Molecular gas freeze-out in the pre-stellar core L1689B

C17O (J=2-1) observations have been carried out towards the pre-stellar core L1689B. By comparing the relative strengths of the hyperfine components of this line, the emission is shown to be optically thin. This allows accurate CO column densities to be determined and, for reference, this calculation is described in detail. The hydrogen column densities that these measurements imply are substantially smaller than those calculated from SCUBA dust emission data. Furthermore, the C17O column densities are approximately constant across L1689B whereas the SCUBA column densities are peaked towards the centre. The most likely explanation is that CO is depleted from the central regions of L1689B. Simple models of pre-stellar cores with an inner depleted region are compared with the results. This enables the magnitude of the CO depletion to be quantified and also allows the spatial extent of the freeze-out to be firmly established. We estimate that within about 5000 AU of the centre of L1689B, over 90% of the CO has frozen onto grains. This level of depletion can only be achieved after a duration that is at least comparable to the free-fall timescale.Comment: MNRAS letters. 5 pages, 5 figure

LoanSTAR Energy Auditing: Update and Changes

Annual savings identified by detailed LoanSTAR audits during the period January, 1989 -December, 1991 are $13.7 million with an investment cost of$46.1 million. These savings represent retrofit projects in state-owned buildings, local government-owned facilities, and independent school districts, accounting for 80%, 16%, and 4% of the investment cost, respectively. A summary of retrofit projects by type is presented and modifications to chillers and chilled water systems account for 26% of the savings and 32% of the cost, followed by lighting retrofits which account for 24% of the savings and 24% of the cost. The Governor's Energy Office has implemented changes to simplify the audit process by eliminating some calculations. Independent calculations and maintenance and operating procedures calculations are no longer required, and some retrofit projects may depend on standard paybacks to identify cost savings

New Measurement of the Cosmic-Ray Positron Fraction from 5 to 15 GeV

We present a new measurement of the cosmic-ray positron fraction at energies between 5 and 15 GeV with the balloon-borne HEAT-pbar instrument in the spring of 2000. The data presented here are compatible with our previous measurements, obtained with a different instrument. The combined data from the three HEAT flights indicate a small positron flux of non-standard origin above 5 GeV. We compare the new measurement with earlier data obtained with the HEAT-e+- instrument, during the opposite epoch of the solar cycle, and conclude that our measurements do not support predictions of charge sign dependent solar modulation of the positron abundance at 5 GeV.Comment: accepted for publication in PR

Parametric tolerance study of Trojan Horse plasma wakefield acceleration scheme

A promising scheme for plasma wakefield acceleration is the hybrid plasma acceleration mechanism, which is experimentally connected to world-wide programs at various accelerator facilities. This scheme may lead to extremely high quality electron bunches, which can be used to drive ultrabright light sources such as free electron lasers. The big challenge for plasma acceleration is to produce electron bunches with high quality in terms of low emittance, energy spread and high brightness. To overcome this challenge, the Trojan Horse scheme [1,2,3,4,5] is used for production of designer electron beams. This work explores the Trojan Horse mechanism in a parametric study by variation of the injector laser pulse by intensity a0, spot size w0 and relative spatiotemporal synchronization and alignment. These parameters define output electron witness beam parameters and its quality. This sensitivity study shows a high robustness of the scheme, which is promising for a wider key prospect of the approach, namely the development of compact plasma accelerators to produce electron beams with unprecedented emittance and brightness in order to power free-electron lasers

Foliar Fungicides in Seed Corn Production

Since 1982, we have conducted a program to determine the fungicides that may be effective for controlling foliar diseases in inbred and hybrid com. For the past seven years we have limited our research to only inbreds or sister line hybrids. In 1990, we started a cooperative program with seed companies and have conducted our research in commercial seed production fields in five greatly different years in terms of weather patterns. Thirty experiments have been established in seed production fields and 25 fields have been harvested for yield. Five experiments were abandoned because of herbicide injury interactions (2,4-D) with the fungicides, excessive Stewarts disease (a bacterial disease that can not be controlled with fungicides and was devastating), or drought

Fall 1969

Massachusetts Lawn and Turf Grass CouncilBetter Turf Through Research and Education Artificial Turf Faces Credibility Gab by Dr. Gene C. Nutter (page 1) Nitrogen Facts and Fallacies by W.H. Garman (2) DDT Opponents by Charles Wurster, Jr. (10) DDT Defenders by Charles Wurster, Jr. (11) What Type 2,4-D to Use? by J.S. Coartney and A.H. Kates (21) Irrigation Circuit Break Pinpointed in One Hour (24

Proton and Helium Spectra from the CREAM-III Flight

Primary cosmic-ray elemental spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment since 2004. The third CREAM payload (CREAM-III) flew for 29 days during the 2007-2008 Antarctic season. Energies of incident particles above 1 TeV are measured with a calorimeter. Individual elements are clearly separated with a charge resolution of ~0.12 e (in charge units) and ~0.14 e for protons and helium nuclei, respectively, using two layers of silicon charge detectors. The measured proton and helium energy spectra at the top of the atmosphere are harder than other existing measurements at a few tens of GeV. The relative abundance of protons to helium nuclei is 9.53+-0.03 for the range of 1 TeV/n to 63 TeV/n. The ratio is considerably smaller than other measurements at a few tens of GeV/n. The spectra become softer above ~20 TeV. However, our statistical uncertainties are large at these energies and more data are needed

The Energy Spectra and Relative Abundances of Electrons and Positrons in the Galactic Cosmic Radiation

Observations of cosmic-ray electrons and positrons have been made with a new balloon-borne detector, HEAT (the "High-Energy Antimatter Telescope"), first flown in 1994 May from Fort Sumner, NM. We describe the instrumental approach and the data analysis procedures, and we present results from this flight. The measurement has provided a new determination of the individual energy spectra of electrons and positrons from 5 GeV to about 50 GeV, and of the combined "all-electron" intensity (e+ + e-) up to about 100 GeV. The single power-law spectral indices for electrons and positrons are alpha = 3.09 +/- 0.08 and 3.3 +/- 0.2, respectively. We find that a contribution from primary sources to the positron intensity in this energy region, if it exists, must be quite small.Comment: latex2e file, 30 pages, 15 figures, aas2pp4.sty and epsf.tex needed. To appear in May 10, 1998 issue of Ap.

Texas LoanSTAR Monitoring and Analysis Program Progress Report

Eleven audit reports have been accepted by the review staff at Texas A&M University. These eleven reports cover 3.8 million square feet of building space and two street-lighting projects. One engineer has been employed to work in the GEMC for the purpose of assigning audits, approving screening reports and reviewing overall auditing progress