Physikalisch-Technische Bundesanstalt Research Articles

P037] Implementation of a new free-air ionization chamber as a primary air kerma standard for mammography radiation qualities

Purpose The Physikalisch-Technische Bundesanstalt (PTB) offers air kerma calibrations of secondary standards for standard dosimetry laboratories worldwide. Due to the significant increase in the demand for such calibrations in mammography X-ray beams (tube high voltages ranging from 20 kV to 50 kV), it was decided to construct and manufacture a novel free-air ionization chamber (FAC) with a design especially optimized for radiation qualities used in mammography. This work describes the final technical construction of the new FAC and its implementation as a primary air kerma standard at PTB. Methods The new FAC is of the parallel-plate type optimized for the photon energy range of 5 keV to 50 keV. Special emphasis has been given to the design of a chamber without potential wires in the beamline to minimize the scattering and attenuation of the X-rays. The design of the chamber was optimized with respect to electrical field homogeneity using the software package SIMION Version 8.1. This software was also used to calculate k d , the correction factor for the distortion of the electric field of the final chamber design. The other correction factors for photon attenuation, scattering, aperture transmission and scattering, electron loss and violating charged-particle equilibrium have been calculated using the user code ’egs_fac’ of the EGSnrc Monte Carlo transport simulation software package. Finally, air kerma rates measured with the PK50, the new free-air chamber, were compared with those measured with the other well-established primary air kerma standards of PTB. Results The PK50 was fully characterized by all the necessary correction factors. The correction for the field distortion is below 0.8%, thus the design goal has been achieved. For the ISO narrow series, the correction factors calculated with egs_fac are below 1.0%, proving that the chamber is well optimized for energies below 50 keV. Comparisons of air kerma measurements with the PK50 and established FACs yielded results which were consistent within the uncertainties of a few parts in 1000. Conclusions The new chamber designated as the PK50 is now ready for use as a primary air kerma standard for low-energy X-rays at PTB.

Metrological Competence Center for Windenergy

The Competence Center for Windenergy of the Physikalisch-Technische Bundesanstalt provides a worldwide unique metrological infrastructure for high level calibrations of mechanical components for wind energy and wind lidar systems. The focus is on three measuring devices. First, a large coordinate measuring machine with a measuring volume of 5 m x 4 m x 2 m for drive train components, second, a wind tunnel for the calibration of mobile wind lidar systems, and third, a torque standard measuring machine for the calibration of torque transducers with a maximum load of 5·MN m, which can be expanded to 20 MN·m. The first part was completed with the inauguration of the Euler I building in February 2018. It functions as both, a large coordinate measuring machine and a wind tunnel. The standard torque measuring device is expected to be implemented in 2020 after finishing the Euler II building. The five-year project started in 2016. The cost of new buildings, measuring machines and developments is about 15 million €. The project is funded by the German Federal Ministry for Economic Affairs and Energy via the project’s executing organization in Jülich.

A novel automated diagnostic system for classification of myocardial infarction ECG signals using an optimal biorthogonal filter bank

Myocardial infarction (MI), also referred to as heart attack, occurs when there is an interruption of blood flow to parts of the heart, due to the acute rupture of atherosclerotic plaque, which leads to damage of heart muscle. The heart muscle damage produces changes in the recorded surface electrocardiogram (ECG). The identification of MI by visual inspection of the ECG requires expert interpretation, and is difficult as the ECG signal changes associated with MI can be short in duration and low in magnitude. Hence, errors in diagnosis can lead to delay the initiation of appropriate medical treatment. To lessen the burden on doctors, an automated ECG based system can be installed in hospitals to help identify MI changes on ECG. In the proposed study, we develop a single-channel single lead ECG based MI diagnostic system validated using noisy and clean datasets. The raw ECG signals are taken from the Physikalisch-Technische Bundesanstalt database. We design a novel two-band optimal biorthogonal filter bank (FB) for analysis of the ECG signals. We present a method to design a novel class of two-band optimal biorthogonal FB in which not only the product filter but the analysis lowpass filter is also a halfband filter. The filter design problem has been composed as a constrained convex optimization problem in which the objective function is a convex combination of multiple quadratic functions and the regularity and perfect reconstruction conditions are imposed in the form linear equalities. ECG signals are decomposed into six subbands (SBs) using the newly designed wavelet FB. Following to this, discriminating features namely, fuzzy entropy (FE), signal-fractal-dimensions (SFD), and renyi entropy (RE) are computed from all the six SBs. The features are fed to the k-nearest neighbor (KNN). The proposed system yields an accuracy of 99.62% for the noisy dataset and an accuracy of 99.74% for the clean dataset, using 10-fold cross validation (CV) technique. Our MI identification system is robust and highly accurate. It can thus be installed in clinics for detecting MI.

ECG-Based Personal Identification Using Empirical Mode Decomposition and Hilbert Transform

It is evident that biological signals of each subject (e.g., electrocardiogram signal) carry his/her unique signature; consequently, several attempts have been made to extract subject-dependent features from these signals with application to human verification. Despite numerous efforts to characterize electrocardiogram (ECG) signals and provide promising results for low population of subjects, the performance of state-of-the-art methods mostly fail in the presence of noise or arrhythmia. This paper presented an efficient and fast-to-compute ECG feature by applying empirical mode decomposition (EMD) to ECG signals, and then, instantaneous frequency, instantaneous phase, amplitude, and entropy features were extracted from the analytical form of the last EMD component. Finally, the k-nearest neighbor (kNN) classifier was utilized to classify the individuals’ features. The proposed method was compared to the conventional features such as fiducial points, correlation, wavelet coefficients, and principal component analysis (PCA). These methods were all applied to ECG signals of 34 healthy subjects derived from the Physikalisch-Technische Bundesanstalt (PTB) database. The results implied the effectiveness of the proposed method, providing 95% verification accuracy, which was not the best among the competitors but provided much lower dimensional feature space compared to the top-rank counterparts.

Generalized Lomb\u2013Scargle analysis of mathrm {^{90}Sr/^{90}Y} decay rate measurements from the Physikalisch\u2013Technische Bundesanstalt

We apply the generalized Lomb–Scargle (LS) periodogram to independently confirm the claim by Sturrock et al. (Astropart Phys 84:8. https://doi.org/10.1016/j.astropartphys.2016.07.005, 2016) of an oscillation at a frequency of 11/year in the decay rates of mathrm {^{90}Sr/^{90}Y} from measurements at the Physikalisch Technische Bundesanstalt (PTB), which however has been disputed by Kossert and Nahle (Astropart Phys 69:18. https://doi.org/10.1016/j.astropartphys.2015.03.003, 2015). For this analysis, we made two different ansatze for the errors. For each peak in the LS periodogram, we evaluate the statistical significance using non-parametric bootstrap resampling. We find using both of these error models evidence for 11/year periodicity in the mathrm {^{90}Sr/^{90}Y} data for two of the three samples, but at a lower significance than claimed by Sturrock et al. [1].

A large-area plate radiator with in situ temperature homogenization for thermographic imager calibration.

Large-area plate radiators with a high emissivity and uniform temperature distribution are needed as reference sources for calibrating infrared imagers and camera systems. However, achieving very uniform temperature distribution over a large area is technically challenging, especially at high temperatures. We present a large-area plate radiator with an improved uniformity in its surface temperature distribution for the calibration of infrared thermographic imagers. It is based on an industrial plate radiator which is temperature homogenized in situ by using the Data Reference Method (DRM) developed at the Physikalisch-Technische Bundesanstalt. The DRM takes three spatially shifted pictures of the plate radiator with a thermographic imager, and using this information, it calculates both the nonuniformity in the temperature distribution of the plate radiator and the nonuniformity in the response of the thermographic imager used for imaging the scene. The surface of the applied plate radiator is 300 mm × 300 mm and it operates in a temperature range from 30 °C to 600 °C. The surface is segmented into 9 different parts of identical size whose temperature can be individually controlled. The in situ controlled plate radiator system developed uses an infrared camera, whose detector is corrected for its response inhomogeneity using the DRM. This camera permanently monitors the plate radiator, and from these data, the temperature distribution of the plate is homogenized. Through this method, the homogeneity of the plate radiator can be considerably improved compared to the non-actively regulated mode of operation. For example, at a nominal temperature of 400 °C, without the in situ homogenization procedure, 90% of the plate area has a radiation temperature in the range from 391.7 °C to 403.6 °C. Applying the in situ homogenization procedure leads to 90% of the plate area having a radiation temperature in the range from 394.2 °C to 401.2 °C.

A new reference-type ionization chamber with direction-independent response for use in small-field photon-beam dosimetry – An experimental and Monte Carlo study

The frequently applied narrow and non-standard transverse dose profiles of intensity modulated photon-beam radiotherapy, lacking lateral secondary electron equilibrium, require the use of high-resolution dosimetry detectors, and small air-filled detectors are recommended as the reference detectors for cross-calibration of the high-resolution detectors. The present study focuses on the dosimetric properties of a novel cylindrical ionization chamber, the PTW Semiflex 3D 31021. The chamber's effective point of measurement was found to lie at (0.41±0.04) r downstream the tip of the inner surface of the spherical front wall in the axial orientation and (0.46±0.04) r upstream the chamber axis in the radial orientation. Due to its symmetrical design, the sigma values of its lateral dose response functions for all chamber's orientations are the same (2.10±0.05mm). The polarity correction factors obtained in this work do not exceed 0.1% and the saturation correction factor was below 1% up to a dose-per-pulse value of 0.956mGy. The radiation quality correction factor kQ of the chamber as a function of the tissue-phantom-ratio, TPR20,10, has been calculated by Monte Carlo simulation and has been determined experimentally at the German Metrology Institute (Physikalisch-Technische Bundesanstalt, PTB). The values of the non-reference condition correction factor kNR have been Monte-Carlo-calculated for use of the chamber at various depths and field sizes.

A soft X-ray cryogenic radiometer built on BSRF

In the field of the high injection rate X-ray meterage, currently there are no national standards in China, which are urgently needed in areas such as inertial confinement fusion diagnosis and aerospace observation. Globally, many metrology laboratories have developed their own meterage standards based on Cryogenic radiometers. And one soft X-ray cryogenic radiometer has been installed at 4B7B experiment station on Beijing Synchrotron Radiation Facility to measure the X-ray power from 50 nW to 1 $$\upmu \hbox {W}$$ . The purpose is to verify the accuracy of the X-ray power measurement and the performance of the cryogenic radiometer. The spectral responsivity of a Si photodiode detector calibrated in the Physikalisch-Technische Bundesanstalt of Germany is calibrated at 750 eV again with the cryogenic radiometer based on synchrotron light source. Some important performance parameters (e.g., time constant, responsivity, and nonequivalence error) of the cryogenic radiometer were measured and were in agreement with the design indexes. Calibration results show that total relative uncertainties of X-ray power measurement were below 1% ( $$k=1)$$ , and that good consistency was received compared with the calibrations done by the PTB. The cryogenic radiometer built at 4B7B is reliable and accurate for soft X-ray power measurement. And the performance of the cryogenic radiometer is also very good.

Determination of the active volumes of solid-state photon-beam dosimetry detectors using the PTB proton microbeam.

This study aims at the experimental determination of the diameters and thicknesses of the active volumes of solid-state photon-beam detectors for clinical dosimetry. The 10MeV proton microbeam of the PTB (Physikalisch-Technische Bundesanstalt, Braunschweig) was used to examine two synthetic diamond detectors, type microDiamond (PTW Freiburg, Germany), and the silicon detectors Diode E (PTW Freiburg, Germany) and Razor Diode (Iba Dosimetry, Germany). The knowledge of the dimensions of their active volumes is essential for their Monte Carlo simulation and their applications in small-field photon-beam dosimetry. The diameter of the active detector volume was determined from the detector current profile recorded by radially scanning the proton microbeam across the detector. The thickness of the active detector volume was determined from the detector's electrical current, the number of protons incident per time interval and their mean stopping power in the active volume. The mean energy of the protons entering this volume was assessed by comparing the measured and the simulated influence of the thickness of a stack of aluminum preabsorber foils on the detector signal. For all detector types investigated, the diameters measured for the active volume closely agreed with the manufacturers' data. For the silicon Diode E detector, the thickness determined for the active volume agreed with the manufacturer's data, while for the microDiamond detectors and the Razor Diode, the thicknesses measured slightly exceeded those stated by the manufacturers. The PTB microbeam facility was used to analyze the diameters and thicknesses of the active volumes of photon dosimetry detectors for the first time. A new method of determining the thickness values with an uncertainty of ±10% was applied. The results appear useful for further consolidating detailed geometrical knowledge of the solid-state detectors investigated, which are used in clinical small-field photon-beam dosimetry.

The Planck-Balance—using a fixed value of the Planck constant to calibrate E1/E2-weights

A balance is proposed, which allows the calibration of weights in a continuous range from 1 mg to 1 kg using a fixed value of the Planck constant, h. This so-called Planck-Balance (PB) uses the physical approach of Kibble balances that allow the Planck constant to be derived from the mass. Using the PB no calibrated mass standards are required during weighing processes any longer, because all measurements are traceable via the electrical quantities to the Planck constant, and to the meter and the second. This allows a new approach of balance types after the expected redefinition of the SI-units by the end of 2018. In contrast to many scientific oriented developments, the PB is focused on robust and daily use. Therefore, two balances will be developed, PB2 and PB1, which will allow relative measurement uncertainties comparable to the accuracies of class E2 and E1 weights, respectively, as specified in OIML R 111-1. The balances will be developed in a cooperation of the Physikalisch-Technische Bundesanstalt (PTB) and the Technische Universität Ilmenau in a project funded by the German Federal Ministry of Education and Research.

Calibration of high voltages at the ppm level by the difference of ^{83{mathrm{m}}}Kr conversion electron lines at the KATRIN experiment

The neutrino mass experiment KATRIN requires a stability of 3 ppm for the retarding potential at − 18.6 kV of the main spectrometer. To monitor the stability, two custom-made ultra-precise high-voltage dividers were developed and built in cooperation with the German national metrology institute Physikalisch-Technische Bundesanstalt (PTB). Until now, regular absolute calibration of the voltage dividers required bringing the equipment to the specialised metrology laboratory. Here we present a new method based on measuring the energy difference of two ^{83{mathrm{m}}}Kr conversion electron lines with the KATRIN setup, which was demonstrated during KATRIN’s commissioning measurements in July 2017. The measured scale factor M=1972.449(10) of the high-voltage divider K35 is in agreement with the last PTB calibration 4 years ago. This result demonstrates the utility of the calibration method, as well as the long-term stability of the voltage divider.

Traceable Measurements of Seebeck Coefficients of Thermoelectric Materials by Using Noble Metal Thermocouples

The characterization of thermoelectric materials as reference materials for Seebeck coefficients at the Physikalisch-Technische Bundesanstalt (PTB) is based on the usage of gold/platinum differential thermocouples. In the case of thermoelectric materials containing silicon, the gold/platinum thermocouples are insufficient due to reactions with the silicon when the samples are at higher temperatures. To overcome this limitation and to expand the temperature range for the certification process, platinum/palladium thermocouples were incorporated in the measurement setup. This paper discusses the influence of the different differential thermocouples used for the measurement of the Seebeck coefficients. Results of a comparative investigation of Seebeck coefficient measurements of a metallic and two semiconducting reference materials in the temperature range from 300 K to 870 K are presented.

Optical characterisation of three reference Dobsons in the ATMOZ Project – verification of G. M. B. Dobson's original specifications

Abstract. Three reference Dobsons (regional standard Dobsons No. 064, Germany and No. 074, Czech Republic as well as the world standard No. 083, USA) were optically characterized at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig in 2015 and at the Czech Metrology Institute (CMI) in Prague in 2016 within the EMRP ENV 059 project “Traceability for atmospheric total column ozone”. Slit functions and the related parameters of the instruments were measured and compared with G. M. B. Dobson's specifications in his handbook. All Dobsons show a predominantly good match of the slit functions and the peak (centroid) wavelengths with deviations between −0.11 and +0.12 nm and differences of the full width half maximum (FWHM) between 0.13 and 0.37 nm compared to the nominal values at the shorter wavelengths. Slightly larger deviations of the FWHMs from the nominal Dobson data, up to 1.22 nm, can be seen at the longer wavelengths, especially for the slit function of the long D-wavelength. However, differences between the effective absorption coefficients (EACs) for ozone derived using Dobson's nominal values of the optical parameters on one hand and these measured values on the other hand are not too large in the case of both “old” Bass–Paur (BP) and “new” IUP-ozone (Institut für Umweltphysik, University of Bremen) absorption cross sections. Their inclusion in the calculation of the total ozone column (TOC) leads to improvements of significantly less than ±1 % at the AD-wavelengths between −1 and −2 % at the CD-wavelengths pairs in the BP-scale. The effect on the TOC in the IUP-scale is somewhat larger at the AD-wavelengths, up to +1 % (D074), and smaller at the CD-wavelengths pair, from −0.44 to −1.5 %. Beside this positive effect gained from the data with higher metrological quality that is needed for trend analyses and satellite validation, it will be also possible to explain uncommon behaviours of field Dobsons during calibration services, especially when a newly developed transportable device TuPS (tuneable portable radiation source) from CMI proves its capability to provide similar results as the stationary setups in the laboratories of National Metrology Institutes. Then, the field Dobsons can be optically characterized as well during regular calibration campaigns. A corresponding publication will be prepared using the results of TuPS-based measurements of more than 10 Dobsons in field campaigns in 2017.

Analysis of Radiation-Induced Chromosomal Aberrations on a Cell-by-Cell Basis after Alpha-Particle Microbeam Irradiation: Experimental Data and Simulations.

There is a continued need for further clarification of various aspects of radiation-induced chromosomal aberration, including its correlation with radiation track structure. As part of the EMRP joint research project, Biologically Weighted Quantities in Radiotherapy (BioQuaRT), we performed experimental and theoretical analyses on chromosomal aberrations in Chinese hamster ovary cells (CHO-K1) exposed to α particles with final energies of 5.5 and 17.8 MeV (absorbed doses: ∼2.3 Gy and ∼1.9 Gy, respectively), which were generated by the microbeam at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany. In line with the differences in linear energy transfer (approximately 85 keV/μm for 5.5 MeV and 36 keV/μm for 17.8 MeV α particles), the 5.5 MeV α particles were more effective than the 17.8 MeV α particles, both in terms of the percentage of aberrant cells (57% vs. 33%) and aberration frequency. The yield of total aberrations increased by a factor of ∼2, although the increase in dicentrics plus centric rings was less pronounced than in acentric fragments. The experimental data were compared with Monte Carlo simulations based on the BIophysical ANalysis of Cell death and chromosomal Aberrations model (BIANCA). This comparison allowed interpretation of the results in terms of critical DNA damage [cluster lesions (CLs)]. More specifically, the higher aberration yields observed for the 5.5 MeV α particles were explained by taking into account that, although the nucleus was traversed by fewer particles (nominally, 11 vs. 25), each particle was much more effective (by a factor of ∼3) at inducing CLs. This led to an increased yield of CLs per cell (by a factor of ∼1.4), consistent with the increased yield of total aberrations observed in the experiments.

Diffuse near-infrared imaging of tissue with picosecond time resolution.

Optical imaging of biological tissue in vivo at multiple wavelengths in the near-infrared (NIR) spectral range can be achieved with picosecond time resolution at high sensitivity by time-correlated single photon counting. Measuring and analyzing the distribution of times of flight of photons randomly propagated through the tissue has been applied for diffuse optical imaging and spectroscopy, e.g. of human breast tissue and of the brain. In this article, we review the main features and the potential of NIR multispectral imaging with picosecond time resolution and illustrate them by exemplar applications in these fields. In particular, we discuss the experimental methods developed at the Physikalisch-Technische Bundesanstalt (PTB) to record optical mammograms and to quantify the absorption and scattering properties from which hemoglobin concentration and oxygen saturation of healthy and diseased breast tissue have been derived by combining picosecond time-domain and spectral information. Furthermore, optical images of functional brain activation were obtained by a non-contact scanning device exploiting the null source-detector separation approach which takes advantage of the picosecond time resolution as well. The recorded time traces of changes in the oxy- and deoxyhemoglobin concentrations during a motor stimulation investigation show a localized response from the brain.

Re-evaluation of the correction factors for the GROVEX

The GROVEX (GROssVolumige EXtrapolationskammer, large-volume extrapolation chamber) is the primary standard for the dosimetry of low-dose-rate interstitial brachytherapy at the Physikalisch-Technische Bundesanstalt (PTB). In the course of setup modifications and re-measuring of several dimensions, the correction factors have been re-evaluated in this work. The correction factors for scatter and attenuation have been recalculated using the Monte Carlo software package EGSnrc, and a new expression has been found for the divergence correction. The obtained results decrease the measured reference air kerma rate by approximately 0.9% for the representative example of a seed of type Bebig I25.S16C. This lies within the expanded uncertainty (k = 2).

Novel spectrometers for environmental dose rate monitoring

A new generation of dosemeters, based on the scintillators LaBr3, CeBr3 and SrI2, read out with conventional photomultipliers, to be used in the field of environmental gamma-radiation monitoring, was investigated. The main features of these new instruments and especially their outdoor performance, studied by long-term investigations under real weather conditions, are presented. The systems were tested at the reference sites for environmental radiation of the Physikalisch-Technische Bundesanstalt. The measurements are compared with that of well characterized classical dose rate reference instruments to demonstrate the suitability of new spectrometers for environmental dose rate monitoring even in adverse weather conditions. Their potential to replace the (mainly Geiger Müller based) dose rate meters operated in about 5000 European early waning network stations as well as in environmental radiation monitoring in general is shown.

Direct determination of kQ factors for cylindrical and plane-parallel ionization chambers in high-energy electron beams from 6 MeV to 20 MeV

For the ionometric determination of the absorbed dose to water, Dw, in high-energy electron beams from a clinical accelerator, beam quality dependent correction factors, kQ, are required. By using a water calorimeter, these factors can be determined experimentally and potentially with lower standard uncertainties than those of the calculated kQ factors, which are tabulated in various dosimetry protocols. However, one of the challenges of water calorimetry in electron beams is the small measurement depths in water, together with the steep dose gradients present especially at lower energies. In this investigation, water calorimetry was implemented in electron beams to determine kQ factors for different types of cylindrical and plane-parallel ionization chambers (NE2561, NE2571, FC65-G, TM34001) in 10 cm × 10 cm electron beams from 6 MeV to 20 MeV (corresponding beam quality index R50 ranging from 1.9 cm to 7.5 cm). The measurements were carried out using the linear accelerator facility of the Physikalisch-Technische Bundesanstalt. Relative standard uncertainties for the kQ factors between 0.50% for the 20 MeV beam and 0.75% for the 6 MeV beam were achieved. For electron energies above 8 MeV, general agreement was found between the relative electron energy dependencies of the kQ factors measured and those derived from the AAPM TG-51 protocol and recent Monte Carlo-based studies, as well as those from other experimental investigations. However, towards lower energies, discrepancies of up to 2.0% occurred for the kQ factors of the TM34001 and the NE2571 chamber.

COOMET Supplementary comparison L-S18 (project: 673/UA-a/15)

In 2016 this comparison was initialised to validate the CMC entries of the national metrology institutes (NMI) of Belarus, Ukraine and Russia. The German NMI, the Physikalisch-Technische Bundesanstalt (PTB), was identified as the pilot laboratory, responsible for planning, organizing and analysing the comparison. Moreover, the calibration values of PTB were used as reference values for this comparison because the PTB is the only participant in the presented comparison who has successfully participated in the latest international comparison on gears EURAMET.L-S24. All participants were asked to measure three different gear standards specialized for profile, helix and pitch measurements.The comparison was registered as the supplementary comparison COOMET.L-S18. The final report has been peer-reviewed and approved for publication by the CCL WG-MRA, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).KEY WORDS FOR SEARCHComparison measurement, gears, profile, helix, pitch, measurement uncertainty, CMC claimsMain textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Alpha-Induced Production Cross Sections of 77,79Kr and 77Br

The production cross sections of 77,79Kr and 77Br following the α-irradiation of natural selenium were determined between the α-energies of 11 MeV and 15 MeV using the activation technique. The irradiation of natural selenium targets with He2+ ions extracted from a cyclotron was conducted at Physikalisch-Technische Bundesanstalt in Braunschweig in Germany. The spectroscopic analysis of the reaction products was performed using a HPGe detector. As the α-beam was stopped inside the targets, the thick target yields were determined. The corresponding energy-dependent cross sections were calculated from the difference of the thick target yields at various beam energies. The determined values were compared to theoretical predictions based on the TALYS code.