Technical manual: a survey of scintillating medium for high-energy particle detection

There are various particle detection methods used nowadays and the most common is using scintillators. Among scintillating materials, solid plastic and water-based liquid scintillators (WbLS) are the latest development. In particular, WbLS allows researchers to apply different particle detection methods for increased experiment efficiency. This survey attempts to make an overview on detection methods and detectors in high-energy physics using scintillators. It is meant as a summary for those new to scintillator detectors and looking for general material on the topic.Comment: UPDATED: This TM is a short summary meant as reference for those new to scintillators. This is an addition to other scintillator-related works published, and it is not meant to be published separately in a peer-reviewed journa

Bimeron nanoconfined design

We report on the stabilization of the topological bimeron excitations in confined geometries. The Monte Carlo simulations for a ferromagnet with a strong Dzyaloshinskii-Moriya interaction revealed the formation of a mixed skyrmion-bimeron phase. The vacancy grid created in the spin lattice drastically changes the picture of the topological excitations and allows one to choose between the formation of a pure bimeron and skyrmion lattice. We found that the rhombic plaquette provides a natural environment for stabilization of the bimeron excitations. Such a rhombic geometry can protect the topological state even in the absence of the magnetic field.Comment: 5 pages, 7 figure

Vertailu Barton-Bandis- ja Mohr-Coulomb-mallien käytöstä rakostabiliteetin analyysiin

For mining and civil engineering projects rock slope stability is an essential part of safety and financial considerations. While large-scale stability can be simulated using rock mass properties, at smaller scale local variations in rock properties become significant and failure purely along discontinuities is possible. Wedging and rockfall are common occurrences at this scale. These are often prevented by bolting or shotcrete support. For temporary slopes such support measures can be costly, and an ability to simulate possible failures along discontinuity planes becomes useful for evaluation of support necessity. Traditionally the Mohr-Coulomb failure model has been used. However, a model has been developed specifically for discontinuity shear strength analysis. This Barton-Bandis model is based on basic friction of rock and joint roughness. This study aims to compare the two models in practice both for accuracy and resources required. This is accomplished by carrying out a case study on the Siilinjärvi mine site rocks. Parameters for both models were collected with laboratory and in-situ tests. These included shear box, Schmidt hammer and tilt table tests as well as joint roughness profiling. The variability of these parameters was analysed and certain parameters were selected as the most appropriate for simulation. Several failure and non-failure cases were then simulated using these parameters to check their validity. Parameters were easier to obtain for the Barton-Bandis model. Additionally, the variation in Barton-Bandis predictions for each sample was considerably smaller than the variation for Mohr-Coulomb predictions, and using the average of Mohr-Coulomb parameters would create a dangerously overconfident estimation of strength. Barton-Bandis results were easier to interpret. Parameters selected for simulation were preliminarily shown to be valid. It was found that joint continuity is a decisive factor for simulation even at small scale, and that assuming continuous joints can create disproportionately conservative strength estimates.Kalliorakentamisen ja kaivosteollisuuden projekteissa kallioseinän stabiliteetti on olennainen osa rakennelman taloudellisuuden ja turvallisuuden tarkastelua. Suuren mittakaavan seinämästabiliteettia voidaan simuloida kivimassan ominaisuuksia hyödyntäen, kun taas pienemmällä mittakaavalla kiven ominaisuuksien paikallinen vaihtelu muuttuu ratkaisevaksi. Tällä mittakaavalla myös puhtaasti rakopintoja pitkin tapahtuvat sortumat ovat mahdollisia. Kiilasortumat ja kivien putoamiset ovat yleisiä ilmiöitä, jotka usein estetään pulttaamalla tai ruiskubetonoinnilla. Tilapäisien seinämien ja luiskien tapauksessa tällaiset tuentatoimet voivat olla kalliita, jolloin kyky simuloida rakopintoja pitkin tapahtuvia sortumia on hyödyksi tuentatarpeen arvioinnissa. Perinteisesti Mohr-Coulombin lujuusmallia on käytetty, mutta on kehitetty lujuusmalli myös nimenomaisesti raon leikkauslujuuden tarkasteluun. Tämä Barton-Bandis-malli perustuu kiven peruskitkaan sekä rakopinnan karkeuteen. Tutkimuksen tavoitteena on vertailla näiden mallien tarkkuutta sekä niihin tarvittavia resursseja käytännössä. Vertaus tehtiin tapaustutkimuksella Siilinjärven kaivoksella. Molempien lujuusmallien parametrit kerättiin laboratorio- ja kenttäkokeilla. Kokeisiin sisältyi leikkausrasiakoe, Schmidtin vasarakoe sekä kallistuspöytäkokeet ja rakopintojen profiloinnit. Näiden parametrien vaihtelua analysoitiin ja edustavat parametrit valittiin simulointiin. Joitakin sortuneita ja sortumattomia kohtia simuloitiin parametrien soveltuvuuden tarkistamiseksi. Parametrien hankinta oli helpompaa Barton-Bandis-mallille. Barton-Bandis-mallin näytekohtaisten lujuusennusteiden vaihtelu oli huomattavasti pienempää kuin Mohr-Coulomb-mallilla. Käyttämällä Mohr-Coulomb-mallin parametrien keskiarvoa saataisiin vaarallisen ylioptimistisia lujuusennusteita. Barton-Bandis-mallin tuloksia on näin ollen helpompi tulkita. Valittujen simulointiparametrien osoitettiin alustavasti olevan päteviä. Havaittiin, että rakojen jatkuvuus on ratkaiseva tekijä simuloinnissa myös pienessä mittakaavassa. Oletus rakojen täydellisestä jatkuvuudesta voi tuottaa suhteettoman konservatiivisia lujuusarvioita

Profile approach for recognition of three-dimensional magnetic structures

We propose an approach for low-dimensional visualisation and classification of complex topological magnetic structures formed in magnetic materials. Within the approach one converts a three-dimensional magnetic configuration to a vector containing the only components of the spins that are parallel to the z axis. The next crucial step is to sort the vector elements in ascending or descending order. Having visualized profiles of the sorted spin vectors one can distinguish configurations belonging to different phases even with the same total magnetization. For instance, spin spiral and paramagnetic states with zero total magnetic moment can be easily identified. Being combined with a simplest neural network our profile approach provides a very accurate phase classification for three-dimensional magnets characterized by complex multispiral states even in the critical areas close to phases transitions. By the example of the skyrmionic configurations we show that profile approach can be used to separate the states belonging to the same phase

VCSEL intrinsic response extraction using T-Matrix formalism

We present a new method to remove the parasitics contribution to the VCSEL chip response, in order to obtain the intrinsic S21 behavior. The on-chip VCSEL is defined as two cascaded two-port subsystems representing the electrical access and the VCSEL optical cavity respectively. S11 and S21 parameters measurements are carried-out using a probe station to characterize the chip response. An electrical equivalent circuit defining the behavior of the electrical access is combined with T-Matrix formalism to remove the parasitics contribution from the measured S21 response. Results allow us to determine the intrinsic 3-dB bandwidth of the VCSEL

Optimization of the Liquid Scintillator Composition

Nowadays, many particle detectors use liquid scintillator (LS) as a detection medium. In particular, Water-based Liquid Scintillator (WbLS) that is a new material currently under development. It is based on the idea of dissolving the organic scintillator in water using special surfactants. This material strives to achieve the novel detection techniques by combining the Cherenkov and scintillation light, as well as the total cost reduction compared to pure liquid scintillator. An important part of either the pure LS or WbLS production is to choose the right fluor and shifter and their concentrations. The choice affects the spectral distribution of the light output and the detection efficiency as each photodetector has its own spectral sensitivity region. This work presents the results of the study on the pseudocumen (PC) based LS with the PPO and POPOP/MSB as a fluor and shifters of choice. Both the total light yield and the spectral differences in the outputs with different amounts of components are shown. This study can be applied to plastic scintillators as well. 38t

Study of the resonance α+13C interaction at low energies: Optimization of parameters of the beam shape

About half of all elements heavier than iron are produced in a stellar environment through the s process, which involves a series of subsequent neutron captures and α decays. The reaction 13C(α,n)16O is considered to be the main source of neutrons for the s process at low temperatures in low mass stars in the asymptotic giant branch (AGB). In order to understand better creation of such elements we need to imrove the understanding of creation of such elements, that is to obtain the excitation functions of the 13C (α, α)17O elastic scattering at the initial beam energy 13C from 1.7Mev/A till energies close to zero by using the Thick Target Inverse Kinematics method (TTIK) [1]. The experiment will be conducted in Astana, KZ by using a new heavy ion accelerator DC-60 that provides ion beam with the energy 1.75 MeV/nucleon [1]. To improve the results and reduce errors, the profiling of the beam within the experimental camera is required. In this article, the detailed preparations for this measurement are described

Random Number Hardware Generator Using Geiger-Mode Avalanche Photo Detector

The main problems with existing hardware random number generators today are either low speed and/or prohibitively high cost. The physical concept and test results of sample data of the high-speed hardware true random number generator design based Hamamatsu MPPC photo sensor are shown. Main features of this concept are the high speed of the true random numbers generation (tens of Mbt/s), miniature size and estimated lower production cost. This allows the use of such a device not only in large companies and government offices but for the end-user data cryptography, in classrooms, in scientific Monte-Carlo simulations, computer games and any other place where large number of true random numbers is required. The physics of the operations principle of using a Geiger-mode avalanche photo detector is briefly discussed and the high quality of the data collected is demonstrated