Improving Photoelectron Counting and Particle Identification in Scintillation Detectors with Bayesian Techniques

Many current and future dark matter and neutrino detectors are designed to measure scintillation light with a large array of photomultiplier tubes (PMTs). The energy resolution and particle identification capabilities of these detectors depend in part on the ability to accurately identify individual photoelectrons in PMT waveforms despite large variability in pulse amplitudes and pulse pileup. We describe a Bayesian technique that can identify the times of individual photoelectrons in a sampled PMT waveform without deconvolution, even when pileup is present. To demonstrate the technique, we apply it to the general problem of particle identification in single-phase liquid argon dark matter detectors. Using the output of the Bayesian photoelectron counting algorithm described in this paper, we construct several test statistics for rejection of backgrounds for dark matter searches in argon. Compared to simpler methods based on either observed charge or peak finding, the photoelectron counting technique improves both energy resolution and particle identification of low energy events in calibration data from the DEAP-1 detector and simulation of the larger MiniCLEAN dark matter detector.Comment: 16 pages, 16 figure

The French Didactic Tradition in Mathematics

This chapter presents the French didactic tradition. It first describes theemergence and development of this tradition according to four key features (role ofmathematics and mathematicians, role of theories, role of design of teaching andlearning environments, and role of empirical research), and illustrates it through two case studies respectively devoted to research carried out within this traditionon algebra and on line symmetry-reflection. It then questions the influence of thistradition through the contributions of four researchers from Germany, Italy, Mexicoand Tunisia, before ending with a short epilogue

Measurement of isotopic separation of argon with the prototype of the cryogenic distillation plant Aria for dark matter searches

The Aria cryogenic distillation plant, located in Sardinia, Italy, is a key component of the DarkSide-20k experimental program for WIMP dark matter searches at the INFN Laboratori Nazionali del Gran Sasso, Italy. Aria is designed to purify the argon, extracted from underground wells in Colorado, USA, and used as the DarkSide-20k target material, to detector-grade quality. In this paper, we report the first measurement of argon isotopic separation by distillation with the 26 m tall Aria prototype. We discuss the measurement of the operating parameters of the column and the observation of the simultaneous separation of the three stable argon isotopes: 36Ar , 38Ar , and 40Ar . We also provide a detailed comparison of the experimental results with commercial process simulation software. This measurement of isotopic separation of argon is a significant achievement for the project, building on the success of the initial demonstration of isotopic separation of nitrogen using the same equipment in 2019

Study on cosmogenic activation above ground for the DarkSide-20k project

The activation of materials due to the exposure to cosmic rays may become an important background source for experiments investigating rare event phenomena. DarkSide-20k is a direct detection experiment for galactic dark matter particles, using a two-phase liquid argon time projection chamber filled with 49.7 tonnes (active mass) of Underground Argon (UAr) depleted in 39Ar. Here, the cosmogenic activity of relevant long-lived radioisotopes induced in the argon and other massive components of the set-up has been estimated; production of 120 t of radiopure UAr is foreseen. The expected exposure above ground and production rates, either measured or calculated, have been considered. From the simulated counting rates in the detector due to cosmogenic isotopes, it is concluded that activation in copper and stainless steel is not problematic. Activation of titanium, considered in early designs but not used in the final design, is discussed. The activity of 39Ar induced during extraction, purification and transport on surface, in baseline conditions, is evaluated to be 2.8% of the activity measured in UAr from the same source, and thus considered acceptable. Other products in the UAr such as 37Ar and 3H are shown to not be relevant due to short half-life and assumed purification methods

Directionality of nuclear recoils in a liquid argon time projection chamber

The direct search for dark matter in the form of weakly interacting massive particles (WIMP) is performed by detecting nuclear recoils (NR) produced in a target material from the WIMP elastic scattering. A promising experimental strategy for direct dark matter search employs argon dual-phase time projection chambers (TPC). One of the advantages of the TPC is the capability to detect both the scintillation and charge signals produced by NRs. Furthermore, the existence of a drift electric field in the TPC breaks the rotational symmetry: the angle between the drift field and the momentum of the recoiling nucleus can potentially affect the charge recombination probability in liquid argon and then the relative balance between the two signal channels. This fact could make the detector sensitive to the directionality of the WIMP-induced signal, enabling unmistakable annual and daily modulation signatures for future searches aiming for discovery. The Recoil Directionality (ReD) experiment was designed to probe for such directional sensitivity. The TPC of ReD was irradiated with neutrons at the INFN Laboratori Nazionali del Sud, and data were taken with 72 keV NRs of known recoil directions. The direction-dependent liquid argon charge recombination model by Cataudella et al. was adopted and a likelihood statistical analysis was performed, which gave no indications of significant dependence of the detector response to the recoil direction. The aspect ratio R of the initial ionization cloud is estimated to be 1.037 +/- 0.027 and the upper limit is R < 1.072 with 90% confidence levelComment: 20 pages, 10 figures, submitted to Eur. Phys. J.

Study of cosmogenic activation above ground for the DarkSide-20k experiment

The activation of materials due to exposure to cosmic rays may become an important background source for experiments investigating rare event phenomena. DarkSide-20k, currently under construction at the Laboratori Nazionali del Gran Sasso, is a direct detection experiment for galactic dark matter particles, using a two-phase liquid-argon Time Projection Chamber (TPC) filled with 49.7 tonnes (active mass) of Underground Argon (UAr) depleted in 39Ar. Despite the outstanding capability of discriminating / background in argon TPCs, this background must be considered because of induced dead time or accidental coincidences mimicking dark-matter signals and it is relevant for low-threshold electron-counting measurements. Here, the cosmogenic activity of relevant long-lived radioisotopes induced in the experiment has been estimated to set requirements and procedures during preparation of the experiment and to check that it is not dominant over primordial radioactivity; particular attention has been paid to the activation of the 120 t of UAr used in DarkSide-20k. Expected exposures above ground and production rates, either measured or calculated, have been considered in detail. From the simulated counting rates in the detector due to cosmogenic isotopes, it is concluded that activation in copper and stainless steel is not problematic. The activity of 39Ar induced during extraction, purification and transport on surface is evaluated to be 2.8% of the activity measured in UAr by DarkSide-50 experiment, which used the same underground source, and thus considered acceptable. Other isotopes in the UAr such as 37Ar and 3H are shown not to be relevant due to short half-life and assumed purification methods

Teaching and Learning of Calculus

This survey focuses on the main trends in the field of calculus education. Despite their variety, the findings reveal a cornerstone issue that is strongly linked to the formalism of calculus concepts and to the difficulties it generates in the learning and teaching process. As a complement to the main text, an extended bibliography with some of the most important references on this topic is included. Since the diversity of the research in the field makes it difficult to produce an exhaustive state-of-the-art summary, the authors discuss recent developments that go beyond this survey and put forward new research questions

МЕТОДИ ЛІКУВАННЯ ПЕРЕЛОМІВ НИЖНЬОЇ ЩЕЛЕПИ З ВРОДЖЕНОЮ ТА НАБУТОЮ АДЕНТІЄЮ (ОГЛЯД ЛІТЕРАТУРИ)

Fractures of the mandible (lower jaw) are a common occurrence and usually related tointerpersonal violence or road traffic accidents. Social, economic conditions lead to anincrease in the proportion of patients with acquired partial or complete adentia in thestructure of patients with mandibular fractures. Mandibular fractures in this group ofpatients may be treated using open (surgical) and closed (non-surgical) techniques.Fracture sites cannot be immobilized with ordinary intermaxillary fixation (IMF), usuallyother external or internal devices are used (i.e. plates and screws) to allow bone healing.A method of treatment with the use of mini-implants was also considered. Varioustechniques have been investigated, however uncertainty exists with respect to the specificindications for each approach.Objectives. Detailed analysis of modern sources of professional Ukrainian and foreignmedical literature on the effectiveness of treatment of mandibular fractures in patientswith acquired partial or complete adentia.Conclusions. Mandibular fractures in patients with acquired partial or complete adentiaare treated with surgical, orthopedic-conservative and combined methods that should beused for clearly defined indications, taking into account the following fundamentalcriteria: 1) substantiated and exhaustive priority of conservative methods; 2) localizationof the fracture, the nature of displacement of bone fragments or its absence; 3) the stateand number of teeth, the degree of atrophy of the mandible; 4) age and general conditionof the patient; 5) biomechanical features of the mandible for different types of fractures.Переломы нижней челюсти - распространенное явление и часто связано с межличностным насилием, дорожно-транспортными происшествиями. Социальные, экономические условия приводят к увеличению доли больных с приобретенной частичной или полной адентией в структуре больных с переломами нижней челюсти.Переломы нижней челюсти у таких пациентов можно лечить с помощью открытых (хирургических) и закрытых (нехирургических) методов. Места разрываневозможно зафиксировать с помощью классической межчелюстной фиксации(IMF), чаще используют внешние или внутренние устройства (то есть пластины ивинты), обеспечивающие заживление кости. Рассмотрено также метод лечения сиспользованием мини-имплантатов. Были исследованы различные методики,однако существует неопределенность относительно конкретных показаний длякаждого подхода.Цель работы -провести анализ современных источников профессиональной отечественной и зарубежной медицинской литературы по эффективности леченияпереломов нижней челюсти у пациентов с приобретенной адентией.Выводы. Результаты изучения отечественной и зарубежной профессиональнойлитературы по лечению переломов нижней челюсти у пациентов с приобретеннойчастичной или полной адентией свидетельствуют, что оперативные, ортопедоконсервативные и комбинированные методы лечения следует применять по четкоопределенным показаниям, учитывая такие принципиальные критерии: 1) обоснована и исчерпывающая приоритетность консервативных методов; 2) локализация перелома, характер смещения костных фрагментов или его отсутствие; 3)состояние и количество зубов, степень атрофии нижней челюсти; 4) возраст иобщее состояние больного; 5) биомеханические особенности нижней челюсти приразличных типах переломов.Переломи нижньої щелепи - поширене явище і часто пов'язане з міжособистіснимнасильством, дорожньо-транспортними пригодами. Соціальні, економічні умовипризводять до збільшення частки хворих з набутою частковою або повноюадентією у структурі хворих з переломами нижньої щелепи. Переломи нижньоїщелепи у таких пацієнтів можна лікувати за допомогою відкритих (хірургічних) ізакритих (нехірургічних) методів. Місця розриву неможливо іммобілізувати задопомогою класичної міжщелепової фіксації (IMF), частіше використовуютьзовнішні чи внутрішні пристрої (тобто пластини і гвинти), що забезпечуютьзагоєння кістки. Розглянуто також метод лікування з використанням мініімплантатів. Були досліджені різні методики, однак існує невизначеність щодоконкретних показань для кожного підходу.Мета роботи - провести аналіз сучасних джерел фахової вітчизняної тазакордонної медичної літератури щодо ефективності лікування переломів нижньоїщелепи у пацієнтів з набутою адентією.Висновки. Результати вивчення вітчизняної та зарубіжної фахової літературищодо лікування переломів нижньої щелепи у пацієнтів з набутою частковою або жповною адентією засвідчують, що оперативні, ортопедично-консервативні та комбіновані методи лікування слід застосовувати за чітко визначеними показаннями,враховуючи такі принципові критерії: 1) обґрунтована та вичерпна пріоритетність консервативних методів; 2) локалізація перелому, характер зміщеннякісткових фрагментів або його відсутність; 3) стан і кількість зубів, ступіньатрофії нижньої щелепи; 4) вік і загальний стан хворого; 5) біомеханічніособливості нижньої щелепи за різних типів переломів

A compact, large-diameter adiabatic spinflipper for ultracold neutrons

We report the design and test of a compact, large-diameter spinflipper for ultracold neutrons based on the principle of adiabatic spinflip. A solenoid rf coil with a high diameter-to-length ratio (d/l~1.7) is surrounded by up to three short magnet coils (d/l~0.4...1.7) to provide the static gradient field. The device is optimized for low power consumption and operation in high vacuum. The magnetic field conditions necessary for full spinflipper efficiency over the full diameter were evaluated with ultracold neutrons. The measured spinflipper efficiency vs. adiabaticity correlation is in good agreement with a calculation based on an ideally linear gradient