83 research outputs found

    Regulation of glycine catabolism in rat liver mitochondria

    Full text link

    Non-Virialized Axion Search Sensitive to Doppler Effects in the Milky Way Halo

    Full text link
    The Axion Dark Matter eXperiment (ADMX) has previously excluded Dine-Fischler-Srednicki-Zhitnisky (DFSZ) axions between 680-790 MHz under the assumption that the dark matter is described by the isothermal halo model. However, the precise nature of the velocity distribution of dark matter is still unknown, and alternative models have been proposed. We report the results of a non-virialized axion search over the mass range 2.81-3.31 {\mu}eV, corresponding to the frequency range 680-800 MHz. This analysis marks the most sensitive search for non-virialized axions sensitive to Doppler effects in the Milky Way Halo to date. Accounting for frequency shifts due to the detector's motion through the Galaxy, we exclude cold flow relic axions with a velocity dispersion of order 10^-7 c with 95% confidence

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

    Get PDF
    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

    Get PDF
    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

    Full text link
    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.

    Search for invisible axion dark matter in the 3.3-4.2 ÎĽeV mass range

    Get PDF
    We report the results from a haloscope search for axion dark matter in the 3.3-4.2 ÎĽeV mass range. This search excludes the axion-photon coupling predicted by one of the benchmark models of "invisible"axion dark matter, the Kim-Shifman-Vainshtein-Zakharov model. This sensitivity is achieved using a large-volume cavity, a superconducting magnet, an ultra low noise Josephson parametric amplifier, and sub-Kelvin temperatures. The validity of our detection procedure is ensured by injecting and detecting blind synthetic axion signals

    An Embodied Approach in a Cognitive Discipline

    Get PDF
    Academia can be an uncomfortable place to work. Academics are examples of professionals who have multiple stresses and pressures. Being an academic is often a fundamental part of someone’s identity. Academia can be a cerebral, critical, competitive and judgmental environment. This chapter draws from a study using creative research methods with academics who self-identified as having an embodied practice. There are different definitions of embodiment. I use embodiment to mean both a state of being and a process of learning about the self, and so embodied practices are ways of bringing conscious self-awareness to and about the body. The academics reflected on the meanings they attributed to these embodied practices, tensions with their embodied identity, and how they used them to impact on their wellbeing

    <span style="font-size:12.0pt;font-family: "Times New Roman";mso-fareast-font-family:"Times New Roman";mso-ansi-language: EN-GB;mso-fareast-language:EN-US;mso-bidi-language:AR-SA" lang="EN-GB">Synthesis, characterisation and antimicrobial activity of 3-methyl-6-(aryl)-1-phenyl-1<i style="mso-bidi-font-style:normal">H</i>-pyrazolo[3,4-<i style="mso-bidi-font-style: normal">b</i>]pyridine</span>

    No full text
    1767-1770A series of 3-methyl-6-(aryl)-1-phenyl-1H-pyrazolo[3,4-b]pyridine have been synthesized in one step by treating 5-azido-3-methyl-1-phenyl-1H-pyrazol-4-carboxaldehyde with suitably substituted acetophenones in basic medium. This reaction is a good example for in situ Friedlaender reaction. The newly synthesized compounds have been screened for their anti-microbial studies. All the compounds show MIC at low concentration itself against the tested fungi
    • …
    corecore