59608168
Impact of Ion Clearing Electrodes on Beam Dynamics in DAΦNE
Presently clearing electrodes are being considered as a possible cure of e-cloud driven problems in existing and future colliders. ``Invisible'' electrodes, made of a thin highly resistive layer pasted on a dielectric plate, have been proposed as one of design solutions for the e-cloud clearing. For the first time such electrodes were successfully used in the Electron-Positron Accumulator (EPA) of LEP. Similar electrodes had been used for a long time for ion clearing purposes in the DAΦNE electron ring. Theoretical considerations and experimental measurements at DAΦNE have revealed a substantial contribution of the Ion Clearing Electrodes (ICE) to the machine broad-band impedance giving rise to several harmful effects degrading the collider performance. In this paper we discuss the impact of the electrodes on DAΦNE beam dynamics, show the results of ICE wake field and impedance calculations and compare them with available experimental data. We also describe the procedure of ICE removal from the wiggler sections of the electron ring that has resulted in remarkable improvements in terms of beam dynamics and geometric luminosity.
59520419
CTF3 prototypes: design, tests and measurements
The high efficiency in the 30 GHz power production is maintained if the beam quality is preserved along the rings and the transfer lines of the CLIC Test Facility (CTF3) compressor system. The energy loss and energy spread, caused by vacuum chamber components coupling impedance and by coherent synchrotron radiation (CSR) emission, must be minimized. The magnetic layouts of the first ring of the compressor system, called delay loop (DL) and of the transfer line between the Linac and DL are presented. Tests and measurements on several vacuum chamber components prototypes are reported. The 3 GHz RF deflectors, that will provide the injection in the combiner ring, have been studied, realized, tested, installed and successfully used in the first interlaced bunch trains injection in the CTF3 preliminary phase. A standing wave 1.5 GHz RF deflector for injection into the delay loop is proposed.
49383196
MEASUREMENTS ON AN A / D INTERFACE USED IN THE POWER SUPPLY CONTROL SYSTEM OF THE MAIN DIPOLES OF CNAO
CNAO, the Italian Centre of Oncological Hadrontherapy located in Pavia, is in its final step of construction and is about to be fully operative. It is based on a synchrotron that can accelerate protons up to 250 MeV and carbon ions up to 400 MeV/u for the treatment of patients. In this paper we describe an A/D interface, used in the power supply control system of the synchrotron main dipoles, called B-Train. The field is measured in a dedicated dipole connected in series with the sixteen ones of the synchrotron and is then fed back to the power supply. The field is obtained integrating and digitizing the voltage induced on a pickup coil inserted in the gap of the seventeenth dipole. The A/D interface under study is based on a 64-channel current to frequency converter ASIC, in CMOS 0.35 μm technology, followed by a counter and uses a recycling integrator technique. The digital signal obtained is then used to generate a feedback signal for control system of the dipoles power supply. We present the electronic structure, the lab measurements and the behaviour for various setups of the A/D interface described.
16688402
Status of the SPARX FEL project
The SPARX project consists in an X-ray-FEL facility jointly supported by MIUR (Research Department of Italian Government), Regione Lazio, CNR, ENEA, INFN and Rome University Tor Vergata. It is the natural extension of the ongoing activities of the SPARC collaboration. The aim is the generation of electron beams characterized by ultra-high peak brightness at the energy of 1 and 2 GeV, for the first and the second phase respectively. The beam is expected to drive a single pass FEL experiment in the range of 13.5-6 nm and 6-1.5 nm, at 1 GeV and 2 GeV respectively, both in SASE and SEEDED FEL configurations. A hybrid scheme of RF and magnetic compression will be adopted, based on the expertise achieved at the SPARC high brightness photoinjector presently under commissioning at Frascati INFNLNF Laboratories. The use of superconducting and exotic undulator sections will be also exploited. In this paper we report the progress of the collaboration together with start to end simulation results based on a combined scheme of RF compression techniques.
107812339
Commissioning Status of the CTF3 Delay Loop
The CLIC Test Facility CTF3, built at CERN by an international collaboration, aims at demonstrating the feasibility of the CLIC scheme of multi-TeV electronpositron linear collider by 2010. In particular, one of the main goals is to study the generation of high-current electron pulses by interleaving bunch trains in delay lines and rings using transverse RF deflectors. This will be done in the 42 m long delay loop, built under the responsibility of INFN/LNF, and the 84 m long combiner ring that will follow it. The delay loop installation was completed and its commissioning started at the end of 2005. In this paper the commissioning results are presented, including the first tests of beam recombination.
126277943
The SPARC project: a high-brightness electron beam source at LNF to drive a SASE-FEL experiment
Abstract The Project Sorgente Pulsata e Amplificata di Radiazione Coerente (SPARC), proposed by a collaboration among ENEA–INFN–CNR–Universita’ di Tor Vergata–INFM–ST, was recently approved by the Italian Government and will be built at LNF. The aim of the project is to promote an R&D activity oriented to the development of a coherent ultra-brilliant X-ray source in Italy. This collaboration has identified a program founded on two main issues: the generation of ultra-high peak brightness electron beams and of resonant higher harmonics in the SASE-FEL process, as presented in this paper.
16688202
Strong gravitational field light deflection in binary systems containing a collapsed star
Large light deflection angles are produced in the strong gravitational field regions around neutron stars and black holes. In the case of binary systems, part of the photons emitted from the companion star towards the collapsed object are expected to be deflected in the direction of the earth. Based on a semi-classical approach we calculate the characteristic time delays and frequency shifts of these photons as a function of the binary orbital phase. The intensity of the strongly deflected light rays is reduced by many orders of magnitude, therefore making the observations of this phenomenon extremely difficult. Relativistic binary systems containing a radio pulsar and a collapsed object are the best available candidates for the detection of the strongly deflected photons. Based on the accurate knowledge of their orbital parameters, these systems allow to predict accurately the delays of the pulses along the highly deflected path, such that the sensitivity to very weak signals can be substantially improved through coherent summation over long time intervals. We discuss in detail the cases of PSR 1913+16 and PSR 1534+12 and find that the system geometry is far more promising for the latter. The observation of the highly deflected photons can provide a test of general relativity in an unprecedented strong field regime as well as a tight constraint on the radius of the collapsed object.