1,783 research outputs found
On the number of limit cycles of the Lienard equation
In this paper, we study a Lienard system of the form dot{x}=y-F(x),
dot{y}=-x, where F(x) is an odd polynomial. We introduce a method that gives a
sequence of algebraic approximations to the equation of each limit cycle of the
system. This sequence seems to converge to the exact equation of each limit
cycle. We obtain also a sequence of polynomials R_n(x) whose roots of odd
multiplicity are related to the number and location of the limit cycles of the
system.Comment: 10 pages, 5 figures. Submitted to Physical Review
Performance of Irradiated Thin Edgeless N-on-P Planar Pixel Sensors for ATLAS Upgrades
In view of the LHC upgrade phases towards the High Luminosity LHC (HL-LHC),
the ATLAS experiment plans to upgrade the Inner Detector with an all-silicon
system. Because of its radiation hardness and cost effectiveness, the n-on-p
silicon technology is a promising candidate for a large area pixel detector.
The paper reports on the joint development, by LPNHE and FBK of novel n-on-p
edgeless planar pixel sensors, making use of the active trench concept for the
reduction of the dead area at the periphery of the device. After discussing the
sensor technology, a complete overview of the electrical characterization of
several irradiated samples will be discussed. Some comments about detector
modules being assembled will be made and eventually some plans will be
outlined.Comment: 6 pages, 13 figures, to appear in the proceedings of the 2013 Nuclear
Science Symposium and Medical Imaging Conference. arXiv admin note: text
overlap with arXiv:1311.162
Electrical Characterization of a Thin Edgeless N-on-p Planar Pixel Sensors For ATLAS Upgrades
In view of the LHC upgrade phases towards the High Luminosity LHC (HL-LHC),
the ATLAS experiment plans to upgrade the Inner Detector with an all-silicon
system. Because of its radiation hardness and cost effectiveness, the n-on-p
silicon technology is a promising candidate for a large area pixel detector.
The paper reports on the joint development, by LPNHE and FBK of novel n-on-p
edgeless planar pixel sensors, making use of the active trench concept for the
reduction of the dead area at the periphery of the device. After discussing the
sensor technology, and presenting some sensors' simulation results, a complete
overview of the electrical characterization of the produced devices will be
given.Comment: 9 pages, 9 figures, to appear in the proceedings of the 15th
International Workshops on Radiation Imaging Detector
Development of Edgeless n-on-p Planar Pixel Sensors for future ATLAS Upgrades
The development of n-on-p "edgeless" planar pixel sensors being fabricated at
FBK (Trento, Italy), aimed at the upgrade of the ATLAS Inner Detector for the
High Luminosity phase of the Large Hadron Collider (HL-LHC), is reported. A
characterizing feature of the devices is the reduced dead area at the edge,
achieved by adopting the "active edge" technology, based on a deep etched
trench, suitably doped to make an ohmic contact to the substrate. The project
is presented, along with the active edge process, the sensor design for this
first n-on-p production and a selection of simulation results, including the
expected charge collection efficiency after radiation fluence of comparable to those expected at HL-LHC (about
ten years of running, with an integrated luminosity of 3000 fb) for the
outer pixel layers. We show that, after irradiation and at a bias voltage of
500 V, more than 50% of the signal should be collected in the edge region; this
confirms the validity of the active edge approach.Comment: 20 pages, 9 figures, submitted to Nucl. Instr. and Meth.
Novel Silicon n-on-p Edgeless Planar Pixel Sensors for the ATLAS upgrade
In view of the LHC upgrade phases towards HL-LHC, the ATLAS experiment plans
to upgrade the Inner Detector with an all-silicon system. The n-on-p silicon
technology is a promising candidate for the pixel upgrade thanks to its
radiation hardness and cost effectiveness, that allow for enlarging the area
instrumented with pixel detectors. We report on the development of novel n-in-p
edgeless planar pixel sensors fabricated at FBK (Trento, Italy), making use of
the "active edge" concept for the reduction of the dead area at the periphery
of the device. After discussing the sensor technology and fabrication process,
we present device simulations (pre- and post-irradiation) performed for
different sensor configurations. First preliminary results obtained with the
test-structures of the production are shown.Comment: 6 pages, 5 figures, to appear in the proceedings of the 9th
International Conference on Radiation Effects on Semiconductor Materials
Detectors and Device
An analytical approximation scheme to two point boundary value problems of ordinary differential equations
A new (algebraic) approximation scheme to find {\sl global} solutions of two
point boundary value problems of ordinary differential equations (ODE's) is
presented. The method is applicable for both linear and nonlinear (coupled)
ODE's whose solutions are analytic near one of the boundary points. It is based
on replacing the original ODE's by a sequence of auxiliary first order
polynomial ODE's with constant coefficients. The coefficients in the auxiliary
ODE's are uniquely determined from the local behaviour of the solution in the
neighbourhood of one of the boundary points. To obtain the parameters of the
global (connecting) solutions analytic at one of the boundary points, reduces
to find the appropriate zeros of algebraic equations. The power of the method
is illustrated by computing the approximate values of the ``connecting
parameters'' for a number of nonlinear ODE's arising in various problems in
field theory. We treat in particular the static and rotationally symmetric
global vortex, the skyrmion, the Nielsen-Olesen vortex, as well as the 't
Hooft-Polyakov magnetic monopole. The total energy of the skyrmion and of the
monopole is also computed by the new method. We also consider some ODE's coming
from the exact renormalization group. The ground state energy level of the
anharmonic oscillator is also computed for arbitrary coupling strengths with
good precision.Comment: 5 pages, 3 tables, Late
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