Photon HBT interferometry for non-central heavy-ion collisions

Currently, the only known way to obtain experimental information about the space-time structure of a heavy-ion collision is through 2-particle momentum correlations. Azimuthally sensitive HBT interferometry (Hanbury Brown-Twiss intensity interferometry) can complement elliptic flow measurements by constraining the spatial deformation of the source and its time evolution. Performing these measurements on photons allows us to access the fireball evolution at earlier times than with hadrons. Using ideal hydrodynamics to model the space-time evolution of the collision fireball, we explore theoretically various aspects of 2-photon intensity interferometry with transverse momenta up to 2 GeV, in particular the azimuthal angle dependence of the HBT radii in non-central collisions. We highlight the dual nature of thermal photon emission, in both central and non-central collisions, resulting from the superposition of QGP and hadron resonance gas photon production. This signature is present in both the thermal photon source function and the HBT radii extracted from Gaussian fits of the 2-photon correlation function.Comment: 18 pages, 12 figure

Lag time determination in DEC measurements with PTR-MS

The disjunct eddy covariance (DEC) method has emerged as a popular technique for micrometeorological flux measurements of volatile organic compounds (VOCs). It has usually been combined with proton transfer reaction mass spectrometry (PTR-MS), an online technique for VOC concentration measurements. However, the determination of the lag time between wind and concentration measurements has remained an important challenge. To address this issue, we studied the effect of different lag time methods on DEC fluxes. The analysis was based on both actual DEC measurements with PTR-MS and simulated DEC data derived from high frequency H<sub>2</sub>O measurements with an infrared gas analyzer. Conventional eddy covariance fluxes of H<sub>2</sub>O served as a reference in the DEC simulation. The individual flux measurements with PTR-MS were rather sensitive to the lag time methods, but typically this effect averaged out when the median fluxes were considered. The DEC simulation revealed that the maximum covariance method was prone to overestimation of the absolute values of fluxes. The constant lag time methods, one based on a value calculated from the sampling flow and the sampling line dimensions and the other on a typical daytime value, had a tendency to underestimate. The visual assessment method and our new averaging approach utilizing running averaged covariance functions did not yield statistically significant errors and thus fared better than the habitual choice, the maximum covariance method. Given this feature and the potential for automatic flux calculation, we recommend using the averaging approach in DEC measurements with PTR-MS. It also seems well suited to conventional eddy covariance applications when measuring fluxes near the detection limit

Hienomurskaamon laaja käytettävyyden tarkastelu

Tiivistelmä. Terrafame Oy:llä on ollut vuosien saatossa haasteita malmin murskaimien pinnanmittauksen kanssa ja tämä on luonut tähän päivään mielikuvan mittauksen epäluotettavuudesta. Tässä diplomityössä oli tarkoitus selvittää pinnanmittauksen tämän hetkinen luotettavuus, esiintuoda haasteet, joita mittauksessa on sekä selvittää syyt pinnan voimakkaaseen ja nopeaan vaihteluun. Lisäksi työssä tarkastellaan murskaimien lämpötilanmittauksia sekä murskaimien aputoimintojen käytettävyyttä. Työ tehtiin toimeksiantona Terrafame Oy:lle 1.2.2019–31.7.2019 välisenä aikana. Kirjallisuudessa on käyty läpi tilastollisen analyysin ja käytettävyyden laskennan perusteet, sekä tyypilliset vikadiagnostiikan keinot. Diplomityö toteutettiin tilastollisena tutkimuksena käyttäen data-analyysissa murskaamon mittaushistoriaa, materiaalikulutusten historiaa sekä asiantuntijahaastatteluja. Murskaimien pinnanmittauksen luotettavuuden tarkastelua varten asennettiin varmentava malminpinnanmittaus murskaimeen 342MRK0008. Tutkimuksen aikana kyettiin parantamaan pinnanmittauksien luotettavuutta toteuttamalla tutkille päivitykset, joilla mahdollistettiin laitevalmistajan uusimpien teknologioiden käyttö murskaamolla. Tämän lisäksi pintatutkille toimitettiin kolme työohjetta. Murskaimen huippulaakerin lämpötilamittauksen tarkastelussa havaittiin virhettä, joka poistettiin. Tutkimuksessa tarkasteltiin murskaimien tukitoiminnoista huippulaakerin rasvausjärjestelmää, sähköistä paineventtiiliä sekä puhdistavaa paineilmaa. Huippulaakerin rasvausjärjestelmästä ja sähköisestä paineventtiilistä toimitettiin Terrafamelle tekniset selvitykset. Tutkimuksessa tehtiin esitutkimusta tukitoiminnoista, joiden toiminnasta kaivoksella ei aikaisemmin ole ollut virallista selvitystä. Tämän tutkimuksen pohjalta voidaan Terrafame Oy:llä kohdentaa suunnittelun resursseja suoraan ongelmien juurisyiden ratkaisemiseen.Extensive analysis of the usability of the tertiary and quatenary crushing plants. Abstract. Over the years Terrafame Ltd has had challenges related to the ore crushers’ level measurement, which has created a feeling of an unreliable measurement. The purpose of this master’s thesis was to examine the current reliability of the level measurement, reveal challenges related to the measurement, and investigate the mechanisms behind the rapid and strong changes of the ore level. In addition, the crushers’ temperature measurement was examined along with the usability of auxiliaries within the crusher. This master’s thesis was done as an assignment for Terrafame Ltd during 1.2.2019–31.7.2019. The literature review covers the principles of statistical analysis and equipment effectiveness, in addition to the typically used methods of fault diagnostics. The master’s thesis was carried out as a statistical research with measurement data from the crushing plant, historical data of material consumption, and expert interviews. Crusher 342MRK0008 was fitted with an additional ore level sensor to examine the reliability of the standard level sensors. The reliability of the level measurement was improved by carrying out updates to the sensors, which enabled the use of the supplier’s latest technologies at the crushing plant. In addition, three work instructions were delivered for the level sensors. The temperature measurement of the crusher’s top bearing was found to be inaccurate, which was then corrected. The scope of the research of the crushers’ auxiliaries included the of top bearing greasing system, electrical pressure valve, and pressurized cleaning air. Technical reports of the top bearing greasing system and electrical pressure valve were delivered to Terrafame. This study included preliminary research of the auxiliaries, which the company had no previous official report of. This study provides a tool for Terrafame Ltd to target resources directly to solving the root causes of the problems

Bremsstrahlung Radiation as Coherent State in Thermal QED

Based on fully finite temperature field theory we investigate the radiation probability in the bremsstrahlung process in thermal QED. It turns out that the infrared divergences resulting from the emission and absorption of the real photons are canceled by the virtual photon exchange processes at finite temperature. The full quantum calculation results for soft photons radiation coincide completely with that obtained in the semi-classical approximation. In the framework of Thermofield Dynamics it is shown that the bremsstrahlung radiation in thermal QED is a coherent state, the quasiclassical behavior of the coherent state leads to above coincidence.Comment: 8 pages, 2 figure

Carbonyl compounds in boreal coniferous forest air in Hyytiälä, Southern Finland

International audienceA variety of C1-C12 carbonyl compounds were measured in the air of a boreal coniferous forest located in Hyytiälä, Southern Finland. 24-h samples were collected during March and April in 2003 using DNPH (2,4-dinitrophenyl hydrazine) coated C18-cartridges and analyzed by liquid chromatography-mass spectrometry (LC-MS). Altogether 22 carbonyl compounds were quantified. The most abundant carbonyls were acetone (24-h average 1340 ng/m3), formaldehyde (480 ng/m3) and acetaldehyde (360 ng/m3). In contrast, scaling of concentrations against reactivity with the hydroxyl (OH) radical significantly increased the contribution of larger aldehydes and ketones (e.g. decanal, octanal and 6-methyl-5-hepten-2-one). Concentrations of monoterpene reaction products nopinone (9 ng/m3) and limona ketone (5 ng/m3) were low compared to the most abundant low molecular weight carbonyls. The total concentration of carbonyl compounds in Hyytiälä in April/March 2003 was much higher than the concentration of aromatic hydrocarbons and monoterpenes in April 2002. Lifetimes of the measured carbonyls with respect to reactions with OH radicals, ozone (O3), and nitrate (NO3) radicals as well as photolysis were estimated. The main sinks for most of the carbonyl compounds in Hyytiälä in springtime are expected to be reactions with the OH radical and photolysis. For 6-methyl-5-hepten-2-one and limona ketone also reactions with ozone are important. The sources of carbonyl compounds are presently highly uncertain. Due to the relatively short lifetimes of aldehydes and ketones, secondary biogenic and anthropogenic sources, that is oxidation of volatile organic compounds, and primary biogenic sources are expected to dominate in Hyytiälä

A refinement of the emission data for Kola Peninsula based on inverse dispersion modelling

Peer reviewe

Technical Note: Quantitative long-term measurements of VOC concentrations by PTR-MS ? measurement, calibration, and volume mixing ratio calculation methods

International audienceProton transfer reaction mass spectrometry (PTR-MS) is a technique for online measurements of atmospheric concentrations, or volume mixing ratios, of volatile organic compounds (VOCs). The aim of this paper is to give a detailed description of our measurement, calibration, and volume mixing ratio calculation methods, which have been designed for long-term stand-alone field measurements by PTR-MS. We also show how the information obtained from a calibration can be used to determine the instrument specific relative transmission curve, which enables quantitative mixing ratio calculation for VOCs which are not present in a calibration gas standard. To illustrate the functionality of our measurement, calibration, and calculation methods, we present a one-month period of ambient mixing ratio data measured in a boreal forest ecosystem at the SMEAR II station in southern Finland. During the measurement period 27 March?26 April 2007, the hourly averages of mixing ratios were 0.1?0.5 ppbv for formaldehyde, 0.2?3.0 ppbv for methanol, 0.04?0.39 ppbv for benzene, and 0.03?1.25 ppbv for monoterpenes