High Luminosity Issues for DAPhNE Upgrade

We give an overview of presentations and discussions during the Accelerator Working Group Session dedicated to High Luminosity Issues for a future upgrade of the Frascati e+e- Phi-Factory DAPhNE at the Workshop "e+e- in the 1-2 GeV range: Physics and Accelerator Prospects" held at Alghero (Italy) on 10-13 September 2003.Comment: Invited talk at the Workshop on e+e- in the 1-2 GeV range, Alghero, Italy, September 2003 (eConf c0309101

A Review of New Manifestations of Collective Effects

The design of high performance `factories', large hadron colliders and synchrotron light sources calls for a large number of high intensity bunches. This imposes feedback systems and a tight impedance budget to control conventional instabilities, some of which are differently emphasised depending on the ongoing evolution of beam parameters. Ion trapping, for example, is no longer reported as a problem for the new generation of very low emittance electron storage rings. However new mechanisms appear, such as the fast ion instability for electron beams and the build-up of electron clouds for positron or proton beams. We review these new manifestations of collective phenomena, essentially related to the single-pass interaction of a bunch train with foreign or `gaijin' particles, and discuss their dependence on several machine parameters such as bunch intensity and spacing. We also summarise possible cures and positive as well as negative experimental evidence in existing accelerators

Electron Cloud in the LHC

A theoretical and experimental crash program has been set up at CERN to investigate electron cloud effects in the LHC. In particular, I report about recent estimates of the critical secondary-emission yield, versus bunch population and bunch spacing, and ongoing multipacting tests with a coaxial resonator in a strong magnetic field

Resistive wall impedance as derivative of the electric capacitance for a beam pipe of arbitrary cross section

We derive a general formula expressing the resistive wall impedance in the ultrarelativistic limit for a beam pipe of arbitrary cross section through the 'normal derivative' of its electric capacitance. An application to the case of rectangular cross secrion yields a closed form of expression of the corresponding longitudinal impedance in terms of elliptic integrals

Medical implantable devices for the controlled release of anti-TGF-beta1 in the repair of peripheral nerve injuries

The development of novel bioartificial nerve grafts which release soluble therapeutic agents, shows great promises guiding the extension of the injured axons and optimizing and improving the degree and specificity of neural outgrowth. The TGF-â family cytokines are polypeptides involved in pathogenesis of neuropathies during nerve lesion. In particular, studies carried out on TGF-â1 have demonstrated its key-role as a humoral stimulus in scar formation. The use of neutralising antibodies to this pro-fibrotic factor, incorporated and released by medical devices, could be potentially useful to get improved results in nerve repair. The aim of this study was to characterise the uptake and release of antibodies, structurally no different from the anti-TGFâ1 specific ones, by innovative constructs based on the use of biodegradable and biocompatible compounds with which to support and improve peripheral nerve repair