Showing 1–48 of 48 results for author: Calvo, M

Characterization of Aluminum Microwave SQUID Multiplexers for CE$ν$NS Detection

Authors: James Amidei, Antoine Armatol, Corinne Augier, Louis Bailly-Salins, Guillaume Baulieu, Laurent Bergé, Julien Billard, Juliette Blé, Gaby Brenot, Guillaume Bres, Jean-Louis Bret, Alexandre Broniatowski, Martino Calvo, Antonella Cavanna, Antoine Cazes, Emanuela Celi, David Chaize, Mohammed Chala, Maurice Chapellier, Luke Chaplinsky, Ran Chen, Ion Cojocari, Jules Colas, Laurent Couraud, Elspeth Cudmore , et al. (70 additional authors not shown)

Abstract: We present the design, fabrication, and characterization of an aluminum-based six-channel microwave SQUID multiplexer ($μ$MUX) prototype for transition-edge sensor (TES) readout in the RICOCHET experiment. The device consists of aluminum coplanar-waveguide resonators and RF SQUIDs with Dolan-style Al/AlO$_x$/Al Josephson junctions. By measuring the resonator scattering parameters at a range of pro… ▽ More We present the design, fabrication, and characterization of an aluminum-based six-channel microwave SQUID multiplexer ($μ$MUX) prototype for transition-edge sensor (TES) readout in the RICOCHET experiment. The device consists of aluminum coplanar-waveguide resonators and RF SQUIDs with Dolan-style Al/AlO$_x$/Al Josephson junctions. By measuring the resonator scattering parameters at a range of probe tone frequencies, powers, and flux bias points, we demonstrate agreement between the device response and existing multiplexer models. We also characterize the noise performance in both open-loop and flux-ramping modes. With a high electron mobility transistor (HEMT) amplifier, open-loop measurements yield a flux sensitivity of 1-1.5 $μΦ_0/\sqrt{Hz}$. With flux-ramp modulation, low-frequency 1/f noise is suppressed, and the flux sensitivity is around 3-4 $μΦ_0/\sqrt{Hz}$, corresponding to a current sensitivity of 24-33 $pA/\sqrt{Hz}$ at the input coil. We further demonstrate a reduction in readout noise by incorporating a Josephson traveling-wave parametric amplifier (JTWPA) between the $μ$MUX and the HEMT. This achieves an open-loop flux sensitivity of 0.3-0.6 $μΦ_0/\sqrt{Hz}$ and an effective system noise temperature below 1 K. These results establish aluminum $μ$MUX devices as a viable and extensible readout technology for low-noise cryogenic detector arrays. △ Less

Submitted 22 May, 2026; originally announced May 2026.

Projected sensitivity to light WIMP-like particles of the BULLKID-DM experiment

Authors: Matteo Folcarelli, A. Acevedo-Rentería, L. E. Ardila-Perez, L. Bandiera, M. Calvo, M. Cappelli, R. Caravita, F. Carillo, U. Chowdhury, D. Crovo, A. Cruciani, A. D'Addabbo, D. Delicato, M. De Lucia, G. Del Castello, M. del Gallo Roccagiovine, F. Ferraro, S. Fu, R. Gartmann, M. Grassi, V. Guidi, D. Helis, T. Lari, L. Malagutti, A. Mazzolari , et al. (17 additional authors not shown)

Abstract: BULLKID-DM is an experiment designed for the direct searches of particle dark matter candidates with mass around 1 GeV, or below, and cross-section with nucleons smaller than $10^{-40}$ cm$^2$. The detector consists of a stack of diced silicon wafers, acting as arrays of particle absorbers, sensed by multiplexed Kinetic Inductance Detectors. The target will amount to 800 g subdivided in more than… ▽ More BULLKID-DM is an experiment designed for the direct searches of particle dark matter candidates with mass around 1 GeV, or below, and cross-section with nucleons smaller than $10^{-40}$ cm$^2$. The detector consists of a stack of diced silicon wafers, acting as arrays of particle absorbers, sensed by multiplexed Kinetic Inductance Detectors. The target will amount to 800 g subdivided in more than 2000 silicon dice, with the aim of controlling the background from natural radioactivity by creating a fully active structure and by applying fiducialization techniques. In this work we present the projected sensitivity of BULLKID-DM to light WIMP-like particles considering also the other future experiments in the field. △ Less

Submitted 20 January, 2026; originally announced January 2026.

Comments: 6 pages, 2 figures,

Enhanced Athermal Phonon Responsivity in a Kinetic Inductance Detector with Integrated Phonon Collectors

Authors: Leonardo Pesce, Alessio Ludovico De Santis, Martino Calvo, Matteo Cappelli, Usasi Chowdhury, Angelo Cruciani, Giorgio Del Castello, Daniele Delicato, Matteo Folcarelli, Matteo del Gallo Roccagiovine, Alessandro Monfardini, Davide Quaranta, Marco Vignati

Abstract: Cryogenic phonon detectors are adopted in light dark matter searches and coherent elastic neutrino-nucleus scattering experiments as they can achieve low energy thresholds. The phonon mediated sensing of silicon particle absorbers has already been proved with Kinetic Inductance Detectors (KIDs), acting both as sensors and athermal phonon absorbers. In this work we present the design and the perfor… ▽ More Cryogenic phonon detectors are adopted in light dark matter searches and coherent elastic neutrino-nucleus scattering experiments as they can achieve low energy thresholds. The phonon mediated sensing of silicon particle absorbers has already been proved with Kinetic Inductance Detectors (KIDs), acting both as sensors and athermal phonon absorbers. In this work we present the design and the performance of an improved detector design. In this architecture, the KID acts only as sensor and is coupled to dedicated phonon collectors. When a signal is coming from the substrate, the presence of a separated collector allows to detect an higher increase of quasi-particles density, thereby enhancing its responsivity. The meander of the KID is composed of a 77 nm trilayer wire of Aluminum-Titanium-Aluminum, while the phonon collectors are made of a 100 nm Aluminum layer and act as quasi-particles funnels. Inside the collectors, the absorbed athermal phonons generate quasi-particles which, after diffusion, are trapped in the lower-gap superconducting trilayer. The performance of this setup is compared to that of a standard phonon-mediated KID, showing an increased phonon collection efficiency by a factor of around 7. △ Less

Submitted 24 April, 2026; v1 submitted 13 January, 2026; originally announced January 2026.

Comments: Published version of the article

Journal ref: Applied Physics Letters (Vol.128, Issue 16), 2026

Real-Time Readout System Design for the BULLKID-DM Experiment: Enhancing Dark Matter Search Capabilities

Authors: T. Muscheid, R. Gartmann, L. E. Ardila-Perez, A. Acevedo-Rentería, L. Bandiera, M. Calvo, M. Cappelli, R. Caravita, F. Carillo, U. Chowdhury, D. Crovo, A. Cruciani, A. D'Addabbo, M. De Lucia, G. Del Castello, M. del Gallo Roccagiovine, D. Delicato, F. Ferraro, M. Folcarelli, S. Fu, M. Grassi, V. Guidi, D. Helis, T. Lari, L. Malagutti , et al. (19 additional authors not shown)

Abstract: The BULLKID-DM experiment aims to detect WIMP-like potential Dark Matter particles with masses below 1 GeV/c^2. Sensing these particles is challenging, as it requires nuclear recoil detectors characterized by high exposure and an energy threshold in the order of 100 eV, thus exceeding the capabilities of conventional semiconductor detectors. BULLKID-DM intends to tackle this challenge by using cry… ▽ More The BULLKID-DM experiment aims to detect WIMP-like potential Dark Matter particles with masses below 1 GeV/c^2. Sensing these particles is challenging, as it requires nuclear recoil detectors characterized by high exposure and an energy threshold in the order of 100 eV, thus exceeding the capabilities of conventional semiconductor detectors. BULLKID-DM intends to tackle this challenge by using cryogenic Kinetic Inductance Detectors (MKIDs) with exceptional energy thresholds to sense a target with a total mass of 800 g across 16 wafers, divided into over 2000 individually instrumented silicon dice. The MKIDs on each wafer are coupled to a single transmission line and read using a frequency division multiplexing approach by the room-temperature data acquisition. In this contribution, we describe and assess the design of the room-temperature readout electronics system, including the selected hardware components and the FPGA firmware which contains the real-time signal processing stages for tone generation, frequency demultiplexing, and event triggering. We evaluate the system on the ZCU216 board, a commercial evaluation card built around a Radio-Frequency System-on-Chip (RFSoC) with integrated high-speed DACs and ADCs, and connected it to a custom-designed analog front-end for signal conditioning. △ Less

Submitted 20 October, 2025; originally announced October 2025.

Comments: Conference: LTD2025 (submitted to IEEE Transaction on Applied Superconductivity - Special issue LTD2025)

Energy calibration of bulk events in the BULLKID detector

Authors: M. Folcarelli, D. Delicato, A. Acevedo-Rentería, L. E. Ardila-Perez, L. Bandiera, M. Calvo, M. Cappelli, R. Caravita, F. Carillo, U. Chowdhury, D. Crovo, A. Cruciani, A. D'Addabbo, M. De Lucia, G. Del Castello, M. del Gallo Roccagiovine, F. Ferraro, S. Fu, R. Gartmann, M. Grassi, V. Guidi, D. Helis, T. Lari, L. Malagutti, A. Mazzolari , et al. (17 additional authors not shown)

Abstract: BULLKID is a cryogenic, solid-state detector designed for direct searches of particle Dark Matter candidates, with mass $\lesssim 1$ GeV/c$^2$, and coherent neutrino-nucleus scattering. It is based on an array of dice carved in 5 mm thick silicon crystal, sensed by phonon-mediated Kinetic Inductance Detectors. In previous works, the array was calibrated with bursts of optical photons, which are ab… ▽ More BULLKID is a cryogenic, solid-state detector designed for direct searches of particle Dark Matter candidates, with mass $\lesssim 1$ GeV/c$^2$, and coherent neutrino-nucleus scattering. It is based on an array of dice carved in 5 mm thick silicon crystal, sensed by phonon-mediated Kinetic Inductance Detectors. In previous works, the array was calibrated with bursts of optical photons, which are absorbed in the first hundreds nanometers of the dice and give rise to surface events. In this work, we present the reconstruction of bulk events through the 59.5 keV $γ$-ray generated by an $^{241}$Am source, which emulates more closely the interaction of Dark Matter and neutrinos. The peak resolution is $5\%~(σ)$ and its position is shifted by less than $10\%$ with respect to the optical calibration. We observe that the resolution is further improved by a factor $2$ combining the signal from neighboring dice. These results confirm the performance of the detector in view of the physics goals of the BULLKID-DM experiment for dark matter search. △ Less

Submitted 20 October, 2025; originally announced October 2025.

Comments: 7 pages, 5 figures

Dark characterization of Ti/Al LEKIDs for the search of axions in the W-band

Authors: Victor Rollano, Alejandro Pascual Laguna, David Rodriguez, Martino Calvo, Maria Teresa Magaz, Daniel Granados, Alessandro Monfardini, Alicia Gomez

Abstract: We report the electrical (dark) characterization of lumped-element kinetic inductance detectors (LEKIDs) fabricated from a Titanium/Aluminum bilayer and designed for broadband absorption in the W-band (75-110 GHz). These detectors are prototypes for future QCD axion search experiments within the Canfranc Axion Detection Experiment (CADEx), which demand sub 1e-19 W/Hz^0.5 sensitivities under low op… ▽ More We report the electrical (dark) characterization of lumped-element kinetic inductance detectors (LEKIDs) fabricated from a Titanium/Aluminum bilayer and designed for broadband absorption in the W-band (75-110 GHz). These detectors are prototypes for future QCD axion search experiments within the Canfranc Axion Detection Experiment (CADEx), which demand sub 1e-19 W/Hz^0.5 sensitivities under low optical backgrounds. We combine a Mattis-Bardeen analysis to the temperature dependence of the detector parameters with noise spectroscopy to determine the electrical noise equivalent power (NEP). The minimum measured value for the electrical NEP is 3e-19 W/Hz0.5. Across the measured temperature range, we find that quasiparticle lifetime deviates from the expected BCS recombination law. Our analysis suggests that non-equilibrium relaxation is governed by spatial inhomogeneities in the superconducting gap and phonon diffusion effects. This work sets the road-map to achieve suitable and ultra-sensitive detectors in the W-band for dark matter axion search experiments. △ Less

Submitted 2 October, 2025; originally announced October 2025.

Cross-Polarization Reduction in Kinetic Inductance Detectors Based on Quasi-Lumped Resonators

Authors: Victor Rollano, Martino Calvo, Alejandro Pascual Laguna, David Rodriguez, Maria Teresa Magaz, Beatriz Aja, Luisa de la Fuente, Daniel Granados, Alessandro Monfardini, Alicia Gomez

Abstract: Kinetic Inductance Detectors (KIDs) have emerged as a leading technology for millimeter- and submillimeter-wave astronomy due to their high sensitivity, natural multiplexing capabilities and scalable fabrication. In polarization-sensitive applications-such as Cosmic Microwave Background (CMB) studies-cross-polarization, or unintended response to the orthogonal polarization, poses a significant lim… ▽ More Kinetic Inductance Detectors (KIDs) have emerged as a leading technology for millimeter- and submillimeter-wave astronomy due to their high sensitivity, natural multiplexing capabilities and scalable fabrication. In polarization-sensitive applications-such as Cosmic Microwave Background (CMB) studies-cross-polarization, or unintended response to the orthogonal polarization, poses a significant limitation to measurement fidelity. This work investigates the origin of cross-polarization in meandered Lumped Element KIDs (LEKIDs), with particular emphasis on the role of parasitic currents in the interdigitated capacitor. A comparative study between conventional LEKIDs and a quasi-lumped resonator design is presented, demonstrating that removing the capacitive element may improve cross-polarization discrimination, confirming the capacitor's contribution to polarization leakage. △ Less

Submitted 2 October, 2025; originally announced October 2025.

Characterization of mini-CryoCube detectors from the Ricochet experiment commissioning at the Institut Laue-Langevin

Authors: Antoine Armatol, Corinne Augier, Louis Bailly-Salins, Guillaume Baulieu, Laurent Bergé, Julien Billard, Juliette Blé, Guillaume Bres, Jean-Louis Bret, Alexandre Broniatowski, Martino Calvo, Antonella Cavanna, Antoine Cazes, Emanuela Celi, David Chaize, Mohammed Chala, Maurice Chappellier, Luke Chaplinsky, Guillaume Chemin, Ran Chen, Jules Colas, Laurent Couraud, Elspeth Cudmore, Maryvonne De Jesus, Nicole Dombrowski , et al. (61 additional authors not shown)

Abstract: The Ricochet experiment aims to measure the coherent elastic neutrino-nucleus scattering process from antineutrinos emitted by a research nuclear reactor operated by the Institut Laue-Langevin (Grenoble, France). This article presents a description of the Ricochet experimental installation and the detector performance achieved during its commissioning with a mini-CryoCube module consisting of thre… ▽ More The Ricochet experiment aims to measure the coherent elastic neutrino-nucleus scattering process from antineutrinos emitted by a research nuclear reactor operated by the Institut Laue-Langevin (Grenoble, France). This article presents a description of the Ricochet experimental installation and the detector performance achieved during its commissioning with a mini-CryoCube module consisting of three 42-gram germanium cryogenic calorimeters. The baseline resolutions and background levels are reported both during reactor-on and reactor-off periods, and as noise mitigation techniques were improved. A baseline resolution of 40 eV electron equivalent was achieved for the ionization channel after setup improvements, and the phonon channel resolutions ranged from 50 to 80 eV of total phonon energy. In the energy region from 2 to 7 keV, a nuclear recoil rate of 15(2) events/(kg day keV) is measured during the reactor-off period selecting events in coincidence with muon veto signals. This rate is in agreement with the cosmogenic neutron rate calculated from GEANT4 simulations. After the rejection of events in coincidence with signals in the muon veto detectors, a combined 90% C.L. limit on the nuclear recoil background of < 9 events/(kg day keV) is obtained in that energy region during the reactor-on period, which is compatible with our GEANT4 model calculation corresponding to a total rate of 5 events/(kg day keV). The sensitivity of this analysis was however found to be limited by a surface event contamination which is currently being addressed by the Ricochet Collaboration with upgraded detectors. △ Less

Submitted 30 July, 2025; originally announced July 2025.

Comments: 16 pages, 9 figures

Journal ref: Phys. Rev. D 112, 112019 (2025)

High-precision polarization measurements with Lumped Element Kinetic Inductance Detectors

Authors: Sofia Savorgnano, Andrea Catalano, Juan-Francisco Macías Perez, Julien Bounmy, Olivier Bourrion, Martino Calvo, Olivier Choulet, Gregory Garde, Anne Gerardin, Mile Kusulja, Alessandro Monfardini, Nicolas Ponthieu, Damien Tourres, Francis Vezzu

Abstract: This work aims to demonstrate that two arrays of Lumped Element Kinetic Inductance Detectors (LEKIDs), when employed in filled array configuration and separated by an external linear polarizer oriented at 45 degrees, can achieve the precision required by next-generation cosmological experiments. The focus here is on validating their ability to meet stringent uncertainty requirements, in particular… ▽ More This work aims to demonstrate that two arrays of Lumped Element Kinetic Inductance Detectors (LEKIDs), when employed in filled array configuration and separated by an external linear polarizer oriented at 45 degrees, can achieve the precision required by next-generation cosmological experiments. The focus here is on validating their ability to meet stringent uncertainty requirements, in particular for polarization angle reconstruction. To achieve this, the uncertainties in the reconstruction of the polarization angle have been characterized in the laboratory using a dedicated closed-circuit 100 mK dilution cryostat. This is optically coupled to a Martin-Puplett interferometer and a custom-designed sky simulator equipped with both photometric and polarized sources, allowing one to reproduce realistic ground-based observation conditions. This experimental setup allows us to generate intensity and polarization maps with diffraction-limited resolution, allowing us to determine the polarization angles and their associated uncertainties. The results show performance in line with expectations for the next generation CMB experiments. The polarization angle was reconstructed with an uncertainty of 6.5 arcmin. △ Less

Submitted 30 June, 2025; originally announced June 2025.

Comments: 12 pages, 13 figures; accepted for publication by A&A on June 28, 2025

Journal ref: A&A 700, A114 (2025)

Spatially-Controlled Planar Guided Crystallization of Low-Loss Phase Change Materials for Programmable Photonics

Authors: Fouad Bentata, Arnaud Taute, Capucine Laprais, Régis Orobtchouk, Eva Kempf, Alban Gassenq, Yves Pipon, Michele Calvo, Valérie Martinez, Stéphane Monfray, Guillaume Saint-Girons, Nicolas Baboux, Hai Son Nguyen, Xavier Letartre, Lotfi Berguiga, Patrice Genevet, Sébastien Cueff

Abstract: Photonic integrated devices are progressively evolving beyond passive components into fully programmable systems, notably driven by the progress in chalcogenide phase-change materials (PCMs) for non-volatile reconfigurable nanophotonics. However, the stochastic nature of their crystal grain formation results in strong spatial and temporal crystalline inhomogeneities. Here, we propose the concept o… ▽ More Photonic integrated devices are progressively evolving beyond passive components into fully programmable systems, notably driven by the progress in chalcogenide phase-change materials (PCMs) for non-volatile reconfigurable nanophotonics. However, the stochastic nature of their crystal grain formation results in strong spatial and temporal crystalline inhomogeneities. Here, we propose the concept of spatially-controlled planar guided crystallization, a novel method for programming the growth of optically homogeneous low-loss Sb2S3 PCM, leveraging the seeded directional and progressive crystallization within confined channels. This guided crystallization method is experimentally shown to circumvent the current limitations of conventional PCM-based nanophotonic devices, including a multilevel non-volatile optical phase-shifter exploiting a silicon nitride-based Mach-Zehnder interferometer, and a programmable metasurface with spectrally reconfigurable bound state in the continuum. Precisely controlling the growth of PCMs to ensure optically uniform crystalline properties across devices is the cornerstone for the industrial development of non-volatile reconfigurable photonic integrated circuits. △ Less

Submitted 29 September, 2025; v1 submitted 23 April, 2025; originally announced April 2025.

Strain Engineering of Magnetoresistance and Magnetic Anisotropy in CrSBr

Authors: Eudomar Henríquez-Guerra, Alberto M. Ruiz, Marta Galbiati, Alvaro Cortes-Flores, Daniel Brown, Esteban Zamora-Amo, Lisa Almonte, Andrei Shumilin, Juan Salvador-Sánchez, Ana Pérez-Rodríguez, Iñaki Orue, Andrés Cantarero, Andres Castellanos-Gomez, Federico Mompeán, Mar Garcia-Hernandez, Efrén Navarro-Moratalla, Enrique Díez, Mario Amado, José J. Baldoví, M. Reyes Calvo

Abstract: Tailoring magnetoresistance and magnetic anisotropy in van der Waals magnetic materials is essential for advancing their integration into technological applications. In this regard, strain engineering has emerged as a powerful and versatile strategy to control magnetism at the two-dimensional (2D) limit. Here, we demonstrate that compressive biaxial strain significantly enhances the magnetoresista… ▽ More Tailoring magnetoresistance and magnetic anisotropy in van der Waals magnetic materials is essential for advancing their integration into technological applications. In this regard, strain engineering has emerged as a powerful and versatile strategy to control magnetism at the two-dimensional (2D) limit. Here, we demonstrate that compressive biaxial strain significantly enhances the magnetoresistance and magnetic anisotropy of few-layer CrSBr flakes. Strain is efficiently transferred to the flakes from the thermal compression of a polymeric substrate upon cooling, as confirmed by temperature-dependent Raman spectroscopy. This strain induces a remarkable increase in the magnetoresistance ratio and in the saturation fields required to align the magnetization of CrSBr along each of its three crystalographic directions, reaching a twofold enhancement along the magnetic easy axis. This enhancement is accompanied by a subtle reduction of the Néel temperature by ~10K. Our experimental results are fully supported by first-principles calculations, which link the observed effects to a strain-driven modification in interlayer exchange coupling and magnetic anisotropy energy. These findings establish strain engineering as a key tool for fine-tuning magnetotransport properties in 2D magnetic semiconductors, paving the way for implementation in spintronics and information storage devices. △ Less

Submitted 31 July, 2025; v1 submitted 14 April, 2025; originally announced April 2025.

Journal ref: Advanced Materials (2025) 2506695

Germanium target sensed by phonon-mediated kinetic inductance detectors

Authors: D. Delicato, D. Angelone, L. Bandiera, M. Calvo, M. Cappelli, U. Chowdhury, G. Del Castello, M. Folcarelli, M. del Gallo Roccagiovine, V. Guidi, G. L. Pesce, M. Romagnoni, A. Cruciani, A. Mazzolari, A. Monfardini, M. Vignati

Abstract: Cryogenic phonon detectors are adopted in experiments searching for dark matter interactions or coherent elastic neutrino-nucleus scattering, thanks to the low energy threshold they can achieve. The phonon-mediated sensing of particle interactions in passive silicon absorbers has been demonstrated with Kinetic Inductance Detectors (KIDs). Targets with neutron number larger than silicon, however, f… ▽ More Cryogenic phonon detectors are adopted in experiments searching for dark matter interactions or coherent elastic neutrino-nucleus scattering, thanks to the low energy threshold they can achieve. The phonon-mediated sensing of particle interactions in passive silicon absorbers has been demonstrated with Kinetic Inductance Detectors (KIDs). Targets with neutron number larger than silicon, however, feature higher cross section to neutrinos while multi-target absorbers in dark matter experiments would provide a stronger evidence of a possible signal. In this work we present the design, fabrication and operation of KIDs coupled to a germanium absorber, achieving phonon-sensing performance comparable to silicon absorbers. The device introduced in this work is a proof of concept for a scalable neutrino detector and for a multi-target dark matter experiment. △ Less

Submitted 15 April, 2025; v1 submitted 10 December, 2024; originally announced December 2024.

Comments: 3 Figures, 2 Tables, 5 pages

Magnetic field tunable spectral response of kinetic inductance detectors

Authors: F. Levy-Bertrand, M. Calvo, U. Chowdhury, A. Gomez, J. Goupy, A. Monfardini

Abstract: We tune the onset of optical response in aluminium kinetic inductance detectors from a natural cutoff frequency of 90 GHz to 60 GHz by applying an external magnetic field. The change in spectral response is due to the decrease of the superconducting gap, from 90 GHz at zero magnetic field to 60 GHz at a magnetic field of around 3 mT. We characterize the variation of the superconducting gap, the de… ▽ More We tune the onset of optical response in aluminium kinetic inductance detectors from a natural cutoff frequency of 90 GHz to 60 GHz by applying an external magnetic field. The change in spectral response is due to the decrease of the superconducting gap, from 90 GHz at zero magnetic field to 60 GHz at a magnetic field of around 3 mT. We characterize the variation of the superconducting gap, the detector frequency shift and the internal quality factor as a function of the applied field. In principle, the magnetic field tunable response could be used to make spectroscopic measurements. In practice, the internal quality factor behaves hysteretically with the magnetic field due to the presence of vortices in the thin superconducting film. We conclude by discussing possible solutions to achieve spectroscopy measurements using kinetic inductance detectors and magnetic field. △ Less

Submitted 28 January, 2025; v1 submitted 5 September, 2024; originally announced September 2024.

Journal ref: Appl. Phys. Lett. 126, 042602 (2025)

Photoinduced Spin Centers in Photocatalytic Metal-Organic Framework UiO-66

Authors: Anastasiia Kultaeva, Timur Biktagirov, Andreas Sperlich, Patrick Dörflinger, Mauricio E. Calvo, Eugenio Otal, Vladimir Dyakonov

Abstract: Metal-Organic frameworks (MOFs) are promising candidates for advanced photocatalytically active materials. These porous crystalline compounds have large active surface areas and structural tunability and are thus highly competitive with oxides, the well-established material class for photocatalysis. However, due to their complex organic and coordination chemistry composition, photophysical mechani… ▽ More Metal-Organic frameworks (MOFs) are promising candidates for advanced photocatalytically active materials. These porous crystalline compounds have large active surface areas and structural tunability and are thus highly competitive with oxides, the well-established material class for photocatalysis. However, due to their complex organic and coordination chemistry composition, photophysical mechanisms involved in the photocatalytic processes in MOFs are still not well understood. Employing electron paramagnetic resonance (EPR) spectroscopy and time-resolved photoluminescence spectroscopy (trPL), the fundamental processes of electron and hole generation are investigated, as well as capture events that lead to the formation of various radical species in UiO-66, an archetypical MOF photocatalyst. A manifold of photoinduced electron spin centers is detected, which is subsequently analyzed and identified with the help of density-functional theory (DFT) calculations. Under UV illumination, the symmetry, g-tensors and lifetimes of three distinct contributions are revealed: a surface O2-radical, a light-induced electron-hole pair, and a triplet exciton. Notably, the latter was found to emit (delayed) fluorescence. Our findings provide new insights into the photoinduced charge transfer processes, which are the basis of photocatalytic activity in UiO-66. This sets the stage for further studies on photogenerated spin centers in this and similar MOF materials. △ Less

Submitted 24 October, 2024; v1 submitted 23 April, 2024; originally announced April 2024.

Comments: 23 pages, 12 figures

Journal ref: Adv. Funct. Mater. 2024, 2413297

Intense and Stable Blue Light Emission from CsPbBr$_3$/Cs$_4$PbBr$_6$ Heterostructures Embedded in Transparent Nanoporous Films

Authors: Carlos Romero-Perez, Natalia Fernandez Delgado, Miriam Herrera Collado, Mauricio E. Calvo, Hernan Miguez

Abstract: Lead halide perovskite nanocrystals are attractive for light emitting devices both as electroluminescent and color converting materials, since they combine intense and narrow emissions with good charge injection and transport properties. However, most perovskite nanocrystals shine at green and red wavelengths, the observation of intense and stable blue emission still being a challenging target. In… ▽ More Lead halide perovskite nanocrystals are attractive for light emitting devices both as electroluminescent and color converting materials, since they combine intense and narrow emissions with good charge injection and transport properties. However, most perovskite nanocrystals shine at green and red wavelengths, the observation of intense and stable blue emission still being a challenging target. In this work, we report a method to attain intense and enduring blue emission (470-480 nm), with a photoluminescence quantum yield (PLQY) of 40%, originated from very small CsPbBr$_3$ nanocrystals (diameter<3nm) formed by controllably exposing Cs$_4$PbBr$_6$ to humidity. This process is mediated by the void network of a mesoporous transparent scaffold in which the zero-dimensional (0D) Cs$_4$PbBr$_6$ lattice is embedded, which allows the fine control over water adsorption and condensation that determines the optimization of the synthetic procedure and, eventually, the nanocrystal size. By temperature dependent photoemission analysis of samples with different [CsPbBr$_3$]/[Cs$_4$PbBr$_6$] volume ratios, we show that the bright blue emission observed results from the efficient charge transfer to the CsPbBr$_3$ inclusions from the Cs$_4$PbBr$_6$ host. Our approach provides a means to attain highly efficient transparent blue light emitting films that complete the palette offered by perovskite nanocrystals for lighting and display applications. △ Less

Submitted 13 March, 2024; originally announced March 2024.

Comments: 4 figures, supporting information available

Low-energy spectrum of the BULLKID detector array operated on surface

Authors: D. Delicato, A. Ahmad, L. Bandiera, M. Calvo, M. Cappelli, G. Del Castello, M. del Gallo Roccagiovine, M. Giammei, V. Guidi, D. Maiello, V. Pettinacci, M. Romagnoni, M. Tamisari, A. Cruciani, A. Mazzolari, A. Monfardini, M. Vignati

Abstract: We present the first continuous operation in a surface lab of BULLKID, a detector for searches of light Dark Matter and precision measurements of the coherent and elastic neutrino-nucleus scattering. The detector consists of an array of 60 cubic silicon particle absorbers of 0.34 g each, sensed by cryogenic kinetic inductance detectors. The data presented focusses on one of the central elements of… ▽ More We present the first continuous operation in a surface lab of BULLKID, a detector for searches of light Dark Matter and precision measurements of the coherent and elastic neutrino-nucleus scattering. The detector consists of an array of 60 cubic silicon particle absorbers of 0.34 g each, sensed by cryogenic kinetic inductance detectors. The data presented focusses on one of the central elements of the array and on its surrounding elements used as veto. The energy spectrum resulting from an exposure of 39 hours to ambient backgrounds, obtained without radiation shields, is flat at the level of $(2.0\pm0.1\,{\rm stat.}\pm0.2\,{\rm syst.})\times10^6$ counts / keV kg days down to the energy threshold of $160\pm13$ eV. The data analysis demonstrates the unique capability of rejecting backgrounds generated from interactions in other sites of the array, stemming from the segmented and monolithic structure of the detector. △ Less

Submitted 17 April, 2024; v1 submitted 28 August, 2023; originally announced August 2023.

Journal ref: Eur. Phys. J. C 84 (2024) 353

Results from a Prototype TES Detector for the Ricochet Experiment

Authors: Ricochet Collaboration, C. Augier, G. Baulieu, V. Belov, L. Bergé, J. Billard, G. Bres, J-. L. Bret, A. Broniatowski, M. Calvo, A. Cazes, D. Chaize, M. Chala, C. L. Chang, M. Chapellier, L. Chaplinsky, G. Chemin, R. Chen, J. Colas, E. Cudmore, M. De Jesus, P. de Marcillac, L. Dumoulin, O. Exshaw, S. Ferriol , et al. (66 additional authors not shown)

Abstract: Coherent elastic neutrino-nucleus scattering (CE$ν$NS) offers valuable sensitivity to physics beyond the Standard Model. The Ricochet experiment will use cryogenic solid-state detectors to perform a precision measurement of the CE$ν$NS spectrum induced by the high neutrino flux from the Institut Laue-Langevin nuclear reactor. The experiment will employ an array of detectors, each with a mass of… ▽ More Coherent elastic neutrino-nucleus scattering (CE$ν$NS) offers valuable sensitivity to physics beyond the Standard Model. The Ricochet experiment will use cryogenic solid-state detectors to perform a precision measurement of the CE$ν$NS spectrum induced by the high neutrino flux from the Institut Laue-Langevin nuclear reactor. The experiment will employ an array of detectors, each with a mass of $\sim$30 g and a targeted energy threshold of 50 eV. Nine of these detectors (the "Q-Array") will be based on a novel Transition-Edge Sensor (TES) readout style, in which the TES devices are thermally coupled to the absorber using a gold wire bond. We present initial characterization of a Q-Array-style detector using a 1 gram silicon absorber, obtaining a baseline root-mean-square resolution of less than 40 eV. △ Less

Submitted 12 January, 2024; v1 submitted 28 April, 2023; originally announced April 2023.

Comments: 18 pages, 8 figures

Journal ref: Nuclear Inst. and Methods in Physics Research, A 1057 (2023) 168765

Scanning Reflectance Anisotropy Microscopy for Multi-Material Strain Mapping

Authors: Joan Sendra, Fabian Haake, Micha Calvo, Henning Galinski, Ralph Spolenak

Abstract: Strain-engineering of materials encompasses significant elastic deformation and leads to breaking of the lattice symmetry and as a consequence to the emergence of optical anisotropy. However, the capability to image and map local strain fields by optical microscopy is currently limited to specific materials. Here, we introduce a broadband scanning reflectance anisotropy microscope as a phase-sensi… ▽ More Strain-engineering of materials encompasses significant elastic deformation and leads to breaking of the lattice symmetry and as a consequence to the emergence of optical anisotropy. However, the capability to image and map local strain fields by optical microscopy is currently limited to specific materials. Here, we introduce a broadband scanning reflectance anisotropy microscope as a phase-sensitive multi-material optical platform for strain mapping. The microscope produces hyperspectral images with diffraction-limited sub-micron resolution of the near-normal incidence ellipsometric response of the sample, which is related to elastic strain by means of the elasto-optic effect. We demonstrate cutting edge strain sensitivity using a variety of materials, such as metasurfaces, semiconductors and metals. The versatility of the method to study the breaking of the lattice symmetry by simple reflectance measurements opens up the possibility to carry out non-destructive mechanical characterization of multi-material components, such as wearable electronics and optical semiconductor devices. △ Less

Submitted 9 February, 2023; v1 submitted 8 February, 2023; originally announced February 2023.

Comments: 9 pages, 4 figures. Added missing department in the authors' affiliation

Journal ref: Adv. Funct. Mater. 2023, 33, 2302179

A millimetre-wave superconducting hyper-spectral device

Authors: Usasi Chowdhury, Florence Levy-Bertrand, Martino Calvo, Johannes Goupy, Alessandro Monfardini

Abstract: Millimetre-wave observations represent an important tool for Cosmology studies. The Line Intensity Mapping (LIM) technique has been proposed to map in three dimensions the specific intensity due to line (e.g. [CII], CO) emission, for example from the primordial galaxies, as a function of redshift. Hyper-spectral integrated devices have the potential to replace the current Fourier transform, or the… ▽ More Millimetre-wave observations represent an important tool for Cosmology studies. The Line Intensity Mapping (LIM) technique has been proposed to map in three dimensions the specific intensity due to line (e.g. [CII], CO) emission, for example from the primordial galaxies, as a function of redshift. Hyper-spectral integrated devices have the potential to replace the current Fourier transform, or the planned Fabry-Perot-based instruments operating at millimetre and sub-millimetre wavelengths. The aim is to perform hyper-spectral mapping, with a spectral resolution R= 100-1000, over large, i.e. thousands of beams, instantaneous patches of the Sky. The innovative integrated device that we have developed allows avoiding moving parts, complicated and/or dispersive optics or tunable filters to be operated at cryogenic temperatures. The prototype hyper-spectral focal plane is sensitive in the 75-90GHz range and contains nineteen horns for sixteen spectral-imaging channels, each selecting a frequency band of about 0.1GHz. For each channel a conical horn antenna, coupled to a planar superconducting resonant absorber made of thin aluminium, collects the radiation. A capacitively coupled titanium-aluminium bilayer Lumped Element Kinetic Inductance Detector (LEKID) is then in charge of dissipating and sensing the super-current established in the resonant absorber. The prototype is fabricated with only two photo-lithography steps over a commercial mono-crystalline sapphire substrate. It exhibits a spectral resolution of about 800. The optical noise equivalent power of the best channels is in the observational relevant 4E-17W/sqrt(Hz) range. The average sensitivity of all the channels is around 1E-16W/sqrt(Hz). The device, as expected from 3-D simulations, is polarisation-sensitive, paving the way to spectro-polarimetry measurements over very large instantaneous field-of-views. △ Less

Submitted 27 August, 2023; v1 submitted 9 November, 2022; originally announced November 2022.

Comments: Published in RAS Techniques and Instruments, rzad038, open access

BULLKID: Monolithic array of particle absorbers sensed by Kinetic Inductance Detectors

Authors: A. Cruciani, L. Bandiera, M. Calvo, N. Casali, I. Colantoni, G. Del Castello, M. del Gallo Roccagiovine, D. Delicato, M. Giammei, V. Guidi, J. Goupy, V. Pettinacci, G. Pettinari, M. Romagnoni, M. Tamisari, A. Mazzolari, A. Monfardini, M. Vignati

Abstract: We introduce BULLKID, an innovative phonon detector consisting of an array of dices acting as particle absorbers sensed by multiplexed Kinetic Inductance Detectors (KIDs). The dices are carved in a thick crystalline wafer and form a monolithic structure. The carvings leave a thin common disk intact in the wafer, acting both as holder for the dices and as substrate for the KID lithography. The prot… ▽ More We introduce BULLKID, an innovative phonon detector consisting of an array of dices acting as particle absorbers sensed by multiplexed Kinetic Inductance Detectors (KIDs). The dices are carved in a thick crystalline wafer and form a monolithic structure. The carvings leave a thin common disk intact in the wafer, acting both as holder for the dices and as substrate for the KID lithography. The prototype presented consists of an array of 64 dices of 5.4x5.4x5 mm$^3$ carved in a 3" diameter, 5 mm thick silicon wafer, with a common disk 0.5 mm thick hosting a 60 nm patterned aluminum layer. The resulting array is highly segmented but avoids the use of dedicated holding structures for each unit. Despite the fact that the uniformity of the KID electrical response across the array needs optimization, the operation of 8 units with similar features shows, on average, a baseline energy resolution of $26\pm7$ eV. This makes it a suitable detector for low-energy processes such as direct interactions of dark matter and coherent elastic neutrino-nucleus scattering. △ Less

Submitted 29 September, 2022; originally announced September 2022.

Journal ref: Appl. Phys. Lett. 121 (2022) 213504

A horn-coupled millimeter-wave on-chip spectrometer based on Lumped Element Kinetic Inductance Detectors

Authors: Usasi Chowdhury, Florence Levy-Bertrand, Martino Calvo, Johannes Goupy, Alessandro Monfardini

Abstract: Context. Millimetre-wave astronomy is an important tool for both general astrophysics studies and cosmology. A large number of unidentified sources are being detected by the large field-of-view continuum instruments operating on large telescopes. Aims. New smart focal planes are needed to bridge the gap between large bandwidth continuum instruments operating on single dish telescopes and the hig… ▽ More Context. Millimetre-wave astronomy is an important tool for both general astrophysics studies and cosmology. A large number of unidentified sources are being detected by the large field-of-view continuum instruments operating on large telescopes. Aims. New smart focal planes are needed to bridge the gap between large bandwidth continuum instruments operating on single dish telescopes and the high spectral and angular resolution interferometers (e.g. ALMA in Chile, NOEMA in France). The aim is to perform low-medium spectral resolution observations and select a lower number of potentially interesting sources, i.e. high-redshift galaxies, for further follow-up. Methods. We have designed, fabricated and tested an innovative on-chip spectrometer sensitive in the 85-110~GHz range. It contains sixteen channels selecting a frequency band of about 0.2 GHz each. A conical horn antenna coupled to a slot in the ground plane collects the radiation and guides it to a mm-wave microstrip transmission line placed on the other side of the mono-crystalline substrate. The mm-wave line is coupled to a filter-bank. Each filter is capacitively coupled to a Lumped Element Kinetic Inductance Detector (LEKID). The microstrip configuration allows to benefit from the high quality, i.e. low losses, mono-crystalline substrate, and at the same time prevents direct, i.e. un-filtered, LEKID illumination. Results. The prototype spectrometer exhibit a spectral resolution R = lambda / Delta_lambda = 300. The optical noise equivalent power is in the low 1E-16W/sqrt(Hz) range for an incoming power of about 0.2pW per channel. The device is polarisation-sensitive, with a cross-polarisation lower than 1% for the best channels. △ Less

Submitted 6 September, 2022; originally announced September 2022.

Comments: Submitted to Astronomy & Astrophysics

Journal ref: A&A 672, A7 (2023)

CONCERTO: Readout and control electronics

Authors: O. Bourrion, C. Hoarau, J. Bounmy, D. Tourres, C. Vescovi J. -L. Bouly, N. Ponchant, A. Beelen, M. Calvo, A. Catalano, J. Goupy, G. Lagache, J. -F. Macías-Pérez, J. Marpaud, A. Monfardini

Abstract: The CONCERTO spectral-imaging instrument was installed at the Atacama Pathfinder EXperiment (APEX) 12-meter telescope in April 2021. It has been designed to look at radiation emitted by ionised carbon atoms, [CII], and use the "intensity Mapping" technique to set the first constraints on the power spectrum of dusty star-forming galaxies. The instrument features two arrays of 2152 pixels constitute… ▽ More The CONCERTO spectral-imaging instrument was installed at the Atacama Pathfinder EXperiment (APEX) 12-meter telescope in April 2021. It has been designed to look at radiation emitted by ionised carbon atoms, [CII], and use the "intensity Mapping" technique to set the first constraints on the power spectrum of dusty star-forming galaxies. The instrument features two arrays of 2152 pixels constituted of Lumped Element Kinectic Inductance Detectors (LEKID) operated at cryogenic temperatures, cold optics and a fast Fourier Transform Spectrometer (FTS). To readout and operate the instrument, a newly designed electronic system hosted in five microTCA crates and composed of twelve readout boards and two control boards was designed and commissioned. The architecture and the performances are presented in this paper. △ Less

Submitted 21 October, 2022; v1 submitted 16 August, 2022; originally announced August 2022.

Journal ref: Journal of Instrumentation, Volume 17, October 2022: P10047

Fast neutron background characterization of the future Ricochet experiment at the ILL research nuclear reactor

Authors: C. Augier, G. Baulieu, V. Belov, L. Berge, J. Billard, G. Bres, J. -L. Bret, A. Broniatowski, M. Calvo, A. Cazes, D. Chaize, M. Chapellier, L. Chaplinsky, G. Chemin, R. Chen, J. Colas, M. De Jesus, P. de Marcillac, L. Dumoulin, O. Exshaw, S. Ferriol, E. Figueroa-Feliciano, J. -B. Filippini, J. A. Formaggio, S. Fuard , et al. (58 additional authors not shown)

Abstract: The future Ricochet experiment aims at searching for new physics in the electroweak sector by providing a high precision measurement of the Coherent Elastic Neutrino-Nucleus Scattering (CENNS) process down to the sub-100 eV nuclear recoil energy range. The experiment will deploy a kg-scale low-energy-threshold detector array combining Ge and Zn target crystals 8.8 meters away from the 58 MW resear… ▽ More The future Ricochet experiment aims at searching for new physics in the electroweak sector by providing a high precision measurement of the Coherent Elastic Neutrino-Nucleus Scattering (CENNS) process down to the sub-100 eV nuclear recoil energy range. The experiment will deploy a kg-scale low-energy-threshold detector array combining Ge and Zn target crystals 8.8 meters away from the 58 MW research nuclear reactor core of the Institut Laue Langevin (ILL) in Grenoble, France. Currently, the Ricochet collaboration is characterizing the backgrounds at its future experimental site in order to optimize the experiment's shielding design. The most threatening background component, which cannot be actively rejected by particle identification, consists of keV-scale neutron-induced nuclear recoils. These initial fast neutrons are generated by the reactor core and surrounding experiments (reactogenics), and by the cosmic rays producing primary neutrons and muon-induced neutrons in the surrounding materials. In this paper, we present the Ricochet neutron background characterization using $^3$He proportional counters which exhibit a high sensitivity to thermal, epithermal and fast neutrons. We compare these measurements to the Ricochet Geant4 simulations to validate our reactogenic and cosmogenic neutron background estimations. Eventually, we present our estimated neutron background for the future Ricochet experiment and the resulting CENNS detection significance. △ Less

Submitted 2 August, 2022; originally announced August 2022.

Comments: 14 pages, 14 figures, 1 table

CONCERTO : Digital processing for finding and tuning LEKIDs

Authors: Julien Bounmy, Christophe Hoarau, Juan-Francisco Macías-Pérez, Alexandre Beelen, Alain Benoît, Olivier Bourrion, Martino Calvo, Andrea Catalano, Alessandro Fasano, Johannes Goupy, Guilaine Lagache, Julien Marpaud, Alessandro Monfardini

Abstract: We describe the on-line algorithms developed to probe Lumped Element Kinetic Inductance Detectors (LEKID) in this paper. LEKIDs are millimeter wavelength detectors for astronomy. LEKID arrays are currently operated in different instruments as: NIKA2 at the IRAM telescope in Spain, KISS at the Teide Observatory telescope in Tenerife, and CONCERTO at the APEX 12-meter telescope in Chile. LEKIDs are… ▽ More We describe the on-line algorithms developed to probe Lumped Element Kinetic Inductance Detectors (LEKID) in this paper. LEKIDs are millimeter wavelength detectors for astronomy. LEKID arrays are currently operated in different instruments as: NIKA2 at the IRAM telescope in Spain, KISS at the Teide Observatory telescope in Tenerife, and CONCERTO at the APEX 12-meter telescope in Chile. LEKIDs are superconducting microwave resonators able to detect the incoming light at millimeter wavelengths and they are well adapted for frequency multiplexing (currently up to 360 pixels on a single microwave guide). Nevertheless, their use for astronomical observations requires specific readout and acquisition systems both to deal with the instrumental and multiplexing complexity, and to adapt to the observational requirements (e.g. fast sampling rate, background variations, on-line calibration, photometric accuracy, etc). This paper presents the different steps of treatment from identifying the resonance frequency of each LEKID to the continuous automatic control of drifting LEKID resonance frequencies induced by background variations. △ Less

Submitted 7 September, 2022; v1 submitted 23 June, 2022; originally announced June 2022.

Journal ref: Journal of Instrumentation, Volume 17, August 2022: P08037

EXCESS workshop: Descriptions of rising low-energy spectra

Authors: P. Adari, A. Aguilar-Arevalo, D. Amidei, G. Angloher, E. Armengaud, C. Augier, L. Balogh, S. Banik, D. Baxter, C. Beaufort, G. Beaulieu, V. Belov, Y. Ben Gal, G. Benato, A. Benoît, A. Bento, L. Bergé, A. Bertolini, R. Bhattacharyya, J. Billard, I. M. Bloch, A. Botti, R. Breier, G. Bres, J-. L. Bret , et al. (281 additional authors not shown)

Abstract: Many low-threshold experiments observe sharply rising event rates of yet unknown origins below a few hundred eV, and larger than expected from known backgrounds. Due to the significant impact of this excess on the dark matter or neutrino sensitivity of these experiments, a collective effort has been started to share the knowledge about the individual observations. For this, the EXCESS Workshop was… ▽ More Many low-threshold experiments observe sharply rising event rates of yet unknown origins below a few hundred eV, and larger than expected from known backgrounds. Due to the significant impact of this excess on the dark matter or neutrino sensitivity of these experiments, a collective effort has been started to share the knowledge about the individual observations. For this, the EXCESS Workshop was initiated. In its first iteration in June 2021, ten rare event search collaborations contributed to this initiative via talks and discussions. The contributing collaborations were CONNIE, CRESST, DAMIC, EDELWEISS, MINER, NEWS-G, NUCLEUS, RICOCHET, SENSEI and SuperCDMS. They presented data about their observed energy spectra and known backgrounds together with details about the respective measurements. In this paper, we summarize the presented information and give a comprehensive overview of the similarities and differences between the distinct measurements. The provided data is furthermore publicly available on the workshop's data repository together with a plotting tool for visualization. △ Less

Submitted 4 March, 2022; v1 submitted 10 February, 2022; originally announced February 2022.

Comments: 44 pages, 20 figures; Editors: A. Fuss, M. Kaznacheeva, F. Reindl, F. Wagner; updated copyright statements and funding information

Journal ref: SciPost Phys. Proc. 9, 001 (2022)

Improvement of contact-less KID design using multilayered Al/Ti material for resonator

Authors: J. Colas, M. Calvo, J. Goupy, A. Monfardini, M. De Jesus, J. Billard, A. Juillard, L. Vagneron

Abstract: The necessity to increase exposure in rare event searches experiments by maintaining a low energy threshold and a good energy resolution leads to segmented detectors as in EDELWEISS (Dark Matter), CUORE (0ν\b{eta}\b{eta}) or RICOCHET (CEνNS) for example. However, the large number of sub-elements can dramatically increase the complexity of such detector arrays. In this work we report on our progres… ▽ More The necessity to increase exposure in rare event searches experiments by maintaining a low energy threshold and a good energy resolution leads to segmented detectors as in EDELWEISS (Dark Matter), CUORE (0ν\b{eta}\b{eta}) or RICOCHET (CEνNS) for example. However, the large number of sub-elements can dramatically increase the complexity of such detector arrays. In this work we report on our progress towards designing a flexible detector technology based on KID resonators evaporated on massive target crystals readout by a contact-less feed-line. Providing that we achieve O(100) eV energy threshold, such approach could easily be scaled to tens of kilogram detector arrays thanks to the intrinsic multiplexing capability of mKIDs. Using a 30 g silicon target absorber with Al/Ti multilayers for the KID resonator, we report a significant improvement of our detector response exhibiting a keV-scale energy resolution combined with the absence of position dependence on the event location. Indeed, compared to our previous work, we are now able to properly identify calibration lines from surface (20 keV X-rays) and bulk events (60 keV gamma rays). This significant improvement is an important step toward a better understanding of phonons and quasiparticles dynamics which is pivotal in optimizing this technology. △ Less

Submitted 24 November, 2021; originally announced November 2021.

Ricochet Progress and Status

Authors: Ricochet Collaboration, G. Beaulieu, V. Belov, L. Berge, J. Billard, G. Bres, J-. L. Bret, A. Broniatowski, M. Calvo, A. Cazes, D. Chaize, M. Chapellier, L. Chaplinsky, G. Chemin, R. Chen, J. Colas, M. De Jesus, P. de Marcillac, L. Dumoulin, O. Exshaw, S. Ferriol, E. Figueroa-Feliciano, J. B. Filippini, J. A. Formaggio, S. Fuard , et al. (55 additional authors not shown)

Abstract: We present an overview of recent progress towards the Ricochet coherent elastic neutrino nucleus scattering CE$ν$NS experiment. The ILL research reactor in Grenoble, France has been selected as the experiment site, after in situ studies of vibration and particle backgrounds. We present background rate estimates specific to that site, along with descriptions of the planned CryoCube and Q-Array dete… ▽ More We present an overview of recent progress towards the Ricochet coherent elastic neutrino nucleus scattering CE$ν$NS experiment. The ILL research reactor in Grenoble, France has been selected as the experiment site, after in situ studies of vibration and particle backgrounds. We present background rate estimates specific to that site, along with descriptions of the planned CryoCube and Q-Array detector payloads. △ Less

Submitted 12 November, 2021; originally announced November 2021.

Comments: Proceedings for the 19th International Workshop on Low Temperature Detectors (LTD19)

CONCERTO at APEX: installation and technical commissioning

Authors: A. Monfardini, A. Beelen, A. Benoit, J. Bounmy, M. Calvo, A. Catalano, J. Goupy, G. Lagache, P. Ade, E. Barria, M. Bethermin, O. Bourrion, G. Bres, C. De Breuck, F. -X. Desert, G. Duvauchelle, A. Fasano, T. Fenouillet, J. Garcia, G. Garde, C. Hoarau, W. Hu, J. -C. Lambert, F. Levy-Bertrand, A. Lundgren , et al. (19 additional authors not shown)

Abstract: We describe the deployment and first tests on Sky of CONCERTO, a large field-of-view (18.6arc-min) spectral-imaging instrument. The instrument operates in the range 130-310GHz from the APEX 12-meters telescope located at 5100m a.s.l. on the Chajnantor plateau. Spectra with R=1-300 are obtained using a fast (2.5Hz mechanical frequency) Fourier Transform Spectrometer (FTS), coupled to a continuous d… ▽ More We describe the deployment and first tests on Sky of CONCERTO, a large field-of-view (18.6arc-min) spectral-imaging instrument. The instrument operates in the range 130-310GHz from the APEX 12-meters telescope located at 5100m a.s.l. on the Chajnantor plateau. Spectra with R=1-300 are obtained using a fast (2.5Hz mechanical frequency) Fourier Transform Spectrometer (FTS), coupled to a continuous dilution cryostat with a base temperature of 60mK. Two 2152-pixels arrays of Lumped Element Kinetic Inductance Detectors (LEKID) are installed in the cryostat that also contains the cold optics and the front-end electronics. CONCERTO, installed in April 2021, generates more than 20k spectra per second during observations. We describe the final development phases, the installation and the first results obtained on Sky. △ Less

Submitted 26 June, 2021; originally announced June 2021.

Comments: Submitted to JLTP, Proceedings if the Low Temperature Detectors 19 conference, NIST, 2021

Understanding and minimizing resonance frequency deviations on a 4-inch kilo-pixel kinetic inductance detector array

Authors: S. Shu, M. Calvo, J. Goupy, S. Leclercq, A. Catalano, A. Bideaud, A. Monfardini, E. F. C. Driessen

Abstract: One of the advantages of kinetic inductance detectors is their intrinsic frequency domain multiplexing capability. However, fabrication imperfections usually give rise to resonance frequency deviations, which create frequency collision and limit the array yield. Here we study the resonance frequency deviation of a 4-inch kilo-pixel lumped-element kinetic inductance detector (LEKID) array using opt… ▽ More One of the advantages of kinetic inductance detectors is their intrinsic frequency domain multiplexing capability. However, fabrication imperfections usually give rise to resonance frequency deviations, which create frequency collision and limit the array yield. Here we study the resonance frequency deviation of a 4-inch kilo-pixel lumped-element kinetic inductance detector (LEKID) array using optical mapping. Using the measured resonator dimensions and film thickness, the fractional deviation can be explained within $\pm 25\times 10^{-3}$, whereas the residual deviation is due to variation of electric film properties. Using the capacitor trimming technique, the fractional deviation is decreased by a factor of 14. The yield of the trimming process is found to be 97%. The mapping yield, measured under a 110~K background, is improved from 69% to 76%, which can be further improved to 81% after updating our readout system. With the improvement in yield, the capacitor trimming technique may benefit future large-format LEKID arrays. △ Less

Submitted 30 August, 2021; v1 submitted 28 May, 2021; originally announced May 2021.

Comments: 6 pages, 7 figures, MAJOR update

Subgap kinetic inductance detector sensitive to 85-GHz radiation

Authors: F. Levy-Bertrand, A. Benoît, O. Bourrion, M. Calvo, A. Catalano, J. Goupy, F. Valenti, N. Maleeva, L. Grünhaupt, I. M. Pop, A. Monfardini

Abstract: We have fabricated an array of subgap kinetic inductance detectors (SKIDs) made of granular aluminum ($T_c\sim$2~K) sensitive in the 80-90 GHz frequency band and operating at 300~mK. We measure a noise equivalent power of $1.3\times10^{-16}$~W/Hz$^{0.5}$ on average and $2.6\times10^{-17}$~W/Hz$^{0.5}$ at best, for an illuminating power of 50~fW per pixel. Even though the circuit design of SKIDs is… ▽ More We have fabricated an array of subgap kinetic inductance detectors (SKIDs) made of granular aluminum ($T_c\sim$2~K) sensitive in the 80-90 GHz frequency band and operating at 300~mK. We measure a noise equivalent power of $1.3\times10^{-16}$~W/Hz$^{0.5}$ on average and $2.6\times10^{-17}$~W/Hz$^{0.5}$ at best, for an illuminating power of 50~fW per pixel. Even though the circuit design of SKIDs is identical to that of the kinetic inductance detectors (KIDs), the SKIDs operating principle is based on their sensitivity to subgap excitations. This detection scheme is advantageous because it avoids having to lower the operating temperature proportionally to the lowest detectable frequency. The SKIDs presented here are intrinsically selecting the 80-90 GHz frequency band, well below the superconducting spectral gap of the film, at approximately 180 GHz. △ Less

Submitted 6 April, 2021; v1 submitted 8 October, 2020; originally announced October 2020.

Comments: Suggestions and comments are welcome

Journal ref: Phys. Rev. Applied 15, 044002 (2021)

Development and application of metamaterial-based Half-Wave Plates for the NIKA and NIKA2 polarimeters

Authors: G. Pisano, A. Ritacco, A. Monfardini, C. Tucker, P. A. R. Ade, A. Shitvov, A. Benoit, M. Calvo, A. Catalano, J. Goupy, S. Leclercq, J. Macias-Perez, A. Andrianasolo, N. Ponthieu

Abstract: CONTEXT.Large field-of-view imaging/polarimetry instruments operating at millimeter and submm wavelengths are fundamental tools to understand the role of magnetic fields (MF) in channeling filament material into prestellar cores providing a unique insight in the physics of galactic star-forming regions. Among other topics, at extra-galactic scales, polarization observations of AGNs will allow us t… ▽ More CONTEXT.Large field-of-view imaging/polarimetry instruments operating at millimeter and submm wavelengths are fundamental tools to understand the role of magnetic fields (MF) in channeling filament material into prestellar cores providing a unique insight in the physics of galactic star-forming regions. Among other topics, at extra-galactic scales, polarization observations of AGNs will allow us to constrain the possible physical conditions of the emitting plasma from the jets and/or exploring the physics of dust inside supernova remnants. The kilo-pixel NIKA2 camera, installed at the IRAM 30-m telescope, represents today one of the best tools available to the astronomers to produce simultaneous intensity/polarimetry maps over large fields at 260 GHz (1.15 mm). AIMS.The polarization measurement, in NIKA and NIKA2, is achieved by rapidly modulating the total incoming polarization. This allows in the end to safely isolate the small science signal from the large, un-polarized and strongly variable, atmospheric background. METHODS.The polarization modulation is achieved by inserting a fast rotating Half-Wave Plate (HWP) in the optical beam. In order to allow wide field-of-view observations, the plate has to be large, with a diameter exceeding 250 mm. The modulation of the polarized signal, at 12 Hz, requires also the waveplate to be sufficiently light. In addition, this key optical element has to exhibit optimal electromagnetic characteristics in terms of transmission and differential phase-shift. For this purpose, three metamaterial HWPs have been developed using the mesh-filter technology. The knowledge acquired in developing the first two single-band HWPs was used to achieve the more challenging performance requirements of the last dual-band HWP. The first and the third waveplates met the requirements for both the NIKA and NIKA2 instruments. RESULTS.(abridged) △ Less

Submitted 22 June, 2020; originally announced June 2020.

Comments: Submitted to Astronomy & Astrophysics 12 pages, 28 figures

Journal ref: A&A 658, A24 (2022)

Observing with NIKA2Pol from the IRAM 30m telescope. Early results on the commissioning phase

Authors: A. Ritacco, R. Adam, P. Ade, H. Ajeddig, P. André, A. Andrianasolo, H. Aussel, A. Beelen, A. Benoît, A. Bideaud, O. Bourrion, M. Calvo, A. Catalano, B. Comis, M. De Petris, F. -X. Désert, S. Doyle, E. F. C. Driessen, A. Gomez, J. Goupy, F. Kéruzoré, C. Kramer, B. Ladjelate, G. Lagache, S. Leclercq , et al. (19 additional authors not shown)

Abstract: The NIKA2 polarization channel at 260 GHz (1.15 mm) has been proposed primarily to observe galactic star-forming regions and probe the critical scales between 0.01-0.05 pc at which magnetic field lines may channel the matter of interstellar filaments into growing dense cores. The NIKA2 polarimeter consists of a room temperature continuously rotating multi-mesh HWP and a cold polarizer that separat… ▽ More The NIKA2 polarization channel at 260 GHz (1.15 mm) has been proposed primarily to observe galactic star-forming regions and probe the critical scales between 0.01-0.05 pc at which magnetic field lines may channel the matter of interstellar filaments into growing dense cores. The NIKA2 polarimeter consists of a room temperature continuously rotating multi-mesh HWP and a cold polarizer that separates the two orthogonal polarizations onto two 260 GHz KIDs arrays. We describe in this paper the preliminary results obtained during the most recent commissioning campaign performed in December 2018. We concentrate here on the analysis of the extended sources, while the observation of compact sources is presented in a companion paper [12]. We present preliminary NIKA2 polarization maps of the Crab nebula. We find that the integrated polarization intensity flux measured by NIKA2 is consistent with expectations.In terms of polarization angle, we are still limited by systematic uncertainties that will be further investigated in the forthcoming commissioning campaigns. △ Less

Submitted 17 December, 2019; originally announced December 2019.

Comments: To appear in the proceedings of the international conference entitled mm Universe @ NIKA2, Grenoble (France), June 2019, EPJ Web of conferences

Calibration and Performance of the NIKA2 camera at the IRAM 30-meter Telescope

Authors: L. Perotto, N. Ponthieu, J. -F. Macías-Pérez, R. Adam, P. Ade, P. André, A. Andrianasolo, H. Aussel, A. Beelen, A. Benoît, S. Berta, A. Bideaud, O. Bourrion, M. Calvo, A. Catalano, B. Comis, M. De Petris, F. -X. Désert, S. Doyle, E. F. C. Driessen, P. García, A. Gomez, J. Goupy, D. John, F. Kéruzoré , et al. (23 additional authors not shown)

Abstract: NIKA2 is a dual-band millimetric continuum camera of 2900 Kinetic Inductance Detectors (KID), operating at $150$ and $260\,\rm{GHz}$, installed at the IRAM 30-meter telescope. We present the performance assessment of NIKA2 after one year of observation using a dedicated point-source calibration method, referred to as the \emph{baseline} method. Using a large data set acquired between January 2017… ▽ More NIKA2 is a dual-band millimetric continuum camera of 2900 Kinetic Inductance Detectors (KID), operating at $150$ and $260\,\rm{GHz}$, installed at the IRAM 30-meter telescope. We present the performance assessment of NIKA2 after one year of observation using a dedicated point-source calibration method, referred to as the \emph{baseline} method. Using a large data set acquired between January 2017 and February 2018 that span the whole range of observing elevations and atmospheric conditions encountered at the IRAM 30-m telescope, we test the stability of the performance parameters. We report an instantaneous field of view (FOV) of 6.5' in diameter, filled with an average fraction of $84\%$ and $90\%$ of valid detectors at $150$ and $260\,\rm{GHz}$, respectively. The beam pattern is characterized by a FWHM of $17.6'' \pm 0.1''$ and $11.1''\pm 0.2''$, and a beam efficiency of $77\% \pm 2\%$ and $55\% \pm 3\%$ at $150$ and $260\,\rm{GHz}$, respectively. The rms calibration uncertainties are about $3\%$ at $150\,\rm{GHz}$ and $6\%$ at $260\,\rm{GHz}$. The absolute calibration uncertainties are of $5\%$ and the systematic calibration uncertainties evaluated at the IRAM 30-m reference Winter observing conditions are below $1\%$ in both channels. The noise equivalent flux density (NEFD) at $150$ and $260\,\rm{GHz}$ are of $9 \pm 1\, \rm{mJy}\cdot s^{1/2}$ and $30 \pm 3\, \rm{mJy}\cdot s^{1/2}$. This state-of-the-art performance confers NIKA2 with mapping speeds of $1388 \pm 174$ and $111 \pm 11 \,\rm{arcmin}^2\cdot \rm{mJy}^{-2}\cdot \rm{h}^{-1}$ at $150$ and $260\,\rm{GHz}$. With these unique capabilities of fast dual-band mapping at high (better that 18'') angular resolution, NIKA2 is providing an unprecedented view of the millimetre Universe. △ Less

Submitted 21 January, 2020; v1 submitted 4 October, 2019; originally announced October 2019.

Comments: 37 pages, accepted for publication in A&A

Journal ref: A&A 637, A71 (2020)

Contact-less phonon detection with massive cryogenic absorbers

Authors: Johannes Goupy, Jules Colas, Martino Calvo, Julien Billard, Philippe Camus, Richard Germond, Alexandre Juillard, Lionel Vagneron, Maryvonne De Jesus, Florence Levy-Bertrand, Alessandro Monfardini

Abstract: We have developed a contact-less technique for the real time measurement of a-thermal (Cooper-pair breaking) phonons in an absorber held at sub-Kelvin temperatures. In particular, a thin-film aluminum superconducting resonator was realized on a 30-grams high-resistivity silicon crystal. The lumped-element resonator is inductively excited/read-out by a radio-frequency microstrip feed-line deposited… ▽ More We have developed a contact-less technique for the real time measurement of a-thermal (Cooper-pair breaking) phonons in an absorber held at sub-Kelvin temperatures. In particular, a thin-film aluminum superconducting resonator was realized on a 30-grams high-resistivity silicon crystal. The lumped-element resonator is inductively excited/read-out by a radio-frequency microstrip feed-line deposited on another wafer; the sensor, a Kinetic Inductance Detector (KID), is read-out without any physical contact or wiring to the absorber. The resonator demonstrates excellent electrical properties, particularly in terms of its internal quality factor. The detection of alphas and gammas in the massive absorber is achieved, with an RMS energy resolution of about 1.4 keV, which is already interesting for particle physics applications. The resolution of this prototype detector is mainly limited by the low (about 0.3%) conversion efficiency of deposited energy to superconducting excitations (quasi-particles). The demonstrated technique can be further optimized, and used to produce large arrays of a-thermal phonon detectors, for use in rare events searches such as: dark matter direct detection,neutrino-less double beta decay, or coherent elastic neutrino-nucleus scattering. △ Less

Submitted 19 November, 2019; v1 submitted 25 June, 2019; originally announced June 2019.

Comments: Accepted for publication on Applied Physics Letters

Journal ref: Appl. Phys. Lett. 115, 223506 (2019)

Increased multiplexing of superconducting microresonator arrays by post-characterization adaptation of the on-chip capacitors

Authors: Shibo Shu, Martino Calvo, Johannes Goupy, Samuel Leclercq, Andrea Catalano, Aurelien Bideaud, Alessandro Monfardini, Eduard F. C. Driessen

Abstract: We present an interdigitated capacitor trimming technique for fine-tuning the resonance frequency of superconducting microresonators and increasing the multiplexing factor. We first measure the optical response of the array with a beam mapping system to link all resonances to their physical resonators. Then a new set of resonance frequencies with uniform spacing and higher multiplexing factor is d… ▽ More We present an interdigitated capacitor trimming technique for fine-tuning the resonance frequency of superconducting microresonators and increasing the multiplexing factor. We first measure the optical response of the array with a beam mapping system to link all resonances to their physical resonators. Then a new set of resonance frequencies with uniform spacing and higher multiplexing factor is designed. We use simulations to deduce the lengths that we should trim from the capacitor fingers in order to shift the resonances to the desired frequencies. The sample is then modified using contact lithography and re-measured using the same setup. We demonstrate this technique on a 112-pixel aluminum lumped-element kinetic-inductance detector array. Before trimming, the resonance frequency deviation of this array is investigated. The variation of the inductor width plays the main role for the deviation. After trimming, the mean fractional frequency error for identified resonators is -6.4e-4, with a standard deviation of 1.8e-4. The final optical yield is increased from 70.5% to 96.7% with no observable crosstalk beyond -15 dB during mapping. This technique could be applied to other photon-sensitive superconducting microresonator arrays for increasing the yield and multiplexing factor. △ Less

Submitted 13 August, 2018; v1 submitted 11 August, 2018; originally announced August 2018.

Comments: 5 pages, 4 figures, accepted by APL

Journal ref: Appl. Phys. Lett. 113, 082603 (2018)

Tunable sub-gap radiation detection with superconducting resonators

Authors: O. Dupré, A. Benoît M. Calvo, A. Catalano, J. Goupy, C. Hoarau, T. Klein, K. Le Calvez, B. Sacépé, A. Monfardini, F. Levy-Bertrand

Abstract: We have fabricated planar amorphous Indium Oxide superconducting resonators ($T_c\sim2.8$ K) that are sensitive to frequency-selective radiation in the range of 7 to 10 GHz. Those values lay far below twice the superconducting gap that worths about 200 GHz. The photons detection consists in a shift of the fundamental resonance frequency. We show that the detected frequency can be adjusted by modul… ▽ More We have fabricated planar amorphous Indium Oxide superconducting resonators ($T_c\sim2.8$ K) that are sensitive to frequency-selective radiation in the range of 7 to 10 GHz. Those values lay far below twice the superconducting gap that worths about 200 GHz. The photons detection consists in a shift of the fundamental resonance frequency. We show that the detected frequency can be adjusted by modulating the total length of the superconducting resonator. We attribute those observations to the excitation of higher-order resonance modes. The coupling between the fundamental lumped and the higher order distributed resonance is due to the kinetic inductance non-linearity with current. These devices, that we have called Sub-gap Kinetic Inductance Detectors (SKIDs), are to be distinguished from the standard Kinetic Inductance Detectors (KIDs) in which quasi-particles are generated when incident light breaks down Cooper pairs. △ Less

Submitted 28 February, 2018; originally announced February 2018.

Comments: article: 6 pages, 4 figures supplementary: 1 page, 2 figures

Journal ref: O. Dupré et al, Supercond. Sci. Technol. 30, 04007 (2017)

Al/Ti/Al phonon-mediated KIDs for UV-VIS light detection over large areas

Authors: L. Cardani, N. Casali, A. Cruciani, H. le Sueur, M. Martinez, F. Bellini, M. Calvo, M. G. Castellano, I. Colantoni, C. Cosmelli, A. D'Addabbo, S. Di Domizio, J. Goupy, L. Minutolo, A. Monfardini, M. Vignati

Abstract: The development of wide-area cryogenic light detectors with baseline energy resolution lower than 20 eV RMS is essential for next generation bolometric experiments searching for rare interactions. Indeed the simultaneous readout of the light and heat signals will enable background suppression through particle identification. Because of their excellent intrinsic energy resolution, as well as their… ▽ More The development of wide-area cryogenic light detectors with baseline energy resolution lower than 20 eV RMS is essential for next generation bolometric experiments searching for rare interactions. Indeed the simultaneous readout of the light and heat signals will enable background suppression through particle identification. Because of their excellent intrinsic energy resolution, as well as their well-established reproducibility, Kinetic Inductance Detectors (KIDs) are good candidates for the development of next generation light detectors. The CALDER project is investigating the potential of phonon-mediated KIDs. The first phase of the project allowed to reach a baseline resolution of 80 eV using a single KID made of aluminium on a 2x2 cm\tmrsup{$2$} silicon substrate acting as photon absorber. In this paper we present a new prototype detector implementing a trilayer aluminium-titanium-aluminium KID. Taking advantage of the superconducting proximity effect the baseline resolution improves down to 26 eV. △ Less

Submitted 27 April, 2018; v1 submitted 25 January, 2018; originally announced January 2018.

Comments: submitted to SUST

Journal ref: Supercond. Sci. Technol. 31 (2018) 075002 (6pp)

Exploring Cosmic Origins with CORE: The Instrument

Authors: P. de Bernardis, P. A. R. Ade, J. J. A. Baselmans, E. S. Battistelli, A. Benoit, M. Bersanelli, A. Bideaud, M. Calvo, F. J. Casas, G. Castellano, A. Catalano, I. Charles, I. Colantoni, F. Columbro, A. Coppolecchia, M. Crook, G. D'Alessandro, M. De Petris, J. Delabrouille, S. Doyle, C. Franceschet, A. Gomez, J. Goupy, S. Hanany, M. Hills , et al. (104 additional authors not shown)

Abstract: We describe a space-borne, multi-band, multi-beam polarimeter aiming at a precise and accurate measurement of the polarization of the Cosmic Microwave Background. The instrument is optimized to be compatible with the strict budget requirements of a medium-size space mission within the Cosmic Vision Programme of the European Space Agency. The instrument has no moving parts, and uses arrays of diffr… ▽ More We describe a space-borne, multi-band, multi-beam polarimeter aiming at a precise and accurate measurement of the polarization of the Cosmic Microwave Background. The instrument is optimized to be compatible with the strict budget requirements of a medium-size space mission within the Cosmic Vision Programme of the European Space Agency. The instrument has no moving parts, and uses arrays of diffraction-limited Kinetic Inductance Detectors to cover the frequency range from 60 GHz to 600 GHz in 19 wide bands, in the focal plane of a 1.2 m aperture telescope cooled at 40 K, allowing for an accurate extraction of the CMB signal from polarized foreground emission. The projected CMB polarization survey sensitivity of this instrument, after foregrounds removal, is 1.7 μK$\cdot$arcmin. The design is robust enough to allow, if needed, a downscoped version of the instrument covering the 100 GHz to 600 GHz range with a 0.8 m aperture telescope cooled at 85 K, with a projected CMB polarization survey sensitivity of 3.2 μK$\cdot$arcmin. △ Less

Submitted 22 May, 2017; v1 submitted 5 May, 2017; originally announced May 2017.

Comments: 43 pages

Net Shape 3D Printed NdFeB Permanent Magnet

Authors: J. Jacimovic, F. Binda, L. G. Herrmann, F. Greuter, J. Genta, M. Calvo, T. Tomse, R. A. Simon

Abstract: For two decades, NdFeB based magnets have been a critical component in a range of electrical devices engaged in energy production and conversion. The magnet shape and the internal microstructure of the selected NdFeB grade govern their efficiency and size. However, stricter requirements on device efficiency call for better performing magnets preferably with novel functionality not achievable today… ▽ More For two decades, NdFeB based magnets have been a critical component in a range of electrical devices engaged in energy production and conversion. The magnet shape and the internal microstructure of the selected NdFeB grade govern their efficiency and size. However, stricter requirements on device efficiency call for better performing magnets preferably with novel functionality not achievable today. Here we use 3D metal printing by Selective Laser Melting to fabricate dense net shape permanent magnets based on NdFeB that exhibit high magnetic performance. Evidence is provided that the internal microstructure, not achievable by traditional manufacturing means, is the origin of the solid magnetic properties. The freedom in magnet body shape and size that ranges from the millimeter to tens of centimeter scale opens up a design freedom that could be a catalyzer for the next generation of electrical devices. △ Less

Submitted 15 November, 2016; originally announced November 2016.

Polarimetry at millimeter wavelengths with the NIKA camera: calibration and performance

Authors: A. Ritacco, N. Ponthieu, A. Catalano, R. Adam, P. Ade, P. André, A. Beelen, A. Benoît, A. Bideaud, N. Billot, O. Bourrion, M. Calvo, G. Coiffard, B. Comis, F. -X. Désert, S. Doyle, J. Goupy, C. Kramer, S. Leclercq, J. F. Macías-Pérez, P. Mauskopf, A. Maury, F. Mayet, A. Monfardini, F. Pajot , et al. (15 additional authors not shown)

Abstract: Magnetic fields, which play a major role in a large number of astrophysical processes from galactic to cosmological scales, can be traced via observations of dust polarization as demonstrated by the Planck satellite results. In particular, low-resolution observations of dust polarization have demonstrated that Galactic filamentary structures, where star formation takes place, are associated to wel… ▽ More Magnetic fields, which play a major role in a large number of astrophysical processes from galactic to cosmological scales, can be traced via observations of dust polarization as demonstrated by the Planck satellite results. In particular, low-resolution observations of dust polarization have demonstrated that Galactic filamentary structures, where star formation takes place, are associated to well organized magnetic fields. A better understanding of this process requires detailed observations of galactic dust polarization on scales of 0.01 to 0.1 pc. Such high-resolution polarization observations can be carried out at the IRAM 30 m telescope using the recently installed NIKA2 camera, which features two frequency bands at 260 and 150 GHz (respectively 1.15 and 2.05 mm), the 260 GHz band being polarization sensitive. NIKA2 so far in commissioning phase, has its focal plane filled with ~3300 detectors to cover a Field of View (FoV) of 6.5 arcminutes diameter. The NIKA camera, which consisted of two arrays of 132 and 224 Lumped Element Kinetic Inductance Detectors (LEKIDs) and a FWHM (Full-Width-Half-Maximum) of 12 and 18.2 arcsecond at 1.15 and 2.05 mm respectively, has been operated at the IRAM 30 m telescope from 2012 to 2015 as a test-bench for NIKA2. NIKA was equipped of a room temperature polarization system (a half wave plate (HWP) and a grid polarizer facing the NIKA cryostat window). The fast and continuous rotation of the HWP permits the quasi simultaneous reconstruction of the three Stokes parameters, I, Q and U at 150 and 260 GHz. This paper presents the first polarization measurements with KIDs and reports the polarization performance of the NIKA camera and the pertinence of the choice of the polarization setup in the perspective of NIKA2. (abridged) △ Less

Submitted 24 February, 2017; v1 submitted 7 September, 2016; originally announced September 2016.

Journal ref: A&A 599, A34 (2017)

The NIKA2 commissioning campaign: performance and first results

Authors: A. Catalano, R. Adam, P. Ade, P. André, H. Aussel, A. Beelen, A. Benoît, A. Bideaud, N. Billot, O. Bourrion, M. Calvo, G. Coiffard, B. Comis, F. -X. Désert, S. Doyle, J. Goupy, C. F. Kramer, G. Lagache, S. Leclercq, J. F. Lestrade, J. F. Macías-Pérez, A. Maury, P. Mauskopf, F. Mayet, A. Monfardini , et al. (17 additional authors not shown)

Abstract: The New IRAM KID Array 2 (NIKA 2) is a dual-band camera operating with three frequency-multiplexed kilopixels arrays of Lumped Element Kinetic Inductance Detectors (LEKID) cooled at 150 mK. NIKA 2 is designed to observe the intensity and polarisation of the sky at 1.15 and 2.0 mm wavelength from the IRAM 30 m telescope. The NIKA 2 instrument represents a huge step in performance as compared to the… ▽ More The New IRAM KID Array 2 (NIKA 2) is a dual-band camera operating with three frequency-multiplexed kilopixels arrays of Lumped Element Kinetic Inductance Detectors (LEKID) cooled at 150 mK. NIKA 2 is designed to observe the intensity and polarisation of the sky at 1.15 and 2.0 mm wavelength from the IRAM 30 m telescope. The NIKA 2 instrument represents a huge step in performance as compared to the NIKA pathfinder instrument, which has already shown state-of-the-art detector and photometric performance. After the commissioning planned to be accomplished at the end of 2016, NIKA 2 will be an IRAM resident instrument for the next ten years or more. NIKA 2 should allow the astrophysical community to tackle a large number of open questions reaching from the role of the Galactic magnetic field in star formation to the discrepancy between cluster-based and CMB-based cosmology possibly induced by the unknown cluster physics. We present an overview of the commissioning phase together with some first results. △ Less

Submitted 31 May, 2016; v1 submitted 27 May, 2016; originally announced May 2016.

Comments: 11 pages

NIKEL_AMC: Readout electronics for the NIKA2 experiment

Authors: O. Bourrion, A. Benoit, J. L. Bouly, J. Bouvier, G. Bosson, M. Calvo, A. Catalano, J. Goupy, C. Li, J. F. Macías-Pérez, A. Monfardini, D. Tourres, N. Ponchant, C. Vescovi

Abstract: The New Iram Kid Arrays-2 (NIKA2) instrument has recently been installed at the IRAM 30 m telescope. NIKA2 is a state-of-art instrument dedicated to mm-wave astronomy using microwave kinetic inductance detectors (KID) as sensors. The three arrays installed in the camera, two at 1.25 mm and one at 2.05 mm, feature a total of 3300 KIDs. To instrument these large array of detectors, a specifically de… ▽ More The New Iram Kid Arrays-2 (NIKA2) instrument has recently been installed at the IRAM 30 m telescope. NIKA2 is a state-of-art instrument dedicated to mm-wave astronomy using microwave kinetic inductance detectors (KID) as sensors. The three arrays installed in the camera, two at 1.25 mm and one at 2.05 mm, feature a total of 3300 KIDs. To instrument these large array of detectors, a specifically designed electronics, composed of 20 readout boards and hosted in three microTCA crates, has been developed. The implemented solution and the achieved performances are presented in this paper. We find that multiplexing factors of up to 400 detectors per board can be achieved with homogeneous performance across boards in real observing conditions, and a factor of more than 3 decrease in volume with respect to previous generations. △ Less

Submitted 25 October, 2016; v1 submitted 3 February, 2016; originally announced February 2016.

Comments: 21 pages; 16 figures

Journal ref: JINST 11 P11001 (2016)

CALDER: cryogenic light detector for rare events search

Authors: L. Pagnanini, E. S. Battistelli, F. Bellini, M. Calvo, L. Cardani, N. Casali, M. G. Castellano, I. Colantoni, A. Coppolecchia, C. Cosmelli, A. Cruciani, P. De Bernardis, S. Di Domizio, A. D'Addabbo, M. Martinez, S. Masi, C. Tomei, M. Vignati

Abstract: The CALDER project aims at developing cryogenic light detectors with high sensitivity to UV and visible light, to be used for particle tagging in massive bolometers. Indeed the sensitivity of CUORE can be increased by a factor of 3, thanks to the reduction of the $α$-background, obtained by detecting the Cherenkov light (100 eV) emitted by $β/γ$ events. Currently used light detectors have not the… ▽ More The CALDER project aims at developing cryogenic light detectors with high sensitivity to UV and visible light, to be used for particle tagging in massive bolometers. Indeed the sensitivity of CUORE can be increased by a factor of 3, thanks to the reduction of the $α$-background, obtained by detecting the Cherenkov light (100 eV) emitted by $β/γ$ events. Currently used light detectors have not the features required to address this task, so we decided to develop a new light detector using Kinetic Inductance Detector as a sensor. This approach is very challenging and requires an intensive R$\&$D to be satisfied. The first results of this activity are shown in the following. △ Less

Submitted 30 December, 2015; originally announced December 2015.

Comments: XVI International Workshop on Neutrino Telescopes, Venice. in PoS(NEUTEL2015)076

Journal ref: PoS (NEUTEL 2015) 076

Uniform non-stoichiometric titanium nitride thin films for improved kinetic inductance detector array

Authors: G. Coiffard, K-F. Schuster, E. F. C. Driessen, S. Pignard, M. Calvo, A. Catalano, J. Goupy, A. Monfardini

Abstract: We describe the fabrication of homogeneous sub-stoichiometric titanium nitride films for microwave kinetic inductance detector (mKID) arrays. Using a 6 inch sputtering target and a homogeneous nitrogen inlet, the variation of the critical temperature over a 2 inch wafer was reduced to <25 %. Measurements of a 132-pixel mKID array from these films reveal a sensitivity of 16 kHz/pW in the 100 GHz ba… ▽ More We describe the fabrication of homogeneous sub-stoichiometric titanium nitride films for microwave kinetic inductance detector (mKID) arrays. Using a 6 inch sputtering target and a homogeneous nitrogen inlet, the variation of the critical temperature over a 2 inch wafer was reduced to <25 %. Measurements of a 132-pixel mKID array from these films reveal a sensitivity of 16 kHz/pW in the 100 GHz band, comparable to the best aluminium mKIDs. We measured a noise equivalent power of NEP = 3.6e-15 W/Hz^(1/2). Finally, we describe possible routes to further improve the performance of these TiN mKID arrays. △ Less

Submitted 7 January, 2016; v1 submitted 7 October, 2015; originally announced October 2015.

Comments: 7 pages, 4 figures, submitted to Journal of low temperature physics, Proceedings of LTD-16

High-energy interactions in Kinetic Inductance Detectors arrays

Authors: A. D'Addabbo, M. Calvo, J. Goupy, A. Benoit, O. Bourrion, A. Catalano, J. F. Macias-Perez, A. Monfardini

Abstract: The impacts of Cosmic Rays on the detectors are a key problem for space-based missions. We are studying the effects of such interactions on arrays of Kinetic Inductance Detectors (KID), in order to adapt this technology for use on board of satellites. Before proposing a new technology such as the Kinetic Inductance Detectors for a space-based mission, the problem of the Cosmic Rays that hit the de… ▽ More The impacts of Cosmic Rays on the detectors are a key problem for space-based missions. We are studying the effects of such interactions on arrays of Kinetic Inductance Detectors (KID), in order to adapt this technology for use on board of satellites. Before proposing a new technology such as the Kinetic Inductance Detectors for a space-based mission, the problem of the Cosmic Rays that hit the detectors during in-flight operation has to be studied in detail. We present here several tests carried out with KID exposed to radioactive sources, which we use to reproduce the physical interactions induced by primary Cosmic Rays, and we report the results obtained adopting different solutions in terms of substrate materials and array geometries. We conclude by outlining the main guidelines to follow for fabricating KID for space-based applications. △ Less

Submitted 7 May, 2015; originally announced May 2015.

Journal ref: Proc. of SPIE 2014, Vol. 9153 91532Q-1

CALDER - Neutrinoless double-beta decay identification in TeO$_2$ bolometers with kinetic inductance detectors

Authors: E. S. Battistelli, F. Bellini, C. Bucci, M. Calvo, L. Cardani, N. Casali, M. G. Castellano, I. Colantoni, A Coppolecchia, C. Cosmelli, A. Cruciani, P. de Bernardis, S. Di Domizio, A. D'Addabbo, M. Martinez, S. Masi, L. Pagnanini, C. Tomei, M. Vignati

Abstract: 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 $α$ radioactivity. This is possible if, i… ▽ More 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 $α$ radioactivity. This is possible if, in coincidence with the heat release in a bolometer, the Cherenkov light emitted by the $β$ 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. △ Less

Submitted 19 May, 2015; v1 submitted 6 May, 2015; originally announced May 2015.

Comments: 8 pages, 3 figures, added reference to first results

Journal ref: Eur.Phys.J. C75 (2015) 8, 353

Kinetic inductance detectors for millimeter and submillimeter astronomy / Détecteurs à inductance cinétique pour l'astronomie millimétrique et sub-millimétrique

Authors: Nicolas Boudou, Alain Benoit, Olivier Bourrion, Martino Calvo, François-Xavier Désert, Juan Macias-Perez, Alessandro Monfardini, Markus Roesch

Abstract: We present recent developments in Kinetic Inductance Detectors (KID) for large arrays of detectors. The main application is ground-based millimeter wave astronomy. We focus in particular, as a case study, on our own experiment: NIKA (Néel IRAM KID Arrays). NIKA is today the best in-the-field experiment using KID-based instruments, and consists of a dual-band imaging system designed for the IRAM 30… ▽ More We present recent developments in Kinetic Inductance Detectors (KID) for large arrays of detectors. The main application is ground-based millimeter wave astronomy. We focus in particular, as a case study, on our own experiment: NIKA (Néel IRAM KID Arrays). NIKA is today the best in-the-field experiment using KID-based instruments, and consists of a dual-band imaging system designed for the IRAM 30 meter telescope at Pico Veleta. We describe in this article, after a general context introduction, the KID working principle and the readout electronics, crucial to take advantage of the intrinsic KID multiplexability. We conclude with a small subset of the astronomical sources observed simultaneously at 2 mm and 1.4 mm by NIKA during the last run, held in October 2010. Nous décrivons les récents développements concernant les grandes matrices de détecteurs à inductance cinétique (KID) dont l'application principale est l'astronomie millimétrique au sol. Nous détaillons en particulier notre propre caméra : NIKA (Néel IRAM KID Arrays) qui est aujourd'hui l'instrument le plus abouti mettant en oeuvre des KIDs. NIKA est une caméra bi-bande conçue pour le radiotélescope de 30 mètres de l'IRAM à Pico Veleta. Aprés avoir décrit le contexte instrumental dans lequel ils s'inscrivent, nous expliquerons le principe de fonctionnement des KIDs et de leur électronique de lecture, cruciale pour pouvoir tirer parti de leur potentiel de muliplexage. Pour finir, nous présentons quelques exemples d'observations effectuées par NIKA dans les bandes de 2 mm et 1,4 mm au cours de la dernière campagne d'observation en octobre 2010. △ Less

Submitted 27 January, 2012; v1 submitted 26 January, 2012; originally announced January 2012.

Comments: Withdrawn, will be resubmitted with a new list of authors

Journal ref: Comptes Rendus Physique 13, 62-70 (2012)

A dual-band millimeter-wave kinetic inductance camera for the IRAM 30-meter telescope

Authors: A. Monfardini, A. Benoit, A. Bideaud, L. J. Swenson, M. Roesch, F. X. Desert, S. Doyle, A. Endo, A. Cruciani, P. Ade, A. M. Baryshev, J. J. A. Baselmans, O. Bourrion, M. Calvo, P. Camus, L. Ferrari, C. Giordano, C. Hoffmann, S. Leclercq, J. F. Macias-Perez, P. Mauskopf, K. F. Schuster, C. Tucker, C. Vescovi, S. J. C. Yates

Abstract: Context. The Neel IRAM KIDs Array (NIKA) is a fully-integrated measurement system based on kinetic inductance detectors (KIDs) currently being developed for millimeter wave astronomy. In a first technical run, NIKA was successfully tested in 2009 at the Institute for Millimetric Radio Astronomy (IRAM) 30-meter telescope at Pico Veleta, Spain. This prototype consisted of a 27-42 pixel camera imagin… ▽ More Context. The Neel IRAM KIDs Array (NIKA) is a fully-integrated measurement system based on kinetic inductance detectors (KIDs) currently being developed for millimeter wave astronomy. In a first technical run, NIKA was successfully tested in 2009 at the Institute for Millimetric Radio Astronomy (IRAM) 30-meter telescope at Pico Veleta, Spain. This prototype consisted of a 27-42 pixel camera imaging at 150 GHz. Subsequently, an improved system has been developed and tested in October 2010 at the Pico Veleta telescope. The instrument upgrades included dual-band optics allowing simultaneous imaging at 150 GHz and 220 GHz, faster sampling electronics enabling synchronous measurement of up to 112 pixels per measurement band, improved single-pixel sensitivity, and the fabrication of a sky simulator to replicate conditions present at the telescope. Results. The new dual-band NIKA was successfully tested in October 2010, performing in-line with sky simulator predictions. Initially the sources targeted during the 2009 run were re-imaged, verifying the improved system performance. An optical NEP was then calculated to be around 2 \dot 10-16 W/Hz1/2. This improvement in comparison with the 2009 run verifies that NIKA is approaching the target sensitivity for photon-noise limited ground-based detectors. Taking advantage of the larger arrays and increased sensitivity, a number of scientifically-relevant faint and extended objects were then imaged including the Galactic Center SgrB2(FIR1), the radio galaxy Cygnus A and the NGC1068 Seyfert galaxy. These targets were all observed simultaneously in the 150 GHz and 220 GHz atmospheric windows. △ Less

Submitted 8 February, 2011; v1 submitted 4 February, 2011; originally announced February 2011.

Comments: Submitted to ApJ (abstract reduced to fit ApJ standards)

Journal ref: The Astrophysical Journal Supplement Series, Volume 194, Number 2, 24 (2011)