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The Borexino detector at Gran Sasso has now accumulated over ten years of continuous data which represent a magnificent opportunity to study the cosmic muon flux at a deep underground location. We present here a precision measurement of the flux and of the expected seasonal modulation. We present the correlation with the atmospheric temperature variations from global atmospheric models. We measure the correlation parameters and infer the kaon-to-pion ratio in the production of cosmic muons from high energy primaries. We also find evidence of a long term modulation that is not present in the atmospheric data and we investigate a possible positive correlation with the solar activity. Finally we observe a seasonal modulation of the production rate of cosmogenic neutrons that is in phase with the muon modulation but shows a surprisingly larger amplitude.

Borexino is a 280-ton liquid scintillator detector located at the Laboratori Nazionali del Gran Sasso (LNGS), Italy and is one of the two detectors that has measured geoneutrinos so far. The unprecedented radio-purity of the scintillator, the shielding with highly purified water, and the placement of the detector at a 3800 m w.e. depth have resulted in very low background levels and has made Borexino an excellent apparatus for geoneutrino measurements. The new update of the Borexino geoneutrino measurement, using the data obtained from December 2007 to April 2019, has been presented. Enhanced analysis techniques, adopted in this measurement, have been also presented (poster presentation #39 by S. Kumaran). The updated statistics and the new elaborate analysis have led to more than a factor two increase in exposure ((1.12 ± 0.05) × 1032 protons × yr) when compared to the latest Borexino result from 2015. The resulting geoneutrino signal of 47.0 − 7.7 + 8.4 ( stat ) − 1.9 + 2.4 ( sys ) TNU has − 17.2 + 18.3 % total precision. The geological interpretations of this measurement have been discussed. In particular, the 99% C.L. observation of the mantle signal by exploiting the relatively well-known lithospheric contribution, the estimation of the radiogenic heat, as well as the comparison of these results to the predictions based on different geological models. The upper limits on the power of a hypothetical georeactor that might be present at different locations inside the Earth have been set.

Fe–Co-based soft magnetic alloys with excellent magnetic properties were prepared by metal injection moulding and hot isostatic pressing. The effect of processing parameters on microstructure and magnetic properties of the alloy were investigated. Good magnetic performance of Fe-50 %Co alloy with a maximum permeability of 9550, saturation induction of 2.42 T, and coercive force of 68.14 A m–1 was achieved. Hot isostatic pressing processing resulted in a near-full density and the achieved saturation induction exceeded the reported value (1.99 to 2.26 T) of Fe-50 %Co produced by metal injection moulding.

Thanks to the progress of neutrino physics, today we are able of exploiting neutrinos as a tool to study astrophysical objects. The latter in turn serve as unique sources of elusive neutrinos, which fundamental properties are still to be understood. This contribution attempts to summarize the latest results obtained by measuring neutrinos emitted from the Sun and geoneutrinos produced in radioactive decays inside the Earth, with a particular focus on a recent discovery of the CNO-cycle solar neutrinos by Borexino. Comprehensive measurement of the pp-chain solar neutrinos and the first directional detection of sub-MeV solar neutrinos by Borexino, the updated 8B solar neutrino results of Super-Kamiokande, as well as the latest Borexino and KamLAND geoneutrino measurements are also discussed.

Borexino is a 280t liquid scintillator detector at the Laboratori Nazionali del Gran Sasso (LNGS), Italy. Its main goal is the precision spectroscopy of solar neutrinos down to energies of 0.19 MeV and for this task it features an unprecedented radio-purity and a high scintillation light yield. The solar neutrinos are measured by the elastic scattering off electrons which induce isotropically emitted scintillation photons as well as a sub-dominant number of Cherenkov photons that are detected by photomulitplier tubes. Here we present the first detection of sub-MeV solar neutrinos using their associated Cherenkov photons in a high light yield liquid scintillator detector. In Borexino electrons with E>0.16MeV produce Cherenkov photons, where the ratio of Cherenkov photons from the neutrino scattered electrons is estimated to be < 1% for all PMT hits, so a typical event by event direction reconstruction is not possible. Instead this analysis looks at the integrated signal of the PMT hits of all detected events by correlating the position of each hit PMT relative to the reconstructed position of the event and the well known position of the Sun. In this way it is possible to measure an angular distribution that shows the statistical contribution of Cherenkov photons from the solar neutrino recoil electrons. Using the Geant4-based Borexino Monte Carlo to produce the expected angular distribution for solar neutrinos and background we have measured 8643 − 2058 +2252 neutrino events out of 19904 total events for an energy region around the 7Be edge between 0.53 MeV and 0.74 MeV.

The Borexino detector, located at the Laboratori Nazionali del Gran Sasso in Italy, is a radiopure 280 ton liquid scintillator detector with a primary goal to measure low-energy solar neutrinos created in the core of the Sun. These neutrinos are a consequence of nuclear fusion reactions in the solar core where Hydrogen is burned into Helium and provide a direct probe of the energy production processes, namely the proton-proton (pp) chain and the Carbon-Nitrogen-Oxygen (CNO) cycle. The fusion of Hydrogen in the case of the CNO cycle, which is expected to contribute in the order of less than 1% to the total solar energy, is catalyzed by Carbon, Nitrogen, and Oxygen directly depending on the abundances of these elements in the solar core. The measurement of CNO neutrinos is challenging due to the high spectral correlation with the decay electrons of the background isotope 210Bi and the pep solar neutrino signal. The experimental achievement of thermal stabilization of the Borexino detector after mid 2016, has opened the possibility to develop a method to constrain the 210Bi rate through its decay daughter and α emitter 210Po which can be identified in Borexino with an efficiency close to 100 percent on an event-by-event basis. Moreover, the flux of pep neutrinos can be constrained precisely through a global analysis of solar neutrino data which is independent of the dataset used for the CNO analysis. This conference contribution is dedicated to the first experimental evidence of neutrinos produced in the CNO fusion cycle in the Sun which is at the same time the dominant energy production mechanism in heavier stars compared to the Sun.

Thermal deformation behaviors and microstructure evolution of a novel light refractory high-entropy alloy (RHEA) TiAlVNb2 were investigated in detail. Uniaxial compression was implemented at different strain rates from 10−3 s − 1 to 10−1 s − 1 and various temperatures from 1000 °C to 1200 °C . Stress-strain curves combined with electron back scattered diffraction analysis indicate that work hardening, dynamic recrystallization (DRX) and dynamic recovery (DRV) occur during the thermal compression. Flow stress analysis carried out by the Arrhenius-type power law relationship suggests a high apparent activation energy of 401–375 kJ ∙ mol − 1 over the whole range of strain. The DRX acts as one of the main softening mechanisms, in which the DRX grains show a typical trend of increased size and fraction with increased temperature or/and decreased strain rate. Further analyses, however, reveal a unique DRX feature that both discontinuous and continuous DRX processes take place in this RHEA. The discontinuous DRX was proved by bulge (migration) of original grain boundaries, kernel average misorientation map and transmission electron microscopy; while the cumulative misorientation (point to origin) and the new grains formed at original grain interior support the existence of continuous DRX (CDRX).

Due to the excellent structural and functional properties, such as low density, high fracture toughness and fatigue strength, Al-Cu-Mg (2024 aluminum) alloy has become an attractive light weight material for inertial instruments and aerospace applications. However, it has relatively low dimensional stability. The aim of this investigation is to enhance the dimensional stability of 2024 aluminum alloy via two-stage aging method, and identify the precipitation behavior and the underlying stabilizing mechanisms of 2024 aluminum alloy. When the second aging time was 24 h, the uniformly distributed precipitates could effectively pin the dislocations and impede their movement. This leaded to a significant improvement of the micro-yield strength and the thermal strain in the 2024 aluminum alloy, and thus the dimensional stability of the alloy increased.

AlNb2TiV, a novel, light-weight, refractory high-entropy alloy (RHEA), with high specific strength and excellent room-temperature deformability is identified. As cast, it has a dendritic microstructure with an ordered B2 phase, low density (~6.19 g/cm3), excellent specific yield strength (167 MPa*cm3/g) and deformability (strain >1.0 in compression). Slip occurs by glide of 1/2〈1 1 1〉 dislocations. Based on previous work, the Ti/Nb ratio of our RHEA falls in the optimal range for easy dislocation motion and good deformability.

Phosphorus powder was used to improve the performance of iron based alloy products fabricated by metal injection molding. Seven kinds of Fe–xP soft magnetic alloys were formed using carbonyl iron powder and Phosphorus powder as raw materials where x=0–1.2 wt% with 0.2 wt% increment. Samples were sintered in hydrogen atmosphere at the temperature range of 1100–1450 °C for varied times. The effects of sintering temperature and time on the density, microstructure and magnetic properties like magnetic induction, maximum permeability and coercive force of the alloys were examined. The results demonstrated that better magnetic performances of the injection molded Fe–xP alloy is due to increased density of the sintered compacts because of formation of liquid phase at low temperature. For Fe–0.8%P alloy, optimum density 7.84 g/cm 3 (relative density 99%) and magnetic induction (B 6000 ) 1.77 T, maximum permeability 17,100 were obtained at sintering temperature 1420 °C while the coercive force was 21 A/m respectively.

Influences of Cr content and post weld heat treatment (PWHT) on microstructure and oxidation behavior of stainless steel cladding materials in high temperature water were investigated. The amounts of metal oxidized and dissolved were estimated to compare the oxidation behaviors of cladding materials with different Cr contents and PWHT. The results indicated that higher Cr content led to formation of more ferrite content, and carbides were found along δ/γ phase interface after PWHT. Higher Cr content enhanced the pitting resistance and compactness of the oxide film to reduce metal amount oxidized and dissolved, which mitigated the weight changes and the formation of Fe-rich oxides. PWHT promoted more and deeper pitting holes along the δ/γ phase interface due to formation of carbides, which resulted in an increase in metal amount oxidized and dissolved, and were also responsible for more Fe-rich oxides and higher weight changes.

The microstructure formation process in Co–Al–W–Ti alloys was investigated through quenching performed during directional solidification. The phase transition route of the Co–Al–W–Ti alloys during directional solidification is determined as follows: L → L + γ → L + γ + (β + γ′) → L + γ + γ′ + (β + γ′) → γ + γ′ + β + (β + γ′). The eutectic (β + γ′), primary γ′ and β are orderly deposited in terminal stages of solidification. The eutectic γ′ and β are well distributed and nucleate in random directions. The γ′ particles are precipitated initially from the interdendritic Al-rich regions and subsequently from the dendritic region. The sizes of the γ′ particles close to the primary γ′ and β phases are greater than that of the particles far from them. Since the growth of eutectic colonies restricts the interdendritic liquid convection at earlier stage of the terminal solidification, Co–Al–W–Ti alloys are resistant to the grain defect formation and suitable for fabricating single crystal components.

Metal injection molding (MIM) is a process that has the predominance in the economical mass production of minisize, complex shaped soft magnetic parts. However, not full dense materials could have their density dependent properties as magnetic induction decreases, and also generated microstructure can be affected, showing large pores, that could act as domain-wall barriers reducing soft magnetic performance. This study overcame this problem and obtained high magnetic property and full density Fe-79%Ni-4%Mo alloy by MIM, hot isostatic pressing and subsequent heat treatment. The maximum permeability, saturation induction and coercive force are 210,000, 0.862 T and 0.95 A/m, respectively. The relationships between processing parameters, density, stress, microstructure and magnetic properties were investigated. The results revealed that maximum permeability was more sensitive to stress and magnetic performance was strongly influenced by density and microstructure.

The γ′ solvus temperature is essential for high temperature microstructural stability and strengthening of the newly developed Co–Al–W-base alloys, but few were above 1100 °C since their discovery. In the current study, two experimental alloys containing both Ti and Ta were reported to have high γ′ solvus temperatures of 1131 and 1157 °C, respectively. Typical γ/γ′ two-phase microstructure with high volume fraction of γ′ precipitates presented after aging at high temperature above 1100 °C in two experimental alloys. Furthermore, the γ/γ′ microstructure still remained with a γ′ volume fraction about 63% and no formation of secondary phase at 1050 °C for 1000 h. This work indicates the promising microstructural stability to further develop this class of Co-base alloys.

The lamellar microstructure of TiAl–Nb alloys with and without low boron additions is controlled using double directional solidification (DS). In alloys without the addition of boron, the β phase is seeded during double DS. Complete peritectic transformation occurs in both the dendritic and interdendritic regions, which can lead to the successful alignment of both the high-temperature α phase and the lamellar microstructures. Well-aligned lamellar microstructures can be easily achieved if the alloy composition is close to the peritectic point on the hypo-peritectic side. In alloys with low boron additions, however, the competitive growth of the α phase breaks the continuity of the lamellar microstructure in the region ahead of stable growth, which finally results in columnar grain coarsening and unsuccessful alignment of the lamellar microstructures.

Aim To evaluate the image quality and dose reduction capability of non-enhanced chest computed tomography (CT) examinations using iterative reconstruction in image space (IRIS). Materials and methods A CT water phantom was scanned at 120kV/150mAs and 100kV/270mAs as the reference, and the tube current was decreased in 10% intervals down to 40% of the reference value. Image noise was evaluated and compared between filtered back-projection (FBP) and IRIS reconstructed data. In the patient study, 90 patients underwent non-enhanced chest CT examinations; the patients were randomly assigned into three groups: group A ( n =30) standard dose protocol, 120kV/110mAs; group B ( n =30) low dose, 100kV/110mAs; group C ( n =30) low dose, 120kV/67mAs. All images were reconstructed by FBP and IRIS algorithm using matched kernels of B30 and I30. The objective image noise (OIN), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of the aorta and latissimus dorsi were measured. The subjective image quality and noise were scored using a three-point scale by two experienced radiologists. The results of the subjective and objective image assessment were compared between groups B and C (low dose) IRIS and group A (standard dose) FBP. Results The phantom study showed comparable image noise between the scans using 60% dose with IRIS and 100% dose with FBP for both 120 and 100kV. In the patient study, groups A, B, and C had effective dose of 3.81±0.43, 2.40±0.19, and 2.41±0.15mSv. IRIS significantly improved the OIN, SNR, and CNR compared with FBP for the same patient. The OIN, SNR, and CNR using IRIS in group B and C were improved or comparable to those in group A using FBP. No significant difference was found in subjective image quality and noise between groups B and C using IRIS and group A using FBP. Conclusion Compared with FBP, IRIS can maintain or improve image quality on unenhanced chest CT image reconstruction while saving 40% radiation dose.

A closely-complete peritectic transformation (PT) was found during directional solidification (DS) of a Ti-45Al-8.5Nb alloy under a low temperature gradient. The closely-complete PT can align the peritectic α phase and control the lamellar orientation. The conditions to obtain a complete PT in primary β TiAl alloys were theoretically evaluated in the dendrite regime.

Lamellar microstructures of the Ti–46Al–5Nb alloy solidifying through the primary β phase were successfully aligned parallel to the growth direction by using the double directional solidification (DS) technique. The same growth conditions in both DS processes and the completion of the peritectic transformation in the dendritic regions are necessary for the primary β phase TiAl alloys to control the lamellar orientation.

Intermetallic Ti–45Al–8.5Nb–(W, B, Y) alloys were directionally solidified at constant growth rates (V) ranging from 10 to 400 μm/s under the temperature gradient G = 3.8 × 103 K/m. Quenching was performed at the end of directional solidification (DS) experiments. Microstructure evolution was investigated by analyzing the microstructures formed at the quenching interfaces and in the DS regions. The primary dendritic arm spacing (λ) decreases with increasing growth rate according to the relationship λ ∝ V−0.36. Both the width of columnar grain ( λ w ) and the interlamellar spacing (λs) decrease with increasing growth rate according to the relationships λ w ∝ V − 1.13 and λs ∝ V−0.32, respectively. Lamellar microstructure initially disappears from the dendrites at the growth rate of 100 μm/s and subsequently from the interdendritic regions when the growth rate is up to 200 μm/s. The B2 particles can precipitate in the interdendritic regions.

Intermetallic Ti–45Al–8Nb–(W, B, Y) (at.%) alloys were directionally solidified at growth rates of 10–400 μm/s with a Bridgeman type apparatus. Microstructures and room temperature (RT) mechanical properties of the directionally solidified (DS) alloys were investigated. The microstructures with different segregation morphologies were observed at different growth rates. Fully lamellar (FL) microstructure evolves into a massive microstructure when the growth rate is up to 100 μm/s. Both the width of columnar grain and the interlamellar spacing decrease with increasing growth rate. Compressive properties were not proportional to the growth rates but closely related to the segregation morphologies. Only the DS alloy with columnar pattern of Al-segregation had tensile ductility. A better RT tensile plastic elongation level of 2% and yield strength 475 MPa were obtained at growth rate of 10 μm/s. Cracks propagated in transgranular mode predominantly. Larger elongated B2 particles produced in the interdendritic regions were detrimental to the tensile ductility of the DS alloy.

Microstructure development and phase transition were investigated by quenching during directional solidification (DS) of Ti–45Al–8Nb (at.%) alloy. The solidification route and process can be controlled by adjustment of the solidification condition. A coexisted region of L + β + α was found at a low growth rate. The high temperature α phase, produced by peritectic transformation or β → α solid-state transformation or direct solidification from interdendritic liquid, was determined by the solidification conditions and can be identified by checking the β-segregation pattern in dendritic region. Lamellar orientation control was achieved when the interdendritic α grew on the top of peritectically formed α. High temperature α can be aligned continuously although α partly grew from the region of primary β interdendrite. Some elongated B2 particles were generated due to β-stablizers were centralized in interdendritic liquid during DS process. The volume fraction of the B2 particle decreased with decreasing growth rate ( V ).