The FRB-searching pipeline of the Tianlai Cylinder Pathfinder Array

International audienceThis paper presents the design, calibration, and survey strategy of the Fast Radio Burst (FRB) digital backend and its real-time data processing pipeline employed in the Tianlai Cylinder Pathfinder array. The array, consisting of three parallel cylindrical reflectors and equipped with 96 dual-polarization feeds, is a radio interferometer array designed for conducting drift scans of the northern celestial semi-sphere. The FRB digital backend enables the formation of 96 digital beams, effectively covering an area of approximately 40 square degrees with 3 dB beam. Our pipeline demonstrates the capability to make automatic search of FRBs, detecting at quasi-real-time and classify FRB candidates automatically. The current FRB searching pipeline has an overall recall rate of 88%. During the commissioning phase, we successfully detected signals emitted by four well-known pulsars: PSR B0329+54, B2021+51, B0823+26, and B2020+28. We report the first discovery of an FRB by our array, designated as FRB 20220414A. We also investigate the optimal arrangement for the digitally formed beams to achieve maximum detection rate by numerical simulation

Search for fractionally charged particles with CUORE

International audienceThe Cryogenic Underground Observatory for Rare Events (CUORE) is a detector array comprised by 988 5$\;$cm$\times$5$\;$cm$\times$5$\;$cm TeO$_2$ crystals held below 20 mK, primarily searching for neutrinoless double-beta decay in $^{130}$Te. Unprecedented in size amongst cryogenic calorimetric experiments, CUORE provides a promising setting for the study of exotic through-going particles. Using the first tonne-year of CUORE's exposure, we perform a search for hypothesized fractionally charged particles (FCPs), which are well-motivated by various Standard Model extensions and would have suppressed interactions with matter. No excess of FCP candidate tracks is observed over background, setting leading limits on the underground FCP flux with charges between $e/24-e/5$ at 90% confidence level. Using the low background environment and segmented geometry of CUORE, we establish the sensitivity of tonne-scale sub-Kelvin detectors to diverse signatures of new physics

Énergie et climat : éléments de cours et travaux dirigés

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Accurate measurement of telescope filter bandpasses with a Collimated Beam Projector and impact on cosmological parameters

International audienceThe measurement of magnitudes with different filters in photometric surveys gives access to cosmological distances and parameters. However, for current and future large surveys like the ZTF, DES, HSC or LSST, the photometric calibration uncertainties are almost comparable to statistical uncertainties in the error budget of type Ia cosmology analysis, which limits our ability to use type Ia supernovae for precision cosmology. The knowledge of the bandpasses of the survey filters at the per-mill level can help reach the sub-percent precision for magnitudes. We show how a misknowledge of the bandpasses central wavelengths or of the presence of out-of-band leakages leads to biased cosmological measurements. Then, we present how to measure the filter throughputs at the required precision with a Collimated Beam Projector

Odd-even mass differences of well and rigidly deformed nuclei in the rare earth region: A test of a newly proposed fit of pairing matrix elements

International audienceWe discuss a test of a recently proposed approach to determine average pairing matrix elements within a given interval of single-particle states (sp) around the Fermi level $\lambda$ as obtained in the so-called uniform gap method (UGM). It takes stock of the crucial role played by the averaged sp level density $\tilde{\rho}(e)$. These matrix elements are deduced within the UGM approach, from microscopically calculated $\tilde{\rho}(e)$ and gaps obtained from analytical formulae of a semi-classical nature. Two effects generally ignored in similar fits have been taken care of. They are: (a) the correction for a systematic bias in choosing to fit pairing gaps corresponding to equilibrium deformation solutions as discussed by Möller and Nix [Nucl. Phys. A 476, 1 (1992)] and (b) the correction for a systematic spurious enhancement of $\tilde{\rho}(e)$ for protons in the vicinity of $\lambda$, because of the local Slater approximation used for the treatment of the Coulomb exchange terms in most calculations (see e.g. [Phys. Rev C 84, 014310 (2011)]). This approach has been deemed to be very efficient upon performing Hartree-Fock + BCS (with seniority force and self-consistent blocking when dealing with odd nuclei) calculations of a large sample of well and rigidly deformed even-even rare-earth nuclei. The reproduction of their experimental moments of inertia has been found to be at least of the same quality as what has been obtained in a direct fit of these data [Phys. Rev C 99, 064306 (2019)]. We extend here the test of our approach to the reproduction, in the same region, of three-point odd-even mass differences centered on odd-$N$ or odd-$Z$ nuclei. The agreement with the data is again roughly of the same quality as what has been obtained in a direct fit, as performed in [Phys. Rev C 99, 064306 (2019)]

The coherent magnetic halo of Milky Way

International audienceRecent catalog of Faraday rotation measures (RM) of extragalactic sources together with the synchrotron polarization data from WMAP and Planck provide us with the wealth of information on magnetic fields of the Galaxy. However, the integral character of these observables together with our position inside the Galaxy makes the inference of the coherent Galactic magnetic field (GMF) complicated and ambiguous. We combine several phenomenological components of the GMF -- the spiral arms, the toroidal halo, the X-shaped field and the field of the Local Bubble -- to construct a new model of the regular GMF outside of the thin disk. To have control over the relative contributions of the RM and polarization data to the fit we pay special attention to the estimation of errors in data bins. To this end we develop a systematic method which is uniformly applicable to different data sets. This method takes into account individual measurement errors, the variance in the bin as well as fluctuations in the data at angular scales larger than the bin size. This leads to decrease of the errors and, as a result, to better sensitivity of the data to the model content. We cross checked the stability of our method with the new LOFAR data. We found that the four components listed above are sufficient to fit both the RM and polarization data over the whole sky with only a small fraction masked out. Moreover, we have achieved several important improvements compared to previous approaches. Due to account of our location inside of the Local Bubble our model does not require introduction of striated fields. For the first time we showed that the Fan Region can be modeled as a Galactic-scale feature. The pitch angle of the magnetic field in our fit converged to the value around 20 degrees. Interestingly, with value is very close to the direction of arms inferred recently from Gaia data on upper main sequence stars

Numerical computation of quasinormal modes in the first-order approach to black hole perturbations in modified gravity

International audienceWe present a novel approach to the numerical computation of quasi-normal modes, based on the first-order (in radial derivative) formulation of the equations of motion and using a matrix version of the continued fraction method. This numerical method is particularly suited to the study of static black holes in modified gravity, where the traditional second-order, Schrödinger-like, form of the equations of motion is not always available. Our approach relies on the knowledge of the asymptotic behaviours of the perturbations near the black hole horizon and at spatial infinity, which can be obtained via the systematic algorithm that we have proposed recently. In this work, we first present our method for the perturbations of a Schwarzschild black hole and show that we recover the well-know frequencies of the QNMs to a very high precision. We then apply our method to the axial perturbations of an exact black hole solution in a particular scalar-tensor theory of gravity. We also cross-check the obtained QNM frequencies with other numerical methods

Matter-antimatter (a)symmetry and cosmological constant

We investigate the matter-antimatter asymmetry within the framework of quantum field theory in de Sitter spacetime. While conventional perspectives often attribute this asymmetry to dynamical mechanisms such as CP violation in the early Universe, our analysis proposes a novel kinematical origin. Our findings suggest that this asymmetry may be an observational anomaly, observable only by local observers with causal access to a specific segment of the Universe. This unconventional insight, while grounded in de Sitter cosmology (an idealized scenario for real-world cosmology), has the potential to challenge established perspectives and drive a paradigm shift in our understanding of the observed asymmetry in the distribution of matter and antimatter throughout the Universe

Intertwined quantum phase transitions in the zirconium and niobium isotopes

International audienceNuclei in the $A\approx100$ region exhibit intricate shape-evolution and configuration crossing signatures. Exploring both even-even and their adjacent odd-mass nuclei gives further insight on the emergence of deformation and shape-phase transitions. We employ the algebraic frameworks of the interacting boson model with configuration mixing and the new interacting boson-fermion model with configuration mixing in order to investigate the even-even zirconium with neutron number 52-70 ($^{40}$Zr) and odd-mass niobium ($_{41}$Nb) isotopes with 52-62. We compare between the evolution in energy levels, configuration and symmetry content of the wave functions, two neutron separation energies and $E2$ transition rates. The comparisons between the two chains of isotopes denote the occurrence of intertwined quantum phase transitions (IQPTs) in both chains. Such a situation occurs when two configurations, normal and intruder, cross through the critical point of a Type II quantum phase transition (QPT), and the intruder configuration undergoes on its own a Type I shape-evolution QPT from a spherical shape (weak coupling scenario) to axially deformed rotor (strong coupling scenario) in the Zr (Nb) isotopes

From Nuclear Waste to Hydrogen Production: From Past Consequences to Future Prospect

International audienceNuclear wastes may not be considered as unusable materials in the sense that they deliver a free source of energyunder the form of ionizing radiations that can be used to produce hydrogen (H2) through water radiolysis. Thecurrent paradigm that define these nuclear wastes as troublesome by-products which no one uses nowadays mustbe shifted into a new opportunity for pure H2 production with no CO2 emission. Here, we propose a low-techmethod to boost H2 production by water radiolysis thanks to the catalytic effect of a suspension of TiO2 nano-particles. We also demonstrate the relevance of this concept by scaling up our laboratory results. From ourcalculations, this radiocatalytic process can supply until 60% of the actual global demand in hydrogen (42.9MtH2.y-1) and open the door, together with the green and white hydrogen productions, to the “Hydrogencentury