10 research outputs found
Construction and Performance of Large-Area Triple-GEM Prototypes for Future Upgrades of the CMS Forward Muon System
At present, part of the forward RPC muon system of the CMS detector at the
CERN LHC remains uninstrumented in the high-\eta region. An international
collaboration is investigating the possibility of covering the 1.6 < |\eta| <
2.4 region of the muon endcaps with large-area triple-GEM detectors. Given
their good spatial resolution, high rate capability, and radiation hardness,
these micro-pattern gas detectors are an appealing option for simultaneously
enhancing muon tracking and triggering capabilities in a future upgrade of the
CMS detector. A general overview of this feasibility study will be presented.
The design and construction of small (10\times10 cm2) and full-size trapezoidal
(1\times0.5 m2) triple-GEM prototypes will be described. During detector
assembly, different techniques for stretching the GEM foils were tested.
Results from measurements with x-rays and from test beam campaigns at the CERN
SPS will be shown for the small and large prototypes. Preliminary simulation
studies on the expected muon reconstruction and trigger performances of this
proposed upgraded muon system will be reported.Comment: 7 pages, 25 figures, submitted for publication in conference record
of the 2011 IEEE Nuclear Science Symposium, Valencia, Spai
Test beam results of the GE1/1 prototype for a future upgrade of the CMS high- muon system
Gas Electron Multipliers (GEM) are an interesting technology under
consideration for the future upgrade of the forward region of the CMS muon
system, specifically in the endcap region. With a
sufficiently fine segmentation GEMs can provide precision tracking as well as
fast trigger information. The main objective is to contribute to the
improvement of the CMS muon trigger. The construction of large-area GEM
detectors is challenging both from the technological and production aspects. In
view of the CMS upgrade we have designed and built the largest full-size
Triple-GEM muon detector, which is able to meet the stringent requirements
given the hostile environment at the high-luminosity LHC. Measurements were
performed during several test beam campaigns at the CERN SPS in 2010 and 2011.
The main issues under study are efficiency, spatial resolution and timing
performance with different inter-electrode gap configurations and gas mixtures.
In this paper results of the performance of the prototypes at the beam tests
will be discussed
Local image registration by adaptive filtering
Abstract—We propose a new adaptive filtering framework for local image registration, which compensates for the effect of local distortions/displacements without explicitly estimating a distortion/displacement field. To this effect, we formulate local image registration as a two-dimensional (2-D) system identification problem with spatially varying system parameters. We utilize a 2-D adaptive filtering framework to identify the locally varying system parameters, where a new block adaptive filtering scheme is introduced. We discuss the conditions under which the adaptive filter coefficients conform to a local displacement vector at each pixel. Experimental results demonstrate that the proposed 2-D adaptive filtering framework is very successful in modeling and compensation of both local distortions, such as Stirmark attacks, and local motion, such as in the presence of a parallax field. In particular, we show that the proposed method can provide image registration to: a) enable reliable detection of watermarks following a Stirmark attack in nonblind detection scenarios, b) compensate for lens distortions, and c) align multiview images with nonparametric local motion. Index Terms—Adaptive filtering, image registration, local image registration, nonparametric image registration, stirmark recovery, watermark synchronization. I