arXiv subjects

S. Tocci

Publications and source records attributed to S. Tocci.

At least 19 recordsLinked to original sources

arXiv2026

Broad frequency tuning of a Nb$_{3}$Sn superconducting microwave cavity for dark matter searches

We demonstrate a novel broad-frequency tuning mechanism for superconducting microwave cavities designed for dark matter searches. Using a Nb$_3$Sn-coated cigar-shaped cavity operating at approximately 9\,GHz, we achieve continuous frequency tuning exceeding 1\,GHz by mechanically separating the two cavity halves: a "tuning-by-opening" technique. Finite-element method simulations predict that radiative losses do not degrade the quality factor even for large openings, as a closed cavity with an intrinsic quality factor of $10^7$ maintains this value for apertures up to 9\,mm, corresponding to a tuning range from 9.0 to 7.5\,GHz. Experimental validation using both copper ring spacers and a continuous sliding mechanism confirms $Q_0$ values exceeding the dark matter quality factor across the entire explored frequency range, despite mechanical imperfections and film non-uniformities. This tuning approach avoids inserting elements into the resonant volume, making it particularly suitable for high-Q superconducting cavities in axion haloscope experiments and readily applicable to REBCO-based implementations capable of operating in multi-tesla magnetic fields.

physics.ins-det↗

arXiv2025

Coherent oscillations in weakly anharmonic NbSe2 qubit

The functionalization of quantum devices to increase their performance and extend their fields of application is an extremely active research area. One of the most promising approaches is to replace aluminum with more performant materials. Within this context, van der Waals (vdW) materials are ideal candidates since they would allow to embed their unique properties into qubits. However, the realization of qubits based on vdW materials other than graphene is yet to be achieved. In this work we present a weakly anharmonic NbSe2 qubit. Our device exhibits a relaxation time T1 = 6.5 +\- 0.4 us which is roughly 2 orders of magnitude larger of other vdW qubits in addition to robustness to photon noise up to 5-10 thermal photons. Our work serves as a demonstrator of the advantage of integration of vdW materials into quantum technologies as well as serving as the first step toward the application of quantum non demolition photon detection protocols in the challenging field of dark matter search.

quant-ph↗

arXiv2024

Transmon qubit modeling and characterization for Dark Matter search

This study presents the design, simulation, and experimental characterization of a superconducting transmon qubit circuit prototype for potential applications in dark matter detection experiments. We describe a planar circuit design featuring two non-interacting transmon qubits, one with fixed frequency and the other flux tunable. Finite-element simulations were employed to extract key Hamiltonian parameters and optimize component geometries. The qubit was fabricated and then characterized at $20$ mK, allowing for a comparison between simulated and measured qubit parameters. Good agreement was found for transition frequencies and anharmonicities (within 1\% and 10\% respectively) while coupling strengths exhibited larger discrepancies (30\%). We discuss potential causes for measured coherence times falling below expectations ($T_1\sim\,$1-2 \textmu s) and propose strategies for future design improvements. Notably, we demonstrate the application of a hybrid 3D-2D simulation approach for energy participation ratio evaluation, yielding a more accurate estimation of dielectric losses. This work represents an important first step in developing planar Quantum Non-Demolition (QND) single-photon counters for dark matter searches, particularly for axion and dark photon detection schemes.

quant-ph↗

arXiv2024

Search for Axion dark matter with the QUAX-LNF tunable haloscope

We report the first experimental results obtained with the new haloscope of the QUAX experiment located at Laboratori Nazionali di Frascati of INFN (LNF). The haloscope is composed of a OFHC Cu resonant cavity cooled down to about 30 mK and immersed in a magnetic field of 8 T. The cavity frequency was varied in a 6 MHz range between 8.831496 and 8.83803 GHz. This corresponds to a previously unprobed mass range between 36.52413 and 36.5511 $\mu$eV. We don't observe any excess in the power spectrum and set limits on the axion-photon coupling in this mass range down to $g_{a\gamma\gamma} < 0.861 \times 10^{-13}$ GeV$^{-1}$ with the confidence level set at $90\%$.

physics.ins-det↗

arXiv2023

Upgrade of the SPARC_LAB LLRF system and recent X-band activities in view of EuPRAXIA@SPARC_LAB project

SPARC_LAB is a high-brightness electron photoinjector dedicated to FEL radiation production and research on novel acceleration techniques. It has been in operation at LNF since 2005. It is composed of a newly designed brazeless 1.6-cell S-band RF gun, two 3 meter long travelling wave S-band accelerating structures, and a 1.4 meter C-band structure that acts as an energy booster. Recently, a plasma interaction chamber was installed to study and optimize beam-driven plasma acceleration schemes. During fall 2023, a major upgrade of the entire low-level RF (LLRF) system will take place to consolidate and improve performance in terms of amplitude, phase resolution, and stability. The original analog S-band and the digital C-band LLRF systems will be replaced by commercial, temperature-stabilized, FPGA-controlled digital LLRF systems manufactured by Instrumentation Technologies. Additionally, the reference generation and distribution will be updated. In parallel with this activity, there is a growing interest in X-band LLRF at LNF due to the EuPRAXIA@SPARC\_LAB project. This project aims to build an FEL user facility driven by an X-band linac at LNF in the coming years. To test X-band RF structures and waveguide components, a high-power X-band test stand named TEX has been installed and recently commissioned. A detailed view of the TEX LLRF system, based on a commercial S-band system with a dedicated up/down-converter stage, will be discussed, along with the limitations of such an approach.

physics.acc-ph↗

arXiv2023

Upgrade of the fast analogue intra-pulse phase feedback at SPARC_LAB

SPARC_LAB is a facility designed for the production of FEL radiation and the exploration of advanced acceleration techniques using a high brightness electron photo-injector. Specifically, particle-driven plasma wakefield acceleration (PWFA) necessitates exceptional beam stability, in order to minimize the jitter between the driver and witness beams. This requirement directly translates into RF phase jitter minimization, since a velocity bunching (RF compression) working point is employed at SPARC_LAB for acceleration. In the past, a fast intra-pulse phase feedback system has been developed to stabilize the klystron RF pulse. This allowed to reach a phase stability of S-band power units (both driven by PFN modulators) below 50 fs rms. However, in order to meet the more stringent requirements of PWFA scheme, some upgrades of this feedback system have been recently carried out. A prototype has been tested on a C-band klystron driven by a solid-state modulator, in order to investigate the possibility for an additional improvement resulting from the inherently more stable power source. In this paper the preliminary measurement results obtained at SPARC_LAB after such upgrades will be reviewed.

physics.acc-ph↗

arXiv2023

TEX (TEst stand for X-band) at LNF

TEX facility if commissioned for high power testing to characterize accelerating structures and validate them for the operation on future particle accelerators for medical, industrial and research applications. At this aim, TEX is directly involved in the LNF leading project EuPRAXIA@SPARC_Lab. The brief description of the facility and its status and prospective will be provided.

physics.acc-ph↗

arXiv2023

Search for galactic axions with a traveling wave parametric amplifier

A traveling wave parametric amplifier has been integrated in the haloscope of the QUAX experiment. A search for dark matter axions has been performed with a high Q dielectric cavity immersed in a 8 T magnetic field and read by a detection chain having a system noise temperature of about 2.1 K at the frequency of 10.353 GHz. Scanning has been conducted by varying the cavity frequency using sapphire rods immersed into the cavity. At multiple operating frequencies, the sensitivity of the instrument was at the level of viable axion models.

hep-ex↗

arXiv2023

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.

quant-ph↗

arXiv2022

Search for galactic axions with a high-Q dielectric cavity

A haloscope of the QUAX--$aγ$ 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 $m_a\simeq42.8~μ\text{eV}$. 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 $g_{aγγ}< 0.731\times10^{-13}$ GeV$^{-1}$ with the confidence level set at $90\%$.

hep-ex↗

arXiv2022

A high-Q microwave dielectric resonator for axion dark matter haloscopes

The frequency band 1-15 GHz provides exciting prospects for resonant axion haloscopes as indicated by cosmological and astrophysical arguments. Among the challenges currently addressed to reach the required sensitivity, the development of high quality factor cavities that tolerate multi-Tesla fields plays a central role. We report a 3D resonator based on a right circular copper cavity with hollow cylinders that confine higher order modes around the cylinder axis. Its effective volume at 10.3\,GHz is $3.4 \cdot 10^{-2}$ liters, and under an 8\,T-field we measured an internal quality factor of more than 9 millions. These parameters demonstrate the potential of this unique resonator to probe galactic dark matter axion at remarkable scan rates of 15\,MHz/day when the cavity is readout by a quantum-limited receiver.

physics.ins-det↗

arXiv2021

Search for invisible axion dark matter of mass m$_a=43~μ$eV with the QUAX--$aγ$ experiment

A haloscope of the QUAX--$aγ$ experiment composed of an oxygen-free high thermal conductivity-Cu cavity inside an 8.1 T magnet and cooled to $\sim200$ mK is put in operation for the search of galactic axion with mass $m_a\simeq43~μ\text{eV}$. The power emitted by the resonant cavity is amplified with a Josephson parametric amplifier whose noise fluctuations are at the standard quantum limit. With the data collected in about 1 h at the cavity frequency $ν_c=10.40176$ GHz, the experiment reaches the sensitivity necessary for the detection of galactic QCD-axion, setting the $90\%$ confidence level limit to the axion-photon coupling $g_{aγγ}<0.639\times10^{-13}$ GeV$^{-1}$.

hep-ex↗

arXiv2020

Realization of a high quality factor resonator with hollow dielectric cylinders for axion searches

The realization and characterization of a high quality factor resonator composed of two hollow-dielectric cylinders with its pseudo-TM$_{030}$ mode resonating at 10.9 GHz frequency is discussed. The quality factor was measured at the temperatures 300 K and 4 K obtaining $\mbox{Q}_{300\mbox{K}}=(150,000\pm 2,000)$ and $\mbox{Q}_{4\mbox{K}}=(720,000\pm 10,000)$respectively, the latter corresponding to a gain of one order of magnitude with respect to a traditional copper cylindrical-cavity with the corresponding TM$_{010}$ mode resonating at the same frequency. The implications to dark-matter axion-searches with cavity experiments are discussed showing that the gain in quality factor is not spoiled by a reduced geometrical coupling $C_{030}$ of the cavity mode to the axion field. This reduction effect is estimated to be at most 20%. Numerical simulations show that frequency tuning of several hundreds MHz is feasible.

physics.ins-det↗

arXiv2020

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.

physics.ins-det↗

arXiv2019

Tunable vortex dynamics in proximity junction arrays: a possible accurate and sensitive 2D THz detector

An array of superconducting proximity islands has been shown to be highly tunable by electric and magnetic fields. Indeed, a small change in the electric and magnetic field can tune the system from a vortex Mott insulator to a vortex metal. This transition from localized to a non-localized state can occur as soon as the density of the superconducting vortices matches the density of the pinning sites in a non defective structure. The possibility of further modulation of non-localized superconducting states via enhancement of the superconducting order parameter or modulation of the Josephson plasma frequency is discussed. Based on the non-bolometric effects associated with the occurrence of non-equilibrium phenomena in this original superconducting networks we discuss also the possible applications of this array for a conceptually new type of radiation detector.

cond-mat.supr-con↗

arXiv2019

KLASH Conceptual Design Report

The last decade witnessed an increasing interest in axions and axion-like particles with many theoretical works published and many new experimental proposals that started a real race towards their discovery. This paper is the Conceptual Design Report of the KLASH (KLoe magnet for Axion SearcH) experiment at the Laboratori Nazionali di Frascati (LNF). The idea of this experiment has been stimulated by the availability of the large volume superconducting magnet, with a moderate magnetic field of 0.6 T, used in the KLOE detector at the DAFNE collider. 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 1 $μ$eV, complementary to that of other experiments. Timeline and cost are competitive with respect to other proposals in the same mass region thanks to the availability of most of the infrastructure, in particular the superconducting magnet and the cryogenics plant.

physics.ins-det↗

arXiv2019

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 $(10-10^3)\,μ\mbox{eV}$. 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 $g_{aγγ}<1.03\times10^{-12}\,\mbox{GeV}^{-1}$ on the axion photon coupling for a mass of about 37\,$μ$eV. A comprehensive study of the NbTi cavity at different magnetic fields, temperatures, and frequencies is also presented.

physics.ins-det↗

arXiv2018

The Klash Proposal: Status and Perspectives

Recently some of the authors proposed a search for galactic axions with mass about 0.2~$μ$eV using a large volume resonant cavity, tens of cubic meters, cooled down to 4~K and immersed in a magnetic field of about 0.6~T generated inside the superconducting magnet of the KLOE experiment located at the National Laboratory of Frascati of INFN. This experiment, called KLASH (KLoe magnet for Axion SearcH), has a potential sensitivity on the axion-to-photon coupling, $g_{aγγ}$, of about $6\times10^{-17}$ $\mbox{GeV}^{-1}$, reaching the region predicted by KSVZ\cite{KSVZ} and DFSZ\cite{DFSZ} models of QCD axions. We report here the status of the project.

physics.ins-det↗