[en] Kaon decay studies seeking new-physics (N P) effects in leptonic (K₁₂) or semileptonic (K₁₃) decays are discussed. A unitarity test of the first row of the CKM mixing matrix is obtained from the Kloe precision measurements of K₁₃ widths for K^±, K_L, and (unique at Kloe) K_S, complemented with the absolute branching ratio for the K_μ2 decay. Kloe results lead to constraint for N P models and can probe possible charged Higgs exchange contribution in S M extensions with two Higgs doublets. The main focus in the present document is set on new measurements of R_K = Γ (K_e2/Γ K_μ2) with an accuracy at the % level, aiming at finding evidence of deviations from the S M prediction induced by lepton-flavor violation N P effects.

[en] The data collected up to a centre-of-mass energy of 202 GeV by the LEP experiments, corresponding to an integrated luminosity of about 0.7 fb^-1, are analysed in search for the scalar partners of quarks and leptons predicted by supersymmetric models. No evidence for any such particles was found. Lower mass limits have been obtained in the framework of the Minimal Supersymmetric Standard Model. (author)

[en] Highlights: •Organic Flash Regenerative Cycles were introduced (OFRCs). •A technical and economic comparison with traditional Organic Flash Cycle (OFCs) was carried out. •Different organic fluids were analyzed. •Results show that specific costs of OFRCs are lower than OFCs. •OFRCs can be a valid alternative to ORCs for low temperature heat recovery. -- Abstract: Organic Flash Cycles (OFCs) can improve the overall efficiency of waste heat recovery or geothermal systems due to a better match of the hot and cold heat transfer curves. However, the lower mean temperature difference between the heat transfer curves implies larger exchanger areas and therefore higher heat exchanger costs. In order to reduce the exchanger size, a new cycle configuration is introduced in this paper, consisting in a new type of organic flash regenerative cycle (OFRC) for heat source temperatures in the range 80–170 °C. The regeneration allows to recover part of the enthalpy of the liquid phase from the flash evaporator increasing the temperature of the liquid at the exchanger inlet, thus reducing the exchanger size. The thermodynamic performance of OFRCs are practically the same as of the OFC, but the unit cost of the system per kW installed power can be 20% lower. A variety of working fluids was tested and results have shown that long molecular chain alkanes provide the best thermodynamic efficiency, but those fluids have the main drawback of a low vapor density, resulting in very large expansion devices and condensers. R601a is the working fluid featuring the best tradeoff between thermodynamic efficiency and components size in the heat source temperature range between 80 °C and 170 °C. The comparison of the OFRC with conventional ORCs has shown the thermodynamic superiority of the OFRC with every tested fluid. Finally the cost analysis has highlighted that OFRCs specific cost has the same magnitude as ORCs for mini and micro scale plants.

[en] Highlights: • A small scale solar ORC was investigated during a year-long simulation. • The system was operated without a thermal storage. • High flexibility thanks to a sliding-velocity control and volumetric expander. • Influence of ORC and solar field parameters considered. • Strong influence of concentration factor and system inertia. - Abstract: In this paper the dynamic behavior of a small low-concentration solar plant with static Compound Parabolic Collectors (CPC) and an ORC power unit with rotary volumetric expander has been analyzed. The plant has been simulated in transient conditions for a year-long operation and for three different sites respectively located in northern, central and southern Italy, in order to evaluate the influence of the latitude on the production. Hourly discretized data for solar radiation and for ambient temperature have been used. The adoption of a sliding-velocity control strategy, has allowed to operate without any storage system with a solar multiple (S.M.) of 1, reducing the amplitude of the solar field and simplifying the control system. Different collectors tilt angles and concentration factors, as well as thermodynamic parameters of the cycle have been tested, to evaluate the optimal working conditions for each locality. Results highlighted that specific production increased with the concentration ratio, and with the decrease of latitude. The comparison with the steady-state analysis showed that this type of control strategy is suited for those configurations having a smaller number of collectors, since the thermal inertia of the solar field is not recovered at all during the plant shut-down phase.

[en] Highlights: • We made a CFD simulation with a validated model. • We analyzed the influence of the geometrical parameters of the collector. • We established a correspondence between the Nusselt number and the characteristic dimensions and parameters of the collector. - Abstract: In this paper a methodology is proposed to estimate thermal heat losses inside compound parabolic collectors (CPC) to be used in designing and validating new collectors' concepts and materials. CFD simulations were carried out on different CPCs, taking into account the effective working conditions and the presence of radiative heat transfer as well as the absence of adiabatic walls. The CFD model was validated considering a previous work reported in literature. The results were employed to develop some correlations by interpolation of numerical data, to express the Nusselt number on the receiver. We used these correlations to calculate heat losses of the receiver and to show the influence of different parameters such as the shape of receiver itself, tilt angle and concentration ratio. The variation of terms of the correlation as a function of characteristic length and concentration was studied. These results might be employed for a preliminary estimation procedure of a CPC collector efficiency and to propose sizing criteria of general validity for this class of devices.

[en] The high resolution electromagnetic calorimeter design and structure are described. The authors point out the keys to obtain excellent performances of the lead-scintillating fibre sampling calorimeter. The test results of three prototypes of the electromagnetic calorimeter, including two small prototypes (one for the barrel and one for the end-cap region) and one full sizew module, are given

[en] Using a large sample of pure, slow, short lived neutral kaon mesons collected with KLOE at DAFNE, we have measured the K_S lifetime. From a fit to the proper time distribution we find τ_S=89.562±0.052 ps, in good agreement with recent measurements. While measuring the ratio R_K=Γ(K_e2(γ)^±)/Γ(K_μ2(γ)^±), the KLOE Collaboration has studied the radiative process K_e2γ. The observed radiation spectrum agrees with predictions from chiral perturbation theory. This result reduces the contribution to systematic uncertainties on measurements of R_K.

[en] Published in summary form only

[en] The Authors review the possibility of formation for a bound state made out of a stop quark and its antiparticle. The detection of a signal from its decay has been investigated for the case of a e⁺e^- collider

[en] In the last decades, the energy market increased its interest towards the smart grids and electrically isolated systems. These systems utilize small size power generators in which volumetric expanders may be employed for a wide range of operative conditions, because of their robustness and reliability.

abspara0015^>In this work a study on a volumetric expander based on the Wankel mechanism was carried out. The aim of this study was to develop a lumped parameters numerical model able to predict the brake effective torque and working fluid consumption of the expander. This model was validated by comparison with experimental results obtained using steam as working fluid. This model allowed to trace the trends of mechanical and thermal losses versus rotating speed and inlet pressure. The experimental results encouraged the need for a further development of this expander, and showed the capability of the numerical model to predict the effective performances of the device.