[en] In view of new modes of operation of the SPS, the old superheterodyne receivers designed for the closed orbit measurements of fixed target beams are being replaced by homodyne 200 MHz receivers with a better time resolution for measuring single bunches. The new receivers have a bandwidth of 4 MHz, a dynamic range of 70dB, and are able to measure the position either of continuous beams with 10¹² to 5x10¹³ppp bunched at 200 MHz CW for fixed target physics, or of single bunches shorter than 5ns with 10⁹ to 2X10¹¹ particles per bunch when the SPS is used as a ppbar collider or as an e⁺e^- injector for LEP. The homodyne receiver has been chosen for its simple layout, linearity, excellent noise immunity and high accuracy of the beam centre position. The built-in calibration facility using the intensity signal of the beam allows to calibrate all 240 receivers and acquisition systems of the closed orbit measurement for zero offset errors to less than 5x10^-3 of the monitor radius and for relative gain errors to less than 4x10^-2. The same synchronous receivers, but running at 20 MHz and 50 MHz, are also used for intensity and lifetime measurements of the SPS collider

[en] A series of record breaking precipitation events have stricken the mountainous area of Emilia-Romagna Region (northern Apennines, Italy) over the last years. As consequence, several geomorphological processes, like widespread debris flows along the slopes and hyperconcentrated flood in the stream channels, shallow landslides and overbank flooding affected the territory, causing serious damages to man-made structures. The detailed study of these recent deposits compared with fossil peat bog and lake paleodeposits can provide useful insight to support a strong match between precipitation intensity and warm climatic phases in antecedent climatic periods, as expected by the increase air water vapour holding capacity at higher temperatures Here we present the results of the field campaign performed in summer 2017 at Lake Moo a 0.15km2 peat bog located at an altitude of 1130m a.s.l. The chosen area has been affected, during the flooding of the upper Trebbia and Nure valleys 13-14 September 2015, by several high-density flows generated by the stream that flow into the plain. Our main assumption is that, in such a small drainage basin (area <2 km2), with favourable geologic and geomorphic characteristics implying advantageous sediment transfer into lake, high density flood can be triggered only by high precipitation intensity events (HPI) lasting a sufficient amount of time for water to infiltrate and mobilize large quantities of debris. The sedimentary succession (ca. 13 m-thick) was studied through the extraction of two cores and one trench. The facies/paleoenvironmental interpretation of the sedimentary succession, characterized by clusters of coarsegrained alluvial deposits interbedded with organic-rich silty clays and peaty layers, was achieved combining sedimentological and pollen data with pedological data and radiocarbon dating (AMS 14C). Observed depositional cycles, retrieved by Lake Moo cores and trench, were put in relation with other specific paleoclimatic proxies available in literature for the North-Apennine area. This comparison illustrate that the increase of extreme paleoflood (associated with coarse-grained deposits similar to the ones observed recently) correlates well with warm phases (at millennial scale) , with a maximum activity in during the holocene thermal maximum. (author)

[en] This paper reports on the CERN SPS superconducting (s.c.) cavity (LEP s.c. cavity prototype), installed to investigate behavior in a real accelerator environment and to obtain some additional voltage for e⁺e^- acceleration when the SPS is working as LEP injector. In the SPS supercycle (14.4 s long) low intensity e⁺e^- beams (0.5 MA DC) and high intensity proton beams are accelerated alternately. During the lepton cycles, the s.c. cavity produces the highest possible voltage for e⁺e^- acceleration (8.5 MV total for the nominal field of 5 MV/m at 352 MHz). On the other hand, during the high intensity proton cycle the cavity impedance must be reduced drastically to avoid beam instabilities. This can be achieved by active beam compensation where the amplifier driven by a feedback system feeds a current into the cavity which just cancels the current of the beam. In this way the cavity voltage can be made negligibly small even in the presence of the strong proton beam current (0.2A DC)

[en] New beam monitors and receivers have been constructed for the position measurements of the colliding panti p beams in the SPS. The directional coupler has been chosen as monitor for its accuracy, directivity and simple construction. Due to the directivity of the coupler, the beam position can be measured separately, for p and anti p beams, even in the zone of interaction. The new superheterodyne 200 MHz receiver and synchronous detector are capable of measuring the beam position of single bunches, shorter than 5 ns at intervals of > 1 μs, as well as continuous beams bunched at 200 MHz CW. The same system can be used both in the transfer lines and in the ring, for single passage or closed orbit measurements of all or individual single bunches. The resolving power of the position measurement amounts to 0.02 mm, as was demonstrated by beam tests. Momentum differences Δp/p >= 5x10^-5 can be detected between different bunches at injection. (Auth.)

[en] Ricerca sul Sistema Energetico S.p.A. (RSE) has been gaining a relevant experience in the simulation, design and installation of resistive-type Superconducting Fault Current Limiter (SFCL) devices for more than five years in the framework of a R and D national project funded by the Ricerca di Sistema (RdS). The most recent outcome of this research activity is the installation of a resistive-type BSCCO-based 9 kV / 3.4 MVA SFCL device in a single feeder branch of the Medium Voltage (MV) distribution network managed by A2A Reti Elettriche S.p.A (A2A) in the Milano area. This installation represents the first SFCL successfully installed in Italy. In this paper, we report on the main outcomes after a more than 1-year long steady-state field testing activity. The design of an upgraded device to be installed in the same substation has already been initiated: the new SFCL will allow to protect four different feeders, therefore implying a device upgrade up to 15.6 MVA.

[en] In the past, bismuth-based high temperature superconductors (HTS) was the only commercially available HTS conductors. The recent achievements in the production of MgB₂ tapes and YBCO coated conductors (CC) persuaded us to study both these HTS as potential candidates for Superconducting Fault Current Limiter (SFCL) applications. In this work, we report on critical current measurements on MgB₂ tapes and windings and YBCO CC at 4.2 K and in the temperature range 65-80 K, respectively. Results of electrical characterizations on MgB₂ and YBCO specimens having different metallic matrix, are used in a numerical model able to predict the SFCL behaviour in view of their potential applications

[en] A world review is presented of the ''leading''-particle effect in hadron physics: baryon-baryon, baryon-antibaryon, meson-baryon and photon-baryon processes are studied and compared with hadron production from an initial state which does not contain any hadron. In this latter case, the ''leading''-particle effect is fully present even in hadron interactions initiated by neutrinos. The importance of the ''leading'' effect in hadron physics is discussed. (author)

[en] By using three different c.m. energies in pp interactions, √s = 30, 44, 62 GeV, it is shown that the average charged-particle multiplicity < nsub(ch)> scales with √s once the correct hadronic energy available for multiparticle production, Esub(had), is used as basic parameter. The pp data, analyzed in this way, are compared with e⁺e^- data at equivalent energies. The agreement is very satisfactory. (author)

[en] The method of removing the leading protons in order to study the properties of multiparticle systems produced in pp interactions is compared, in a direct way, with the standard method. The experimental results show that the remarkable agreement between pp interactions and e⁺e^- annihilations, found by removing the leading protons, is lost if the standard analysis is adopted. This shows the validity and the relevance of our method of subtracting the leading-proton effects in order to understand the properties of multiparticle systems produced in strong interactions. The experiment has been performed using two values of the pp c.m. energy, (√s)sub(pp) = 30 and 62 GeV. (author)

[en] The inclusive transverse-momentum distribution of the multiparticle systems produced in low-psub(T) proton-proton interactions at √s = 30 and 62 GeV has been studied. The analysis was performed removing from the final state the leading proton and redefining the effective hadronic energy available for particle production. Excellent agreement for energies up to 13 GeV is found between (pp) and (e⁺e^-). At higher energy the (pp) data show a less pronounced growth than the (e⁺e^-) data. (author)