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Seismic isolation (SI) advantages for new buildings are well known: not only it allows to avoid damage of both structural and non structural elements under strong earthquake, but it mantains building functionality as well. This is possible thanks to strong reduction of accelerations and interstorey drift in the superstructure, i.e. the part of structure above the isolation layer. SI offers additional advantages for seismic retrofit of existing buildings. The main advantage is that the works can be limited at one floor (usually the basement, plus the foundation), without any strenghtening on the superstructure. Consequently, the building can be used during the retrofit works. The safety of the retrofitted building increases significantly. Reaching exactly the same safety level of a new building in the same site would be possible, but it would need some strenghtening in the superstructure, and thus is usually avoided in order to keep the building in function during the works. It is worth noting that for the seismic isolation system, the safety is the same than for a new building. The paper presents in detail three case studies of framed r.c. buildings built in the 1980s and now under retrofit with seismic isolation, that could be representative of many other buildings. During 2009 L'Aquila earthquake, those residential buildings were only slightly damaged, and immediately repaired but without any improvement of their seismic performance. Now the retrofit design is carried out for an earthquake stronger than the 2009 earthquake. Despite the buildings are in the same area (ag=0.261g for the Life Safety Limit State earthquake; ag=0.334g for the Collapse Limit State earthquake, used to design the seismic isolation system), the design spectrum is different because of different type of soil. The isolators are inserted in the basement or in the ground floor that host the garages, thus without affecting the apartments. The safety level reached in the three buildings was higher than 70% of that of new buildings in the same site, while before retrofit it was lower than 16%

The seismic response of base-isolated structures is notably influenced by mechanical properties of isolation devices due to their essential role in structural behavior. Consequently, the variability of such properties should be accounted for in the design process. The current seismic codes prescribe a simplified approach based on structural analyses in two extreme situations resulting from the upper and lower bound design properties of bearings (upper and lower bound analyses). In the case that experimental data are not provided by manufacturers, seismic codes provide the so-called “property modification factors” or “λ-factors”, i.e., modification coefficients to be applied to the nominal dynamic properties of bearings to obtain their upper or lower design properties. The aim of this paper is to provide a historical review of values provided for such factors by the main seismic codes by highlighting the limits, as well as some clerical errors, present in some codes. In particular, the European seismic codes are illustrated in detail, i.e., the Eurocode for bridges (EN 1998-2) and product standard on anti-seismic devices (EN 15129). Both these codes account for different sources of variability, such as the bearings production and the environmental and behavioral effects. For all these effects, the same λ-factor values are provided by the two codes, deriving from the second version of the AASHTO guide specifications for seismic isolation of bridges (AASHTO 1999), which are based on limited and/or old data, especially for high damping rubber bearings (HDRBs), and were never updated in the successive versions. More recent standards are also illustrated, providing different perspectives that deserve attention, even though they require further investigations to be applied in the design practice.

The Italian institute for nuclear physics (INFN) has financed the SIMP project (2019-2021) in order to strengthen its skills and technologies in the field of meV detectors with the ultimate aim of developing a single microwave photon detector. This goal will be pursued by improving the sensitivity and the dark count rate of two types of photodetectors: current biased Josephson Junction (JJ) for the frequency range 10-50 GHz and Transition Edge Sensor (TES) for the frequency range 30-100 GHz. Preliminary results on materials and devices characterization are presented., Comment: 7 pages, 4 figures

This manuscript is on the design and development of a single microwave photon counter based on a current-biased Josephson junction aimed at the detection of light axion dark matter. Simulations and measurements of a Josephson junction are presented. We observe the junction in a quantum tunneling regime, with subsequent dissipation on an external RC circuit.

This study aims to evaluate the performance of a steel storage pallet racking system equipped with a novel seismic isolation system, which is effective along the cross-aisle direction alone. The isolation system consists of two IsolGOODS® isolators, which are curved surface slider bearings as framed into the European Standards for anti-seismic devices. The efficiency of the proposed device in reducing the seismic effects on pallet racks is investigated. Firstly, uniaxial real-time shake table tests are performed, showing a great reduction of floor accelerations. With the help of a herein validated numerical model, advanced knowledge is obtained. Six accelerograms, two normal-fault records, two pulse-like, and two spectrum-compatible series are selected for drawing generally valid statements. As proposed in this work, the outcomes confirm that the isolation system provides substantial reduction in terms of floor accelerations. In contrast, no up-lift of the base-connections is recorded: the uprights are always engaged in compression. On the whole, the most severe condition comes from the pulse-like record (Emilia 2012), in which displacement demand must be carefully considered while defining the isolators to be put in place.

Background suppression plays a crucial role in particle physics experiments searching for rare events, such as neutrinoless double beta decay and dark matter interactions. Bolometers, that are among the most competitive devices in this field, would largely benefit from the development of ultrasensitive light detectors, as the combined readout of the bolometric and light signals enables the particle identification. The CALDER collaboration is developing superconducting light detectors that will match the requirements of next generation experiments: noise lower than 20 eV, large active area (>20 cm 2 ), wide temperature range of operation, high radiopurity, and ease in fabricating hundreds of channels. For this purpose, we are exploiting the excellent energy resolution and the natural multiplexed readout provided by kinetic inductance detectors (KIDs). KIDs have already demonstrated their potentiality as direct detectors of photons for different astrophysical applications. The aim of our project is to apply this technology in particle physics, using indirect detection. These devices can be operated in a phonon-mediated approach, in which KIDs are coupled to a large insulating substrates in order to increase the active surface from a few mm2 to 25 cm 2 . We have already demonstrated the feasibility of a phonon-mediated KIDs-based light detectors, using aluminium sensors. These device reached a baseline sensitivity of around 80 eV with an overall efficiency of about 20%. Currently, we are testing new materials (e.g., Ti-Al and nonstoichiometric TiN) to enhance the sensitivity and reach the goal of our project. We present our results and the physical interpretation of the device behavior. Finally, we also discuss the impact of this project on the most advanced bolometric experiments searching for neutrinoless double beta decay and dark matter.

International audience; We describe the in-flight performance of the horn-coupled lumped element kinetic inductance detector arrays of the balloon-borne OLIMPO experiment. These arrays have been designed to match the spectral bands of OLIMPO: 150, 250, 350, and $460\,\hbox {GHz}$, and they have been operated at $0.3\,\hbox {K}$ and at an altitude of ${37.8}\,\hbox {km}$ during the stratospheric flight of the OLIMPO payload, in Summer 2018. During the first hours of flight, we tuned the detectors and verified their large dynamics under the radiative background variations due to elevation increase of the telescope and to the insertion of the plug-in room-temperature differential Fourier transform spectrometer into the optical chain. We have found that the detector noise equivalent powers are close to be photon noise limited and lower than those measured on the ground. Moreover, the data contamination due to primary cosmic rays hitting the arrays is less than 3% for all the pixels of all the arrays and less than 1% for most of the pixels. These results can be considered the first step of KID technology validation in a representative space environment.

Josephson junctions, in appropriate configurations, can be excellent candidates for detection of single photons in the microwave frequency band. Such possibility has been recently addressed in the framework of galactic axion detection. Here are reported recent developments in the modelling and simulation of dynamic behaviour of a Josephson junction single microwave photon detector. For a Josephson junction to be enough sensitive, small critical currents and operating temperatures of the order of ten of mK are necessary. Thermal and quantum tunnelling out of the zero-voltage state can also mask the detection process. Axion detection would require dark count rates in the order of 0.001 Hz. It is, therefore, is of paramount importance to identify proper device fabrication parameters and junction operation point., Comment: 7 pages, 9 figures

Kinetic Inductance Detectors (KIDs) are superconductive low$-$temperature detectors useful for astrophysics and particle physics. We have developed arrays of lumped elements KIDs (LEKIDs) sensitive to microwave photons, optimized for the four horn-coupled focal planes of the OLIMPO balloon-borne telescope, working in the spectral bands centered at 150 GHz, 250 GHz, 350 GHz, and 460 GHz. This is aimed at measuring the spectrum of the Sunyaev-Zel'dovich effect for a number of galaxy clusters, and will validate LEKIDs technology in a space-like environment. Our detectors are optimized for an intermediate background level, due to the presence of residual atmosphere and room--temperature optical system and they operate at a temperature of 0.3 K. The LEKID planar superconducting circuits are designed to resonate between 100 and 600 MHz, and to match the impedance of the feeding waveguides; the measured quality factors of the resonators are in the $10^{4}-10^{5}$ range, and they have been tuned to obtain the needed dynamic range. The readout electronics is composed of a $cold$ $part$, which includes a low noise amplifier, a dc$-$block, coaxial cables, and power attenuators; and a $room-temperature$ $part$, FPGA$-$based, including up and down-conversion microwave components (IQ modulator, IQ demodulator, amplifiers, bias tees, attenuators). In this contribution, we describe the optimization, fabrication, characterization and validation of the OLIMPO detector system., Proceedings of WOLTE13, September 10-13, 2018 Sorrento, Italy

Kinetic Inductance Detectors made of High-TC superconductor YBCO are designed and fabricated, in view as possible application as high sensitivity, low cost and high-manageability terahertz camera for imaging.

The experimental seismic behaviour of an isolation system, made of high damping rubber bearings, under low energy earthquakes is analysed. The seismically isolated building was instrumented by means of an accelerometer network. It was first characterized dynamically using also fifteen seismometers to record ambient vibrations. Then, all the events of the seismic sequence that struck Central Italy from August 2016 to January 2017 were recorded. These allowed evaluating the effects of earthquakes with different energy on the structure. Due to the long distances from the epicentres of these events, the analysis referred to the behaviour for very low shear strains in the rubber. The resonance frequencies of the base isolated building were much higher than those supposed in the design phase, but the filtering effect was still effective. One of the relative displacement history recorded during the strongest event was applied to the same devices used for the type tests at the construction time. The results obtained in terms of isolator stiffness were consistent with the experimental ones.

International audience; We report on the performance of lumped-elements Kinetic Inductance Detector (KID) arrays for mm and sub-mm wavelengths, operated at 0.3 K during the stratospheric flight of the OLIMPO payload, at an altitude of 37.8 km. We find that the detectors can be tuned in-flight, and their performance is robust against radiative background changes due to varying telescope elevation. We also find that the noise equivalent power of the detectors in flight is smaller by a factor of ~ 2, 8, 3.5, 4.5 at 150, 250, 350 and 460 GHz relative to the one measured in the laboratory, and is close to our calculated photon-noise-limited performance. The effect of primary cosmic rays crossing the detector is found to be consistent with the expected ionization energy loss with phonon-mediated energy transfer from the ionization sites to the resonators. In the OLIMPO detector arrays, at float, cosmic ray events affect less than 4% of the detector samplings for all the pixels of all the arrays, and less than 1% of the samplings for most of the pixels. These results are also representative of what one can expect from primary cosmic rays in a satellite mission with similar KIDs and instrument environment.

In the recent years, the experimental investigation on the frictional response of Curved Surface Sliders (CSS) - the European name for pendulum isolators - has been increased and improved, by performing full-scale dynamic testing, using facilities of large capabilities. Experimental data allows a better understanding on the dependence of the frictional properties of the sliding material under different loading conditions and velocities. This paper presents an investigation of the dependence of friction coefficient on these two parameters by analysing experimental results collected from a number of type tests performed at four dynamic testing facilities on full-scale Double Concave Curved Surface Sliders (DCCSS). All isolators are equipped with Ultra-High Molecular Weight Poly-Ethylene (UHMW-PE) sliding material, a material that in past studies was not frequently investigated. Most of said tests were according to the European Standard EN 15129. The tested isolators have different capacity in terms of vertical load (from 1670 kN to 17500 kN) and displacement. The test velocities range from 250 mm/s to 660 mm/s.

We are developing a Lumped Element Kinetic Inductance Detector (LEKID) array able to operate in the W-band (75-110 GHz) in order to perform ground-based Cosmic Microwave Background (CMB) and mm-wave astronomical observations. The W-band is close to optimal in terms of contamination of the CMB from Galactic synchrotron, free-free, and thermal interstellar dust. In this band, the atmosphere has very good transparency, allowing interesting ground-based observations with large (>30 m) telescopes, achieving high angular resolution (, 16th International Workshop on Low Temperature Detectors, Grenoble 20-24 July 2015, Journal of Low Temperature Physics, Accepted

The main aim of the cryogenic wide-area light detectors with excellent resolution project is the development of cryogenic light detectors with large active area (~50 mm × 50 mm) and noise energy resolution smaller than 20-eV RMS. Such detectors will be used to discriminate the background in next generation large-mass bolometric experiments, such as cryogenic underground observatory for rare events. In this paper, we present the fabrication process of the phonon-mediated kinetic inductance detectors (KIDs). In the first part of the project, Al KIDs have been developed. Thin film Al (40 nm) were evaporated on high quality, high resistivity (>10 kΩ·cm) Si(1 0 0) wafers using a high vacuum electron beam evaporator. Detectors were patterned by direct-write Electron Beam Lithography (EBL) using positive tone resist AR-P 669.06. To improve the energy resolution of our detector, superconductors with higher kinetic inductance, such as the substoichiometric titanium nitride (TiNx), were developed. TiNx is deposited with reactive dc magnetron sputtering. Thus, the fabrication process is subtractive and consists of EBL patterning through negative tone resist AR-N 7700 and SF6 etch using a Deep Reactive Ion Etching - Inductively Coupled Plasma. Critical temperature of TiNx samples was measured using the 4-point probe geometry.

We make use of a niobium film to produce a micrometric vacuum-bridge superconducting bolometer responding to THz frequency. The bolometer works anywhere in the temperature range 2-7 K, which can be easily reached in helium bath cryostats or closed-cycle cryocoolers. In this work the bolometer is mounted on a pulse tube refrigerator and operated to measure the equivalent noise power (NEP) and the response to fast (mu s) terahertz pulses. The NEP above 100 Hz equals that measured in a liquid helium cryostat showing that potential drawbacks related to the use of a pulse tube refrigerator (like mechanical and thermal oscillations, electromagnetic interference, noise) are irrelevant. At low frequency, instead, the pulse tube expansion-compression cycles originate lines at 1 Hz and harmonics in the noise spectrum. The bolometer was illuminated with THz single pulses coming either from a Quantum Cascade Laser operating at liquid nitrogen temperature or from a frequency-multiplied electronic oscillator. The response of the bolometer to the single pulses show that the device can track signals with a rise time as fast as about 450 ns.

We designed, fabricated, and characterized four arrays of horn--coupled, lumped element kinetic inductance detectors (LEKIDs), optimized to work in the spectral bands of the balloon-borne OLIMPO experiment. OLIMPO is a 2.6 m aperture telescope, aimed at spectroscopic measurements of the Sunyaev-Zel'dovich (SZ) effect. OLIMPO will also validate the LEKID technology in a representative space environment. The corrected focal plane is filled with diffraction limited horn-coupled KID arrays, with 19, 37, 23, 41 active pixels respectively at 150, 250, 350, and 460$\:$GHz. Here we report on the full electrical and optical characterization performed on these detector arrays before the flight. In a dark laboratory cryostat, we measured the resonator electrical parameters, such as the quality factors and the electrical responsivities, at a base temperature of 300$\:$mK. The measured average resonator $Q$s are 1.7$\times{10^4}$, 7.0$\times{10^4}$, 1.0$\times{10^4}$, and 1.0$\times{10^4}$ for the 150, 250, 350, and 460$\:$GHz arrays, respectively. The average electrical phase responsivities on resonance are 1.4$\:$rad/pW, 1.5$\:$rad/pW, 2.1$\:$rad/pW, and 2.1$\:$rad/pW; the electrical noise equivalent powers are 45$\:\rm{aW/\sqrt{Hz}}$, 160$\:\rm{aW/\sqrt{Hz}}$, 80$\:\rm{aW/\sqrt{Hz}}$, and 140$\:\rm{aW/\sqrt{Hz}}$, at 12 Hz. In the OLIMPO cryostat, we measured the optical properties, such as the noise equivalent temperatures (NET) and the spectral responses. The measured NET$_{\rm RJ}$s are $200\:\mu\rm{K\sqrt{s}}$, $240\:\mu\rm{K\sqrt{s}}$, $240\:\mu\rm{K\sqrt{s}}$, and $\:340\mu\rm{K\sqrt{s}}$, at 12 Hz; under 78, 88, 92, and 90 mK Rayleigh-Jeans blackbody load changes respectively for the 150, 250, 350, and 460 GHz arrays. The spectral responses were characterized with the OLIMPO differential Fourier transform spectrometer (DFTS) up to THz frequencies, with a resolution of 1.8 GHz., Comment: Published on JCAP

Next-generation experiments searching for neutrinoless double-beta decay must be sensitive to a Majorana neutrino mass as low as 10 meV. CUORE, an array of 988 TeO$_2$ bolometers being commissioned at Laboratori Nazionali del Gran Sasso in Italy, features an expected sensitivity of 50-130 meV at 90% C.L, that can be improved by removing the background from $\alpha$ radioactivity. This is possible if, in coincidence with the heat release in a bolometer, the Cherenkov light emitted by the $\beta$ signal is detected. The amount of light detected is so far limited to only 100 eV, requiring low-noise cryogenic light detectors. The CALDER project (Cryogenic wide-Area Light Detectors with Excellent Resolution) aims at developing a small prototype experiment consisting of TeO$_2$ bolometers coupled to new light detectors based on kinetic inductance detectors. The R&D is focused on the light detectors that could be implemented in a next-generation neutrinoless double-beta decay experiment.

The development of sensitive cryogenic light detectors is of primary interest for bolometric experiments searching for rare events like dark matter interactions or neutrino-less double beta decay. Thanks to their good energy resolution and the natural multiplexed read-out, Kinetic Inductance Detectors (KIDs) are particularly suitable for this purpose. To efficiently couple KIDs-based light detectors to the large crystals used by the most advanced bolometric detectors, active surfaces of several cm$^2$ are needed. For this reason, we are developing phonon-mediated detectors. In this paper we present the results obtained with a prototype consisting of four 40 nm thick aluminum resonators patterned on a 2$\times$2 cm$^2$ silicon chip, and calibrated with optical pulses and X-rays. The detector features a noise resolution $\sigma_E=154\pm7$ eV and an (18$\pm$2)$\%$ efficiency., Comment: 5 pages, 5 figures

Qubits based on the magnetic flux degree of freedom require a flux bias, whose stability and precision strongly affect the qubit performance, up to a point of forbidding the qubit operation. Moreover, in the perspective of multiqubit systems, it must be possible to flux-bias each qubit independently, hence avoiding the traditional use of externally generated magnetic fields in favour of on-chip techniques that minimize cross-couplings. The solution discussed in this paper exploits a persistent current, trapped in a superconducting circuit integrated on chip that can be inductively coupled with an individual qubit. The circuit does not make use of resistive elements that can be detrimental for the qubit coherence. The trapping procedure allows to control and change stepwise the amount of stored current; after that, the circuit can be completely disconnected from the external sources. We show in a practical case how this works and how to drive the bias circuit at the required value., 5 figures submitted to Superconductor Science and Technology

We describe a simple and efficient scheme for the readout of a tunable flux qubit, and present preliminary experimental tests for the preparation, manipulation and final readout of the qubit state, performed in incoherent regime at liquid Helium temperature. The tunable flux qubit is realized by a double SQUID with an extra Josephson junction inserted in the large superconducting loop, and the readout is performed by applying a current ramp to the junction and recording the value for which there is a voltage response, depending on the qubit state. This preliminary work indicates the feasibility and efficiency of the scheme., Comment: 10 pages, 5 figures

The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of 5 $$\,\times \,$$ 5 cm $$^{2}$$ and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio). Finally, we present the response of the detector to optical pulses in the energy range of $$0{-}30$$ keV.

This paper describes the SILER (Seismic-Initiated event risk mitigation in LEad-cooled Reactors) Project results obtained so far in the design of the seismic isolation system of two nuclear power plants: the ELSY configuration for the LFR (Lead-Cooled Fast Reactor) design and the MYRRHA configuration for the accelerator-driven systems (ADS). The seismic protection of the nuclear buildings by means of seismic isolation has been chosen in order to minimize changes to the standard design of the civil works and internal components of the Nuclear Power Plant. The work led to the identification of the optimal design solution, in terms of type and location of seismic devices, to achieve compliance to the floor response acceleration spectra in horizontal and vertical direction, with levels of horizontal displacements not exceeding the maximum acceptable values for structural and non-structural elements. The isolators studied in the project are of the type elastomeric, both High Damping Rubber Bearings and Lead Rubber Bearings; moreover the adoption of a fail-safe system to limit the horizontal isolator deformation in case of beyond design earthquakes is studied.

The fabrication process of a dual mass tuning for gyroscope presents many different challenges: the aspect ratio of the sidewalls, the Aspect Ratio Dependent Etch (ARDE) which causes different gaps to be etched in different etching time [1] , the stiction during the release of the free structures, the notching effect that occurs with a dielectric etch stop layer [2] , the thermal contact during the etch process. In this paper are presented different processes and studies of the etching characteristics in order to avoid or minimize these problems.

The use of dissipative bracings in R. C. frames is of particular interest in seismic‐prone European and Mediterranean countries for retrofit of existing buildings designed according to non‐seismic specifications or old seismic codes, without a capacity design approach and therefore lacking ductility. The supplemental damping offered by the dissipative bracings allows the reduction of the ductility demands in R. C. structural members and thus can significantly reduce their damage. However, most of the experimental research carried out in recent years concerns the use of dissipative bracings in steel structures.This paper describes shaking table tests carried out on a one‐bay, two‐storey, full‐scale spatial R. C. frame equipped with two different types of dissipative braces: fluid viscous dampers atop chevron braces, or buckling restrained braces along the diagonal. Tests were also conducted on the same frame without supplemental damping devices. Scope of these tests was the experimental verification of the...

The development of innovative techniques based on shape memory alloy devices (SMADs), for the purpose of seismic protection for cultural heritage structures, began in Italy within the framework of an European Commission-funded project and continued with further studies and applications. These devices exploit a special property of shape memory alloys: their superelasticity—the ability to recover very high deformation without residual strain, associated with a non-linear constitutive behavior, making it possible to keep the force constant in a wide range of displacements. Consequently, SMADs can be used as special ties capable of limiting the forces transmitted between the structural elements that they connect (e.g., a church facade and the roof), at the same time allowing small displacements. Compared with very rigid conventional steel ties, SMADs are able to reduce accelerations and forces, and thus increase the seismic capacity of the structure. This article provides a brief overview about the research and development that led to the world's first applications of SMADs for seismic protection, within the framework of the post-earthquake restoration of the upper basilica of St. Francis in Assisi, Italy. © Taylor & Francis Group, LLC.

The Messina Strait Bridge would be the world's longest suspension bridge, with a design earthquake characterised by a PGA value of 0.58 g and a distance between the ipocenter and the bridge of 15 km. Said critical structure of course would need a suitable restraint system for traffic braking loads, wind and seismic actions. Each type of load requires a specific behaviour of the restraint system, making its design a big challenge.The restraint system comprises special types of fluid viscous dampers, installed both in longitudinal and transverse direction, both at the towers and at the anchorages. In seismic conditions they behave as viscous dampers, to reduce the forces on the structural elements and the movements of the bridge deck. But in service dynamic conditions, e.g. under traffic or wind load, the devices shall behave like shock transmission units, thus preventing the longitudinal and transverse movements of the deck.FIP Industriale cooperated with the selected General Contractor, a consortium lead by Impregilo, in the design of said viscous dampers. This paper describes the main features of said devices.

We report on the development and test of an integrated system composed of a flux qubit and a rapid single- flux quantum ( RSFQ) circuit that allows qubit manipulation. The goal is to demonstrate the feasibility of control electronics integrated on the same chip as the qubit, in view of the application in quantum computation with superconducting devices. RSFQ logic relies on the storage and transmission of magnetic flux quanta and can be profitably used with superconducting qubits because of the speed, scalability, compatibility with the qubit fabrication process and low temperature environment. While standard RSFQ circuitry is well assessed, the application to quantum computing requires a complete rescaling of parameter values, in order to preserve the qubit coherence and reduce the power dissipation. In the system presented in this paper, the qubit role is played by a superconducting loop interrupted by a small dc SQUID, usually called a double SQUID, which behaves as a tunable rf- SQUID. Its energy potential has the shape of a double well, with the barrier between the wells controlled by magnetic flux applied to the inner dc SQUID. Here for the first time we report measurements at a base temperature of 370 mK in which flux control pulses with desired characteristics were supplied by a RSFQ circuit fabricated using non- standard parameters in the same chip as the qubit.

We discuss the performance, of a normal metal hot electron bolometer (NHEB) that we have measured at 0.3 K . We found that the noise equivalent power was limited by the amplifier noise. To improve the NHEB power response and to make it more robust and reliable we propose to substitute the normal metal with heavily doped silicon. The heavily doped silicon behaves like a metal with lower carrier concentration and has a smaller electron–phonon thermal coupling. We have fabricated superconductor-doped silicon-superconductor contacts (S-Sm-S) and we have used them as thermometers and coolers.

We have realized and tested a fast stroboscopic detector for magnetic flux measurements. The key element of our detector is a hysteretic dc superconducting quantum interference device (SQUID). Stroboscopic read-out of the magnetic flux coupled with the SQUID is accomplished by biasing the SQUID with fast current pulses. The shorter these pulses, the more stroboscopic and less invasive the measurement we are performing. In order to reduce the duration of the current pulses, we take advantage of the superconducting-normal transition induced by laser light in thin superconducting films. The interaction of laser light with superconducting thin films has been investigated thoroughly in the past and many applications have been proposed which rely on the fast typical times with which superconductivity is broken and a resistive behavior arises. We have measured a threshold resolution of 6.9mPhi(0) at 4.2 K, and this value corresponds to the thermodynamic limit of the SQUID. The detector has been accurately characterized: An improved and more sensitive version might prove useful for quantum mechanics and quantum computation experiments, for example, in detecting the state of flux qubits.

We have realized a fully integrated chip containing all the different devices (realized with trilayer Nb/AlO x /Nb technology) necessary to perform the MQC measurements. On the chip we have a double rf-SQUID inductively coupled to two different dc-SQUIDs: a standard dc-SQUID amplifier to monitor the state of the rf-SQUID, and an underdamped dc-SQUID, operating as a two-state system, to perform stroboscopic measurements of the rf-SQUID flux states. On this system we have realized a set of measurements to characterize the different devices at temperatures of the order of tens of mK. We have also performed the first measurements with the dc-SQUID amplifier and with the dc-SQUID switch, making stroboscopic measurements on the rf-SQUID.

Small tunnel junctions, two conducting electrodes separated by a thin insulator, can be successfully used for the fabrication of small planar devices operating at the temperature typical of a helium−3 refrigerator. Junctions can be classified on the base of the electrode material. When the top electrode is a normal-metal and the base electrode is a superconductor we have a NIS junction. With this type of small junctions (overlap area smaller than 0.1 μm2 high sensitive thermometry can be performed and, in particular the temperature change of a normal-metal electron gas of a hot electron bolometer (NHEB)1,2 can be detected. When both electrodes are superconducting we have SIS junctions that allow the fabrication of SSETs (Superconducting Single Electron Transistor), a small superconducting island (0.2–0.4μm2), weakly coupled to two superconducting leads (Cooper pair reservoirs) by means of two tunnel barriers. With a SSET one can realize the most sensitive detector of electric charge: it is generally used to measure the charge stored in small conducting islands 3.

A wide ranging R&D Project (ISTECH) on validation and application of the Innovative Antiseismic Techniques (IATs) for the restoration of Cultural Heritage Structures (CUHESs), especially masonry buildings, based on the Shape Memory Alloys (SMAs), has been funded by the European Commission (EC), in the framework of the Environment and Climate RTD Programme. Because Traditional Restoration Techniques (TRTs) have sometimes proved inadequate in avoiding collapses and often too invasive, the use of superelastic SMA Devices (SMADs) has been developed. Theoretical and numerical studies, as well as intensive testing of material specimens, devices, structural models and in situ campaigns, show that SMADs can substantially increase the stability of masonry CUHESs exposed to an earthquake. Different SMAD types have been investigated to fulfil different structural needs and they can be custom designed taking into account each monument's characteristics. The successful results of the research and its exploitation led to important applications in Italy: the S. Giorgio Church Bell-Tower, located at Trignano, S. Martino in Rio, Reggio Emilia, damaged by the 15th October 1996 earthquake, the transept tympana of the S. Francesco Basilica in Assisi and the S. Feliciano Cathedral fa‡ade in Foligno, both heavily damaged by the September 1997 earthquake. In addition, further studies and applications of SMAD technology are foreseen in Italy in the next future, in the framework of Italian and European research projects and proposals.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper describes the rehabilitation of the S. Giorgio Church Bell-Tower (Trignano, Municipality of S. Martino in Rio, Reggio Emilia, Italy), completed in September 1999. This masonry building, seriously damaged by the earthquake of October 15th 1996 which struck the Reggio Emilia and Modena Districts (Italy), was investigated by the authors immediately after the seismic event, as other ancient Cultural Heritage Structures (CUHESs) in the same area. In the past, seismic events have visited substantial destruction that translates into a significant loss of architectural heritage. The most common solution traditionally used to enhance the CUHESs seismic behaviour is the introduction of localized reinforcements, usually Traditional Steel Ties (TSTs), increasing stability and ductility. Anyway, in many cases said reinforcement techniques, often too invasive, proved to be inadequate to prevent collapse. For these reasons, the Bell-Tower intervention applies Innovative Antiseismic Techniques (IATs) by the use of superelastic Shape Memory Alloy (SMA) Devices (SMADs), a technology developed after a large amount of theoretical studies, numerical analyses and test campaigns. The SMADs, which can be considered a powerful tool with respect to the traditional methods, provide acceleration reduction, force limitation and energy dissipation. Furthermore, they are characterized by low invasivity and complete reversibility. When another earthquake occurred on June 18th 2000, with the same epicenter and a comparable Richter Magnitudo, the Bell-Tower, subjected to a new investigation, showed no damage of any type. Thus, the new seismic event has been the best verification of the retrofit intervention.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.