in a wide energy range and with high resolution. The energy dependence, measured in a single measurement from 30 meV to 1 MeV neutron energy, has been determined with 5% accuracy relative to the 235U(n,f) cross section. In order to reduce the uncertainty on the absolute value, the data have been normalized at thermal energy to recent measurements performed at ILL and BR1. In the energy range of overlap, the results are in fair agreement with some previous measurements and confirm, on average, the evaluated cross section in the ENDF/B-VII.0 database, although sizable differences are observed for some important resonances below 20 eV. A similar behavior is observed relative to JENDL/AC-2008, a reactor-oriented database for actinides. The new results contribute to the overall improvement of the databases needed for the design of advanced reactor systems and may lead to refinements of fission models for the actinides.Comisión Europea FIKW-CT-2000-00107 24967