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Measurement of Inclusive Eta Production in e/sup +/e/sup -/ Interactions Near Charm Threshold

Description: The inclusive cross section for eta production in e/sup +/e/sup -/ interactions near charm threshold was measured by use of the Crystal Ball detector at SPEAR. By comparison of the inclusive eta production above and below charm threshold the following limits were obtained: R(e/sup +/e/sup -/ ..-->.. F anti FX)BR(F ..-->.. eta x) < 0.3 (90% C.L., E/sub cm/ < 4.5 GeV); BR(D ..-->.. eta x) < 0.13 (90% C.L., averaged over charged and neutral D components of the psi''). 4 figures, 1 table.
Date: August 1, 1980
Creator: Porter, F. C.
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Partner: UNT Libraries Government Documents Department
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Recent results from the Crystal Ball

Description: During the past year, the Crystal Ball experiment has continued the investigation of e/sup +/e/sup -/ interactions at SPEAR. In the course of the year, we have slightly more than doubled the available datasets at the J/psi (to 2.2 x 10/sup 6/ produced J/psi) and the psi' (to 1.8 x 10/sup 6/ produced psi') resonances, and have increased the data in the 5.2 to 7.4 GeV center-of-mass (E/sub c.m./) region. The present discussion is limited to recent results obtained with the J/psi and psi' datasets… more
Date: September 1, 1981
Creator: Porter, F. C.
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Partner: UNT Libraries Government Documents Department
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Recent results from SPEAR

Description: Recent results from SPEAR include measurements of Cabibbo-suppressed decay modes of the tau (Mark II), and a limit on the decay J/psi ..-->.. ..gamma.. + axion (Crystal Ball).
Date: August 1, 1981
Creator: Porter, F. C.
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Partner: UNT Libraries Government Documents Department
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Measurement of B sup 0 -- B sup 0 Mixing Using the MARK II at PEP

Description: B{sup 0}{bar B}{sup 0} mixing has been observed now by several experiments. The signature is the observation of an excess of same-sign dilepton events in datasets containing semileptonic B decays. Several years ago the MARK II published an upper limit on B{sup 0}{bar B}{sup 0} mixing at E{sub cm} = 29 GeV, using data taken at the e{sup +}e{sup {minus}} storage ring PEP. Here we report on the results of a new analysis with increased statistics, using refined methods with better sensitivity and c… more
Date: December 1, 1989
Creator: Porter, F.
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Partner: UNT Libraries Government Documents Department
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Slow Growing Volumetric Subdivision for 3D Volumetric Data

Description: In recent years subdivision methods have been successfully applied to the multi-resolution representation and compression of surface meshes. Unfortunately their use in the volumetric case has remained impractical because of the use of tensor-product generalizations that induce an excessive growth of the mesh size before sufficient number is preformed. This technical sketch presents a new subdivision technique that refines volumetric (and higher-dimensional) meshes at the same rate of surface me… more
Date: December 16, 2004
Creator: Pascucci, V.; Kahn, S.; Kelley, R.; Kilbourne, C.; Porter, F. & Wargelin, B.
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Partner: UNT Libraries Government Documents Department
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Time-resolved soft-x-ray spectroscopy of a magnetic octupole transition in nickel-like xenon, cesium, and barium ions

Description: A microcalorimeter with event mode capability for time-resolved soft-x-ray spectroscopy, and a high-resolution flat-field EUV spectrometer have been employed at the Livermore EBIT-I electron beam ion trap for observations and wavelength measurements of M1, E2, and M3 decays of long-lived levels in the Ni-like ions Xe{sup 26+}, Cs{sup 27+}, and Ba{sup 28+}. Of particular interest is the lowest excited level, 3d{sup 9}4s {sup 3}D{sub 3}, which can only decay via a magnetic octupole (M3) transitio… more
Date: November 11, 2005
Creator: Trabert, E; Beiersdorfer, P; Brown, G V; Boyce, K; Kelley, R L; Kilbourne, C A et al.
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Partner: UNT Libraries Government Documents Department
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Laboratory simulation of cometary x rays using a high-resolution microcalorimeter

Description: X-ray emission following charge exchange has been studied on the University of California Lawrence Livermore National Laboratory electron beam ion traps EBIT-I and EBIT-II using a high-resolution microcalorimeter. The measured spectra include the K-shell emission from hydrogen-like and helium-like C, N, O, and Ne needed for simulations of cometary x-ray emission. A comparison of the spectra produced in the interaction of O{sup 8+} with N{sub 2} and CH{sub 4} is presented that illustrates the de… more
Date: August 13, 2004
Creator: Beiersdorfer, P; Chen, H; Boyce, K R; Brown, G V; Kelley, R L; Kilbourne, C A et al.
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Partner: UNT Libraries Government Documents Department
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Proposal for the systematic naming of mesons and baryons

Description: Twenty years ago, the Particle Data Group adopted a systematic naming convention for baryons: the symbols N, ..delta.., ..lambda.., ..sigma.., ..xi.., and ..cap omega.. were to identify the isospin and strangeness, The mesons, by contrast, have become an alphabet soup of uninformative names - theta, iota, xi, zeta, g/sub T/, g/sub s/, H, E, delta, h, g, r, kappa, etc. -, and in some cases identical names are used for mesons with different quantum numbers (A, B, and D). Furthermore, experimental… more
Date: October 1, 1984
Creator: Porter, F. C.; Hernandez, J. J.; Montanet, L.; Roos, M.; Toernqvist, N. A.; Barnett, R. M. et al.
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Partner: UNT Libraries Government Documents Department
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Finding a rational nomenclature for mesons and baryons

Description: A history of the Particle Data Group's efforts to find a rational and systematic convention for naming mesons and baryons is given. Several versions of our proposal are reviewed, and name changes which would occur are summarized. Some of the mail we have received is described. We hope to stimulate additional feedback.
Date: May 1, 1985
Creator: Barnett, R. M.; Cahn, R. N.; Gidal, G.; Rittenberg, A.; Trippe, T. G.; Wohl, C. G. et al.
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Partner: UNT Libraries Government Documents Department
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Particle detection using superfluid helium

Description: We have observed 5 MeV {alpha} particles stopped in volumes-up to two liters of liquid helium at 70 mK. A fraction of the kinetic energy of an {alpha} particle is converted to elementary excitations (rotons and phonons), which progagate ballistically in isotopically pure {sup 4}He below 0.1 K. Most of these excitations have sufficient energy to evaporate helium atoms on hitting a free surface. The evaporated helium atoms can be detected calorimetrically when adsorbed on a thin silicon wafer ({a… more
Date: January 1, 1991
Creator: Bandler, S. R.; Lanou, R. E.; Maris, H. J.; More, T.; Porter, F. S.; Seidel, G. M. et al.
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Partner: UNT Libraries Government Documents Department
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Particle detection using superfluid helium

Description: We have observed 5 MeV {alpha} particles stopped in volumes-up to two liters of liquid helium at 70 mK. A fraction of the kinetic energy of an {alpha} particle is converted to elementary excitations (rotons and phonons), which progagate ballistically in isotopically pure {sup 4}He below 0.1 K. Most of these excitations have sufficient energy to evaporate helium atoms on hitting a free surface. The evaporated helium atoms can be detected calorimetrically when adsorbed on a thin silicon wafer ({a… more
Date: December 31, 1991
Creator: Bandler, S. R.; Lanou, R. E.; Maris, H. J.; More, T.; Porter, F. S.; Seidel, G. M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Laboratory Measurements of 3 -> 2 X-ray Emission Lines of Ne-like Ni

Description: The intensity ratios between 3 {yields} 2 emission lines in Ni XIX were measured on the Livermore electron beam ion trap (EBIT-I) with a flat-field grating spectrometer and the NASA/GSFC X-ray microcalorimeter. The results are consistent with earlier measurements of Fe XVII and other Ne-like ions at Livermore, and confirm the problems in the atomic modeling of the direct collisional excitation for Ne-like systems.
Date: March 18, 2004
Creator: Gu, M F; Beiersdorfer, P; Brown, G V; Chen, H; Boyce, K R; Kelley, R L et al.
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Partner: UNT Libraries Government Documents Department
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Excitation Cross Section Measurement for n=3 to n=2 Line Emission in Fe{sup 20+} to Fe{sup 23+}

Description: Electron impact excitation cross sections have been measured for iron L-shell 3 {yields} 2 lines of FeXXI to FeXXIV at the EBIT-II electron beam ion trap using a crystal spectrometer and a 6 x 6-element array microcalorimeter. The cross sections were determined by direct normalization to the well established cross section of radiative electron capture and a summary of calculated energy dependent radiative recombination cross sections for electron capture into the ground state fine structure lev… more
Date: August 25, 2004
Creator: Chen, H; Beiersdorfer, P; Scofield, J; Brown, G; Boyce, K; Kelley, R L et al.
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Partner: UNT Libraries Government Documents Department
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Electron Impact Excitation Cross Section Measurement for n=3 to n=2 Line Emission in Fe17+ to Fe23+

Description: We have measured the electron impact excitation cross sections for the strong iron L-shell 3 {yields} 2 lines of Fe XVIII to Fe XXIV at the EBIT-I electron beam ion trap using a crystal spectrometer and NASA-Goddard Space Flight Centers 6 x 6 pixel array microcalorimeter. The cross sections were determined by direct normalization to the well established cross section of radiative electron capture through a sophisticated model analysis which results in the excitation cross section for the strong… more
Date: April 20, 2006
Creator: Chen, H; Beiersdorfer, P; Brown, G V; Scofield, J; Gu, M F; Kahn, S M et al.
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Partner: UNT Libraries Government Documents Department
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The Astro-E2 XRS/EBIT Microcalorimeter XC-ray Spectrometer

Description: The X-ray Spectrometer (XRS) instrument is a revolutionary non-dispersive spectrometer that will form the basis for the Astro-E2 observatory to be launched in 2005. We have recently installed a flight spare XRS microcalorimeter spectrometer at the EBIT-I and SuperEBIT facility at LLNL replacing the XRS from the earlier Astro-E mission and providing twice the resolving power. The XRS microcalorimeter is an x-ray detector that senses the heat deposited by the incident photon. It achieves a high e… more
Date: April 16, 2004
Creator: Porter, F S; Brown, G V; Boyce, K R; Kelley, R L; Kilbourne, C A; Beiersdorfer, P et al.
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Partner: UNT Libraries Government Documents Department
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The EBIT Calorimeter Spectrometer: a new, permanent user facility at the LLNL EBIT

Description: The EBIT Calorimeter Spectrometer (ECS) is currently being completed and will be installed at the EBIT facility at the Lawrence Livermore National Laboratory in October 2007. The ECS will replace the smaller XRS/EBIT microcalorimeter spectrometer that has been in almost continuous operation since 2000. The XRS/EBIT was based on a spare laboratory cryostat and an engineering model detector system from the Suzaku/XRS observatory program. The new ECS spectrometer was built to be a low maintenance,… more
Date: September 7, 2007
Creator: Porter, F. S.; Beiersdorfer, P.; Brown, G. V.; Doriese, W.; Gygax, J.; Kelley, R. L. et al.
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Partner: UNT Libraries Government Documents Department
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Energy-dependent excitation cross section measurements of the diagnostic lines of Fe XVII

Description: By implementing a large-area, gain-stabilized microcalorimeter array on an electron beam ion trap, the electron-impact excitation cross sections for the dominant x-ray lines in the Fe XVII spectrum have been measured as a function of electron energy up to greater than three times the threshold energy, establishing a benchmark for atomic calculations. The results reveal a consistent overestimation by recent calculations of the excitation cross section of the resonance transition, which is shown … more
Date: January 24, 2005
Creator: Brown, G V; Beiersdorfer, P; Chen, H; Scofield, J H; Boyce, K R; Kelley, R L et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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