Measurement of the 77Se(n,¿) cross section up to 200 keV at the n_TOF facility at CERN

The 77Se(n,¿) reaction is of importance for 77Se abundance during the slow neutron capture process in massive stars. We have performed a new measurement of the 77Se radiative neutron capture cross section at the Neutron Time-of-Flight facility at CERN. Resonance capture kernels were derived up to 51 keV and cross sections up to 200 keV. Maxwellian-averaged cross sections were calculated for stellar temperatures between kT=5keV and kT=100keV, with uncertainties between 4.2% and 5.7%. Our results lead to substantial decreases of 14% and 19% in 77Se abundances produced through the slow neutron capture process in selected stellar models of 15M¿ and 2M¿, respectively, compared to using previous recommendation of the cross section.This work was supported by the UK Science and Facilities Council (ST/M006085/1), the MSMT of the Czech Republic, the Charles University UNCE/SCI/013 project, the European Research Council ERC-2015-StG No. 677497, and by the funding agencies of the participating institutes. In line with the principles that apply to scientific publishing and the CERN policy in matters of scientific publications, the n_TOF Col- laboration recognizes the work of Y. Kopatch and V. Furman (JINR, Russia), who have contributed to the experiment used to obtain the results described in this paper.Article signat per 131 autors/es: N. V. Sosnin , C. Lederer-Woods, M. Krtiˇcka, R. Garg, M. Dietz, M. Bacak, M. Barbagallo, U. Battino, S. Cristallo, L. A. Damone, M. Diakaki, S. Heinitz, D. Macina, M. Mastromarco, F. Mingrone, A. St. J. Murphy, G. Tagliente, S. Valenta, D. Vescovi, O. Aberle, V. Alcayne, S. Amaducci, J. Andrzejewski, L. Audouin, V. Bécares, V. Babiano-Suarez, F. Beˇcváˇr, G. Bellia, E. Berthoumieux, J. Billowes, D. Bosnar, A. Brown, M. Busso, M. Caamaño, L. Caballero, F. Calviño, M. Calviani, D. Cano-Ott, A. Casanovas, F. Cerutti, Y. H. Chen, E. Chiaveri, N. Colonna, G. Cortés, M. A. Cortés-Giraldo, L. Cosentino, C. Domingo-Pardo, R. Dressler, E. Dupont, I. Durán, Z. Eleme, B. Fernández-Domínguez, A. Ferrari, P. Finocchiaro, K. Göbel, A. Gawlik-Rami˛ega, S. Gilardoni, T. Glodariu, I. F. Gonçalves, E. González-Romero, C. Guerrero, F. Gunsing, H. Harada, J. Heyse, D. G. Jenkins, E. Jericha, F. Käppeler, Y. Kadi, A. Kimura, N. Kivel, M. Kokkoris, D. Kurtulgil, I. Ladarescu, H. Leeb, J. Lerendegui-Marco, S. Lo Meo, S. J. Lonsdale, A. Manna, T. Martínez, A. Masi, C. Massimi, P. Mastinu, F. Matteucci, E. A. Maugeri, A. Mazzone, E. Mendoza, A. Mengoni, V. Michalopoulou, P. M. Milazzo, A. Musumarra, A. Negret, R. Nolte, F. Ogállar, A. Oprea, N. Patronis, A. Pavlik, J. Perkowski, L. Piersanti, I. Porras, J. Praena, J. M. Quesada, D. Radeck, D. Ramos-Doval, T. Rauscher, R. Reifarth, D. Rochman, C. Rubbia, M. Sabaté-Gilarte, A. Saxena, P. Schillebeeckx, D. Schumann, A. G. Smith, A. Stamatopoulos, J. L. Tain, T. Talip, A. Tarifeño-Saldivia, L. Tassan-Got, P. Torres-Sánchez, A. Tsinganis, J. Ulrich, S. Urlass, G. Vannini, V. Variale, P. Vaz, A. Ventura, V. Vlachoudis, R. Vlastou, A. Wallner, P. J. Woods,T. Wright, and P. Žugec.Postprint (published version

First Results of the 140^{140}Ce(n,γ)141^{141}Ce Cross-Section Measurement at n_TOF

An accurate measurement of the $^{140}$Ce(n,γ) energy-dependent cross-section was performed at the n_TOF facility at CERN. This cross-section is of great importance because it represents a bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in stars. The measurement was motivated by the significant difference between the cerium abundance measured in globular clusters and the value predicted by theoretical stellar models. This discrepancy can be ascribed to an overestimation of the $^{140}$Ce capture cross-section due to a lack of accurate nuclear data. For this measurement, we used a sample of cerium oxide enriched in $^{140}$Ce to 99.4%. The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which allowed us to overcome the difficulties present in the previous measurements, thanks to their very low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their average parameters are fundamental to improve the evaluation of the $^{140}$Ce Maxwellian-averaged cross-section

First Results of the 140^{140}Ce(n,γ)141^{141}Ce Cross-Section Measurement at n_TOF

An accurate measurement of the $^{140}$Ce(n,γ) energy-dependent cross-section was performed at the n_TOF facility at CERN. This cross-section is of great importance because it represents a bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in stars. The measurement was motivated by the significant difference between the cerium abundance measured in globular clusters and the value predicted by theoretical stellar models. This discrepancy can be ascribed to an overestimation of the $^{140}$Ce capture cross-section due to a lack of accurate nuclear data. For this measurement, we used a sample of cerium oxide enriched in $^{140}$Ce to 99.4%. The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which allowed us to overcome the difficulties present in the previous measurements, thanks to their very low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their average parameters are fundamental to improve the evaluation of the $^{140}$Ce Maxwellian-averaged cross-section

Atomic Number and Gamma-ray Measurements from Neutron-induced Fission at the ILL and n_ToF

The STEFF spectrometer was used at the Neutron Time-of-Flight facility (n_ToF) at CERN in 2016 to perform a 30-day long experimental campaign of measurements of fission fragments and gamma rays produced in $^{235}$U fission for a wide range of incident neutron energies. A pipeline for reading, correlating and database deposition of the experimental data from this experimental campaign as well as for future STEFF campaigns at n_ToF has been constructed. The pipeline resulted in 70-fold data size reduction to an experimental database that can be fully processed in ~7 hours. The collected gamma-ray data acquired using NaI and LaBr3 detectors have been analyzed in the <1 eV neutron energy range and compared to prior STEFF 235U fission gamma-ray measurements. A method for correcting NaI signal amplitudes for n_ToF-specific effects, such as rates and pulse types, based on fission gamma-ray spectrum shape has been developed. The correcting factors were the greatest for the dedicated proton pulses at neutron energies of ~0.06 eV, increasing signal amplitude by approximately a factor of 2. Corrections to LaBr$_{3}$ signals have also been considered and performed based on count rates, with the the largest correcting factors reducing signal amplitude by ~15%. The corrected and calibrated energy spectra and calculated fold distributions have been prepared for extraction of gamma-ray multiplicity, average energy and total energy in thermal and epithermal fission of $^{235}$U. An experiment was conducted at the Lohengrin mass spectrometer at Institut Laue-Langevin, France, using a FiFI spectrometer for measurement of masses and atomic numbers of selected $^{235}$U fission fragments. The details of the experiment and the data analysis are presented, and a method for calibrating Bragg detectors for atomic number extraction is proposed. The method is based on amplitudes, derivatives and risetimes of signals produced by fission fragments in isobutane fill gas. The extracted signal properties were used in conjunction with known fragment masses and energies to produce functional forms based on powers of fragment velocities and average atomic numbers. Furthermore, a comparison with simulations produced in SRIM-2013 was performed, assessing the accuracy of the simulations

Atomic Number and Gamma-ray Measurements from Neutron-induced Fission at the ILL and n_ToF

The STEFF spectrometer was used at the Neutron Time-of-Flight facility (n_ToF) at CERN in 2016 to perform a 30-day long experimental campaign of measurements of fission fragments and gamma rays produced in $^{235}$U fission for a wide range of incident neutron energies. A pipeline for reading, correlating and database deposition of the experimental data from this experimental campaign as well as for future STEFF campaigns at n_ToF has been constructed. The pipeline resulted in 70-fold data size reduction to an experimental database that can be fully processed in ~7 hours. The collected gamma-ray data acquired using NaI and LaBr3 detectors have been analyzed in the <1 eV neutron energy range and compared to prior STEFF 235U fission gamma-ray measurements. A method for correcting NaI signal amplitudes for n_ToF-specific effects, such as rates and pulse types, based on fission gamma-ray spectrum shape has been developed. The correcting factors were the greatest for the dedicated proton pulses at neutron energies of ~0.06 eV, increasing signal amplitude by approximately a factor of 2. Corrections to LaBr$_{3}$ signals have also been considered and performed based on count rates, with the the largest correcting factors reducing signal amplitude by ~15%. The corrected and calibrated energy spectra and calculated fold distributions have been prepared for extraction of gamma-ray multiplicity, average energy and total energy in thermal and epithermal fission of $^{235}$U. An experiment was conducted at the Lohengrin mass spectrometer at Institut Laue-Langevin, France, using a FiFI spectrometer for measurement of masses and atomic numbers of selected $^{235}$U fission fragments. The details of the experiment and the data analysis are presented, and a method for calibrating Bragg detectors for atomic number extraction is proposed. The method is based on amplitudes, derivatives and risetimes of signals produced by fission fragments in isobutane fill gas. The extracted signal properties were used in conjunction with known fragment masses and energies to produce functional forms based on powers of fragment velocities and average atomic numbers. Furthermore, a comparison with simulations produced in SRIM-2013 was performed, assessing the accuracy of the simulations

HOW TO TRANSFER COMPETENCIES INTO THE LEARNING CONTENT

The article discusses the problem of content structure of competence2oriented learning. It is argued that the key issue in this problem is the way to transfer competencies of a graduate into learning content of educational program. Integrative and beyond2disciplinary nature of the competencies requires changes to traditional disciplinary model. A concept is proposed, according to which firstly the structure of the learning outcomes is designed and then it turns into the content of the structural units of the learning process

СРЕДСТВА ПСЕВДОКОДОВОГО МОДЕЛИРОВАНИЯ В ПРОЦЕССЕ ПРОЕКТИРОВАНИЯ ПРОГРАММ ЧИСЛОВОГО УПРАВЛЕНИЯ

The purpose of this operation is enhancement of deve-lopment processes of programs of a numerical control for machines with CNC (turning and milling processing) due to improvement of quality of their design. At the moment a large number of operations in the field of automation of development processes unitary enterprise is oriented, on application of CAD/CAM-systems, however, within these operations the considered decisions, often, have or too narrow focus, or automation has local character. Such decisions, as a rule, fully don’t respond the tasks facing production. The decision considered in this article is based on implementation of a complex of means of pseudo-code simulation in development process of the controlling programs which cornerstone the expanded pseudo-code mo-deling language promoting lowering of labor input of design, modifiability, portability and an adaptability unitary enterprise is. Thus the complex consists from: pseudo-code language; the integrated environment of pseudo-code programming with two versions of the interpreter and the compiler (step by step and group); visualization tools on the basis of the editor of charts, sets of techniques of pseudo-code simulation.Целью данной работы является совершенствование процессов разработки программ числового управления для станков с ЧПУ (токарной и фрезерной обработки) за счет повышения качества их проектирования. На текущий момент большое количество работ в области автоматизации процессов разработки УП ориентировано, на применение CAD/CAM-систем, однако, в рамках этих работ рассматриваемые решения, зачастую, имеют либо слишком узкую направленность, либо автоматизация носит локальный характер. Такие решения, как правило, в полной мере не отвечают стоящим перед производством задачам. Решение рассматриваемое в данной статье основывается на внедрении комплекса средств псевдокодового моделирования в процесс разработки управляющих программ, в основе которых лежит расширяемый псевдокодовый язык моделирования, способствующий снижению трудоемкости проектирования, модифицируемости, переносимости и адаптируемости УП. При этом сам комплекс состоит из: псевдокодового языка; интегрированной среды псевдокодового программирования с двумя версиями интерпретатора и компилятора (пошаговый и групповой); средства визуализации на основе редактора диаграмм, совокупности методик псевдокодового моделирования