arXiv subjects

Giuseppe Di Carlo

Publications and source records attributed to Giuseppe Di Carlo.

At least 19 recordsLinked to original sources

arXiv2026

RadioAxion results on the search for axion dark matter under Gran Sasso

We report first results from RadioAxion, an underground experiment searching for axion dark matter through periodic modulations of radioisotope decays. We monitor the $α$ decay of ${^{241}}$Am via its $59.5$ keV $γ$ line using a NaI detector installed at the Gran Sasso Laboratory, where cosmic-ray-induced systematics are strongly suppressed. We present the measured spectra and the corresponding time-series analysis. No evidence for a periodic modulation is observed. From these data we derive constraints on the axion decay constant in the axion mass range from $10^{-21}$ to $10^{-9}$ eV.

hep-ex↗

arXiv2026

Weak nuclear decays deep-underground as a probe of axion dark matter

We investigate the time modulation of weak nuclear decays as a method to probe axion dark matter. To this end, we develop a theoretical framework to compute the $θ$-dependence of weak nuclear decays, including electron capture and $β$ decay, which enables us to predict the time variation of weak radioactivity in response to an oscillating axion dark matter background. As an application, we recast old data sets, from the weak nuclear decays of ${^{40}\text{K}}$ and ${^{137}\text{Cs}}$ taken at the underground Gran Sasso Laboratory, in order to set constraints on the axion decay constant, specifically in the axion mass range from few $10^{-23}\;$eV up to $10^{-19}\;$eV. We finally propose a new measurement at the Gran Sasso Laboratory, based on the weak nuclear decay of ${^{40}\text{K}}$ via electron capture, in order to explore even shorter timescales, thus reaching sensitivities to axion masses up to $10^{-9}\;$eV.

hep-ph↗

arXiv2026

High-precision measurement of $^{215}$Po half-life via delayed-coincidence analysis

We performed a high-precision study of the $^{215}$ Po $α$-decay using a LaBr$_3$ scintillating detector in a low-background environment. The $^{227}$Ac intrinsic contamination in the LaBr$_3$ crystal undergoes a decay chain, producing the intermediate pair of $^{219}$Rn$\rightarrow^{215}$Po$\rightarrow^{211}$Pb decays. The fast time response and good energy resolution of the detector allow for extracting the short half-life of $^{215}$Po from the time correlation of the two subsequent $α$-decays by using the delayed coincidence method. Thanks to high statistics and a comprehensive uncertainty assessment, we obtain the most precise half-life value to date of $^{215}$Po, corresponding to $1.77804\pm0.00091$(stat.)$\pm0.00067$(syst.) ms.

nucl-ex↗

arXiv2025

ASTAROTH: A Novel Detector for Dark Matter Direct Detection Using Cryogenic SiPMs

The DAMA experiment's long-standing claim of dark matter detection remains a key open issue in astroparticle physics. Independent verification requires NaI(Tl)-based detectors with enhanced low-energy sensitivity. Current detectors rely on photomultiplier tubes (PMTs) which features limited detection efficiency, intrinsic radioactivity, and high noise at keV energies. ASTAROTH is an R&D project that developed a proof of concept NaI(Tl) detector where siliconphotomultipliers (SiPMs) have been used instead of PMTs, offering higher photon detection efficiency, negligible radioactivity, and, most of all, a reduction of two orders of magnitude in the dark noise. The setup includes a custom cryostat operating at approximately 80 K. We report the first characterization of an approximately 360 g NaI(Tl) crystal coupled to a 5 x 5 cm SiPM matrix, yielding 4.5 photoelectrons\keV after crosstalk correction. This promising result demonstrates the feasibility of SiPM-based readout for NaI(Tl) and paves the way for future large-scale dark matter experiments.

physics.ins-det↗

arXiv2025

Probing a Light Scalar Boson with a few-MeV Proton Beam Deep Underground

We propose to investigate the production of a light scalar boson $ϕ$ in low-energy proton-nucleus interactions using the 3.5 MV accelerator of the Bellotti Ion Beam Facility, located in the underground Gran Sasso National Laboratory. Nuclear reactions induced by a few-MeV proton beam on suitable target materials can act as a controlled source of $ϕ$ particles. Owing to the deep-underground location, the facility benefits from substantial cosmic-ray shielding, enabling searches for rare processes with minimal background. The produced $ϕ$ particles will be sought with large-volume, low-background detectors already operating or currently under construction at the Gran Sasso National Laboratory. This approach combines a tunable accelerator-based production mechanism with the exceptional sensitivity of underground rare-event searches, offering a novel avenue to probe light scalar bosons beyond the Standard Model.

hep-ph↗

arXiv2025

Characterization of a GAGG detector for neutron measurements in underground laboratories

In rare events experiments, such as those devoted to the direct search of dark matter, a precise knowledge of the environmental gamma and neutron backgrounds is crucial for reaching the design experiment sensitivity. The neutron component is often poorly known due to the lack of a scalable detector technology for the precise measurement of low-flux neutron spectra. Gd$_3$Al$_2$Ga$_3$O$_{12}$ (GAGG) is a newly developed, high-density scintillating crystal with a high gadolinium content, which could allow to exploit the high $(n,γ)$ cross section of $^{155}$Gd and $^{157}$Gd for neutron measurements in underground environments. GAGG crystals feature a high scintillation light yield, good timing performance, and the capability of particle identification via pulse-shape discrimination. In a low-background environment, the distinctive signature produced by neutron capture on gadolinium, namely a $β/γ$ cascade releasing up to 9 MeV of total energy, and the efficient particle identification provided by GAGG could yield a background-free neutron capture signal. In this work, we present the characterization of a first GAGG detector prototype in terms of particle discrimination performance, intrinsic radioactive contamination, and neutron response.

physics.ins-det↗

arXiv2024

Alpha radioactivity deep-underground as a probe of axion dark matter

We propose to investigate the time modulation of radioisotope decays deep underground as a method to explore axion dark matter. In this work, we focus on the $α$-decay of heavy isotopes and develop a theoretical description for the $θ$-dependence of $α$-decay half-lives, which enables us to predict the time variation of $α$-radioactivity in response to an oscillating axion dark matter background. To probe this scenario, we have recently constructed and installed a setup deep underground at the Gran Sasso Laboratory, based on the $α$-decay of Americium-241. This prototype experiment, named RadioAxion-$α$, will allow us to explore a broad range of oscillation's periods, from a micro-second up to one year, thus providing competitive limits on the axion decay constant across 13 orders of magnitude in the axion mass, ranging from $10^{-9}$ eV to $10^{-20}$ eV after one month of data collection, and down to $10^{-22}$ eV after three years.

hep-ph↗

arXiv2022

The ASTAROTH project

The most discussed topic in direct search for dark matter is arguably the verification of the DAMA claim. In fact, the observed annual modulation of the signal rate in an array of NaI(Tl) detectors can be interpreted as the awaited signature of dark matter interaction. Several experimental groups are currently engaged in the attempt to verify such a game-changing claim with the same target material. However, all present-day designs are based on a light readout via Photomultiplier Tubes, whose high noise makes it challenging to achieve a low background in the 1-6 keV energy region of the signal. Even harder it would be to break below 1 keV energy threshold, where a large fraction of the signal potentially awaits to be uncovered. ASTAROTH is an R\&D project to overcome these limitations by using Silicon Photomultipliers (SiPM) matrices to collect scintillation light from NaI(Tl). The all-active design based on cubic crystals is operating in the 87-150 K temperature range where SiPM noise can be even a hundred times lower with respect to PMTs. The cryostat was developed following an innovative design and is based on a copper chamber immersed in a liquid argon bath that can be instrumented as a veto detector. We have characterized separately the crystal and the SiPM response at low temperature and we have proceeded to the first operation of a NaI(Tl) crystal read by SiPM in cryogeny.

physics.ins-det↗

arXiv2017

Massive Schwinger model at finite $θ$

Using the approach developed in [V. Azcoiti, G. Di Carlo, A. Galante, V. Laliena, \textit{Phys. Lett.} \textbf{B563}, (2003) 117], we are able to reconstruct the behavior of the massive 1-flavor Schwinger model with a $θ$ term and a quantized topological charge. We calculate the full dependence of the order parameter with $θ$. Our results at $θ= π$ are compatible with Coleman's conjecture on the phase diagram of this model.

hep-lat↗

arXiv2017

Antiferromagnetic Ising model in an imaginary magnetic field

We study the two-dimensional antiferromagnetic Ising model with a purely imaginary magnetic field, which can be thought of as a toy model for the usual $θ$ physics. Our motivation is to have a benchmark calculation in a system which suffers from a strong sign problem, so that our results can be used to test Monte Carlo methods developed to tackle such problems. We analyze here this model by means of analytical techniques, computing exactly the first eight cumulants of the expansion of the effective Hamiltonian in powers of the inverse temperature, and calculating physical observables for a large number of degrees of freedom with the help of standard multi-precision algorithms. We report accurate results for the free energy density, internal energy, standard and staggered magnetization, and the position and nature of the critical line, which confirm the mean-field qualitative picture, and which should be quantitatively reliable, at least in the high-temperature regime, including the entire critical line.

hep-lat↗

arXiv2013

Elucidating the Vacuum Structure of the Aoki Phase

In this paper, we discuss the vacuum structure of QCD with two flavors of Wilson fermions, inside the Aoki phase. We provide numerical evidence, coming from HMC simulations in $4^4$, $6^4$ and $8^4$ lattices, supporting a vacuum structure for this model at strong coupling more complex than the one assumed in the standard wisdom, with new vacua where the expectation value of $i\barψγ_5ψ$ can take non-zero values, and which can not be connected with the Aoki vacua by parity-flavour symmetry transformations.

hep-lat↗

arXiv2012

Resource management on a VM based computer cluster for scientific computing

In the last ten years host virtualization has brought a revolution in the way almost every activity related to information technology is thought of and performed. The use of virtualization for HPC and HTC computing, while eagerly desired, has probably been one of the last steps of this revolution, the performance loss due to the hardware abstraction layer being the cause that slowed down a process that has been much faster in other fields. Nowadays the widespread diffusion of virtualization and of new virtualization techniques seem to have helped breaking this last barrier and virtual host computing infrastructures for HPC and HTC are found in many data centers. In this document the approach adopted at the INFN "Laboratori Nazionali del Gran Sasso" for providing computational resources via a virtual host based computing facility is described. Particular evidence is given to the storage layout, to the middleware architecture and to resource allocation strategies, as these are issues for which a personalized solution was adopted. Other aspects may be covered in the future within other documents.

cs.DC↗

arXiv2012

Critical behaviour of the O(3) nonlinear sigma model with topological term at theta=pi from numerical simulations

We investigate the critical behaviour at theta=pi of the two-dimensional O(3) nonlinear sigma model with topological term on the lattice. Our method is based on numerical simulations at imaginary values of theta, and on scaling transformations that allow a controlled analytic continuation to real values of theta. Our results are compatible with a second order phase transition, with the critical exponent of the SU(2)_1 Wess-Zumino-Novikov-Witten model, for sufficiently small values of the coupling.

hep-lat↗

arXiv2009

Geometric Algorithm for Abelian-Gauge Models

Motivated by the sign problem in several systems, we have developed a geometric simulation algorithm based on the strong coupling expansion which can be applied to abelian pure gauge models. We have studied the algorithm in the U(1) model in 3 and 4 dimensions, and seen that it is practical and is similarly efficient to the standard heat-bath algorithm, but without the ergodicity problems which comes from the presence of vortices. We have also applied the algorithm to the Ising gauge model at the critical point, and we find hints of a better asymptotic behaviour of the autocorrelation time, which therefore suggests the possibility of a smaller dynamical critical exponent with respect to the standard heat-bath algorithm.

hep-lat↗

arXiv2005

Phase diagram of QCD with four quark flavors at finite temperature and baryon density

We analyze the phase diagram of QCD with four staggered flavors in the (mu, T) plane using a method recently proposed by us. We explore the region T > 0.7 Tc and mu <1.4 Tc, where Tc is the transition temperature at zero baryon density, and find a first order transition line. Our results are quantitatively compatible with those obtained with the imaginary chemical potential approach and the double reweighting method, in the region where these approaches are reliable, T > 0.9 Tc and mu < Tc. But, in addition, our method allows us to extend the transition line to lower temperatures and higher chemical potentials.

hep-lat↗

arXiv2005

Phase structure of four flavor QCD in the T μplane from a new method for simulations of lattice gauge theories at non zero baryon density

We review a method for numerical simulations of lattice gauge theories at non-zero baryonic chemical potential we recently proposed. We first report on a test of the method using a solvable model and then present results for the phase structure of four flavour QCD. For the first time the region of chemical potential up to 1.4 T_C is explored, finding a first order transition line.

hep-lat↗

arXiv2005

Finite Density QCD: a New Approach

We introduce a new approach to analyze the phase diagram of QCD at finite chemical potential and temperature, test it in the Gross-Neveu model at finite baryon density, and apply it to the study of the chemical potential-temperature phase diagram of QCD with four degenerate flavors of Kogut-Susskind type.

hep-lat↗

arXiv2004

Strong coupling analysis of diquark condensation

The phenomenon of diquark condensation at non-zero baryon density and zero temperature is analyzed in the strong coupling limit of lattice QCD. The results indicate that there is attraction in the quark-quark channel also at strong coupling, and that the attraction is more effective at high baryon density, but for infinite coupling it is not enough to produce diquark condensation. It is argued that the absence of diquark condensation is not a peculiarity of the strong coupling limit, but persists at sufficiently large finite couplings.

hep-lat↗