First observation of Bs -> D_{s2}^{*+} X mu nu decays

Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays Bs -> Ds+ X mu nu and Bs -> D0 K+ X mu nu are detected. Two structures are observed in the D0 K+ mass spectrum at masses consistent with the known D^+_{s1}(2536) and $D^{*+}_{s2}(2573) mesons. The measured branching fractions relative to the total Bs semileptonic rate are B(Bs -> D_{s2}^{*+} X mu nu)/B(Bs -> X mu nu)= (3.3\pm 1.0\pm 0.4)%, and B(Bs -> D_{s1}^+ X munu)/B(Bs -> X mu nu)= (5.4\pm 1.2\pm 0.5)%, where the first uncertainty is statistical and the second is systematic. This is the first observation of the D_{s2}^{*+} state in Bs decays; we also measure its mass and width.Comment: 8 pages 2 figures. Published in Physics Letters

Prompt K_short production in pp collisions at sqrt(s)=0.9 TeV

The production of K_short mesons in pp collisions at a centre-of-mass energy of 0.9 TeV is studied with the LHCb detector at the Large Hadron Collider. The luminosity of the analysed sample is determined using a novel technique, involving measurements of the beam currents, sizes and positions, and is found to be 6.8 +/- 1.0 microbarn^-1. The differential prompt K_short production cross-section is measured as a function of the K_short transverse momentum and rapidity in the region 0 < pT < 1.6 GeV/c and 2.5 < y < 4.0. The data are found to be in reasonable agreement with previous measurements and generator expectations.Comment: 6+18 pages, 6 figures, updated author lis

Measurement of sigma (pp -> bbX) at √s=7 TeV in the forward region

Decays of b hadrons into final states containing a D-0 meson and a muon are used to measure the bb; production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. In the pseudorapidity interval 2 < eta < 6 and integrated over all transverse momenta we find that the average cross-section to produce b-flavoured or b-flavoured hadrons is (75.3 +/- 5.4 +/- 13.0) mu b

Evaluation of waste heat recovery technologies for the cement industry

Cement is the world’s most widely used construction material. In 2019, global production amounted to 4086 MT, of which Colombia contributed 12.59 MT. The main component of cement is Clinker and it appears as an intermediate product in the manufacturing process that is produced in a kiln system at sintering temperatures. Such a process exhibits high environmental impacts due to both elevated emissions of Carbon Dioxide and fuel consumption and it is inherently prone to thermal inefficiencies, as heat losses to the surroundings, because of the large flow rates and high temperatures. In this work, the waste heat obtained from the cooling of a high-temperature gas effluent from the rotary kiln in a Colombian cement plant is analysed for its potential use either to dry wet raw material (limestone) or to generate electricity through an ORC. Material, energy and exergy balances for the steady-state were assisted with simulations in Aspen Plus V.10 software. Exergo-economics analysis followed the traditional approach using the net present value (NPV) of the investment as decision criteria. To achieve a holistic view of the waste heat recovery scenario a sensitivity analysis is carried out varying the outlet temperatures of the hot gases for various working fluids in the ORC. Results showed that the best alternative, NPV = 0.37 MUSD at market conditions of electricity and fuel sale price, delivers a maximum of 3.77 MW of electricity with a thermal efficiency of 15.96% and an exergy efficiency of 37.52% using Cyclo-Pentane as working fluid. None of the dryer units attained a positive NPV and were discarded. However, the highest moisture reduction in the solids stream was 5.67% at T = 120∘C. The option of placing a drying unit immediately after an ORC to completely cool down the gases was economically analysed for ORC cases with best NPV, T= 150∘C and T = 180∘C. But no substantial improvement was found over using the ORC alone. The possibility to improve the simple ORC performance is explored through the inclusion of an internal heat exchanger, such recuperated cycle outperforms its simpler configuration in terms of thermal and economic performance delivering 4.1 MW of net work with an NPV = 0.42 MUSD, a rate of return of 15.58% and a payback time of PB = 6.07 years. This is 8.75% more work with 13.51% better economic performance than the simple ORC.The Royal Academy of Engineerin