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Purpose To evaluate the impact of beam quality in terms of distal fall off DFO, 90 10 and lateral penumbra LP, 80 20 of single beam ocular proton therapy OPT and to derive resulting ideal requirements for future systems. Methods Nine different beam models with DFO varying between 1 and 4 mm and LP between 1 and 4 mm were created. Beam models were incorporated into the RayStation with RayOcular treatment planning system version 10 B RaySearch Laboratories, Stockholm, Sweden . Each beam model was applied for eight typical clinical cases, covering different sizes and locations of uveal melanoma. Plans with and without an additional wedge were created, resulting in 117 plans with a total prescribed median dose of 60 Gy RBE to the clinical target volume. Treatment plans were analyzed in terms of V20 V80 penumbra volume, D1 dose to 1 of the volume for optic disc and macula, optic nerve V30 volume receiving 30 Gy RBE , i.e., 50 of prescription , as well as average dose to lens and ciliary body. An LP dependent aperture margin was based on estimated uncertainties, ranging from 1.7 to 4.0 mm. Results V20 V80 showed a strong influence by LP, while DFO was less relevant. The optic disc D1 reached an extra dose of up to 3000 cGy RBE , comparing the defined technical limit of DFO LP 1 mm with DFO 3 mm LP 4 mm. The latter may result from a pencil beam scanning PBS system with static apertures. Plans employing a wedge showed an improvement for organs at risk sparing. Conclusion Plan quality is strongly influenced by initial beam parameters. The impact of LP is more pronounced when compared to DFO. The latter becomes important in the treatment of posterior tumors near the macula, optic disc or optic nerve. The plan quality achieved by dedicated OPT nozzles in single or double scattering design might not be achievable with modified PBS systems

Background and aimsThe HZB Cyclotron facility is able to deliver proton FLASH irradiation, providing beamtime to Charité – Universitätsmedizin Berlin for in vivo and in vitro experiments. For these studies, a spread-out Bragg peak with a maximum dose rate of 100 Gy/s has been applied within 200 ms at a maximum energy of 68 MeV. Since then, various system upgrades have been implemented with the aim to increase the achieved dose rate and shorten the irradiation time. The involved components and their performance are presented below. MethodsBetween the cyclotron and its injector, an electrostatic deflector has been installed, which is controlled by an FPGA board and acts as an adjustable beam shutter, providing irradiation times down to 1 ms. Within such short durations, the delivered beam intensity can be safely increased without damaging the vacuum window at the beam exit and without reaching the radiation safety limits. The increased dose rates from a mm-focused beam are then measured by an Advanced Markus Chamber (PTW-Freiburg, Germany) and monitored by an in-house developed transparent ionization chamber, connected to a UNIDOS webline electrometer (PTW-Freiburg, Germany). ResultsBoth ionization chambers have shown a linear response with respect to the beam current for dose rates up to 4 kGy/s. An irradiation time of 1 ms has been achieved with a statistical fluctuation of 4%, while the clinical requirement of ConclusionsThe updated FLASH capabilities of the HZB Cyclotron enable a reliable delivery, measurement and monitoring of proton dose rates in the order of several kGy/s within few ms. In combination with the available 3D range modulator, the parameter space for systematic clinical experiments is broadened remarkably.

Purpose: Eye-dedicated proton therapy (PT) facilities are used to treat malignant intraocular lesions, especially uveal melanoma (UM). The first commercial ocular PT beamline from Varian was installed in the Netherlands. In this work, the conceptual design of the new eyeline is presented. In addition, a comprehensive comparison against five PT centers with dedicated ocular beamlines is performed, and the clinical impact of the identified differences is analyzed. Material/Methods: The HollandPTC eyeline was characterized. Four centers in Europe and one in the United States joined the study. All centers use a cyclotron for proton beam generation and an eye-dedicated nozzle. Differences among the chosen ocular beamlines were in the design of the nozzle, nominal energy, and energy spectrum. The following parameters were collected for all centers: technical characteristics and a set of distal, proximal, and lateral region measurements. The measurements were performed with detectors available in-house at each institution. The institutions followed the International Atomic Energy Agency (IAEA) Technical Report Series (TRS)-398 Code of Practice for absolute dose measurement, and the IAEA TRS-398 Code of Practice, its modified version or International Commission on Radiation Units and Measurements Report No. 78 for spread-out Bragg peak normalization. Energy spreads of the pristine Bragg peaks were obtained with Monte Carlo simulations using Geant4. Seven tumor-specific case scenarios were simulated to evaluate the clinical impact among centers: small, medium, and large UM, located either anteriorly, at the equator, or posteriorly within the eye. Differences in the depth dose distributions were calculated. Results: A pristine Bragg peak of HollandPTC eyeline corresponded to the constant energy of 75 MeV (maximal range 3.97 g/cm2 in water) with an energy spread of 1.10 MeV. The pristine Bragg peaks for the five participating centers varied from 62.50 to 104.50 MeV with an energy spread variation between 0.10 and 0.70 MeV. Differences in the average distal fall-offs and lateral penumbrae (LPs) (over the complete set of clinically available beam modulations) among all centers were up to 0.25 g/cm2, and 0.80 mm, respectively. Average distal fall-offs of the HollandPTC eyeline were 0.20 g/cm2, and LPs were between 1.50 and 2.15 mm from proximal to distal regions, respectively. Treatment time, around 60 s, was comparable among all centers. The virtual source-to-axis distance of 120 cm at HollandPTC was shorter than for the five participating centers (range: 165–350 cm). Simulated depth dose distributions demonstrated the impact of the different beamline characteristics among institutions. The largest difference was observed for a small UM located at the posterior pole, where a proximal dose between two extreme centers was up to 20%. Conclusions: HollandPTC eyeline specifications are in accordance with five other ocular PT beamlines. Similar clinical concepts can be applied to expect the same high local tumor control. Dosimetrical properties among the six institutions induce most likely differences in ocular radiation-related toxicities. This interinstitutional comparison could support further research on ocular post-PT complications. Finally, the findings reported in this study could be used to define dosimetrical guidelines for ocular PT to unify the concepts among institutions.

PURPOSE Recent studies indicate that FLASH irradiation, which involves ultra-high dose rates in a short time window (usually >40 Gy/s in

Background and aims In the pursuit of optimal parameters for FLASH irradiation, all components involved in the beam delivery should be compatible with requirements spread in an extreme and wide unexplored regime. Aiming for minimal total irradiation times with modulated proton beams, which deliver a flat depth-dose distribution along tumors, a static range modulator has been developed to accommodate ultra-short beam durations regardless of their time structure. The design goals were set to match the functionality of the rotating wheel used for in-vivo and in-vitro FLASH investigations at HZB. Methods Having the form of a ridge filter extended to an additional dimension, a hexagonal-pyramid pattern was configured to an incoming beam of 23 MeV energy with > 1 mm radius, in order to create a 6 mm uniform field with a flat dose range of 5 mm at the target. The manufacturing was done with a 3D printer using VeroWhite, a material similar to PMMA. The lateral and distal dose distribution of both modulators were measured using a Markus Chamber (PTW-Freiburg, Germany) in a water phantom and a radioluminescent screen mounted in front of CCD camera, respectively. Results The developed modulator created very flat dose distributions as designed, with negligible differences to the reference rotating wheel. The positioning tolerances were evaluated as relatively relaxed, with offsets of 2 cm and an angle of 5 degrees not compromising the desired performance. Conclusions The developed static modulator allows systematic proton FLASH studies on small organs using a broad range of timing schemes, disentangled from temporal and spatial incoherencies.

Nuclear deexcitation lines are regularly observed in the $\ensuremath{\gamma}$-ray emission spectra of strong solar flares. The most prominent lines are produced by interactions of protons and $\ensuremath{\alpha}$ particles, accelerated up to hundreds of MeV, with abundant nuclei of the solar atmosphere. Analysis and interpretation of these lines, which carry valuable information on the solar flare properties, need cross-section data for the $\ensuremath{\gamma}$-ray line emission in these interactions for a wide particle energy range. To this purpose, we measured the $\ensuremath{\gamma}$-ray emission in interactions of $\ensuremath{\alpha}$-particle beams of ${E}_{\ensuremath{\alpha}}=50\text{--}90$ MeV with target foils of C, Mg, Si, and Fe at the center for proton therapy of the Helmholtz-Zentrum Berlin. Setups of three high-purity Ge detectors and one $\mathrm{La}{\mathrm{Br}}_{3}$:Ce detector have been employed to detect the $\ensuremath{\gamma}$ rays in two experiment campaigns. Relatively large distances of the detectors from the target and pulsed beams with sub-ns-wide pulses allowed the separation of beam-induced prompt $\ensuremath{\gamma}$-ray emission from the targets from other $\ensuremath{\gamma}$ rays and neutron-induced background. $\ensuremath{\gamma}$-ray production cross sections for about 60 deexcitation lines from excited target nuclei or reaction products have been determined. For the strongest deexcitation lines from the major target isotopes, $^{12}\mathrm{C}$, $^{24}\mathrm{Mg}$, $^{28}\mathrm{Si}$, $^{56}\mathrm{Fe}$, there are now measured cross-section data from reaction threshold to ${E}_{\ensuremath{\alpha}}=90$ MeV that can be directly used for astrophysical applications like solar flares. Comparison of the results with a cross-section compilation for strong $\ensuremath{\gamma}$-ray lines in solar flare emissions and the predictions of the talys nuclear reaction code were done. They underline the importance of cross-section determinations at accelerator laboratories for the establishment of an accurate cross-section data base in a wide projectile energy range.

Amorphous silicon-based thin-film minimodules have been irradiated with 68MeV protons up to a dose of 1×1012 protons/cm2. During the irradiation, the solar cell current under short circuit conditions, due to the photogeneration of charge carriers by the low-intensity room light and the radiation-induced generation of charge carriers, has been measured. Whereas the degradation of the photo-induced current can be continuously monitored during the experiment, the smaller radiation-induced current is only visible in current discontinuities at the beginning and the end of the radiation period. In our experiment, we measured a very similar decrease in the photo- and the radiation-induced current, both due to the proton irradiation. Therefore, we can infer that the degradation of the solar cells’ photoelectrical properties is mainly due to the degradation of the amorphous silicon active material and only to a smaller content to the glass substrate’s optical transmission properties. Directly after irradiation, we observed a continuous recovery of the photo-induced current, due to the room-temperature annealing of the electronic defects created in the amorphous silicon absorber layer.

Materials analysis with ion beams exploits the interaction of ions with the electrons and nuclei in the sample. Among the vast variety of possible analytical techniques available with ion beams, this chapter confines itself to ion beam analysis with hydrogen ions having an energy of about 70 MeV. The interaction of these ions with the electrons in the sample produces holes in the inner electronic shells of the sample atoms, which recombine and emit X-rays characteristic of the element in question. Particle-induced X-ray emission is shown to be a fast technique for the analysis of elements with an atomic number above 11.

The impact of high energy proton radiation, as would be encountered in highly eccentric and Europa orbits, on ultra-thin GaAs solar cells was studied. The cells were irradiated with 68 MeV protons at fluences of 2 × 1012 cm−2 and 1 × 1013cm−2. Cathodoluminescence and dark I-V were used to evaluate the variation of defect density and J 02 with fluence, respectively. The applicability of cathodoluminescence to the study of radiation damage in photovoltaic devices is discussed.

Ultra-thin (less than 100 nm) photovoltaics for space power applications are proposed due to their intrinsic radiation tolerance [1]. They are a potentially enabling technology for space missions in high radiation environments such as Highly Elliptical Earth Orbits (HEO) and the orbits of Jupiter's scientifically interesting moon, Europa. GaAs solar cells with an 80 nm active layer were designed, fabricated and tested under 68 MeV proton irradiation. The results of electrical characterisation before and after proton beam exposure at two different fluences shows their tolerance to these harsh conditions.

Summary Monolithic [Cs0.05(MA0.17FA0.83)0.95]Pb(I0.83Br0.17)3/Cu(In,Ga)Se2 (perovskite/CIGS) tandem solar cells promise high performance and can be processed on flexible substrates, enabling cost-efficient and ultra-lightweight space photovoltaics with power-to-weight and power-to-cost ratios surpassing those of state-of-the-art III-V semiconductor-based multijunctions. However, to become a viable space technology, the full tandem stack must withstand the harsh radiation environments in space. Here, we design tailored operando and ex situ measurements to show that perovskite/CIGS cells retain over 85% of their initial efficiency even after 68 MeV proton irradiation at a dose of 2 × 1012 p+/cm2. We use photoluminescence microscopy to show that the local quasi-Fermi-level splitting of the perovskite top cell is unaffected. We identify that the efficiency losses arise primarily from increased recombination in the CIGS bottom cell and the nickel-oxide-based recombination contact. These results are corroborated by measurements of monolithic perovskite/silicon-heterojunction cells, which severely degrade to 1% of their initial efficiency due to radiation-induced recombination centers in silicon., Graphical Abstract, Highlights • Halide perovskite sub-cells exhibit strong proton irradiation resiliency • Novel operando characterization distinguishes degradation of individual sub-cells • Perovskite/CIGS tandem solar cells retain 85% of their initial efficiency after irradiation • Perovskite/SHJ tandem solar cells degrade to 1% of their initial efficiency after irradiation, Context & Scale Monolithic perovskite/silicon and perovskite/CIGS tandem solar cells could facilitate large-scale decarbonization of the power sector, provided their long-term stability is proven. In this work, we test the stability of both technologies under high-energy proton irradiation. While this mimics the radiation environment in space, our versatile operando and ex situ methodology is also suitable for studying the long-term stability of multijunction solar cells for terrestrial applications. We find that perovskite/silicon tandem solar cells are unsuitable for space, whereas perovskite/CIGS tandems are radiation-hard, promising cheap, flexible, and ultra-lightweight space photovoltaics. Both the growing demand for smaller, cheaper satellites and the privatization of space exploration are revolutionizing space economics, providing an ideal niche for the commercialization of this new technology until the levelized cost-of-electricity can compete with current terrestrial photovoltaics., We propose and test monolithic perovskite/CIGS tandem solar cells for readily stowable, ultra-lightweight space photovoltaics. We design operando and ex situ measurements to show that perovskite/CIGS tandem solar cells retain over 85% of their initial power-conversion efficiency after high-energy proton irradiation. While the perovskite sub-cell is unaffected after this bombardment, we identify increased non-radiative recombination in the CIGS bottom cell and nickel-oxide-based recombination layer. By contrast, monolithic perovskite/silicon-heterojunction cells degrade to 1% of their initial efficiency due to radiation-induced defects in silicon.

Highly efficient perovskite based solar cells have the potential to be a game-changing solar array technology for space applications that can be flexible, truly roll-able, ultra-lightweight and highly stowable. Outside earth's magnetic field, however, ionizing radiation causes localized defect states that accumulate and ultimately cause the failure of electronic devices. This study, assesses the radiation hardness of the widely used triple cation based perovskite absorber material, namely Cs0.05MA0.17FA0.83Pb(I0.83Br0.17)3 employing 20 and 68 MeV proton irradiation. Therefore, in situ measurements of the degradation of the proton induced current as well as the photovoltaic performance during proton irradiation are used as two independent metrics. Both measurements suggest that triple cation perovskites even exceed the radiation hardness of SiC, which is a material often proposed to possess an excellent radiation hardness. Our optimized Cs0.05MA0.17FA0.83Pb(I0.83Br0.17)3 based space solar cells reach efficiencies of 18.8% under AM0 illumination and maintain 95% of their initial efficiency even after irradiation with protons at an energy 68 MeV and a total dose of 1012 p per cm2. Degradation under 20 MeV proton irradiation is even lower. Despite the negligible impact on solar cell device performance, this study identifies that proton irradiation is changing the recombination kinetics under low excitation densities profoundly. Dark capacitance–voltage and current–voltage characteristics, photoluminescence spectra as well as photoluminescence and Voc decays are analyzed in depth. Surprisingly, two fold prolonged PL and Voc decay times are observed after proton irradiation. Often, such prolongations are attributed to a reduced charge recombination. Our kinetic model, precisely describing the observed time evolution after photoexcitation, however, establishes the prolonged release of trapped minority charge carriers from proton-radiation induced trap states.

Funder: European Research Council; Id: http://dx.doi.org/10.13039/501100000781, Funder: Engineering and Physical Sciences Research Council; Id: http://dx.doi.org/10.13039/501100000266, Funder: European Union's Horizon 2020, Radiation‐resistant but cost‐efficient, flexible, and ultralight solar sheets with high specific power (W g−1) are the “holy grail” of the new space revolution, powering private space exploration, low‐cost missions, and future habitats on Moon and Mars. Herein, this study investigates an all‐perovskite tandem photovoltaic (PV) technology that uses an ultrathin active layer (1.56 µm) but offers high power conversion efficiency, and discusses its potential for high‐specific‐power applications. This study demonstrates that all‐perovskite tandems possess a high tolerance to the harsh radiation environment in space. The tests under 68 MeV proton irradiation show negligible degradation (22%. Using high spatial resolution photoluminescence (PL) microscopy, it is revealed that defect clusters in GaAs are responsible for the degradation of current space‐PV. By contrast, negligible reduction in PL of the individual perovskite subcells even after the highest dose studied is observed. Studying the intensity‐dependent PL of bare low‐gap and high‐gap perovskite absorbers, it is shown that the VOC, fill factor, and efficiency potentials remain identically high after irradiation. Radiation damage of all‐perovskite tandems thus has a fundamentally different origin to traditional space PV.

Cross sections for the strongest gamma-ray emission lines produced in alpha-particle reactions with C, Mg, Si, Fe have been measured in the range E_alpha = 50 - 90 MeV at the center for proton therapy at the Helmholtz-Zentrum Berlin. Data for more than 60 different gamma-ray lines were determined, with particular efforts for lines that are in cross section compilations/evaluations with astrophysical purpose, and where data exist at lower projectile energies. The data are compared with predictions of a modern nuclear reaction code and cross-section curves of the latest evaluation for gamma-ray line emission in accelerated-particle interactions in solar flares., Comment: 5 pages, 5 figures, contribution to the XXIII International School on Nuclear Physics, Neutron Physics and Applications, Varna, Bulgaria, September 22-28, 2019

Purpose To assess the planning, treatment, and follow-up strategies worldwide in dedicated proton therapy ocular programs. Methods and Materials Ten centers from 7 countries completed a questionnaire survey with 109 queries on the eye treatment planning system (TPS), hardware/software equipment, image acquisition/registration, patient positioning, eye surveillance, beam delivery, quality assurance (QA), clinical management, and workflow. Results Worldwide, 28,891 eye patients were treated with protons at the 10 centers as of the end of 2014. Most centers treated a vast number of ocular patients (1729 to 6369). Three centers treated fewer than 200 ocular patients. Most commonly, the centers treated uveal melanoma (UM) and other primary ocular malignancies, benign ocular tumors, conjunctival lesions, choroidal metastases, and retinoblastomas. The UM dose fractionation was generally within a standard range, whereas dosing for other ocular conditions was not standardized. The majority (80%) of centers used in common a specific ocular TPS. Variability existed in imaging registration, with magnetic resonance imaging (MRI) rarely being used in routine planning (20%). Increased patient to full-time equivalent ratios were observed by higher accruing centers ( P =.0161). Generally, ophthalmologists followed up the post–radiation therapy patients, though in 40% of centers radiation oncologists also followed up the patients. Seven centers had a prospective outcomes database. All centers used a cyclotron to accelerate protons with dedicated horizontal beam lines only. QA checks (range, modulation) varied substantially across centers. Conclusions The first worldwide multi-institutional ophthalmic proton therapy survey of the clinical and technical approach shows areas of substantial overlap and areas of progress needed to achieve sustainable and systematic management. Future international efforts include research and development for imaging and planning software upgrades, increased use of MRI, development of clinical protocols, systematic patient-centered data acquisition, and publishing guidelines on QA, staffing, treatment, and follow-up parameters by dedicated ocular programs to ensure the highest level of care for ocular patients.

The influence of high energy Proton irradiation on the performance of Silicon photodiodes is investigated using two illuminated devices connected in series as power supply of a ring-oscillator realized with commercially available CMOS NAND gates and monitoring the output frequency. In order to consider the degradation of a single solar cell a 19-stage ring-oscillator fabricated in a standard CMOS process is operated. The circuit provides an integrated frequency divider and an output buffer, and stable voltage-to-frequency conversion is obtained for supply voltages provided by the photodiode down to 300mV.

Thin film tandem solar cells, comprising of a perovskite top device and a radiation hard CIGS bottom solar cell would be attractive for space applications since they can be lightweight, flexible, and efficient. In this work, the ability to withstand the harsh radiation environment in space, consisting mainly of high-energy protons is demonstrated. In-situ measurements of the J-V characteristics during proton irradiation with a proton energy of 68 MeV show that organic-inorganic perovskites are radiation hard. The investigated CH3NH3PbI3 based perovskite solar cells possess a negligible degradation for proton doses of up to 1012 p cm-2. [1,2]This exceeds the proton dose at which c-Si degrades by almost 3 orders of magnitude. Even more surprising is the observation that the solar cell performance improves with time after the proton irradiation is terminated. Hence, the localized defects caused by proton irradiation are metastable and vanish with time. In addition, proton irradiation partially compensated the photo-degradation effect of the perovskite solar cells. Compared to untreated devices the open circuit voltage and the fill factor improved. This is mainly attributed to smaller recombination losses due to a decrease of the density of localized defects. Simultaneously, proton irradiation caused the formation of shallow defects, which act as doping centers. The observed radiation hardness and self-healing capabilities render inorganic-organic perovskite absorbers highly attractive for space applications. [1] F. Lang, N. H. Nickel, J. Bundesmann, S. Seidel, A. Denker, S. Albrecht, V. V. Brus, J. Rappich, B. Rech, G. Landi, H. C. Neitzert, Adv. Mater. 2016, 28, 8726. [2] V. V Brus, F. Lang, J. Bundesmann, S. Seidel, A. Denker, B. Rech, G. Landi, H. C. Neitzert, J. Rappich, N. H. Nickel, Adv. Electron. Mater. 2017, 3, 1600438.

Perovskite solar cells have been shown to be of extraordinary radiation hardness, considering high energetic 68 MeV proton irradiation with doses up to 1013 p cm amp; 8722;2. In this study electrical and photoelectrical properties of perovskite solar cells with and without proton irradiation are analyzed in detail. The results reveal that proton irradiation improves the open circuit voltage, fill factor, and recombination lifetime of photogenerated charge carriers in perovskite solar cells. These enhancements are mainly a result of the lower nonradiative recombination losses in the proton irradiated devices. The proton treatment creates shallow traps, which may be associated with the proton induced point defects due to the displacements of atoms in the inorganic Pb I framework, which act as unintentional doping sources and partially compensate deep traps originated from the photodegradation of methylammonium molecules

Autoradiography uses a photographic film or imaging plate which are placed in direct contact with a painting after irradiation by slow neutrons. The pigments become radioactive after the interaction with the neutron beam and the emitted radiation (gammas, X-rays and electrons, so called beta-rays) is registered in the film or plate. The blackening of the film is mainly due to the beta-rays because the gamma rays are high energetic and hardly interact with the film. In this way the obtained picture can be called beta-radiography, but since the radioactive elements in the painting itself are the source of beta rays, the technique is called “autoradiography.” In addition gamma spectrometry can be applied for detecting the emitted radiation from activated elements and by analysis of the position of the energy peaks and their intensity information about the chemical composition and the amount of the pigments can be obtained. In this way position sensitive elemental analysis is possible.

The radiation hardness of CH3 NH3 PbI3 -based solar cells is evaluated from in situ measurements during high-energy proton irradiation. These organic-inorganic perovskites exhibit radiation hardness and withstand proton doses that exceed the damage threshold of crystalline silicon by almost 3 orders of magnitude. Moreover, after termination of the proton irradiation, a self-healing process of the solar cells commences.

In the following article a review is given on the use of accelerators in studies connected to our cultural heritage. It focuses on making use of the production and detection of x-rays as a general tool. At “small accelerators”, the proton induced x-ray emission (PIXE), especially when combined with Rutherford backscattering spectroscopy (RBS), has been developed to a very versatile and powerful technique for near-surface investigations. It is well complemented by larger facilities, synchrotron radiation sources as well as medium energy ion accelerators for high energy PIXE. With the development of small compact electron accelerators, a new generation of mono-energetic high-energy high-intensity x-ray sources will add a very comfortable complement in cultural heritage studies. To cite this article: H.-E. Mahnke et al., C. R. Physique 10 (2009).

Standard crystalline silicon homojunction solar cells have been irradiated with high energy protons at variable energies between 0.8 MeV and 65 MeV. As one possible criterion for the evaluation of the radiation induced degradation, we compared the suppression of the bandgap electroluminescence at a wavelength around 1150 nm for the solar cells, irradiated at different energies. The lowest electroluminescence efficiency has been observed for an intermediate proton energy of 1.7 MeV. At this energy value, however, crystalline silicon solar cells are not homogeneously damaged, as shown by the defect profiles, calculated by the SRIM code. We propose therefore a irradiation at a higher energy in order to obtain a relative homogeneous defect profile. At 65 MeV the projected range of the protons in silicon is about 2 cm and we obtain a nearly constant defect distribution in the solar cell and the irradiation can be performed in air. Subsequently we compared the fluence dependence of the degradation of the solar cell parameters after 65 MeV irradiation with other material parameters, such as effective diffusion lengths, as calculated by the quantum yield spectra and the effective excess charge carrier lifetime, as measured on silicon wafers by the contactless TRMC-technique. Similar degradation has been found for the short circuit current, solar cell efficiency and electroluminescence efficiency and a good agreement between diffusion length and excess charge carrier lifetime changes. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Naturwissenschaftler arbeiten mit Archaologen, Kunsthistorikern und Restauratoren zusammen, um Materialinformationen uber Kunstwerke und archaologische Artefakte gewinnbringend mit den Erkenntnissen aus Altertumsforschung, Kunstgeschichte und Denkmalpflege zu verbinden. Rontgenfluoreszenz und Rontgenemission sind die Methoden der Wahl, wenn wertvolle und fragile Objekte zerstorungsfrei zu untersuchen sind.

Die Eigenspannungen im Inneren eines mechanischen Bauteils sichtbar zu machen oder die verborgene innere Struktur eines Objekts auf den Mikrometer genau zu studieren, sind nur zwei Beispiele für den Einsatz zerstörungsfreier Messmethoden am Hahn-Meitner-Institut (HMI) in Berlin. An dieser Stelle sollen einige der wichtigsten davon sowie ihre Anwendungsfelder vorgestellt werden.

Naturwissenschaftliche Informationen, insbesondere die chemische Zusammensetzung der Objekte, können Hinweise auf die Hintergründe der Objektherstellung liefern, die der alleinigen kunsthistorischen Begutachtung verborgen blieben. Es können nicht nur Fragen nach dem Prozess, Zeitpunkt und Ort der Herstellung beantwortet werden. Die chemische Analyse gibt auch Hinweise auf Ereignisse und Veränderungen, die erst nach der Fertigstellung des Objektes erfolgten. So werden Alterungsphänomene oder historische Überarbeitungen und Restaurierungen aufgedeckt, aber auch Konservierungsstrategien zur Erhaltung der Kunstwerke unterstützt. Durch den technologischen Fortschritt im Bereich der röntgenanalytischen Methoden, die berührungsfrei, ohne Probennahme und ohne Schädigung für das Untersuchungsobjekt arbeiten, erschließen sich dem Analytiker erstmalig Möglichkeiten, auch sehr wertvolle und fragile Objekte zerstörungsfrei zu untersuchen.

Imaging methods with elemental contrast are of great value for the investigation of historical paintings, as they allow for study of sub-surface layers that provide insight into a painting's creation process. Two of the most important methods are neutron activation autoradiography (NAAR) and scanning macro-XRF (MA-XRF). Given the differences between these methods in the fundamental physical phenomena exploited, a theoretical comparison of their capabilities is difficult and until now a critical comparison of their use on the same painting is missing. In this paper, we present a study of Rembrandt van Rijn's painting Susanna and the Elders from the Gemaldegalerie in Berlin employing both techniques. The painting features a considerable number of overpainted features and a wide range of pigments with different elemental tracers, including earth pigments (Mn/Fe), Azurite (Cu), lead white (Pb), vermilion (Hg) and smalt (Co, As). MA-XRF can detect all elements above Si (Z = 14), suffers from few spectral overlaps and can be performed in a few tens of hours in situ, i.e. in a museum. NAAR requires the stay of the painting at a research facility for several weeks, and inter-element interferences can be difficult to resolve. Also, only a limited number of elements contribute to the acquired autoradiographs, most notably Mn, Cu, As, Co, Hg and P. However, NAAR provides a higher lateral resolution and is less hindered by absorption in covering layers, which makes it the only method capable of visualizing P in lower paint layers.

The feasibility has been investigated of using high-energy (68MeV) proton induced X-ray emission (PIXE) — a non-destructive analysis procedure — to identify the pigment composition, sequence and thickness of paint layers in various models prepared to simulate traditional painting techniques. Selected sites from the models were examined by traditional cross-section analysis in addition to high-energy PIXE in order to provide comparisons and illustrate the advantages and limitations of both procedures. A clear asset of the PIXE procedure, apart from its non-destructive nature, is the capacity to analyse many sites on an object in a rapid and efficient way. The limitations centre on the complications associated with distinguishing layer sequences containing more complex mixtures of pigments. Generally, therefore, high-energy PIXE is best used as a supplement — to cross-section analysis, for example — to gain additional information on painting technique and panel preparation.

In the present work we attempted to determine excitation energies and widths of proton unbound states in 32 Cl. These states may contribute as resonances to the 31 S(p,γ) reaction and will determine the reaction rate. Results were used to evaluate the reaction flow in the Si to Ar region obtained by nova outbursts in the case of an ONeMg white dwarf of 1.35 M ⊙ .

The therapy of eye tumors with fast protons is an excellent tool giving very high local control rates. At the Helmholtz-Zentrum Berlin (HZB) almost 1800 patients were treated since 1998. A 2 MV Tandetron™ was installed as injector for the k = 132 HZB cyclotron. Using the standard 358 duoplasmatron ion source with direct extraction of negative hydrogen ions an extremely stable proton beam can be delivered, both on the short-term and the long-term scale. The hair-needle filaments made from thoriated tungsten wires have safe operation times of more than 1000 h.

The applicability of amorphous silicon/crystalline silicon (a-Si:H/c-Si) heterojunction solar cells for their use in space environment was tested. The cells were subject to proton irradiation at energies between 0.8 and 4 MeV. The optical and electrical parameters were measured. The diffusion lengths, L-D(,) were deduced from the internal quantum efficiency. A plot of 1/L-D(2) vs the applied doses yielded the damage constant. This procedure was repeated for the energy range of 0.8-4 MeV. The damage constants were lower or comparable to those of diffused solar cells. As in the case of conventional solar cells a maximum was found for an energy of 1.7 MeV. The spectral response calculated by means of the AFORSHET simulation program was fitted to the experimental data, using an inhomogeneous defect distribution within the crystalline silicon substrate after irradiation. The defect density used as a fit parameter was proportional to the implanted proton dose. (c) 2006 The Electrochemical Society.