The Borexino detector at the Laboratori Nazionali del Gran Sasso Back, H.; Balata, M.; de Bellefon, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2009, Letnik:
600, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Borexino, a large volume detector for low energy neutrino spectroscopy, is currently running underground at the Laboratori Nazionali del Gran Sasso, Italy. The main goal of the experiment is the ...real-time measurement of sub-MeV solar neutrinos, and particularly of the monoenergetic (862
keV)
7Be electron capture neutrinos, via neutrino–electron scattering in an ultra-pure liquid scintillator. This paper is mostly devoted to the description of the detector structure, the photomultipliers, the electronics, and the trigger and calibration systems. The real performance of the detector, which always meets, and sometimes exceeds, design expectations, is also shown. Some important aspects of the Borexino project, i.e. the fluid handling plants, the purification techniques and the filling procedures, are not covered in this paper and are, or will be, published elsewhere (see Introduction and Bibliography).
Expertise Matters Manno, Edward M; Freeman, William D; Livesay, Sarah ...
Critical care medicine,
2016-November, 2016-11-00, 20161101, Letnik:
44, Številka:
11
Journal Article
Clinical and experimental studies clearly demonstrate that prolonged seizures and status epilepticus induce neuronal cell death in the brain. Recent evidence suggests that induction of apoptosis ...contributes greatly to seizure-induced brain damage. We recently demonstrated that intrahippocampal delivery of botulinum neurotoxin E (BoNT/E) in the rat hippocampus is able to prevent neuronal loss, which occurs after kainic-acid-induced seizures. Here, we investigated the molecular mechanisms of BoNT/E-mediated neuroprotection. We found that intrahippocampal administration of BoNT/E prevents the upregulation of apoptotic proteins (phosphorylated c-Jun and cleaved caspase 3), which occurs in hippocampal neurones following kainic acid seizures. These results demonstrate that the neuroprotective action of BoNT/E on seizure-injured hippocampal neurons involves the blockade of well-characterized apoptotic pathways.
Light concentrators for Borexino and CTF Oberauer, L.; Grieb, C.; Feilitzsch, F.von ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2004, Letnik:
530, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Light concentrators for the solar neutrino experiment Borexino and the Counting Test Facility (CTF) have been developed and constructed. They increase the light yield of these detectors by factors of ...2.5 and 8.8, respectively. Technical challenges like long-term stability in various media, high reflectivity and radiopurity have been addressed and the concepts to overcome these difficulties will be described. Gamma spectroscopy measurements of the concentrators show an upper limit of 12μBq/g for uranium and a value of 120μBq/g for thorium. Upper limits on other possible contaminations like 26Al are presented. The impact of these results on the performance of Borexino and the CTF are discussed and it is shown that the design goals of both experiments are fulfilled.
Pulse-shape discrimination with the Counting Test Facility Back, H.O.; Balata, M.; Bellini, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2008, 2008-1-00, 2008-01, Letnik:
584, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Pulse shape discrimination (PSD) is one of the most distinctive features of liquid scintillators. Since the introduction of the scintillation technique in the field of particle detection, many ...studies have been carried out to characterize intrinsic properties of the most common liquid scintillator mixtures in this respect. Several application methods and algorithms capable of achieving optimum discrimination performances have been developed. However, the vast majority of these studies have been performed on samples of small dimensions. The Counting Test Facility, prototype of the solar neutrino experiment Borexino, as a 4 ton spherical scintillation detector immersed in 1000 tons of shielding water, represents a unique opportunity to extend the small-sample PSD studies to a large-volume set-up. Specifically, in this work we consider two different liquid scintillation mixtures employed in CTF, illustrating for both the PSD characterization results obtained either with the processing of the scintillation waveform through the optimum Gatti's method, or via a more conventional discrimination approach based on the charge content of the scintillation tail. The outcomes of this study, while interesting per se, are also of paramount importance in view of the expected Borexino detector performances, where PSD will be an essential tool in the framework of the background rejection strategy needed to achieve the required sensitivity to the solar neutrino signals.
This paper is about a mechanical solution to vibration problem of a wrapper flow pack mechanism, which is used in packaging industry. The target mechanism is the welding head of the machine where the ...vibration is generated, due to eccentric masses rotating with a cut-on-the-fly motion law. Consequently, production rate is limited by the vibration at 200 pieces per minute. To reduce the vibration so that the production rate can exceed over 200 ppm, two ways of improvements are considered. The first one is optimizing the motion law. The other one consists in mechanical modifications which eliminates or balance out the inertia forces derived from the eccentric rotating mass. This research implements the second way of adding balance weights and discusses the properties of it. During analysis, the software ADAMS which provides kinematic simulation is used as the analytical tool to test and examine the solutions proposed.
The vibrational effects created by machines moving parts is strictly related with the characteristics of the law of motion they implement, both in case of cam-follower devices and in case of servo ...system electronic cam controls. One of the most effective way to prevent these harmful phenomena is to limit the harmonic content of the law of motion by designing their curve as a combination of few, low frequencies, sinusoidal curves, but this often makes difficult to satisfy other functional requirements like precision points or constant speed intervals. In this work an original method to solve this problem is illustrated. It adds to the programming language CamOMiLe new functions to assist the functional design of mechanisms. The combination of the classical theory results with the flexibility of CamOMiLe building block approach makes possible to address a large number of practical applications and two examples of them are illustrated.
We report on the study of a new liquid scintillator target for neutrino interactions in the framework of the research and development program of the Borexino solar neutrino experiment. The ...scintillator consists of 1,2-dimethyl-4-(1-phenylethyl)-benzene (phenyl-o-xylylethane, PXE) as solvent and 1,4-diphenylbenzene (para-Terphenyl, p-Tp) as primary and 1,4-bis(2-methylstyryl)benzene (bis-MSB) as secondary solute. The density close to that of water and the high flash point makes it an attractive option for large scintillation detectors in general. The study focused on optical properties, radioactive trace impurities and novel purification techniques of the scintillator. Attenuation lengths of the scintillator mixture of 12
m at 430
nm were achieved after purification with an alumina column. A radiocarbon isotopic ratio of
C
14
/
C
12
=
9.1
×
10
-
18
has been measured in the scintillator. Initial trace impurities, e.g.
238U
at
3.2
×
10
-
14
g
/
g
could be purified to levels below
1
×
10
-
17
g
/
g
by silica gel solid column purification.
A 4.8 m
3 unsegmented liquid scintillation detector at the underground Laboratori Nazionali del Gran Sasso has shown the feasibility of multi-ton low-background detectors operating to energies as low ...as 250 keV. Detector construction and the handling of large volumes of liquid scintillator to minimize the background are described. The scintillator, 1.5 g PPO/L-pseudocumene, is held in a flexible nylon vessel shielded by 1000 t of purified water. The active detector volume is viewed by 100 photomultipliers, which measure time and charge for each event, from which energy, position and pulse shape are deduced. On-line purification of the scintillator by water extraction, vacuum distillation and nitrogen stripping removed radioactive impurities. Upper limits were established of < 10
−7 Bq/kg-scintillator for events with energies 250 keV <
E < 800 keV, and < 10
−9 Bq/kg-scintillator due to the decay products of uranium and thorium. The isotopic abundance of
14C
12C
in the scintillator was shown to be approximately 10
−18 by extending the energy window of the detector to 25–250 keV. The
14C abundance and uranium and thorium levels in the CTF are compatible with the Borexino Solar Neutrino Experiment.
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