49,872 research outputs found
The NEXT double beta decay experiment
No full textNEXT (Neutrino Experiment with a Xenon TPC) is a neutrinoless double- beta (ßß0¿) decay experiment at Laboratorio Subterra ´neo de Canfranc (LSC). It is an electroluminescent Time Projection Chamber filled with high pressure 136Xe gas with separated function capabilities for calorimetry and tracking. Energy resolution and background suppression are the two key features of any neutrinoless double beta decay experiment. NEXT has both good energy resolution (< 1% FWHM) and an extra handle for background identification provided by track reconstruction. We expect a background rate of 4 × 10-4 counts keV-1 kg-1 yr-1, and a sensitivity to the Majorana neutrino mass of between 80–160 meV (depending on NME) after a run of 3 effective years of the 100 kg scale NEXT-100 detector. The initial phase of NEXT-100, called NEW, is currently being commissioned at LSC. It will validate the NEXT background rate expectations and will make first measurements of the two neutrino ßß2¿ mode of 136Xe. Furthermore, the NEXT technique can be extrapolated to the tonne scale, thus allowing the full exploration of the inverted hierarchy of neutrino masses. These proceedings review NEXT R&D results, the status of detector commissioning at LSC and the NEXT physics case
The NEXT experiment
No full textNEXT (Neutrino Experiment with a Xenon TPC) is an experiment to search neutrinoless double beta decay processes (ßß0¿ßß0¿). The isotope chosen by NEXT is 136Xe. The NEXT technology is based in the use of time projection chambers operating at a typical pressure of 15 bar and using electroluminescence to amplify the signal (HPXe). The main advantages of the experimental technique are: a) excellent energy resolution; b) the ability to reconstruct the trajectory of the two electrons emitted in the decays, a unique feature of the HPXe which further contributes to the suppression of backgrounds; c) scalability to large masses; and d) the possibility to reduce the background to negligible levels thanks to the barium tagging technology (BaTa).
The NEXT roadmap was designed in four stages: i) Demonstration of the HPXe technology with prototypes deploying a mass of natural xenon in the range of 1 kg; ii) Characterisation of the backgrounds to the ßß0¿ßß0¿ signal and measurement of the ßß2¿ßß2¿ signal with the NEW detector, deploying 10 kg of enriched xenon and operating at the LSC; iii) Search for ßß0¿ßß0¿ decays with the NEXT-100 detector, which deploys 100 kg of enriched xenon; iv) Search for ßß0¿ßß0¿ decays with the BEXT detector, which will deploy masses in the range of the ton and will introduce two additional handles, only possible in a HPXe: a) A magnetic field, capable of further enhancing the topological signal of NEXT; and b) barium-tagging (a technique pioneered by the EXO experiment which is also accessible to NEXT).
The first stage of NEXT has been successfully completed during the period 2009–2013. The prototypes NEXT-DEMO (IFIC) and NEXT-DBDM (Berkeley) were built and operated for more than two years. These apparatuses have demonstrated the main features of the technology. The experiment is currently developing its second phase. The NEW detector is being constructed during 2014 and will operate in the LSC during 2015. The NEXT-100 detector will be built and commissioned during 2016 and 2017 and will start data taking in 2018. NEXT-100 could discover ßß0¿ßß0¿ processes if the period of the decay is equal or less than 6×10256×1025 year. The fourth phase of the experiment (BEXT) could start in 2020
The Structure of Scientific Collaboration Networks in Scientometrics
No full textThe structure of scientific collaboration networks in scientometrics was investigated at the level of individuals by using bibliographic data of all papers published in the international journal Scientometrics retrieved from the Science Citation Index (SCI) during 1978 to 2004. Combined analysis of social network analysis (SNA), co-occurrence analysis, cluster analysis and frequency analysis of words was explored to reveal: (1) The microstructure of the collaboration network on scientists’ aspects of scientometrics; (2) The major collaborative fields of the collaborative sub-networks; (3) The collaborative center of the collaboration network in scientometrics
Collaboration in Iranian Scientific Publications
No full textThis study looks at international collaboration in Iranian scientific publications through the ISI Science Citation Index® (SCI) for the years 1995-1999, inclusive. These results are compared to and contrasted with the earlier findings for the periods covering 1985-1994 (Osareh & Wilson 2000). The results of Iran's increasing productivity over a 15-year period are presented. Iran doubled its output in the first two five-year periods and increased 2.8-fold from the second to the third five-year period. The rise in Iran's scientific publication output is due mainly to factors such as the ending of the war, better economic conditions, recent changes in the Iranian government's policy, basic changes in the political environment brought about by the Reformers, expansion of the Iranian presses for national publications, and the recent return of a large number of students trained overseas through government scholarships. External changes also account for the increased productivity, e.g., the acceptance of three Iranian source journals by the SCI, increased access to international databases through the Internet and better electronic communication facilities for international collaboration. One of the most important and significant factors that caused this dramatic rise seems to be the government's research policies in the last few years. Since 1999, the Iran Science, Research and Technology Ministry, has encouraged researchers to publish their non-Farsi language articles in highly ranked international scientific journals, for example, by giving prizes to researchers who publish their articles in ISI-ranked journals
The Hunt for neutrinoless double beta decay with the NEXT experiment
No full textThe NEXT-100 detector will search for the neutrinoless double beta decay of Xe using an electroluminescent high-pressure xenon gas TPC filled with 100~kg of enriched Xe. An observation of this hypothetical process would establish a Majorana nature for the neutrino and prove the violation of lepton number. A scaled-down prototype, NEXT-DEMO, has been built to demonstrate the feasibility of the technology. NEXT-DEMO includes an energy plane made of PMTs and a tracking plane made of SiPMs. X-ray energy depositions, produced by the de-excitation of xenon atoms after their interaction with gamma rays, have been used to characterize the detector response. With this method, the released energy by gammas coming from Na source has been corrected, achieving an energy resolution of 5.691%FWHM and 1.62%FWHM at the 29.7 keV and 511 keV peaks respectively, which extrapolate to 0.62%FWHM and 0.73%FWHM at Q value of Xenon
The methodological status of co-authorship networks
No full textA powerful strategy within the study of collaboration
in science is to posit that co-authorship patterns
represent social networks.
It is prerequisite to an application of Social
Network Analysis (SNA) to define the network
entities. A network analysis of the inter-institutional
collaboration in COLLNET on the basis
of co-authorships was conducted. The study reveals
that it is crucial whether the co-authorship
itself is seen as an author's relational property or
as a social event that brings the authors together.
The former possibility is represented by a onemode
network in which each author can be related
to each other author. Quite distinct from
that are two-mode networks, the latter approach.
They consist of two single data sets in which relations
are only possible between different sets.
Different modes of representations require
different network approaches. One is that co-authorship
networks are seen as one-mode networks,
which has the advantage of the application
of a variety of measures. In contrast, twomode
networks, the other option, cannot be analysed
by standard techniques but its distinctive
features demand a new conceptualisation of
measures. In conclusion, the two-mode perspective
is more promising because it allows a dual
perspective on collaboration in science which includes
researchers as well as their scientific output
Energy calibration of the NEXT-White detector with 1% resolution near Q ββ of 136Xe
No full textArtículo escrito por un elevado número de autores. Solo se referencia el que aparece en primer lugar, el nombre del grupo de colaboración si hubiere y los autores pertenecientes a la UAM.Excellent energy resolution is one of the primary advantages of electroluminescent high-pressure xenon TPCs. These detectors are promising tools in searching for rare physics events, such as neutrinoless double-beta decay (ββ0ν), which require precise energy measurements. Using the NEXT-White detector, developed by the NEXT (Neutrino Experiment with a Xenon TPC) collaboration, we show for the first time that an energy resolution of 1% FWHM can be achieved at 2.6 MeV, establishing the present technology as the one with the best energy resolution of all xenon detectors for ββ0ν searchesThe NEXT Collaboration acknowledges support from the following agencies and institutions:
the European Research Council (ERC) under the Advanced Grant 339787-
NEXT; the European Union's Framework Programme for Research and Innovation Horizon
2020 (2014{2020) under the Marie Sk lodowska-Curie Grant Agreements No. 674896,
690575 and 740055; the Ministerio de Economía y Competitividad and the Ministerio
de Ciencia, Innovación y Universidades of Spain under grants FIS2014-53371-C04,
RTI2018-095979, the Severo Ochoa Program SEV-2014-0398 and the Mar a de Maetzu
Program MDM-2016-0692; the GVA of Spain under grants PROMETEO/2016/120 and
SEJI/2017/011; the Portuguese FCT under project PTDC/FIS-NUC/2525/2014, under
project UID/FIS/04559/2013 to fund the activities of LIBPhys, and under grants
PD/BD/105921/2014, SFRH/BPD/109180/2015 and SFRH/BPD/76842/2011; the U.S.
Department of Energy under contracts number DE-AC02-06CH11357 (Argonne National
Laboratory), DE-AC02-07CH11359 (Fermi National Accelerator Laboratory), DE-FG02-
13ER42020 (Texas A&M) and DE-SC0019223 / DE-SC0019054 (University of Texas at Arlington);
and the University of Texas at Arlington. DGD acknowledges Ramon y Cajal program
(Spain) under contract number RYC-2015-18820. We also warmly acknowledge the
Laboratori Nazionali del Gran Sasso (LNGS) and the Dark Side collaboration for their help
with TPB coating of various parts of the NEXT-White TPC. Finally, we are grateful to the
Laboratorio Subterr aneo de Canfranc for hosting and supporting the NEXT experimen
Development of NEW, towards the first physics results of NEXT
No full textThe NEXT ßß0¿ experiment will use a high-pressure gas electroluminescent TPC to search for the decay of Xe- 136. The development, construction and installation of NEXT-WHITE (NEW), the first radio-pure version of NEXT, will take place this year at Laboratorio Subterra ´neo de Canfranc. NEW will run initially using 10 kg of natural xenon during which time NEXT technology will be validated and the topological reconstruction algorithms refined. Moreover, the background model will be benchmarked using data. A second run will use enriched xenon and will make a first measurement of the two neutrino channel (ßß2¿) by NEXT. This poster will present the various technical aspects of the detector detailing the radio-pure solutions for a low backgorund experiment and the low noise, high resolution measurement of both energy and position
Co-authorship Network of Scientometrics Research Collaboration
No full textThis paper examines the co-authorship network in the field of scientometrics using social network analysis techniques with the aim of developing an understanding of research collaboration in this scientific community. Using co-authorship data from 3125 articles published in the journal Scientometrics with a time span of more than three decades (1980-2012), we construct an evolving co-authorship network and calculate three centrality measures (closeness, betweenness, and degree) for 3024 authors, 1207 institutions, 68 countries and 22 academic fields in this network. This paper also discusses the usability of centrality measures in author ranking, and suggests that centrality measures can be useful indicators for impact analysis. Findings revealed that scientometrics was not dominated by a couple of key researchers as quite a significant number of popular researchers were identified. The United States occupies the topmost position in all measures except for degree centrality. The most active, central and collaborative academic discipline in scientometrics is Information & Library Science
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