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ultra-COLD gas for the production of a Bright Electron And Monochromatic ion Source

Final Report Summary - COLDBEAMS (ultra-COLD gas for the production of a Bright Electron And Monochromatic ion Source)

The objective of the COLDBEAMS (for ultra-COLD gas for the production of a Bright Electron And Monochromatic ion Source) project was to increase knowledge-sharing and mutual understanding between an SME, Orsay Physics (OP), France (since april 2014 part of TESCAN-ORSAY HOLDING), and two Academic partners, Laboratoire Aimé Cotton (LAC), France, and the Dipartimento di Fisica of the Università di Pisa (UNIPI), Italy.
The technical-scientific focus of this strategic partnership was on the development of a new electron and ion source based on ionized ultracold atoms. The use of this revolutionary incident source could create an important breakthrough in the Focused Ion Beams (FIB) or in energy electron source technology with substantial improvements in terms of monochromaticity, brightness and minimum spot size.
The joint research project exploited complementary expertise of the participants in a well-coordinated and synergic effort. Orsay Physics is one of the leading companies in realization and commercialization of FIB beam columns, dedicated to surface analysis systems. The OP team has provided to the partners the know-how on the ion/electron optics, and the related electronics, with a special emphasis on the engineering and industrialization aspects. LAC from the Centre National de la Recherche Scientifique (CNRS), is the co-ordinator of the project and, as the UNIPI team, is specialized in laser cooling of atoms. The LAC is also specialist in ultra-cold plasma physics whereas the UNIPI is specialized on applications of the laser manipulation techniques to materials science. The LAC and UNIPI teams have provided to OP the know-how on cold atom technology and developed in their own laboratories experiments aimed at assessing the potential of the approaches explored. A complementary strategy was deployed: the LAC team developed sources for ion and electron beams using advanced laser manipulation schemes, whereas UNIPI focused its scientific efforts on the on-demand delivery of ion bunches produced from a laser cooled atom beam.
The main result of the collaboration is the realization in the OP laboratory of a prototypal apparatus for focused ion beams based on the ionization of cold atoms. The apparatus has already demonstrated the capabilities of the technique for surface imaging and milling, with, at low energies, performances already better than a standard FIB showing a huge potential for further improvements able to push the performance well beyond the present state-of-the-art.
The achievement of such an ambitious result involved a tremendous development in terms of specific competence and experimental facilities. This was made possible thanks to the exchange of knowledge and of manpower enabled by the IAPP Coldbeam project. On the other hand, the OP company was stimulated to make important investments in terms of finance and resources, and presently sees the application of cold atom technologies as a perfectly viable and fascinating route for attacking in the mid-term the challenging market of FIBs with a revolutionary product.
Fostering the development of new electron and ion sources required the coordinated merging of two different competences at the cutting edge of sophisticated technologies: the one in the fabrication of focused electron or ion beams and the one in laser cooling and manipulation of neutral atoms. In this respect, the project addressed several domains, from nanofabrication to materials science, which employ thousands of researchers and represent a large and expanding market. Thus, any development of such new sources is susceptible to open new research areas or extend the limits of the present ones, also outside the boundaries of FIB technologies.
The main outcomes of the IAPP Coldbeams project related to its specific objectives include:
* The realization of a brilliant, transversally collimated Cs beam (flux > 10^12 at/s) has been attained. A new ion optic compatible with the cold Cs source has been realized. A complete apparatus has been put in operation at OP thanks to the large efforts in secondment deployed in the project. This complete system succesfully demonstrate the use of cold atoms for a FIB column, in imaging mode and milling mode where modification of surface is achieved. The first publishable preliminary results are presented in the joint publication appeared in Phys. Rev. A 88, 033424 (2013), “High-flux monochromatic ion and electron beams based on laser-cooled atoms”.
* An operational 2D cesium MOT has been realized and extensively investigated at LAC. Thanks to the use of the same configuration as the one installed at OP, and thanks to the possibility of seconding personnel from academic to industrial partners, a careful optimization of the system was carried out and a wealth of alternative strategies could be assessed in view of the practical application. They included the use of Rybderg states as precursors of the electrons, which holds the potential for substantial improvements of the beam monochromaticity. Moreover, the IAPP Colbeams project enabled starting a collaboration with other academic institutions such as ISMO, with the aim to perform Electron Controlled Chemical Lithography (ECCL) experiments, and University of Mainz for Photoemission electron microscopy (PEEM) studies. The success of this collaboration has been validated by an important (near 1 M€) ANR/DFG contract to realize an HREELM (High Resolution Electron Energy Loss Microscope).
* A bright laser cooled Cs beam from a Pyramidal-MOT has been realized at UNIPI and ions have been obtained through photoionization. A complete characterization of the system has been carried out, and the ability to produce ion bunches with a predefined amount of charge and controlled dynamical properties has been demonstrated. The main results will appear in joint publications presently in the submission stage. Within the project, the activity had the crucial role to identify advantages and pitfalls of an approach massively involving laser cooling technologies for the preparation of the primary source for ions.
* Knowledge exchange recognized at the international level was achieved by the project. This is a quite relevant result considering the novelty of the scientific and technical themes involved and the impact their development could have in a broad range of applications. The Coldbeams conference was organized in October 2012 in Nîmes, France, which had 60 participants from around the globe (more information can be found on the website of the project or one the web site of the conference
All the produced results, including those not immediately suited for industrial applications, confirm the possibility to use a laser cooled atom beam as the primary source for producing an ion or electron beam with exotic properties, able to address the crucial issues in the present beam technologies.