The Accelerator Facilities at the Paul Scherrer Institute PSI E-Book

Werner Joho

• Herausgeber: Books on Demand
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 25

Veröffentlichungsjahr: 2019

Beschreibung

The Paul Scherrer Institute in Villigen Switzerland is the largest Research Institute in Switzerland. It has four worldclass accelerators: two Proton Cyclotrons and two Electron Accelerators. They produce beams of neutrons, pions, muons and X-rays. These are used in Materials Sciences, Energy Research and Medical Applications. A special cyclotron is dedicated to irradiate tumours with protons. Over the last 22 years more than 8'000 cancer patients have been treated this way.

Leseprobe

Introduction

The Paul Scherrer Institute PSI has four particle accelerators, which are described in this booklet.

1. Proton Ring Cyclotron 590 MeV

The project for a powerful proton accelerator started at ETHZ, the Swiss Federal Institute of Technology in Zurich, under professor J.P.Blaser in 1962. From the physicist Paul Scherrer he took over a small project group and redirected them towards the plan for a so-called meson factory. Hans Willax, the leader of this project, came up with a brilliant idea: he split up the conventional magnet of a cyclotron into separate sector magnets, making room in between them for powerful RF cavities. The first protons from this novel ring cyclotron were extracted in January 1974. The design goal of a current of 100 μA was reached in 1976. From the beginning it was realized that the current limit of the ring cyclotron was much higher than the one from the 72 MeV injector cyclotron from the Philips company. Thus a new Injector II cyclotron was conceived, and started operation in 1984. To increase the beam current to new and unexplored limits, the RF cavities of the ring cyclotron were replaced with more powerful ones. In 2009 a record value of 2.4 mA beam current could be reached, a value 24 times higher than the already ambitious design goal. At 590 MeV the average beam power is thus 1.4 MW, a world record to this day. The high energy protons produce spallation neutrons for materials science as well as pions and muons in record quantities.

2. Compact superconducting Proton Cyclotron, 250 MeV, used for irradiation of tumours

Starting in 1984, protons from the original 72 MeV cyclotron were used to irradiate eye tumours. But to eliminate deep-seated tumours one needs higher energy protons. Starting in 1996 a very small fraction of the 590 MeV proton beam was first degraded to energies between 100 and 250 MeV and then directed towards Gantry 1. With the so-called 3-dimensional spot scanning technique, invented by the physicist Eros Pedroni, tumours with complicated shapes can be irradiated. With steering magnets the proton beam can be deflected in the horizontal and vertical direction. In the third dimension - the direction of the beam - the range of the stopped beam can be changed by scanning the proton energy.