73 research outputs found
Performance of the Beetle readout chip for LHCb
Beetle is a 128-channel readout chip, which will be used in the silicon vertex detector, the pile-up veto counters and the silicon tracker of the LHCb experiment at CERN. A further application of the Beetle chip is the readout of the LHCb RICH, in case it is equipped with multi-anode PMTs.
The scope of this paper is the design changes leading to the latest version 1.3 of the Beetle readout chip. In addition, measurements on earlier versions and simulation results driving these changes are shown
SEU Robustness, Total Dose Radiation Hardness and Analogue Performance of the Beetle Chip
The Beetle is a 128 channel readout chip for silicon strip detectors in LHCb. In addition to the pipelined readout path known from the RD20 architecture which can be used either in analogue or binary mode, the Beetle features an additional prompt binary readout path, used for the LHCb pile-up veto counters and a triple-redundant layout of the control logic. It is manufactured in commercial 0.25 µm CMOS technology using radiation hard design techniques. In addition to a total dose irradiation with X-rays, an SEU irradiation test with 65 MeV protons was performed with Beetle1.3. The results of this test are presented together with new results from the Beetle versions 1.3, 1.4 and 1.5, which were submitted in the Beetle ER engineering run in May 2004
Enhanced Radiation Hardness and Faster Front Ends for the Beetle Readout Chip
This paper summarizes the recent progress in the development of the 128 channel pipelined readout chip Beetle, which is intended for the silicon vertex detector, the inner tracker, the pile-up veto trigger and the RICH detectors of LHCb.
Deficiencies found in the front end of the Beetle Version 1.0 and 1.1 chips resulted in the submissions of BeetleFE 1.1 and BeetleFE 1.2, while BeetleSR 1.0 implements test circuits to provide future Beetle chips with logic circuits hardened against single event upset (SEU).
Section I. motivates the development of new front ends for the Beetle chip, and section II. summarizes their concepts and construction. Section III. reports preliminary results from the BeetleFE 1.1 and BeetleFE 1.2 chips, while section IV. describes the BeetleSR 1.0 chip. An outlook on future test and development of the Beetle chip is given in section V
Inclusive Production Cross Sections from 920 GeV Fixed Target Proton-Nucleus Collisions
Inclusive differential cross sections and
for the production of \kzeros, \lambdazero, and
\antilambda particles are measured at HERA in proton-induced reactions on C,
Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to
GeV in the proton-nucleon system. The ratios of differential
cross sections \rklpa and \rllpa are measured to be and , respectively, for \xf . No significant dependence upon the
target material is observed. Within errors, the slopes of the transverse
momentum distributions also show no significant
dependence upon the target material. The dependence of the extrapolated total
cross sections on the atomic mass of the target material is
discussed, and the deduced cross sections per nucleon are
compared with results obtained at other energies.Comment: 17 pages, 7 figures, 5 table
The QCD transition temperature: results with physical masses in the continuum limit II.
We extend our previous study [Phys. Lett. B643 (2006) 46] of the cross-over
temperatures (T_c) of QCD. We improve our zero temperature analysis by using
physical quark masses and finer lattices. In addition to the kaon decay
constant used for scale setting we determine four quantities (masses of the
\Omega baryon, K^*(892) and \phi(1020) mesons and the pion decay constant)
which are found to agree with experiment. This implies that --independently of
which of these quantities is used to set the overall scale-- the same results
are obtained within a few percent. At finite temperature we use finer lattices
down to a <= 0.1 fm (N_t=12 and N_t=16 at one point). Our new results confirm
completely our previous findings. We compare the results with those of the
'hotQCD' collaboration.Comment: 19 pages, 8 figures, 3 table
Deciphering potential chemical compounds of gaseous oxidized mercury in Florida, USA
The highest mercury (Hg) wet deposition in the United States of America (USA)
occurs along the Gulf of Mexico, and in the southern and central Mississippi
River Valley. Gaseous oxidized Hg (GOM) is thought to be a major contributor
due to high water solubility and reactivity. Therefore, it is critical to
understand concentrations, potential for wet and dry deposition, and GOM
compounds present in the air. Concentrations and dry-deposition fluxes of GOM
were measured and calculated for Naval Air Station Pensacola Outlying Landing Field (OLF) in Florida using
data collected by a Tekran<sup>®</sup> 2537/1130/1135,
the University of Nevada Reno Reactive Mercury Active System (UNRRMAS) with
cation exchange and nylon membranes, and the Aerohead samplers that use
cation-exchange membranes to determine dry deposition. Relationships with
Tekran<sup>®</sup>-derived data must be interpreted
with caution, since the GOM concentrations measured are biased low depending on
the chemical compounds in air and interferences with water vapor and ozone.<br><br>Criteria air pollutants were concurrently measured.
This allowed for comparison and better understanding of GOM.<br><br>In addition to
other methods previously applied at OLF, use of the UNRRMAS provided a
platform for determination of the chemical compounds of GOM in the air.
Results from nylon membranes with thermal desorption analyses indicated seven GOM
compounds in this area, including HgBr<sub>2</sub>, HgCl<sub>2</sub>, HgO, Hg–nitrogen
and sulfur compounds, and two unknown compounds. This indicates that the site
is influenced by different gaseous phase reactions and sources. Using back-trajectory analysis during a high-GOM event related to high CO, but average
SO<sub>2</sub>, indicated air parcels moved from the free troposphere and across
Arkansas, Mississippi, and Alabama at low elevation (< 300 m). This event
was initially characterized by HgBr<sub>2</sub>, followed by a mixture of GOM
compounds. Overall, GOM chemistry indicates oxidation reactions with local
mobile source pollutants and long-range transport.<br><br>In order to develop methods to measure GOM concentrations and chemistry, and
model dry-deposition processes, the actual GOM compounds need to be known,
as well as their corresponding physicochemical properties, such as Henry's
Law constants
EXPLORING A ROLE FOR CHROMATIN-REMODELING ENZYMES IN OXIDATIVE STRESS AND CARDIOVASCULAR DISEASE
Binder K, Nessen E, Ollmann C, Sexauer A, Crosswhite P.
Gonzaga University, Spokane, WA.
Cardiovascular disease (CVD) is the leading cause of death in the United States and oxidative stress is one contributing factor to dysfunction of the cardiovascular system. Chromatin remodeling complexes (CRCs) are enzymes that aid the regulation of DNA-histone binding to alter gene expression. Two CRCs, brahma (BRM) and brahma-related gene 1 (BRG1), are known to increase oxidative stress in cancer models but their role in the adult vasculature is poorly understood. PURPOSE: To measure the expression of oxidative stress markers after knockdown of BRG1/BRM in human vascular smooth muscle cells (SMCs). METHODS: Adult human SMCs were cultured and BRG1 and BRM were knocked down via an interfering RNA approach. Total RNA was isolated and quantitative polymerase chain reaction was used to measure the expression of several oxidative stress-related genes. RESULTS: Analysis of gene expression of oxidative stress-related markers including cellular-myleocytomatosis (c-MYC), superoxide dismutase (SOD), NADPH oxidase 4 (NOX4) and human SHC‐transforming protein 1 (SHC1) are ongoing and will be discussed. Based on literature, we expect that the levels of c-MYC and SOD will increase, while NOX4 and SCH1 will decrease. CONCLUSION: Our attempts to establish preliminary evidence linking CRC regulation of oxidative stress in adult human SMCs. This would be the first report of CRC-mediated oxidative stress in the adult vasculature and may open novel research opportunities for studying oxidative stress and CVD
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