NUCLEAR COLLECTIVE MODES AT FINITE TEMPERATURE AS A PROBE OF NUCLEAR STRUCTURE AND DYNAMICS

The framework of this Thesis is the study of nuclear structure and reaction dynamics through gamma-spectroscopy measurements in fusion-evaporation reactions. The gamma emission associated with the Dynamical Dipole (DD) mode and the Giant Dipole Resonance (GDR) is a very good tool to study the role of the nuclear interaction in compound-nucleus formation and decay as is discussed in this Thesis with two examples, namely a measurement of DD gamma emission in a N/Z-asymmetric fusion reaction and of GDR decay from a self-conjugate compound nucleus (CN). In fact, DD oscillation is ruled by the symmetry term of the nuclear force that drives the proton and neutron densities toward a configuration which minimizes the potential energy of the system. The hindrance of isospin-forbidden GDR gamma decay from a self-conjugate CN is due to a partial restoration of isospin symmetry at high nuclear temperature, since the excited compound-nucleus lifetime is too short for the relatively weak Coulomb interaction to mix states with different isospin. Two experiments are discussed, both performed at Laboratori Nazionali di Legnaro with the GARFIELD-HECTOR array. This array includes a gamma detector with good efficiency and timing performance, a detector for evaporation residues in order to select the fusion-evaporation channel and a detector for light charged particles accounting for the other components of the decay. The first one is the HECTOR array of BaF2 scintillators, the second one is a group of PHOSWICH scintillators and the third one is the GARFIELD DE-E array of microstrip gas chambers coupled to CsI scintillators. The results obtained with the N/Z-asymmetric 16O+116Sn reaction at beam energies of 8.1, 12 and 15.6 MeV/u display a \u201crise and fall\u201d trend of the Dynamical Dipole multiplicity as a function of beam energy, with the maximum at beam energy of 12 MeV/u. Data are compared with theoretical calculations of gamma emission performed applying the Bremsstrahlung formula to the dipole oscillation obtained with a Stochastic Mean Field approach based on Boltzmann-Nordheim-Vlasov transport equation. Theoretical calculations display a rather flat dependence on beam energy which calls for further investigations. For the analysis of isospin mixing in 80Zr* a modified version of standard Statistical Model calculation has been used, which includes the appropriate isospin physics in CN population and decay. Theoretical models predict a decrease of isospin mixing with increasing CN temperature and existing measurements confirm a strong hindrance of first-step gamma decay from the self-conjugate CN due to the selection rules for E1 transitions forbidding I=0 to I=0 transitions. The degree of isospin mixing obtained for 80Zr* is consistent with the systematics at finite temperature and with the expected temperature dependence

The role of inflammation in patients with intraductal mucinous neoplasm of the pancreas and in those with pancreatic adenocarcinoma

Background: There are very few data regarding inflammation in patients with intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. Aim: To evaluate the circulating concentrations of placental growth factor (PlGF), transforming growth factor-alpha (TGF-\u3b1), transforming growth factor-beta 1 (TGF-\u3b21), tumour necrosis factor receptor 1 (TNF-R1) and matrix metalloproteinase-2 (MMP-2) in patients with IPMNs and in those with pancreatic adenocarcinomas. Patients and Methods: Sixty-nine patients were enrolled: 23 (33.3%) had IPMNs and 46 (66.7%) had histologically confirmed pancreatic adenocarcinomas. Thirteen healthy subjects were also studied. PlGF, TGF-\u3b1, TGF-\u3b21, TNF-R1 and MMP-2 were determined using commercially available kits. Results: TNF-R1 (p=0.003) was the only protein significantly different among the three groups. Conclusion: Serum TNF-R1 was elevated in patients with IPMNs and in those with pancreatic adenocarcinomas, suggesting a high apoptotic activity in both groups of patients studied

Impact of semi-solid formulations on skin penetration of iron oxide nanoparticles

Background: This work aimed to provide useful information on the incidence of the choice of formulation in semi-solid preparations of iron-oxide nanoparticles (IONs). The appropriate analytical methods to assess the IONs physical stability and the effect of the semi-solid preparations on IONs human skin penetration were discussed. The physical stability of IONs (Dh = 31 \ub1 4 nm; \u3b6 = -65 \ub1 5 mV) loaded in five semi-solid preparations (0.3% w/v), namely Carbopol gel (CP), hydroxyethyl cellulose gel (HEC), carboxymethylcellulose gel (CMC), cetomacrogol cream (Cet) and cold cream was assessed by combining DLS and low-field pulsed NMR data. The in vitro penetration of IONs was studied using human epidermis or isolated stratum corneum (SC). Results: Reversible and irreversible IONs aggregates were evidenced only in HEC and CMC, respectively. IONs diffused massively through SC preferentially by an intercellular pathway, as assessed by transmission electron microscopy. The semi-solid preparations differently influenced the IONs penetration as compared to the aqueous suspension. Cet cream allowed the highest permeation and the lowest retained amount, while cold cream and CP favored the accumulation into the skin membrane. Conclusion: Basic cutaneous semi-solid preparations could be used to administer IONs without affecting their permeation profile if they maintained their physical stability over time. This property is better discriminated by low-field pulsed NMR measurements than the commonly used DLS measurements

Population of neutron-rich nuclei around 48ca with deep inelastic collisions

The deep inelastic reaction 48Ca+64Ni at 6 MeV/A has been studied using the CLARA–PRISMA setup. Angular distributions for pure elastic scattering and total cross-sections of the most relevant transfer channels have been measured. The experimental results are compared with predictions from a semiclassical model, showing good agreement for the presently analyzed few neutrons transfer channels. The decay of the most intense reaction products has also been studied, giving indications of the population of states with very short lifetimes.Gadea Raga, Andrés, [email protected]

High-spin states in 212Po above the α-decaying (18+) isomer

The nucleus Po has been produced through the fragmentation of a U primary beam at 1 GeV/nucleon at GSI, separated with the FRagment Separator, FRS, and studied via isomer γ-decay spectroscopy with the RISING setup. Two delayed previously unknown γ rays have been observed. One has been attributed to the E3 decay of a 21 isomeric state feeding the α-emitting 45-s (18) high-spin isomer. The other γ-ray line has been assigned to the decay of a higher-lying 23 metastable state. These are the first observations of high-spin states above the Po (18) isomer, by virtue of the selectivity obtained via ion-by-ion identification of U fragmentation products. Comparison with shell-model calculations points to shortfalls in the nuclear interactions involving high-j proton and neutron orbitals, to which the region around Z∼100 is sensitive.This work was partially supported by the Ministry of Science, and Generalitat Valenciana, Spain, under the Grants SEV-2014-0398, FPA2017-84756-C4, PID2019-104714GB-C21, PROMETEO/2019/005 and by the EU FEDER funds. The support of the UK STFC, of the Swedish Research Council under Contract No. 2008-4240 and No. 2016-3969 and of the DFG (EXC 153) is also acknowledged. The experimental activity has been partially supported by the EU under the FP6-Integrated Infras-tructure Initiative EURONS, Contract No. RII3-CT-2004-506065 and FP7-Integrated Infrastructure Initiative ENSAR, Grant No. 262010

Reaction dynamics and nuclear structure studies via deep inelastic collisions with heavy-ions: spin and parity assignment in (49)Ca

The population and gamma decay of neutron rich nuclei around 48Ca has been measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using deep-inelastic collisions (DIC) on 64Ni, at an energy approximately twice the Coulomb barrier. The reaction properties of the main products are investigated, focusing on total cross sections and angular distributions both integrated in energy and associated to the population of specific excited states. Gamma spectroscopy studies are also performed, giving evidence, for the first time in transfer reactions with heavy ions, of a large spin alignment ( 3c70%), perpendicular to the reaction plane. This makes possible the use of angular distributions and polarization measurements to firmly establish the spin and parity of excited states populated in nucleon transfer channels, as in the case of 49Ca, where candidates for particle-core coupling are investigated. Both reaction and gamma spectroscopy studies demonstrate the relevance of DIC with heavy ions for a detailed investigation of moderately neutron rich systems

Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC-2020 March 27 17:00 UTC). We conduct two independent searches: A generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate. © 2022. The Author(s). Published by the American Astronomical Society

Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society