20 years of cryogenic particle detectors: past, present and future

In 1984 different authors presented a new approach for detecting elementary particles: the cryogenic (sometimes also called bolometric) particle detector. The basic idea was very simple but at the same time completely different with respect to other classical methods. The generation of the signal is produced by phonons with a mean energy around 10 −4 − 10 −5 eV and this aspect changes completely the evaluation of the theoretical energy resolution. In these 20 years substantial progress has been made in the development of cryogenic particle detectors, many experiments have been realized and some are still running. Detector performances are greatly improved and very massive detectors have been constructed. For specific experiments, detectors with simultaneous measurements of heat and ionization (or scintillation) were also developed. Cryogenic particle detectors have been applied in many fields, not only in particle physics experiments, thanks to some peculiar characteristics that they exhibit. Experiments on double beta decay take advantage from the good energy resolution and the flexibility in selecting materials; low energy thresholds and high efficiencies to nuclear recoils of these detectors are very interesting in the search for dark matter; the impressively high energy resolution of microcalorimeters is suitable for X-ray spectroscopy and direct neutrino mass measurements. Other experiments in particle physics use the cryogenic approach, but it is important to note that applications to surface analysis with Total Reflection X-ray Fluorescence (TXRF) for industry and measurements of protein fragments for biology have been also proposed. In the near future, new experiments will be realized using this technique. Very important technical challenges are still open, such as: realization of very large detectors (at the one ton scale), improvements in energy resolution and energy thresholds, maximization of the time resolution. A short history and the state of the art of cryogenic particle detectors will be presented; some aspects of their applications in the past and for the future will be briefly discussed

High-purity material selection techniques for Rare-Events Physics experiments

In experiments on Rare-Events Physics it is important that the construction materials, in particular those closer to the detectors, have the smallest amount of contaminants that can contribute to background. Copper is a material widely used thanks to its low content in radioactive contaminants, so it is very important to develop tools able to reach high sensitivity in the analysis of Copper radioactivity. A method based on Neutron Activation Analysis (NAA) has been developed to analyze 232Th contamination in copper samples through the irradiation of 200 g of copper then radiochemical concentrated using nitric acid and actinide resin. Several elutions with various inorganic acids were done to concentrate 233Pa, activation product of 232Th, from copper matrix to eliminate radioactive contribution from other activation products. Using gamma spectroscopy with HPGe to evaluate the radioactivity due to gamma rays from 233Pa decay it was possible to reach a detection limit of 5 × 10−13g232Th/gCu

Scintillating double beta decay bolometers

We present the results obtained in the development of scintillating Double Beta Decay bolometers. Several Mo and Cd based crystals were tested with the bolometric technique. The scintillation light was measured through a second independent bolometer. A 140 g CdWO_4 crystal was run in a 417 h live time measurement. Thanks to the scintillation light, the alpha background is easily discriminated resulting in zero counts above the 2615 keV gamma line of Thallium 208. These results, combined with an extremely easy light detector operation, represent the first tangible proof demonstrating the feasibility of this kind of technique.Comment: 15 pages, 8 figure

Electrochemistry of cyclic triimidazoles and their halo derivatives: A casebook for multiple equivalent centers and electrocatalysis

A family of cyclic triazines, based on the triimidazo[1,2-a:1\u2032,2\u2032-c:1\u2033,2\u2033-e][1,3,5]triazine scaffold, has recently caught attention due to its variegated solid state photoluminescent properties (e.g., crystallization induced emission, fluomechanochromism, dual fluorescence, room temperature ultralong phosphorescence), tuned by proper functionalization of the cyclic core. From an electrochemical point of view, this family of heteroaromatic cyclic triazines is unexplored. A cyclic voltammetry study is here performed aiming to clarify structure/electroactivity relationship. The peculiar molecular structure of this class of molecules offers a multi-approach case study, spanning from multiple equivalent redox site interactions in small hoops (due to ideally C3h symmetry) to carbon-halogen bond reactivity in the presence of catalytic metal electrode surfaces (for \u2013Br and \u2013I derivatives). Results point to a poor heteroannular aromaticity along the rigid, planar cyclotrimer, with each equivalent redox site acting quite independently. An unusually higher electrocatalytic performance of gold with respect to silver electrode for the electrocleavage of carbon-halogen bonds (that decreases by increasing number of halo substituents) is tentatively explained in term of a specific interaction between gold and the nitrogen-rich planar cyclotrimer platform

Characterisation of the Thermal Damage in a Martensitic Steel Substrate Consequent to Laser Cladding Process

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Zystoskopie bei einem Rind mit Urachus persistens-Ruptur

Die Arbeit beschreibt die klinischen, sonographischen und zystoskopischen Befunde sowie die Therapie bei einem 2-jährigen, 7 Monate trächtigen Braunviehrind mit Ruptur des Urachus persistens. Das Leitsymptom war ein birnförmiges Abdomen bei stark gestörtem Allgemeinbefinden. Die Blutuntersuchung ergab eine hochgradige Azotämie. Bei der Ultraschalluntersuchung wurde ein Aszites festgestellt, welcher aufgrund der massiv erhöhten Kreatininkonzentration im Punktat als Uroperitoneum klassiert wurde. Bei der Zystoskopie konnte das Endoskop über die Harnblase in einen persistierenden Urachus eingeführt werden. Aufgrund sämtlicher Befunde wurde die Diagnose Uroperitoneum infolge Ruptur eines Urachus persistens gestellt. Als Therapie wurde eine Laparotomie in der linken Flanke mit doppelter Ligation des Urachus durchgeführt. Innerhalb von wenigen Tagen normalisierte sich der Zustand des Rindes. Es hat inzwischen normal gekalbt und erfreut sich bester Gesundheit This case report describes the clinical, ultrasonographic and cystoscopic findings and treatment in a two-year-old Swiss Braunvieh heifer with rupture of a patent urachus. The lead signs in the seven-month-pregnant heifer were markedly abnormal general condition and demeanour and a pear-shaped abdomen. The heifer had severe azotaemia, and abdominal ultrasonography revealed ascites, which was diagnosed as uroperitoneum based on an elevated creatinine level in the fluid. A patent urachus was identified during cystoscopy; the endoscope could be advanced beyond the apex of the urinary bladder into the urachus. Based on all the findings, a diagnosis of uroperitoneum attributable to rupture of a patent urachus was made. The urachus was ligated twice via a left-flank laparotomy. The general condition normalised within a few days of surgery, and the patient calved normally and was in good health at follow-up evaluation

Optimal scan planning for surveying large sites with static and mobile mapping systems

Since the last two decades, the use of laser scanners for generating accurate and dense 3D models has been rapidly growing in multiple disciplines. The reliance on human-expertise to perform an efficient scanning in terms of completeness and quality encouraged the researchers to develop strategies for carrying out an optimized and automated scan planning. Nevertheless, due to the predominant use of static terrestrial laser scanners (TLS), the most of developed methods have been focused on scan optimization by fixing standpoints on basis of static scanning. The increasing use of portable mobile laser scanning systems (MLS) enables faster non-stop acquisition which demands the planning of optimal scan trajectories. Therefore, a novel method addressing the absence of dynamic scan planning is proposed considering specific MLS constraints such as maximum acquisition time or closed-loops requirement. First, an initial analysis is carried out to determinate key-positions to reach during data acquisition. From these positions a navigable graph is generated to compute routes satisfying specific MLS constraints by a three-step process. This starts by estimating the number of routes necessary to subsequently carry out a coarse graph partition based on Kmedoids clustering. Next, a balancing algorithm was implemented to compute a balanced graph partition by node exchanging. Finally, partitions are extended by adding key nodes from their adjacent ones in order to provide a desirable overlapping between scans. The method was tested by simulating three laser scanner configurations in four indoor and outdoor real case studies. The acquisition quality of the computed scan planning was evaluated in terms of 3D completeness and point cloud density with the simulator Helios++