Measurement of the radiative capture cross section of the s-process branching points 204Tl and 171Tm at the n_TOF facility (CERN)

The neutron capture cross section of some unstable nuclei is especially relevant for s-process nucleosynthesis studies. This magnitude is crucial to determine the local abundance pattern, which can yield valuable information of the s-process stellar environment. In this work we describe the neutron capture (n,γ) measurement on two of these nuclei of interest, 204Tl and 171Tm, from target production to the final measurement, performed successfully at the n_TOF facility at CERN in 2014 and 2015. Preliminary results on the ongoing experimental data analysis will also be shown. These results include the first ever experimental observation of capture resonances for these two nuclei.

Evaluation of the Expression of Tissue DF-3 and MCA and the Corresponding Serum Values in Patients with Breast Carcinoma

Two specific monoclonal antibodies for breast tissue (DF3 and MCAb-12) and the corresponding tumor markers CA15-3 and MCA in serum have been evaluated in 50 patients with breast cancer and in 15 controls. The expression of these antigens in tissue was poorly correlated with the common prognostic parameters. Their presence in serum was associated with an altered distribution of the antigens in the cell. The expression of these antigens in tissue enables us to select patients for serological follow-up and to evaluate tumor differentiation from a functional point of view.

First Measurement of 72Ge(n, γ) at n_TOF

The slow neutron capture process (s-process) is responsible for producing about half of the elemental abundances heavier than iron in the universe. Neutron capture cross sections on stable isotopes are a key nuclear physics input for s-process studies. The 72Ge(n, γ) cross section has an important influence on production of isotopes between Ge and Zr during s-process in massive stars and therefore experimental data are urgently required. 72Ge(n, γ) was measured at the neutron time-of-flight facility n_TOF (CERN) for the first time at stellar energies. The measurement was performed using an enriched 72GeO2 sample at a flight path of 185m with a set of liquid scintillation detectors (C6D6). The motivation, experiment and current status of the data analysis are reported.

7Be(n,p) cross section measurement for the Cosmological Lithium Problem at the n_TOF facility at CERN

One of the most puzzling problems in Nuclear Astrophysics is the "Cosmological Lithium Problem", i.e the discrepancy between the primordial abundance of 7Li observed in metal poor halo stars [1], and the one predicted by Big Bang Nucleosynthesis (BBN). One of the reactions that could have an impact on the problem is 7Be(n,p)7Li. Despite of the importance of this reaction in BBN, the cross-section has never been directly measured at the energies of interest for BBN. Taking advantage of the innovative features of the second experimental area at the n_TOF facility at CERN, an accurate measurement of 7Be(n,p) cross section has been recently performed at n_TOF, with a pure 7Be target produced by implantation of a 7Be beam at ISOLDE. The experimental procedure, the setup used in the measurement and the results obtained so far will be here presented.

^{7}Be(n,α)^{4}He Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN

The energy-dependent cross section of the ^{7}Be(n,α)^{4}He reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of ^{7}Be and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure ^{7}Be, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-^{7}Be-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.

Silicon detectors for monitoring neutron beams in n-TOF beamlines

During 2014, the second experimental area (EAR2) was completed at the n-TOF neutron beam facility at CERN (n-TOF indicates neutron beam measurements by means of time of flight technique). The neutrons are produced via spallation, by means of a high-intensity 20 GeV pulsed proton beam impinging on a thick target. The resulting neutron beam covers the energy range from thermal to several GeV. In this paper, we describe two beam diagnostic devices, both exploiting silicon detectors coupled with neutron converter foils containing (6)Li. The first one is based on four silicon pads and allows monitoring of the neutron beam flux as a function of the neutron energy. The second one, in beam and based on position sensitive silicon detectors, is intended for the reconstruction of the beam profile, again as a function of the neutron energy. Several electronic setups have been explored in order to overcome the issues related to the gamma flash, namely, a huge pulse present at the start of each neutron bunch which may blind the detectors for some time. The two devices were characterized with radioactive sources and also tested at the n-TOF facility at CERN. The wide energy and intensity range they proved capable of sustaining made them attractive and suitable to be used in both EAR1 and EAR2 n-TOF experimental areas, where they became immediately operational.

Efficacy and safety of a salvage regimen based on tipranavir, enfuvirtide and three nucleoside analogues in HIV1 infected patients with clinical progression: 96-week evaluation

In recent years, novel antiretroviral drugs have become available for multi-experienced HIV-infected patients with limited options. We enrolled seven advanced HIV-patients, failing multiple previous HAART regimens, in virological failure on their current HAART regimen and showing recent clinical and immunological progression. All patients were prescribed a double-boosted tipranavir plus enfuvirtide based regimen, in addition to zidovudine, tenofovir and lamivudine for salvage therapy. To assess susceptibility to tipranavir, the tipranavir genotypic resistance score was calculated and two years later this was re-evaluated on an updated tipranavir genotypic score algorithm. At baseline, CD4 were 139/mcL (more or less 145), HIV-1 RNA was 822,700 cp/mL. All patients achieved HIV-1 RNA levels less than 400 cp/mL between 12 weeks and 24 weeks of observation; two reached less than 50 cp/mL during this period. At 48 weeks three patients had reached less than 50 cp/mL; three other patients had HIV RNA less than 200 cp/mL. At 72 and 96 weeks HIV viraemia was less than 50 cp/mL in six patients; CD4 T-cell counts 285/mcL (more o less 198). No AIDS-defining events were recorded. Adverse events did not need to stop or change HAART. Strong 3 NRTI backbone could help efficacy and durability, and frequent evaluations in complex patients can help to manage toxicity.