scholarly journals First Results of the 140Ce(n,γ)141Ce Cross-Section Measurement at n_TOF

Universe ◽  
2021 ◽  
Vol 7 (6) ◽  
pp. 200
Author(s):  
Simone Amaducci ◽  
Nicola Colonna ◽  
Luigi Cosentino ◽  
Sergio Cristallo ◽  
Paolo Finocchiaro ◽  
...  
Keyword(s):  
Cross Section ◽  
Globular Clusters ◽  
Liquid Scintillator ◽  
Nuclear Data ◽  
P Wave ◽  
Accurate Analysis ◽  
Significant Difference ◽  
Experimental Apparatus ◽  
First Results ◽  
Scintillator Detectors

An accurate measurement of the 140Ce(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 140Ce capture cross-section due to a lack of accurate nuclear data. For this measurement, we used a sample of cerium oxide enriched in 140Ce 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 140Ce Maxwellian-averaged cross-section.

scholarly journals Cross section measurement of 241Am(n,f) reaction at the Experimental Area 2 of the n_TOF facility at CERN: First Results

2020 ◽  
Vol 27 ◽  
pp. 189
Author(s):  
Zinovia Eleme ◽  
... Et al.
Keyword(s):  
Cross Section ◽  
Nuclear Waste ◽  
Energy Production ◽  
Nuclear Data ◽  
Reaction Cross ◽  
Β Decay ◽  
Experimental Area ◽  
High Production Rate ◽  
First Results ◽  
Set Up

The condition for the safe design and operation of fast neutron reactors and energy boosters (Generation-IV reactors, ADS systems [1]) is the accuracy of nuclear data. The 241Am isotope (T1/2 = 433 years) is highly present in nuclear waste, accounting for about 1.8% of the actinide mass in PWR UOx nuclear reactors’ waste [2]. In addition, the 241Am isotope is further produced by the β decay of the 241Pu isotope (T1/2 = 14.3 years). Given the high production rate of 241Am isotope, its incineration with concurrent energy production is considered to be of utmost importance for the design and implementation of the recycling of existing nuclear waste. Sensitivity studies of the proposed systems for energy production showed that high-precision measurements of the cross section of the 241Am(n,f) reaction are required. In the present work, the 241Am(n,f) reaction cross section was measured in the Second Experimental Area of the n_TOF facility at CERN, using an array of Micromegas detectors. For the measurement, six targets of 241Am with average activity of 17 MBq per sample were coupled with an equal number of detectors in a common chamber. Additionally two 235U and two 238U samples were coupled with Micromegas detectors utilizing the neutron flux determination. Within this work, an overview of the experimental set-up and the adopted data analysis technique is presented along with preliminary results.

Out-of-Plane Pipe Whip for a Bent Cantilever Pipe: Comparison Between Experiment and FEM Models

2011 ◽  
Vol 79 (1) ◽  
Author(s):  
S. R. Reid ◽  
M. Aleyaasin ◽  
B. Wang
Keyword(s):  
Cross Section ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Plastic Response ◽  
Nonlinear Dynamic Model ◽  
Accurate Analysis ◽  
Shell Elements ◽  
Rigorous Approach ◽  
Significant Difference ◽  
Out Of Plane

The three-dimensional, dynamic, elastic-plastic response of a right-angle bent cantilever pipe, with an initially uniform, circular cross section, subjected to out-of-plane loading is examined using finite element beam and shell models in ABAQUS. The large-deflection behavior involves both bending and torsional elastoplastic deformations of the pipe, phenomena which have not been previously studied in the context of the dynamic problem of pipe whip. Initially, neglecting ovalization and local collapse (kinking), the bent pipe is modeled as a beam, using spatial beam elements in ABAQUS. This enables the basic three-dimensional kinematic behavior of the pipe to be analyzed. A similar, but potentially more accurate, analysis was then performed using shell elements. It is shown that there is no significant difference in the global dynamic plastic response. However the ovalization of the pipe cross section and formation and movement of the plastic zones (hinges) can be captured by using shell elements. This provides data which could form the basis for examining local failures in the pipe run. Previously unpublished experimental results, obtained in an earlier study by some of the present authors, are compared with the simulated results. Good agreement is observed and it is concluded that a nonlinear dynamic model using finite elements provides a rigorous approach for estimating the hazard zone (HZ) and, also, for treating the kinematics of a whipping pipe for this complex three-dimensional situation.

THE ABSORPTION OF HIGH-ENERGY RADIATION, A MONTE CARLO STUDY: II. SPHERICAL GEOMETRY

1963 ◽  
Vol 41 (4) ◽  
pp. 651-663
Author(s):  
N. R. Steenberg
Keyword(s):  
Cross Section ◽  
Spherical Geometry ◽  
Monte Carlo Study ◽  
Nuclear Data ◽  
High Energy ◽  
Rare Gas ◽  
Nuclear Radius ◽  
Rigid Spheres ◽  
High Energy Radiation ◽  
The Individual

The absorption of radiation in a spherical obstacle composed of rigid spheres has been studied. The result is the absorption cross section of such an obstacle as a function of the free cross section and the number A of the individual spheres and of packing density. It is found that the usual rare-gas formula represents the cross section adequately. The analysis is applied to nuclear data for the absorption of 25-Bev/c protons by nuclei. It is found that for a nuclear radius R = r0A1/3 + δ, where δ is the radius of the nucleon, r0 = 1.17 fermi, δ = 1.05 fermi, and an average nucleon transparency a2 = 0.30 is consistent with the data.

scholarly journals Impaired atrial electromechanical coupling in lichen planus patients

2021 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
I Jafaripour ◽  
Z Aryanian ◽  
S Hosseinzadeh ◽  
R Pourkia ◽  
MM Ansari Ramandi ◽  
...  
Keyword(s):  
Lichen Planus ◽  
Electromechanical Coupling ◽  
Wave Dispersion ◽  
Tissue Doppler ◽  
P Wave ◽  
Control Group ◽  
P Value ◽  
P Wave Dispersion ◽  
Increased Risk ◽  
Significant Difference

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Lichen planus (LP) which is a chronic inflammatory disease can cause impaired atrial electromechanical coupling, leading to increased risk of atrial fibrillation. Purpose The present study aimed to evaluate atrial electromechanical coupling in LP patients by using electrocardiography (ECG) and echocardiography. Methods Forty-six LP patients were investigated in this cross-sectional case-control study. The control group comprised healthy individuals selected in age and gender-matched manner. Echocardiography and ECG were done for all patients to show inter and intra-atrial electromechanical delays and P wave dispersion respectively. The electromechanical delays were calculated by using the difference between the delays from the onset of the P wave on ECG to the onset of A wave on tissue Doppler recordings of the different areas. Results The baseline characteristics of the case and control group were similar and did not differ significantly. The P wave dispersion was 45.63 ± 3.48 milliseconds in the LP group in comparison to 36.56 ± 2.87 milliseconds in the control group (p < 0.001). As shown in the table, the intra and inter-atrial electromechanical delays were also significantly prolonged in LP patients when compared to the control group (p < 0.001). There was no significant difference between the left and right ventricular systolic function and diastolic function of the two groups. Conclusion The results of the study indicate the presence of significant impaired atrial electromechanical coupling in patients with LP confirmed by both electrocardiographic and echocardiographic tools. Electromechanical delays Case N = 46 (mean ± SD) Control N = 46 (mean ± SD) P value Septal - PA (msec) 59.71 ± 13.24 44.39 ± 11.07 0.002 Lateral - PA (msec) 55.71 ± 13.26 48.89 ± 11.21 0.009 Tricuspid - PA (msec) 52.37 ± 13.12 43.28 ± 10.58 0.002 Inter-atrial delay (msec) (lateral PA−RV PA) 8.47 ± 1.62 6.37 ± 1.36 <0.001 Intra-atrial delay (msec) (LA) [lateral PA−septal PA] 4.80 ± 1.48 3.83 ± 0.82 <0.001 Intra-atrial delay (msec) (RA) [septal PA−RV PA] 3.91 ± 0.96 2.02 ± 0.71 <0.001 PA Delay from the onset of the P wave on ECG to the onset of A wave on tissue Doppler, N: number, SD: Standard Deviation, LA: Left Atrium, RA: Right Atrium, RV: Right Ventricle

RISK PREDICTION FOR ARRHYTHMIA IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE

2021 ◽  
Vol 74 (10) ◽  
pp. 2605-2609
Author(s):  
Tetyana M. Ternushchak ◽  
Marianna I. Tovt-Korshynska
Keyword(s):  
P Wave ◽  
Doppler Imaging ◽  
Control Group ◽  
Chronic Obstructive ◽  
Conduction Time ◽  
Electromechanical Delay ◽  
P Wave Dispersion ◽  
Atrial Electromechanical Delay ◽  
Copd Patients ◽  
Significant Difference

The aim: To evaluate P-wave dispersion (PwD), as an independent predictor of atrial fibrillation, corrected QT interval dispersion (cQTD), the noninvasive marker of ventricular arrhythmia and sudden cardiac death, investigate the atrial electromechanical delay in patients with COPD and assess their relation with the severity of the disease. Materials and methods: We prospectively enrolled consecutive patients with newly diagnosed COPD (n = 53, age 41.2 ± 6.8 years), compared with an age-matched healthy control group (n = 51, age 40.9 ± 6.5 years). A standard 12-lead electrocardiogram of each patient was analyzed for PwD and сQTD. Atrial electromechanical delay was analyzed by echocardiographic tissue Doppler imaging. The difference between PAs-PAl, PAs-PAt, and PAl-PAt were defined as left intra-atrial, right intra-atrial, and interatrial electromechanical delays (EMD), respectively. Results: PwD was higher in COPD patients than in control subjects (39.47 ± 3.12 ms vs. 30.29 ± 3.17 ms, p < 0.05). In comparison between control group and COPD subgroups (mild, moderate and severe), there was a statistically significant difference among these free groups in terms of PwD. Subgroup analyses showed that this difference was mainly due to patients with severe COPD. Regarding cQTD, there was a statistically significant increase in COPD patients 57.92 ± 3.43 ms vs 41.03 ± 5.21 ms, p < 0.05 respectively. PAs, PAl and PAt durations, right intra-atrial and interatrial EMD were also significantly longer in COPD patients (p < 0.05). Furthermore, there were significant negative correlations between FEV1 and PwD (r = – 0.46, p < 0.05), right intra-atrial (r = – 0.39 ms, p < 0.05), interatrial EMD ( r = – 0.35 ms, p < 0.05) and cQTD (r = – 0.32, p < 0.05). Conclusions: Atrial conduction time, such as inter- and intra-atrial EMD intervals, PwD and cQTD were longer than in healthy controls and correlated with the severity of COPD. These parameters offer a non-invasive and cost-effective assessment method for detecting patients at high risk of arrhythmia. Nevertheless, further prospective investigations on this issue are required.

Cross Section and Fission Yields Induced Uncertainty in the Vver-440 Burnup Calculation

2021 ◽  
Author(s):  
Branislav Vrban ◽  
Stefan Cerba ◽  
Jakub Luley ◽  
Filip Osuský ◽  
Vladimir Necas
Keyword(s):  
Cross Section ◽  
Neutron Cross Section ◽  
Nuclear Data ◽  
Reactor Operation ◽  
Precise Estimation ◽  
Stochastic Techniques ◽  
Core Characteristics ◽  
Fission Yields ◽  
Operational Data ◽  
Burnup Calculation

Abstract The properties of nuclear fuel depend on the actual isotopic composition which develops during a reactor operation. In practice, the prediction accuracy of burnup calculations serves as the basis for the future precise estimation of a core lifetime and other safety-based core characteristics. The present study quantifies nuclear data induced uncertainties of nuclide concentrations and multiplication factors in VVER-440 fuel depletion analysis. The well-known SCALE system and the TRITON sequence are used with the NEWT deterministic solver in the SAMPLER module that implements stochastic techniques to assess the uncertainty in computed results. The propagation of uncertainties in neutron cross section and fission yields is studied through the depletion calculation of 2D heterogeneous VVER-440 fuel assembly with an average enrichment of 4.87 wt % of 235U and six gadolinium rods with 3.35 % of Gd2O3. In the paper, fixed nominal depletion conditions are based on the real operational data of the Slovak NPP Bohunice unit 4 during cycle 30. In total 250 cases with uncertain parameters are computed and the results are evaluated by an auxiliary tool.

THE ANOMALOUS PROCESS γπ → ππ AND ITS IMPACT ON THE π0 TRANSITION FORM FACTOR

2014 ◽  
Vol 35 ◽  
pp. 1460397
Author(s):  
BASTIAN KUBIS
Keyword(s):  
Form Factor ◽  
Phase Shift ◽  
Theoretical Analysis ◽  
Cross Section ◽  
Transition Form Factor ◽  
P Wave ◽  
Chiral Anomaly ◽  
Transition Form ◽  
Dispersive Representation ◽  
Important Input

The process γπ → ππ, in the limit of vanishing photon and pion energies, is determined by the chiral anomaly. This reaction can be investigated experimentally using Primakoff reactions, as currently done at COMPASS. We derive a dispersive representation that allows one to extract the chiral anomaly from cross-section measurements up to 1 GeV, where effects of the ρ resonance are included model-independently via the ππ P-wave phase shift. We discuss how this amplitude serves as an important input to a dispersion-theoretical analysis of the π0 transition form factor, which in turn is a vital ingredient to the hadronic light-by-light contribution to the anomalous magnetic moment of the muon.

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