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AbstractA method of the determination of a γ-quantum absorption point in a plastic scintillator block using a matrix of wavelength-shifting (WLS) strips is proposed. An application of this method for the improvement of position resolution in newly proposed positron emission tomography (PET) detectors based on plastic scintillators is presented. The method enables to reduce parallax errors in the reconstruction of images, which occurs in the presently used PET scanners.

AbstractThis paper describes three methods regarding the production of plastic scintillators. One method appears to be suitable for the manufacturing of plastic scintillators, revealing properties which fulfill the requirements of novel positron emission tomography scanners based on plastic scintillators. The key parameters of the manufacturing process are determined and discussed.

AbstractThis article is focused on data acquisition system (DAQ) designed especially to be used in positron emission tomography (PET) or single-photon emission computed tomography. The system allows for continuous registration of analog signals during measurement. It has been designed to optimize registration and processing of the information carried by signals from the detector system in PET scanner. The processing does not require any rejection of data with a trigger system. The proposed system possesses also an ability to implement various data analysis algorithms that can be performed in real time during data collection.

AbstractPhotomultipliers are commonly used in commercial PET scanner as devices that convert light produced in scintillator by gamma quanta from positron-electron annihilation into electrical signal. For proper analysis of obtained electrical signal, a photomultiplier gain curve must be known, since gain can be significantly different even between photomultipliers of the same model. In this article, we describe single photoelectron method used for photomultiplier calibration applied for J-PET scanner, a novel PET detector being developed at Jagiellonian University. A description of calibration method, an example of calibration curve, and a gain of few Hamamatsu R4998 photomultipliers are presented.

AbstractUsing a theory of list-mode maximum likelihood expectation-maximization (MLEM) algorithm, in this contribution, we present a derivation of the system response kernel for a novel positron emission tomography (PET) detector based on plastic scintillators.

AbstractNovel time-of-flight positron emission tomography (TOF-PET) scanner solutions demand, apart from the state-of-the-art detectors, software for fast processing of the gathered data, monitoring of the whole scanner, and reconstruction of the PET image. In this article, we present an analysis framework for the novel STRIP-PET scanner developed by the J-PET collaboration in the Institute of Physics of the Jagiellonian University. This software is based on the ROOT package used in many particle physics experiments.

AbstractA positron emission tomography (PET) scan does not measure an image directly. Instead, a PET scan measures a sinogram at the boundary of the field-of-view that consists of measurements of the sums of all the counts along the lines connecting the two detectors. Because there is a multitude of detectors built in a typical PET structure, there are many possible detector pairs that pertain to the measurement. The problem is how to turn this measurement into an image (this is called imaging). Significant improvement in PET image quality was achieved with the introduction of iterative reconstruction techniques. This was realized approximately 20 years ago (with the advent of new powerful computing processors). However, three-dimensional imaging still remains a challenge. The purpose of the image reconstruction algorithm is to process this imperfect count data for a large number (many millions) of lines of response and millions of detected photons to produce an image showing the distribution of the labeled molecules in space.

AbstractAll of the present methods for calibration and monitoring of time-of-flight positron emission tomography (TOF-PET) scanner detectors utilize radioactive isotopes, such as 22Na or 68Ge, which are placed or rotate inside the scanner. In this article, we describe a novel method based on the cosmic rays application to the PET calibration and monitoring methods. The concept allows to overcome many of the drawbacks of the present methods and it is well suited for newly developed TOF-PET scanners with a large longitudinal field of view. The method enables also the monitoring of the quality of the scintillator materials and in general allows for the continuous quality assurance of the PET detector performance.

AbstractThis article presents an application of a novel technique for precise measurements of time and charge based solely on a field programmable gate array (FPGA) device for positron emission tomography (PET). The described approach simplifies electronic circuits, reduces the power consumption, lowers costs, merges front-end electronics with digital electronics, and also makes more compact final design. Furthermore, it allows to measure time when analog signals cross a reference voltage at different threshold levels with a very high precision of ~15 ps (rms) and thus enables sampling of signals in a voltage domain.

In tribology, a way of improving efficiently the understanding of the mechanical/thermal/environmental interactions on the chemical reactivity at the surface and interface level is to perform experiments where contact conditions are perfectly controlled (in terms of partial oxygen pressure, moisture or vacuum, and temperature). For this reason, an environmental tribometer was developed. The aim of this article is to set out the chosen technological solutions, to present the instrumentation (force, displacement, pressure temperature and contact resistance sensors, in situ gas analyser), and to describe the performances of this protoype. En tribologie, un moyen de progresser efficacement dans la compr?hension des ph?nom?nes de couplage m?canique/thermique/environnemental sur la r?activit? au niveau des surfaces et des interfaces est l'exp?rimentation o? les conditions de contact sont parfaitement contr?l?es (en termes de pression partielle d'oxyg?ne, d'humidit? ou sous vide, et de temp?rature). Pour cela, un tribom?tre environnemental a ?t? d?velopp?. L'objet de cet article est d'exposer les solutions technologiques adopt?es, de pr?senter l'instrumentation (capteurs de force, de d?placement, de pression, de temp?rature, de r?sistance de contact, analyseur de gaz in?situ), et de d?crire les performances de ce prototype.

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• A semi-analytical method is proposed to the 3D pattern recognition of particle traces. • Particles move on straight line in absence of magnetic field and on helix inside. • The efficiency for events with 5 tracks is above 91% for higher energy, 79% for 0.55 GeV/c. In this study, we present an algorithm for 3D track finding in the Forward Tracker of the PANDA experiment. This tracker is based on straw tube detectors and is designed to measure the deflection of particles in the magnetic field of the PANDA dipole magnet in order to determine their momenta. The algorithm uses the track road method for selecting track candidates. The applied track model in the projection onto the bending plane in the region before, inside and after the dipole magnet gap consists of line, circle and line, respectively. In the non-bending plane, a track projection is represented by a straight line. The algorithm was tested using simulated tracks of muons and obtained results for the track finding efficiency and for the momentum resolution are presented. [ABSTRACT FROM AUTHOR]

A compact detection system for heavy ions scattered in collisions at the Coulomb barrier is presented. This system, consisting of four identical, low-pressure Parallel Plate Avalanche Counter (PPAC) modules with two sensitive layers each, was built to operate in an ultra-high-vacuum environment inside the EPoS II solenoid spectrometer at GSI Darmstadt. The detector covers polar angles between 20° and 70° with respect to the beam axis, and about 80% of 2π in azimuthal angle. Segmented cathodes and a delay-line read-out allow for a determination of both angles with a precision of δΘ≈0.7° in polar and δΦ≈1.5° in azimuthal angle, respectively. The system has been proven to be capable of handling instantaneous rates of up to 5×105detected ions per second per module. It neither exhibits the degradation of detection efficiency nor loss in resolution over a 500 h period of a 6 MeV/u238U+181Tameasurement at average luminosities of 8×1027cm−2s−1.

E0-enhanced spectra of conversion electrons taken after (α,α′) and (α,2n) reactions and after projectile Coulomb excitation improve our knowledge about first and second excited bands in 238U and 240Pu built on 02+and 03+states which lie anomalously close together. The two bands are of different structure.