16861138
High Sensitivity, High Spectral Resolution, Mid-infrared Spectroscopy
We broadly discuss mid-infrared spectroscopy and detail our new high spectral resolution instrument, the Texas Echelon-cross-Echelle Spectrograph (TEXES).
118394652
Dust, Ice, and Gas In Time (DIGIT) Herschel program first results A full PACS-SED scan of the gas line emission in protostar DK Chamaeleontis
Aims. We aim to study the composition and energetics of the circumstellar material of DK Cha, an intermediate-mass star in transition from an 
embedded configuration to a star plus disk stage, during this pivotal stage of its evolution. 
Methods. Using the range scan mode of PACS on the Herschel Space Observatory, we obtained a spectrum of DK Cha from 55 to 210 μm as part 
of the DIGIT key program. 
Results. Almost 50 molecular and atomic lines were detected, many more than the 7 lines detected in ISO-LWS. Nearly the entire ladder of CO 
from J = 14–13 to 38–37 (E_u/k = 4080 K), water from levels as excited as J_(K−1 K+1) = 7_(07) (E_u/k = 843 K), and OH lines up to E_u/k = 290 K were 
detected. 
Conclusions. The continuum emission in our PACS SED scan matches the flux expected by a model consisting of a star, a surrounding disk of 
0.03 M_⊙, and an envelope of a similar mass, supporting the suggestion that the object is emerging from its main accretion stage. Molecular, atomic, 
and ionic emission lines in the far-infrared reveal the outflow’s influence on the envelope. The inferred hot gas may be photon-heated, but some 
emission may be caused by C-shocks in the walls of the outflow cavity.
15919539
TEXES: A Sensitive High-Resolution Grating Spectrograph for the Mid-Infrared
We discuss the design and performance of TEXES, the Texas Echelon Cross Echelle Spectrograph. TEXES is a mid-infrared (5-25 μm) spectrograph with several operating modes: high resolution, cross-dispersed with a resolving power of R =λ/δλ ≈ 100,000, 0.5% spectral coverage, and a ~15 × 8'' slit; medium resolution, long-slit with R ≈ 15,000, 0.5% coverage, and a ~15 × 45'' slit; low-resolution, long-slit with δλ ≈ 0.004 μm, 0.25 μm coverage, and a ~ 15 × 45'' slit; and source acquisition imaging with 033 pixels and a 25'' × 25'' field of view on a 3 m telescope. TEXES has been used at the McDonald Observatory 2.7 m and the NASA Infrared Telescope Facility 3 m telescopes and has proved to be both sensitive and versatile.
55470700
MEDIUM RESOLUTION SPECTRAL LIBRARY OF LATE-TYPE STELLAR TEMPLATES IN NEAR-INFRARED BAND
We present medium resolution (R = 5000 6000) spectra in the near-infrared band, 1.4 1.8 µm, for template stars in G, K, and M types observed by the echelle spectrometer, IRCS, at the SUBARU 8.2 m telescope. The identification of lines is based on the spectra of Arcturus (K2 III) in the literature. We measured the equivalent of widths and compared our results to those of Meyer et al. (1998). We conclude that our spectral resolution (R = 6000) data can investigate more accurately the properties of lines in stellar spectra. The library of the template stellar spectra in ASCII format are available for download on the World Wide Web.
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.
119448131
Low-Velocity Ionized Winds from Regions around Young O Stars
We have observed seven ultracompact H II regions in hydrogen recombination lines in the millimeter band. Toward four of these regions there is a high-velocity (FWHM 60-80 km s-1) component in the line profiles. The high-velocity gas accounts for 35%-70% of the emission measure within the beam. We compare these objects with an additional seven similar sources we have found in the literature. The broad recombination line objects (BRLOs) make up about 30% of all sources in complexes containing ultracompact H II regions. Comparison of spectral line and continuum data implies that the BRLOs coincide with sources with rising spectral indices, ≥0.4 up to 100 GHz. Both the number of BRLOs and their frequency of occurrence within H II region complexes, when coupled with their small size and large internal motions, mean that the apparent contradiction between the dynamical and the population lifetimes for BRLOs is even more severe than for ultracompact H II regions as a whole. We evaluate a number of possible models for the origin of the broad recombination line emission. The lifetime, morphology, and rising spectral index of the sources argue for photoevaporated disks as the cause for BRLOs. Existing models for such regions, however, do not account for the large amounts of ionized gas observed at supersonic velocities.
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.
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.
119540499
Low cost lead glass cherenkov detectors
Abstract We have compared the optical properties of lead glass bars of three different surface qualities. One was ground and polished in the conventional manner; the other two were in the unimproved state resulting from the extrusion or casting process. We find that the three bars exhibit similar optical characteristics. Use of such unpolished lead glass Cherenkov bars in electromagnetic shower detectors should result in considerable cost savings.
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.
29707171
Design and performance of beam test electronics for the PHENIX Multiplicity Vertex Detector
The system architecture and test results of the custom circuits and beam test system for the Multiplicity-Vertex Detector (MVD) for the PHENIX detector collaboration at the Relativistic Heavy Ion Collider (RHIC) are presented in this paper. The final detector per-channel signal processing chain will consist of a preamplifier-gain stage, a current-mode summed multiplicity discriminator, a 64-deep analog memory (simultaneous read-write), a post-memory analog correlator, and a 10-bit 5 /spl mu/s ADC. The Heap Manager provides all timing control, data buffering, and data formatting for a single 256-channel multi-chip module (MCM). Each chip set is partitioned into 32-channel sets. Beam test (16-cell deep memory) performance for the various blocks will be presented as well as the ionizing radiation damage performance of the 1.2 /spl mu/ n-well CMOS process used for preamplifier fabrication.