35 research outputs found

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

    Get PDF
    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

    Sensitivity projections for a dual-phase argon TPC optimized for light dark matter searches through the ionization channel

    Get PDF
    Dark matter lighter than 10  GeV/c2 encompasses a promising range of candidates. A conceptual design for a new detector, DarkSide-LowMass, is presented, based on the DarkSide-50 detector and progress toward DarkSide-20k, optimized for a low-threshold electron-counting measurement. Sensitivity to light dark matter is explored for various potential energy thresholds and background rates. These studies show that DarkSide-LowMass can achieve sensitivity to light dark matter down to the solar neutrino fog for GeV-scale masses and significant sensitivity down to 10  MeV/c2 considering the Migdal effect or interactions with electrons. Requirements for optimizing the detector’s sensitivity are explored, as are potential sensitivity gains from modeling and mitigating spurious electron backgrounds that may dominate the signal at the lowest energies

    Characterization of olive oils obtained fromwild olive trees (Olea ferruginea Royle) in Pakistan

    No full text
    Pakistan is lacking in edible oils and large amounts of resources are being used to import these. Olea ferruginea Royle (Oleaceae), locally known as Kahu, is native to Northern part of the country, and the fruit of this tree is currently not being utilized for any useful purpose. The present study was conducted to exploit a new source of virgin olive oil (OWOT) based on chemical composition and quality parameters. The fruits from wild olive trees were collected from different locations in Pakistan (i.e. Bhara Kahu, Kotli Sattian and Dir Swat); whereas a reference sample (OCOT) of a local variety (Zaitoon II) Olea europaea L. was collected from Barani Agricultural Research Institute, Chakwal (BARIC) for comparison. The basic quality characteristics of oils such as free acidity, peroxide value, specific UV absorptions and sensory analysis demonstrated that the oils belong to the \u201clampante olive oil\u201d commercial category due to low quality of processed olives. Some minor discrepancies with respect to the standard olive oil composition (linoleic acid slight exceeding 1% and traces of erucic acid and brassicasterol) were found that should be further studied to understand their etiology. Concerning minor compounds, tocopherols were found in low quantities whereas higher amounts of f-carotene and lutein were observed in OWOT compared to OCOT. Finally, OWOTs showed a relatively low quantity of hydrophilic phenols that proportionally expressed three times less antioxidant activity compared with OCOT. Careful control of fruit quality and good practices before olive milling could improve not only quality of the product, but also provide a new promising source of edible virgin oils

    A Probabilistic Energy-Aware Model for Mobile Ad-Hoc Networks

    Get PDF
    We propose a probabilistic, energy-aware, broadcast calculus for the analysis of mobile ad-hoc networks. The semantics of our model is expressed in terms of Segala’s probabilistic automata driven by schedulers to resolve the nondeterministic choice among the probability distributions over target states. We develop a probabilistic observational congruence and a energy-aware preorder semantics. The observational congruence allows us to verify whether two networks exhibit the same observable probabilistic behaviour (connectivity), while the preorder is used to compare the energy consumption of different, but behaviourally equivalent, networks. As an application, we analyse and compare the energy consumption of two well-known automatic repeat request (ARQ)-based error control protocols: stop-and-wait (SW) and go-back-N (GBN

    ESX1 gene expression as a robust marker of residual spermatogenesis in azoospermic men

    No full text
    Background It would be of value to identify ongoing spermatogenesis molecular markers which can predict successful sperm recovery in patients with non-obstructive azoospermia undergoing conventional or microsurgical testicular sperm extraction (TESE/microTESE). ESX1 is an X-linked homeobox gene expressed in testis, placenta, brain and lung in humans and specifically in pre-and post-meiotic germ cells of the testis in mice. Methods We investigated the sequence, expression (by RT-PCR) and epigenetic status (by promoter pyrosequencing) of ESX1 in testicular tissue samples, obtained from 81 azoospermic subjects in the context of surgical sperm extraction, to check a possible association between ESX1 alterations and impaired spermatogenesis, as determined by histological analysis. Result SThe ESX1 transcript was detected in 100 of cases diagnosed as obstructive azoospermia (33), hypospermatogenesis (18) and incomplete maturation arrest (MA) (2), and sperm recovery was also successful in 100 of these cases. ESX1 mRNA was also detected in 5 of 6 patients with incomplete Sertoli cell-only syndrome, in 4 of 6 subjects with complete MA but in only 3 of 16 cases of complete Sertoli cell-only syndrome (cSCOS), whereas sperm recovery was successful in 4 of 6, 2 of 6 and 5 of 16 of these patients, respectively. In cases of focal spermatogenesis, ESX1 expression and sperm retrieval were concordant in 14 of 19 (74) cases subjected to TESE, but in only 3 of 11 (27) men who underwent microTESE. With TESE, but not with microTESE, both samples originated from adjacent testicular areas. The pyrosequencing of the ESX1 CpG island revealed methylation levels that were significantly lower in ESX1 expressors when compared with non-expressors. Conclusions ESX1 emerges as a potentially reliable spermatogenesis molecular marker, whose clinical value as a predictor of successful sperm retrieval warrants further studies
    corecore