The existing and future accelerator facilities at GSI and FAIR offer unique opportunities for interdisciplinary research, especially for material science and nanotechnology. On their way through polymers, swift heavy ions with GeV energy deposit enormous energy densities along their trajectory, generating long nanoscopic damage trails known as ion tracks. Ion-track technology utilizes the small track size (few nm) combined with the extensive track length (up to 100 μ m and more) to synthesize and control the geometry of high-aspect-ratio nanostructures such as tailored nanochannels and nanowires. In particular, electrodeposition and ion-track nanotechnology provide an excellent platform for developing unique 3D networks of nanowires with controlled dimensions, composition and crystallographic properties. Here, a summary of recent results obtained on the synthesis and characterization of stable 3D architectures of semiconductor and semimetal nanowires, and their implementation in the fields of photoelectrochemistry and thermoelectrics, is presented.

The deposition of energy in large and small sensitive volumes is studied after ultrahigh energy heavy-ion irradiation. We demonstrate that the energy deposition increase effect previously reported in p-i-n diode detectors due to delta electrons occurs only in large sensitive volumes, but not in small ones, typical of advanced microelectronic devices, such as the cells of a 3-D NAND Flash memories. We attribute this effect to the trajectories of the secondary electrons.

The vertical line fault mechanism occurring in NAND flash devices under heavy-ion irradiation is described in detail. The location where the fault is generated as well as the recovery sequence are identified.

This paper discusses the use of nanomaterials for the improved performance of time-of-flight particle detectors based on secondary electron emission (SEE). The purpose of the research presented in this paper is to find a nanomaterial that has a higher SEE than gold. In this article, we present a measurement of the SEE properties from 1D (one-dimensional) nanostructures of ZnO and ZnO/GaN (ZnO with GaN coating) composed of a mostly regular pattern of nanotubes grown on a thin Si 3 N 4 substrate. The study was performed with 4.77 meV/u Au beam. We observed an average increase of 2.5 in the SEE properties from the 1D ZnO nanotubes compared to gold.

Heavy-ion microbeams are employed for probing the radiation-sensitive regions in commercial silicon carbide (SiC) vertical double-diffused power (VD)-MOSFETs with micrometer accuracy. By scanning the beam spot over the die, a spatial periodicity was observed in the leakage current degradation, reflecting the striped structure of the power MOSFET investigated. Two different mechanisms were observed for degradation. At low drain bias (gate and source grounded), only the gate-oxide (at the JFET or neck region) is contributing in the ion-induced leakage current. For exposures at drain-source bias voltages higher than a specific threshold, additional higher drain leakage current is observed in the p-n junction region. This provides useful insights into the understanding of basic phenomena of single-event effects in SiC power devices.

Parameters to Facilitate Correlation of Laser-and Heavy-Ion-Induced Single-Event Transients in SiGe HBTs."This paper presents an approach for determining the optimal set of laser parameters (i.e., pulse energy, focused spot size, wavelength, and pulse duration) for correlating single-event transients (SETs) induced via two-photon absorption (TPA) and heavy ions.Pulsed lasers can be used as a complementary tool to augment the results obtained through traditional heavy-ion test campaigns performed for space qualification of electronic components.Historically, one of the challenges in using pulsed lasers for SEE testing has been achieving quantitative correlation between laser-and ion-induced SEEs.Several studies have been successful in correlating singlephoton absorption and heavy-ion results.However, due to the increased complexities of charge generation using TPA, achieving such correlation has been challenging.The approach presented in this paper focuses on "feature matching," a terminology borrowed from machine learning concepts.When using this approach, certain waveform "features" are extracted from the measured heavy-ion-induced SETs (e.g., transient peak amplitude, collected charge, and transient duration).These features are then compared with those extracted from the SETs induced using a pulsed laser for a variety of optical parameters.An optimization routine can be used to find the optimum set of parameters that result in matched features between ion and laser data.This approach was applied to a silicon-germanium heterojunction bipolar transistor.An optimal spot size was identified for this particular device, and a one-to-one relationship between heavy-ion linear energy transfer and laser pulse energy was obtained.These results showed excellent waveform matching between laser and ion data when the optimized laser conditions were used.Due to the generality of the approach, which focuses on measured "features" of SETs, a similar procedure can be performed for a variety of semiconductor devices and technology platforms.This ion/laser calibration process can lead to the creation of a "library" containing the optimal laser parameters Digital Object Identifier 10.

We have realized the importance of developing micro/nanofabrication techniques for fluoropolymers in order to further pursue their potential for future applications. This paper is devoted to the following two topics, i.e., ion-track membranes and ion-track-grafted electrolyte membranes for fuel cell applications, both of which include the creation of fluoropolymer-based nanostructured membranes with swift heavy ions. Latent tracks of the MeV-GeV heavy ions in an organic polymer foil can sometimes be chemically etched out to form a membrane with micro- and nano-sized through-pores, the so-called ion-track membrane. Our focus is on ion-track membranes of poly(vinylidene fluoride) (PVDF), which have also been considered as a matrix of functionalized polymer membranes. Although the PVDF-based ion-track membranes have already been reported, their preparation methods have never been optimized. The etching behavior mainly depended on the energy deposition of the ion beams, and thus its depth distribution, estimated by a theoretical simulation, was successfully applied to control the shapes and diameters of the etched pores. The electrolyte membranes for fuel cell applications were prepared by the direct ion-track grafting method. The membrane preparation involves (i) irradiation of a fluoropolymer (mostly the poly(ethylene-co-tetrafluoroethylene)) base film to create reactive species, (ii) graft polymerization of styrene or its derivative monomer into latent tracks, and (iii) sulfonation of the graft polymers. Interestingly, the resulting membranes exhibited an anisotropic proton transport, i.e., higher conductivity in the thickness direction. Based on microscopic observations, this is probably because the nearly columnar electrolyte phase with a width of tens-to-hundreds of nanometers extended through the membrane. Other excellent membrane properties, e.g., a high dimensional stability, should also be due to such a controlled structure.

The Seebeck coefficient and electrical resistance of Bi1-xSbx nanowire arrays electrodeposited in etched ion-track membranes have been investigated as a function of wire diameter (40-750 nm) and composition (0 ≤ x ≤ 1). The experimental data reveal a non-monotonic dependence between thermopower and wire diameter for three different compositions. Thus, the thermopower values decrease with decreasing wire diameter, exhibiting a minimum around ∼60 nm. This non-monotonic dependence of the Seebeck coefficient is attributed to the interplay of surface and bulk states. On the one hand, the metallic properties of the surface states can contribute to decreasing the thermopower of the nanostructure with increasing surface-to-volume ratio. On the other hand, for wires thinner than ∼60 nm, the relative increase of the thermopower can be tentatively attributed to the presence of quantum-size effects on both surface and bulk states. These measurements contribute to a better understanding of the interplay between bulk and surface states in nanostructures, and indicate that the decrease of Seebeck coefficient with decreasing diameter caused by the presence of surfaces states can possibly be overcome for even thinner nanowires.

Motivation Repair of DNA damage in heterochromatic areas (HC) is a challenge for cells, but eukaryotic cells have developed mechanisms to enable efficient repair of heterochromatic DNA double strand breaks (HC-DSBs). These damages are moved to the euchromatic-heterochromatic border, and at the same time decondensation of the chromatin takes place. This process was first shown in Drosophila by Chiolo et al. [1] and in mammalian cells by our group [2] and might support further repair. In order to identify possible factors involved in these processes we analyzed DSB-relocation in wild-type and deficient /knock-down murine fibroblasts cells after targeted irradiation at the GSI microprobe.

Sputtering experiments with swift heavy ions in the electronic energy loss regime were performed by using the catcher technique in combination with elastic recoil detection analysis. The angular distribution of particles sputtered from the surface of LiF single crystals is composed of a jet-like peak superimposed on a broad isotropic distribution. By using incident ions of fixed energy but different charges states, the influence of the electronic energy loss on both components is probed. We find indications that isotropic sputtering originates from near-surface layers, whereas the jet component may be affected by contributions from depth up to about 150nm.

We report the upgrade of the epifluorescence microscope of the GSI heavy-ion microprobe with a galvo-scanned, 488 nm laser diode. The laser is focussed into the object plane by the water-immersion objective resulting in a focal spot size of about 1 μm. To increase temporal and spatial resolution a water-immersion objective with a high numerical aperture is integrated into the custom-build microscope. The upgraded system can now be used to bleach GFP-tagged proteins recruited to DNA damage induced by targeted single-ion irradiation. The system is demonstrated on NIH 3T3 cells with Ku80-GFP ion-targeted in heterochromatic and euchromatic DNA. Fluorescence recovery after photobleaching (FRAP) is shown to be significantly slower in heterochromatin.

Experimental data presented in our earlier paper [Toulemonde et al., Phys. Rev. B 85, 054112 (2012)] indicate that there are two thresholds for damage creation by swift heavy ions in CaF2. Moreover, the comparison of the track sizes observed by transmission electron microscopy and generated by different cluster and monoatomic ion beams supports the occurrence of a velocity effect in this material. DOI: 10.1103/PhysRevB.87.056102

The possibility of varying the beam parameters and applying the effect of a pre-etching treatment for poly(vinylidene fluoride) (PVDF) ion-track membranes was investigated with the goal of achieving enhanced track etching for effective control of the pore size and shape. Commercially available 25μm-thick PVDF films were irradiated at room temperature with swift heavy ions from the JAEA’s TIARA cyclotron and GSI’s UNILAC linear accelerator. Irradiation with a higher linear energy transfer (LET) beam gave faster track etching and larger pores, suggesting that the LET could be the most crucial factor determining the pore size. In-situ infra-red absorption and residual gas analyses shed light on the detailed chemistry of not only the ion-induced degradation, but also post-irradiation reactions. The pre-etching treatment effect involved oxidation of the unsaturated bonds within the latent track, which accelerated the chemical dissolution for efficient pore evolution. In other words, exposure to a gaseous oxidant, i.e., ozone, shortened the breakthrough time.

Color centers at a depth up to 3mm, far beyond the projected ranges of 8–11MeV/u 12C, 64Ni, 102Ru, 197Au, 208Pb, and 238U ions in LiF crystals, were observed after irradiation with high fluences (1012–1013ions/cm2). Possible coloration mechanisms (heavy particles, electrons, X- and γ-rays) are analyzed. Experimental results and theoretical estimations allowed presuming different mechanisms of the color center creation beyond the ranges for heavy and light projectiles. Characteristic X-ray emission or energetic primary knocked atoms can be a reason of deep coloration in the case of heavy ions, whereas light projectiles can originate the effect by the products of nuclear reactions (p, He and γ).

A CMOS inverter in 90 nm CMOS bulk technology was exposed to heavy ion radiation (Au-197) at a micro-beam facility. The targeted inverter occupies an area of 6 x 3 mu m(2). The resulting single event transient (SET) voltage pulses at the output were measured using an on-chip analogue sense amplifier. The output of the amplifier was recorded with a 15 GHz real-time oscilloscope. Depending on the location of the ion hits strongly different pulse shapes were observed.

The long-term "fate" of normal human cells after single hits of charged particles is one of the oldest unsolved issues in radiation protection and cellular radiobiology. Using a high-precision heavy-ion microbeam we could target normal human fibroblasts with exactly one or five carbon ions and measured the early cytogenetic damage and the late behaviour using single-cell cloning. Around 70% of the first cycle cells presented visible aberrations in mFISH after a single ion traversal, and about 5% of the cells were still able to form colonies. In one third of selected high-proliferative colonies we observed clonal (radiation-induced) aberrations. Terminal differentiation and markers of senescence (PCNA, p16) in the descendants of cells traversed by one carbon ion occurred earlier than in controls, but no evidence of radiation-induced chromosomal instability was found. We conclude that cells surviving single-ion traversal, often carrying clonal chromosome aberrations, undergo accelerated senescence but maintain chromosomal stability.

Final goal of the project FATAL is a simulation model which considers radiation induced effects, like single event transients (SETs) and single event upsets (SEUs), in asynchronous logic. Using this model, it will be possible to develop a design and simulation framework for designing radiation tolerant asynchronous logic. For synchronous logic such frameworks are already available. Synchronous logic is sensitive to single event effects (SEEs) at the clock edge only. Therefore it is sufficient to know the arising pulse widths of the SETs in order to design radiation tolerant synchronous logic [1]. In asynchronous logic there is no clock available. Thus it is sensitive to SEEs all the time. Furthermore, handshaking and data signals work with voltage transitions. Since SETs are nothing else than voltage transitions they can easily be misinterpreted as data or handshaking signals. To consider single event effects in a simulation model for asynchronous logic, it is necessary to know the exact shape of the arising SETs and the propagation of these pulses through the circuitry.