Energy and angular momentum sharing in dissipative collisions

Primary and secondary masses of heavy reaction products have been deduced from kinematics and E-ToF measurements, respectively, for the direct and reverse collisions of 93Nb and 116Sn at 25 AMeV. Light charged particles have also been measured in coincidence with the heavy fragments. Direct experimental evidence of the correlation of energy-sharing with net mass transfer has been found using the information from both the heavy fragments and the light charged particles. The ratio of Hydrogen and Helium multiplicities points to a further correlation of angular momentum sharing with net mass transfer.Comment: 21 pages, 20 figures. Submitted to European Physics Journal

Particle and light fragment emission in peripheral heavy ion collisions at Fermi energies

A systematic investigation of the average multiplicities of light charged particles and intermediate mass fragments emitted in peripheral and semiperipheral collisions is presented as a function of the beam energy, violence of the collision and mass of the system. The data have been collected with the "Fiasco" setup in the reactions 93Nb+93Nb at 17, 23, 30, 38AMeV and 116Sn+116Sn at 30, 38AMeV. The midvelocity emission has been separated from the emission of the projectile-like fragment. This last component appears to be compatible with an evaporation from an equilibrated source at normal density, as described by the statistical code Gemini at the appropriate excitation energy. On the contrary, the midvelocity emission presents remarkable differences for what concerns both the dependence of the multiplicities on the energy deposited in the midvelocity region and the isotopic composition of the emitted light charged particles.Comment: 18 pages, 17 figures, Revtex

Absent ductus venosus: different perinatal outcome related to anatomy

Congenital absence of the ductus venosus (ADV) is a rare condition which can present with several anatomic settings and associated to congenital anomalies of other systems. Different clinical patterns in the fetus and the newborn can emerge therefore. We report two cases of ADV with opposite perinatal outcomes. Case #1. A 28 y.o. black woman came at 22 weeks’ gestation (GA) for mid-pregnancy evaluation. She showed polyhydramnion (amniotic fluid index (AFI)= 261mm) associated to normal cardiac anatomy and normal karyotype (46,XX). The enlarged umbilical vein (UV) showed a pulsatile pattern at echoDoppler with direct connection to the RA. A fistula between the UV and the iliac artery was evidenced by colorDoppler as well. Despite normal ventricular contractility (EF) and diastolic function (E/A ratio) at echocardiographic monitoring, fetal cardiac enlargement progressively occurred with mild pericardial effusion. At 28 GA placental detachment occurred and a female infant (BW 915g, <10°p) was born with severe perinatal asphyxia. The infant died at 5 hours of life from severe acidosis refractory to intensive care and resuscitation efforts. Postmortem evaluation confirmed the anatomic pattern and absence of the portal vein (PV) was demonstrated as well. Case #2. A 35 y.o. white woman was admitted to our tertiary care at 33 GA because of monolateral renal agenesis and unique umbilical artery. Despite ADV, mesocardia and mild cardiac enlargement the fetus was stable (normal diastole and contractility). The UV echoDoppler showed a normal flat pattern at the beginning of its abdominal course but it progressively became pulsatile as the UV run cephalad to the heart. The infant was born at 38 GA from a planned cesarean delivery (BW 3080g). The perinatal adaptation, karyotype and phenotype were normal. Echocardiography in the newborn showed normal diastole and contractility (E/A ratio, LVEF, LVDd). The associated congenital anomalies were confirmed. DISCUSSION. ADV is a rare anomaly in which perinatal prognosis is difficult to predict and clinical presentation can vary greatly due to the different patterns, i.e. fetal cardiac failure, associated congenital anomalies, polyhydramnion. We reported 2 cases of ADV with opposite clinical course. As it often occurs, case #2 was detected occasionally, late in pregnancy, with a good hemodynamic status despite some malformative features. The normal perinatal transition shifted the cardiovascular system to a setting which did not need any DV activity in regulating venous return and the neonatal course was asymptomatic. Conversely case #1 showed fetal hemodynamics impaired since the beginning of the 3rd trimester. Maybe this could be the consequence of a huge hemodynamic overload due to the presence of both ADV and veno-arterial fistulas emphasizing the diastolic overload of a direct connection of the UV to the RA. The PV was also absent and this has been decribed as being related to a negative prognosis. It is still difficult to completely understand why some fetuses can tolerate the missing function of the DV in regulating the systemic venous return while others do not. To monitorate fetal cardiac function by echoDoppler can be helpful but it is not a standard yet. So case-by-case detailed evaluation of complete anatomy and analysis of both diastole and contractility remains the better choice. Finally the Obstetrician will be mandatory as any modification in the course of pregnancy can be life-threatening due to the thin hemodynamic balance of these fetuses

Probing the statistical decay and alpha-clustering effects in 12c+12c and 14n+10b reactions

An experimental campaign has been undertaken at INFN Laboratori Nazionali di Legnaro, Italy, in order to progress in our understanding of the statistical properties of light nuclei at excitation energies above particle emission threshold, by measuring exclusive data from fusion-evaporation reactions. A first reaction 12C+12C at 7.9 AMeV beam energy has been measured, using the GARFIELD+Ring Counter experimental setup. Fusion-evaporation events have been exclusively selected. The comparison to a dedicated Hauser-Feshbach calculation allows us to give constraints on the nuclear level density at high excitation energy for light systems ranging from C up to Mg. Out-of-equilibrium emission has been evidenced and attributed both to entrance channel effects favoured by the cluster nature of reaction partners and, in more dissipative events, to the persistence of cluster correlations well above the 24Mg threshold for 6 alphas decay. The 24Mg compound nucleus has been studied with a new measurement 14N + 10B at 5.7 AMeV. The comparison between the two datasets would allow us to further constrain the level density of light nuclei. Deviations from a statistical behaviour can be analyzed to get information on nuclear clustering.Comment: 4 pages, 2 figures, Contribution to conference proceedings of the 25th International Nuclear Physics Conference (INPC 2013

First results on the 32S+40,48Ca reactions at 17.7 AMeV studied with GARFIELD setup at LNL

The 32S+40,48Ca systems at 17 A MeV have been characterized both for fusion and for peripheral events thanks to the GARFIELD setup, which covers a wide angular range and has high granularity; moreover, isotopic identification for forward emitted ions up to Z around 15 is obtained. The main evidences reported here concern pre-equilibrium emission, which was put into evidence in fusion-evaporation events, and isospin diffusion observed studying the average N/Z of the Quasi-Projectile as a function of the target isospin

GARFIELD + RCo Digital Upgrade: a Modern Set-up for Mass and Charge Identification of Heavy Ion Reaction Products

An upgraded GARFIELD + Ring Counter (RCo) apparatus is presented with improved performances as far as electronics and detectors are concerned. On one side fast sampling digital read out has been extended to all detectors, allowing for an important simplification of the signal processing chain together with an enriched extracted information. On the other side a relevant improvement has been made in the forward part of the setup (RCo): an increased granularity of the CsI(Tl) crystals and a higher homogeneity in the silicon detector resistivity. The renewed performances of the GARFIELD + RCo array make it suitable for nuclear reaction measurements both with stable and with Radioactive Ion Beams (RIB), like the ones foreseen for the SPES facility, where the Physics of Isospin can be studied.Comment: 13 pages, 19 figures - paper submitted to Eur. Phys. J.