With the experimental station STELLA (STELlar LAboratory) we will measure fusion cross sections of astrophysical relevance making use of the coincident detection of charged particles and gamma rays ...for background reduction. For the measurement of gamma rays from the de-excitation of fusion products a compact array of 36 UK FATIMA LaBr3 detectors is designed based on efficiency studies with Geant4. The photo peak efficiency in the region of interest compares to other gamma detection systems used in this field. The features of the internal decay of 138La is used in a background study to obtain an online calibration of the gamma detectors. Background data are fit to the Monte Carlo model of the self activity assuming crude exponential behavior of external background. Accuracy in the region of interest is of the order of some keV in this first study.
A new collaboration is being formed to develop a multi-kiloton Long-Baseline neutrino experiment that will be located at the Surf Underground Research Facility (SURF) in Lead, SD. In the present ...design, the detector will be located inside cryostats filled with 68,400 ton of ultrapure liquid argon (less than 100 parts per trillion of oxygen equivalent contamination). To qualify the membrane technology for future very large-scale and underground implementations, a strong prototyping effort is ongoing: several smaller detectors of growing size with associated cryostats and cryogenic systems will be designed and built at Fermilab and CERN. They will take physics data and test different detector elements, filtration systems, design options and installation procedures. In addition, a 35 ton prototype is already operational at Fermilab and will take data with single-phase detector in early 2016. After the prototyping phase, the multi-kton detector will be constructed. After commissioning, it will detect and study neutrinos from a new beam from Fermilab. These cryostats will be engineered, constructed, commissioned, and qualified by an international engineering team. This contribution presents the on-going effort on the development of the cryostats and details the requirements and the current status of the design.
.
Sub-barrier fusion of the two near-by systems
36
S +
50
Ti,
51
V has been measured at the Laboratori Nazionali di Legnaro (INFN). Motivation for the experiment came from the possible effect of the ...non-zero spin of the ground state of the
51
V nucleus on the sub-barrier excitation function, and in particular on the shape of the barrier distribution. No previous data were available for these two systems near the barrier. Our results show that the two measured excitation functions are very similar down to the level of 20-30μb. The same is true for the two barrier distributions. Coupled-channel calculations have been performed including the low energy excitations of both projectile and the two targets. We have indication that the low-lying levels in
51
V can be interpreted in the weak-coupling scheme, that is,
51
V (
I
) =
50
Ti(2
+
) ⊗
p
(1
f
7/2
) and that the extra proton in the
1
f
7
/
2
shell does not have a significant influence on sub-barrier fusion.
In the context of the Neutrino Platform, CERN has designed, constructed, and commissioned the proximity cryogenics systems that serve two CERN based large-scale prototypes of future neutrino ...detectors. Each of these prototypes features a high voltage time projection chamber placed inside a membrane cryostat being submerged in 600m3 of liquid argon at about 1.0 bar. A copper and molecular sieve based cryogenic purification system has to ensure that the argon in the cryostat has a contamination level below 100 ppt oxygen equivalent. The two proximity cryogenics systems provide the purging, cool-down, filling, normal operation and emptying modes for each cryostat. This paper reports on the design, construction and commissioning of the ProtoDUNE proximity cryogenics facilities.
The sub-barrier fusion excitation function of 40Ca + 96Zr has been measured down to cross sections ≃2.4 μb, i.e. two orders of magnitude smaller than obtained in a previous experiment, where the ...sub-barrier fusion of this system was found to be greatly enhanced with respect to 40Ca + 90Zr, and the need of coupling to transfer channels was suggested relying on coupled-channels calculations. The purpose of this work has been to investigate the behavior of 40Ca + 96Zr fusion far below the barrier, thereby disentangling the elusive interplay of effects due to inelastic couplings, transfer couplings and, possibly, the appearance of the fusion hindrance. The smooth trend of the excitation function has been found to continue, and the logarithmic slope increases very slowly. No indication of hindrance shows up, and a comparison with 48Ca + 96Zr is illuminating in this respect. A new CC analysis of the complete excitation function has been performed, including explicitly one- and two-nucleon Q>0 transfer channels. Such transfer couplings bring significant cross section enhancements, even at the level of a few μb. Locating the hindrance threshold, if any, in 40Ca + 96Zr would require challenging measurements of cross sections in the sub-μb range.
Low-to-medium temperature fluid reservoirs hosted in carbonate rocks are some of the most promising and unknown geothermal systems. Western Sicily is considered a key exploration area. This paper ...illustrate a multidisciplinary and integrated review of the existing geological, geochemical and geophysical data, mainly acquired during oil and gas explorations since the 1950s, specifically re-analyzed for geothermal purposes, has led to understanding the western Sicily geothermal system as a whole, and to reconstructing the modalities and particular features of the deep fluid circulation within the regional reservoir. The data review suggests the presence of wide groundwater flow systems in the reservoir beneath impervious cap rocks. We identified the main recharge areas, reconstructed the temperature distribution at depth, recognized zones of convective geothermal flow, and depicted the main geothermal fluid flow paths within the reservoir.
We believe that our reconstruction of geothermal fluid circulation is an example of the general behavior of low-to-medium enthalpy geothermal systems hosted in carbonate units on a regional scale. Due to the recent technological developments of binary plants, these systems have become more profitable, not only for geothermal direct uses but also for power production.
The Long Baseline Neutrino Facility (LBNF) serves to provide the infrastructure necessary to support the Deep Underground Neutrino Experiment (DUNE), a growing international experiment to study ...neutrino science and proton decay. Situated at the Sanford Underground Research Facility (SURF), in Lead, SD, USA, DUNE will employ detectors located within massive cryostats filled with a total of 68,400 tons of ultrapure liquid argon. LBNF provides the cryogenic infrastructure necessary to supply and maintain that argon throughout the life of DUNE, as it enables the study of neutrinos from a new and improved beamline from Fermilab, as well as the dynamics of supernovae responsible for producing the heavy elements necessary for life and the possibility of proton decay. This contribution presents the modes of operation, layout, and main features of the cryogenic systems at LBNF. Those systems expected performance, functional requirements, and overall design status is also featured.
Magma emplacement in the upper crust is often associated with crustal extension, whereby space for intrusions is made by dilation along transtensive and strike‐slip faults. The lenticular shape of ...several intrusions indicates that a further mechanism for magma intrusion is laccolith emplacement with roof uplift of the overburden. Additionally, melts exploit rheological discontinuities (e.g., sedimentary layering) during their ascent. We present an emplacement model for intrusion of the shallow level Gavorrano Granite (northern Apennine, Italy), which is located at the core of an open anticline. The shape of the intrusion and structural features of the host rocks are indicative of a synkinematic emplacement in a growing thrust anticline. Space was provided by the opening of dilatation zones at the core of anticline as a consequence of different amounts of translation between hanging wall and footwall units which were separated by evaporitic rocks. These evaporitic units acted as major décollement layers. Analog models provide results in good agreement with the structural setting of the anticline and emphasize the possibility that melts filled the dilatation zone, with the décollement layers further facilitating intrusion.
PDF
