[en] The injection system, for the Frascati Φ-factory DAΦNE, is designed to store ∼10¹³ positrons and electrons in the two main rings in an overall injection time at startup of ∼10 minutes. The system will consist of a high current electron Linac (E ∼ 250 MeV), a low current high energy electron-positron section (E > 510 MeV) and a compact damping ring in order, to avoid injection saturation, to increase longitudinal acceptance and to decouple the design of the main rings from injection requirements. The two Linac sections will provide ∼ 0.3 nC of positrons within ± 1% energy spread in 10 ns pulses for injection at 50 Hz into a single 76 MHz bucket of the damping ring. Extraction of the high quality damped bunch from the accumulator will take place at 1 Hz, filling one main ring bucket at a time. The Linac design foresees 3 m long 2π/3 TW constant gradient accelerating sections with SLED systems in order to increase the energy gain. The magnetic structure of the damping ring is designed to be accommodated in a 12 x 12 m² hall, and it is made of four quasi-achromatic bending sections and four long straights to accommodate injection and extraction pulsed elements and the RF system

[en] DAΦNE, the Frascati Φ-Factory presently under commissioning, is an e⁺/e^- collider whose injection system is composed by a = 60 m Linac and by a = 33 m long damping ring connected to each other and to the DAΦNE main rings by = 180 m of transfer line. Both the positron and the electron beams are alternately produced and accelerated by the Linac up to the operation energy of 510 MeV. Because of the high peak and integrated luminosity requested to DAΦNE, the requirements concerning some of the relevant Linac features, in particular the value of the positron macro bunch peak current are very demanding. During the Linac operation all the design values have been achieved and in most cases surpassed. A description of the relevant operational performances of the DAΦNE Linac is presented

[en] The injector of the LNF project LISA (LInear Superconducting Accelerator) is a room temperature system, consisting of a transport line for the beam at 100 KeV, of a capture section (a graded-β 2.5 GHz structure) which accelerates the beam to 1 MeV, and of an isochronous and achromatic transport line which injects the beam into the SC-Linac after a π-bending. The 100 keV beam delivered by the gun is composed of 1ms long macropulses. It is then chopped by a system of double choppers (50 and 500 MHz) which selects about 1% of the total beam, and bunched by a 500 MHz prebuncher which squeezes the bunch length to about 2 mm in order to obtain the peak current required by the FEL. 7 refs., 7 figs., 5 tabs

[en] The injector of the LNF project LISA (LInear Superconducting Accelerator) is a room temperature system, consisting of a 100 keV gun, a transport line with chopper and prebuncher systems, a capture section (a graded-β 2.5 GHz structure) which accelerates the beam to 1.1 MeV, and an isochronous and achromatic transport line which injects the beam into the SC-Linac after a π-bending. The status of the project is presented

[en] Physical verification by NDA in nuclear safeguards implies typically the adoption of an inverse-problem approach. This is, indeed, the definition of a problem, in which we use physical observables to deduct other physical quantities, which in our case are contained in the operator’s declaration. A typical example is the Plutonium mass, measured using Pu isotopics and neutron coincidence doubles counts, linked to the Pu 240 effective mass by a calibration. An alternative approach has been recently proposed and is now close to the in-field deployment by the Euratom Safeguards Directorate of European Commission’s DG ENER. In fact, the detailed knowledge of the physical processes that are taking place in the sample and within the detector allows computing the amount of the measured observable, by modelling the physical system as it results from the operator’s declaration, in a forward-problem approach. The present paper describes the first two examples of the forward-problem approach’s application to actual real-life safeguards verification. The first example deals with a Monte- Carlo-based modelling tool that has been developed to enable the inspectors to perform an improved verification of fresh fuel assemblies by neutron coincidence collar (NCC), taking into account the growing complexity of the fuel’s design. The second example shows how the verification of spent fuel is improved regarding the false alarm rate and the partial defect detection capability, by the integration of the automated review package iRAP and the modelling by the Oak Ridge transmutation code (ORIGEN). The potential applications of the new approach are not limited to the two described in this article, which, however, represent relevant proofs of concept of the potential that a change of perspective in verification by NDA may generate.

[en] The installation of the 25 MeV superconducting electron linac LISA is in progress at Frascati INFN National Laboratory. The installation is scheduled to be completed in Summer 1991 and commissioning will follow immediately. The status of the project is reviewed and the results of the first tests on various components are presented

[en] The electron-positron accelerator for the DAFNE project has been built and is in test at Titan Beta in Dublin, CA. This S-Band RF linac system utilizes four 45 MW sledded klystrons and 16-3 m accelerating structures to achieve the required performance. It delivers a 4 ampere electron beam to the positron converter and accelerates the resulting positrons to 550 MeV. The converter design uses a 4.3T pulsed tapered flux compressor along with a pseudo-adiabatic tapered field to a 5 KG solenoid over the first two positron accelerating sections. Quadrupole focusing is used after 100 MeV. The system performance is given in Table 1. This paper briefly describes the design and development of the various subassemblies in this system and gives the initial factory test data.

[en] The large number of elastic and inelastic collisions which take place during supersonic gaseous expansions produce not only acceleration and internal cooling of molecules, but also their alignment or orientation. The collisional alignment of the rotational angular momentum, corresponding to the orientation of the benzene molecular plane, in supersonic seeded expansions with lighter carrier gases is demonstrated via two complementary experiments: one interrogating benzene via polarized laser light IR absorption the other one probing its orientation via molecular beam scattering on rare gas targets. Typical seeding gases are helium, neon and their mixtures, and molecular hydrogen. Total stagnation pressures are of the order of ∼1 bar and ∼0.1 mm nozzle. A propensity is demonstrated for benzene molecules in seeded molecular beams to fly with the molecular plane preferentially oriented parallel to the molecular beam propagation direction. The analysis of the experimental results has been carried out using a phenomenological model which provides the fraction of molecules traveling in such a 'frisbee' mode. A frisbee propensity function is defined and found to range between 0.71 and 0.85, corresponding to IR and to scattering experiments, respectively. These values are significantly higher than the value 2/3, expected for a random distribution of molecular plane orientations. The trend in the measured values is discussed in terms of different angular cones of the supersonic expansion sampled in the two experiments and evidence is provided that the orientation is higher the narrower is the sampled cone aperture

[en] A research and development program in the field of RF superconductivity is in progress in Frascati, at the INFN Frascati National Laboratory, as part of a larger effort promoted by INFN in the field of superconductivity applied to accelerators, ranging from magnets to RF cavities and including basic research on the properties of superconducting (SC) materials. The program is carried out in collaboration with other INFN laboratories (mainly Milan and Genova) and with University groups. Its aim is to establish the feasibility of high energy, high duty cycle, high peak current superconducting electron linear accelerators. As a first stage of the program, the construction of a small 49 MeV SC linac called LISA has been authorized and is under way. The authors first present the status of LISA and then give a summary of the other R ampersand D activities in progress or planned. 13 refs., 5 figs., 5 tabs

[en] The construction of a 25 MeV superconducting (SC) radio-frequency (RF) electron linac is in progress at Frascati INFN Laboratories. It will be a test machine for advanced technology oriented towards future linear colliders. In a first phase of the project the machine will be applied to realize an infrared FEL. In a second phase, in addition to the acquisition of general techniques related to SC RF acceleration, LISA will constitute the injector of a larger SC linac (ARES project). A description and a status of LISA and a few words of future developments follow