The legacy of Corrado Gini in population studies

This volume contains 12 papers that range over many different research subjects, taking in many of the population questions that, directly or indirectly, absorbed Corrado Gini as demographer and social scientist over several decades. They vary from the analysis of the living conditions and behaviours of the growing foreign population (measurements and methods of analysis, socio-economic conditions and health, ethnic residential segregation, sex-ratio at birth), to studies on the homogamy of couples; from population theories (with reference to the cyclical theory of populations) to the modelling approach to estimating mortality in adult ages or estimating time transfers, by age and sex, related to informal child care and adult care; from historical studies that take up themes dear to Gini (such as the estimates of Italian military deaths in WWI), to the application of Gini’s classical measurements to studying significant phenomena today (transition to adulthood and leaving the parental home, health care, disabled persons and social integration). The subjects and measurements that appear here are not intended to exhaust the broad spectrum of Gini’s research work in the demographic and social field (nor could they), but they can make up a part of the intersection between his vast legacy and some interesting topics in current research, some of which were not even imaginable in the mid twentieth century. Looking at the many contributions that celebrated Gini in Treviso and thinking about his legacy, it seems possible to identify at least two typologies of approach, to be found in this issue of the journal, too. On the one hand, there are contributions that aim to retrieve and discuss themes, methodologies and measurements dealt with or used by Gini so as to evaluate their present relevance and importance in the current scholarly debate. On the other, there are contributions that deal with topics that are far from Gini’s work, as they study very recent phenomena, but actually, among other things, make use of methods and indicators devised by Gini that are now so much part of the common currency of methodology, so they don’t require explicit reference to their Author

Search for galactic axions with a high-Q dielectric cavity

A haloscope of the QUAX--$a\gamma$ experiment, composed of an high-Q resonant cavity immersed in a 8 T magnet and cooled to $\sim 4.5$~K is operated to search for galactic axion with mass $m_a\simeq42.8~\mu\text{eV}$. The design of the cavity with hollow dielectric cylinders concentrically inserted in a OFHC Cu cavity, allowed us to maintain a loaded quality-factor Q $\sim 300000$ during the measurements in presence of magnetic field. Through the cavity tuning mechanism it was possible to modulate the resonance frequency of the haloscope in the region $10.35337-10.35345$~GHz and thus acquire different dataset at different resonance frequencies. Acquiring each dataset for about 50 minutes, combining them and correcting for the axion's signal estimation-efficiency we set a limit on the axion-photon coupling $g_{a\gamma\gamma}< 0.731\times10^{-13}$ GeV$^{-1}$ with the confidence level set at $90\%$

High quality factor photonic cavity for dark matter axion searches

Searches for dark matter axion involve the use of microwave resonant cavities operating in a strong magnetic field. Detector sensitivity is directly related to the cavity quality factor, which is limited, however, by the presence of the external magnetic field. In this paper we present a cavity of novel design whose quality factor is not affected by a magnetic field. It is based on a photonic structure by the use of sapphire rods. The quality factor at cryogenic temperature is in excess of $5 \times 10^5$ for a selected mode.Comment: 6 pages, 7 figure

Coherent Quantum Network of Superconducting Qubits as a Highly Sensitive Detector of Microwave Photons for Searching of Galactic Axions

We propose a novel approach to detect a low power microwave signal with a frequency of the order of several GHz based on a coherent collective response of quantum states occurring in a superconducting qubits network (SQN). An SQN composes of a large number of superconducting qubits embedded in a low-dissipative superconducting resonator. Our theory predicts that an SQN interacting with the off-resonance microwave radiation, demonstrates the collective alternating current Stark effect that can be measured even in the limit of single photon counting. A design of the layout of three terminals SQN detectors containing 10 flux qubits weakly coupled to a low-dissipative R-resonator and T-transmission line was developed. The samples were fabricated by Al-based technology with Nb resonator. The SQN detector was tested in terms of microwave measurements of scattering parameters and two-tone spectroscopy. A substantial shift of the frequency position of the transmission coefficient drop induced by a second tone pump signal was observed, and this effect clearly manifests a nonlinear multiphoton interaction between the second-tone microwave pump signal and an array of qubits

Galactic axions search with a superconducting resonant cavity

To account for the dark matter content in our Universe, post-inflationary scenarios predict for the QCD axion a mass in the range (10-10^3)\,\mu\mbox{eV}. Searches with haloscope experiments in this mass range require the monitoring of resonant cavity modes with frequency above 5\,GHz, where several experimental limitations occur due to linear amplifiers, small volumes, and low quality factors of Cu resonant cavities. In this paper we deal with the last issue, presenting the result of a search for galactic axions using a haloscope based on a 36\,\mbox{cm}^3 NbTi superconducting cavity. The cavity worked at T=4\,\mbox{K} in a 2\,T magnetic field and exhibited a quality factor $Q_0= 4.5\times10^5$ for the TM010 mode at 9\,GHz. With such values of $Q$ the axion signal is significantly increased with respect to copper cavity haloscopes. Operating this setup we set the limit g_{a\gamma\gamma}<1.03\times10^{-12}\,\mbox{GeV}^{-1} on the axion photon coupling for a mass of about 37\,$\mu$eV. A comprehensive study of the NbTi cavity at different magnetic fields, temperatures, and frequencies is also presented

KLASH Conceptual Design Report

The axion, a pseudoscalar particle originally introduced by Peccei, Quinn [1, 2], Weinberg [3], and Wilczek [4] to solve the "strong CP problem", is a well motivated dark-matter (DM) candidate with a mass lying in a broad range from peV to few meV [5]. The last decade witnessed an increasing interest in axions and axion-like particles with many theoretical works published and many new experimental proposals [6] that started a real race towards their discovery. Driven by this new challenge and stimulated by the availability, at the Laboratori Nazionali di Frascati (LNF), of large superconducting magnets previously used for particle detectors [7, 8] at the DAFNE collider, we proposed to build a large haloscope [9] to observe galactic axions in the mass window between 0.2 and 1 µeV [10]. This paper is the Conceptual Design Report (CDR) of the KLASH (KLoe magnet for Axion SearcH) experiment, designed having in mind the performance and dimensions of the KLOE magnet, a large volume superconducting magnet with a moderate magnetic field of 0.6 T. In the first part of this Report we discuss the physics case of KLASH, the theoretical motivation for an axion in the mass window 0.1÷1µeV based on a review of standard and non-standard axion-cosmology (Sec. 1), and the physics reach of the KLASH experiment (Sec. 2), including both the sensitivity to QCD axions and to Dark-Photon DM. The sensitivity plots are based on the detector performance discussed in the second part of the CDR. Here, we summarize the results obtained with calculations and simulations of several aspects of the experiment: the mechanical construction of cryostat and cavity based on the study commissioned to the mechanical engineers of the Fantini-Sud company [11] (Sec. 3); the cryogenics plant (Sec. 4); the RF cavity design and tuning based on detailed simulations with code Ansys-HFSS (Sec. 5); the signal amplification, in particular the first stage based on a Microstrip SQUID Amplifier (Sec. 6). Finally, in Sec. 7, mainly based on the experience of existing experiments [12–14], we discuss the data taking, analysis procedure and computing requirements. The main conclusion we draw from this report is the possibility to build and put in operation at LNF in 2-3 years a large haloscope with the sensitivity to KSVZ axions in the low mass range between 0.2 and 1µeV in a region complementary to that of other experiments with a cost of about 3 MAC. Timeline and cost are competitive with respect to other proposals in the same mass region [15, 16] thanks to the availability of most of the infrastructure, in particular the superconducting magnet and the cryogenics plant. During the writing of this CDR, in July 2019, we were informed about the decision of INFN management to devote the KLOE magnet to the DUNE experiment at Fermilab. The KLOE magnet has always been the preferred choice for several reasons: it was in operation until 2018; its mechanical structure is able to support the several-tons weight of the cryostat and cavity; it is placed in the KLOE assembly-hall that can be used as the experimental area of KLASH. However, another option is given by the FINUDA magnet. The are few aspects to be explored (mechanical strength, move to experimental area, put in operation after more than 10 years), but it has a higher nominal field of 1.1 T in a large volume with an inner radius 1385 mm and length 3800 mm. A preliminary estimate of sensitivity to axions of FLASH, the haloscope built with the FINUDA magnet, gives results similar to those obtained for KLASH. This option will be eventually investigated in another document

Stepping closer to pulsed single microwave photon detectors for axions search

Axions detection requires the ultimate sensitivity down to the single photon limit. In the microwave region this corresponds to energies in the yJ range. This extreme sensitivity has to be combined with an extremely low dark count rate, since the probability of axions conversion into microwave photons is supposed to be very low. To face this complicated task, we followed two promising approaches that both rely on the use of superconducting devices based on the Josephson effect. The first one is to use a single Josephson junction (JJ) as a switching detector (i.e. exploiting the superconducting to normal state transition in presence of microwave photons). We designed a device composed of a coplanar waveguide terminated on a current biased Josephson junction. We tested its efficiency to pulsed (pulse duration 10 ns) microwave signals, since this configuration is closer to an actual axions search experiment. We show how our device is able to reach detection capability of the order of 10 photons with frequency 8 GHz. The second approach is based on an intrinsically quantum device formed by two resonators coupled only via a superconducting qubit network (SQN). This approach relies on quantum nondemolition measurements of the resonator photons. We show that injecting RF power into the resonator, the frequency position of the resonant drop in the transmission coefficient (S21) can be modulated up to 4 MHz. We anticipate that, once optimized, both the devices have the potential to reach single photon sensitivity

Bimodal Approach for Noise Figures of Merit Evaluation in Quantum-Limited Josephson Traveling Wave Parametric Amplifiers

The advent of ultra-low noise microwave amplifiers revolutionized several research fields demanding quantum-limited technologies. Exploiting a theoretical bimodal description of a linear phase-preserving amplifier, in this contribution we analyze some of the intrinsic properties of a model architecture (i.e., an rf-SQUID based Josephson Traveling Wave Parametric Amplifier) in terms of amplification and noise generation for key case study input states (Fock and coherents). Furthermore, we present an analysis of the output signals generated by the parametric amplification mechanism when thermal noise fluctuations feed the device.Comment: 5 pages, 6 figure

Progress in the development of a KITWPA for the DARTWARS project

DARTWARS (Detector Array Readout with Traveling Wave AmplifieRS) is a three years project that aims to develop high-performing innovative Traveling Wave Parametric Amplifiers (TWPAs) for low temperature detectors and qubit readout (C-band). The practical development follows two different promising approaches, one based on the Josephson junctions (TWJPA) and the other one based on the kinetic inductance of a high-resistivity superconductor (KITWPA). This paper presents the advancements made by the DARTWARS collaboration to produce a first working prototype of a KITWPA.Comment: 3 pages, 4 figures. Proceeding of Pisa15th Meeting conferenc