V. Stagno

A small electrostatic accelerator for a powerful continuous-wave free electron laser

Abstract An electrostatic accelerator for a free electron laser (FEL) source which can operate in the millimeter-centimeter region is presented. The most convenient scheme for 10 A - 2 MeV is studied. A conceptual design of a powerful continuous-wave FEL coupled with that machine is discussed.

A storage ring for crystalline beam studies

Abstract The possibility of generating crystallized ion beams, i.e. beams whose particles are located at fixed positions, has always excited the interest of most people working on particle accelerators. The reason of this interest has many aspects: knowledge either of a completely new research field or of some of the applicative potentialities, connected with crystalline beams, would justify a careful investigation of this subject. After the successful exploitation of electron cooling in several heavy ion storage rings the possibility of generating crystalline ion beams became more realistic. New cooling methods, like laser cooling, give a further opportunity to reach an ultracold system of particles necessary for the state transition to the crystalline configuration. The conceptual design of a low-energy heavy-ion storage ring, called CRYSTAL, proposed for the experimental demonstration of crystalline beams at Legnaro Laboratories is presented. The physics of crystalline beams as well as the main criteria to design a storage ring suitable to crystallize ion beams are discussed. The effects of instabilities for space charge dominated beams, shear forces in dipole magnets and lattice periodicity breaking are also discussed in detail.

Prototype of a tubeless vacuum insulated accelerator

Abstract The construction of a small prototype of a new kind of Cockroft-Walton accelerator is in progress. The onion-wise disposal of the capacitor plates allows a high-gradient compact machine, as well as the assurance of reliability. This kind of machine can overcome the problem of having an accelerating column of high perveance. In fact, because of its peculiar electromechanical structure, the whole high voltage generator can be settled inside a vacuum chamber and then an electron beam can be accelerated directly by the capacitor plates of the voltage multipliers. The scaled-up version of this machine seems to be particularly suited for high-current, high-efficiency applications, like FEL, ion acceleration for plasma heating or containment. The status report of the experiment will be presented.

Physics and simulations of a new design multistage collector inserted in an immersed-flow configuration electrostatic accelerator

Abstract Physics and simulations of a new multistage collector for the recovery of a warm electron beam are extensively discussed. The problem of the transition region between the decelerating column and the collector in an immersed flow configuration is also presented. The charge recovery of this new collector seems to be good.

A transition radiation detector for particle astrophysics experiments using low power consumption electronics

Abstract We have designed a transition radiation detector (TRD) of about 75 × 80 cm 2 active surface to discriminate positrons from protons in an experiment to be performed on balloon flights to search for primordial antimatter. The TRD is made of ten modules consisting of a carbon fiber radiator followed by a multiwire proportional chamber (MWPC). In order to achieve a proton-electron rejection factor of the order of 10 −3 with a strict limitation on power consumption to 35 mW per MWPC channel, as required by experimental constraints, we have developed and tested a prototype based on low power consumption “cluster counting” electronics. Comparisons of the performances of this prototype are made with those of a previous similar detector equipped with standard fast electronics and an analogous TRD from other authors.

SEAFEL experiment: Anlysis and design

Abstract Problems relevant to a continuous-wave FEL operating in the cm-mm region are investigated. The SEAFEL (small electrostatic accelerator for free electron laser) experiment, in progress at LNL (Laboratori Nazionali Legnaro), is presented. The electrostatic accelerator is of the Cockroft-Walton type and delivers a 3 A, 0.7 MeV electron beam. This current level can be reached with a beam recovery system. The “immersed-flow” configuration for the beam transport is adopted. The FEL has a 1.5 m long permanent-magnet helical undulator and a resonator with Bragg mirrors.

Simulation of a laser diagnostics to detect the string configuration of an ion beam in a storage ring

Abstract Simulation of a laser diagnostics for detection of ordered structures in an ion beam is shown with reference to presently operating or under design storage rings in which laser cooling is implemented. The diagnostics, however, could potentially be extended to any storage ring. The method is capable to firmly resolve ordering of an ion string with currently available technology in a non-destructive way. Information concerning short-range correlation can be also inferred for very cold but not crystalline ion beams – a condition that is more likely to be reached in presently operating storage rings.

CRYSTAL: a storage ring for crystalline beams and other applications

Abstract The possibility of generating crystallized ion beams has always excited the interest of most people working on particle accelerators. The reason of this interest has manifold aspects: either a knowledge on a completely new research field or some of the applicative potentialities, connected with crystalline beams, would justify a careful investigation on this content. The Conceptual Design of a low-energy heavy-ion storage ring, called CRYSTAL, proposed for the experimental demonstration of crystalline beams at Legnaro Laboratories is presented. Besides the study of crystalline beams the CRYSTAL Storage Ring (CSR) offers a large potential for fundamental research in nuclear, atomic and molecular physics. In this sense, the development of a second generation cooler ring with better lattice will give large possibilities to investigate more deeply in fundamental Physics.

Ion beam crystallization

After the successful exploitation of electron cooling in several heavy ion storage rings the possibility of generating crystalline ion beams gained the interest of particle accelerator physicists. New cooling methods, such as laser cooling, give further opportunity to reach ultra cold system of particles necessary for the state transition to the crystalline configuration. Crystalline beams will give insight into a completely new research field, reaching higher standards in precision measurements and techniques. The applicative potentialities of crystalline beams justify a careful investigation on this subject.The conceptual design of a low-energy heavy-ion storage ring, called CRYSTAL, proposed for the experimental demonstration of crystalline beams at Legnaro LNL is presented.