4,429 research outputs found
FELIX A full acceptance detector at the LHC
The FELIX collaboration has proposed the construction of a full acceptance
detector for the LHC, to be located at Intersection Region 4, and to be
commissioned concurrently with the LHC. The primary mission of FELIX is QCD: to
provide comprehensive and definitive observations of a very broad range of
strong-interaction processes. This paper reviews the detector concept and
performance characteristics, the physics menu, and plans for integration of
FELIX into the collider lattice and physical environment. The current status of
the FELIX Letter of Intent is discussed.Comment: 11 pages, 7 figures. To be published in "Proceedings of the XXVII
International Symposium on Multiparticle Dynamics, Frascati (Rome), Italy
8-12 Sept. 1997 (Nuclear Physics B, Proceedings Supplement)
Universal cross-over behavior of a magnetic impurity and consequences for doping in spin-1/2 chains
We consider a magnetic impurity in the antiferromagnetic spin-1/2 chain which
is equivalent to the two-channel Kondo problem in terms of the field
theoretical description. Using a modification of the transfer-matrix density
matrix renormalization group (DMRG) we are able to determine local and global
properties in the thermodynamic limit. The cross-over function for the impurity
susceptibility is calculated over a large temperature range, which exhibits
universal data-collapse. We are also able to determine the local
susceptibilities near the impurity, which show an interesting competition of
boundary effects. This results in quantitative predictions for experiments on
doped spin-1/2 chains, which could observe two-channel Kondo physics directly.Comment: 5 pages in revtex format including 3 embedded figures (using epsf).
The latest version in PDF format is available from
http://fy.chalmers.se/~eggert/papers/crossover.pdf . Accepted by PR
Precision orbit computations for an operational environment
Taking advantage of the improvements to the Earth's gravitation field and tracking station coordinates, an orbital computational consistency of the order of 5 meters was achieved for total position differences between orbital solutions for the Seasat and GEOS-3. The main source of error in these solutions was in the mathematical models that are required to generate these results, i.e., gravitation, atmospheric drag, etc. Different Earth gravitation fields and tracking coordinates were analyzed and evaluated in obtaining these computational results. Comparisons and evaluations of the Seasat results were obtained in terms of different solution types such as the Doppler only, Laser only, Doppler and Laser, etc. Other investigation using the Seasat data were made in order to determine their effect on the computational results at this particular level of consistency
FELIX, a full acceptance detector for the CERN LHC
Plans for FELIX, a full acceptance detector for the future CERN Large Hadron Collider (LHC), are described. The physics goals include detailed studies of the strong interactions (QCD), the forward energy flow and diffractive processes (Pomeron interactions), electroweak rapidity gaps, and elastic scattering. The precise measurement of particle production at a centre-of-mass energy of 14 TeV, well above the cosmic ray ``knee", will be fundamental for the interpretation of the highest energy cosmic ray events and may clarify some of the anomalies indicated by some cosmic ray experiments. The magnetic architecture and some of the design issues are briefly reviewed
Improving Small Object Proposals for Company Logo Detection
Many modern approaches for object detection are two-staged pipelines. The
first stage identifies regions of interest which are then classified in the
second stage. Faster R-CNN is such an approach for object detection which
combines both stages into a single pipeline. In this paper we apply Faster
R-CNN to the task of company logo detection. Motivated by its weak performance
on small object instances, we examine in detail both the proposal and the
classification stage with respect to a wide range of object sizes. We
investigate the influence of feature map resolution on the performance of those
stages.
Based on theoretical considerations, we introduce an improved scheme for
generating anchor proposals and propose a modification to Faster R-CNN which
leverages higher-resolution feature maps for small objects. We evaluate our
approach on the FlickrLogos dataset improving the RPN performance from 0.52 to
0.71 (MABO) and the detection performance from 0.52 to 0.67 (mAP).Comment: 8 Pages, ICMR 201
Phase diagram of an impurity in the spin-1/2 chain: two channel Kondo effect versus Curie law
We consider a magnetic s=1/2 impurity in the antiferromagnetic spin chain as
a function of two coupling parameters: the symmetric coupling of the impurity
to two sites in the chain and the coupling between the two sites .
By using field theory arguments and numerical calculations we can identify all
possible fixed points and classify the renormalization flow between them, which
leads to a non-trivial phase diagram. Depending on the detailed choice of the
two (frustrating) coupling strengths, the stable phases correspond either to a
decoupled spin with Curie law behavior or to a non-Fermi liquid fixed point
with a logarithmically diverging impurity susceptibility as in the two channel
Kondo effect. Our results resolve a controversy about the renormalization flow.Comment: 5 pages in revtex format including 4 embedded figures (using epsf).
The latest version in PDF format is available from
http://fy.chalmers.se/~eggert/papers/phase-diagram.pd
Letters between C. A. Eggert and William Kerr\u27s secretary
Letters concerning position in the modern languages department at Utah Agricultural College being filled
Letter from Emily S. Richards with a note from C. A. Eggert at the bottom
Letter concerning a recommendation
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