In the quest for particle dark matter and physics beyond the Standard Model, the possibility of the existence of neutral long-lived particles (LLPs) has been proposed. The MATHUSLA project has been ...designed to detect possible LLPs produced in LHC collisions with a surface detector built by exploiting existing technologies. The detector will be installed above one of the high-luminosity interaction regions of the LHC before the beginning of the Phase-2 operation. A small-scale MATHUSLA test detector implemented with two stations of scintillators from the D0 experiment and three stations of Resistive Plate Chambers originally designed for the ARGO experiment was installed and operated above the ATLAS interaction point in November 2017. Each RPC station consisted of two detector layers, about 7 m2 each, with orthogonal read-out strips. The results of the test run will be presented.
The ARGO-YBJ experiment is a full-coverage array of Resistive Plate Chambers (RPCs) covering a surface of 74 x 78 m super(2) surrounded by a guard ring. It has been running almost uninterruptedly ...with its complete layout since November 2007. However, the work to optimize the stability of the experimental setup is still going on. The recorded daily and seasonal changes of temperature and barometric pressure affect the behaviour of the detector, in particular the time resolution and somehow the efficiency. Here a procedure is described for the equalization and the stabilization of the detector response.
The extended TeV gamma-ray source ARGO J2031+4157 (or MGRO J2031+41) is positionally consistent with the Cygnus Cocoon discovered by Fermi-LAT at GeV energies in the Cygnus superbubble. Reanalyzing ...the ARGO-YBJ data collected from 2007 November to 2013 January, the angular extension and energy spectrum of ARGO J2031+4157 are evaluated. After subtracting the contribution of the overlapping TeV sources, the ARGO-YBJ excess map is fitted with a two-dimensional Gaussian function in a square region of 10degrees x 10degrees, finding a source extension sigma sub(ext)= 1degrees.8 + or - 0degrees.5. The observed differential energy spectrum is dN/dE = (2.5 + or - 0.4) x 10 super(-11) (E/1 TeV) super(-2.6+ or -0.3) photons cm super(-2) s super(-1) TeV super(-1), in the energy range 0.2-10 TeV. The angular extension is consistent with that of the Cygnus Cocoon as measured by Fermi-LAT and the spectrum also shows a good connection with the one measured in the 1-100 GeV energy range. These features suggest to identify ARGO J2031+4157 as the counterpart of the Cygnus Cocoon at TeV energies. The Cygnus Cocoon, located in the star-forming region of Cygnus X, is interpreted as a cocoon of freshly accelerated cosmic rays related to the Cygnus superbubble. The spectral similarity with supernova remnants (SNRs) indicates that the particle acceleration inside a superbubble is similar to that in an SNR. The spectral measurements from 1 GeV to 10 TeV allows for the first time to determine the possible spectrum slope of the underlying particle distribution. A hadronic model is adopted to explain the spectral energy distribution.
In the last few years, an intense R &D activity on particle detectors for future HEP applications has been carried on with the aim of developing new techniques as well as studying the performance of ...already existing detectors when operated in a high rate environment. As for Resistive Plate Chamber detectors, the main challenges to face are the improvement of their detection capabilities and longevity at very high-rates, and the search for new eco-friendly gasmixtures free from greenhouse components. Results obtained in the framework of the RPC ECOGas@GIF++ Collaboration on a thin-Resistive Plate Chamber exposed at the CERN Gamma Irradiation Facility and operated with eco-friendly gas mixtures based on Tetrafluoropropene and Carbon dioxide will be discussed in this paper.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Results obtained by the RPC ECOgas@GIF++ Collaboration, using Resistive Plate Chambers operated with new, eco-friendly gas mixtures, based on tetrafluoropropene and carbon dioxide, are shown and ...discussed in this paper. Tests aimed to assess the performance of this kind of detectors in high-irradiation conditions, analogous to the ones foreseen for the coming years at the Large Hadron Collider experiments, were performed, and demonstrate a performance basically similar to the one obtained with the gas mixtures currently in use, based on tetrafluoroethane, which is being progressively phased out for its possible contribution to the greenhouse effect. Long term aging tests are also being carried out, with the goal to demonstrate the possibility of using these eco-friendly gas mixtures during the whole High Luminosity phase of the Large Hadron Collider.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Resistive Plate Chamber detectors are largely used in current High Energy Physics experiments, typically operated in avalanche mode with large fractions of Tetrafluoroethane (C2H2F4), a gas recently ...banned by the European Union due to its high Global Warming Potential (GWP). An intense R&D activity is ongoing to improve RPC technology in view of future HEP applications. In the last few years the RPC EcoGas@GIF++ Collaboration has been putting in place a joint effort between the ALICE, ATLAS, CMS, LHCb/SHiP and EP-DT Communities to investigate the performance of present and future RPC generations with eco-friendly gas mixtures. Detectors with different layout and electronics have been operated with ecological gas mixtures, with and without irradiation at the CERN Gamma Irradiation Facility (GIF++). Results of these performance studies together with plans for an aging test campaign are discussed in this article.
The ARGO-YBJ air shower detector monitored the Crab Nebula gamma-ray emission from 2007 November to 2013 February. The integrated signal, consisting of ~3.3 x 10 super(5) events, reached the ...statistical significance of 21.1 standard deviations. The obtained energy spectrum in the energy range 0.3-20 TeV can be described by a power law function dN/dE = I sub(0) (E/2 TeV) super(-alpha), with a flux normalization I sub(0) = (5.2 + or - 0.2) x 10 super(-12) photons cm super(-2) s super(-1) TeV super(-1) and alpha = 2.63 + or - 0.05, corresponding to an integrated flux above 1 TeV of 1.97 x 10 super(-11) photons cm super(-2) s super(-1). The systematic error is estimated to be less than 30% for the flux normalization and 0.06 for the spectral index. Assuming a power law spectrum with an exponential cutoff dN/dE = I sub(0) (E/2 TeV) super(-alpha) exp (-E/E sub(cut)), the lower limit of the cutoff energy E sub(cut) is 12 TeV, at 90% confidence level. Our extended data set allows the study of the TeV emission over long timescales. Over five years, the light curve of the Crab Nebula in 200-day bins is compatible with a steady emission with a probability of 7.3 x 10 super(-2). A correlated analysis with Fermi-LAT data over ~4.5 yr using the light curves of the two experiments gives a Pearson correlation coefficient r = 0.56 + or - 0.22. Concerning flux variations on timescales of days, a "blind" search for flares with a duration of 1-15 days gives no excess with a significance higher than four standard deviations. The average rate measured by ARGO-YBJ during the three most powerful flares detected by Fermi-LAT is 205 + or - 91 photons day super(-1), consistent with the average value of 137 + or - 10 day super(-1).
Abstract
This paper studies the performance of RPCs working with a new family of environment-friendly gases, mainly based on Carbon Dioxide and Hydro-Fluoro-Olefins. The tests are carried out on a 2 ...mm gap RPC and concern the measurement of detection efficiency, avalanche-to-streamer transition probability, prompt and ionic charge delivered. The timing properties of the new gas are also measured.
The upgrade of the Resistive Plate Chamber (RPC) detector, in order to increase the detector rate capability and to be able to work efficiently in high rate environment, consists in the reduction of ...the operating voltage along with the detection of signals which are few hundred μV small. The approach chosen by this project to achieve this objective is to develop a new kind of Front End electronics which, thanks to a mixed technology in Silicon and Silicon-Germanium, enhance the detector performances increasing its rate capability. The Front End developed is composed by a preamplifier in Silicon BJT technology with a very low inner noise (1000 e− rms) and an amplification factor of 0.3–0.4 mV/fC and a new kind of discriminator in SiGe HJT technology which allows a minimum threshold of the order of 0.5 mV. The performances of this kind of Front End will be shown. The results are obtained by using the CERN H8 beamline with a full-size RPC chamber of 1 mm gas gap and 1.2 mm thickness of electrodes equipped with this kind of Front End electronics.
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