seminari 2023

1 Jan 2023, 15:00 → 31 Dec 2023, 17:00 Europe/Rome

412C (Room)

Stefania Vecchi (Istituto Nazionale di Fisica Nucleare)

Seminari di Fisica del Dipartimento e della sezione INFN

Tuesday 24 January

16:30 → 17:30 Mineral Detection of Neutrinos and Dark Matter

Abstract: Minerals are solid state nuclear track detectors - nuclear recoils in a mineral leave latent damage to the crystal structure. Depending on the mineral and its temperature, the damage features are retained in the material from minutes to timescales much larger than the age of the Solar System. The damage features from the fission fragments left by spontaneous fission of heavy unstable isotopes have long been used for fission track dating of geological samples. Laboratory studies have demonstrated the readout of defects caused by nuclear recoils with energies as small as ~1 keV. Using natural minerals, one could use the damage features accumulated over geological timescales to measure astrophysical neutrino fluxes (from the Sun, supernovae, or cosmic rays interacting with the atmosphere) as well as search for Dark Matter. Research groups in Europe, Asia, and America have started developing microscopy techniques to read out the nanoscale damage features in crystals left by keV nuclear recoils. The research program towards the realization of such mineral detectors is highly interdisciplinary, combining geoscience, material science, applied and fundamental physics with techniques from quantum information and Artificial Intelligence. In this talk, I will highlight the scientific potential for mineral detectors and briefly describe status and plans of the MDvDM community.

Room: C412
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Speaker: Patrick Stengel (Ferrara University)

Tuesday 31 January

14:30 → 15:30 Probing Cosmic Inflation and Quantum Gravity with the LiteBIRD CMB Polarization Surve

LiteBIRD is a space mission for primordial cosmology and fundamental physics. The Japan Aerospace Exploration Agency (JAXA) selected LiteBIRD as a strategic large-class (L-class) mission, with an expected launch in the late 2020s using JAXA's H3 rocket. LiteBIRD is planned to orbit the Sun-Earth Lagrangian point L2, where it will map the cosmic microwave background (CMB) polarization over the entire sky for three years. The primary scientific objective of LiteBIRD is to search for the signal from cosmic inflation, either
making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. The LiteBIRD collaboration is international with a lot of members from Europe.
In this talk, I provide an overview of the LiteBIRD project.

Room: C412

Speaker: Masashi Hazumi (KEK & ISAS/JAXA)

Monday 6 February

14:30 → 15:30 The interplay of primordial black holes and particle dark matter

The nature of dark matter remains a mystery to date. In this talk, I will present some novel mechanisms to probe the properties of two dark matter candidates, the weakly interacting massive particle and the axion, using black hole physics. I will also discuss how to assess the abundance of black holes in galaxies in these theories.

Speaker: Luca Visinelli (Tsung-Dao Lee Institute (TDLI))

Thursday 16 February

14:00 → 15:00 What is flat ΛCDM, and may we choose it?

The Universe is neither homogeneous nor isotropic, but it is close enough that we can reasonably approximate it as such on suitably large scales. The inflationary-ΛCDM concordance cosmology builds on these assumptions to describe the origin and evolution of fluctuations. With standard assumptions about stress-energy sources, this system is specified by just seven phenomenological parameters, whose precise relations to underlying fundamental theories are complicated and may depend on details of those fields. Nevertheless, it is common practice to set the parameter that characterizes the spatial curvature Omega_k, exactly to zero and call this, "flat ΛCDM'' as though it were a separate model, placing the onus on proponents of "curved ΛCDM'' to present sufficient evidence that Omega_k is not zero. I will explain why Omega_k must not be set to zero, and that ΛCDM remains a phenomenological model with at least 7 parameters.

---- Stanza C400 ------

Speaker: Prof. Glenn Starkman (Case Western Reserve University, Cleveland (USA).)

Thursday 23 February

17:00 → 18:00 Fast radio bursts

Fast radio bursts are a relatively new phenomenon discovered just 15 years ago. They are bright extragalactic radio bursts with typical durations from a fraction of a millisecond up to a few tens of millisecond.
Discovery of similar events simultaneously with high energy bursts from one of the Galactic magnetar confirms the hypothesis that powerful episodes of magnetic energy release in neutron stars can be accompanied by radio flares. Still, there are many unsolved problems related to FRBs.
In the talk I describe general properties of FRBs, discuss two important topics of research -- origin of magnetars producing FRBs and mechanism of radio emission, -- and finally, present how FRB observations are used in fundamental physics to put constraints on some basic parameters and constants.

--- Stanza 300 Blocco C ----

Speaker: Sergei Popov (ICTP - Trieste)

Thursday 2 March

10:00 → 11:00 Multimessenger study of the dark matter interpretation of the Fermi-LAT Galactic center excess

Compelling gravitational evidence has been observed for the existence of dark matter which is five tines more abundant than the baryonic one. However, the exact particle nature of dark matter remains still a mystery. | will focus the seminar on the indirect detection technique which seeks to detect the rarest cosmic rays and radiation (e.g. gamma rays) generated from dark matter annihilation or decay in space.
An excess of gamma rays in the data measured by the Fermi Large Area Telescope from the Galactic center region is one of the most intriguing mysteries in Astroparticle Physics that could be associated to a dark matter signal. The Galactic center excess (GCE), has been measured with respect to different interstellar emission models, source catalogs, data selections and techniques. Although several proposed interpretations have appeared in the literature, there are no firm conclusions as to its origin.
In this presentation | will show the results obtained for the GCE by using 11 years of Fermi-LAT data, state of the art interstellar emission models, and the newest 4FGL source catalog to provide precise measurements of the energy spectrum, spatial morphology, position, and sphericity of the GCE. | will also present constraints for the interpretation as dark matter particle
interactions using the GCE, a gamma-ray analysis of dwarf spheroidal galaxies with LAT data and AMS-02 cosmic-ray antiprotons and positrons flux data.
Finally, I will discuss the dark matter interpretation of the GCE in the context of the simplest model beyond the Standard Model with a dark matter candidate. I will show how much we can learn by combining the results found with cosmic particle fluxes and the precise measurements from cosmology with the constraints coming from direct detection and collider experiments.

Speaker: Mattia Di Mauro (Istituto Nazionale di Fisica Nucleare - Sezione di Torino)

Friday 10 March

14:30 → 15:30 Can we use Baryon Acoustic Oscillations distances?

Baryon Acoustic Oscillations are considered one of the most powerful cosmological probes. They are assumed to provide distance measures independent of a specific cosmological model. At the same time the obtained distances are considered agnostic with respect to other cosmological observations. However, in current measurements, the inference is done assuming parameter values of a fiducial LCDM model and employing prescriptions tested to be unbiased only within some LCDM fiducial cosmologies. Moreover the procedure is plagued by the ambiguity of choosing a specific correlation function model-template to measure cosmological distances.
Does this comply with the requirement of model and parameter independent distances useful, for instance, to characterize cosmological tensions?
In this talk I will review the subject, answer compelling questions and explore new promising research directions.

Speaker: Stefano Anselmi (Istituto Nazionale di Fisica Nucleare)

Thursday 16 March

15:30 → 16:30 Hadron spectroscopy: recent results from BESIII

The theory of the strong interaction, Quantum Chromodynamics, has been probed very successfully up to very high energies, for example using hadron production in electron-positron collisions. At low energy scales, the QCD potential is non-perturbative and still not fully understood.

A `second charm revolution' was sparked with the discovery of new 'XYZ' states, such as the X(3872) or the Y(4260) by the B factories Belle and BABAR, which do not fit into the conventional picture of quark-antiquark bound systems. Recently, a number of further, non-conventional bound states have been seen. In this talk, I will concentrate on some of the more exotic bound states recently discovered at BESIII, and show some of the connections between them being made, both in the charmonium and the light quark sector.

Speaker: Prof. Wolfgang Gradl (Institut für Kernphysik, Johannes Gutenberg-Universität Mainz)

Tuesday 9 May

14:30 → 15:30 Testing the assumptions of ΛCDM

The standard cosmological model (ΛCDM) has shown a great ability to explain cosmological observations throughout the past 3 decades. Despite this, several of its components are still a mystery from the theoretical point of view; together with the observational tensions recently found between different measurements of its parameters, this motivates the search for alternative models or, at least, a thorough testing of ΛCDM. In this talk, I will focus mostly on tests of one of the crucial assumptions done in cosmology, i.e. that General Relativity is a good description of gravity at cosmological scale, showing recent constraints and how upcoming surveys might improve our knowledge. In addition to this I will also show results on other more fundamental assumptions, namely the validity of the Distance Duality Relation and on the possible variation of the fine-structure constant. Finally, I will also briefly summarize how new cosmological observables might shed new light on the dark component of the standard cosmological model.

Speaker: Matteo Martinelli (Osservatorio Astronomico di Roma-INAF)

16:00 → 17:00 Quantum firmware: optimal control for quantum simulators

Quantum optimal control has been shown to improve the performance of quantum technology devices up to their limits in terms e.g. of system size and speed of operation. This talk will review our recent results with a variety of quantum technology platforms, focusing in particular on ultracold atoms, and introduce our newly developed software for automatic calibration of quantum operations - the fundamental building block of
next-generation quantum firmware.

Speaker: Prof. Tommaso Calarco (Forschungszentrum Jülich)

zoom link

Tuesday 16 May

14:00 → 15:00 Machine learning-infused cosmology: overview and examples

In recent years, machine learning (ML) has emerged as a powerful tool for cosmological research, facilitating the extraction of information from and the analysis of vast amounts of data, collected by modern astronomical surveys. In this seminar, after giving a brief overview of ML, I will discuss three topics of my own research where I use ML techniques to address key challenges in cosmology: 1) an ML algorithm that detects galaxy clusters in survey images, 2) a Boltzmann code emulator for faster predictions, and 3) a novel ML-based Bayesian inference method to perform flexible and efficient parameter inference in cosmological models. Overall, these machine learning techniques demonstrate the potential for artificial intelligence to accelerate progress in cosmology and other fields of science, enabling researchers to tackle complex problems and extract new insights from large and complex datasets.

Speaker: Stéphane Ilic (IJCLab)

Tuesday 30 May

14:30 → 15:30 Fast Radio Bursts: A new look at the visible Universe

Fast radio bursts (FRBs) are very short and bright transients visible over extragalactic distances. Their origin is still a mystery, but since the radio pulse undergoes dispersion caused by free electrons along the line of sight, FRBs can be used to probe the distribution of baryons on cosmological scales.
In this talk we will give a brief overview of this rapidly evolving field. Recently, we used the small sample of currently known events to measure the Hubble constant, and constraints are expected to improve considerably in the near future as more and more data from the ongoing search programs becomes available. Future large FRB samples provide exciting opportunities not only to understand the physical mechanism, but also to use their dispersion to measure the cosmic electrons on largest scales and to look for new physics such as primordial non-Gaussianity or deviations from the equivalence principle. The unique perspective FRBs offer on the baryon distribution allows to study feedback processes on cosmological scales and promises great complementarity with upcoming large-scale structure surveys.

Speaker: Robert Reischke and & Steffen Hagstotz

Tuesday 13 June

11:00 → 12:00 Beam Delivery for the Mu2e Experiment and the use of crystal channeling at Fermilab

The Mu2e experiment is at the stage of assembly and preparations for the commissioning and taking data at Fermilab. In this presentation we will focus on the beam delivery for the Mu2e proton target. One of the main challenges of the beam delivery is the beam losses and radiation levels in the public areas. We will discuss the effort to mitigate the beam losses with the use of crystal collimation (shadowing) and a preliminary analysis of its effectiveness.

Speaker: Vladimir Nagaslaev (FNAL - Mu2e collaboration)

Wednesday 14 June

17:00 → 18:00 Quark Stars: Formation, Existence, and Identification

The existence of quark stars is an open problem in astrophysics, and the quest to find such stars has attained a lot of focus in recent years. According to a conjecture of QCD, at extreme densities found in neutron star interior, the normal nuclear matter is no longer the stable ground state, and it is prone to convert to 3-flavor quark matter (u, d, s quark matter), which is the ground state at such densities. We addressed the shock-induced phase transition scenario by performing simulations in general relativistic hydrodynamics code (GR1D). The simulation reveals the conversion time to be 30-50 microseconds, which indicates a rapid process. This time scale differs from previous studiesinvolving simple analytical estimates. The obtained gravitational wave signal is short-lived (burst-type) with a frequency of about 100 kilohertz and may be observed in future high-frequency GW detectors. The aftermath of deconfinement is 2-flavor quark matter (u,d) to 3-flavor quark matter (u,d,s) conversion and distinct emissions can originate from it. The time scale and energy budget available indicate that short gamma-ray bursts and fast radio bursts could arise in phase transition events. Further, we have addressed the spin-down driven phase transition scenario, wherein magnetic braking drives neutron stars from their birth (Keplerian rotation) to later stages of life (slow spin). The density rise during spin-down can lead to the formation of a quark core or the growth of an existing quark core (from birth). Such progressive phase transitions differ from catastrophic ones and can produce persistent or multiple transient signals (braking index changes, GWs from excited oscillation modes, neutrino bursts). Detecting these multi-messenger signals and their sky localization may help find the quark/hybrid stars formed via phase transition.

Speaker: Prasad Ravichandran (International Centre for Theoretical Sciences (ICTS-TIFR), Bengaluru, India)

Thursday 15 June

15:00 → 16:00 The Hunt for Dark Matter - First Search Results from the LZ experiment

The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility in Lead, South Dakota, USA. I will discuss the results from LZ’s first search for Weakly Interacting Massive Particles (WIMPs) with an exposure of 60 live days using a fiducial mass of 5.5 tonnes were recently published. A profile-likelihood analysis shows the data to be consistent with a background-only hypothesis, setting new limits on spin-independent WIMP-nucleon cross-sections for WIMP masses above 9 GeV/c2 . The most stringent limit is set at 30 GeV/c2 , excluding cross sections above 5.9 × 10-48 cm2 at the 90% confidence level.

I will also discuss the dark matter and neutrino science program that is now accessible with the LZ experiment, and also review the status of other direct dark matter search programs.

Speaker: Richard Gaitskell (Brown University)

Monday 26 June

14:30 → 15:30 Slowing down light in vacuum with intense laser pulses: the DeLLight experiment

Quantum electrodynamics (QED) predicts that the vacuum must be a non-linear optical medium: the speed of light in the vacuum should decrease when the vacuum is subjected to intense electromagnetic fields. This amazing property of vacuum has never been observed before. The DeLLight (Deflection of Light by Light) experiment seeks to measure this effect using ultra-intense femtosecond laser pulses produced by the LASERIX platform (E =2.5J, 30fs, 10Hz) at the IJCLab (Université Paris-Saclay). The innovative method of DeLLIght is to measure by interferometry the refraction of a laser pulse (probe) of low energy, induced by the vacuum index gradient produced by an external pulse (pump) of high intensity. The refraction of the probe pulse is detected using a Sagnac interferometer.
In this colloquium, I will start by explaining briefly the scientific motivations of the study of the optical vacuum index. I will then describe the experimental method and the technical challenges of the DeLLight project. Finally I will present the recent results obtained with the DeLLight pilot experiment, with low energy pump laser pulses in air, validating the experimental method.

Speaker: Adrien Kraych (Laboratoire Irène Joliot Curie Physique des 2 Infinis, Université Paris-Saclay, CNRS)

Tuesday 4 July

11:00 → 12:00 Modeling short GRB jet propagation in realistic post-merger scenarios

The multimessenger event of August 17, 2017, demonstrated that binary neutron star (BNS) systems can merge and power collimated relativistic outflows (jets) that are compatible with the prompt and afterglow emission of short gamma-ray bursts (GRBs). However, many open questions remain about the physical mechanisms behind this connection, calling for advanced numerical modeling of the merger and jet propagation stages up to the formation of electromagnetic signals. In this talk, I will present results of three-dimensional relativistic (magneto)hydrodynamic short GRB jet simulations that we carried out by employing, for the first time, self-consistent initial conditions for the jet propagation environment directly imported from the outcome of general-relativistic BNS merger simulations, also carried out by our group. The results presented will soon allow us to make direct and more solid comparisons with the afterglow data of 170817, establishing a powerful new approach for the interpretation of similar events in the future.

Speaker: Andrea Pavan (Universita di Padova)

Thursday 6 July

14:30 → 15:30 AlphaZero and the new style of chess playing by machines

I will discuss the algorithms at the base of AlphaZero, the computer
program which, by using a variety of techniques of Artificial
Intelligence, learnt by itself how to play Chess, Go and Shogi. I will
compare the structure of such a code with that of more traditional
programs and I will also discuss how the new structure is able to select
moves which are, to a certain extent, more “human” than those generated by
traditional programs.

The first part of the talk will be more technical, and I will discuss the
mechanisms which allow AlphaZero to select a move, the second part will be
of interest mostly for people who know how to play chess, since I will
discuss in detail a few games played by AlphaZero.

Silver et al., Science 362, 1140–1144 (2018)
“Game changer”, by Matthew Sadler and Natasha Rega. New in Chess 2019.

Speaker: Alessandro Drago (Istituto Nazionale di Fisica Nucleare)

Monday 10 July

15:00 → 16:00 X-ray spectral micro-CT imaging: principles, implementations, and biomedical applications

X-ray Micro-computed tomography (CT) is the gold standard for assessing the 3D nature of details down to a few microns within samples in the centimeter length scale. Micro-CT spans a wide range of applications, from industrial inspection to biomedical imaging. When dealing with biological samples, the main limitation of X-ray CT is the poor attenuation contrast among different soft tissues. To overcome this limitation, radio-opaque contrast agents selectively accumulating in, or binding to, tissues of interest are used in the so-called contrast-enhanced CT. Despite mitigating the limited visibility issue, contrast-enhanced CT does not provide material-specific quantitative information (e.g. mass density) and does not allow to distinguish between co-localized radio-opaque objects (e.g. bone and iodine).
The advent of spectral imaging techniques solves this ambiguity by resolving the energy-attenuation dependence of different chemical elements. This results in quantitative and independent maps of two or more materials/compounds.
In this seminar, the principles underlying spectral imaging CT will be outlined as well as state-of-the-art implementations both at synchrotrons and with compact laboratory microfocal sources. A focus will be dedicated to the novel compact multi-modal imaging setup – PEPI Lab – developed at INFN Trieste. Various applications, including osteoarticular, cardiovascular, and multi-material imaging will be presented as well as a direct comparison between conventional and spectral micro-CT.

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Speaker: Luca Brombal (Universita' degli studi di Trieste)

Thursday 20 July

15:30 → 16:30 Constraining dark matter with strong lensing and hydro simulations

It has been demonstrated that strong gravitational lensing is one of the most promising methods to distinguish between cold and alternative dark matter models. Warm dark matter can be constrained through the detection of low-mass dark haloes and subhaloes, while self-interacting dark matter influences the halo density profiles and thus (for example) the number and size of lensed images. New simulations that correctly model both dark matter and baryon physics are necessary to provide a realistic picture of structure formation in all scenarios.
I will discuss what is the status of the field and the current dark matter constraints in general, and in particular, present the latest results from my work and that of my collaborators, focusing on the properties of galaxies in different scenarios and the near-future prospects of more precise dark matter constraints thanks to upcoming observations.
Using real and mock observations, we quantify the data sensitivity in detail and calculate forecasts for HST, Keck, Euclid and ALMA observations. At the same time, we use hydrodynamical simulations to predict observed properties of galaxies and gravitational lenses in different dark matter scenarios and compare them with observations.

Speaker: Giulia Despali (UniBo)

Monday 11 September

15:00 → 16:00 A new channel for supermassive black hole formation

Observations support the idea that supermassive black holes (SMBHs) power the emission at the center of active galaxies. However, contrary to stellar-mass BHs, there is a poor understanding of their origin and physical formation channel. In this talk, we propose a new process of SMBH formation in the early Universe that is not associated with baryonic matter (massive stars) or primordial cosmology. In this novel approach, SMBH seeds originate from the gravitational collapse of fermionic dense dark matter (DM) cores that arise at the center of DM halos as they form. We show that such a DM formation channel can occur before star formation, leading to heavier BH seeds than standard baryonic channels. The SMBH seeds subsequently grow by accretion. We compute the evolution of the mass and angular momentum of the BH using a geodesic general relativistic disk accretion model. We show that these SMBH seeds grow to ~ 10^9-10^(10) Msun in the first Gyr of the lifetime of the Universe without invoking unrealistic (or fine-tuned) accretion rates. Based on doi: 10.1093/mnras/stad1380

Speaker: Carlos Arguelles (Universidad de La Plata (Argentina))

Thursday 21 September

16:45 → 17:45 Operando DRIFTS inputs on sensing with SMOX -based device

The characteristic features especially the high sensitivity, stability, and potential for miniaturization of s emiconducting metal oxide based gas sensors is making them suitable candidates for many relevant applications . Most of their development was done based on a try and see approach, which resulted in an initial rapid improvement of the sensor performance. However, further improvements are limited by the lack of full understanding of sensing as it takes place in applic ation conditions. A very successful approach is represented by the Diffuse Reflectance Infrared Fourier Transformed Spectroscopy applied in operation conditions, id est. on heated sensors in air and in the presence of humidity and target gases.
The lecture will describe the investigation approach and provide examples such as: the impact of ambient humidity on the detection of CO with SnO 2 and WO 3 based gas sensors; the effect of surface loading on the detection of various reducing gases with SMOX based materials; the surface chemistry of hydrocarbons detection with WO 3 based gas sensors.

Speaker: Nicolae Barsan (Institute of Physical and Theoretical Chemistry and Center for Light-Matter Interaction, Sensors & Analytics (LISA+), University of Tübingen, 72076 Tübingen, Germany)

Tuesday 10 October

14:30 → 15:30 Early galaxy formation observed by orbital Hubble and James Webb telescopes with possible implications for generation of cosmological lepton asymmetry with heavy neutrino capture the primordial black holes

Speaker: Alexander Dolgov

15:30 → 16:30 Gravitational baryogenesis and the role of neutrinos in generation of ultra high energy cosmic rays

Speaker: E. Arbuzova

Friday 27 October

11:00 → 12:00 Synergies across the spectrum for cosmology and astroparticle physics

I shall review novel approaches that I have explored over the years to extract information optimally from varied observations across the electromagnetic spectrum. The aims are varied as well, and in particular I shall discuss: optimising parameter constraints for the concordance cosmological model; testing the inflationary principle through measuring its non-Gaussian imprint on the cosmic large-scale structure; confirming the validity of general relativity on the largest cosmic scales; probing the particle nature of dark matter; and learning about the origin and composition of ultra-high energy cosmic rays.

Speaker: Prof. Stefano Camera (Università degli Studi di Torino & INFN Torino)

Wednesday 8 November

15:00 → 16:00 Searching for dark energy off the beaten track

Most of our attempts towards understanding dark energy (DE) have focused on using standard cosmological observations to probe its gravitational signatures, and in particular its equation of state. However, there is potentially a lot to be learned about DE by getting off the beaten track. This talk will discuss recent results of my work in this direction, which include developing new terrestrial searches for non-gravitational signatures of DE and new ultra-light particles, as well as cosmological and astrophysical tests of DE based on new non-standard probes.

Speaker: Sunny Vagnozzi (Universita di Trento (Italy))

Thursday 9 November

14:00 → 15:00 Discovering multi-messenger counterparts with wide-field optical telescopes

We live in a golden era for optical time-domain astronomy. The fourth observing run of the LIGO-Virgo-KAGRA gravitational wave detectors is in full swing: observatories around the world follow up compact binary mergers that are more likely to have luminous electromagnetic counterparts. I will present preliminary results from the follow-up observations of gravitational wave sources with the Zwicky Transient Facility (ZTF) and the Dark Energy Camera, a sensitive instrument located in Chile. ZTF images most of the observable sky every night, opening a discovery space historically difficult to explore in the optical and gifting us with occasional “gems”, including the first optically-identified relativistic tidal disruption event, named AT2022cmc. Finally, I will present prospects for kilonova and fast transient discovery with two upcoming facilities: the Vera C. Rubin Observatory (LSST) and the Nancy Grace Roman Space Telescope.

Speaker: Igor Andreoni (Joint Space-Science Institute (University of Maryland & NASA Goddard Space Flight Center))

Monday 13 November

15:00 → 16:00 Introduzione ai diodi laser

I seminari sono rivolti a studenti della laurea in Fisica e a studenti del dottorato di ricerca per illustrare i principi, la tecnologia costruttiva e il funzionamento di diodi ad emissione di luce laser. Verrà illustrata la modalità di fabbricazione epitassiale di giunzioni p-n e l’integrazione della eterostrutture con una cavità di confinamento per l’emissione della luce laser. Nel secondo seminario, verranno trattati i fenomeni di guasto caratteristici dei diodi laser e saranno presentate le metodologie di microscopia elettronica che vengono utilizzate per studiare i fenomeni di degrado.

Speaker: Prof. Massimo Vanzi (Istituto di Microelettronica e Microsistemi del CNR)

Wednesday 15 November

15:00 → 16:00 Analisi di guasto in diodi laser

I seminari sono rivolti a studenti della laurea in Fisica e a studenti del dottorato di ricerca per illustrare i principi, la tecnologia costruttiva e il funzionamento di diodi ad emissione di luce laser. Verrà illustrata la modalità di fabbricazione epitassiale di giunzioni p-n e l’integrazione della eterostrutture con una cavità di confinamento per l’emissione della luce laser. Nel secondo seminario, verranno trattati i fenomeni di guasto caratteristici dei diodi laser e saranno presentate le metodologie di microscopia elettronica che vengono utilizzate per studiare i fenomeni di degrado.

Speaker: Prof. Massimo Vanzi (Istituto di Microelettronica e Microsistemi del CNR,)

Wednesday 22 November

14:00 → 15:00 Simulating Binary Neutron Star Mergers and their Kilonova Light Curves

The various phenomena of binary neutron star mergers allow us to study and explore a plethora of topics in modern physics, covering research areas from cosmic to subatomic scales. In addition to gravitational waves, electromagnetic signals may be generated in the ejected material, such as the kilonova, which is triggered by the radioactive decay of the elements formed in the ejecta. Simulations based on numerical relativity are crucial to understand the nature of these phenomena and to create accurate models against which observational data can be compared.
We can use the ejecta data from these simulations as input to radiative transfer simulations to obtain the kilonova directly related to the binary parameters. However, numerical-relativity simulations are usually very short and cover only a few tens of milliseconds after the merger due to the high computational costs. Typically, radiative transfer codes subsequently assume a homologous expansion of the outflowing material, which is not necessarily valid at this stage. In fact, we found in our simulations that the actual expansion deviates by more than 30 % from a homologous one until about 100ms after the merger. To determine the impact on the kilonova light curves, we used ejecta data extracted at different times, which showed negligible deviations only for extraction times later than ~ 80ms after the merger. These results highlight the need for a more careful approach in linking numerical-relativity simulations with radiative transfer calculations and motivate ongoing efforts to optimize this process for accurate light curve modeling.

Speaker: Anna Neuweiler (University of Potsdam)

Wednesday 6 December

15:15 → 15:30 Christmas Lectures on Medical Physics: Introduction

Speakers: Angelo Taibi (Istituto Nazionale di Fisica Nucleare), Paolo Cardarelli (Istituto Nazionale di Fisica Nucleare)

15:30 → 16:15 Investigations of innovative scanning geometries in cone-beam computed tomography

Can cone-beam computed tomography (CBCT) be used for computation of radiotherapy treatment plans? Can it be used for radiomic feature extractions? And for bone density assessment?
At the state-of-the-art, CBCT high effectiveness/cost ratio, versatility and small dimensions determine its advantages with respect to other technologies and make of it of fundamental in routine medical imaging with its use spanning between dentomaxillofacial radiology, radiotherapy treatments, musculoskeletal system imaging, angiography and interventional radiology and advanced 3D breast imaging techniques. However, CBCT presents two intrinsic limitations which negatively affect image quality: 1) the large amount of the scatter radiation reaching the detector and 2) the cone-shaped x-ray beam rotating in a circular trajectory. The first causes both low-frequency noise and low-frequency artifacts and the second is source of 3D image degradation for portion of the field-of-view far from the plane containing the source trajectory. As main consequence of these images’ shortcoming, the use of CBCT is compromises in all those applications aiming at quantitative analysis in the reconstructed 3D images. Hence, CBCT is a no-standing alone imaging technology in several applications, such as radiotherapy treatment workflow, in the evaluation of the mineral bone density, in breast cancer diagnosis, in the repeatability and reproducibility of radiomic features, in the detection of small skeletal lesions, in pre- and post- surgical implant valuations and in automatic image segmentation.
In this talk I will discuss the Q-CT research project, which proposes to move forward the use of such a technology, opening its use to a wide brand-new applications such as: quantitative imaging or automatic computation in radiotherapy treatment planning, characterization of small skeletal lesions, image guided radiotherapy, improved visibility of microcalcifications in breast CT, low-dose 3D breast and maxillofacial imaging, bone mineral density assessments, intraoperative and postoperative assessments, spectral CBCT, automation of image segmentation and extraction of radiomic features.
This seminar aims at showing criticisms of the actual technology and to present the new proposed solution along with evidence of its potential toward the reduction of limitations of the conventional CBCT scanners.

Speaker: Dr Antonio Sarno (Istituto Nazionale di Fisica Nucleare)

16:15 → 16:30 Coffee - Room 400C

16:30 → 17:15 The Birth, the Growth and the Future of Physics in Medical Imaging

The birth of Medical Physics could be dated to more than 2500 years ago to Hippocrates (460-377 BC), a physician from Kos, better known as the “Father of Medicine”. However, it took until 1778 when in Paris the “Société royale de medicine” introduced the term “Physique Medicale” (Medical Physics) that has been used after since. On November 8, 1895, Wilhelm Rontgen discovered the X-rays, and everything changed: Radiology, Radiotherapy and Radioprotection were born. The discovery of the radioisotopes by Marie and Pierre Curie and Henri Becquerel, the theory of the tracer by the chemist Gyorgy Hevesy and the invention of the cyclotron by Ernst Orlando Lawrence in 1929 for producing gamma-emitter radioisotopes such as 99mTc, and positron emitters such as 11C and 18F paved the way to the new specialty of Nuclear Medicine and to the two novel Medical Imaging techniques, i.e, Single Photon Emission Tomography (SPECT) and Positron Emission Tomography (PET). Then, by the end of the 20th century, the Physics in Medical imaging had completed its roster: the Computed Tomography (CT) was joined by the Optical Imaging techniques (Bioluminescence and Fluorescence), UltraSound, Magnetic Resonance Imaging (MRI), functionalMRI (fMRI), and very recently, Photoacoustic.
In this talk I will shortly illustrate the state of the art of these techniques in the clinics with a special emphasis to PET and to the most recent applications of Hybrid Imaging (PET-MR; PET in Particle Therapy and MR driven Radiotherapy). Finally, I will make some speculations on the future developments of Physics in Medical Imaging with the advent of the personalized medicine.

Speaker: Alberto Del Guerra (Istituto Nazionale di Fisica Nucleare)

Wednesday 13 December

12:00 → 13:00 Gravitational wave search through electromagnetic telescopes

We study the graviton-photon conversion in the magnetic fields of the
Earth, pulsars, our galaxy, and intergalactic regions.
Requiring that the photon flux converted from gravitons does not exceed
the observed photon flux with telescopes, we derive upper limits on the
stochastic gravitational waves in frequency ranges from 10^7Hz to 10^35Hz.
The detection of gravitational waves using telescopes may open up a new
avenue for high frequency gravitational wave observations.

Zoom link: https://infn-it.zoom.us/j/7834744241

Speaker: Asuka Ito (KEK)

Tuesday 19 December

15:30 → 16:30 Overview of CNR-IMM Bologna research activities on chemical sensors and microsystems, with particular highlight on "Novel system-in-package digital MOX sensors with exceptional identification capabilities enabled by impedance readout and machine learning"

The seminar will start with a brief overview of the main CNR-IMM Bologna R&D activities on Chemical and Physical Microsystems. CNR-IMM Bologna is equipped with a 500m2 Clean-Room for Research and Development of Microelectronics, Microsystems and Nanomaterials. In the field of Microsystems, the two Research groups on “Physical MEMS” and “Chemical MEMS” have a long-lasting expertise on high-TRL development of Sensors and Microsystems, including successful technology transfer towards Italian and international SMEs and start-up creation.
Then, the seminar will focus on the recent work on the “Smart Cable Air” (SCA) device, which is a multi-sensor system-in-package (SiP) conceived and designed by Sensichips srl [1] in collaboration with the University of Pisa and CNR-IMM Bologna. SCA is based on the SENSIPLUS microchip, which integrates a fully featured Electrochemical Impedance Spectrometer (EIS) with general purpose re-configurable analog front-ends and uses a multi-drop single wire serial bus interface conceived for distributed sensor arrays for large area monitoring (“Smart Cables”) that can be configured up to 150 meters long. The SENSIPLUS microchip is developed in a 0.18um mixed signal CMOS process and fabricated at the UMC semiconductor foundry in Taiwan. SENSIPLUS is used to drive and acquire SENSIMOX, a MEMS-based Ultra-Low-Power (ULP) Metal Oxide Seminconductor (MOX) sensor array, described previously in [2] and optimized in terms of die size, pad layout and sensing layer composition. A particular characteristic of the optimized SENSIMOX sensors is the nanostructured tin oxide (SnO2) thin-film sensing layer, which is deposited at wafer level by means of the M-RGTO process described in [3]. This allows for the batch fabrication of over 3000 sensor arrays on a single 4” wafer, with high reproducibility at a low cost. The SCA device performs EIS sensing layer readout and fast temperature cycled operation (TCO) of the sensor hotplate for discriminative gas classification.
The combination of SENSIPLUS with SENSIMOX in a miniature SiP, complemented by the proprietary SENSIPLUS Learning Machine (SLM) algorithms, has enabled the team to demonstrate a miniature multisensory gas sensing device (size 5.5 mm, weight 0.37 g and 2.5 mW average power consumption) with unparalleled classification and identification capabilities.

[1] https://sensichips.com/smart-cable-air/

[2] I. Elmi et al., Sensors and Actuators: B. Chemical 135 (2008) 342-351

[3] I. Elmi et al., Sensors and Actuators: B. Chemical 131 (2008) 548-555

Speaker: Stefano Zampolli (CNR-IMM Bologna)

Wednesday 20 December

14:00 → 15:00 Numerical estimation of early-stage kilonovae ejecta opacity reproducible in laboratory plasmas

In the Universe, elements beyond the 56Fe's peak are synthesized by the slow (s-) and rapid (r-) neutron capture nucleosynthesis processes. The former takes place in AGB (Asymptotic Giant Branch) stars, while the astrophysical loci of the latter are still unclear. This has led the scientific community to investigate exotic phenomena such as the coalescence of compact binary objects. In the context of the multi-messenger astronomy, thanks to the observations of the GW170817 event, neutron star mergers have been addressed as one of the most eligible candidate for the r-process. The thermal transients generated after the coalescence are known as Kilonovae (KNe). They are powered by the radioactive decay of neutron-rich isotopes and strongly depend on the opacity. Numerical simulations have been performed in the framework of the PANDORA (Plasma for Astrophysics Nuclear Decay Observation and Radiation for Archaeometry) project that aims at measuring, for the first time, plasma opacities relevant for the the KN ejecta environment. In this context, numerical estimates of plasma opacity for selected light r-process nuclei will be presented. In addition, we will highlight how the inclusion of atomic inputs provided by relativistic codes such as GRASP and DIRECT in dedicated collisional-radiative models for laboratory plasmas could better address the opacity estimation of KNe. These results will be relevant to shed light and bridge the gap between theoretical predictions and observations.

Speaker: Matteo Bezmalinovich (Ph.D. student INAF-OAAb e Università Sapienza Roma)

15:45 → 16:45 FLASH radiotherapy: challenges and novel dosimetric approaches

FLASH radiotherapy (RT) is attracting a significant interest since the first investigations carried out in 2014 [1]. Several preclinical studies worldwide have demonstrated that ultra-high dose rate (UHDR) beams produce an improvement of normal tissue sparing, compared to conventional dose-rate RT, while maintaining same tumor control probability (FLASH effect). However, to fully understand the mechanisms behind the effect and to support the future clinical translation of FLASH radiotherapy, novel beam monitoring and dosimetry technologies must be developed, and new approaches studied. Currently used detectors for conventional radiotherapy reference dosimetry, such as ionization chambers, are affected by large ion recombination effects at these extreme regimes [2]. Therefore, the optimization of already established technologies as well as the investigation of new instrumentation for dosimetry is required. Alternative approaches, such as calorimetry or the use of solid-state detectors are currently being investigated and their usage at UHDRs is under assessment [3]. The challenges characterizing dosimetry for FLASH radiotherapy vary considerably depending on the accelerator type and technique used to produce the relevant UHDR radiation environment. Different beam pulse structures can be used for the acceleration of the radiation beams, depending on the specific accelerator, and the related dose and dose-rate per pulse can affect the detector response. A reliable measurement also of the instantaneous dose rate, beyond an accurate measurement of the dose, is also relevant at these extreme regimes. The main challenges coming from the peculiar beam parameters characterizing UHDR beams for FLASH RT will be reported. A status of the current technologies will be provided, including recent developments for established detectors and novel approaches currently under investigation, such as calorimetry and Silicon Carbide detectors [4]. Future perspectives in terms of dosimetric approaches and on-going initiatives at the national and international level for the clinical translation of FLASH RT will be also discussed.

[1] V. Favaudon et al., Science Translational Medicine, 6(245), 245ra93 (2014).
[2] M. McManus M., SCIENTIFIC REPORTS, vol. 10, ISSN: 2045-2322 (2020).
[3] F. Romano et al., Medical Physics, 49:4912-4932. (2022), doi: https://doi.org/10.1002/mp.15649
[4] F. Romano et al., Appl. Sci. 2023, 13(5), 2986; https://doi.org/10.3390/app13052986

Speaker: Francesco Romano (INFN - Catania Section)