Development of carbide materials for radioactive ion beam production at high-power ISOL facilities

Short-lived rare isotopes are a challenge to produce in large quantities. Samples cannot be produced through off-line chemical separation: given their short half-life, they would decay away during the time it takes to extract them.  The production and study of new isotopes in the laboratory, at Radioactive Isotope Beams (RIB) facilities, provides a wide variety of information, from fundamental-research studies to the development of isotopes for cancer treatments and applications.

In the Isotope Separation On-Line (ISOL) method, the rare isotopes are being produced during the interaction of a light particle with a thick high-Z target. The process is summarized as follows: Protons from a high-energy driver impinge on an ISOL-target material in an enclosed container that is directly connected to an ion source. Nuclear reactions take place in the target with the production of a large variety of isotopes that come to rest embedded in the target material. Operating the target at high-temperature, these isotopes diffuse through the target lattice (move between the atoms of the material) to the surface where they are evaporated and then effuse from the target container to the ion source where they can be ionized. Afterwards, the ions are extracted by a potential difference of several tens of kV in a radioactive ion beam, which undergoes mass purification through an isotope mass separator.

Worldwide, there are several ISOL facilities under upgrade or being proposed, among which the ISOL@MYRRHA project at SCK•CEN. However, the success of these facilities is highly dependent on the capacity to solve issues related to target materials, which have to be capable to withstand reliably high power deposition by the intense high-energy proton beam over long periods of irradiation time without compromising diffusion efficiency of the created rare isotopes.

 

Objective

The objective of this PhD is to develop a high-porosity material fulfilling the challenging requirements of a high-power ISOL target used for the production of radioisotopes. The work will focus on:

 

  • Development and processing of carbide target material (such as TaCx) characterized by high porosity. (Work to be conducted at KU Leuven)
  • Detailed characterization of the produced material. A systematic study of the effect of the fast release according to various target-material properties (e.g. sintering, thermal diffusivity, porosity) will be realized. In ceramic materials the grains have the tendency to agglutinate, consequently forming larger grain, which reduces the diffusion efficiency of short-lived isotopes. A better understanding of this effect is crucial if one wants to operate ceramic target materials for long period (four weeks of longer) under high temperature (up to 2000 deg C). Open and closed porosity can play an important role in the isotope-release efficiency of the target material. (Work to be conducted at SCK•CEN)
  • Target optimization through a numerical study of high-energy-protons interactions with the target material (by use of FLUKA Monte Carlo simulations) and modelling the release of a typical product species (by combining an analytical computation and simulations with the Monte Carlo code MolFlow). (Work to be conducted at SCK•CEN)
  • Test of the proposed material under p-beam irradiation at an ISOL facility (application for beam-time at ISOLDE-CERN or/and ISAC-TRIUMF is considered).

Details on this PhD position

The research will be conducted in the Physics and Technology Innovation unit at SCK•CEN in Mol. Dr. Lucia Popescu (lpopescu@sckcen.be) will be the SCK•CEN mentor, Dr. Konstantza Lambrinou (klambrin@sckcen.be) will be the SCK•CEN co-mentor of the Ph.D work, whereas Prof. dr. ir. Jef Vleugels (Jozef.vleugels@mtm.kuleuven.be) from the Department of Materials Engineering of KU Leuven will be the University promotor. 

The candidate will obtain a Ph.D. in Engineering: Materials Engineering at the Faculty of Engineering of KU Leuven.

The candidate will have to pass the selection campaign of the Scientific Council of SCK•CEN, by an oral defence of the research theme on May 19-20 2016. The full procedure is explained at: http://academy.sckcen.be/en/Your_thesis_internship/PhD_thesis 

Application deadline: March 25, 2016 
Round 1: Result of the selection on file: April 26, 2016
Round 2: Oral presentations: May 19-20, 2016
Notification final result: June 15, 2016

For more information please contact:
Dr. Lucia Popescu (lpopescu@sckcen.be) SCK•CEN mentor 
Dr. Konstantza Lambrinou (klambrin@sckcen.be) SCK•CEN co-mentor 
Prof. dr. ir. Jef Vleugels (jozef.vleugels@mtm.kuleuven.be) University Promoter