No Arabic abstract
The microwave resonator is one of the key components in the modern Electron Paramagnetic Resonance (EPR) spectroscopy setup, as it largely determines the performance characteristics and limitations of the entire spectrometer. In this research note the possible way of resonator optimization is described. A detailed computer model describing the distribution of the electromagnetic field for Bruker 4118X-MD-5W1 design resonator has been developed. All details including a dielectric insert, conductive screen, coupling antenna and PTFE supports were included in the model. All dissipation processes were considered in the calculation. The influence of the resonator geometry on the Q-factor, filling factor and operating frequency of the resonant mode has been investigated. The resonator geometric parameters are optimized to achieve maximum sensitivity. According to the calculations, the optimized resonator structure has in 10 times greater sensitivity than the original MD-5 design.
This note presents a method to tune the resonant frequency $f_{0}$ of a rectangular microwave cavity. This is achieved using a liquid metal, GaInSn, to decrease the volume of the cavity. It is possible to shift $f_{0}$ by filling the cavity with this alloy, in order to reduce the relative distance between the internal walls. The resulting modes have resonant frequencies in the range $7div8,$GHz. The capability of the system of producing an Electron Paramagnetic Resonance (EPR) measurement has been tested by placing a 1 mm diameter Yttrium Iron Garnet (YIG) sphere inside the cavity, and producing a strong coupling between the cavity resonance and Kittel mode. This work shows the possibility to tune a resonant system in the GHz range, which can be useful for several applications.
The wide application of the modern resonant measurement techniques makes all the steps of the measuring process, including data acquisition more efficient and reliable. Here we investigate the multidimensional space of the parameters to determine the optimum span for resonant measurements. The study concentrated on experimental systems with standard performance and capabilities. We determine the range of the optimum span for the resonant frequency and quality factor by simulating and fitting resonant curves with different levels of asymmetry.
The Jagiellonian-PET (J-PET) collaboration is developing a prototype TOF-PET detector based on long polymer scintillators. This novel approach exploits the excellent time properties of the plastic scintillators, which permit very precise time measurements. The very fast, FPGA-based front-end electronics and the data acquisition system, as well as, low- and high-level reconstruction algorithms were specially developed to be used with the J-PET scanner. The TOF-PET data processing and reconstruction are time and resource demanding operations, especially in case of a large acceptance detector, which works in triggerless data acquisition mode. In this article, we discuss the parallel computing methods applied to optimize the data processing for the J-PET detector. We begin with general concepts of parallel computing and then we discuss several applications of those techniques in the J-PET data processing.
Ultracold neutrons (UCN) with kinetic energies up to 300 neV can be stored in material or magnetic confinements for hundreds of seconds. This makes them a very useful tool for probing fundamental symmetries of nature, by searching for charge-parity violation by a neutron electric dipole moment, and yielding important parameters for Big Bang nucleosynthesis, e.g. in neutron-lifetime measurements. Further increasing the intensity of UCN sources is crucial for next-generation experiments. Advanced Monte Carlo (MC) simulation codes are important in optimization of neutron optics of UCN sources and of experiments, but also in estimation of systematic effects, and in bench-marking of analysis codes. Here we will give a short overview of recent MC simulation activities in this field.
We conduct a comprehensive set of tests of performance of surface coils used for nuclear magnetic resonance (NMR) study of quasi 2-dimensional samples. We report ${^{115} rm{In}}$ and ${^{31} rm{P}}$ NMR measurements on InP, semi-conducting thin substrate samples. Surface coils of both zig-zag meander-line and concentric spiral geometries were used. We compare reception sensitivity and signal-to-noise ratio (SNR) of NMR signal obtained by using surface-type coils to that obtained by standard solenoid-type coils. As expected, we find that surface-type coils provide better sensitivity for NMR study of thin films samples. Moreover, we compare the reception sensitivity of different types of the surface coils. We identify the optimal geometry of the surface coils for a given application and/or direction of the applied magnetic field.