The fragmentation of carbon monoxide dimers induced by collisions with low energy Ar ions is investigated using the COLTRIMS technique. The presence of a neighbor molecule in the dimer serves here as a diagnostic tool to probe the lifetimes of the CO molecular dications resulting from the collision. The existence of metastable states with lifetimes ranging from 2 ps to 200 ns is clearly evidenced experimentally through a sequential 3-body fragmentation of the dimer, whereas fast dissociation channels are observed in a so-called concerted 3-body fragmentation process. The fast fragmentation process leads to a kinetic energy release distribution also observed in collisions with monomer CO targets. This is found in contradiction with the conclusions of a former study attributing this fast process to the perturbation induced by the neighbor molecular ion.

We report on experimental results obtained from collisions of slow highly charged Ar9+ ions with a carbon monoxide dimer (CO)(2) target. A cold target recoil ion momentum spectroscopy setup and a Coulomb explosion imaging approach are used to reconstruct the structure of the CO dimers. The three-dimensional structure is deduced from the two-body and three-body dissociation channels from which both the intermolecular bond length and the relative orientation of the two molecules are determined. For the three-body channels, the experimental data are interpreted with the help of a classical model in which the trajectories of the three emitted fragments are numerically integrated. We measured the equilibrium intermolecular distance to be R-e = 4.2 angstrom. The orientation of both CO molecules with respect to the dimer axis is found to be quasi-isotropic due to the large vibrational temperature of the gas jet.

The deep trapping gate device concept for charged particle detection was recently introduced in Saclay/IRFU. It is based on an n-MOS structure in which a buried gate, located below the n-channel, collects carriers which are generated by ionizing particles. They deposit their energy in a volume which extends in the bulk, below the buried gate. The n-channel device is based on holes in-buried gate localization. Source–drain current modulation occurs, measurable during readout. The buried gate (Deep Trapping Gate or DTG) contains deep level centers which can be introduced during process or may be made with a Quantum Well. The device can be scaled down providing a micron range resolution. The proof of principle for such a device was verified using 2D device and process simulations. Work under way focusses on the study of building blocks. In this contribution, the pixel proof of design, using existing fabrication techniques will be discussed first. The use of this pixel for photon imaging will be discussed.

In high energy physics point to point resolution is a key prerequisite for particle detector pixel arrays. Current and future experiments require the development of inner-detectors able to resolve the tracks of particles down to the micron range. Present-day technologies, although not fully implemented in actual detectors can reach a 5 micometer limit, based on statistical measurements, with a pixel-pitch in the 10 micrometer range. Attempts to design small pixels based on SOI (Silicon On Insulator) technology will be briefly recalled here. This paper is devoted to the evaluation of the building blocks with regard to their use in pixel arrays for the accurate tracking of the charged particles. We will make here a simulations based quantitative evaluation of the physical limits in the pixel size. A design based on CMOS (Complementary Metal-Oxide-Semiconductor) compatible technologies that allows a reduction of the pixel size down to the sub-micronmeter range is introduced. Its physical principle relies on a buried carrier-localizing collecting gate. The fabrication process needed by this pixel design can be based on existing process steps used in silicon microelectronics. The pixel characteristics will be discussed as well as the design of pixel arrays. The existing bottlenecks and how to overcome them will be discussed in the light of recent ion implantation and material characterization.