Protonnyalábos mikromegmunkálás = Proton beam Micromachinig

A téma keretében a mikromegmunkálás módszerét telepítettük az ATOMKI pásztázó proton mikroszondájához. Második lépésben különböző nyomdetektor és más reziszt anyagokat vizsgáltunk a mikromegmunkálás szempontjából. A megmunkált anyagok különböző jellemzőit vizsgáltuk a besugárzási paraméterek függvényében. Az előállított eszközök (mikrostruktúrák) alkalmazási lehetőségeit fel kívántuk kutatni, mikrostruktúrákat állítottuk elő demonstrációs és konkrét alkalmazási célból. A világon második kutatócsoport lettünk e témában, szerepünk azonban nem másodrendű. Kihasználva saját adottságainkat, a nemzetközi irodalomhoz új kutatási eredményekkel járultunk hozzá. Az ATOMKI pásztázó proton mikroszondája így egy új, perspektivikus alkalmazási területet nyert. | We have installed the Proton Beam Micromachining (PBM) / P-beam Writing (PBW) method on the Scanning Nuclear Microprobe of ATOMKI. We have investigated various solid state nuclear track detector and other resist materials for micromachining properties. We have characterized various properties of materials as a function of irradiation parameters. We have explored the potential application areas of the produced microstructures. We have created products for demonstration and real application purposes. We became the second research group in the world in this field, but our role is not of secondary importance. Exploiting our resources, we have added new scientific results to the literature. The Scanning Nuclear Microprobe of ATOMKI has gained a new, prosperous application area

Cross section measurement of the astrophysically important 17O(p,gamma)18F reaction in a wide energy range

The 17O(p,g)18F reaction plays an important role in hydrogen burning processes in different stages of stellar evolution. The rate of this reaction must therefore be known with high accuracy in order to provide the necessary input for astrophysical models. The cross section of 17O(p,g)18F is characterized by a complicated resonance structure at low energies. Experimental data, however, is scarce in a wide energy range which increases the uncertainty of the low energy extrapolations. The purpose of the present work is therefore to provide consistent and precise cross section values in a wide energy range. The cross section is measured using the activation method which provides directly the total cross section. With this technique some typical systematic uncertainties encountered in in-beam gamma-spectroscopy experiments can be avoided. The cross section was measured between 500 keV and 1.8 MeV proton energies with a total uncertainty of typically 10%. The results are compared with earlier measurements and it is found that the gross features of the 17O(p,g)18F excitation function is relatively well reproduced by the present data. Deviation of roughly a factor of 1.5 is found in the case of the total cross section when compared with the only one high energy dataset. At the lowest measured energy our result is in agreement with two recent datasets within one standard deviation and deviates by roughly two standard deviations from a third one. An R-matrix analysis of the present and previous data strengthen the reliability of the extrapolated zero energy astrophysical S-factor. Using an independent experimental technique, the literature cross section data of 17O(p,g)18F is confirmed in the energy region of the resonances while lower direct capture cross section is recommended at higher energies. The present dataset provides a constraint for the theoretical cross sections.Comment: Accepted for publication in Phys. Rev. C. Abstract shortened in order to comply with arxiv rule

Tilted pillar array fabrication by the combination of proton beam writing and soft lithography for microfluidic cell capture Part 2: Image sequence analysis based evaluation and biological application

As a continuation of our previously published work, this paper presents a detailed evaluation of a microfabricated cell capture device utilizing a doubly tilted micropillar array. The device was fabricated using a novel hybrid technology based on the combination of proton beam writing and conventional lithography techniques. Tilted pillars offer unique flow characteristics and support enhanced fluidic interaction for improved immuno-affinity based cell capture. The performance of the microdevice was evaluated by an image sequence analysis based in-house developed single cell tracking system. Individual cell tracking allowed in-depth analysis of the cell-chip surface interaction mechanism from hydrodynamic point of view. Simulation results were validated by using the hybrid device and the optimized surface functionalization procedure. Finally, the cell capture capability of this new generation microdevice was demonstrated by efficiently arresting cells from a HT29 cellline suspension

Transverse and secondary voltages in BSCCO single crystals

Multicontact configuration is one of the most powerful arrangements for electrical transport measurements applied to study vortex phase transition and vortex phase dimensionality in strongly anisotropic high-Tc superconducting materials. In this paper we present electrical transport measurements using a multiterminal configuration, which prove both the existence of guided vortex motion in BSCCO single crystals near the transition temperature and that secondary voltage in zero external magnetic field is induced by thermally activated vortex loop unbinding. The phase transition between the bound and unbound states of the vortex loops was found to be below the temperature where the phase coherence of the superconducting order parameter extends over the whole volume of the sample. We show experimentally that 3D/2D phase transition in vortex dimensionality is a length-scale-dependent layer decoupling process and takes place simultaneously with the 3D/2D phase transition in superconductivity at the same temperature.Comment: 8 pages, 5 figures, to be published in Physica

Can the ions be guided with MeV/amu energies? The case of the 1 MeV proton microbeam

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Observation of the X17 anomaly in the decay of the Giant Dipole Resonance of 8^8Be

Angular correlation spectra of $e^+e^-$ pairs produced in the $^{7}$Li($p$,$\gamma$)$^{8}$Be nuclear reaction were studied at a proton beam energy of $E_p$~=~4.0~MeV, which corresponds to the excitation energy of the Giant Dipole Resonance (GDR) in $^8$Be. The spectra measured show a peak like anomaly at 120$^\circ$ and a broader anomaly also above 140$^\circ$. Both anomalies could consistently be described by assuming that the same hypothetical X17 particle was created both in the ground-state transition and in the transition going to the broad ($\Gamma$=1.5~MeV), first excited state in $^8$Be. The invariant mass of the particle, which was derived to be $m_Xc^2 = 16.95 \pm 0.48$(stat.)~MeV, agrees well with our previously published values.Comment: 5 pages, 7 figures. arXiv admin note: text overlap with arXiv:2209.1079

Direct surface patterning of amorphous chalcogenide layers with high- energy H+ and He+ ion beams

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Bombardment of CO ice by cosmic rays: I. Experimental insights into the microphysics of molecule destruction and sputtering

We present a dedicated experimental study of microscopic mechanisms controlling radiolysis and sputtering of astrophysical ices due to their bombardment by cosmic ray ions. Such ions are slowed down due to inelastic collisions with bound electrons, resulting in ionization and excitation of ice molecules. In experiments on CO ice irradiation, we show that the relative contribution of these two mechanisms of energy loss to molecule destruction and sputtering can be probed by selecting ion energies near the peak of the electronic stopping power. We have observed a significant asymmetry, both in the destruction cross section and the sputtering yield, for pairs of ion energies corresponding to same values of the stopping power on either side of the peak. This implies that the stopping power does not solely control these processes, as usually assumed in the literature. Our results suggest that electronic excitations represent a significantly more efficient channel for radiolysis and, possibly, also for sputtering of CO ice. We also show that the charge state of incident ions as well as the rate for CO$^+$ production in the ice have negligible effect on these processes.Comment: Accepted for publication in Ap