P. Patteri

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.

Analysis of optical transition radiation emitted by a 1 MeV electron beam and its possible use as diagnostic tool

Abstract The main features of optical transition radiation (OTR) backward emitted by a 1 MeV electron beam crossing a vacuum-to-metal boundary are presented. The possible use of OTR as a diagnostic tool for such a low energy beam is discussed, and some preliminary experimental data are presented.

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

On line calorimetric measurement of the quality factor of superconducting accelerator cavities

Abstract A comparative precise method to measure the Q factor of installed superconducting cavities is described. Data taken on the cavities of the 25 MeV s

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.

Optical cavity of the Adone FEL experiment

Abstract A detailed description of the parameter choice for the LELA optical cavity is presented. Particular attention has been devoted to the alignement problems solved by means of a remote control system. First results on mirror damage due to UV radiation will be also reported.

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.

Commissioning and operating experience with the LISA superconducting accelerator

Abstract The commissioning of the LISA superconducting (SC) RF electron linac at INFN Frascati Laboratories has been concluded although, due to a change in program priorities, the full possibilities of the machine have not been exploited. In this report we illustrate the results achieved so far and the difficulties encountered in commissioning, with the hope that this material might be of some help to those who intend to start the enterprise of building a SC linac in a non-specialized environment. The part concerning the SC system is particularly stressed, but a relevant attention is also devoted to the traditional room temperature injector, the proper setting of which is fundamental to achieving the high beam quality that such a machine allows.