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Aurand B.,Lund University | Aurand B.,Helmholtzzentrum fur Schwerionenforschung GmbH | Elkin B.,Fraunhofer Institute For Grenzflachen Und Bioverfahrenstechnik | Heim L.-O.,Center for Smart Interfaces | And 8 more authors.
Journal of Polymer Science, Part B: Polymer Physics | Year: 2013

We report on the production and characterization of polymer-based ultra-thin (sub 10 nm) foils suited for experiments on laser-ion acceleration in the regime of radiation pressure acceleration. Beside the remarkable mechanical stability compared with commonly used diamond-like-carbon foils, a very homogeneous layer thickness and a small surface roughness have been achieved. We describe the technical issues of the production process as well as detailed studies of the mechanical stability and surface roughness tests. The capability of producing uniform targets of large area is essential for advanced laser-ion acceleration projects which are dealing with high repetition rate and extended measurement series, but might also be useful for other applications which require ultra-thin and freestanding substrates of high quality. © 2013 Wiley Periodicals, Inc.


Tessa C.La.,Helmholtzzentrum fur Schwerionenforschung GmbH | Berger T.,German Aerospace Center | Kaderka R.,Helmholtzzentrum fur Schwerionenforschung GmbH | Schardt D.,Helmholtzzentrum fur Schwerionenforschung GmbH | And 5 more authors.
Physics in Medicine and Biology | Year: 2014

Short- and long-term side effects following the treatment of cancer with radiation are strongly related to the amount of dose deposited to the healthy tissue surrounding the tumor. The characterization of the radiation field outside the planned target volume is the first step for estimating health risks, such as developing a secondary radioinduced malignancy. In ion and high-energy photon treatments, the major contribution to the dose deposited in the far-out-of-field region is given by neutrons, which are produced by nuclear interaction of the primary radiation with the beam line components and the patient's body. Measurements of the secondary neutron field and its contribution to the absorbed dose and equivalent dose for different radiotherapy technologies are presented in this work. An anthropomorphic RANDO phantom was irradiated with a treatment plan designed for a simulated 5 × 2 × 5 cm3 cancer volume located in the center of the head. The experiment was repeated with 25 MV IMRT (intensity modulated radiation therapy) photons and charged particles (protons and carbon ions) delivered with both passive modulation and spot scanning in different facilities. The measurements were performed with active (silicon-scintillation) and passive (bubble, thermoluminescence 6LiF:Mg, Ti (TLD-600) and 7LiF:Mg, Ti (TLD-700)) detectors to investigate the production of neutral particles both inside and outside the phantom. These techniques provided the whole energy spectrum (E 20 MeV) and corresponding absorbed dose and dose equivalent of photo neutrons produced by x-rays, the fluence of thermal neutrons for all irradiation types and the absorbed dose deposited by neutrons with 0.8 < E < 10 MeV during the treatment with scanned carbon ions. The highest yield of thermal neutrons is observed for photons and, among ions, for passively modulated beams. For the treatment with high-energy x-rays, the contribution of secondary neutrons to the dose equivalent is of the same order of magnitude as the primary radiation. In carbon therapy delivered with raster scanning, the absorbed dose deposited by neutrons in the energy region between 0.8 and 10 MeV is almost two orders of magnitude lower than charged fragments. We conclude that, within the energy range explored in this experimental work, the out-of-field dose from secondary neutrons is lowest for ions delivered by scanning, followed by passive modulation, and finally by high-energy IMRT photons. © 2014 Institute of Physics and Engineering in Medicine.


Kaderka R.,Helmholtzzentrum fur Schwerionenforschung GmbH | Schardt D.,Helmholtzzentrum fur Schwerionenforschung GmbH | Durante M.,Helmholtzzentrum fur Schwerionenforschung GmbH | Durante M.,TU Darmstadt | And 4 more authors.
Physics in Medicine and Biology | Year: 2012

This investigation focused on the characterization of the lateral dose fall-off following the irradiation of the target with photons, protons and carbon ions. A water phantom was irradiated with a rectangular field using photons, passively delivered protons as well as scanned protons and carbon ions. The lateral dose profile in the depth of the maximum dose was measured using an ion chamber, a diamond detector and thermoluminescence detectors TLD-600 and TLD-700. The yield of thermal neutrons was estimated for all radiation types while their complete spectrum was measured with bubble detectors during the irradiation with photons. The peripheral dose delivered by photons is significantly higher compared to both protons and carbon ions and exceeds the latter by up to two orders of magnitude at distances greater than 50mm from the field. The comparison of passive and active delivery techniques for protons shows that, for the chosen rectangular target shape, the former has a sharper penumbra whereas the latter has a lower dose in the far-out-of-field region. When comparing scanning treatments, carbon ions present a sharper dose fall-off than protons close to the target but increasing peripheral dose with increasing incident energy. For photon irradiation, the contribution to the out-of-field dose of photoneutrons appears to be of the same order of magnitude as the scattered primary beam. Charged particles show a clear supremacy over x-rays in achieving a higher dose conformality around the target and in sparing the healthy tissue from unnecessary radiation exposure. The out-of-field dose for x-rays increases with increasing beam energy because of the production of biologically harmful neutrons. © 2012 Institute of Physics and Engineering in Medicine.


Kumar R.,Inter University Accelerator Center | Doornenbal P.,Accelerator Centre | Jhingan A.,Inter University Accelerator Center | Bhowmik R.K.,Inter University Accelerator Center | And 14 more authors.
Physical Review C - Nuclear Physics | Year: 2010

Two consecutive Coulomb excitation experiments were performed to excite the 21+ states of Sn112,116 using a Ni58 beam. For Sn112 a B(E2) value of 0.242(8) e2,b2 has been determined relative to the known value of Sn116. The present value is more precise than previous measurements and shows a clear discrepancy from the expected parabolic dependence between the doubly magic nuclei Sn100 and Sn132. It implies that the reduced transition probabilities are not symmetric with respect to the midshell mass A=116. © 2010 The American Physical Society.


Celona L.,National Institute of Nuclear Physics, Italy | Gammino S.,National Institute of Nuclear Physics, Italy | Ciavola G.,National Institute of Nuclear Physics, Italy | Maimone F.,Helmholtzzentrum fur Schwerionenforschung GmbH | Mascali D.,National Institute of Nuclear Physics, Italy
Review of Scientific Instruments | Year: 2010

Coupling improvements between microwaves and plasmas are a key factor to design more powerful electron cyclotron resonance and microwave ion sources. On this purpose different activities have been undertaken by the INFN-LNS ion source team and a new approach was developed. Recent experiments confirmed the simulations, demonstrating that even in presence of a dense plasma, resonant modes are excited inside the cavity and the plasma dynamics depends on their structure. An overview of the coupling issues on microwave ion sources is also given along with a discussion on alternative coupling techniques. © 2010 American Institute of Physics.


Krauser J.,Hochschule Harz University of Applied Sciences | Nix A.-K.,University of Gottingen | Gehrke H.-G.,University of Gottingen | Hofsass H.,University of Gottingen | And 2 more authors.
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2012

Conducting ion tracks are formed when high-energy heavy ions (e.g. 1 GeV Au) pass through tetrahedral amorphous carbon (ta-C). These nanowires with a diameter of about 8 nm are embedded in the insulating ta-C matrix and of interest for various nanotechnological applications. Usually the overall conductivity of the tracks and the current/voltage characteristics (Ohmic or non-Ohmic) vary strongly from track to track, even when measured on the same sample, indicating that the track formation is neither complete nor homogeneous. To improve the track conductivity, doping of ta-C with N, B, Cu, or Fe is investigated. Beneficial changes in track conductivity after doping compete with a conductivity increase of the surrounding matrix material. Best results are achieved by incorporation of 1 at.% Cu, while for different reasons, the improvement of the tracks remains moderate for N, B, and Fe doping. Conductivity enhancement of the tracks is assumed to develop during the ion track formation process by an increased number of localized states which contribute to the current transport. © 2011 Elsevier B.V. All rights reserved.


Brantov A.V.,Russian Academy of Sciences | Bychenkov V.Yu.,Russian Academy of Sciences | Popov K.I.,University of Ottawa | Fedosejevs R.,University of Alberta | And 2 more authors.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2011

Based on 3D particle-in-cell (PIC) simulations a comparative analysis of laser-triggered proton generation from the interaction of short high-intensity laser pulses with ultrathin foils and dense gas jets has been performed. It has been shown that for ultra-relativistic laser intensities the use of low-density targets with near critical density (aerogel or dense gas jet) has no advantage in comparison with ultrathin foils in terms of maximum proton energy and spectrum quality. Utilization of mass-limited foils with submicron thickness demonstrates even greater superiority for overdense targets and allows one to produce monoenergetic proton beams with energies of hundreds of mega-electron-volts by using high-contrast laser pulses with energies of the order of tens of Joules. © 2011 Elsevier B.V.


Ogul R.,Selcuk University | Imal H.,Selcuk University | Ergun A.,Selcuk University | Buyukcizmeci N.,Selcuk University | And 2 more authors.
EPJ Web of Conferences | Year: 2015

We have investigated and interpreted the production cross sections and isotopic distributions of projectile-like residues in the reactions 124Sn + 124Sn and 112Sn + 112Sn at an incident beam energy of 1 GeV/nucleon measured with the FRS fragment separator at the GSI laboratory. For the interpretation of the data, calculations within the statistical multifragmentation model (SMM) for an ensemble of excited sources were performed with ensemble parameters. The possible modification of symmetry energy parameter, in the multifragmentation region at the low density and hot freeze-out environment, is studied. It is reconfirmed that a significant reduction of the symmetry energy term is found necessary to reproduce experimental results at these conditions. We have also found a decreasing trend of the symmetry energy for large neutron-rich fragments of low excitation energy which is interpreted as a nuclear-structure effect.


Krauser J.,Hochschule Harz University of Applied Sciences | Gehrke H.-G.,University of Gottingen | Hofsass H.,University of Gottingen | Trautmann C.,Helmholtzzentrum fur Schwerionenforschung GmbH | Weidinger A.,Helmholtz Center Berlin
Proceedings of the IEEE Conference on Nanotechnology | Year: 2011

In this work we combine ion track techniques to construct self-aligned vertical structures with nanometer dimensions. The main idea is to use multilayer targets and apply various etching techniques to create openings along the ion path. By irradiating such a multilayered sample including a tetrahedral amorphous carbon (ta-C) layer and a polymer film on top of the stack with swift heavy ions, the track in the polymer and the electrically conducting track in the ta-C layer are self-aligned and need no extra adjustment. Additional layers, e.g., metals or insulators which are little or not affected by the passage of the ions, can be inserted between the polymer resist and the ta-C film. Two appropriate device applications are proposed: a nano-sized field emission cathode and a two terminal quantum dot structure which might be completed to a transistor by adding a gate terminal. © 2011 IEEE.


PubMed | Helmholtzzentrum fur Schwerionenforschung GmbH
Type: Journal Article | Journal: Physics in medicine and biology | Year: 2012

This investigation focused on the characterization of the lateral dose fall-off following the irradiation of the target with photons, protons and carbon ions. A water phantom was irradiated with a rectangular field using photons, passively delivered protons as well as scanned protons and carbon ions. The lateral dose profile in the depth of the maximum dose was measured using an ion chamber, a diamond detector and thermoluminescence detectors TLD-600 and TLD-700. The yield of thermal neutrons was estimated for all radiation types while their complete spectrum was measured with bubble detectors during the irradiation with photons. The peripheral dose delivered by photons is significantly higher compared to both protons and carbon ions and exceeds the latter by up to two orders of magnitude at distances greater than 50mm from the field. The comparison of passive and active delivery techniques for protons shows that, for the chosen rectangular target shape, the former has a sharper penumbra whereas the latter has a lower dose in the far-out-of-field region. When comparing scanning treatments, carbon ions present a sharper dose fall-off than protons close to the target but increasing peripheral dose with increasing incident energy. For photon irradiation, the contribution to the out-of-field dose of photoneutrons appears to be of the same order of magnitude as the scattered primary beam. Charged particles show a clear supremacy over x-rays in achieving a higher dose conformality around the target and in sparing the healthy tissue from unnecessary radiation exposure. The out-of-field dose for x-rays increases with increasing beam energy because of the production of biologically harmful neutrons.

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