SPIRAL2 RFQ prototype - First results

JACoW web site MOPCH103International audienceThe SPIRAL2 RFQ is designed to accelerate either 5 mA deuteron beam (Q/A=1/2) or a 1 mA of q/A=1/3 particle up to 0.75 MeV/A at 88 MHz. It is a CW machine which has to show stable operation, provide the required availability and reduce losses to a minimum in order to minimize the activation constraints. Extensive modelisation was done to ensure a good vane position under RF. The prototype of this 4-vane RFQ was built and tested in INFN-LNS Catania and then in IN2P3-LPSC Grenoble. It allowed us to measure the vacuum quality, the RF field by X-ray measurements, the cavity displacement and the real vane displacement during the RF injection. Different techniques were used, including an innovative CCD measurement with a 0.8 μm precision. This paper outlines the different results

Measurement of thick target neutron yields generated by accelerated heavy ions

International audienceIn accelerator facilities, due to their high penetration through matter, neutrons emittedfrom the interaction of high intensity primary beams with thick targets represent a risk ofradiation hazards that needs to be well characterized. The objective of the ongoing TTNY(Thick Target Neutron Yields) experimental program at GANIL is to measure neutron yieldsgenerated by the interaction of heavy ions (12C to 208Pb, from 4 MeV/u to 95 MeV/u)with thick targets (natCu, natNb, natC). Double differential (angular and energy) secondaryneutron spectra are obtained using two techniques: the activation of thin foils and neutronToF measurements. Measurement results are compared to Monte-Carlo transport codes(PHITS and FLUKA) in order to benchmark the physics models implemented in the codesto take into account the wide range of nuclear reactions involved. The data collected duringthe experimental program will also allow improving these physics models. In addition, dataobtained with the niobium target (12C (95MeV/u), natNb) are of high interest for the safetystudies associated with the upgrade of the SPIRAL1 facility at GANIL since this beam andtarget combination is the one considered to evaluate the upper limit of neutron radiationhazards associated with the operation of the facility

Swapped-Domain Constructs of the Glycoprotein-41 Ectodomain Are Potent Inhibitors of HIV Infection

The conformational rearrangement of N-and C-heptad repeats (NHR, CHR) of the HIV-1 glycoprotein-41 (gp41) ectodomain into a trimer of hairpins triggers virus – cell fusion by bringing together membrane-spanning N- and C-terminal domains. Peptides derived from the NHR and CHR inhibit fusion by targeting a prehairpin intermediate state of gp41. Typically, peptides derived from the CHR are low nM inhibitors, while peptides derived from the NHR are low μM inhibitors. Here we describe the inhibitory activity of swapped domain gp41 mimics of the form CHR-loop-NHR, which were designed to form reverse hairpin trimers exposing NHR grooves. We observed low nM inhibition of HIV fusion in constructs that possessed the following properties: an extended NHR C-terminus, an exposed conserved hydrophobic pocket on the NHR, high helical content and trimer stability. Low nM activity was independent of CHR length. CD studies in membrane mimetic dodecylphosphocholine micelles suggested that bioactivity could be related to the ability of the inhibitors to interact with a membrane-associated prehairpin intermediate. The swapped domain design resolves the problem of unstable and weakly active NHR peptides, and suggests a different mechanism of action from that of CHR peptides in inhibition of HIV-1 fusion