The Monte San Nicola area (Southern Sicily) offers a spectacular exposure of open-marine sediments that were employed in 1998 for defining the Global Stratotype Section and Point (GSSP) of the ...Gelasian Stage (Upper Pliocene). After the lowering of the Pliocene/Pleistocene boundary to ca. 2.6 Ma in 2010, the Gelasian GSSP has been redefined as the base of both the Pleistocene Series and the Quaternary Period, which increased its importance and visibility within the scientific community. However, documentation on the Monte San Nicola reference section is still sparse. In the light of its renewed status, we decided to undertake a complete revision of the Gelasian Stage in its type area, in order to evaluate whether the succession of bio- and magnetostratigraphic events that are expected to occur in the interval of relevance are represented adequately in the local record. The results of our investigation demonstrate that the Monte San Nicola succession spans continuously from the upper Piacenzian to the lower Calabrian, and is therefore suitable to host the Unit Stratotype, or even the Astronomical Unit Stratotype, of the Gelasian Stage.
•Two sections from the Monte San Nicola area (Sicily) were studied.•The “Type” section (Gelasian Stage GSSP) suffers from local tectonic disturbances.•The undisturbed “Mandorlo” section offers a detailed biomagnetostratigraphic record.•Astronomical tuning further proves that the section is complete and continuous.•The Mandorlo section may host the Astronomical Unit-Stratotype of the Gelasian.
The MEG detector for μ+→e+γ decay search Adam, J.; Bai, X.; Baldini, A. M. ...
The European physical journal. C, Particles and fields,
04/2013, Letnik:
73, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The MEG (Mu to Electron Gamma) experiment has been running at the Paul Scherrer Institut (PSI), Switzerland since 2008 to search for the decay
μ
+
→e
+
γ
by using one of the most intense continuous
μ
...+
beams in the world. This paper presents the MEG components: the positron spectrometer, including a thin target, a superconducting magnet, a set of drift chambers for measuring the muon decay vertex and the positron momentum, a timing counter for measuring the positron time, and a liquid xenon detector for measuring the photon energy, position and time. The trigger system, the read-out electronics and the data acquisition system are also presented in detail. The paper is completed with a description of the equipment and techniques developed for the calibration in time and energy and the simulation of the whole apparatus.
We studied the distribution of deep water agglutinated foraminiferal (DWAF) assemblages across a 15-cm-thick volcaniclastic layer in the lower Campanian Scaglia Rossa limestones of the Umbria–Marche ...Basin. Above the volcaniclastic layer, which is devoid of foraminifera, a remarkable pattern of recovery among DWAF has been observed. The complete recovery of DWAF in terms of trophic groups and complexity of assemblages is observed in the first 5 cm above the volcaniclastic layer, representing 4.8 kyr based upon the mean sedimentation rate of the Campanian Scaglia Rossa Formation.
In its initial stage, the recovery pattern is remarkably similar to that observed following the 15 June 1991 Mount Pinatubo ashfall in the abyssal South China Sea where various species of
Reophax, a small organically cemented species of
Textularia, and the calcareous species
Quinqueloculina seminula and
Bolivina difformis are the earliest recolonisers on top of the tephra layer.
Such similarities between modern and fossil analogues strengthens the reliability of environmental reconstructions based on DWAF.
The Eocene–Oligocene transition marks the passage from ‘greenhouse’ conditions to an ‘icehouse’ state, with progressive global cooling starting in the early middle Eocene. The late Eocene presents ...substantial evidence for extraterrestrial impacts whose effects on living organisms and climatic changes are still not completely clear. A high‐resolution, microfloral and faunal investigation has been carried out in a 4‐m‐thick segment of the Massignano Global Stratotype Section and Point for the Eocene–Oligocene boundary. The studied interval includes a late Eocene (35.7 ± 0.4 Myr old) impactoclastic layer containing several cosmic signatures. The impact event recorded at Massignano had no abrupt, dramatic effects on marine biota in terms of extinction. However, significant quantitative changes in the calcareous plankton and dinoflagellate cyst assemblages occurred 60 kyr after the impact event. The observed pattern is intepreted as reflecting a long‐term re‐organization of water structure.
The integrated chemo-, bio- and sequence stratigraphy from the Cenomanian–Coniacian base-of-slope succession of Monte Turno (Abruzzo, central Italy) provides a fine scale calibration of the local ...sea-level curve inferred from the adjacent platform to records of global sea-level change. Our results indicate that regional marine regressions were coincident with episodes of global cooling and sea-level fall, providing evidences for a causal link between climate changes and sea-level changes. The presence of small polar ice-caps during the assumed ice-free Cretaceous is a likely explanation for the observed pattern.
The AMS-02 lead-scintillating fibres Electromagnetic Calorimeter Adloff, C.; Basara, L.; Bigongiari, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2013, Letnik:
714
Journal Article
Recenzirano
The Electromagnetic Calorimeter (ECAL) of the AMS-02 experiment is a fine grained lead-scintillating fibres sampling calorimeter that allows for a precise three-dimensional imaging of the ...longitudinal and lateral shower development. It provides a high (≥106) electron/hadron discrimination with the other AMS-02 detectors 1 and good energy resolution. The calorimeter also provides a standalone photon trigger capability to AMS-02. The mechanical assembly was realized to ensure minimum weight, still supporting the intrinsically heavy calorimeter during launch. ECAL light collection system and electronics are designed to measure electromagnetic particles over a wide energy range, from GeV up to TeV. A full-scale flight-like model was tested using electrons and proton beams with energies ranging from 6 to 250GeV.
The Online Silicon Vertex Tracker (SVT) is a new trigger processor dedicated to the 2-D reconstruction of charged particle trajectories at Level 2 of the CDF trigger. The SVT links the digitized ...pulse heights found within the Silicon Vertex detector to the tracks reconstructed in the Central Outer Tracker by the Level 1 Fast Track finder. The SVT was recently modified in order to increase its efficiency. The new configuration uses all the Silicon Vertex detector layers. On the other hand the processing time has increased. This can be a problem at higher luminosities of the Tevatron. The "Road Warrior" is a new board that eliminates redundant track candidates before Track Fitting. It is based on the principle of the Associative Memory. The algorithm used is described in the paper, as well as the hardware implementation.
The CDF online Silicon Vertex Tracker Ashmanskas, W.; Bardi, A.; Bari, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2002, Letnik:
485, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The CDF Online Silicon Vertex Tracker (SVT) reconstructs 2D tracks by linking hit positions measured by the Silicon Vertex Detector to the Central Outer Chamber tracks found by the eXtremely Fast ...Tracker (XFT). The system has been completely built and assembled and it is now being commissioned using the first CDF run II data. The precision measurement of the track impact parameter will allow triggering on B hadron decay vertices and thus investigating important areas in the B sector, like CP violation and B
s mixing. In this paper we briefly review the architecture and the tracking algorithms implemented in the SVT and we report on the performance of the system achieved in the early phase of CDF run II.
The data acquisition system for the ANTARES neutrino telescope Ameli, F.; Anton, G.; Anvar, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2007, 2007-1-00, Letnik:
570, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The ANTARES neutrino telescope is being constructed in the Mediterranean Sea. It consists of a large three-dimensional array of photo-multiplier tubes. The data acquisition system of the detector ...takes care of the digitisation of the photo-multiplier tube signals, data transport, data filtering, and data storage. The detector is operated using a control program interfaced with all elements. The design and the implementation of the data acquisition system are described.
At least since the middle Miocene (∼16 Ma), subduction erosion has been the dominant process controlling the tectonic evolution of the Pacific margin of Costa Rica. Ocean Drilling Program Site 1042 ...recovered 16.5 Ma nearshore sediment at ∼3.9 km depth, ∼7 km landward of the trench axis. The overlying Miocene to Quaternary sediment contains benthic foraminifera documenting margin subsidence from upper bathyal (∼200 m) to abyssal (∼2000 m) depth. The rate of subsidence was low during the early to middle Miocene but increased sharply in the late Miocene‐early Pliocene (5–6.5 Ma) and at the Pliocene‐Pleistocene boundary (2.4 Ma). Foraminifera data, bedding dip, and the geometry of slope sediment indicate that tilting of the forearc occurred coincident with the onset of rapid late Miocene subsidence. Seismic images show that normal faulting is widespread across the continental slope; however, extension by faulting only accounts for a minor amount of the post‐6.5 Ma subsidence. Basal tectonic erosion is invoked to explain the subsidence. The short‐term rate of removal of rock from the forearc is about 107–123 km3 Myr−1 km−1. Mass removal is a nonsteady state process affecting the chemical balance of the arc: the ocean sediment input, with the short‐term erosion rate, is a factor of 10 smaller than the eroded mass input. The low 10Be concentration in the volcanic arc of Costa Rica could be explained by dilution with eroded material. The late Miocene onset of rapid subsidence is coeval with the arrival of the Cocos Ridge at the subduction zone. The underthrusting of thick and thermally younger ocean crust decreased the subduction angle of the slab along a large segment of the margin and changed the dynamic equilibrium of the margin taper. This process may have induced the increase in the rate of subduction erosion and thus the recycling of crustal material to the mantle.
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