1,557 research outputs found
CMS Centres Worldwide: a New Collaborative Infrastructure
Abstract. The CMS Experiment at the LHC is establishing a global network of inter-connected "CMS Centres" for controls, operations and monitoring. These support: (1) CMS data quality monitoring, detector calibrations, and analysis; and (2) computing operations for the processing, storage and distribution of CMS data. We describe the infrastructure, computing, software, and communications systems required to create an effective and affordable CMS Centre. We present our highly successful operations experiences with the major CMS Centres at CERN, Fermilab, and DESY during the LHC first beam data-taking and cosmic ray commissioning work. The status of the various centres already operating or under construction in Asia, Europe, Russia, South America, and the USA is also described. We emphasise the collaborative communications aspects. For example, virtual co-location of experts in CMS Centres Worldwide is achieved using high-quality permanently-running "telepresence" video links. Generic Web-based tools have been developed and deployed for monitoring, control, display management and outreach. What is a CMS Centre and how is it used ? CMS is establishing a network of "CMS Centres Worldwide" at CERN, in the Americas, Asia, Australasia, and Europe. The current locations are shown in figure 1. The goal is to help all collaborators to participate effectively in the CMS research programme, irrespective of location A CMS Centre is a communications focal point for students, post-docs and faculty. It is a common (physical and virtual) workplace with easy access to up-to-date information via (Web) services. As seen in figures 2 and 3, which show the CMS Centre@CERN and the LHC@FNAL, there are numerous status and monitoring screens, interactive consoles, high quality video-conference systems [4], meeting rooms and outreach displays. CMS Centres are used for CMS operations, sub-detector data quality monitoring (DQM) A CMS Centre increases CMS visibility in the institute, helps attract new students, and supports outreach activities such as tours, discussions with physicists, live displays, posters, and other exhibits. CMS Centres may also be used for media events. For example, on the LHC First Beam Day event of 10 th Sept. 2008, the world's largest scientific press event since the moon landing, 37 media organizations visited the CMS Centre @ CERN from where BBC TV News broadcast worldwide throughout the day
High-spin structures of 136Cs
Odd-odd 136Cs nuclei have been produced in the 18O + 208Pb and 12C + 238U
fusion-fission reactions and their gamma rays studied with the Euroball array.
The high-spin level scheme has been built up to ~ 4.7 MeV excitation energy and
spin I ~ 16 hbar from the triple gamma-ray coincidence data. The configurations
of the three structures observed above ~ 2 MeV excitation energy are first
discussed by analogy with the proton excitations identified in the semi-magic
137Cs nucleus, which involve the three high-j orbits lying above the Z=50 gap,
pi g_{7/2}, pi d_{5/2} and pi h_{11/2}. This is confirmed by the results of
shell-model calculations performed in this work.Comment: 6 pages, 4 figures, 3 table
High-spin states with seniority v=4,4,6 in 119-126Sn
The 119-126Sn nuclei have been produced as fission fragments in two reactions
induced by heavy ions: 12C+238U at 90 MeV bombarding energy, 18O+208Pb at 85
MeV. Their level schemes have been built from gamma rays detected using the
Euroball array. High-spin states located above the long-lived isomeric states
of the even- and odd-A 120-126Sn nuclei have been identified. Moreover isomeric
states lying around 4.5 MeV have been established in 120,122,124,126Sn from the
delayed coincidences between the fission fragment detector SAPhIR and the
Euroball array. The states located above 3-MeV excitation energy are ascribed
to several broken pairs of neutrons occupying the nu h11/2 orbit. The maximum
value of angular momentum available in such a high-j shell, i.e. for
mid-occupation and the breaking of the three neutron pairs, has been
identified. This process is observed for the first time in spherical nuclei.Comment: 20 pages, 22 figures, 12 tables, accepted for publication in Physical
Review
Gas phase mean opacities for varying [M/H], N/O, and C/O
We present a set of gas-phase Planck mean and Rosseland mean opacity tables
applicable for simulations of star and planet formation, stellar evolution,
disk modelling at various metallicities in hydrogen-rich environments. The
tables are calculated for gas temperatures between 1000K and 10000K and total
hydrogen number densities between 10^2 cm^-3 and 10^17 cm^-3. The
carbon-to-oxygen ratio is varied from 0.43 to well above 2.0, the
nitrogen-to-oxygen ration between 0.14 and 100.0. The tables are calculated for
a range of metallicities down to [M/H]'= log N_M/N_H=-7.0. We demonstrate how
the mean opacities and the abundances of the opacity species vary with C/O,
N/O, and [M/H]'. We use the element abundances from Grevesse, Asplund & Sauval
(2007), and we provide additional tables for the oxygen-abundance value from
Caffau et al.(2008). All tables will be available online under
http://star-www.st-and.ac.uk/ch80/datasources.htmlComment: 10 pages, accepted for publication in MNRA
HST/NICMOS Imaging of Disks and Envelopes Around Very Young Stars
We present HST/NICMOS observations with 0.1" (15 AU) resolution of six young
stellar objects in the Taurus star-formation region. The targets of our survey
are three Class I IRAS sources (IRAS 04016+2610, IRAS 04248+2612, and IRAS
04302+2247) and three low-luminosity stars (DG Tau B, Haro 6-5B, and CoKu
Tau/1) associated with Herbig Haro jets. The broad-band images show that the
near-infrared radiation from these sources is dominated by light scattered from
dusty circumstellar material distributed in a region 10 - 15 times the size of
our solar system. Although the detailed morphologies of the individual objects
are unique, the observed young stellar objects share common features. All of
the circumstellar reflection nebulae are crossed by dark lanes from 500 - 900
AU in extent and from less than 50 to 350 AU in apparent thickness. The
absorption lanes extend perpendicular to known optical and millimeter outflows
in these sources. We interpret the dark lanes as optically thick circumstellar
disks seen in silhouette against bright reflection nebulosity. The bipolar
reflection nebulae extending perpendicular to the dust lanes appear to be
produced by scattering from the upper and lower surfaces of the disks and from
dusty material within or on the walls of the outflow cavities. Out of five
objects in which the central source is directly detected, two are found to be
subarcsecond binaries. This mini-survey is the highest resolution near-infrared
study to date of circumstellar environments around solar-type stars with age <=
1 Myr.Comment: 34 pages, 4 figures; also available at
http://spider.ipac.caltech.edu/staff/brandner/topics/disks/disks.html ;
accepted for publication in AJ (March 1999 issue
Constraining Proton Lifetime in SO(10) with Stabilized Doublet-Triplet Splitting
We present a class of realistic unified models based on supersymmetric SO(10)
wherein issues related to natural doublet-triplet (DT) splitting are fully
resolved. Using a minimal set of low dimensional Higgs fields which includes a
single adjoint, we show that the Dimopoulos--Wilzcek mechanism for DT splitting
can be made stable in the presence of all higher order operators without having
pseudo-Goldstone bosons and flat directions. The \mu term of order TeV is found
to be naturally induced. A Z_2-assisted anomalous U(1)_A gauge symmetry plays a
crucial role in achieving these results. The threshold corrections to
alpha_3(M_Z), somewhat surprisingly, are found to be controlled by only a few
effective parameters. This leads to a very predictive scenario for proton
decay. As a novel feature, we find an interesting correlation between the d=6
(p\to e^+\pi^0) and d=5 (p\to \nu-bar K+) decay amplitudes which allows us to
derive a constrained upper limit on the inverse rate of the e^+\pi^0 mode. Our
results show that both modes should be observed with an improvement in the
current sensitivity by about a factor of five to ten.Comment: 21 pages LaTeX, 2 figures, Few explanatory sentences and three new
references added, minor typos corrected
Pathotypic diversity of Hyaloperonospora brassicae collected from Brassica oleracea
Downy mildew caused by Hyaloperonospora brassicae is an economically destructive disease of brassica crops in many growing regions throughout the world. Specialised pathogenicity of downy mildews from different Brassica species and closely related ornamental or wild relatives has been described from host range studies. Pathotypic variation amongst Hyaloperonospora brassicae isolates from Brassica oleracea has also been described; however, a standard set of B. oleracea lines that could enable reproducible classification of H. brassicae pathotypes was poorly developed. For this purpose, we examined the use of eight genetically refined host lines derived from our previous collaborative work on downy mildew resistance as a differential set to characterise pathotypes in the European population of H. brassicae. Interaction phenotypes for each combination of isolate and host line were assessed following drop inoculation of cotyledons and a spectrum of seven phenotypes was observed based on the level of sporulation on cotyledons and visible host responses. Two host lines were resistant or moderately resistant to the entire collection of isolates, and another was universally susceptible. Five lines showed differential responses to the H. brassicae isolates. A minimum of six pathotypes and five major effect resistance genes are proposed to explain all of the observed interaction phenotypes. The B. oleracea lines from this study can be useful for monitoring pathotype frequencies in H. brassicae populations in the same or other vegetable growing regions, and to assess the potential durability of disease control from different combinations of the predicted downy mildew resistance genes
Molecular gas in the Andromeda galaxy
We present a new 12CO(J=1-0)-line survey of the Andromeda galaxy, M31,
covering the bright disk with the highest resolution to date (85 pc along the
major axis), observed On-the-Fly (in italics) with the IRAM 30-m telescope. We
discuss the distribution of the CO emission and compare it with the
distributions of HI and emission from cold dust traced at 175mum. Our main
results are: 1. Most of the CO emission comes from the radial range R=3-16 kpc,
but peaks near R=10 kpc. The emission is con- centrated in narrow, arm-like
filaments defining two spiral arms with pitch angles of 7d-8d. The average
arm-interarm brightness ratio along the western arms reaches 20 compared to 4
for HI. 2. For a constant conversion factor Xco, the molecular fraction of the
neutral gas is enhanced in the arms and decreases radially. The apparent
gas-to-dust ratios N(HI)/I175 and (N(HI)+2N(H2))/I175 increase by a factor of
20 between the centre and R=14 kpc, whereas the ratio 2N(H2)/I175 only
increases by a factor of 4. Implications of these gradients are discussed. In
the range R=8-14 kpc total gas and cold dust are well correlated; molecular gas
is better correlated with cold dust than atomic gas.Comment: 21 pages, 16 figures. Accepted for publication in A&
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