Beam diagnostics at DAFNE with fast uncooled IR detectors

TL;DR

This paper discusses the development and testing of fast uncooled IR detectors for bunch-by-bunch diagnostics at DAFNE, enabling improved monitoring of electron bunches and bunch instabilities.

Contribution

It introduces the use of mid-IR uncooled photoconductive HgCdTe detectors for high-resolution bunch diagnostics at DAFNE.

Findings

Recorded 2.7 ns long electron bunches with 600 ps pulse width.

Set up an IR radiation collection and detection system at DAFNE.

Progress in testing photovoltaic detectors with sub-ns response times.

Abstract

Bunch-by-bunch longitudinal diagnostics is a key issue of modern accelerators. To face up this challenging demand, tests of mid-IR compact uncooled photoconductive HgCdTe detectors have been recently performed at DAFNE. Different devices were used to monitor the emission of e- bunches. The first experiments allowed recording of 2.7 ns long e- bunches with a FWHM of a single pulse of about 600 ps. These results address the possibility to improve diagnostics at DAFNE and to this purpose an exit port on a bending magnet of the positron ring has been set-up. An HV chamber, hosting a gold-coated plane mirror that collects and deflects the radiation through a ZnSe window, is the front-end of this port. After the window, a simple optical layout in air allows focusing IR radiation on different detectors. The instrumentation will allow comparison in the sub-ns time domain between the two rings and to identify and characterize bunch instabilities. Moreover, to improve performances tests of new photovoltaic detectors with sub-ns response times are in progress. We will briefly summarize the actual status of the 3+L experiment and will discuss future applications of fast IR photovoltaic detectors and the development of fast IR array detectors.