197497757
LATEST RESULTS FROM MINOS.
Among the goals of the MINOS experiment are the test of the {nu}{sub {mu}} {yields} {nu}{sub {tau}} oscillation and the search for sub-dominant {nu}{sub {mu}} {yields} {nu}{sub {tau}} oscillations. The former proceeds by a {nu}{sub {mu}} ''disappearance'' analysis while the latter would involve the ''appearance'' of {nu}{sub e} interactions in a predominantly {nu}{sub {mu}} beam. The disappearance of muon neutrinos is described by P({nu}{sub {mu}} {yields} {mu}{sub {mu}}) = 1 - sin{sup 2} 2{theta}{sub 23} sin{sup 2} (1.27 {Delta} m{sub 23}{sup 2} L/E) in the two-flavor approximation where {theta}{sub 23} is the angle between the second row and third column of the neutrino mixing matrix, {Delta}m{sub 23}{sup 2} = m{sub 2}{sup 2}-m{sub 3}{sup 2} (eV{sup 2}), L is the neutrino flight distance in km and E is the neutrino energy in GeV. A generic disappearance experiment compares a measured muon neutrino energy spectrum at a fixed baseline to the known energy spectrum of muon neutrino beam to extract the oscillation parameters sin{sup 2} 2{theta} which controls the overall magnitude of the disappearance and {Delta}m{sup 2} which controls the energy dependence.
123152124
Preliminary measurements of shadowing at very low XBj
The ratio of cross sections for inelastic muon scattering on xenon and deuterium nuclei was measured at very low XBj (0.00002<XBj<0.25) for 0.01<Q2<60 (GeV/c)2. The data were taken at Fermilab experiment E665 with an average muon beam energy of 490 GeV incident on 1.1 meter long deuterium and xenon targets. Two largely independent analysis techniques gave statistically consistent results and show a smooth decrease in the ratio of the xenon‐to‐deuterium per–nucleon cross sections from ∼1 to ∼0.7 as XBj decreases from ∼0.1 to ∼0.003. In the XBj range 0.00002 to 0.003, the ratio remains roughly constant at ∼0.7.
118180492
Recent results on rare $b$ decays
Recent experimental results on charmless rare b decays are reviewed.
118745241
Status of Neutrino Physics Experiments
Relevant results from neutrino physics experiments since FPCP2009 with an emphasis on oscillations and the ability to measure or limit the mixing angle {theta}{sub 13}.
14433479
Search for CP violation at CLEO
Abstract Recent results from CLEO on the search for CP violation in beauty and charm meson decays are reviewed.
42580412
Identification of High Transverse-Momentum Hadrons with a Ring-Imaging Cerenkov Counter
We have constructed and operated a large aperture ring-imaging Cerenkov counter in a high transverse-momentum experiment at Fermilab. We used multistep proportional chambers with a He/TEA photosensitive gas mixture to observe approximately 3.5 photons per relativistic particle. Hadron identification is obtained with good efficiency from threshold to 250 GeV/c.
119286485
[Ne II] Observations of Gas Motions in Compact and Ultracompact H II Regions
We present high spatial and spectral resolution observations of 16 Galactic compact and ultracompact H II regions in the [Ne II] 12.8 μm fine-structure line. The small thermal width of the neon line and the high dynamic range of the maps provide an unprecedented view of the kinematics of compact and ultracompact H II regions. These observations solidify an emerging picture of the structure of ultracompact H II regions suggested in our earlier studies of G29.96–0.02 and Mon R2 IRS 1; systematic surface flows, rather than turbulence or bulk expansion, dominate the gas motions in the H II regions. The observations show that almost all of the sources have significant (5-20 km s−1) velocity gradients and that most of the sources are limb-brightened. In many cases, the velocity pattern implies tangential flow along a dense shell of ionized gas. None of the observed sources clearly fits into the categories of filled expanding spheres, expanding shells, filled blister flows, or cometary H II regions formed by rapidly moving stars. Instead, the kinematics and morphologies of most of the sources lead to a picture of H II regions confined to the edges of cavities created by stellar wind ram pressure and flowing along the cavity surfaces. In sources where the radio continuum and [Ne II] morphologies agree, the majority of the ionic emission is blueshifted relative to nearby molecular gas. This is consistent with sources lying on the near side of their natal clouds being less affected by extinction and with gas motions being predominantly outward, as is expected for pressure-driven flows.
38395512
Atomic Carbon Is a Temperature Probe in Dark Clouds
We have mapped the C I 3P1 ? 3P0 line at 492 GHz in three molecular clouds immersed in weak ultraviolet radiation fields, TMC-1, L134N, and IC 5146. In all three clouds, the C I peak T ~ 1 K, with very small dispersion. The spatial C I distribution is extended and rather smooth. The J = 2 ? 1 transitions of CO isotopomers were observed at the same angular resolution as C I. The C I peak T is typically one-third of the peak T of 13CO J = 2 ? 1, and the C I emission is usually more extended than emission in 13CO or C18O J = 2 ? 1. The C I line width is close to the 13CO J = 2 ? 1 line width, larger than the C18O J = 2 ? 1 line width and smaller than the 12CO J = 2 ? 1 line width. The shapes of these lines occasionally differ significantly, probably because of the combined effects of differing opacities and the physical separation of the line-forming regions. The uniformity of the C I peak T is remarkable for a line in the Wien portion of the Planck function and indicates a very uniform excitation temperature. This uniformity is best explained if the line is opaque and thermalized. If so, the C I line probes kinetic temperature in clouds exposed to low-ultraviolet fluxes. This conclusion has significant implications for the thermal balance in such clouds. At AV 2, these clouds have a remarkably constant temperature from place to place and from cloud to cloud (7.9 ? 0.8 K). Photodissociation region models of clouds immersed in the mean interstellar radiation field tend to predict stronger lines than we see, but this may be an artifact of assumptions about the temperature.
119491777
H2 Pure Rotational Lines in the Orion Bar
Photodissociation regions (PDRs), where UV radiation dominates the energetics and chemistry of the neutral gas, contain most of the mass in the dense interstellar medium of our Galaxy. Observations of H2 rotational and rovibrational lines reveal that PDRs contain unexpectedly large amounts of very warm (400-700 K) molecular gas. Theoretical models have difficulty explaining the existence of so much warm gas. Possible problems include errors in the heating and cooling functions or in the formation rate for H2. To date, observations of H2 rotational lines smear out the structure of the PDR. Only by resolving the hottest layers of H2 can one test the predictions and assumptions of current models. Using the Texas Echelon Cross Echelle Spectrograph (TEXES) we mapped emission in the H2 v = 0-0 S(1) and S(2) lines toward the Orion Bar PDR at 2'' resolution. We also observed H2 v = 0-0 S(4) at selected points toward the front of the PDR. Our maps cover a 12'' by 40'' region of the bar where H2 rovibrational lines are bright. The distributions of H2 0-0 S(1), 0-0 S(2), and 1-0 S(1) line emission agree in remarkable detail. The high spatial resolution (0.002 pc) of our observations allows us to probe the distribution of warm gas in the Orion Bar to a distance approaching the scale length for FUV photon absorption. We use these new observational results to set parameters for the PDR models described in a companion paper in preparation by Draine et al. The best-fit model can account for the separation of the H2 emission from the ionization front and the intensities of the ground-state rotational lines, as well as the 1-0 S(1) and 2-1 S(1) lines. This model requires significant adjustments to the commonly used values for the dust UV attenuation cross section and the photoelectric heating rate.
14106363
W51 IRS 2: A Massive Jet Emerging from a Molecular Cloud into an H II Region
We have mapped [Ne II] (12.8 μm) and [S IV] (10.5 μm) emission from W51 IRS 2 with TEXES on Gemini North, and we compare these data to VLA free-free observations and VLT near-infrared images. With 0.5'' spatial and 4 km s-1 spectral resolution, we are able to separate the ionized gas into several components: an extended H II region on the front surface of the molecular cloud, several embedded compact H II regions, and a streamer of high-velocity gas. We interpret the high-velocity streamer as a precessing or fanlike jet, which has emerged from the molecular cloud into an OB star cluster where it is being ionized.
15000344
Starspot-Induced Radial Velocity Variability in LkCa 19
We describe a new radial velocity survey of T Tauri stars and present the first results. Our search is motivated by an interest in detecting massive young planets, as well as investigating the origin of the brown dwarf desert. As part of this survey, we discovered large-amplitude, periodic, radial velocity variations in the spectrum of the weak-line T Tauri star LkCa 19. Using line bisector analysis and a new simulation of the effect of starspots on the photometric and radial velocity variability of T Tauri stars, we show that our measured radial velocities for LkCa 19 are fully consistent with variations caused by the presence of large starspots on this rapidly rotating young star. These results illustrate the level of activity-induced radial velocity noise associated with at least some very young stars. This activity-induced noise will set lower limits on the mass of a companion detectable around LkCa 19 and similarly active young stars.