ANAlysis and Ion beams for Radiobiology and the Environment

IP2I technology platform

Ionizing radiation is the object of a certain amount of media coverage, probably linked to a real ambivalence: fascinating by its potential, worrying by the risk it can represent for the environment and health.

ANAFIRE Lyon is a center of expertise on ionizing radiation, high-level, independent expertise, associated with measurement tools and accredited analyses. This expertise is anchored in national and international collaborations.

The challenge of the platform is to make a significant contribution to research related to the use of ionizing radiation and the characterization of its effects, while offering locally a quality metrology open to economic and social partners.
The platform is structured in 6 portals which are different access points for the pooling of equipment.

The Van de Graaf 4 MV

The Van de Graaf is an electrostatic accelerator raised to a potential of 3.5 MV allowing it to accelerate mono- or double-charged ions up to 7 MeV. This machine has a double particularity: the accelerator tube is installed vertically and the beam lines are horizontal. The passage of the tube to these lines is done thanks to a deflection magnet mounted on a rotating head: switching from one beam line to another is then very fast and easy since all you have to do is to turn the magnet.

The Penning source

This accelerator is composed of a Penning source which allows to produce ions from gases (H, 3He, 4He, D). The ions can be mono- or double-charged.

The gas pedal tube

This tube allows the ions to be accelerated by a voltage of up to 3.5 MV, which corresponds to an energy of 3.5 MeV for monocharged ions and 7 MeV for doubly charged ions. This tube is composed of a succession of resistors allowing a progressive voltage drop. The risks of electrical breakdown being high, the source and the acceleartor tube are placed inside a tank filled with an insulating gas (N + CO2 at 20 bars).

The deflection magnet

It is a 90° magnet that separates isotopes of the same variety of ions and removes impurities from the selected beam. Depending on the mass of the desired isotope, the corresponding magnetic field is applied; only ions with the right mass are deflected, the others being lost in the gap of the magnet.

This magnet is mounted on a rotating head allowing easy change of beam lines.

The different beam lines

The beam is then focused by electrostatic quadrupoles and magnetic coils. Once the beam is focused it is then sent to the beam lines.

There are several channels available depending on the purpose of the beam:

• Ion beam analysis (RBS, NRA, PIXED, …)
• Irradiation of materials
• Biological irradiation (Radiograaff)

400 kV implanter (IMIO400)

The principle of ion implantation is to accelerate positive ions in an electric field to give them an energy that allows them to penetrate a given depth in a substrate. The advantages of ion implantation are precision in isotope selection, fluence control and implantation depth, and reproducibility of these parameters.

IMIO400 was entirely designed and realized by the collaboration of the IP2I’s design office, mechanical department and ion beam department in the 90s. It has been regularly renovated and upgraded.

IMIO400 Technical Specifications

• Beam energy: 60 to 800 keV
• Types of ions implanted: almost all the elements of the periodic classification (gaseous, liquid or solid species). Isotopic selection thanks to an electromagnetic analysis magnet.
• Currents produced: from a few µA to a hundred µA
• Minimum beam size: 2 mm
• Electrostatic scanning: from 2.6 x 3.1 to 4.6 x 10.6 cm2.
• Maximum implantation depth: 500 nm.
• Implanted doses: from 1012 at.cm2 to 1017 at.cm2.
• Implantation temperature :
  • Ambient temperature with cooling of the microscope slide by water circulation.
  • Possibility to use a heated sample holder up to 600°C.

  IMIO 400 platform

  The ion source

  The Bernas-Nier type source allows the ionization of gaseous, solid or liquid species. Almost all elements of the periodic table can be ionized. The source has an inlet furnace for solid elements. In addition to the heating they undergo a chemical attack by a chloride, typically CCl4, and are thus vaporized before being introduced into the source. Thus, whatever the natural physical state of the starting products, the chemical elements to be implanted are introduced in the vapor state into the plasma in the source. The atoms or molecules are then ionized by electronic impact in the discharge maintained between the anode and the hot cathode which emits electrons by thermoelectronic effect. This technique makes it possible to ionize, once or twice, almost all the elements of the periodic classification.

  

  Inside the IMIO source – © IP2I

  The electromagnetic magnet of analysis

  After a pre-acceleration of 30 kV, the isotopes are sorted by an electromagnetic analysis magnet. This magnet allows mass sorting of all the ions from the source, and in particular to make an isotopic selection.

  The acceleration

  At the exit of the magnet the sorted ion beam is accelerated in an electric field with a voltage of up to 400 kV. The choice of the voltage will thus determine the energy of the beam.

  The implantation

  During the set up and in particular during the power-up, the gas pedal platform is controlled from a console isolated from the machine. It is also from this console that the beam produced will be focused until it has a diameter of about 2 mm.

  The implanted surface is then adjusted thanks to a horizontal and vertical scanning generator.

  Some examples of implantations performed on IMIO400

  • 37 Cl+ in graphite
  • 133Cs++ in carbon compounds.
  • 129 Xe++ in various ceramics.
  • 18O+ in SiC
  • 15N+ in SiC
  • 133 Xe+ in UO2.
  • 1H+ in SiC heated to 450°C.

  Samples can be heated during implantation.

  The tool is open to all and all requests are studied on a case-by-case basis before acceptance and quotation.