C. De Martinis

ELIMED, MEDical and multidisciplinary applications at ELI-Beamlines

ELI-Beamlines is one of the pillars of the pan-European project ELI (Extreme Light Infrastructure). It will be an ultra high-intensity, high repetition-rate, femtosecond laser facility whose main goal is generation and applications of high-brightness X-ray sources and accelerated charged particles in different fields. Particular care will be devoted to the potential applicability of laser-driven ion beams for medical treatments of tumors. Indeed, such kind of beams show very interesting peculiarities and, moreover, laser-driven based accelerators can really represent a competitive alternative to conventional machines since they are expected to be more compact in size and less expensive. The ELIMED project was launched thanks to a collaboration established between FZU-ASCR (ELI-Beamlines) and INFN-LNS researchers. Several European institutes have already shown a great interest in the project aiming to explore the possibility to use laser-driven ion (mostly proton) beams for several applications with a particular regard for medical ones. To reach the project goal several tasks need to be fulfilled, starting from the optimization of laser-target interaction to dosimetric studies at the irradiation point at the end of a proper designed transport beam-line. Researchers from LNS have already developed and successfully tested a high-dispersive power Thomson Parabola Spectrometer, which is the first prototype of a more performing device to be used within the ELIMED project. Also a Magnetic Selection System able to produce a small pencil beam out of a wide energy distribution of ions produced in laser-target interaction has been realized and some preliminary work for its testing and characterization is in progress. In this contribution the status of the project will be reported together with a short description of the of the features of device recently developed.

The SPARC/X SASE-FEL Projects

SPARC and SPARX are two different initiatives toward an Italian Free Electron Laser ~FEL! source operating in the Self Amplified Spontaneous Emission ~SASE! mode, in which several national research institutions are involved. SPARC is a high gain FEL project devoted to provide a source of visible and VUV radiation while exploiting the SASE mechanism. An advanced Photo-Injector system, emittance compensating RF-gun plus a 150 MeV Linac, will inject a high quality e-beam into the undulator to generate high brilliance FEL radiation in the visible region at the fundamental wavelength, ~;500 nm!. The production of flat top drive laser beams, high peak current bunches, and emittance compensation scheme will be investigated together with the generation of higher harmonic radiation in the VUV region. SPARX is the direct evolution of such a high gain SASE FEL toward the 13.5 and 1.5 nm operating wavelengths, at 2.5 GeV. To get the required value for the bunch peak current, Ipeak ’ 2.5 kA, the “hybrid” scheme, RF-compression stage plus magnetic chicane, is analyzed and compared with the more standard double stage of magnetic compression. The two options are reviewed considering the tolerance to the drive laser pulse phase jitter.

Displacement and emission currents from PLZT 8/65/35 and 4/95/5 excited by a negative voltage pulse at the rear electrode

Abstract It is shown that nonprepoled PLZT ceramics, both in ferroelectric and antiferroelectric phase, emit intense current bursts when a negative exciting voltage is applied to the rear surface of the cathode. The spontaneous polarization induced in the bulk by applying the field through the cathode disk, creates a sheet of negative charge on the diode boundary of the ferroelectric. This, in turn, induces such a high electric field at the diode dielectric surface that electrons are ejected out from the ceramic surface into the vacuum. The coherent behaviour of the displacement and emitted current shows clearly that the emission is due to a variation of spontaneous polarization. A second effect generated by the application of the high voltage pulse at the rear side is the formation of a surface plasma. Applying a positive voltage to the anode, electrons are readily transferred through the diode gap.

The Milan Superconducting Cyclotron Project

Design work on a superconducting cyclotron started in Milan in 1975, and a detailed analysis of 1all major aspects of theproject was completed in 1976 . Meanwhile a 1:6 scale superconducting model magnet was built and successfully operated toward the end of 19772. Lack of funding prevented the continuation of the project in the following years, till about fall 1980. In recent months the Italian National Institute for Nuclear Physics (I.N.F.N.) has authorized and funded the construction of the machine, which is now underway at the University of Milan. The machine design has considerably evolved in the past year or so, both in terms of expected performances and engineering aspects. It is the purpose of this paper to rewiew the main characteristics of the accelerator and to update the status of the project.

Model Magnet for the Proposed Superconducting Cyclotron at the University of Milan

A project for a superconducting cyclotron for heavy ions has been under study for a couple of years at the Cyclotron Laboratory of the University of Milan. The machine is conceived as a booster for a 16 MV Tandem to be installed at the Laboratories of Legnaro (Padua) of the Italian National Institute for Nuclear Physics (INFN). The K design value is approximately 540, thus allowing maximum energies between approximately 55 MeV/nucleon and approximately 14 MeV/nucleon for light and heavy ions respectively. Pole diameter is 1.8 m and maximum average field should be around 41 Kgauss, to be obtained by a total of 6.5 x 10/sup 6/ Aturns in the superconducting coils. At present a three spiral sector polar configuration is envisaged, with a 7 cm hill gap and 70 cm valley gap. Three dees, in the valleys, should provide a peak accelerating voltage of 100 kV, allowing a 3rd or 9th harmonic operation. While funding for the machine is still under discussion, a program centered upon the construction of a superconducting model magnet and a full scale rf model was started in 1976. The design features of the model magnet, whose construction is now completed, are reported.

A fast monitoring system for radiotherapeutic proton beams based on scintillating screens and a CCD camera

A facility in which a 62 MeV proton beam is employed in the radiotherapeutic treatment of several ocular disease has been active since March 2002 at Laboratori Nazionali del Sud. A fast and accurate quality control system of such beam has been designed and tested. The system consists of a scintillating screen mounted perpendicularly to the beam axis at a fixed distance and observed by a highly sensitive charge-coupled device camera. The basic idea is the possibility to obtain real time information about the relative spatial dose distribution delivered to tissue through the measurement of the light emission in the scintillating screen. A comparison with the presently used dosimetric system (a motorized silicon diode) that, in the future, will be replaced by the device introduced in this paper (if its experimental performance will be successful) has been carried out. The good capabilities of the system make it worthy of further investigations into its applicability in proton beams monitoring for radiotherapeutic treatments (i.e., reconstruction of depth dose distribution and beam monitoring during patient irradiation).

Model Studies for the Superconducting Cyclotron Project in Milan

of the project was completed in June 1976. In the meantime it was also decided that,pending approval and funding of the project, a model construction program would be helpful for i) getting the group acquainted with the problems connected with such a sophisticated machine, especially cryogenics and superconducting coil technology, ii) checking the theoretical calculations used for assessing magnetic fields and R.F. properties, and iii) ultimately reducing the time needed to build the machine in the near future.

A New Thomson Spectrometer for high energy laser-driven beams diagnostic

Thomson Spectrometers (TPs) are widely used for beam diagnostic as they provide simultaneous information on charge over mass ratio, energy and momentum of detected ions. A new TP design has been realized at INFN-LNS within the LILIA (Laser Induced Light Ion Acceleration) and ELIMED (MEDical application at ELI-Beamlines) projects. This paper reports on the construction details of the TP and on its experimental tests performed at PALS laboratory in Prague, with the ASTERIX IV laser system. Reported data are obtained with polyethylene and polyvinyl alcohol solid targets, they have been compared with data obtained from other detectors. Consistency among results confirms the correct functioning of the new TP. The main features, characterizing the design, are a wide acceptance of the deflection sector and a tunability of the, partially overlapping, magnetic and electric fields that allow to resolve ions with energy up to about 40 MeV for protons.

First operations of the LNS heavy ions facility

Abstract A heavy ion facility is now available at Laboratorio Nazionale del Sud (LNS) of Catania. It can deliver beams with an energy up to 100 MeV/amu. The facility is based on a 15MV HVEC tandem and a K = 800 superconducting cyclotron as booster. During the last year, the facility came into operation. A 58Ni beam delivered by the tandem has been radially injected in the SC and then has been accelerated and extracted at 30 MeV/amu. In this paper the status of the facility together with the experience gained during the commissioning will be extensively reported.

Scintillation hodoscopes for time-of-flight measurements

Abstract The performances of the TOF scintillation counters used in the SIGMA-AIAKS spectrometer are presented. The counters, made of NE110, are 150, 65 and 10 cm long, 10 cm wide and 1.5 cm thick. The time resolutions for minimum ionizing particles have been measured to be σ t = 0.18 ns, 0.14 ns and 0.11 ns respectively. The main contribution to the resolution is given by the photoe collection statistics determined by the decay time of the scintillator and the difference of the optical paths in the counter. The scintillation counters, assembled into hodoscopes of 1.5 × 3.2 m 2 and 0.65 × 0.8 m 2 are used for identification of particles through the TOF. The algorithms of off-line data processing are also presented.