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Scientific news from division 6

News 2020

As part of the EMPIR project “Remote and real-time optical detection of alpha-emitting radionuclides in the environment,” known as RemoteALPHA, a new detection system and a new metrological infrastructure are being developed that will use radioluminescence to optically detect alpha emitters in the environment. This project, which was launched on 1 September 2020 and is being coordinated by PTB,...

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Key innovations in the field of ultrashort pulse (USP) lasers have led to a growing number of USP laser machines being used in fields such as material processing. The legal regulations for radiation protection for such machines are currently under revision. The measurement results obtained within the scope of the authorization procedure of PTB’s USP laser machine also provide the data used as a...

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High-energy, pulsed reference radiation fields (energy: up to 20 MeV; pulse duration: a few microseconds) are currently being set up. This is taking place within the scope of a departmental research project (reference number: 3619S2236) funded by the BMU/BfS (Federal Ministry for the Environment, Nature Conservation and Nuclear Safety/Federal Office for Radiation Protection). Once the project has...

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Based on the long‑term experience and developments of Department 6.3 with regard to measuring very small currents of ionization chamber (in the range of a few 10‑15 amperes), a compact mobile measuring instrument was developed within the scope of a technical project. To this end, an innovative principle for measuring ionization currents and charges simultaneously was enhanced. In addition, modern...

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An ethernet‑to‑GPIB (IEEE‑488) data bus converter has been realized on the basis of the Raspberry Pi, a widely used, single‑board computer. Today, such converters are commercially available to a very limited extent only. However, they are required to secure the control of well‑established measuring systems with a GPIB in the long term via more modern interfaces (USB, ethernet). In addition, this...

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The Radiation Protection Dosimetry Department (6.3) is equipped with several reference measurement sites for ambient radiation dosimetry where ionizing radiation components in the environment are measured continuously. The measured values are monitored with regard to their consistency and plausibility. For this purpose, a data management platform was developed to allow data to be verified rapidly...

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Based on a multi‑leaf Faraday cup – developed specifically for PTB’s research electron accelerator – which is used to determine the energy of high‑energy electron radiation, a new, enhanced model has now been completed, calibrated and successfully tested. Compared to its predecessor, the new device has been optimized for the electron energies relevant to radiation therapy. In addition, it is...

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Since July 2019, Working Group 6.25 has been dealing with a project to develop a concept for the conversion of dose‑relevant parameters in computed tomography (CT) and cone‑beam computed tomography (CBCT). The dosimetry of these two methods is based on conceptually different quantities, which cannot be trivially standardized. These quantities are the dose length product (DLP) for CT and the dose...

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Accelerator, detector and accelerator tube from inside.

In radiation therapy, magnetic resonance imaging (MRI) is increasingly being used as an imaging procedure directly prior to and also during irradiation to guide the particle beam very precisely towards the tumorous tissue. But special corrections are necessary to characterize the particle beam under the influence of the magnetic field of MRI (dosimetry), since the detectors used for this purpose...

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In mammography, raw images are processed by means of sophisticated procedures before being used for diagnosis. According to the protocols that are presently valid, only raw images of technical phantoms are used for quality assurance in Europe today. In the medium term, however, it is planned to use anthropomorphic phantoms, that is to say, phantoms that have realistic anatomic structures. To be...

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The distribution of the neutron background in the experimental area of the iThemba neutron beam was calibrated with IRSN’s Bonner sphere spectrometer and compared with particle track simulations to identify weak points in the target shielding. Based on the results obtained, improved shielding was designed and...

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The newly developed radiation pulse measuring system is equipped with just one detector but is capable of measuring radiation pulses across a broad range of pulse durations and intensities. It is able to plot intensity and dose rates with a time resolution of a few ns and allows dose rate measurements ranging from just a few mGy/h in continuous radiation fields to several MGy/h in pulsed fields.

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Reference dosimetry performed with calibrated ionization chambers in carbon beams has a significantly higher measurement uncertainty than that in high-energy photon fields. This is mainly attributable to the relatively high uncertainty of the correction factor for the radiation quality kQ, which must be theoretically calculated in carbon beams because no experimental data are available.

kQ...

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The IAEA TRS-398 code of practice for dose measurement in external radiation therapy is currently being revised with the active participation of scientists from Department 6.2 of PTB. The main objectives of this revision are to take the ICRU’s latest recommendations on fundamental dosimetric constants into...

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The fundamental dose quantity for low‑energy X‑ray therapy is the absorbed dose to water at the surface of a water phantom. The unit of this quantity is disseminated via a coplanar ionization chamber that is flush‑mounted inside a PMMA phantom. This ionization chamber is directly calibrated using a quantity referred to as the “absorbed dose to...

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For the development at Division 4 of a new generation of optical atomic clocks with even lower uncertainties, a source of Th‑229 atoms is needed. One way to produce Th‑229 atoms is to obtain them as recoil ions from the alpha decay of U‑233. An initial analysis of a source produced at the Institute of Nuclear Chemistry of Johannes Gutenberg University Mainz was carried out using defined solid...

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For the low activity range, conventional standards (consisting of gaseous Rn‑222) are not suited to the realization and dissemination of the Bq/m³ unit with respect to Rn‑222. An alternative is found in Ra‑226 sources whose physicochemical properties are such that a certain fraction of the direct progeny, Rn‑222, emanates from the source. New statistical methods based on the Bayesian filters...

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Within the scope of the traceRadon project, radon detectors are being developed that can traceably measure the radon activity concentration in outdoor air. Such measurements are necessary to enable the use of the radon tracer method (RTM) in establishing a correlation with greenhouse gases (EMPIR 19ENV01 traceRadon). Calibrations will be made possible by combining the source directly with an...

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As part of the digitalization of the metrology sector, efforts are underway to apply artificial intelligence methods in the field of spectrometry. Convolutional neural networks (CNNs), for example, are being tested for use in nuclide identification and, in combination with Monte Carlo simulation, in the deconvolution of spectra.

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A new method to determine the activity of actinium–225 has been developed at PTB. This novel method is based on liquid scintillation counting. The activity concentration of a corresponding solution was determined with a relative uncertainty of only 0.16 %. Furthermore, the half–lives of actinium–225 and polonium–213 were measured extremely accurately.

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