Pub Date : 2023-04-14DOI: 10.1051/epjconf/202328406004
N. Mont-Geli, A. Tarifeño-Saldivia, L. Fraile, S. Viñals, A. Perea, M. Pallas, G. Cortes, E. Nácher, J. Tain, V. Alcayne, A. Algora, J. Balibrea-Correa, J. Benito, M. Borge, J. Briz, F. Calviño, D. Cano-Ott, A. de Blas, C. Domingo-Pardo, B. Fernández, R. Garcia, G. García, J. Gómez-Camacho, E. González-Romero, C. Guerrero, J. Lerendegui-Marco, M. Llanos, T. Martínez, E. Mendoza, J. Murias, S. Orrigo, A. Pérez de Rada, V. Pesudo, J. Plaza, J. Quesada, A. Sanchez, V. Sánchez-Tembleque, R. Santorelli, O. Tengblad, J. Udías, D. Villamarín
miniBELEN is a modular and transportable neutron moderated counter with a nearly flat neutron detection efficiency up to 10 MeV. Modularity implies that the moderator can be reassembled in different ways in order to obtain different types of response. The detector has been developed in the context of the Measurement of Alpha Neutron Yields (MANY) collaboration, which is a scientific effort aiming to carry out measurements of (𝛼, 𝑛) production yields, reaction cross-sections and neutron energy spectra. In this work we present and discuss several configurations of the miniBELEN detector. The experimental validation of the efficiency calculations using 252Cf sources and the measurement of the 27Al(𝛼, 𝑛) 30P reaction is also presented.
{"title":"miniBELEN: A modular neutron counter for (𝜶, 𝒏) reactions","authors":"N. Mont-Geli, A. Tarifeño-Saldivia, L. Fraile, S. Viñals, A. Perea, M. Pallas, G. Cortes, E. Nácher, J. Tain, V. Alcayne, A. Algora, J. Balibrea-Correa, J. Benito, M. Borge, J. Briz, F. Calviño, D. Cano-Ott, A. de Blas, C. Domingo-Pardo, B. Fernández, R. Garcia, G. García, J. Gómez-Camacho, E. González-Romero, C. Guerrero, J. Lerendegui-Marco, M. Llanos, T. Martínez, E. Mendoza, J. Murias, S. Orrigo, A. Pérez de Rada, V. Pesudo, J. Plaza, J. Quesada, A. Sanchez, V. Sánchez-Tembleque, R. Santorelli, O. Tengblad, J. Udías, D. Villamarín","doi":"10.1051/epjconf/202328406004","DOIUrl":"https://doi.org/10.1051/epjconf/202328406004","url":null,"abstract":"miniBELEN is a modular and transportable neutron moderated counter with a nearly flat neutron detection efficiency up to 10 MeV. Modularity implies that the moderator can be reassembled in different ways in order to obtain different types of response. The detector has been developed in the context of the Measurement of Alpha Neutron Yields (MANY) collaboration, which is a scientific effort aiming to carry out measurements of (𝛼, 𝑛) production yields, reaction cross-sections and neutron energy spectra. In this work we present and discuss several configurations of the miniBELEN detector. The experimental validation of the efficiency calculations using 252Cf sources and the measurement of the 27Al(𝛼, 𝑛) 30P reaction is also presented.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"71 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86403704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-14DOI: 10.1051/epjconf/202226605011
M. Walther, T. Siefke, Kristin Gerold, U. Zeitner
Vanadium dioxide as a phase change material is usually known for its consideration in smart window applications. However, the attention shifts to using it in actively switched optical elements. The main challenges are the deposition of vanadium dioxide with the correct stoichiometry and phase and the patterning of the material. We propose a design with a corresponding manufacturing process for an actively switchable reflector at 1550 nm wavelength with a contrast near 105 by using the thermochromic effect of vanadium dioxide. The reflectance of the proposed optical element can be controlled between an ultra-low and a high reflecting state. We elaborate on the proposed optical design, the manufacturing process including deposition, annealing and patterning processes, and discuss already achieved results.
{"title":"Switchable optics based on guided mode resonance in lithographically patterned vanadium dioxide","authors":"M. Walther, T. Siefke, Kristin Gerold, U. Zeitner","doi":"10.1051/epjconf/202226605011","DOIUrl":"https://doi.org/10.1051/epjconf/202226605011","url":null,"abstract":"Vanadium dioxide as a phase change material is usually known for its consideration in smart window applications. However, the attention shifts to using it in actively switched optical elements. The main challenges are the deposition of vanadium dioxide with the correct stoichiometry and phase and the patterning of the material. We propose a design with a corresponding manufacturing process for an actively switchable reflector at 1550 nm wavelength with a contrast near 105 by using the thermochromic effect of vanadium dioxide. The reflectance of the proposed optical element can be controlled between an ultra-low and a high reflecting state. We elaborate on the proposed optical design, the manufacturing process including deposition, annealing and patterning processes, and discuss already achieved results.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81336405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-28DOI: 10.1051/epjconf/202328305005
J. Blažek, J. Ebr, J. Vícha, T. Pierog, P. Trávníček
We have implemented ad-hoc modifications to the CORSIKA Monte-Carlo generator which allow us to simultaneously adjust the multiplicity, elasticity and cross-section of hadronic interactions with respect to the predictions of the Sibyll 2.3d interaction model, in order to assess whether a reasonable combination of changes (that is not excluded by current experimental data) could alleviate the observed tension between the model predictions and observed features of extensive air showers induced by ultra-high energy cosmic rays (UHECR). Previously, we have studied the effects of such changes on proton-initiated showers. Because a multitude of experimental data suggest that the primary composition of the UHECR is mixed, we have expanded the modification procedure to include nuclear projectiles in a consistent way based on the superposition model, in a similar manner as was used in the previous studies carried out using one-dimensional simulation methods. As we are using a fully three-dimensional approach, we can quantify the effects of the changes on both longitudinal and lateral features of the showers. With the inclusion of nuclear projectiles, we can study the impact of the changes on observable quantities for realistic primary beams as well as on the determination of the primary composition from data under the assumption of the modified hadronic interactions.
{"title":"A Study of Modified Characteristics of Hadronic Interactions","authors":"J. Blažek, J. Ebr, J. Vícha, T. Pierog, P. Trávníček","doi":"10.1051/epjconf/202328305005","DOIUrl":"https://doi.org/10.1051/epjconf/202328305005","url":null,"abstract":"We have implemented ad-hoc modifications to the CORSIKA Monte-Carlo generator which allow us to simultaneously adjust the multiplicity, elasticity and cross-section of hadronic interactions with respect to the predictions of the Sibyll 2.3d interaction model, in order to assess whether a reasonable combination of changes (that is not excluded by current experimental data) could alleviate the observed tension between the model predictions and observed features of extensive air showers induced by ultra-high energy cosmic rays (UHECR). Previously, we have studied the effects of such changes on proton-initiated showers. Because a multitude of experimental data suggest that the primary composition of the UHECR is mixed, we have expanded the modification procedure to include nuclear projectiles in a consistent way based on the superposition model, in a similar manner as was used in the previous studies carried out using one-dimensional simulation methods. As we are using a fully three-dimensional approach, we can quantify the effects of the changes on both longitudinal and lateral features of the showers. With the inclusion of nuclear projectiles, we can study the impact of the changes on observable quantities for realistic primary beams as well as on the determination of the primary composition from data under the assumption of the modified hadronic interactions.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82070549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-28DOI: 10.1051/epjconf/202328303003
E. Mayotte, T. Fitoussi
We test for an anisotropy in the mass of arriving cosmic-ray primaries associated with the galactic plane. The sensitivity to primary mass is obtained through the depth of shower maximum, X max, extracted from hybrid events measured over a 14-year period at the Pierre Auger Observatory. The sky is split into distinct on-and off-plane regions using the galactic latitude of each arriving cosmic ray to form two distributions of X max, which are compared using an Anderson-Darling 2-samples test. A scan over roughly half of the data is used to select a lower threshold energy of 1018.7 eV and a galactic latitude splitting at |b| = 30°, which are set as a prescription for the remaining data. With these thresholds, the distribution of X max from the on-plane region is found to have a 9.1±1.6−2.2+2.1g/cm2 shallower mean and a 5.9±2.1−2.5+3.5g/cm2 narrower width than that of the off-plane region and is observed in all telescope sites independently. These di↵erences indicate that the mean mass of primary particles arriving from the on-plane region is greater than that of those from the off-plane region. Monte Carlo studies yield a 5.9 ×10−6 random chance probability for the result in the independent data, lowering to a 6.0 × 10−7 post-penalization random chance probability when the scanned data is included. Accounting for systematic uncertainties leads to an indication for anisotropy in mass composition above 1018.7 eV with a 3.3 σ-significance. Furthermore, the result has been newly tested using additional FD data recovered from the selection process. This test independently disfavors the on-and off-plane regions being uniform in composition at the 2.2 σ-level, which is in good agreement with the expected sensitivity of the dataset used for this test.
{"title":"Update on the indication of a mass-dependent anisotropy above 1018.7 eV in the hybrid data of the Pierre Auger Observatory","authors":"E. Mayotte, T. Fitoussi","doi":"10.1051/epjconf/202328303003","DOIUrl":"https://doi.org/10.1051/epjconf/202328303003","url":null,"abstract":"We test for an anisotropy in the mass of arriving cosmic-ray primaries associated with the galactic plane. The sensitivity to primary mass is obtained through the depth of shower maximum, X max, extracted from hybrid events measured over a 14-year period at the Pierre Auger Observatory. The sky is split into distinct on-and off-plane regions using the galactic latitude of each arriving cosmic ray to form two distributions of X max, which are compared using an Anderson-Darling 2-samples test. A scan over roughly half of the data is used to select a lower threshold energy of 1018.7 eV and a galactic latitude splitting at |b| = 30°, which are set as a prescription for the remaining data. With these thresholds, the distribution of X max from the on-plane region is found to have a 9.1±1.6−2.2+2.1g/cm2 shallower mean and a 5.9±2.1−2.5+3.5g/cm2 narrower width than that of the off-plane region and is observed in all telescope sites independently. These di↵erences indicate that the mean mass of primary particles arriving from the on-plane region is greater than that of those from the off-plane region. Monte Carlo studies yield a 5.9 ×10−6 random chance probability for the result in the independent data, lowering to a 6.0 × 10−7 post-penalization random chance probability when the scanned data is included. Accounting for systematic uncertainties leads to an indication for anisotropy in mass composition above 1018.7 eV with a 3.3 σ-significance. Furthermore, the result has been newly tested using additional FD data recovered from the selection process. This test independently disfavors the on-and off-plane regions being uniform in composition at the 2.2 σ-level, which is in good agreement with the expected sensitivity of the dataset used for this test.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79495644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-26DOI: 10.1051/epjconf/202328302012
J. V'icha
We present a method for testing the predictions of hadronic interaction models and improving their consistency with observed two-dimensional distributions of the depth of shower maximum, X max, and signal at the ground level as a function of zenith angle. The method relies on the assumption that the mass composition is the same at all zenith angles, while the atmospheric shower development and attenuation depend on composition in a correlated way. In the present work, for each of the three leading LHC-tuned hadronic interaction models, we allow a global shift ∆ X max of the predicted shower maximum, which is the same for every mass and energy, and a rescaling R Had of the hadronic component at the ground level which is constant with the zenith angle. We apply the analysis to 2297 events reconstructed with both the fluorescence and surface detectors of the Pierre Auger Observatory with energies 1018.5−19.0 eV and zenith angles below 60°. Given the modeling assumptions made in this analysis, the best fit reaches its optimum value when shifting the X max predictions of hadronic interaction models to deeper values and increasing the hadronic signal. This change in the predicted X max scale alleviates the previously identified model deficit in the hadronic signal (commonly called the muon puzzle) but does not fully remove it. Because of the size of the adjustments ∆ X max and R Had and the large number of events in the sample, the statistical significance of need for these adjustments is large, greater than 5σstat, even for the combination of the systematic experimental shifts within 1σsys that are the most favorable for the models.
{"title":"Testing Model Predictions of Depth of Air-Shower Maximum and Signals in Surface Detectors using Hybrid Data of the Pierre Auger Observatory","authors":"J. V'icha","doi":"10.1051/epjconf/202328302012","DOIUrl":"https://doi.org/10.1051/epjconf/202328302012","url":null,"abstract":"We present a method for testing the predictions of hadronic interaction models and improving their consistency with observed two-dimensional distributions of the depth of shower maximum, X max, and signal at the ground level as a function of zenith angle. The method relies on the assumption that the mass composition is the same at all zenith angles, while the atmospheric shower development and attenuation depend on composition in a correlated way. In the present work, for each of the three leading LHC-tuned hadronic interaction models, we allow a global shift ∆ X max of the predicted shower maximum, which is the same for every mass and energy, and a rescaling R Had of the hadronic component at the ground level which is constant with the zenith angle. We apply the analysis to 2297 events reconstructed with both the fluorescence and surface detectors of the Pierre Auger Observatory with energies 1018.5−19.0 eV and zenith angles below 60°. Given the modeling assumptions made in this analysis, the best fit reaches its optimum value when shifting the X max predictions of hadronic interaction models to deeper values and increasing the hadronic signal. This change in the predicted X max scale alleviates the previously identified model deficit in the hadronic signal (commonly called the muon puzzle) but does not fully remove it. Because of the size of the adjustments ∆ X max and R Had and the large number of events in the sample, the statistical significance of need for these adjustments is large, greater than 5σstat, even for the combination of the systematic experimental shifts within 1σsys that are the most favorable for the models.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83805169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-24DOI: 10.1051/epjconf/202226613007
J. M. Crespo, V. Moreno
The use of convolutional neuronal networks (CNN) for the treatment of interferometric fringes has been introduced in recent years. In this paper, we optimize and build a CNN model, based U-NET architecture, to maximize its performance processing electronic speckle interferometry fringes (ESPI).
{"title":"Convolutional neural network optimisation to enhance ESPI fringe visibility","authors":"J. M. Crespo, V. Moreno","doi":"10.1051/epjconf/202226613007","DOIUrl":"https://doi.org/10.1051/epjconf/202226613007","url":null,"abstract":"The use of convolutional neuronal networks (CNN) for the treatment of interferometric fringes has been introduced in recent years. In this paper, we optimize and build a CNN model, based U-NET architecture, to maximize its performance processing electronic speckle interferometry fringes (ESPI).","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89889309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-22DOI: 10.1051/epjconf/202327912002
S. Orrigo, B. Rubio, W. Gelletly
A systematic study of the β-decay of neutron-deficient nuclei has been carried out and has provided spectroscopic information of importance for both nuclear structure and nuclear astrophysics. Following an overview of the most relevant achievements, we focus on the latest results on the β decay of 60Ge and 62Ge. We also summarise our results on the mass excesses in comparison with systematics and a recent measurement. Finally, we present updated half-life trends for Tz = -1/2, -1 and -2 neutron-deficient nuclides.
{"title":"β-decay spectroscopy of neutron-deficient nuclei","authors":"S. Orrigo, B. Rubio, W. Gelletly","doi":"10.1051/epjconf/202327912002","DOIUrl":"https://doi.org/10.1051/epjconf/202327912002","url":null,"abstract":"A systematic study of the β-decay of neutron-deficient nuclei has been carried out and has provided spectroscopic information of importance for both nuclear structure and nuclear astrophysics. Following an overview of the most relevant achievements, we focus on the latest results on the β decay of 60Ge and 62Ge. We also summarise our results on the mass excesses in comparison with systematics and a recent measurement. Finally, we present updated half-life trends for Tz = -1/2, -1 and -2 neutron-deficient nuclides.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"19 1-3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91492145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-15DOI: 10.1051/epjconf/202328401028
J. Lerendegui-Marco, A. Casanovas, V. Alcayne, The nTOF Collaboration
The n_TOF facility has just undergone in 2021 a major upgrade with the installation of its third generation spallation target that has been designed to optimize the performance of the two n_TOF time-of-flight lines. This contribution describes the key features and limitations for capture measurements in the two beam lines prior to the target upgrade and presents first results of (n,γ) measurements carried out as part of the commissioning of the upgraded facility. In particular, the energy resolution, a key factor for both increasing the signal-to-background ratio and obtaining accurate resonance parameters, has been clearly improved for the 20 m long vertical beam-line with the new target design while keeping the remarkably high resolution of the long beamline n_TOF-EAR1. The improvements in the n_TOF neutron beam-lines need to be accompanied by improvements in the instrumentation. A review is given on recent detector R&D projects aimed at tackling the existing challenges and further improving the capabilities of this facility.
{"title":"New perspectives for neutron capture measurements in the upgraded CERN-n_TOF Facility","authors":"J. Lerendegui-Marco, A. Casanovas, V. Alcayne, The nTOF Collaboration","doi":"10.1051/epjconf/202328401028","DOIUrl":"https://doi.org/10.1051/epjconf/202328401028","url":null,"abstract":"The n_TOF facility has just undergone in 2021 a major upgrade with the installation of its third generation spallation target that has been designed to optimize the performance of the two n_TOF time-of-flight lines. This contribution describes the key features and limitations for capture measurements in the two beam lines prior to the target upgrade and presents first results of (n,γ) measurements carried out as part of the commissioning of the upgraded facility. In particular, the energy resolution, a key factor for both increasing the signal-to-background ratio and obtaining accurate resonance parameters, has been clearly improved for the 20 m long vertical beam-line with the new target design while keeping the remarkably high resolution of the long beamline n_TOF-EAR1. The improvements in the n_TOF neutron beam-lines need to be accompanied by improvements in the instrumentation. A review is given on recent detector R&D projects aimed at tackling the existing challenges and further improving the capabilities of this facility.","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84564737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-15DOI: 10.1051/epjconf/202327913001
J. Lerendegui-Marco, V. Babiano-Su'arez, J. Balibrea-Correa, C. Domingo-Pardo, I. Ladarescu, A. Tarifeño-Saldivia, V. Alcayne, D. Cano-Ott, E. Gonz'alez-Romero, T. Mart'inez, E. Mendoza, C. Guerrero, F. Calviño, A. Casanovas, U. Koster, N. Chiera, R. Dressler, E. Maugeri, D. Schumann, The nTOF Collaboration
Neutron capture cross-section measurements are fundamental in the study of astrophysical phenomena, such as the slow neutron capture (s-) process of nucleosynthesis operating in red-giant and massive stars. However, neutron capture measurements via the time-of-flight (TOF) technique on key s-process nuclei are often challenging. Difficulties arise from the limited mass (∼mg) available and the high sample-related background in the case of the unstable s-process branching points. Measurements on neutron magic nuclei, that act as s-process bottlenecks, are affected by low (n,γ) cross sections and a dominant neutron scattering background. Overcoming these experimental challenges requires the combination of facilities with high instantaneous flux, such as n_TOFEAR2, with detection systems with an enhanced detection sensitivity and high counting rate capabilities. This contribution reviews some of the latest detector developments in detection systems for (n,γ) measurements at n_TOF, such as i-TED, an innovative detection system which exploits the Compton imaging technique to reduce the dominant neutron scattering background and s-TED, a highly segmented total energy detector intended for high flux facilities. The discussion will be illustrated with results of the first measurement of key the s-process branching-point reaction 79Se(n,γ).
{"title":"New detection systems for an enhanced sensitivity in key stellar (n,γ) measurements","authors":"J. Lerendegui-Marco, V. Babiano-Su'arez, J. Balibrea-Correa, C. Domingo-Pardo, I. Ladarescu, A. Tarifeño-Saldivia, V. Alcayne, D. Cano-Ott, E. Gonz'alez-Romero, T. Mart'inez, E. Mendoza, C. Guerrero, F. Calviño, A. Casanovas, U. Koster, N. Chiera, R. Dressler, E. Maugeri, D. Schumann, The nTOF Collaboration","doi":"10.1051/epjconf/202327913001","DOIUrl":"https://doi.org/10.1051/epjconf/202327913001","url":null,"abstract":"Neutron capture cross-section measurements are fundamental in the study of astrophysical phenomena, such as the slow neutron capture (s-) process of nucleosynthesis operating in red-giant and massive stars. However, neutron capture measurements via the time-of-flight (TOF) technique on key s-process nuclei are often challenging. Difficulties arise from the limited mass (∼mg) available and the high sample-related background in the case of the unstable s-process branching points. Measurements on neutron magic nuclei, that act as s-process bottlenecks, are affected by low (n,γ) cross sections and a dominant neutron scattering background. Overcoming these experimental challenges requires the combination of facilities with high instantaneous flux, such as n_TOFEAR2, with detection systems with an enhanced detection sensitivity and high counting rate capabilities. This contribution reviews some of the latest detector developments in detection systems for (n,γ) measurements at n_TOF, such as i-TED, an innovative detection system which exploits the Compton imaging technique to reduce the dominant neutron scattering background and s-TED, a highly segmented total energy detector intended for high flux facilities. The discussion will be illustrated with results of the first measurement of key the s-process branching-point reaction 79Se(n,γ).","PeriodicalId":11731,"journal":{"name":"EPJ Web of Conferences","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81801857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-15DOI: 10.1051/epjconf/202328304010
D. Fargion, P. G. De Sanctis Lucentini, M. Khlopov
We discuss recent results on the clustering, composition and distribution of Ultra-High Energy Cosmic Rays (UHECR) in the sky; from the energy of several tens of EeV in the dipole anisotropy, up to the highest energy of a few narrow clusters, those of Hot Spots. Following the early UHECR composition records deviations from proton we noted that the UHECR events above 40 EeV can be made not just by any light or heavy nuclei, but mainly by the lightest ones as He,D, Li,Be. The remarkable Virgo absence and the few localized nearby extragalactic sources, such as CenA, NGC 253 and M82, are naturally understood: lightest UHECR nuclei cannot reach us from the Virgo distance of twenty Mpc, due to their nuclei fragility above a few Mpc distances. Their deflection and smearing in wide hot spots is better tuned to the lighter nuclei than to the preferred proton or heavy nuclei candidate courier. We note that these lightest nuclei still suffer of a partial photodistruction even from such close sources. Therefore, their distruption in fragments, within few tens EeV multiplet chain of events, have been expected and later on observed by Auger collaboration, nearly a decade ago. These multiplet presences, strongly correlate with the same CenA, NGC253 sources. The statistical weight of such correlation is reminded. We conclude that the same role of NGC 253 clustering at lower energies could also feed the Auger dipole anisotropy at lower energy ranges. Such lower energy anisotropy could be fed and integrated by nearest Vela, Crab, LMC and Cas A contributes. In our present UHECR model, based on lightest nuclei in local volumes of a few Mpcs, closest AGN, Star-Burst or very close SNR are superimposing their signals, frozen in different epochs, distances and directions, feeding small and wide anisotropy. Possible tests to confirm, or untangle the current model from alternative ones, are suggested and updated.
我们讨论了超高能量宇宙射线(UHECR)在天空中的聚集、组成和分布的最新结果;从偶极子各向异性中几十EeV的能量，到少数窄团的最高能量，即热点的能量。根据早期UHECR组成记录与质子的偏差，我们注意到40 EeV以上的UHECR事件不仅可以由任何轻核或重核引起，而且主要由He,D, Li, be等最轻的原子核引起。室女座的显著缺失和附近的少数星系外源，如CenA, NGC 253和M82，自然是可以理解的:最轻的UHECR核不能从室女座20 Mpc的距离到达我们，因为它们的核在几个Mpc距离以上就很脆弱。它们在宽热点上的偏转和涂抹更适合于较轻的原子核，而不是首选的质子或重核候选信使。我们注意到，即使在如此近的光源下，这些最轻的原子核仍然遭受部分光破坏。因此，在几十个EeV的多重事件链中，它们以碎片的形式被破坏，已经在近十年前被俄歇合作预料到，后来也被观察到。这些多重存在与同一个CenA NGC253源密切相关。提醒了这种相关性的统计权重。我们得出的结论是，NGC 253在较低能量的星系团的同样作用也可以在较低能量范围内提供俄歇偶极子各向异性。这种较低能量的各向异性可以被最近的Vela、Crab、LMC和Cas A贡献补充和整合。在我们目前的UHECR模型中，基于几个Mpcs局部体积中最轻的核，最近的AGN，星爆或非常接近的信噪比叠加它们的信号，冻结在不同的时代，距离和方向，产生小而宽的各向异性。建议并更新可能的测试，以确认或从替代模型中理清当前模型。
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