Status report of the 20 UD TANDAR accelerator in Buenos Aires

A. ARAZI; J.C. DONAIRE; A. FERNÁNDEZ SALARES; G. GODOY, ; N. LEMA; G.V. MARTÍ; C. MÍGUEZ; S. MILANESE; G. MOLINARO; F. ORLANDO; C. PALACIOS; O. PROFESSI; J. RUFFINO

Albuquerque

Simposio; Symposium of North Eastern Accelerator Personnel,; 2015

Sandia National Laboratories

The 20 UD tandem accelerator at Buenos Aires was built by NEC on mid 80s and it was originally devoted to basic studies on nuclear structure and reaction mechanisms, operating at terminal voltages up to 17 MV. While many of these research lines are pursued nowadays, an increasing amount of applications have been performed: research on radiation damage on electronic devices and solar cells, PIXE and RBS analysis, microbeam machining and AMS. Main improvements on the accelerator were the introduction of a 40-Samples SNICS-II ion source on 2000 and the replacement of corona points by resistors on 2005. More recently (2013), a new SNICS-II ion source was installed and is currently operating. Due to its high cost, lost SF6 has been from 2005 up to now continuously compensated by addition of N2. Mainly because of this reason, the terminal voltage is nowadays limited to 10 or 12 MV, depending on the gas pressure. We have had many problems with the charging systems, mainly related with broken nylon links of the charging chains which were finally solved as we will explain in this talk. This, in contrast with other facilities, turned to be not related with BDP chemical attack but with mechanical reasons. The correct sliding of the pulley?s counterweight at the high-voltage terminal and the improvements made on the oiling system for the chains allowed us to have now chains running more than 5000 hours without further problems. Future planned improvements are: a new PLC-based control system, fixing leakages at the SF6 gas system and the injection of additional SF6, alignment of the accelerator tubes to improve beam transmission and the installation of a recently bought gas stripper (with recirculation) and a Wien filter. The later will be used in a time-of-flight dedicated beam line for AMS measurements. In our presentation we shall give an overview of the problems encountered andimprovements made over the last years.