arXiv subjects

A. Tartari

Publications and source records attributed to A. Tartari.

At least 19 recordsLinked to original sources

arXiv2026

Background of the BULLKID detector array operated with moderate shield on surface

We present the operation with moderate radiation shield in a surface laboratory of BULLKID (BULky and Low-threshold Kinetic Inductance Detector), a cryogenic detector for searches of light Dark Matter or Coherent 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 analysis presented focuses on data from 15 elements of the array, with two central units used to evaluate the background and with their surrounding elements used as veto. The low energy spectrum resulting from an exposure of 290 hours to ambient backgrounds, acquired with the use of external and internal radiation shields, is compatible with the simulations at the level of $(6.8\pm0.4\,{\rm stat.}\pm0.1\,{\rm syst.})\times10^4$ counts / keV kg days from 2 keV down to an energy of 600 eV. The region between 225 eV and 600 eV shows a rise in background in disagreement with the simulations, while not sharing some of the key traits of the low energy excess observed in other cryogenic experiments. The high energy spectrum shape is in overall agreement with the simulations and displays the typical particle-induced X-ray emission of the surrounding lead.

hep-ex↗

arXiv2026

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

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.

physics.ins-det↗

arXiv2025

TES Proton Irradiation Result Analysis for Future Space Applications

As observed on the signal of the Planck-HFI highly sensitive bolometers, the effect of cosmic rays on detectors is a major concern for future similar space missions. Their instruments will have a larger detection surface, increased sensitivity, and more stringent requirements on the suppression of systematic effects. To study the impact of cosmic rays on detector prototypes in operational conditions, IAS has designed a state-of-the-art cryogenic system to irradiate particles by coupling this facility to particle accelerators. An irradiation campaign has been carried out on LiteBIRD-HFT TES prototypes to study their response to particle hits. In this article, we present the results and the analysis of this first test campaign.

physics.ins-det↗

arXiv2025

Energy calibration of bulk events in the BULLKID detector

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.

physics.ins-det↗

arXiv2025

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

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.

physics.ins-det↗

arXiv2024

LiteBIRD Science Goals and Forecasts: Primordial Magnetic Fields

We present detailed forecasts for the constraints on primordial magnetic fields (PMFs) that will be obtained with the LiteBIRD satellite. The constraints are driven by the effects of PMFs on the CMB anisotropies: the gravitational effects of magnetically-induced perturbations; the effects on the thermal and ionization history of the Universe; the Faraday rotation imprint on the CMB polarization; and the non-Gaussianities induced in polarization anisotropies. LiteBIRD represents a sensitive probe for PMFs and by exploiting all the physical effects, it will be able to improve the current limit coming from Planck. In particular, thanks to its accurate $B$-mode polarization measurement, LiteBIRD will improve the constraints on infrared configurations for the gravitational effect, giving $B_{\rm 1\,Mpc}^{n_{\rm B} =-2.9} < 0.8$ nG at 95% C.L., potentially opening the possibility to detect nanogauss fields with high significance. We also observe a significant improvement in the limits when marginalized over the spectral index, $B_{1\,{\rm Mpc}}^{\rm marg}< 2.2$ nG at 95% C.L. From the thermal history effect, which relies mainly on $E$-mode polarization data, we obtain a significant improvement for all PMF configurations, with the marginalized case, $\sqrt{\langle B^2\rangle}^{\rm marg}<0.50$ nG at 95% C.L. Faraday rotation constraints will take advantage of the wide frequency coverage of LiteBIRD and the high sensitivity in $B$ modes, improving the limits by orders of magnitude with respect to current results, $B_{1\,{\rm Mpc}}^{n_{\rm B} =-2.9} < 3.2$ nG at 95% C.L. Finally, non-Gaussianities of the $B$-mode polarization can probe PMFs at the level of 1 nG, again significantly improving the current bounds from Planck. Altogether our forecasts represent a broad collection of complementary probes, providing conservative limits on PMF characteristics that will be achieved with LiteBIRD.

astro-ph.CO↗

arXiv2022

Polarization angle requirements for CMB B-mode experiments. Application to the LiteBIRD satellite

A methodology to provide the polarization angle requirements for different sets of detectors, at a given frequency of a CMB polarization experiment, is presented. The uncertainties in the polarization angle of each detector set are related to a given bias on the tensor-to-scalar ratio $r$ parameter. The approach is grounded in using a linear combination of the detector sets to obtain the CMB polarization signal. In addition, assuming that the uncertainties on the polarization angle are in the small angle limit (lower than a few degrees), it is possible to derive analytic expressions to establish the requirements. The methodology also accounts for possible correlations among detectors, that may originate from the optics, wafers, etc. The approach is applied to the LiteBIRD space mission. We show that, for the most restrictive case (i.e., full correlation of the polarization angle systematics among detector sets), the requirements on the polarization angle uncertainties are of around 1 arcmin at the most sensitive frequency bands (i.e., $\approx 150$ GHz) and of few tens of arcmin at the lowest (i.e., $\approx 40$ GHz) and highest (i.e., $\approx 400$ GHz) observational bands. Conversely, for the least restrictive case (i.e., no correlation of the polarization angle systematics among detector sets), the requirements are $\approx 5$ times less restrictive than for the previous scenario. At the global and the telescope levels, polarization angle knowledge of a few arcmins is sufficient for correlated global systematic errors and can be relaxed by a factor of two for fully uncorrelated errors in detector polarization angle. The reported uncertainty levels are needed in order to have the bias on $r$ due to systematics below the limit established by the LiteBIRD collaboration.

astro-ph.CO↗

arXiv2022

QUBIC VII: The feedhorn-switch system of the technological demonstrator

We present the design, manufacturing and performance of the horn-switch system developed for the technological demonstrator of QUBIC (the $Q$\&$U$ Bolometric Interferometer for Cosmology). This system is constituted of 64 back-to-back dual-band (150\,GHz and 220\,GHz) corrugated feed-horns interspersed with mechanical switches used to select desired baselines during the instrument self-calibration. We manufactured the horns in aluminum platelets milled by photo-chemical etching and mechanically tightened with screws. The switches are based on steel blades that open and close the wave-guide between the back-to-back horns and are operated by miniaturized electromagnets. We also show the current development status of the feedhorn-switch system for the QUBIC full instrument, based on an array of 400 horn-switch assemblies.

astro-ph.IM↗

arXiv2022

QUBIC II: Spectro-Polarimetry with Bolometric Interferometry

Bolometric interferometry is a novel technique that has the ability to perform spectral imaging. A bolometric interferometer observes the sky in a wide frequency band and can reconstruct sky maps in several sub-bands within the physical band in post-processing of the data. This provides a powerful spectral method to discriminate between the cosmic microwave background (CMB) and astrophysical foregrounds. In this paper, the methodology is illustrated with examples based on the Q \& U Bolometric Interferometer for Cosmology (QUBIC) which is a ground-based instrument designed to measure the B-mode polarization of the sky at millimeter wavelengths. We consider the specific cases of point source reconstruction and Galactic dust mapping and we characterize the point spread function as a function of frequency. We study the noise properties of spectral imaging, especially the correlations between sub-bands, using end-to-end simulations together with a fast noise simulator. We conclude showing that spectral imaging performance are nearly optimal up to five sub-bands in the case of QUBIC.

astro-ph.IM↗

arXiv2022

QUBIC III: Laboratory Characterization

A prototype version of the Q & U Bolometric Interferometer for Cosmology (QUBIC) underwent a campaign of testing in the laboratory at Astroparticle Physics and Cosmology in Paris. We report the results of this Technological Demonstrator which successfully shows the feasibility of the principle of Bolometric Interferometry. Characterization of QUBIC includes the measurement of the synthesized beam, the measurement of interference fringes, and the measurement of polarization performance. A modulated and frequency tunable millimetre-wave source in the telescope far-field is used to simulate a point source. The QUBIC pointing is scanned across the point source to produce beam maps. Polarization modulation is measured using a rotating Half Wave Plate. The measured beam matches well to the theoretical simulations and gives QUBIC the ability to do spectro imaging. The polarization performance is excellent with less than 0.5\% cross-polarization rejection. QUBIC is ready for deployment on the high altitude site at Alto Chorillo, Argentina to begin scientific operations.

astro-ph.IM↗

arXiv2021

BISOU: a balloon project to measure the CMB spectral distortions

The BISOU (Balloon Interferometer for Spectral Observations of the Universe) project aims to study the viability and prospects of a balloon-borne spectrometer, pathfinder of a future space mission dedicated to the measurements of the CMB spectral distortions. We present here a preliminary concept based on previous space mission proposals, together with some sensitivity calculation results for the observation goals, showing that a 5-sigma measurement of the y-distortions is achievable.

astro-ph.IM↗

arXiv2021

QUBIC IV: Performance of TES Bolometers and Readout Electronics

A prototype version of the Q & U bolometric interferometer for cosmology (QUBIC) underwent a campaign of testing in the laboratory at Astroparticle Physics and Cosmology laboratory in Paris (APC). The detection chain is currently made of 256 NbSi transition edge sensors (TES) cooled to 320 mK. The readout system is a 128:1 time domain multiplexing scheme based on 128 SQUIDs cooled at 1 K that are controlled and amplified by an SiGe application specific integrated circuit at 40 K. We report the performance of this readout chain and the characterization of the TES. The readout system has been functionally tested and characterized in the lab and in QUBIC. The low noise amplifier demonstrated a white noise level of 0.3 nV.Hz^-0.5. Characterizations of the QUBIC detectors and readout electronics includes the measurement of I-V curves, time constant and the noise equivalent power. The QUBIC TES bolometer array has approximately 80% detectors within operational parameters. It demonstrated a thermal decoupling compatible with a phonon noise of about 5.10^-17 W.Hz^-0.5 at 410 mK critical temperature. While still limited by microphonics from the pulse tubes and noise aliasing from readout system, the instrument noise equivalent power is about 2.10^-16 W.Hz^-0.5, enough for the demonstration of bolometric interferometry.

astro-ph.IM↗

arXiv2021

QUBIC I: Overview and ScienceProgram

The Q $\&$ U Bolometric Interferometer for Cosmology (QUBIC) is a novel kind of polarimeter optimized for the measurement of the B-mode polarization of the Cosmic Microwave Background (CMB), which is one of the major challenges of observational cosmology. The signal is expected to be of the order of a few tens of nK, prone to instrumental systematic effects and polluted by various astrophysical foregrounds which can only be controlled through multichroic observations. QUBIC is designed to address these observational issues with a novel approach that combines the advantages of interferometry in terms of control of instrumental systematic effects with those of bolometric detectors in terms of wide-band, background-limited sensitivity. The QUBIC synthesized beam has a frequency-dependent shape that results in the ability to produce maps of the CMB polarization in multiple sub-bands within the two physical bands of the instrument (150 and 220 GHz). These features make QUBIC complementary to other instruments and makes it particularly well suited to characterize and remove Galactic foreground contamination. In this article, first of a series of eight, we give an overview of the QUBIC instrument design, the main results of the calibration campaign, and present the scientific program of QUBIC including not only the measurement of primordial B-modes, but also the measurement of Galactic foregrounds. We give forecasts for typical observations and measurements: with three years of integration on the sky and assuming perfect foreground removal as well as stable atmospheric conditions from our site in Argentina, our simulations show that we can achieve a statistical sensitivity to the effective tensor-to-scalar ratio (including primordial and foreground B-modes) $σ(r)=0.015$.

astro-ph.IM↗

arXiv2021

QUBIC V: Cryogenic system design and performance

Current experiments aimed at measuring the polarization of the Cosmic Microwave Background (CMB) use cryogenic detector arrays and cold optical systems to boost the mapping speed of the sky survey. For these reasons, large volume cryogenic systems, with large optical windows, working continuously for years, are needed. Here we report on the cryogenic system of the QUBIC (Q and U Bolometric Interferometer for Cosmology) experiment: we describe its design, fabrication, experimental optimization and validation in the Technological Demonstrator configuration. The QUBIC cryogenic system is based on a large volume cryostat, using two pulse-tube refrigerators to cool at ~3K a large (~1 m^3) volume, heavy (~165kg) instrument, including the cryogenic polarization modulator, the corrugated feedhorns array, and the lower temperature stages; a 4He evaporator cooling at ~1K the interferometer beam combiner; a 3He evaporator cooling at ~0.3K the focal-plane detector arrays. The cryogenic system has been tested and validated for more than 6 months of continuous operation. The detector arrays have reached a stable operating temperature of 0.33K, while the polarization modulator has been operated from a ~10K base temperature. The system has been tilted to cover the boresight elevation range 20 deg -90 deg without significant temperature variations. The instrument is now ready for deployment to the high Argentinean Andes.

astro-ph.IM↗

arXiv2021

QUBIC VIII: Optical design and performance

The Q and U Bolometric Interferometer for Cosmology (QUBIC) is a ground-based experiment that aims to detect B-mode polarisation anisotropies in the CMB at angular scales around the l=100 recombination peak. Systematic errors make ground-based observations of B modes at millimetre wavelengths very challenging and QUBIC mitigates these problems in a somewhat complementary way to other existing or planned experiments using the novel technique of bolometric interferometry. This technique takes advantage of the sensitivity of an imager and the systematic error control of an interferometer. A cold reflective optical combiner superimposes there-emitted beams from 400 aperture feedhorns on two focal planes. A shielding system composedof a fixed groundshield, and a forebaffle that moves with the instrument, limits the impact of local contaminants. The modelling, design, manufacturing and preliminary measurements of the optical components are described in this paper.

astro-ph.IM↗

arXiv2021

The large scale polarization explorer (LSPE) for CMB measurements: performance forecast

[Abridged] The measurement of the polarization of the Cosmic Microwave Background radiation is one of the current frontiers in cosmology. In particular, the detection of the primordial B-modes, could reveal the presence of gravitational waves in the early Universe. The detection of such component is at the moment the most promising technique to probe the inflationary theory describing the very early evolution of the Universe. We present the updated performance forecast of the Large Scale Polarization Explorer (LSPE), a program dedicated to the measurement of the CMB polarization. LSPE is composed of two instruments: Strip, a radiometer-based telescope on the ground in Tenerife, and SWIPE (Short-Wavelength Instrument for the Polarization Explorer) a bolometer-based instrument designed to fly on a winter arctic stratospheric long-duration balloon. The program is among the few dedicated to observation of the Northern Hemisphere, while most of the international effort is focused into ground-based observation in the Southern Hemisphere. Measurements are currently scheduled in Winter 2021/22 for SWIPE, with a flight duration up to 15 days, and in Summer 2021 with two years observations for Strip. We describe the main features of the two instruments, identifying the most critical aspects of the design, in terms of impact into performance forecast. We estimate the expected sensitivity of each instrument and propagate their combined observing power to the sensitivity to cosmological parameters, including the effect of scanning strategy, component separation, residual foregrounds and partial sky coverage. We also set requirements on the control of the most critical systematic effects and describe techniques to mitigate their impact. LSPE can reach a sensitivity in tensor-to-scalar ratio of $σ_r<0.01$, and improve constrains on other cosmological parameters.

astro-ph.IM↗

arXiv2020

QUBIC VI: cryogenic half wave plate rotator, design and performances

Inflation Gravity Waves B-Modes polarization detection is the ultimate goal of modern large angular scale cosmic microwave background (CMB) experiments around the world. A big effort is undergoing with the deployment of many ground-based, balloon-borne and satellite experiments using different methods to separate this faint polarized component from the incoming radiation. One of the largely used technique is the Stokes Polarimetry that uses a rotating half-wave plate (HWP) and a linear polarizer to separate and modulate the polarization components with low residual cross-polarization. This paper describes the QUBIC Stokes Polarimeter highlighting its design features and its performances. A common systematic with these devices is the generation of large spurious signals synchronous with the rotation and proportional to the emissivity of the optical elements. A key feature of the QUBIC Stokes Polarimeter is to operate at cryogenic temperature in order to minimize this unwanted component. Moving efficiently this large optical element at low temperature constitutes a big engineering challenge in order to reduce friction power dissipation. Big attention has been given during the designing phase to minimize the differential thermal contractions between parts. The rotation is driven by a stepper motor placed outside the cryostat to avoid thermal load dissipation at cryogenic temperature. The tests and the results presented in this work show that the QUBIC polarimeter can easily achieve a precision below 0.1° in positioning simply using the stepper motor precision and the optical absolute encoder. The rotation induces only few mK of extra power load on the second cryogenic stage (~ 8 K).

astro-ph.IM↗

arXiv2020

Progress report on the Large Scale Polarization Explorer

The Large Scale Polarization Explorer (LSPE) is a cosmology program for the measurement of large scale curl-like features (B-modes) in the polarization of the Cosmic Microwave Background. Its goal is to constrain the background of inflationary gravity waves traveling through the universe at the time of matter-radiation decoupling. The two instruments of LSPE are meant to synergically operate by covering a large portion of the northern microwave sky. LSPE/STRIP is a coherent array of receivers planned to be operated from the Teide Observatory in Tenerife, for the control and characterization of the low-frequency polarized signals of galactic origin; LSPE/SWIPE is a balloon-borne bolometric polarimeter based on 330 large throughput multi-moded detectors, designed to measure the CMB polarization at 150 GHz and to monitor the polarized emission by galactic dust above 200 GHz. The combined performance and the expected level of systematics mitigation will allow LSPE to constrain primordial B-modes down to a tensor/scalar ratio of $10^{-2}$. We here report the status of the STRIP pre-commissioning phase and the progress in the characterization of the key subsystems of the SWIPE payload (namely the cryogenic polarization modulation unit and the multi-moded TES pixels) prior to receiver integration.

astro-ph.IM↗