9,260 research outputs found
A review of advances in pixel detectors for experiments with high rate and radiation
The Large Hadron Collider (LHC) experiments ATLAS and CMS have established
hybrid pixel detectors as the instrument of choice for particle tracking and
vertexing in high rate and radiation environments, as they operate close to the
LHC interaction points. With the High Luminosity-LHC upgrade now in sight, for
which the tracking detectors will be completely replaced, new generations of
pixel detectors are being devised. They have to address enormous challenges in
terms of data throughput and radiation levels, ionizing and non-ionizing, that
harm the sensing and readout parts of pixel detectors alike. Advances in
microelectronics and microprocessing technologies now enable large scale
detector designs with unprecedented performance in measurement precision (space
and time), radiation hard sensors and readout chips, hybridization techniques,
lightweight supports, and fully monolithic approaches to meet these challenges.
This paper reviews the world-wide effort on these developments.Comment: 84 pages with 46 figures. Review article.For submission to Rep. Prog.
Phy
Challenges in Double Beta Decay
After nearly 80 years since the first guess on its existence, neutrino still
escapes our insight: the mass and the true nature (Majorana or Dirac) of this
particle is still unknown. In the past ten years, neutrino oscillation
experiments have finally provided the incontrovertible evidence that neutrinos
mix and have finite masses. These results represent the strongest demonstration
that the Standard Model of electroweak interactions is incomplete and that new
Physics beyond it must exist. None of these experimental efforts could however
shade light on some of the basic features of neutrinos. Indeed, absolute scale
and ordering of the masses of the three generations as well as charge
conjugation and lepton number conservation properties are still unknown. In
this scenario, a unique role is played by the Neutrinoless Double Beta Decay
searches: these experiments can probe lepton number conservation, investigate
the Dirac/Majorana nature of the neutrinos and their absolute mass scale
(hierarchy problem) with unprecedented sensitivity. Today Neutrinoless Double
Beta Decay faces a new era where large scale experiments with a sensitivity
approaching the so-called degenerate-hierarchy region are nearly ready to start
and where the challenge for the next future is the construction of detectors
characterized by a tonne-scale size and an incredibly low background, to fully
probe the inverted-hierarchy region. A number of new proposed projects took up
this challenge. These are based either on large expansions of the present
experiments or on new ideas to improve the technical performance and/or reduce
the background contributions. n this paper, a review of the most relevant
ongoing experiments is given. The most relevant parameters contributing to the
experimental sensitivity are discussed and a critical comparison of the future
projects is proposed.Comment: 70 pages, 16 figures, 6 tables. arXiv admin note: text overlap with
arXiv:1109.5515, arXiv:hep-ex/0501010, arXiv:0910.2994 by other author
Enabling Technologies for Silicon Microstrip Tracking Detectors at the HL-LHC
While the tracking detectors of the ATLAS and CMS experiments have shown
excellent performance in Run 1 of LHC data taking, and are expected to continue
to do so during LHC operation at design luminosity, both experiments will have
to exchange their tracking systems when the LHC is upgraded to the
high-luminosity LHC (HL-LHC) around the year 2024. The new tracking systems
need to operate in an environment in which both the hit densities and the
radiation damage will be about an order of magnitude higher than today. In
addition, the new trackers need to contribute to the first level trigger in
order to maintain a high data-taking efficiency for the interesting processes.
Novel detector technologies have to be developed to meet these very challenging
goals. The German groups active in the upgrades of the ATLAS and CMS tracking
systems have formed a collaborative "Project on Enabling Technologies for
Silicon Microstrip Tracking Detectors at the HL-LHC" (PETTL), which was
supported by the Helmholtz Alliance "Physics at the Terascale" during the years
2013 and 2014. The aim of the project was to share experience and to work
together on key areas of mutual interest during the R&D phase of these
upgrades. The project concentrated on five areas, namely exchange of
experience, radiation hardness of silicon sensors, low mass system design,
automated precision assembly procedures, and irradiations. This report
summarizes the main achievements
Resonant Elastic Soft X-Ray Scattering
Resonant (elastic) soft x-ray scattering (RSXS) offers a unique element,
site, and valence specific probe to study spatial modulations of charge, spin,
and orbital degrees of freedom in solids on the nanoscopic length scale. It
cannot only be used to investigate single crystalline materials. This method
also enables to examine electronic ordering phenomena in thin films and to zoom
into electronic properties emerging at buried interfaces in artificial
heterostructures. During the last 20 years, this technique, which combines
x-ray scattering with x-ray absorption spectroscopy, has developed into a
powerful probe to study electronic ordering phenomena in complex materials and
furthermore delivers important information on the electronic structure of
condensed matter. This review provides an introduction to the technique, covers
the progress in experimental equipment, and gives a survey on recent RSXS
studies of ordering in correlated electron systems and at interfaces
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