P. Apel - Academia.edu (original) (raw)

Papers by P. Apel

$Research paper thumbnail of The ultraviolet transmittance of porous VUV and X-ray diffraction filters$

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1991

ABSTRACT

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1994

ABSTRACT Solvent induced sensitization of heavy ion tracks in 19 mum polyethylene terephthalate f... more ABSTRACT Solvent induced sensitization of heavy ion tracks in 19 mum polyethylene terephthalate foils (Hostaphan RN19) is studied using dimethyl formamide (DMF) as swelling agent (thickness increase 5-7%) and argon gas as permeant. Due to the latent ion tracks acting as irrigation pipes the irradiated material swells one to two orders of magnitude faster than the original material. The effect of diffusion enhancement decreases with increasing linear energy transfer (LET) of the ions from about 8 for 15 MeV/u Ar to about 2-4 for 11.4 MeV/u Pb. The study of diffusive transfer of molecules along latent tracks enables an insight into sorption phenomena. It yields details concerning swelling, swelling equilibrium, and diffusion processes preceding track etching.

A comparative study of latent and etched track parameters in various polymers is performed with t... more A comparative study of latent and etched track parameters in various polymers is performed with the emphasis on the tracks of very heavy particles such as 238U ions in the energy range of 1–11.6 MeV/u. Samples of polyethylene terephthalate (PET), polypropylene (PP) and polysulphone (PSU) films were irradiated with heavy ions of various masses. The etching kinetics of the tracks

The structure of latent tracks in polyethylene terephthalate (PET) was studied using chemical etc... more The structure of latent tracks in polyethylene terephthalate (PET) was studied using chemical etching combined with a conductometric technique. Polymer samples were irradiated with Ar, Kr, Xe, Au, and U ions with energies in the range of 1 to 11.6 MeV/u. The etching kinetics of the tracks was investigated in the radii range 0±100 nm. The highly damaged track core manifests itself on the etching curves as a zone where the etch rate changes dramatically and reaches its minimum at a radius of a few nm. It was found that the track core radius is approximately proportional to (dE/ dx) 0X55 . The track core is surrounded by a halo. In the track halo the etching proceeds at a rate that slowly increases approaching a constant value. Cross linking of macromolecules causes reduction of the etch rate in the halo which extends up to distances exceeding 100 nm in the case of the heaviest ions. Measurable change of the etch rate at such large radii could not be predicted from the shape of the calculated spatial distributions of energy dissipated in tracks. Obviously, formation of the extended track halo is in¯uenced by the diusion of active intermediates from the track core to the polymer bulk. Ó 0168-583X/98/$ ± see front matter Ó 1998 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 -5 8 3 X ( 9 8 ) 0 0 4 4 5 -5

Track membrane (TM) technology is an example of industrial application of track etching technique... more Track membrane (TM) technology is an example of industrial application of track etching technique. Track-etch membranes o er distinct advantages over conventional membranes due to their precisely determined structure. Their pore size, shape and density can be varied in a controllable manner so that a membrane with the required transport and retention characteristics can be produced. The use of heavy ion accelerators made it possible to vary LET of track-forming particles, angle distribution of pore channels and pore lengths. So far the track formation and etching process has been studied in much detail for several polymeric materials. Today we understand determining factors and have numerous empirical data enabling us to manufacture any particular product based on polyethylene terephthalate (PET) or polycarbonate (PC) ÿlms. Pore shape can be made cylindrical, conical, funnel-like, or cigar-like at will. A number of modiÿcation methods has been developed for creating TMs with special properties and functions. Applications of "conventional" track membranes can be categorized into three groups: process ÿltration, cell culture, and laboratory ÿltration. The use in biology stands out among other areas. Nuclear track pores ÿnd diverse applications as model systems and as templates for the synthesis of micro-and nanostructures.

Transport properties of single asymmetric nanopores in polyethylene terephthalate (PET) and polyi... more Transport properties of single asymmetric nanopores in polyethylene terephthalate (PET) and polyimide (Kapton) membranes are investigated. The pores are produced by the track-etching technique based on irradiation of the polymer with heavy ions and subsequent chemical etching. Electrolytic conductivity measurements show that asymmetric pores in both polymeric materials rectify the ionic current. The PET and Kapton pores differ however significantly in their transient transport properties. The ion current through the PET nanopore fluctuates with the amplitudes reaching even 100% of the mean current, whereas nanopores in Kapton exhibit a stable current signal. We show that the transient properties of the pores depend on the chemical structure of the polymer as well as on the irradiation and etching procedures used in this work.

This report is a brief review of biological and medical applications of ion-track membranes. The ... more This report is a brief review of biological and medical applications of ion-track membranes. The review aims at informing nuclear physicists about alternative (i.e. nonfundamental-science) use of heavy ion accelerators such as production of micro-and nanoporous materials. The ion-track membranes produced this way are employed in life sciences and numerous technological applications. The author focuses on recent results from the Flerov laboratory in co-operation with other scientific institutions and industrial partners.

Creation of the DC60 Heavy Ion Cyclotron for the Interdisciplinary Scientiˇc and Research Complex... more Creation of the DC60 Heavy Ion Cyclotron for the Interdisciplinary Scientiˇc and Research Complex (ISRC) in Astana was started in early 2004. In the summer of 2006 the units of the cyclotron complex after their manufacturing and complex testing at the Flerov Laboratory of Nuclear Reactions, JINR, were delivered to Astana and assembled in the ISRC building. Physical start-up of the cyclotron took place in September 2006 and in December there were obtained accelerated and extracted heavy-ion beams in the whole of the projected range.

The complex based on the cyclotron IC100 of the Laboratory of Nuclear Reactions (JINR, Dubna, Rus... more The complex based on the cyclotron IC100 of the Laboratory of Nuclear Reactions (JINR, Dubna, Russia) provides industrial fabrication of nuclear filters. During modernization the cyclotron was equipped with superconducting ECR-ion source and axial injection system. The specialized beam channel with two coordinates scanning system and equipment for irradiation of polymer films has been installed in the implantation part of the complex. High intensity heavy ion beams of Ne, Ar, Fe, Kr, Xe, I, W have been accelerated to 1 MeV/nucleon energy. The investigation of irradiated crystals features, irradiation of different polymer films have been provided. Also few thousands square meters of track films with holes in the wide range of densities have been produced. The cyclotron based complex is capable to solve different kinds of scientific and applied problems as well.

Surface Science, 2003

Conically shaped pores have been prepared in polyethylene terephthalate (PET) and polyimide foils... more Conically shaped pores have been prepared in polyethylene terephthalate (PET) and polyimide foils by applying the track-etching technique. For this purpose, a thin polymer foil was penetrated by a single heavy ion (e.g. Au, Bi, U) of total kinetic energy of several hundred MeV to some GeV, followed by preferential chemical etching of the ion track. Asymmetric etching conditions allowed the preparation of charged pores of conical shape, similar to biological voltagesensitive channels. The nanopores in PET and polyimide behave as ion current rectifiers where the preferential direction of the cation flow is from the narrow entrance towards the wide aperture of the pore. The PET pore shows voltagedependent ion current fluctuations with opening and closing kinetics similar to voltage-gated biological ion channels. In contrast to PET, the polyimide nanopore exhibits a stable ion current signal. We discuss the possibility of using the synthetic nanopores as model for voltage-gated biochannels.

Radiation Measurements, 2004

Radiation Measurements, 1999

The structure of latent tracks in polyethylene terephthalate is studied using chemical etching co... more The structure of latent tracks in polyethylene terephthalate is studied using chemical etching combined with a conductometric technique. Geometrical parameters of the latent tracks for the range of the electronic energy loss (dE/dx) between 3 to 24 keV/nm are estimated. The dependence of the track core and track halo size on the energy loss is analyzed.

International Journal of Radiation Applications and Instrumentation. Part D. Nuclear Tracks and Radiation Measurements, 1990

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2010

ABSTRACT We describe a system for fabricating prescribed numbers of ion track nanochannels and na... more ABSTRACT We describe a system for fabricating prescribed numbers of ion track nanochannels and nanowires from a few hundred down to one. It consists of two parts: first, a mobile tape transport system, which, in connection with an ion beam from a heavy-ion accelerator (nuclear charge Z above 18 and specific energy between 1 and 10 MeV/nucleon) tuned down to low flux density by means of defocusing and a set of sensitive fluorescence screens, can fabricate a series of equidistant irradiation spots on a tape, whereby each spot corresponds to a preset number of ion tracks. The tape transport system uses films of 36 mm width and thicknesses between 5 and 100 μm. The aiming precision of the system depends on the diameter of the installed beam-defining aperture, which is between 50 and 500 μm. The distance between neighboring irradiation spots on the tape is variable and typically set to 25 mm. After reaching the preset number of ion counts the irradiation is terminated, the tape is marked and moved to the next position. The irradiated frames are punched out to circular membranes with the irradiation spot in the center. The second part of the setup is a compact conductometric system with 10 picoampere resolution consisting of a computer controlled conductometric cell, sealing the membrane hermetically between two chemically inert half-chambers containing electrodes and filling/flushing openings, and is encased by an electrical shield and a thermal insulation. The ion tracks can be etched to a preset diameter and the system can be programmed to electroreplicate nanochannels in a prescribed sequence of magnetic/nonmagnetic metals, alloys or semiconductors. The goal of our article is to make the scientific community aware of the special features of single-ion fabrication and to demonstrate convincingly the significance of controlled etching and electro-replication.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2003

This paper is a review about methods of polymeric material modification based on the irradiation ... more This paper is a review about methods of polymeric material modification based on the irradiation with accelerated heavy ions in the 1-10 MeV/u energy range. Chemical etching of ion tracks in polymers is a method which is widely used in the fabrication of micro-and nanostructures with pre-determined characteristics. Micro-and ultrafiltration membranes produced in this way and known as ''track-etch membranes'' have found several niches in the market since the seventies. This is an example of mature technology based on irradiation with swift ions. Apart from the membrane technology, the ion track pores find diverse applications as templates for the synthesis of micro-and nanowires and tubes, textured surfaces and bodies with special optical properties. Some recent achievements and promising ideas utilizing swift ion beams are presented.