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

Learning partial differential equations from data

Partial differential equations (PDEs) are ubiquitous in science and engineering for their ability to model the behavior of various systems. In science, PDEs are used to model a multitude of phenomena ranging from quantum mechanics to brain modeling. In engineering, PDEs form the basis of most simulation software which is used to model processes such as heat transfer and collapse of structures. Many systems of interest already have accurate PDE-based models, but some systems are so complex that describing them in terms of PDEs possesses a serious challenge. This process might be simplified with the help of machine learning. When there is enough observations about a system, PDEs governing this system might be "learned". This work proposes a method of learning black-box approximations of PDEs from data. The method is based on graph neural networks which allows it to be used on unstructured spatial grids. Furthermore, the continuous-time nature of the method makes it robust against perturbations in the time grid. Experiments demonstrate that the method can be applied to different types of PDEs, can be used on solution domains of different shapes, supports different boundary conditions and is able to work with noisy data

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

Insecticidal contact toxicity of several essential oils against stored product pests: Poster

Results of laboratory bioassays in Petri dishes on evaluation of contact toxicity of Illicium verum, Artemisia absinthium and Abies sibirica essential oils (EOs) against larvae of khapra beetle, Trogoderma granarium Ev., adults of grain weevil, Sitophilus granarius L., and rice weevil, Sitophilus oryzae L., and confused flour beetle, Tribolium confusum Duv., and larvae and adults of the lesser mealworm, Tenebrio molitor L., are presented. EOs commercial samples from retail pharmacy were tested at doses 0.01, 0.25, 0.50, 0.75 and 1.00 µl/cm2. A treated Petri dish surface treted with acetone was used as a control. The experiment was carried out in triplicate. Mortality of insects was assessed after 1, 3, 6 and 24 hours post exposure. After exposure insects were placed into untreated Petri dishes for 3 days. The main components of the A. absinthium EOs are thujil alcohol (19.65%), phellandrene (16.71%), borneol (12.1%) and thujone (11.55%) was found. The major component of I. verum EOs was anethole (98.64%). Isobornyl acetate (57.25%), a-pinene (13.55%) and limonene (10.62%) were found as the main components of A. sibirica EOs. S. oryzae and S. granarius were most sensitive to each EO. I. verum EOs was the most effective and caused 100% mortality of each insect at the dose 0.25 µl/cm2.Results of laboratory bioassays in Petri dishes on evaluation of contact toxicity of Illicium verum, Artemisia absinthium and Abies sibirica essential oils (EOs) against larvae of khapra beetle, Trogoderma granarium Ev., adults of grain weevil, Sitophilus granarius L., and rice weevil, Sitophilus oryzae L., and confused flour beetle, Tribolium confusum Duv., and larvae and adults of the lesser mealworm, Tenebrio molitor L., are presented. EOs commercial samples from retail pharmacy were tested at doses 0.01, 0.25, 0.50, 0.75 and 1.00 µl/cm2. A treated Petri dish surface treted with acetone was used as a control. The experiment was carried out in triplicate. Mortality of insects was assessed after 1, 3, 6 and 24 hours post exposure. After exposure insects were placed into untreated Petri dishes for 3 days. The main components of the A. absinthium EOs are thujil alcohol (19.65%), phellandrene (16.71%), borneol (12.1%) and thujone (11.55%) was found. The major component of I. verum EOs was anethole (98.64%). Isobornyl acetate (57.25%), a-pinene (13.55%) and limonene (10.62%) were found as the main components of A. sibirica EOs. S. oryzae and S. granarius were most sensitive to each EO. I. verum EOs was the most effective and caused 100% mortality of each insect at the dose 0.25 µl/cm2