Revealing neutral bremsstrahlung in two-phase argon electroluminescence

Proportional electroluminescence (EL) in noble gases has long been used in two-phase detectors for dark matter search, to record ionization signals induced by particle scattering in the noble-gas liquid (S2 signals). Until recently, it was believed that proportional electroluminescence was fully due to VUV emission of noble gas excimers produced in atomic collisions with excited atoms, the latter being in turn produced by drifting electrons. In this work we consider an additional mechanism of proportional electroluminescence, namely that of bremsstrahlung of drifting electrons scattered on neutral atoms (so-called neutral bremsstrahlung); it is systemically studied here both theoretically and experimentally. In particular, the absolute EL yield has for the first time been measured in pure gaseous argon in the two-phase mode, using a dedicated two-phase detector with EL gap optically read out by cryogenic PMTs and SiPMs. We show that the neutral bremsstrahlung effect can explain two intriguing observations in EL radiation: that of the substantial contribution of the non-VUV spectral component, extending from the UV to NIR, and that of the photon emission at lower electric fields, below the Ar excitation threshold. Possible applications of neutral bremsstrahlung effect in two-phase dark matter detectors are discussed.Comment: 14 pages, 21 figures. Version3: new several paragraphs and references and a new figure adde

Further studies of proportional electroluminescence in two-phase argon

The study of proportional electroluminescence in two-phase argon is relevant in the field of noble-gas liquid detectors for dark matter search and low-energy neutrino experiments. In this work, we continued to study proportional electroluminescence (EL) in two-phase argon doped with a minor (9 ppm) admixture of nitrogen, in the VUV, UV and visible spectral ranges. We confirmed the effect of enhancement of the EL yield, as well as the presence of non-VUV component in addition to that of VUV, in proportional electroluminescence in two-phase Ar. On the other hand, the contribution of non-VUV component determined here within the model of N2 emission in the UV, turned out to be insufficient to explain the EL yield enhancement effect. Accordingly, the problem of proportional electroluminescence in two-phase Ar remains unresolved.Comment: 12 pages, 7 figures, 1 table. Presented at Instrumentation for Colliding Beam Physics Conference (INSTR17). To be published in JINS

Роль и значение тракторных батарей на вооружении русской армии в годы Первой мировой войны

В рамках данной статьи мы попытаемся в первом приближении рассмотреть тракторные батареи в составе русской армии в Первую мировую войну. Их формирование стало важной реакцией на новейшие тенденции реформирования отечественной артиллерии применительно к началу ХХ века. Тяжелая артиллерия стала подлинной фронтовой элитой русской армии новой эпохи. Материальная часть, круг выполняемых задач, даже высокий дух (столь выгодно отличавший от крепостной и осадной артиллерии предшествующей эпохи) позволяют нам сделать соответствующий вывод. Объединял и особый корпоративный дух, свойственный русской полевой тяжелой артиллерии эпохи Первой мировой войны. Особым был и порядок продвижения по службе в подразделениях тяжелой артиллерии в целом, и в тракторных батареях – в частности. Тракторные батареи стали, так сказать, «элитой элиты» – когда эффект умножался на специфику новейшей техники и особую тактику применения этой техники. За тракторами и их преемниками – артиллерийскими тягачами - было будущее, а опыт русской армии эпохи Первой мировой войны лег в основу последующего отечественного военного строительства и в формирование моторизованной артиллерии. Методы исследования: архивный, историко-сравнительный, историко-системный

Evidence for the production of Ar2∗−_2^{*-} metastable negative molecular ions in two-phase argon detectors for dark matter searches

The recent studies of electroluminescence (EL) properties in two-phase argon detectors for dark matter searches have revealed the presence of unusual delayed pulses in the EL signal in the form of two slow components with time constants of about 5 and 50 $\mu$s. These components were shown to be present in the charge signal itself, which clearly indicates that drifting electrons are temporarily trapped on two states of metastable negative argon ions which have never been observed before. In this work, using the pressure dependence of the ratio of slow component contributions measured in experiment, it is shown that these states are those of two types of metastable negative molecular ions, $\mathrm{Ar}_2^{*-}(b \ ^4\Sigma_u^-)$ and $\mathrm{Ar}_2^{*-}(a \ ^4\Sigma_g^+)$ for the higher and lower energy level respectively.Comment: 4 pages, 2 figure

Possible use of television broadcasting signals for wind meas- urements by the meteor radiolocation method -main theoretical as- pects and results of first experiments

Summary The possibility of using terrestrial television (TV) broadcast signals (TVBS) as sounding signals for mesosphere-lower thermosphere (MLT) wind measurements by the radio meteor method is investigated. Such approach allows to use external TV transmitters as sounding signal sources and consequently to reduce costs of measurements. It is shown that meteor trails in the area above the receiver should be selected to eliminate MLT wind measurement ambiguity. Results of experimental observations are presented. Validation of the results has been performed using datasets from the Thermosphere-IonosphereMesosphere Energetics and Dynamics (TIMED) satellite and a SKiYMET meteor radar (Collm Observatory, Germany). It is shown that the obtained experimental results and TIMED mean winds are correlated with a correlation coefficient of 0.58 (significance level 0.95 according to a t-test). The measurements show for the first time that terrestrial television broadcast signals can be used for MLT wind measurements and that the developed technique may be used for MLT wind monitoring on the base of the existing terrestrial TV broadcasting network. Zusammenfassung Es wird untersucht, inwieweit terrestrischer Fernsehsignale zur Sondierung des Windes in der Mesosphäre und unteren Thermosphäre genutzt werden können. Ein solcher Ansatz erlaubt es, externe Sender als Quelle zu verwenden und damit Kosten zu sparen. Es wird gezeigt, dass Meteorsignale im Raum über dem Empfänger genutzt werden können, welches die Uneindeutigkeit der Windsignale verringert. Ergebnisse eines Experiments werden gezeigt und anhand von TIMED-Satellitendaten und VHF-Radarmessungen validiert. Die Messungen zeigen zum ersten Mal die Möglichkeit einer Windmessung in der unteren Thermosphäre auf der Basis terrestrischer Fernsehsignale