We present the results of a search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 20 GeV/c^{2} using a target of low-radioactivity argon with a 6786.0 kg d ...exposure. The data were obtained using the DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso. The analysis is based on the ionization signal, for which the DarkSide-50 time projection chamber is fully efficient at 0.1 keVee. The observed rate in the detector at 0.5 keVee is about 1.5 event/keVee/kg/d and is almost entirely accounted for by known background sources. We obtain a 90% C.L. exclusion limit above 1.8 GeV/c^{2} for the spin-independent cross section of dark matter WIMPs on nucleons, extending the exclusion region for dark matter below previous limits in the range 1.8-6 GeV/c^{2}.
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•Integrated study via ED-XRF and FTIR spectroscopies.•New study of materials at Lilybaeum, a Punic-Hellenistic archaeological site in Italy.•Identification of wall decoration ...pigments: from red ochre to manganese black.•Interpretation of spectroscopic results with respect to ancient painting techniques.
An integrated spectroscopic study of painted plaster fragments of the Punic-Hellenistic period (4th-1st century BCE) from the Lilybaeum archaeological site in Sicily is presented. Elemental and molecular composition of the painted wall fragments is obtained via ED-XRF and FTIR spectroscopies. This study is the first ever performed on finds from Lilybaeum urban area. A wide colour palette is identified examining a significant set of 14 polychrome wall plaster fragments. Hematite, orpiment, massicot, green earths, Egyptian blue, and manganese black are discovered. Based on interdisciplinarity, this work spans from chemistry/physics to archaeology through the interpretation of the spectroscopic results in the ancient Mediterranean context. The methodological approach used may be extended to other similar projects.
A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised
e
±
p
scattering at HERA during the ...period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared,
Q
2
, and in Bjorken
x
. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions, HERAPDF1.0, with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result.
Particle identification techniques are fundamental tools in nuclear physics experiments. Discriminating particles or nuclei produced in nuclear interactions allows to better understand the underlying ...physics mechanisms. The energy interval of these reactions is very broad, from sub-eV up to TeV. For this reason, many different identification approaches have been developed, often combining two or more observables. This paper reviews several of these techniques with emphasis on the expertise gained within the current nuclear physics scientific program of the Italian Istituto Nazionale di Fisica Nucleare (INFN).
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:
36
Ar
,
38
Ar
, and
40
Ar
. 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.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Abstract A measurement of the transverse momentum spectra of jets in Pb-Pb collisions at ... = 2.76TeV is reported. Jets ...are reconstructed from charged particles using the anti-k ^sub T^ jet algorithm with jet resolution parameters R of 0.2 and 0.3 in pseudo-rapidity |eta| < 0.5. The transverse momentum p ^sub T^ of charged particles is measured down to 0.15 GeV/c which gives access to the low p ^sub T^ fragments of the jet. Jets found in heavy-ion collisions are corrected event-by-event for average background density and on an inclusive basis (via unfolding) for residual background fluctuations and detector effects. A strong suppression of jet production in central events with respect to peripheral events is observed. The suppression is found to be similar to the suppression of charged hadrons, which suggests that substantial energy is radiated at angles larger than the jet resolution parameter R = 0.3 considered in the analysis. The fragmentation bias introduced by selecting jets with a high p ^sub T^ leading particle, which rejects jets with a soft fragmentation pattern, has a similar effect on the jet yield for central and peripheral events. The ratio of jet spectra with R = 0.2 and R = 0.3 is found to be similar in Pb-Pb and simulated PYTHIA pp events, indicating no strong broadening of the radial jet structure in the reconstructed jets with R < 0.3. Figure not available: see fulltext.
Abstract
Marfan syndrome is a connective tissue disease whose most fearsome complications are proximal thoracic aorta enlargement and dissection. Nonetheless, cardiac surgery has proven to be able to ...considerably extend average life expectancy up to approximately 70 years1. The aim of our study was to analyze which procedures had been performed on these patients. From 2000 to 2020 we retrospectively enrolled 89 consecutive patients undergoing a first–time surgical operation at our department. Overall, aortic root surgery represented the most frequent procedure (82 patients, 92.2%), with valve–sparing operation being the preferred one (53 patients, 59.6%). On the other hand, 29 patients (32.6%) underwent Bentall–De Bono procedure. Consequently, we compared these 2 groups of patients. In emergent operation, typically type A aortic dissection, Bentall–De Bono procedure was preferred in almost all cases (p–value 0.031). Few patients required the replacement of part or all of the arch, respectively 3 and 6, with no statistical difference between the two groups. However, while 2 valve–sparing patients required a mitral valve repair, 8 patients who underwent aortic root replacement had also their mitral valve replaced. Considering mean age (average 34.68 years), predictably almost all Bentall–De Bono patients had both their aortic and mitral valve replaced with a mechanical prosthesis (respectively 27 and 7 out of 29 and 8). Although there was no significant difference, replacement of the aortic root with a composite graft required less cross–clamp time, being also different the complexity of the technique. ICU stay was significantly different, since patients who had their aortic valve spared needed intensive assistance for an average of just 1.57 days, while the other group for 6.03 days (p–value 0.037). Similarly, but non significantly, hospital stay differed (13.91 and 18.17 days). Only 2 patients died during hospital recovery, both part of the Bentall–De Bono group (p–value 0.055). During the follow–up period (average 89.39 months), 6 patients died, 2 of them for noncardiac related causes, and 9 (11.3%) required another operation. In conclusion, Marfan syndrome is characterized by a dangerous proximal aorta involvement, which in some cases may be life–threatening if left untreated. Fortunately, surgery has significantly improved life quality and expectancy of these patients, who must be adequately diagnosed and then monitored by their referral centers.
Abstract
After its successful campaign of measurements beyond the Polar Arctic Circle, the PolarquEEEst experiment measured the cosmic charged particle rate at sea level in a latitude interval ...between 35
$$^{\circ }$$
∘
N and 82
$$^{\circ }$$
∘
N. In this paper, these measurements are described and the corresponding results are discussed.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Large liquid argon detectors offer one of the best avenues for the detection of galactic weakly interacting massive particles (WIMPs) via their scattering on atomic nuclei. The liquid argon target ...allows exquisite discrimination between nuclear and electron recoil signals via pulse-shape discrimination of the scintillation signals. Atmospheric argon (AAr), however, has a naturally occurring radioactive isotope, 39Ar, a β emitter of cosmogenic origin. For large detectors, the atmospheric 39Ar activity poses pile-up concerns. The use of argon extracted from underground wells, deprived of 39Ar, is key to the physics potential of these experiments. The DarkSide-20k dark matter search experiment will operate a dual-phase time projection chamber with 50 tonnes of radio-pure underground argon (UAr), that was shown to be depleted of 39Ar with respect to AAr by a factor larger than 1400. Assessing the 39Ar content of the UAr during extraction is crucial for the success of DarkSide-20k, as well as for future experiments of the Global Argon Dark Matter Collaboration (GADMC). This will be carried out by the DArT in ArDM experiment, a small chamber made with extremely radio-pure materials that will be placed at the centre of the ArDM detector, in the Canfranc Underground Laboratory (LSC) in Spain. The ArDM LAr volume acts as an active veto for background radioactivity, mostly γ-rays from the ArDM detector materials and the surrounding rock. This article describes the DArT in ArDM project, including the chamber design and construction, and reviews the background required to achieve the expected performance of the detector.
The Time-Of-Flight (TOF) detector of the ALICE experiment at the CERN LHC is based on Multi-gap Resistive Plate Chambers (MRPCs) technology. During the 2009-2013 data taking the TOF system had very ...stable operations with a total time resolution of 80ps. Details of the different calibration procedures and performance with data from collisions at the LHC will be described.
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