arXiv subjects

E. Mariotti

Publications and source records attributed to E. Mariotti.

9 recordsLinked to original sources

arXiv2025

Monte Carlo simulation of the ISOLPHARM gamma camera for Ag-111 imaging

Targeted Radionuclide Therapy (TRT) is a well-established technique for cancer treatment. In this approach, radionuclides are bound to specific drugs that selectively transport them to the tumor site. Within the ISOLPHARM project, a radiopharmaceutical for TRT based on the innovative radionuclide Ag-111 is currently under development. Ag-111 has a half-life of 7.45 days and decays by emitting both electrons and gamma-rays. The emission of gamma-rays, predominantly at an energy of 342 keV, enables the visualization of Ag-111 using a gamma camera. In this work, we describe a Monte Carlo simulation developed to optimize the design parameters of such an imaging device. The simulation is based on the Geant4 toolkit, which accurately models the interactions between particles and matter. The estimated spatial resolution and sensitivity of the system are approximately 4 mm and 19 cps/MBq, respectively. The simulated device is able to resolve lesions with a lesion-to-background activity ratio of 4:1 under in-vivo-like conditions. These results indicate that the proposed gamma camera can provide cost-effective imaging capabilities for preclinical radiopharmaceutical studies.

physics.med-ph↗

arXiv2022

Polarimetry for measuring the vacuum magnetic birefringence with quasi-static fields: a systematics study for the VMB@CERN experiment

We present an experimental systematics study of the polarimetric method for measuring the vacuum magnetic birefringence based on a pair of rotating half-wave plates. The presence of a systematic effect at the same frequency as the sought for magneto-optical effect inhibits the use of strictly constant magnetic fields. We characterise this systematic, discuss its origin and propose a viable workaround.

physics.optics↗

arXiv2021

IACT event analysis with the MAGIC telescopes using deep convolutional neural networks with CTLearn

The Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescope system consists of two imaging atmospheric Cherenkov telescopes (IACTs) and is located on the Canary island of La Palma. IACTs are excellent tools to inspect the very-high-energy (few tens of GeV and above) gamma-ray sky by capturing images of the air showers, originated by the absorption of gamma rays and cosmic rays by the atmosphere, through the detection of Cherenkov photons emitted in the shower. One of the main factors determining the sensitivity of IACTs to gamma-ray sources, in general, is how well reconstructed the properties (type, energy, and incoming direction) of the primary particle triggering the air shower are. We present how deep convolutional neural networks (CNNs) are being explored as a promising method for IACT full-event reconstruction. The performance of the method is evaluated on observational data using the standard MAGIC Analysis and Reconstruction Software, MARS, and CTLearn, a package for IACT event reconstruction through deep learning.

astro-ph.IM↗

arXiv2014

Giant modification of atomic transitions probabilities induced by magnetic field: forbidden transitions become predominant

Magnetic field-induced giant modification of probabilities for seven components of 6S1/2 (Fg=3) - 6P3/2 (Fe=5) transition of Cs D2 line forbidden by selection rules is observed experimentally for the first time. For the case of excitation with circularly-polarized laser radiation, the probability of Fg=3,mF=-3 - Fe=5,mF=-2 transition becomes the largest among 25 transitions of Fg=3 - Fe=2,3,4,5 group in a wide range of magnetic field 200 - 3200 G. Moreover, the modification is the largest among D2 lines of alkali metals. A half-wave-thick cell (length along the beam propagation axis L=426 nm) filled with Cs has been used in order to achieve sub-Doppler resolution which allows for separating the large number of atomic transitions that appear in the absorption spectrum when an external magnetic field is applied. For B > 3 kG the group of seven transitions Fg=3 - Fe=5 is completely resolved and is located at the high frequency wing of Fg=3 - Fe=2,3,4 transitions. The applied theoretical model very well describes the experimental curves.

physics.atom-ph↗

arXiv2008

Measurement of diffusion coefficients of francium and rubidium in yttrium based on laser spectroscopy

We report the first measurement of the diffusion coefficients of francium and rubidium ions implanted in a yttrium foil. We developed a methodology, based on laser spectroscopy, which can be applied to radioactive and stable species, and allows us to directly take record of the diffusion time. Francium isotopes are produced via fusion-evaporation nuclear reaction of a 100 MeV 18-O beam on a Au target at the Tandem XTU accelerator facility in Legnaro, Italy. Francium is ionized at the gold-vacuum interface and Fr+ ions are then transported with a 3 keV electrostatic beamline to a cell for neutralization and capture in a magneto-optical trap (MOT). A Rb+ beam is also available, which follows the same path as Fr+ ions. The accelerated ions are focused and implanted in a 25 um thick yttrium foil for neutralization: after diffusion to the surface, they are released as neutrals, since the Y work function is lower than the alkali ionization energies. The time evolution of the MOT and the vapor fluorescence signals are used to determine diffusion times of Fr and Rb in Y as a function of temperature.

physics.atom-ph↗

arXiv2008

High-Precision Measurement of the Laser-Trapping Frequencies for $^{209,210,211}$Fr Atoms

We present the accurate measurement of the frequency of the $7S-7P$ laser-trapping transition for three francium isotopes. Our approach is based on an interferometric comparison to deduce the unknown laser frequency from a secondary laser frequency-standard. After careful investigation of systematics, with samples of about 100 atoms the final accuracy reaches 8 MHz, an order of magnitude better than the best previous measurement for $^{210}$Fr, and opens the way to improved tests of the theoretical computation of Fr atomic structure.

physics.atom-ph↗

arXiv2007

Saturated absorption spectroscopy: elimination of crossover resonances by use of a nanocell

It is demonstrated that velocity selective optical pumping/saturation resonances of reduced absorption in a Rb vapor nanocell with thickness \textit{L=} $λ$, 2$λ$, and 3$λ$ (resonant wavelength $λ$ = 780 nm) allow the complete elimination of crossover (CO) resonances. We observe well pronounced resonances corresponding to the F$_{g}=3$ $\to $ F$_{e}=2,3,4$ hyperfine transitions of the $^{85}$Rb D$_{2}$ line with linewidths close to the natural width. A small CO resonance located midway between F$_{g}=3$ $\to $ F$_{e}=3$ and F$_{g}=3$ $\to$ F$_{e}=4$ transitions appears only for \textit{L} = 4$λ$. The D$_{2}$ line ($λ$ = 852 nm) in a Cs nanocell exhibits a similar behavior. From the amplitude ratio of the CO and VSOP resonances it is possible to determine the thickness of the column of alkali vapor in the range of 1 - 1000 $μ$m. The absence of CO resonances for nanocells with $L \sim λ$ is attractive for frequency reference application and for studying transitions between Zeeman sublevels in external magnetic fields.

physics.class-ph↗

arXiv1995

Ultrashort Laser-pulse Diagnostics for Detection of Ordering within an Ion beam

A novel diagnostic method to detect ordering within one-dimensional ion beams in a storage ring is presented. The ions are simultaneously excited by a ultrashort pulsed laser ($\simeq 1$ ps) at two different locations along the beam and fluorescence is detected by a group of four photo-multipliers. Correlation in fluorescence signals is a firm indication that the ion beam has an ordered structure.

acc-phys↗

arXiv1995

Stroboscopic Laser Diagnostics for Detection of Ordering in One-Dimensional Ion beam

A novel diagnostic method for detecting ordering in one-dimensional ion beams is presented. The ions are excited by a pulsed laser at two different positions along the beam and fluorescence is observed by a group of four photomultipliers. Correlation in fluorescence signals is firm indication that the ion beam has an ordered structure.

acc-phys↗