Design of a 5th Generation District Heating Substation Prototype for a Real Case Study

The evolution of district heating networks is moving toward low temperatures in heat distribution with so called 4th generation networks. However, the lowest heat transfer fluid temperatures in district heating are achieved through ultra-low temperature networks, referred to as 5th generation district heating networks (5GDHNs). Low temperatures in heat distribution results in an extremely different configuration of 5GDHN compared to traditional district heating network, especially in the grid substation due to the inability to directly couple the grid with the buildings. This paper presents a detailed design of a 5th generation substation prototype, which is carried out to verify the proper operation and monitor the performance of this type of substation in a real case study. The prototype is fed by low-temperature waste heat, currently dissipated through evaporative towers, and will be built in the city of Brescia, Italy. The layout of the substation prototype, consisting of a bidirectional pumping system, a reversible water-to-water heat pump, an inertial thermal energy storage and a heat exchanger, is presented. An analysis is performed to figure out which refrigerant offers the best performance of the heat pump. In addition, fixed the refrigerant, the performance of the grid connected heat pump is found to be increased from 29.5% to 55.5% for both heating and cooling compared with a stand-alone air-to-water heat pump solution. Finally, the process flow diagram and the piping and instrumentation diagram of the substation are presented and commented

Design of a 5th Generation District Heating Substation Prototype for a Real Case Study

The evolution of district heating networks is moving toward low temperatures in heat distribution with so called 4th generation networks. However, the lowest heat transfer fluid temperatures in district heating are achieved through ultra-low temperature networks, referred to as 5th generation district heating networks (5GDHNs). Low temperatures in heat distribution results in an extremely different configuration of 5GDHN compared to traditional district heating network, especially in the grid substation due to the inability to directly couple the grid with the buildings. This paper presents a detailed design of a 5th generation substation prototype, which is carried out to verify the proper operation and monitor the performance of this type of substation in a real case study. The prototype is fed by low-temperature waste heat, currently dissipated through evaporative towers, and will be built in the city of Brescia, Italy. The layout of the substation prototype, consisting of a bidirectional pumping system, a reversible water-to-water heat pump, an inertial thermal energy storage and a heat exchanger, is presented. An analysis is performed to figure out which refrigerant offers the best performance of the heat pump. In addition, fixed the refrigerant, the performance of the grid connected heat pump is found to be increased from 29.5% to 55.5% for both heating and cooling compared with a stand-alone air-to-water heat pump solution. Finally, the process flow diagram and the piping and instrumentation diagram of the substation are presented and commented

Measurement of CPCP-violating and mixing-induced observables in Bs0→ϕγB_s^0 \to \phi\gamma decays

International audienceA time-dependent analysis of the Bs0→ϕγ decay rate is performed to determine the CP -violating observables Sϕγ and Cϕγ and the mixing-induced observable AϕγΔ. The measurement is based on a sample of pp collision data recorded with the LHCb detector, corresponding to an integrated luminosity of 3  fb-1 at center-of-mass energies of 7 and 8 TeV. The measured values are Sϕγ=0.43±0.30±0.11, Cϕγ=0.11±0.29±0.11, and AϕγΔ=-0.67-0.41+0.37±0.17, where the first uncertainty is statistical and the second systematic. This is the first measurement of the observables S and C in radiative Bs0 decays. The results are consistent with the standard model predictions

Measurement of CP violation in the Bs0→ϕϕ {B}_s^0\to \phi \phi decay and search for the B0→ϕϕB^0\rightarrow \phi\phi decay

International audienceA measurement of the time-dependent CP-violating asymmetry in ${B}_s^0\to \phi \phi$ decays is presented. Using a sample of proton-proton collision data corresponding to an integrated luminosity of 5.0 fb^{−}^{1} collected by the LHCb experiment at centre-of-mass energies $\sqrt{s}$ = 7 TeV in 2011, 8 TeV in 2012 and 13 TeV in 2015 and 2016, a signal yield of around 9000 ${B}_s^0\to \phi \phi$ decays is obtained. The CP-violating phase ${\phi}_s^{s\overline{s}s}$ is measured to be −0.073 ± 0.115(stat) ± 0.027(syst) rad, under the assumption it is independent of the helicity of the ϕϕ decay. In addition, the CP-violating phases of the transverse polarisations under the assumption of CP conservation of the longitudinal phase are measured. The helicity-independent direct CP-violation parameter is also measured, and is found to be |λ| = 0.99 ± 0.05(stat) ± 0.01(syst). In addition, T-odd triple-product asymmetries are measured. The results obtained are consistent with the hypothesis of CP conservation in $\overline{b}\to \overline{s}s\overline{s}s$ transitions. Finally, a limit on the branching fraction of the B$^{0}$ → ϕϕ decay is determined to be $\mathcal{B}\left({B}^0\to \phi \phi \right)<2.7\times {10}^{-8}$ at 90 % confidence level

Observation of Several Sources of CPCP Violation in B+→π+π+π−B^+ \to \pi^+ \pi^+ \pi^- Decays

International audienceObservations are reported of different sources of CP violation from an amplitude analysis of B+→π+π+π- decays, based on a data sample corresponding to an integrated luminosity of 3  fb-1 of pp collisions recorded with the LHCb detector. A large CP asymmetry is observed in the decay amplitude involving the tensor f2(1270) resonance, and in addition significant CP violation is found in the π+π-S wave at low invariant mass. The presence of CP violation related to interference between the π+π-S wave and the P wave B+→ρ(770)0π+ amplitude is also established; this causes large local asymmetries but cancels when integrated over the phase space of the decay. The results provide both qualitative and quantitative new insights into CP -violation effects in hadronic B decays

Amplitude analysis of the B+→π+π+π−B^+ \rightarrow \pi^+\pi^+\pi^- decay

International audienceThe results of an amplitude analysis of the charmless three-body decay B+→π+π+π-, in which CP-violation effects are taken into account, are reported. The analysis is based on a data sample corresponding to an integrated luminosity of 3  fb-1 of pp collisions recorded with the LHCb detector. The most challenging aspect of the analysis is the description of the behavior of the π+π-  S-wave contribution, which is achieved by using three complementary approaches based on the isobar model, the K-matrix formalism, and a quasi-model-independent procedure. Additional resonant contributions for all three methods are described using a common isobar model, and include the ρ(770)0, ω(782) and ρ(1450)0 resonances in the π+π- P-wave, the f2(1270) resonance in the π+π- D-wave, and the ρ3(1690)0 resonance in the π+π- F-wave. Significant CP-violation effects are observed in both S- and D-waves, as well as in the interference between the S- and P-waves. The results from all three approaches agree and provide new insight into the dynamics and the origin of CP-violation effects in B+→π+π+π- decays

Search for the lepton-flavour-violating decays Bs0→τ±μ∓B^{0}_{s}\to\tau^{\pm}\mu^{\mp} and B0→τ±μ∓B^{0}\to\tau^{\pm}\mu^{\mp}

International audienceResults are reported from a search for the rare decays Bs0→τ±μ∓ and B0→τ±μ∓, where the τ lepton is reconstructed in the channel τ-→π-π+π-ντ. These processes are effectively forbidden in the standard model, but they can potentially occur at detectable rates in models of new physics that can induce lepton-flavor-violating decays. The search is based on a data sample corresponding to 3  fb-1 of proton-proton collisions recorded by the LHCb experiment in 2011 and 2012. The event yields observed in the signal regions for both processes are consistent with the expected standard model backgrounds. Because of the limited mass resolution arising from the undetected τ neutrino, the Bs0 and B0 signal regions are highly overlapping. Assuming no contribution from B0→τ±μ∓, the upper limit B(Bs0→τ±μ∓)<4.2×10-5 is obtained at 95% confidence level. If no contribution from Bs0→τ±μ∓ is assumed, a limit of B(B0→τ±μ∓)<1.4×10-5 is obtained at 95% confidence level. These results represent the first limit on B(Bs0→τ±μ∓) and the most stringent limit on B(B0→τ±μ∓)

Measurement of the electron reconstruction efficiency at LHCb

International audienceThe single electron track-reconstruction efficiency is determined using a sample corresponding to $1.3~\mathrm{fb}^{-1}$of $pp$ collision data recorded with the LHCb detector in 2017. This measurement exploits $B^+\to J/\psi (e^+e^-)K^+$ decays, where one of the electrons is fully reconstructed and paired with the kaon, while the other electron is reconstructed using only the information of the vertex detector. Despite this partial reconstruction, kinematic and geometric constraints allow the $B^+$-meson mass to be reconstructed and the signal to be well separated from backgrounds. This in turn allows the electron reconstruction efficiency to be measured by matching the partial track segment found in the vertex detector to tracks found by LHCb's regular reconstruction algorithms. The agreement between data and simulation is evaluated, and corrections are derived for simulated electrons in bins of kinematics. The presented method allows LHCb to measure branching fractions involving single electrons with a an electron reconstruction systematic uncertainty below $1\%$

Observation of the Λb0→χc1(3872)pK−\Lambda_b^0\rightarrow \chi_{c1}(3872)pK^- decay

International audienceUsing proton-proton collision data, collected with the LHCb detector and corresponding to 1.0, 2.0 and 1.9 fb$^{−1}$ of integrated luminosity at the centre-of-mass energies of 7, 8, and 13 TeV, respectively, the decay {\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1} (3872)pK$^{−}$ with χ$_{c1}$(3872) → J/ψ π$^{+}$π$^{−}$ is observed for the first time. The significance of the observed signal is in excess of seven standard deviations. It is found that (58 ± 15)% of the decays proceed via the two-body intermediate state χ$_{c1}$(3872)Λ(1520). The branching fraction with respect to that of the ${\Lambda}_{\mathrm{b}}^0$ → ψ(2S)pK$^{−}$ decay mode, where the ψ(2S) meson is reconstructed in the J/ψ π$^{+}$π$^{−}$ final state, is measured to be: $ \frac{\beta \left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1}(3872){\mathrm{pK}}^{-}\right)}{\beta \left({\Lambda}_{\mathrm{b}}^0\to \uppsi \left(2\mathrm{S}\right){\mathrm{pK}}^{-}\right)}\times \frac{\beta \left({\upchi}_{\mathrm{c}1}(3872)\to \mathrm{J}/\uppsi {\uppi}^{+}{\uppi}^{-}\right)}{\beta \left(\uppsi \left(2\mathrm{S}\right)\to \mathrm{J}/\uppsi {\uppi}^{+}{\uppi}^{-}\right)}=\left(5.4\pm 1.1\pm 0.2\right)\times {10}^{-2},