ABSTRACT
Core-collapse Supernovae (SNe) are one of the most energetic events in the Universe, during which almost all the star's binding energy is released in the form of neutrinos. These particles are direct probes of the processes occurring in the stellar core and provide unique insights into the gravitational collapse. RES-NOVA will revolutionize how we detect neutrinos from astrophysical sources, by deploying the first ton-scale array of cryogenic detectors made from archaeological lead. Pb offers the highest neutrino interaction cross-section via coherent elastic neutrino-nucleus scattering (CEνNS). Such process will enable RES-NOVA to be equally sensitive to all neutrino flavours. For the first time, we propose the use archaeological Pb as sensitive target material in order to achieve an ultra-low background level in the region of interest (O(1 keV)). All these features make possible the deployment of the first cm-scale neutrino telescope for the investigation of astrophysical sources. In this contribution, we will characterize the radiopurity level and the performance of a small-scale proof-of-principle detector of RES-NOVA, consisting in a PbWO4 crystal made from archaeological-Pb operated as cryogenic detector.
ABSTRACT
The classical Angström exponent is an operationally robust optical parameter that contains size information on all optically active aerosols in the field of view of a sunphotometer. Assuming that the optical effects of a typical (radius) size distribution can be approximated by separate submicrometer and supermicrometer components, we show that one can exploit the spectral curvature information in the measured optical depth to permit a direct estimation of a fine-mode (submicrometer) Angström exponent (alpha(f)) as well as the optical fraction of fine-mode particles (eta). Simple expressions that enable the estimation of these parameters are presented and tested by use of simulations and measurements.
ABSTRACT
Estimation of particle-size distribution is analyzed for the complicated case of compound aerosols, in which particles are distinguished by sizes and optical constants. This task arises in a number of interesting practical situations when aerosol scatterers cannot be described with a common refractive index. This is an inverse problem with a large number of variables, and questions of formal inversion are of great importance here. They are discussed in detail, and an improved numerical-inversion method is proposed. The method provides a nonnegative and highly stable solution and makes it possible to include varied additional or a priori information. It is shown that the proposed technique is closely related to well-known linear and relaxation methods widely used in atmospheric optics. The algorithm for determination of bicomponent aerosol-size distribution is devised. It uses the intensity of light scattered at different angles and spectral-extinction measurements. In addition, the algorithm can incorporate a priori restrictions of size-spectra smoothness. A set of numerical examples illustrates the algorithm.
