The VELO High Voltage System Control Software

This note describes the VELO high voltage control software. The implementation of its structure as a PVSS Finite State Machine is emphasized. The main error conditions that may occur during operation is also discussed. The VELO HV software conforms to the specification of the VELO

A new generation photodetector for astroparticle physics: the VSiPMT

The VSiPMT (Vacuum Silicon PhotoMultiplier Tube) is an innovative design we proposed for a revolutionary photon detector. The main idea is to replace the classical dynode chain of a PMT with a SiPM (G-APD), the latter acting as an electron detector and amplifier. The aim is to match the large sensitive area of a photocathode with the performance of the SiPM technology. The VSiPMT has many attractive features. In particular, a low power consumption and an excellent photon counting capability. To prove the feasibility of the idea we first tested the performance of a special non-windowed SiPM by Hamamatsu (MPPC) as electron detector and current amplifier. Thanks to this result Hamamatsu realized two VSiPMT industrial prototypes. In this work, we present the results of a full characterization of the VSiPMT prototype

Peptide-chelating agent conjugate for selective targeting of somatostatin receptor type1: Synthesis and characterization

Previously reported results suggest that the analogue of the somatostatin des-AA 1,2,5[D-Trp 8,IAmp 9]-somatostatin (CH-275) peptide bearing chelating agents able to coordinate radioactive metals could be used for scintigraphic imaging of tumor lesions overexpressing sstr1. An efficient synthetic procedure for the preparation of the somatostatin analogue CH-275 and its conjugate DTPAGlu-Gly-CH-275, bearing the chelating agent DTPAGlu (DTPAGlu = N,N-bis[2-[bis(carboxy-ethyl)amino]ethyl]-L-glutamic acid) on the N-terminus, by solid-phase peptide synthesis and 9-flourenymethyoxycarbonyl (Fmoc) chemistry, is here reported. Rapid and efficient labeling of DTPAGlu-Gly-CH-275 was achieved by addition of IIIIn(III) to the compound. Typical yields were greater than 97% as determined by reversed phase high performance liquid chromatography (HPLC) at specific activities in the range 4-9 GBq/μmol (100-250 Ci/mmol). A preliminary biological assay of the binding ability of IIIIn-DTPAGlu-Gly-CH-275 indicates, however, that the labeled compound does not display any specific interaction with somatostatin sstrl receptors in the tested cell lines. To confirm this unexpected negative result, competition binding experiments were carried out, in which fixed tracer amounts of the 125!-labeled somatostatin-14 were incubated with the receptor-expressing cells in the presence of DTPAGlu-Gly-CH-275 or CH-275 at concentrations ranging from 10 -10 to 10 -3 M. While CH-275 shows a IC 50 of 80 nM similar to that already found in displacement experiments on CHO-Kl sstrl-transfected cells, DTPAGlu-Gly-CH-275 displays instead very low or negligible affinity towards this receptor. The NMR solution characterization indicates that the presence of DTPAGlu does not influence the conformational and chemical features of the peptide moiety, thus suggesting that the loss in binding activity should be due to steric hindrance of either the chelating agent DTPAGlu or its indium comple

The VSiPMT project

Photon detection is a key factor to study many physical processes in several areas of fundamental physics research. Focusing the attention on photodetectors for particle astrophysics, the future experiments aimed at the study of very high-energy or extremely rare phenomena (e.g. dark matter, proton decay, neutrinos from astrophysical sources) will require additional improvements in linearity, gain, quantum efficiency and single photon counting capability. To meet the requirements of this class of experiments, we propose a new design for a modern hybrid photodetector: the VSiPMT (Vacuum Silicon PhotoMultiplier Tube). The idea is to replace the classical dynode chain of a PMT with a SiPM, which therefore acts as an electron detector and amplifier. The aim is to match the large sensitive area of a photocathode with the performances of the SiPM technology. We now present the preliminary study we are performing to realize a 3-inches VSiPMT prototype

The Transmissibility of Highly Pathogenic Avian Influenza in Commercial Poultry in Industrialised Countries

BACKGROUND: With the increased occurrence of outbreaks of H5N1 worldwide there is concern that the virus could enter commercial poultry farms with severe economic consequences. METHODOLOGY/PRINCIPAL FINDINGS: We analyse data from four recent outbreaks of highly pathogenic avian influenza (HPAI) in commercial poultry to estimate the farm-to-farm reproductive number for HPAI. The reproductive number is a key measure of the transmissibility of HPAI at the farm level because it can be used to evaluate the effectiveness of the control measures. In these outbreaks the mean farm-to-farm reproductive number prior to controls ranged from 1.1 to 2.4, with the maximum farm-based reproductive number in the range 2.2 to 3.2. Enhanced bio-security, movement restrictions and prompt isolation of the infected farms in all four outbreaks substantially reduced the reproductive number, but it remained close to the threshold value 1 necessary to ensure the disease will be eradicated. CONCLUSIONS/SIGNIFICANCE: Our results show that depending on the particular situation in which an outbreak of avian influenza occurs, current controls might not be enough to eradicate the disease, and therefore a close monitoring of the outbreak is required. The method we used for estimating the reproductive number is straightforward to implement and can be used in real-time. It therefore can be a useful tool to inform policy decisions

Nanoscale modulation of the density of states at the conducting interface between LaAlO3 and SrTiO3 band insulators

The appearance of high-mobility electrons at the LaAlO3/SrTiO3 interface has raised strong interest in the material science community and a lively debate on the origin of the phenomenon. A possible explanation is an electronic reconstruction, realizing a transfer of electrons to SrTiO3 at the interface, thereby avoiding the build-up of excessive Coulomb energy as described by the "polarization catastrophe" associated with the alternating polar layers of the LaAlO3 film. Theoretical models predict that electrons are transferred into titanium 3d(xy) interface states and, in the presence of strong correlations, generate a charge and orbital order. Here we provide experimental evidence that at room temperature the local density of states of the LaAlO3/SrTiO3 conducting interface is modulated at the nanoscale in a short-range quasiperiodic pattern, which is consistent with the appearance of an orbital (short-range) order. This result, together with the splitting of the 3d states, confirms that an electronic reconstruction drives the functional properties of the LaAlO3/SrTiO3 oxide interface. The short-range superstructure does not fully agree with the theoretical predictions. Thus, further experimental and theoretical investigations are required to understand the electronic properties of the 2D electron system realised at the LaAlO3/SrTiO3 interface

Performance of the LHCb muon system

The performance of the LHCb Muon system and its stability across the full 2010 data taking with LHC running at ps = 7 TeV energy is studied. The optimization of the detector setting and the time calibration performed with the first collisions delivered by LHC is described. Particle rates, measured for the wide range of luminosities and beam operation conditions experienced during the run, are compared with the values expected from simulation. The space and time alignment of the detectors, chamber efficiency, time resolution and cluster size are evaluated. The detector performance is found to be as expected from specifications or better. Notably the overall efficiency is well above the design requirementsComment: JINST_015P_1112 201

Symmetry breaking at the (111) interfaces of SrTiO3{_3} hosting a 2D-electron system

We used x-ray absorption spectroscopy to study the orbital symmetry and the energy band splitting of (111) LaAlO${_3}$/SrTiO${_3}$ and LaAlO${_3}$/EuTiO${_3}$/SrTiO${_3}$ heterostructures, hosting a quasi two-dimensional electron system (q2DES), and of a Ti-terminated (111) SrTiO${_3}$ single crystal, also known to form a q2DES at its surface. We demonstrate that the bulk tetragonal Ti-3d D${_4}$${_h}$ crystal field is turned into trigonal D${_3}$${_d}$ crystal field in all cases. The symmetry adapted a${_1}$${_g}$ and e${^\pi_g}$ orbitals are non-degenerate in energy and their splitting, \Delta, is positive at the bare STO surface but negative in the heterostructures, where the a${_1}$${_g}$ orbital is lowest in energy. These results demonstrate that the interfacial symmetry breaking induced by epitaxial engineering of oxide interfaces has a dramatic effect on their electronic properties, and it can be used to manipulate the ground state of the q2DES.Comment: 6 pages article, plus 5 pages supplementary informatio

Observation of a two-dimensional electron gas at the surface of annealed SrTiO3 single crystals by scanning tunneling spectroscopy

Scanning tunneling spectroscopy suggests the formation of a two dimensional electron gas (2DEG) on the TiO2 terminated surface of undoped SrTiO3 single crystals annealed at temperature lower than 400 {\deg}C in ultra high vacuum conditions. Low energy electron diffraction indicates that the 2D metallic SrTiO3 surface is not structurally reconstructed, suggesting that non-ordered oxygen vacancies created in the annealing process introduce carriers leading to an electronic reconstruction. The experimental results are interpreted in a frame of competition between oxygen diffusion from the bulk to the surface and oxygen loss from the surface itself.Comment: 9 pages, 3 figures, submitted to Physical Review