Detekcja molekuł metastabilnych He2∗He_{2}* w plazmie helowej

Metastable He2* molecules, ubiquitous in helium systems, consist of a metastable He* (2^3S1) and a ground-state He atoms. Their detection through the optical transition a^3Σu^+(ν=0) has been performed in He plasma (P=8-267 mbar) with a tunable cw laser at 465 nm, based on the sum frequency generation of 923 and 937 nm in the PP-KTP crystal. The laser has been characterized for its wavelength tuning and efficiency of nonlinear conversion. Absorption rates provide direct access to He2* number densities, based on quantitative spectroscopic data obtained for the probed rotational branches. Studies mainly involve 3He2* but its isotopologues are also studied in isotopic mixtures and pure 4He gas. He2*absorption spectra yield rotational temperatures close to the gas temperatures. In addition to the spin-statistics-driven line intensities alternation, an alternation of 3He2* line shapes occurs indicative of the underlying structure of the rotational states. Time evolution of absorption signals has been recorded in discharge afterglow providing quantitative information about dynamics and relative abundances of the metastable species. The He∗ density varies for strong laser excitation of He* at 1083 nm, as formation rate from the 23P state is 100-times higher. Simultaneous absorption measurements on atoms and molecules during the metastability exchange optical pumping (MEOP) experiments has been performed to study the potential contribution of He2* to the laser-enhanced 3He nuclear relaxation observed in MEOP. Preliminary results have shown expected increase in molecular density that is so far mild in comparison with the spectacular enhancement of 3He nuclear relaxation rate

Possibility of measurement of cross section and vector analyzing powers of p−^{3}He scattering at the Bronowice Cyclotron Center

A new possibility of continuation of few-nucleon dynamics studies at medium energies has appeared together with a new facility at the Institute of Nuclear Physics PAN in Kraków — The Bronowice Cyclotron Center (CCB). The new cyclotron PROTEUS provides a proton beam in an energy range of 70–230 MeV. Current progress in the theoretical calculations for four-nucleon (4N) systems is a main motivation to investigate p−^{3}He scattering. Due to the fact that the beam cannot be polarized, the only possibility to study spin observables is to build a polarized ^{3}He target system. A planned experiment assumes the construction of a cylindrical double Pyrex cell with separated pumping and target chambers with an additional polyamide film covering apertures for the passing beam and the reaction products. To polarize ^{3}He gas, the spin-exchange optical pumping method will be used

A novel system for patient ventilation and dosing of hyperpolarized ^{3}He for magnetic resonance imaging of human lungs

A versatile ventilator for controlling a patient’s breath cycle and dosing 3He gas has been designed and constructed. It is compatible with a medical magnetic resonance imaging scanner and can be incorporated into routine human lungs imaging procedure that employs hyperpolarized noble gas as a contrast agent. The system adapts to the patient’s lung volume and their breath cycle rhythm, providing maximum achievable comfort during the medical examination. Good quality magnetic resonance lung images of healthy volunteers were obtained. The system has the capability of recycling the exhaled gas to recover the expensive 3He isotope, and can be also adapted to human lung imaging with hyperpolarized 129Xe

Analysis procedure of the positronium lifetime spectra for the J-PET detector

Positron Annihilation Lifetime Spectroscopy (PALS) has shown to be a powerful tool to study the nanostructures of porous materials. Positron Emissions Tomography (PET) are devices allowing imaging of metabolic processes e.g. in human bodies. A newly developed device, the J-PET (Jagiellonian PET), will allow PALS in addition to imaging, thus combining both analyses providing new methods for physics and medicine. In this contribution we present a computer program that is compatible with the J-PET software. We compare its performance with the standard program LT 9.0 by using PALS data from hexane measurements at different temperatures. Our program is based on an iterative procedure, and our fits prove that it performs as good as LT 9.0.Comment: 4 figures, 8 page

Overview of the software architecture and data flow for the J-PET tomography device

Modern TOF-PET scanner systems require high-speed computing resources for efficient data processing, monitoring and image reconstruction. In this article, we present the data flow and software architecture for the novel TOF-PET scanner developed by the J-PET Collaboration. We discuss the data acquisition system, reconstruction framework and image reconstruction software. Also, the concept of computing outside hospitals in the remote centers such as Świerk Computing Centre in Poland is presented

Sampling FEE and trigger-less DAQ for the J-PET scanner

In this paper, we present a complete Data Acquisition System (DAQ) together with the readout mechanisms for the J-PET tomography scanner. In general, detector readout chain is constructed out of Front-End Electronics (FEE) measurement devices such as Time-to-Digital or Analog-to-Digital Converters (TDCs or ADCs), data collectors and storage. We have developed a system capable for maintaining continuous readout of digitized data without preliminary selection. Such operation mode results in up to 8 Gbps data stream, therefore, it is required to introduce a dedicated module for on-line event building and feature extraction. The Central Controller Module, equipped with Xilinx Zynq SoC and 16 optical transceivers, serves as such true real time computing facility. Our solution for the continuous data recording (trigger-less) is a novel approach in such detector systems and assures that most of the information is preserved on the storage for further, high-level processing. Signal discrimination applies a unique method of using LVDS buffers located in the FPGA fabric

A method to produce linearly polarized positrons and positronium atoms with the J-PET detector

A method for creating linearly polarized positrons and ortho-positronium (o-Ps) atoms with the J-PET detector is presented. The unique geometry and properties of the J-PET tomography enable one to design a positron source such that the quantization axis for the estimation of the linear polarization of produced o-Ps can be determined on the event by event basis in a direction of the positron motion. We intend to use ²²Na or other β⁺ decay isotopes as a source of polarized positrons. Due to the parity violation in the beta decay, the emitted positrons are longitudinally polarized. The choice of the quantization axis is based on the known position of the positron emitter and the reconstructed position of the positronium annihilation. We show that the J-PET tomography is equipped with all needed components

Introduction of total variation regularization into filtered backprojection algorithm

In this paper we extend the state-of-the-art filtered backprojection (FBP) method with application of the concept of Total Variation regularization. We compare the performance of the new algorithm with the most common form of regularizing in the FBP image reconstruction via apodizing functions. The methods are validated in terms of cross-correlation coefficient between reconstructed and real image of radioactive tracer distribution using standard Derenzo-type phantom. We demonstrate that the proposed approach results in higher cross-correlation values with respect to the standard FBP method

Time calibration of the J-PET detector

The Jagiellonian Positron Emission Tomograph (J-PET) project carried out in the Institute of Physics of the Jagiellonian University is focused on construction and tests of the first prototype of PET scanner for medical diagnostic which allows for the simultaneous 3D imaging of the whole human body using organic scintillators. The J-PET prototype consists of 192 scintillator strips forming three cylindrical layers which are optimized for the detection of photons from the electron-positron annihilation with high time- and high angular-resolutions. In this article we present time calibration and synchronization of the whole J-PET detection system by irradiating each single detection module with a 22Na source and a small detector providing common reference time for synchronization of all the modules