Sliding wear behavior of WC-Co-Cr3C2-VC composites fabricated by conventional and non-conventional techniques

[EN] The present work aims are to study the dry sliding wear behavior of WC-12 wt.%Co materials, with or without addition of Cr3C2/VC grain growth inhibitors, and to sinter them by two different consolidation techniques: conventional sintering and spark plasma sintering (SPS). The dry sliding wear tests were performed on a tribometer with a ball-on-disc configuration using a WC-Co ball as a counterpart material with a normal contact load of 60 N, a sliding distance of 10000 m and a sliding speed of 0.1 m/s. The influence of the grain growth inhibitors and the consolidation techniques in sintered samples were related to the friction coefficient, wear rates and wear pattern damage. Samples sintered by non-conventional technique (SPS) show the best wear resistance and lower friction coefficient. The addition of inhibitors reduces the wear rates in materials consolidated by both techniques. The differences in the wear damage are related to microstructural parameters, mechanical properties and wear ratesThe work is supported financially by the Spanish Ministry of Science and Innovation by the project MAT2009-14144-C03-C02. L. Espinosa-Fernández, acknowledges the AECI program for the realization of the Ph.D in the ITM-UPV. A. Borrell, acknowledges the Spanish Ministry of Science and Innovation for her Juan de la Cierva contract (JCI-2011-10498)Espinosa-Fernández, L.; Borrell Tomás, MA.; Salvador Moya, MD.; Gutierrez-González, C. (2013). Sliding wear behavior of WC-Co-Cr3C2-VC composites fabricated by conventional and non-conventional techniques. Wear. 307:60-67. https://doi.org/10.1016/j.wear.2013.08.00S606730

Sliding wear behavior of Al2O3-NbC composites obtained by conventional and nonconventional techniques

[EN] This study aims to investigate the dry sliding wear behavior of Al2O3 5vol.%NbC nanocomposite sintered by conventional and spark plasma sintering at temperatures from 1450 to 1600 ºC. The tests were performed using WC 6 wt%Co balls as a counterpart material, a load of 30 and 60 N, a sliding distance of 2000 m and a sliding speed of 0.1 m/s. The consolidation techniques influenced the friction coefficient, wear rates and patterns. Samples tested at 30 N showed better wear resistance than the samples tests with 60 N. The nanocomposites obtained by SPS at 1500 ºC exhibited a lower friction coefficient and wear rate compared to all other materials. The results indicated that Al2O3-NbC nanocomposites show promise as material for cutting tool applications.This work has been financial support by the Brazilian institution CAPES for the project CAPES-PVE A086/2013 (project No 23038.009604/2013-12). A. Borrell acknowledges the Spanish Ministry of Economy and Competitiveness for her Juan de la Cierva-Incorporacion contract (IJCI-2014-19839).Ribeiro-Rodrigues Alecrim, L.; Ferreira, J.; Gutierrez-Gonzalez, C.; Salvador Moya, MD.; Borrell Tomás, MA.; Pallone, E. (2017). Sliding wear behavior of Al2O3-NbC composites obtained by conventional and nonconventional techniques. Tribology International. 110:216-221. https://doi.org/10.1016/j.triboint.2017.02.028S21622111

LZS/Al2O3 nanostructured composites obtained by colloidal processing and spark plasma sintering

[EN] Li2O-SiO2-ZrO2 (LZS) glass-ceramics have high mechanical strength, hardness, resistance to abrasion and chemical attack, but also a high coefficient of thermal expansion (CTE), which can be reduced adding alumina nanoparticles. The conventional glass-ceramic production is relatively complex and energy consuming, since it requires the melting of the raw materials to form a glass frit and a two-step milling process to obtain particle sizes adequate for compaction. This study describes the preparation of LZS glass-ceramics through a colloidal processing approach from mixtures of SiO2 and ZrO2 nanopowders and a Li precursor (lithium acetate obtained by reaction of the carbonate with acetic acid). Concentrated suspensions were freeze-dried to obtain homogeneous mixtures of powders that were pressed (100 MPa) and sintered conventionally and by spark plasma sintering. The effect of the alumina nanoparticles additions on suspensions rheology, sintering behavior and properties such as thermal expansion, thermal conductivity, hardness and Young's modulus were evaluated. (C) 2017 Elsevier Ltd. All rights reserved.This work has been supported by Ministerio de Economia y Competitividad (MINECO) and FEDER Funds under grant No MAT2016-67586-C3-R. Authors greatly acknowledge the financial Support of CAPES in the frame of the International Cooperation Program Science without Borders for Special Visiting Researcher PVE (MEC/MCTI/CAPES/CNPQ/FAPs/No 71/2013), Project no. A011/2013. A. Borrell acknowledges the MINECO for her Juan de la Cierva-Incorporacion contract (IJCI-2014-19839).Arcaro, S.; Novaes De Oliveira, A.; Gutierrez-Gonzalez, C.; Salvador Moya, MD.; Borrell Tomás, MA.; Moreno, R. (2017). LZS/Al2O3 nanostructured composites obtained by colloidal processing and spark plasma sintering. Journal of the European Ceramic Society. 37(16):5139-5148. https://doi.org/10.1016/j.jeurceramsoc.2017.03.023S51395148371

Dry-sliding wear behavior of 3Y-TZP/Al2O3-NbC nanocomposites produced by conventional sintering and spark plasma sintering

[EN] This work presents the initial results of the dry-sliding wear behavior of 3 mol% yttria-stabilized zirconia reinforced with 5 vol% alumina-niobium carbide (3Y-TZP/5 vol% Al2O3-NbC) nanocomposites sintered by conventional sintering and spark plasma sintering methods in the temperature range of 1350-1450 degrees C. The reinforcement of 3Y-TZP matrix with hard nanoparticles aimed to improve wear strength of the composites. Wear tests were performed by the ball-on-disc method using alumina (Al2O3) and tungsten carbide with 6 wt% cobalt cermet (WC-6%Co) balls as counter-materials, a load of 15 N, a sliding distance of 2000 m, and a sliding speed of 0.1 m/s. Wear behavior was evaluated in terms of wear rate and FE-SEM micrograph analysis of the wear tracks. The nanocomposite sintered at 1450 degrees C by conventional sintering exhibited the least wear when tested with the WC-6%Co ball. Generally, the wear mechanism showed evidence of severe wear regime with both counter-materials.The authors acknowledge the Brazilian institutions CAPES-PVE (grant number 23038.009604/2013-12), FAPESP (grant number 2015/07319-8), Fundação Araucária (grant number 810/2014), European Union/Erasmus Mundus for doctorate mobility (grant number EB15DM1542), and the Spanish Ministry of Economy and Competitiveness (RYC-2016-20915).Salem, R.; Gutiérrez-González, C.; Borrell Tomás, MA.; Salvador Moya, MD.; Chinelatto, AL.; Chinelatto, AS.; Pallone, E. (2019). Dry-sliding wear behavior of 3Y-TZP/Al2O3-NbC nanocomposites produced by conventional sintering and spark plasma sintering. International Journal of Applied Ceramic Technology. 16(3):1265-1273. https://doi.org/10.1111/ijac.13151S12651273163Liu, H., Zhao, W., Ji, Y., Cui, J., Chu, Y., & Rao, P. (2017). Determination of fracture toughness of zirconia ceramics with different yttria concentrations by SEVNB method. Ceramics International, 43(13), 10572-10575. doi:10.1016/j.ceramint.2017.04.064Ćorić, D., Majić Renjo, M., & Ćurković, L. (2017). Vickers indentation fracture toughness of Y-TZP dental ceramics. International Journal of Refractory Metals and Hard Materials, 64, 14-19. doi:10.1016/j.ijrmhm.2016.12.016De Aza, A. H., Chevalier, J., Fantozzi, G., Schehl, M., & Torrecillas, R. (2002). Crack growth resistance of alumina, zirconia and zirconia toughened alumina ceramics for joint prostheses. Biomaterials, 23(3), 937-945. doi:10.1016/s0142-9612(01)00206-xAragón-Duarte, M. C., Nevarez-Rascón, A., Esparza-Ponce, H. E., Nevarez-Rascón, M. M., Talamantes, R. P., Ornelas, C., … Hurtado-Macías, A. (2017). Nanomechanical properties of zirconia- yttria and alumina zirconia- yttria biomedical ceramics, subjected to low temperature aging. Ceramics International, 43(5), 3931-3939. doi:10.1016/j.ceramint.2016.12.033Balko, J., Csanádi, T., Sedlák, R., Vojtko, M., KovalĿíková, A., Koval, K., … Naughton-Duszová, A. (2017). Nanoindentation and tribology of VC, NbC and ZrC refractory carbides. Journal of the European Ceramic Society, 37(14), 4371-4377. doi:10.1016/j.jeurceramsoc.2017.04.064Alecrim, L. R. R., Ferreira, J. A., Gutiérrez-González, C. F., Salvador, M. D., Borrell, A., & Pallone, E. M. J. A. (2017). Effect of reinforcement NbC phase on the mechanical properties of Al2O3-NbC nanocomposites obtained by spark plasma sintering. International Journal of Refractory Metals and Hard Materials, 64, 255-260. doi:10.1016/j.ijrmhm.2016.10.021Alecrim, L. R. R., Ferreira, J. A., Gutiérrez-González, C. F., Salvador, M. D., Borrell, A., & Pallone, E. M. J. A. (2017). Sliding wear behavior of Al2O3-NbC composites obtained by conventional and nonconventional techniques. Tribology International, 110, 216-221. doi:10.1016/j.triboint.2017.02.028Santos, C., Maeda, L. D., Cairo, C. A. A., & Acchar, W. (2008). Mechanical properties of hot-pressed ZrO2–NbC ceramic composites. International Journal of Refractory Metals and Hard Materials, 26(1), 14-18. doi:10.1016/j.ijrmhm.2007.01.008Ünal, N., Kern, F., Öveçoğlu, M. L., & Gadow, R. (2011). Influence of WC particles on the microstructural and mechanical properties of 3mol% Y2O3 stabilized ZrO2 matrix composites produced by hot pressing. Journal of the European Ceramic Society, 31(13), 2267-2275. doi:10.1016/j.jeurceramsoc.2011.05.032Sequeira, S., Fernandes, M. H., Neves, N., & Almeida, M. M. (2017). Development and characterization of zirconia–alumina composites for orthopedic implants. Ceramics International, 43(1), 693-703. doi:10.1016/j.ceramint.2016.09.216Schmitt-Radloff, U., Kern, F., & Gadow, R. (2017). Wire-electrical discharge machinable alumina zirconia niobium carbide composites – Influence of NbC content. Journal of the European Ceramic Society, 37(15), 4861-4867. doi:10.1016/j.jeurceramsoc.2017.07.014Akatsu, T., Nakanishi, S., Tanabe, Y., Wakai, F., & Yasuda, E. (2013). Toughening enhanced at elevated temperatures in an alumina/zirconia dual-phase matrix composite reinforced with silicon carbide whiskers. Journal of the European Ceramic Society, 33(15-16), 3157-3163. doi:10.1016/j.jeurceramsoc.2013.05.029Lee, D.-J., Choi, H.-S., Jin, F.-L., & Park, S.-J. (2015). A study on mechanical properties and microstructure of tetragonal zirconia-based composites. Journal of Industrial and Engineering Chemistry, 27, 322-328. doi:10.1016/j.jiec.2015.01.008Salem, R. E. P., Monteiro, F. R., Gutiérrez-González, C. F., Borrell, A., Salvador, M. D., Chinelatto, A. S. A., … Pallone, E. M. J. A. (2018). Effect of Al2O3-NbC nanopowder incorporation on the mechanical properties of 3Y-TZP/Al2O3-NbC nanocomposites obtained by conventional and spark plasma sintering. Ceramics International, 44(2), 2504-2509. doi:10.1016/j.ceramint.2017.10.235Schmitt-Radloff, U., Kern, F., & Gadow, R. (2018). Spark plasma sintering and hot pressing of ZTA-NbC materials – A comparison of mechanical and electrical properties. Journal of the European Ceramic Society, 38(11), 4003-4013. doi:10.1016/j.jeurceramsoc.2018.04.022Pędzich, Z., Haberko, K., Faryna, M., & Sztwiertnia, K. (2002). Interphase Boundary in Zirconia – Carbide Particulate Composites. Key Engineering Materials, 223, 221-226. doi:10.4028/www.scientific.net/kem.223.221Acchar, W., Zollfrank, C., & Greil, P. (2004). Microstructure and mechanical properties of WC-Co reinforced with NbC. Materials Research, 7(3), 445-450. doi:10.1590/s1516-14392004000300012Guillon, O., Gonzalez‐Julian, J., Dargatz, B., Kessel, T., Schierning, G., Räthel, J., & Herrmann, M. (2014). Field‐Assisted Sintering Technology/Spark Plasma Sintering: Mechanisms, Materials, and Technology Developments. Advanced Engineering Materials, 16(7), 830-849. doi:10.1002/adem.201300409Munir, Z. A., Anselmi-Tamburini, U., & Ohyanagi, M. (2006). The effect of electric field and pressure on the synthesis and consolidation of materials: A review of the spark plasma sintering method. Journal of Materials Science, 41(3), 763-777. doi:10.1007/s10853-006-6555-2Lu, K. (2008). Sintering of nanoceramics. International Materials Reviews, 53(1), 21-38. doi:10.1179/174328008x254358Borrell, A., Fernández, A., Torrecillas, R., Córdoba, J. M., Avilés, M. A., & Gotor, F. J. (2010). Spark Plasma Sintering of Ultrafine TiCxN1−x Powders Synthesized by a Mechanically Induced Self-Sustaining Reaction. Journal of the American Ceramic Society, 93(8), 2252-2256. doi:10.1111/j.1551-2916.2010.03735.xBonache, V., Salvador, M. D., Fernández, A., & Borrell, A. (2011). Fabrication of full density near-nanostructured cemented carbides by combination of VC/Cr3C2 addition and consolidation by SPS and HIP technologies. International Journal of Refractory Metals and Hard Materials, 29(2), 202-208. doi:10.1016/j.ijrmhm.2010.10.007Gutiérrez-Mora, F., Cano-Crespo, R., Rincón, A., Moreno, R., & Domínguez-Rodríguez, A. (2017). Friction and wear behavior of alumina-based graphene and CNFs composites. Journal of the European Ceramic Society, 37(12), 3805-3812. doi:10.1016/j.jeurceramsoc.2017.02.024Wei, J., Lin, B., Wang, H., Sui, T., Yan, S., Zhao, F., … Fang, S. (2018). Friction and wear characteristics of carbon fiber reinforced silicon carbide ceramic matrix (Cf/SiC) composite and zirconia (ZrO2) ceramic under dry condition. Tribology International, 119, 45-54. doi:10.1016/j.triboint.2017.10.023Fan, H., Hu, T., Zhang, Y., Fang, Y., Song, J., & Hu, L. (2014). Tribological properties of micro-textured surfaces of ZTA ceramic nanocomposites under the combined effect of test conditions and environments. Tribology International, 78, 134-141. doi:10.1016/j.triboint.2014.05.010Gee, M., & Nunn, J. (2017). Real time measurement of wear and surface damage in the sliding wear of alumina. Wear, 376-377, 1866-1876. doi:10.1016/j.wear.2017.01.114Wang, Y., Yang, Y., Zhao, Y., Tian, W., Bian, H., & He, J. (2009). Sliding wear behaviors of in situ alumina/aluminum titanate ceramic composites. Wear, 266(11-12), 1051-1057. doi:10.1016/j.wear.2008.11.006Krell, A. (1996). Improved hardness and hierarchic influences on wear in submicron sintered alumina. Materials Science and Engineering: A, 209(1-2), 156-163. doi:10.1016/0921-5093(95)10155-1Botta F, W. ., Tomasi, R., Pallone, E. M. J. ., & Yavari, A. . (2001). Nanostructured composites obtained by reactive milling. Scripta Materialia, 44(8-9), 1735-1740. doi:10.1016/s1359-6462(01)00789-8Pallone, E. M. J. ., Trombini, V., Botta F, W. ., & Tomasi, R. (2003). Synthesis of Al2O3–NbC by reactive milling and production of nanocomposites. Journal of Materials Processing Technology, 143-144, 185-190. doi:10.1016/s0924-0136(03)00411-4ASTM G99‐03 Standard test method for wear testing with a pin‐on‐disc apparatus ASTM Annual Book of Standards vol.03. West Conshohocken PA;2003.Chen, W.-H., Lin, H.-T., Chen, J., Nayak, P. K., Lee, A. C., Lu, H.-H., & Huang, J.-L. (2016). Microstructure and wear behavior of spark plasma sintering sintered Al2O3/WC-based composite. International Journal of Refractory Metals and Hard Materials, 54, 279-283. doi:10.1016/j.ijrmhm.2015.07.030Espinosa-Fernández, L., Borrell, A., Salvador, M. D., & Gutierrez-Gonzalez, C. F. (2013). Sliding wear behavior of WC–Co–Cr3C2–VC composites fabricated by conventional and non-conventional techniques. Wear, 307(1-2), 60-67. doi:10.1016/j.wear.2013.08.003Bundschuh, W., & Gahr, K.-H. Z. (1991). Influence of porosity on friction and sliding wear of tetragonal zirconia polycrystal. Wear, 151(1), 175-191. doi:10.1016/0043-1648(91)90356-yBayer, R. J. (2004). Mechanical Wear Fundamentals and Testing, Revised and Expanded. doi:10.1201/9780203021798Zum Gahr, K.-H. (1989). Sliding wear of ceramic-ceramic, ceramic-steel and steel-steel pairs in lubricated and unlubricated contact. Wear, 133(1), 1-22. doi:10.1016/0043-1648(89)90109-9Kato, K., & Adachi, K. (2002). Wear of advanced ceramics. Wear, 253(11-12), 1097-1104. doi:10.1016/s0043-1648(02)00240-5Pasaribu, H. R., Sloetjes, J. W., & Schipper, D. J. (2004). The transition of mild to severe wear of ceramics. Wear, 256(6), 585-591. doi:10.1016/j.wear.2003.10.025Wang, S. W., Chen, L. D., Hirai, T., & Kang, Y. S. (1999). Journal of Materials Science Letters, 18(14), 1119-1121. doi:10.1023/a:1006684631127Muñoz, S., & Anselmi-Tamburini, U. (2012). Parametric investigation of temperature distribution in field activated sintering apparatus. The International Journal of Advanced Manufacturing Technology, 65(1-4), 127-140. doi:10.1007/s00170-012-4155-7Xiong, Y., Fu, Z. Y., Wang, H., Wang, Y. C., & Zhang, Q. J. (2005). Microstructure and IR transmittance of spark plasma sintering translucent AlN ceramics with CaF2 additive. Materials Science and Engineering: B, 123(1), 57-62. doi:10.1016/j.mseb.2005.06.02

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Quantum gravity phenomenology at the dawn of the multi-messenger era—A review

The exploration of the universe has recently entered a new era thanks to the multi-messenger paradigm, characterized by a continuous increase in the quantity and quality of experimental data that is obtained by the detection of the various cosmic messengers (photons, neutrinos, cosmic rays and gravitational waves) from numerous origins. They give us information about their sources in the universe and the properties of the intergalactic medium. Moreover, multi-messenger astronomy opens up the possibility to search for phenomenological signatures of quantum gravity. On the one hand, the most energetic events allow us to test our physical theories at energy regimes which are not directly accessible in accelerators; on the other hand, tiny effects in the propagation of very high energy particles could be amplified by cosmological distances. After decades of merely theoretical investigations, the possibility of obtaining phenomenological indications of Planck-scale effects is a revolutionary step in the quest for a quantum theory of gravity, but it requires cooperation between different communities of physicists (both theoretical and experimental). This review, prepared within the COST Action CA18108 “Quantum gravity phenomenology in the multi-messenger approach”, is aimed at promoting this cooperation by giving a state-of-the art account of the interdisciplinary expertise that is needed in the effective search of quantum gravity footprints in the production, propagation and detection of cosmic messengers.publishedVersio

Global surveillance of cancer survival 1995-2009: analysis of individual data for 25,676,887 patients from 279 population-based registries in 67 countries (CONCORD-2)

BACKGROUND: Worldwide data for cancer survival are scarce. We aimed to initiate worldwide surveillance of cancer survival by central analysis of population-based registry data, as a metric of the effectiveness of health systems, and to inform global policy on cancer control. METHODS: Individual tumour records were submitted by 279 population-based cancer registries in 67 countries for 25·7 million adults (age 15-99 years) and 75,000 children (age 0-14 years) diagnosed with cancer during 1995-2009 and followed up to Dec 31, 2009, or later. We looked at cancers of the stomach, colon, rectum, liver, lung, breast (women), cervix, ovary, and prostate in adults, and adult and childhood leukaemia. Standardised quality control procedures were applied; errors were corrected by the registry concerned. We estimated 5-year net survival, adjusted for background mortality in every country or region by age (single year), sex, and calendar year, and by race or ethnic origin in some countries. Estimates were age-standardised with the International Cancer Survival Standard weights. FINDINGS: 5-year survival from colon, rectal, and breast cancers has increased steadily in most developed countries. For patients diagnosed during 2005-09, survival for colon and rectal cancer reached 60% or more in 22 countries around the world; for breast cancer, 5-year survival rose to 85% or higher in 17 countries worldwide. Liver and lung cancer remain lethal in all nations: for both cancers, 5-year survival is below 20% everywhere in Europe, in the range 15-19% in North America, and as low as 7-9% in Mongolia and Thailand. Striking rises in 5-year survival from prostate cancer have occurred in many countries: survival rose by 10-20% between 1995-99 and 2005-09 in 22 countries in South America, Asia, and Europe, but survival still varies widely around the world, from less than 60% in Bulgaria and Thailand to 95% or more in Brazil, Puerto Rico, and the USA. For cervical cancer, national estimates of 5-year survival range from less than 50% to more than 70%; regional variations are much wider, and improvements between 1995-99 and 2005-09 have generally been slight. For women diagnosed with ovarian cancer in 2005-09, 5-year survival was 40% or higher only in Ecuador, the USA, and 17 countries in Asia and Europe. 5-year survival for stomach cancer in 2005-09 was high (54-58%) in Japan and South Korea, compared with less than 40% in other countries. By contrast, 5-year survival from adult leukaemia in Japan and South Korea (18-23%) is lower than in most other countries. 5-year survival from childhood acute lymphoblastic leukaemia is less than 60% in several countries, but as high as 90% in Canada and four European countries, which suggests major deficiencies in the management of a largely curable disease. INTERPRETATION: International comparison of survival trends reveals very wide differences that are likely to be attributable to differences in access to early diagnosis and optimum treatment. Continuous worldwide surveillance of cancer survival should become an indispensable source of information for cancer patients and researchers and a stimulus for politicians to improve health policy and health-care systems

Search for leptophobic Z ' bosons decaying into four-lepton final states in proton-proton collisions at root s=8 TeV

Peer reviewe