F. Cevenini

Preliminary results on dielectric mirror damage due to the radiation of a high K undulator

Abstract Due to the high K value (4.8) of the LELA undulator, we expect a significant UV induced damage of TiO2SiO2 dielectric mirrors. Preliminary tests on commercial grade mirrors exhibit a great loss of reflectivity, due to two distinct processes of induced degradation. One of them is surface absorption of carbon in the upper SiO2-air interface. It is not affected by annealing. The other corresponds to a volume damage induced by the high energy radiation present during injection into the accelerator or during the runs at 1.5 GeV for synchrotron radiation production.

Commissioning and performance of a low emittance, long pulse electron gun for the superconducting linac LISA

Abstract A 25 MeV superconducting linear accelerator (LISA) is under construction in the Frascati INFN Laboratories. Here we describe the design and measured pe

Final report on the LELA experiment

Abstract Progress in the LELA (free electron laser on ADONE) experiment from September 1986 to July 1987 is described. Improvements in machine lattice and control, and automation in cavity alignment allowed for a maximum Q factor of ≈ 103.

Optical cavity alignment and mirror damage in the LELA FEL experiment

Abstract The alignment of the LELA optical cavity, 17.5 m long, is described. The procedure to attain a close alignment of the undulator radiation axis and the cavity axis using an external laser is reported. Measurements of Q from stored light spectra are presented. Mirror degradation at increasing integrated electron currents is considered.

Progress report on the LELA experiment

Abstract After the installation of the optical cavity of the LELA experiment, a series of tests of the cavity alignment relative to the electron beam direction has been performed, showing the problems due to the peculiarity of this cavity. The use of piezoelectric translators in ultrahigh vacuum has permitted a smooth and precise control of the cavity optical axis. Preliminary results on mirror damage due to UV radiation have also been obtained.

Inverse free electron laser on a storage ring

Abstract The acceleration and the energy spread induced by a sequence of laser pulses hitting an electron bunch circulating through a storage ring are analyzed. The statistics of the energy-phase of the bunch is analyzed through a formalism based on a set of “storage ring eigenfunctions”.

A remote control system for the LELA experiment

Abstract A modular system for closed loop computer control of stepping motors has been realized and used for optical component movement of LELA experiment in the radiation risk area. A CAMAC module, controlling up to 15 stepping motors, a NIM dual motor driver and a special purpose circuit for computer interfacing are described.

A prom simulator and word generator for microprogrammable high speed processor development

Abstract A high speed Word Generator and PROM Simulator for hardware and software development of ECL 4 bits microprocessors systems has been constructed. The instrument has a 256×48 bits RAM and can be used s in-circuit PROM emulator at a maximum working frequency of 25 MHz and as word generator on external trigger at a full 50 MHz frequency. Both manual and computer controlled programming are available.