Statistical Uncertainties in Temperature Diagnostics for Hot Coronal Plasma Using the ASCA SIS

Statistical uncertainties in determining the temperatures of hot (0.5 keV to 10 keV) coronal plasmas are investigated. The statistical precision of various spectral temperature diagnostics is established by analyzing synthetic ASCA Solid-state Imaging Spectrometer (SIS) CCD spectra. The diagnostics considered are the ratio of hydrogen-like to helium-like line complexes of $Z\ge14$ elements, line-free portions of the continuum, and the entire spectrum. While fits to the entire spectrum yield the highest statistical precision, it is argued that fits to the line-free continuum are less susceptible to atomic data uncertainties but lead to a modest increase in statistical uncertainty over full spectral fits. Temperatures deduced from line ratios can have similar accuracy but only over a narrow range of temperatures. Convenient estimates of statistical accuracies for the various temperature diagnostics are provided which may be used in planning ASCA SIS observations.Comment: postscript file of 8 pages+3 figures; 4 files tarred, compressed and uuencoded. To appear in the Astrophysical Journal Letters; contents copyright 1994 American Astronomical Societ

A double junction model of irradiated silicon pixel sensors for LHC

In this paper we discuss the measurement of charge collection in irradiated silicon pixel sensors and the comparison with a detailed simulation. The simulation implements a model of radiation damage by including two defect levels with opposite charge states and trapping of charge carriers. The modeling proves that a doubly peaked electric field generated by the two defect levels is necessary to describe the data and excludes a description based on acceptor defects uniformly distributed across the sensor bulk. In addition, the dependence of trap concentrations upon fluence is established by comparing the measured and simulated profiles at several fluences and bias voltages.Comment: Talk presented at the 10th European Symposium on Semiconductor Detectors, June 12-16 2005, Wildbad Kreuth, Germany. 9 pages, 4 figure

Investigating 16O with the 15N(p,{\alpha})12C reaction

The 16O nucleus was investigated through the 15N(p,{\alpha})12C reaction at excitation energies from Ex = 12 231 to 15 700 keV using proton beams from a 5 MeV Van de Graaff accelerator at beam energies of Ep = 331 to 3800 keV. Alpha decay from resonant states in 16O was strongly observed for ten known excited states in this region. The candidate 4-alpha cluster state at Ex = 15.1 MeV was investigated particularly intensely in order to understand its particle decay channels.Comment: Submitted for Proceedings of Fourth International Workshop on State of the Art in Nuclear Cluster Physics (SOTANCP4), held from May 13 - 18, 2018 in Galveston, TX, US

Experimental study of the 11B(p,3α)γ^{11}\text{B}(p,3\alpha)\gamma reaction at Ep=0.5−2.7E_p = 0.5-2.7 MeV

Our understanding of the low-lying resonance structure in $^{12}$C remains incomplete. We have used the $^{11}\text{B}(p,3\alpha)\gamma$ reaction at proton energies of $E_p=0.5-2.7$ MeV as a selective probe of the excitation region above the $3\alpha$ threshold in $^{12}$C. Transitions to individual levels in $^{12}$C were identified by measuring the 3$\alpha$ final state with a compact array of charged-particle detectors. Previously identified transitions to narrow levels were confirmed and new transitions to broader levels were observed for the first time. Here, we report cross sections, deduce partial $\gamma$-decay widths and discuss the relative importance of direct and resonant capture mechanisms.Comment: 9 pages, 7 figures, 5 tables; added details on data analysi

The Intertwined Successional Development of the Lamb Gut Microbiota And Immune System (Poster)

Gastrointestinal tract (GIT) microbes play critical roles in host nutrition, health and immunological development. For adult ruminants, GIT-dwelling microbes provide ~70% of daily energy requirements. The GIT also houses 70 % of the animal’s immune system in the form of the Gut-associated Lymphatic Tissue (GALT), which houses 80% of all plasma cells and depends on microbial stimulation for maturation. Because nutrition and disease are two major factors in the economic sustainability of livestock production, our group set out to characterize the successional development of GIT microbiota and immune activity. Blood and GIT samples were collected from lambs immediately at birth through one-year of age, and from the dam’s vagina, mouth, and rectum at parturition. Blood samples were profiled for serum titers of IgM, IgA and IgG, while microbiota were profiled in GIT samples by 16S rRNA gene sequencing. Lamb GIT microbiota initially resembled the dam’s vaginal microbiota but following exposure to the dam, became rapidly more similar to the dam’s teat. GIT samples eventually formed stable climax communities similar to the dams around 180 days of age. This corresponded to the peak serum titers for each immunoglobin, which, aside from a peak in IgG at birth (likely colostral transfer), had gradually increased prior to this time. Immunoglobins peaked and then return to a sub peak level between 180 and 365 days. These results indicate dam vaginal microbiota have a short-lived impact on the neonatal microbiota, with the GIT microbiota going through a dynamic successional development to 180 d when immune function appears to peak

Measurements with the Chandra X-Ray Observatory's flight contamination monitor

NASA's Chandra X-ray Observatory includes a Flight Contamination Monitor (FCM), a system of 16 radioactive calibration sources mounted to the inside of the Observatory's forward contamination cover. The purpose of the FCM is to verify the ground-to-orbit transfer of the Chandra flux scale, through comparison of data acquired during the ground calibration with those obtained in orbit, immediately prior to opening the Observatory's sun-shade door. Here we report results of these measurements, which place limits on the change in mirror--detector system response and, hence, on any accumulation of molecular contamination on the mirrors' iridium-coated surfaces.Comment: 7pages,8figures,for SPIE 4012, paper 7

Position Dependence of Charge Collection in Prototype Sensors for the CMS Pixel Detector

This paper reports on the sensor R&D activity for the CMS pixel detector. Devices featuring several design and technology options have been irradiated up to a proton fluencec of 1E15 n_eq/cm**2 at the CERN PS. Afterward they were bump bonded to unirradiated readout chips and tested using high energy pions in the H2 beam line of the CERN SPS. The readout chip allows a non zero suppressed full analogue readout and therefore a good characterization of the sensors in terms of noise and charge collection properties. The position dependence of signal is presented and the differences between the two sensor options are discussed.Comment: Contribution to the IEEE-NSS Oct. 2003, Portland, OR, USA, submitted to IEEE-TNS 7 pages, 8 figures, 1 table. Revised, title change

Direct Determination of the Kinetics of Oxygen Diffusion to the Photocytes of a Bioluminescent Elaterid Larva, Measurement of Gas- and Aqueous-Phase Diffusional Barriers and Modelling of Oxygen Supply

We describe the development and use of a direct kinetic technique to determine the time taken for oxygen to diffuse from the external environment into the light-producing cells (photocytes) in the prothorax of bioluminescent larvae of Pyrearinus termitilluminans. This was achieved by measuring the time course of the pseudoflash induced through sequential anoxia followed by normoxia. We have also determined the separate times taken for this oxygen diffusion in gaseous and tissue (predominantly aqueous) phases by using helium and nitrogen as the carrier gas. Of the total time taken for diffusion, that in the gas phase required 613+/-136 ms (mean +/- s.e. m., N=5) whilst that in the aqueous phase required 1313+/-187 ms. These values imply pathlengths of diffusion in the gaseous and aqueous phases of 4.80x10(-)(3)+/-0.53x10(-)(3) and 8. 89x10(-)(5)+/-0.61x10(-)(5 )m, respectively. In addition, the pathlength of gas-phase diffusion was used to derive a parameter relating to the tortuosity of the tracheal system. These values, together with those obtained upon bioluminescent oxygen consumption, have been used to model oxygen supply to the photocyte. From these studies, it would also appear that the modulation of tracheolar fluid levels might be a significant mechanism of control of tissue oxygen levels in at least some insects