1,721,024 research outputs found

    Study on NaI(Tl) crystal at −35 °C for dark matter detection

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    We present the response of a NaI(Tl) crystal in terms of the light yield and pulse shape characteristics at two different temperatures: 22 °C (room temperature) and −35 °C (low temperature). The light yield is measured using 59.54keV γ-rays from a 241Am source relative to the mean charge of single photoelectrons. At the low temperature, we measure a 4.7 ± 1.3% increase in the light yield compared to that at room temperature. A significantly increased decay time is also observed at the low temperature. The responses to nuclear recoil events are measured using neutrons from a 252Cf source and compared to those to electron recoil events. The measured pulse shape discrimination (PSD) power of the NaI(Tl) crystal at the low temperature is found to be improved in the entire energy range studied because of the increased light yield and the different scintillation characteristics. We also find a 9.23 ± 0.26% increased quenching factor of α-induced events, which is the light yield ratio of α recoil to electron recoil, at the low temperature. This supports the possibility of an increased quenching factor of the nuclear recoil events that are known to have similar processes of dark matter interaction. The increased light yield and the improved PSD power of nuclear recoil events enhance the sensitivity for dark matter detection via dark matter–nuclei interactions.11Nsciescopu

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed

    Scintillation characteristics of a NaI(Tl) crystal at low-temperature with silicon photomultiplier

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    © 2022 IOP Publishing Ltd and Sissa Medialab.The scintillation characteristics of a thallium-doped sodium iodide (NaI(Tl)) crystal with dimensions of 0.6 cm× 0.6 cm× 2 cm were studied by attaching a silicon photomultiplier (SiPM) directly to the crystal over a temperature range of 93-300 K. The scintillation light output and decay time were measured by irradiating 59.54 keV γ-rays with a 241Am source. We observed an approximately 20% increase in the light yield at 230 K compared with that at room temperature. Under these conditions, NaI(Tl) crystals with SiPM readout can be suitable for future dark matter search detectors.11Nsciescopu
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