3,988 research outputs found
The Control System for a new Pixel Detector at the sLHC
For the upgrade of the LHC, the sLHC (super Large Hadron Collider), a new ATLAS Pixel Detector is planned, which will require a completely new control system. To reduce the material budget new power distribution schemes are under investigation, where the active power conversion is located inside the detector volume. Such a new power supply system will need new control strategies. Parts of the control must be located closer to the loads. The minimization of mass, the demand for less cables and the re-use of the outer existing services are the main restrictions to the design of the control system. The requirements of the DCS (Detector Control System) and a first concept will be presented. We will focus on a control chip which necessarily has to be implemented in the new system. A setup of discrete components has been built up to investigate and verify the chipâs requirements. We report on the status of the work
Upgrade of the BOC for the ATLAS Pixel Insertable B-Layer
The phase 1 upgrade of the ATLAS [1] pixel detector will be done by inserting a fourth pixel layer together with a new beampipe into the recent three layer detector. This new detector, the Insertable B-Layer (IBL) should be integrated into the recent pixel system with as few changes in services as possible, but deliver some advantages over the recent system. One of those advantages will be a new data transmission link from the detector modules to the off-detector electronics, requiring a re-design of the electro-optical converters on the off-detector side. First ideas of how to implement those, together with some ideas to reduce cost by increasing the systems throughput are discussed
Off-diagonal structure of neutrino mass matrix in see-saw mechanism and electron-muon-tau lepton universality
By a simple extension of the standard model in which ()
universality is not conserved, we present a scenario within the framework of
see-saw mechanism in which the neutrino mass matrix is strictly off-diagonal in
the flavor basis. We show that a version of this scenario can accomodate the
atmospheric neutrino oscillations and
oscillations claimed by the LSND collaboration.
PACS: 14.60.Pq; 14.60.St;13.15.+gComment: 5 pages, Revtex, 1 figure: The model accomodate another version which
explains atmospheric neutrino data and the observed solar neutrino
oscillations (large angle solution). In the previous version the value of
\lambda parameter is changed to the expected one. This version now
accomodates LSND result and solar neutrino oscillations (small angle MSW
solution
Detector Control System of the ATLAS Insertable B-Layer
soumis Ă publicationTo improve tracking robustness and precision of the ATLAS inner tracker an additional fourth pixel layer is foreseen, called Insertable B-Layer (IBL). It will be installed between the innermost present Pixel layer and a new smaller beam pipe and is presently under construction. As, once installed into the experiment, no access is available, a highly reliable control system is required. It has to supply the detector with all entities required for operation and protect it at all times. Design constraints are the high power density inside the detector volume, the sensitivity of the sensors against heatups, and the protection of the front end electronics against transients. We present the architecture of the control system with an emphasis on the CO2 cooling system, the power supply system and protection strategies. As we aim for a common operation of pixel and IBL detector, the integration of the IBL control system into the Pixel one will be discussed as well
Improved limits on nuebar emission from mu+ decay
We investigated mu+ decays at rest produced at the ISIS beam stop target.
Lepton flavor (LF) conservation has been tested by searching for \nueb via the
detection reaction p(\nueb,e+)n. No \nueb signal from LF violating mu+ decays
was identified. We extract upper limits of the branching ratio for the LF
violating decay mu+ -> e+ \nueb \nu compared to the Standard Model (SM) mu+ ->
e+ nue numub decay: BR < 0.9(1.7)x10^{-3} (90%CL) depending on the spectral
distribution of \nueb characterized by the Michel parameter rho=0.75 (0.0).
These results improve earlier limits by one order of magnitude and restrict
extensions of the SM in which \nueb emission from mu+ decay is allowed with
considerable strength. The decay \mupdeb as source for the \nueb signal
observed in the LSND experiment can be excluded.Comment: 10 pages, including 1 figure, 1 tabl
Coherent pion production in neutrino nucleus collision in the 1 GeV region
We calculate cross sections for coherent pion production in nuclei induced by
neutrinos and antineutrinos of the electron and muon type. The analogies and
differences between this process and the related ones of coherent pion
production induced by photons, or the (p,n) and reactions are
discussed. The process is one of the several ones occurring for intermediate
energy neutrinos, to be considered when detecting atmospheric neutrinos. For
this purpose the results shown here can be easily extrapolated to other
energies and other nuclei.Comment: 13 pages, LaTex, 8 post-script figures available at
[email protected]
Neutrino induced transitions between the ground states of the A=12 triad
Neutrino induced reactions on C, an ingredient of liquid
scintillators, have been studied in several experiments. We show that for
currently available neutrino energies, 300 MeV, calculated
exclusive cross sections CN for both muon
and electron neutrinos are essentially model independent, provided the
calculations simultaneously describe the rates of several other reactions
involving the same states or their isobar analogs. The calculations agree well
with the measured cross sections, which can be therefore used to check the
normalization of the incident neutrino spectrum and the efficiency of the
detector.Comment: 9 pages REVTEX, 2 postscript figures, text and figures available at
http://www.krl.caltech.edu/preprints/MAP.htm
Leptonic Decays of Heavy Quarks on the Lattice
The status of lattice calculations of heavy-light decay constants and of the
parameter is reviewed. After describing the lattice approach to heavy
quark systems, the main results are discussed, with special emphasis on the
systematic errors in present lattice calculations. A detailed analysis of the
continuum limit for decay constants is performed. The implications of lattice
results on studies of CP violation in the Standard Model are discussed.Comment: Invited review to be published in Int. J. Mod. Phys. A, 63 pages,
LaTeX, ijmpa1.sty (included), 8 postscript figure
Hierarchical Four-Neutrino Oscillations With a Decay Option
We present a new and novel synthesis of all existing neutrino data regarding
the disappearance and appearance of and . We assume four
neutrinos: , as well as a heavier singlet neutrino
of a few eV. The latter may decay into a massless Goldstone boson (the
singlet Majoron) and a linear combination of the doublet antineutrinos. We
comment on how this scenario may be verified or falsified in future
experiments.Comment: 13 pages, no figur
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