CMB-S4: Forecasting Constraints on Primordial Gravitational Waves

CMB-S4---the next-generation ground-based cosmic microwave background (CMB) experiment---is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the Universe, from the highest energies at the dawn of time through the growth of structure to the present day. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semi-analytic projection tool, targeted explicitly towards optimizing constraints on the tensor-to-scalar ratio, $r$, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2--3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments given a desired scientific goal. To form a closed-loop process, we couple this semi-analytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for $r > 0.003$ at greater than $5\sigma$, or, in the absence of a detection, of reaching an upper limit of $r < 0.001$ at $95\%$ CL.Comment: 24 pages, 8 figures, 9 tables, submitted to ApJ. arXiv admin note: text overlap with arXiv:1907.0447

CMB-S4: Forecasting Constraints on Primordial Gravitational Waves

Abstract: CMB-S4—the next-generation ground-based cosmic microwave background (CMB) experiment—is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the universe. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semianalytic projection tool, targeted explicitly toward optimizing constraints on the tensor-to-scalar ratio, r, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2–3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments, given a desired scientific goal. To form a closed-loop process, we couple this semianalytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for r > 0.003 at greater than 5σ, or in the absence of a detection, of reaching an upper limit of r < 0.001 at 95% CL

Characterization and Evaluation of Mechanical Properties of Al-Zn Based Hybrid Metal Matrix Composites

Hybrid aluminium matrix composites are preferred for structural applications due to their tailored material properties. In the current study, aluminium-7029 alloy with boron carbide (5, 10, and 15 wt%) and a constant weight percentage of graphite (5 wt%) were produced by the stir casting route. Scanning Electron Microscope and X-Ray Diffraction were used to characterize the composites. The cast alloy and hybrid composites were evaluated for physical (density and porosity) and mechanical (hardness, tensile, compressive and impact) properties by experimental and statistical methods. The porosity of the cast samples was minimal (&lt;5%) and the hybrid composite weight decreased (2.4%) with the increase of reinforcements as revealed by the density test. Al7029/15wt%B4C/5wt%Gr (sample C3) hybrid composite hardness (126 BHN) and compressive strength (586.841 MPa) were found to be the best to get the better property with more reinforcement. Tensile (253.455 MPa) and impact strength (7 J) were the highest for the Al7029/5wt%B4C/5wt%Gr (sample C1) hybrid composite. Results obtained by a regression model developed using MINITAB were in good agreement with experimental values. The additions of B4C and Gr were found to improve mechanical properties significantly, as confirmed by analysis of variance

Mechanical Characterization of B4C-Gr Al2618 Based Composites Synthesized by Stir Casting Method

Aerospace and automotive industries rely heavily on aluminium alloys because of their advantageous physical and mechanical properties. This paper presents studies on the performance of stir cast B4C (Boron carbide) and Gr (graphite) reinforced aluminium metal matrix composite (AMMC). Particulate reinforcement of B4C and Gr is in the ratio 2:1 (wt.%). Characterization of AMMC's mechanical properties reveals that the composite has enhanced mechanical properties compared to Al2618. Through Scanning electron microscope(SEM), it is identified that microstructure of AMMC and distribution of B4C and Gr particles in Al2618 are found to be uniform. Based on the results of the experiments, it was determined that the best AMMC mixture for improving the material's mechanical properties is a combination of B4C and Gr, with the proportions at 8:4. As a result, the automobile sector stands to benefit greatly from the use of this AMMC in the production of engine components

Advancing the Performance of Ceramic - Reinforced Aluminum Hybrid Composites: A Comprehensive Review and Future Perspectives

Hybrid composites comprising aluminum reinforced with ceramics have surfaced as a potential class of materials that exhibit improved mechanical and thermal characteristics. These composites have a diverse range of applications across multiple industries. The present study offers a thorough examination of recent scholarly investigations pertaining to such composites, with particular emphasis on their mechanical performance, thermal attributes, and interfacial characteristics. This paper offers an extensive evaluation of ceramic-reinforced aluminum composites, along with a discussion of potential solutions and prospects for addressing the existing limitations and challenges. This review explores emerging areas of research, encompassing interface engineering methodologies, sophisticated processing techniques, and the incorporation of innovative reinforcement substances. The present recommendations are geared towards augmenting the efficacy, dependability, and durability of hybrid composites comprising ceramic and aluminum reinforcements

Wear behaviour of hybrid (boron carbide-graphite) aluminium matrix composites under high temperature

Abstract Aluminium MMCs are among the many metal composites and are regarded as progressive engineering materials in numerous industries because of their advantages compared to standard aluminium alloy. Among the reinforcements in MMCs, ceramic particles are preferred for their superior wear resistance, temperature resistance, and adhesion to their matrix, making them a popular choice. This research work has been carried out to synthesise ceramic particle-reinforced aluminium metal matrix composites and to evaluate their tribological properties at different temperatures (50–300℃). Al2618 alloy was selected as the matrix, and boron carbide (B4C) and graphite (Gr) were selected as reinforcements. Hybrid composites are prepared through stir casting by varying the wt.% of B4C and Gr reinforcement particles with a ratio of 3:2. Microstructural observation shows the uniform distribution of B4C and Gr particles throughout the matrix without any agglomeration, and it also exhibits excellent scanning electron microscope (SEM). X-ray diffraction analysis (XRD) was performed to verify the presence of different constituents in the developed material. Samples S4 (Al 2618 + 12 wt.% B4C—8 wt.% Gr) and S5 (Al 2618 + 15 wt.% B4C—10 wt.% Gr) exhibit enhanced wear resistance (16.45%) due to the incorporation of a higher quantity of Gr solid lubricants alongside B4C within the temperature range of 50 to 300℃. The thickness and stability of the glazed layer exhibited adequate resistance to wear

CMB-S4: Forecasting Constraints on Primordial Gravitational Waves

CMB-S4 - the next-generation ground-based cosmic microwave background (CMB) experiment - is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the universe. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semianalytic projection tool, targeted explicitly toward optimizing constraints on the tensor-to-scalar ratio, r, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2-3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments, given a desired scientific goal. To form a closed-loop process, we couple this semianalytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for r > 0.003 at greater than 5σ, or in the absence of a detection, of reaching an upper limit of r < 0.001 at 95% CL

Cmb-s4: forecasting constraints on primordial gravitational waves

CMB-S4—the next-generation ground-based cosmic microwave background (CMB) experiment—is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the universe. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semianalytic projection tool, targeted explicitly toward optimizing constraints on the tensor-to-scalar ratio, r, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2–3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments, given a desired scientific goal. To form a closed-loop process, we couple this semianalytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for r > 0.003 at greater than 5σ, or in the absence of a detection, of reaching an upper limit of r < 0.001 at 95% CL