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Sample records for rate transition radiation

  1. Energy levels, radiative rates and electron impact excitation rates for transitions in Si III

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.

    2017-09-01

    Energy levels and radiative rates (A-values) for four types of transitions (E1, E2, M1, and M2) are reported for an astrophysically important Mg-like ion Si III, whose emission lines have been observed in a variety of plasmas. For the calculations, well-known and widely-used GRASP code has been adopted, and results are listed for transitions among the 141 levels of the 3 ℓ 3ℓ‧ and 3 ℓ 4 ℓ configurations. Experimental energies are available for only the lowest 58 levels but there is no major discrepancy with theoretical results. Similarly, the A-values and lifetimes show a satisfactory agreement with other available results, particularly for strong E1 transitions. Collision strengths are also calculated, with the DARC code, and listed for resonance transitions over a wide energy range, up to 30 Ryd. No similar results are available in the literature for comparisons. However, comparisons are made with the more important parameter, effective collision strength (Υ), for which recent R-matrix results are available for a wide range of transitions, and over a large range of temperatures. To determine Υ, resonances have been resolved in a narrow energy mesh, although these are not observed to be as important as for other ions. Unfortunately, large discrepancies in Υ values are noted for about half the transitions. The differences increase with increasing temperature and worsen as the upper level J increases. In most cases the earlier results are overestimated, by up to (almost) two orders of magnitude, and this conclusion is consistent with the one observed earlier for Be-like ions.

  2. Energy levels, radiative rates and electron impact excitation rates for transitions in C III

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, Francis P.

    2015-06-01

    We report energy levels, radiative rates (A-values) and lifetimes for the astrophysically important Be-like ion C III. For the calculations, 166 levels belonging to the n ≤ 5 configurations are considered and the GRASP (General-purpose Relativistic Atomic Structure Package) is adopted. Einstein A-coefficients are provided for all E1, E2, M1 and M2 transitions, while lifetimes are compared with available measurements as well as theoretical results, and no large discrepancies noted. Our energy levels are assessed to be accurate to better than 1 per cent for a majority of levels, and A-values to better than 20 per cent for most transitions. Collision strengths are also calculated, for which the Dirac Atomic R-matrix Code (DARC) is used. A wide energy range, up to 21 Ryd, is considered and resonances resolved in a fine energy mesh in the thresholds region. The collision strengths are subsequently averaged over a Maxwellian velocity distribution to determine effective collision strengths up to a temperature of 8.0 × 105 K, sufficient for most astrophysical applications. Our data are compared with the recent R-matrix calculations of Fernández-Menchero et al., and significant differences (up to over an order of magnitude) are noted for several transitions over the complete temperature range of the results.

  3. Energy levels and radiative rates for transitions in Mo XV

    NASA Astrophysics Data System (ADS)

    El-Sayed, F.; Attia, S. M.

    2017-07-01

    Energy levels, wavelengths, transition probabilities, oscillator strengths, line strengths, and lifetimes have been calculated for transitions among the fine-structure levels belonging to the (1s22s22p6)3s23p63d10, 3s23p63d94l, 3s23p53d104l, and 3s3p63d104l (l = s, p, d, f) configurations of the Ni-like Molybdenum, Mo XV. The results for electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions among the lowest levels of Mo XV have been reported and compared with available NIST results.

  4. Energy levels and radiative rates for transitions in Fe V, Co VI and Ni VII

    NASA Astrophysics Data System (ADS)

    Aggarwal, K. M.; Bogdanovich, P.; Keenan, F. P.; Kisielius, R.

    2017-03-01

    Energy levels, Landé g-factors and radiative lifetimes are reported for the lowest 182 levels of the 3d4, 3d34s and 3d34p configurations of Fe V, Co VI and Ni VII. Additionally, radiative rates (A-values) have been calculated for the E1, E2 and M1 transitions among these levels. The calculations have been performed in a quasi-relativistic approach (QR) with a very large configuration interaction (CI) wavefunction expansion, which has been found to be necessary for these ions. Our calculated energies for all ions are in excellent agreement with the available measurements, for most levels. Discrepancies among various calculations for the radiative rates of E1 transitions in Fe V are up to a factor of two for stronger transitions (f ≥ 0.1), and larger (over an order of magnitude) for weaker ones. The reasons for these discrepancies have been discussed and mainly are due to the differing amount of CI and methodologies adopted. However, there are no appreciable discrepancies in similar data for M1 and E2 transitions, or the g-factors for the levels of Fe V, the only ion for which comparisons are feasible.

  5. Energy levels, radiative rates, and lifetimes for transitions in W LVIII

    SciTech Connect

    Aggarwal, Kanti M. Keenan, Francis P.

    2014-11-15

    Energy levels and radiative rates are reported for transitions in Cl-like W LVIII. Configuration interaction (CI) has been included among 44 configurations (generating 4978 levels) over a wide energy range up to 363 Ryd, and the general-purpose relativistic atomic structure package (GRASP) adopted for the calculations. Since no other results of comparable complexity are available, calculations have also been performed with the flexible atomic code (FAC), which help in assessing the accuracy of our results. Energies are listed for the lowest 400 levels (with energies up to ∼98 Ryd), which mainly belong to the 3s{sup 2}3p{sup 5}, 3s3p{sup 6}, 3s{sup 2}3p{sup 4}3d, 3s{sup 2}3p{sup 3}3d{sup 2}, 3s3p{sup 4}3d{sup 2}, 3s{sup 2}3p{sup 2}3d{sup 3}, and 3p{sup 6}3d configurations, and radiative rates are provided for four types of transitions, i.e. E1, E2, M1, and M2. Our energy levels are assessed to be accurate to better than 0.5%, whereas radiative rates (and lifetimes) should be accurate to better than 20% for a majority of the strong transitions.

  6. Energy levels and radiative transition rates for Ge XXXI, As XXXII, and Se XXXIII

    SciTech Connect

    Aggarwal, Sunny Singh, J.; Jha, A.K.S.; Mohan, Man

    2014-07-15

    Fine-structure energies of the 67 levels belonging to the 1s{sup 2}, 1s 2l, 1s3l, 1s4l, 1s5l, and 1s6l configurations of Ge XXXI, As XXXII, and Se XXXIII have been calculated using the General-Purpose Relativistic Atomic Structure Package. In addition, radiative rates, oscillator strengths, transition wavelengths, and line strengths have been calculated for all electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among these levels. Lifetimes are also presented for all excited levels of these three ions. We have compared our results with the results available in the literature and the accuracy of the data is assessed. We predict new energy levels, oscillator strengths, and transition probabilities where no other theoretical or experimental results are available, which will form the basis for future experimental work.

  7. Energy levels, radiative rates, and lifetimes for transitions in W XL

    SciTech Connect

    Aggarwal, Kanti M. Keenan, Francis P.

    2014-11-15

    Energy levels and radiative rates are reported for transitions in Br-like tungsten, W XL, calculated with the general-purpose relativistic atomic structure package (GRASP). Configuration interaction (CI) has been included among 46 configurations (generating 4215 levels) over a wide energy range up to 213 Ryd. However, for conciseness results are only listed for the lowest 360 levels (with energies up to ∼43 Ryd), which mainly belong to the 4s{sup 2}4p{sup 5},4s{sup 2}4p{sup 4}4d,4s{sup 2}4p{sup 4}4f,4s4p{sup 6},4p{sup 6}4d,4s4p{sup 5}4d,4s{sup 2}4p{sup 3}4d{sup 2}, and 4s{sup 2}4p{sup 3}4d4f configurations, and provided for four types of transitions, E1, E2, M1, and M2. Comparisons are made with existing (but limited) results. However, to fully assess the accuracy of our data, analogous calculations have been performed with the flexible atomic code, including an even larger CI than in GRASP. Our energy levels are estimated to be accurate to better than 0.02 Ryd, whereas results for radiative rates (and lifetimes) should be accurate to better than 20% for a majority of the strong transitions.

  8. Radiative Rates for Forbidden Transitions in Doubly-Ionized Fe-Peak Elements

    NASA Astrophysics Data System (ADS)

    Fivet, Vanessa; Quinet, P.; Bautista, M.

    2012-05-01

    Accurate and reliable atomic data for lowly-ionized Fe-peak species (Sc, Ti, V, Cr, Mn, Fe, Co, Ni and Cu) are of paramount importance for the analysis of the high resolution astrophysical spectra currently available. The third spectra of several iron group elements have been observed in different galactic sources like Herbig-Haro objects in the Orion Nebula [1] and stars like Eta Carinae [2]. However, forbidden transitions between low-lying metastable levels of doubly-ionized iron-peak ions have been very little investigated so far and radiative rates for those lines remain sparse or inexistent. We are carrying out a systematic study of the electronic structure of doubly-ionized iron-peak elements. The magnetic dipole (M1) and electric quadrupole (E2) transition probabilities are computed using the pseudo-relativistic Hartree-Fock (HFR) code of Cowan [3] and the central Thomas-Fermi-Dirac potential approximation implemented in AUTOSTRUCTURE [4]. This multi-platform approach allows for consistency checks and intercomparison and has proven very successful in the study of the complex Fe-peak species where many different effects contribute [5]. References [1] A. Mesa-Delgado et al., MNRAS 395 (2009) 855 [2] S. Johansson et al., A&A 361 (2000) 977 [3] R.D. Cowan, The Theory of Atomic Structure and Spectra, Berkeley: Univ. California Press (1981) [4] N.R. Badnell, J. Phys. B: At. Mol. Opt. Phys. 30 (1997) 1 [5] M. Bautista et al., ApJ 718 (2010) L189

  9. Energy levels, radiative rates and electron impact excitation rates for transitions in He-like Ga XXX, Ge XXXI, As XXXII, Se XXXIII and Br XXXIV

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, Francis P.

    2013-04-01

    We report calculations of energy levels, radiative rates and electron impact excitation cross sections and rates for transitions in He-like Ga XXX, Ge XXXI, As XXXII, Se XXXIII and Br XXXIV. The grasp (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates. For determining the collision strengths, and subsequently the excitation rates, the Dirac atomic R-matrix code (darc) is used. Oscillator strengths, radiative rates and line strengths are reported for all E1, E2, M1 and M2 transitions among the lowest 49 levels of each ion. Additionally, theoretical lifetimes are provided for all 49 levels of the above five ions. Collision strengths are averaged over a Maxwellian velocity distribution and the effective collision strengths obtained listed over a wide temperature range up to 108 K. Comparisons are made with similar data obtained using the flexible atomic code (fac) to highlight the importance of resonances, included in calculations with darc, in the determination of effective collision strengths. Discrepancies between the collision strengths from darc and fac, particularly for some forbidden transitions, are also discussed. Finally, discrepancies between the present results for effective collision strengths with the darc code and earlier semi-relativistic R-matrix data are noted over a wide range of electron temperatures for many transitions in all ions.

  10. Energy levels, radiative rates and lifetimes for transitions in Br-like ions with 38 ⩽ Z ⩽ 42

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, Francis P.

    2014-12-01

    Energy levels and radiative rates for transitions in five Br-like ions (Sr IV, Y V, Zr VI, Nb VII and Mo VIII) are calculated with the general-purpose relativistic atomic structure package (grasp). Extensive configuration interaction has been included and results are presented among the lowest 31 levels of the 4s24p5, 4s24p44d and 4s4p6 configurations. Lifetimes for these levels have also been determined, although unfortunately no measurements are available with which to compare. However, recently theoretical results have been reported by Singh et al (2013 Phys. Scr. 88 035301) using the same grasp code. But their reported data for radiative rates and lifetimes cannot be reproduced and show discrepancies of up to five orders of magnitude with the present calculations.

  11. Stimulated coherent transition radiation

    SciTech Connect

    Hung-chi Lihn

    1996-03-01

    Coherent radiation emitted from a relativistic electron bunch consists of wavelengths longer than or comparable to the bunch length. The intensity of this radiation out-numbers that of its incoherent counterpart, which extends to wavelengths shorter than the bunch length, by a factor equal to the number of electrons in the bunch. In typical accelerators, this factor is about 8 to 11 orders of magnitude. The spectrum of the coherent radiation is determined by the Fourier transform of the electron bunch distribution and, therefore, contains information of the bunch distribution. Coherent transition radiation emitted from subpicosecond electron bunches at the Stanford SUNSHINE facility is observed in the far-infrared regime through a room-temperature pyroelectric bolometer and characterized through the electron bunch-length study. To measure the bunch length, a new frequency-resolved subpicosecond bunch-length measuring system is developed. This system uses a far-infrared Michelson interferometer to measure the spectrum of coherent transition radiation through optical autocorrelation with resolution far better than existing time-resolved methods. Hence, the radiation spectrum and the bunch length are deduced from the autocorrelation measurement. To study the stimulation of coherent transition radiation, a special cavity named BRAICER is invented. Far-infrared light pulses of coherent transition radiation emitted from electron bunches are delayed and circulated in the cavity to coincide with subsequent incoming electron bunches. This coincidence of light pulses with electron bunches enables the light to do work on electrons, and thus stimulates more radiated energy. The possibilities of extending the bunch-length measuring system to measure the three-dimensional bunch distribution and making the BRAICER cavity a broadband, high-intensity, coherent, far-infrared light source are also discussed.

  12. Radiative rates for forbidden M1 and E2 transitions of astrophysical interest in doubly ionized iron-peak elements

    NASA Astrophysics Data System (ADS)

    Fivet, V.; Quinet, P.; Bautista, M. A.

    2016-01-01

    Aims: Accurate and reliable atomic data for lowly ionized Fe-peak species (Sc, Ti, V, Cr, Mn, Fe, Co, and Ni) are of paramount importance for analyzing the high-resolution astrophysical spectra currently available. The third spectra of several iron group elements have been observed in different galactic sources, such as Herbig-Haro objects in the Orion Nebula and stars like Eta Carinae. However, forbidden M1 and E2 transitions between low-lying metastable levels of doubly charged iron-peak ions have been investigated very little so far, and radiative rates for those lines remain sparse or nonexistent. We attempt to fill that gap and provide transition probabilities for the most important forbidden lines of all doubly ionized iron-peak elements. Methods: We carried out a systematic study of the electronic structure of doubly ionized Fe-peak species. The magnetic dipole (M1) and electric quadrupole (E2) transition probabilities were computed using the pseudo-relativistic Hartree-Fock (HFR) code of Cowan and the central Thomas-Fermi-Dirac-Amaldi potential approximation implemented in AUTOSTRUCTURE. This multiplatform approach allowed for consistency checks and intercomparison and has proven very useful in many previous works for estimating the uncertainties affecting the radiative data. Results: We present transition probabilities for the M1 and E2 forbidden lines depopulating the metastable even levels belonging to the 3dk and 3dk-14s configurations in Sc III (k = 1), Ti III (k = 2), V III (k = 3), Cr III (k = 4), Mn III (k = 5), Fe III (k = 6), Co III (k = 7), and Ni III (k = 8).

  13. A systematic and detailed investigation of radiative rates for forbidden transitions of astrophysical interest in doubly ionized iron peak elements

    NASA Astrophysics Data System (ADS)

    Quinet, Pascal; Fivet, Vanessa; Bautista, Manuel

    2015-08-01

    The knowledge of accurate and reliable atomic data for lowly ionized iron peak elements, from scandium to copper, is of paramount importance for the analysis of the high resolution spectra currently available. The third spectra of several iron group elements have been observed in different galactic sources like Herbig-Haro objects in the Orion Nebula [1] and stars like Eta Carinae [2]. However, forbidden transitions between low-lying metastable levels of doubly ionized species have been little investigated so far and radiative rates for those lines remain sparse or inexistent.In the present contribution, we report on the recent study we have performed concerning the determination of magnetic dipole (M1) and electric quadrupole (E2) transition probabilities in those ions. For the calculations, we have extensively used the pseudo-relativistic Hartree-Fock (HFR) code of Cowan [3] and the central Thomas-Fermi-Dirac potential approximation implemented in AUTOSTRUCTURE [4]. This multi-platform approach allowed us to check the consistency and to assess the accuracy of the results obtained.[1] Mesa-Delgado A. et al., MNRAS 395, 855 (2009)[2] Johansson S. et al., A&A 361, 977 (2000)[3] Cowan R.D., The Theory of Atomic Structure and Spectra, Univ. California Press, Berkeley (1981)[4] Badnell N.R., J. Phys. B: At. Mol. Opt. Phys. 30, 1 (1997)

  14. Foam radiators for transition radiation detectors

    NASA Astrophysics Data System (ADS)

    Chernyatin, V.; Dolgoshein, B.; Gavrilenko, I.; Potekhin, M.; Romaniouk, A.; Sosnovtsev, V.

    1993-02-01

    A wide variety of foam radiators, potentially useful in the design of a transition radiation detector, the possible particle identification tool in collider experiments, have been tested in the beam. Various characteristics of these radiators are compared, and the conclusion is reached that certain brands of polyethylene foam are best suited for use in the detector. Comparison is made with a "traditional" radiator, which is a periodic structure of plastic foils.

  15. Transition radiation of multicharged ions

    SciTech Connect

    Malyshevsky, V. S. Fomin, G. V.; Ivanova, I. A.

    2016-02-15

    The problem of the transition radiation of multicharged ions at the interface between two media and in a thin plate under the charge-exchange conditions has been solved. It has been shown that the processes of pickup (or loss) of electrons by accelerated multicharged ions at the interface between two media significantly increases the yield of transition radiation.

  16. An evaluation of the rate of absorption of solar radiation in the O2(X3Sigma-g - b1Sigma-g) transition

    NASA Technical Reports Server (NTRS)

    Mlynczak, Martin G.

    1993-01-01

    The rate at which molecular oxygen absorbs radiation in the O2(X3Sigma-g - b1Sigma-g) transition is calculated using a line-by-line radiative transfer model. This rate is critical to the determination of the population of the O2(b1Sigma-g) state required for studies of the O2(b1Sigma-g - X3Sigma-g) dayglow, the O2(a1Delta-g - X3Sigma-g) dayglow, and possibly the rates of oxidation of H2 and N2O. Previous evaluations of this rate (which is sometimes called the g-factor) have significantly overestimated its value. The rate is tabulated as a function of altitude, pressure, and solar zenith angle.

  17. An evaluation of the rate of absorption of solar radiation in the O2(X3Sigma-g - b1Sigma-g) transition

    NASA Technical Reports Server (NTRS)

    Mlynczak, Martin G.

    1993-01-01

    The rate at which molecular oxygen absorbs radiation in the O2(X3Sigma-g - b1Sigma-g) transition is calculated using a line-by-line radiative transfer model. This rate is critical to the determination of the population of the O2(b1Sigma-g) state required for studies of the O2(b1Sigma-g - X3Sigma-g) dayglow, the O2(a1Delta-g - X3Sigma-g) dayglow, and possibly the rates of oxidation of H2 and N2O. Previous evaluations of this rate (which is sometimes called the g-factor) have significantly overestimated its value. The rate is tabulated as a function of altitude, pressure, and solar zenith angle.

  18. Atmospheric radiation flight dose rates

    NASA Astrophysics Data System (ADS)

    Tobiska, W. K.

    2015-12-01

    Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. Of the domains that are affected by space weather, the coupling between the solar and galactic high-energy particles, the magnetosphere, and atmospheric regions can significantly affect humans and our technology as a result of radiation exposure. Space Environment Technologies (SET) has been conducting space weather observations of the atmospheric radiation environment at aviation altitudes that will eventually be transitioned into air traffic management operations. The Automated Radiation Measurements for Aerospace Safety (ARMAS) system and Upper-atmospheric Space and Earth Weather eXperiment (USEWX) both are providing dose rate measurements. Both activities are under the ARMAS goal of providing the "weather" of the radiation environment to improve aircraft crew and passenger safety. Over 5-dozen ARMAS and USEWX flights have successfully demonstrated the operation of a micro dosimeter on commercial aviation altitude aircraft that captures the real-time radiation environment resulting from Galactic Cosmic Rays and Solar Energetic Particles. The real-time radiation exposure is computed as an effective dose rate (body-averaged over the radiative-sensitive organs and tissues in units of microsieverts per hour); total ionizing dose is captured on the aircraft, downlinked in real-time, processed on the ground into effective dose rates, compared with NASA's Langley Research Center (LaRC) most recent Nowcast of Atmospheric Ionizing Radiation System (NAIRAS) global radiation climatology model runs, and then made available to end users via the web and smart phone apps. Flight altitudes now exceed 60,000 ft. and extend above commercial aviation altitudes into the stratosphere. In this presentation we describe recent ARMAS and USEWX results.

  19. Energy levels and radiative rates for transitions in B-like to F-like Kr ions (Kr XXXII-XXVIII)

    SciTech Connect

    Aggarwal, K.M. Keenan, F.P.; Lawson, K.D.

    2008-05-15

    Energy levels, radiative rates, oscillator strengths, line strengths, and lifetimes have been calculated for transitions in B-like to F-like Kr ions, Kr XXXIII-XXVIII. For the calculations, the fully relativistic GRASP code has been adopted, and results are reported for all electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions among the lowest 125, 236, 272, 226, and 113 levels of Kr XXXII, Kr XXXI, Kr XXX, Kr XXIX, and Kr XXVIII, respectively, belonging to the n {<=} 3 configurations. Comparisons are made with earlier available theoretical and experimental results, and some discrepancies have been noted and explained.

  20. Measurements of radiative-decay rates of the 2s22p(2P°)-2s2p2(4P) intersystem transitions of C+

    NASA Astrophysics Data System (ADS)

    Fang, Z.; Kwong, Victor H. S.; Wang, Jiebing; Parkinson, W. H.

    1993-08-01

    The radiative-decay rates of the 2s22p(2P0)-2s2p2(4P) intersystem transitions of C+ ions have been measured by recording the time dependence of the ~233-nm emission. A cylindrical radio-frequency ion trap was used to store electron-impact-produced C+ ions. The time-dependent signals were analyzed by multiexponential least-squares fits to the data. The measured radiative-decay rates to the ground term are 146.4(+8.3,-9.2) s-1 for 4P1/2, 11.6(+0.8,-1.7) s-1 for 4P3/2, and 51.2(+2.6,-3.5) s-1 for 4P5/2. Comparison of the measured values with theoretical values is presented.

  1. Radiative rates for E1, E2, M1, and M2 transitions in Br-like ions with 43 ≤ Z ≤ 50

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, Francis P.

    2016-01-01

    Energies and lifetimes are reported for the eight Br-like ions with 43 ≤ Z ≤ 50, namely Tc IX, Ru X, Rh XI, Pd XII, Ag XIII, Cd XIV, In XV, and Sn XVI. Results are listed for the lowest 375 levels, which mostly belong to the 4s24p5, 4s24p44ℓ, 4s4p6,4s24p45ℓ, 4s24p34d2, 4s4p54ℓ, and 4s4p55ℓ configurations. Extensive configuration interaction among 39 configurations (generating 3990 levels) has been considered and the general-purpose relativistic atomic structure package (GRASP) has been adopted for the calculations. Radiative rates are listed for all E1, E2, M1, and M2 transitions involving the lowest 375 levels. Previous experimental and theoretical energies are available for only a few levels of three, namely Ru X, Rh XI and Pd XII. Differences with the measured energies are up to 4% but the present results are an improvement (by up to 0.3 Ryd) in comparison to other recently reported theoretical data. Similarly for radiative rates and lifetimes, prior results are limited to those involving only 31 levels of the 4s24p5, 4s24p44d, and 4s4p6 configurations for the last four ions. Moreover, there are generally no discrepancies with our results, although the larger calculations reported here differ by up to two orders of magnitude for a few transitions.

  2. Radiative heating rates during AAOE and AASE

    NASA Astrophysics Data System (ADS)

    Rosenfield, Joan E.

    Radiative transit computations of heating rates utilizing data from the 1987 Airborne Antarctic Ozone Experiment (AAOE) (Tuck et al., 1989) and the 1989 Airborne Arctic Stratospheric Experiment (AASE) (Turco et al., 1990) are described. Observed temperature and ozone profiles and a radiative transfer model are used to compute the heating rates for the Southern Hemisphere during AAOE and the Northern Hemisphere during AASE. The AASE average cooling rates computed inside the vortex are in good agreement with the diabatic cooling rates estimated from the ER-2 profile data for N2O for the AASE period (Schoeberl et al., 1989).

  3. Radiation rate meter development

    SciTech Connect

    Thacker, L.H.

    1989-01-01

    We are still in a very preliminary stage of examining the potentials of a new series of instruments which may be inexpensive and versatile enough to complement, or conceivably even replace, electroscope dosimeters in Civil Defense and other situations requiring radiation monitoring by the general public. These instruments were developed to provide a qualitative signal so simple to interpret that anyone can tell immediately whether they are in a dangerous radiation field, and whether they are moving into a hotter area or a cooler area. A second goal in the development has been to produce the simplest possible device at minimum cost, without compromise in effectiveness. In the simplest implementation the device is essentially a very inexpensive version of the much older Personal Radiation Monitor (PRM).

  4. Radiative Transitions in Charmonium from Lattice QCD

    SciTech Connect

    Jozef Dudek; Robert Edwards; David Richards

    2006-01-17

    Radiative transitions between charmonium states offer an insight into the internal structure of heavy-quark bound states within QCD. We compute, for the first time within lattice QCD, the transition form-factors of various multipolarities between the lightest few charmonium states. In addition, we compute the experimentally unobservable, but physically interesting vector form-factors of the {eta}{sub c}, J/{psi} and {chi}{sub c0}. To this end we apply an ambitious combination of lattice techniques, computing three-point functions with heavy domain wall fermions on an anisotropic lattice within the quenched approximation. With an anisotropy {xi} = 3 at a{sub s} {approx} 0.1 fm we find a reasonable gross spectrum and a hyperfine splitting {approx}90 MeV, which compares favorably with other improved actions. In general, after extrapolation of lattice data at non-zero Q{sup 2} to the photopoint, our results agree within errors with all well measured experimental values. Furthermore, results are compared with the expectations of simple quark models where we find that many features are in agreement; beyond this we propose the possibility of constraining such models using our extracted values of physically unobservable quantities such as the J/{psi} quadrupole moment. We conclude that our methods are successful and propose to apply them to the problem of radiative transitions involving hybrid mesons, with the eventual goal of predicting hybrid meson photoproduction rates at the GlueX experiment.

  5. Transition undulator radiation as bright infrared sources

    SciTech Connect

    Kim, K.J.

    1995-02-01

    Undulator radiation contains, in addition to the usual component with narrow spectral features, a broad-band component in the low frequency region emitted in the near forward direction, peaked at an angle 1/{gamma}, where {gamma} is the relativistic factor. This component is referred to as the transition undulator radiation, as it is caused by the sudden change in the electron`s longitudinal velocity as it enters and leaves the undulator. The characteristic of the transition undulator radiation are analyzed and compared with the infrared radiation from the usual undulator harmonics and from bending magnets.

  6. Transition radiation from relativistic electrons in periodic radiators

    NASA Technical Reports Server (NTRS)

    Cherry, M. L.; Mueller, D.; Prince, T. A.; Hartmann, G.

    1974-01-01

    The generation and detection of transition radiation have been studied in a series of experiments with electrons from 1 to 15 GeV at SLAC and at the Cornell Synchrotron. Periodic radiators, consisting of thin plastic foils stretched in air at constant spacings, were used, and proportional chambers filled with krypton or xenon served as detectors. A detailed discussion of the theoretical predictions is given, and the measurements are systematically compared with the predictions by varying the most critical parameters, such as configuration of radiators and detectors, and energy of the electrons. In general, good agreement between theory and experiment has been found. On the basis of these results, the criteria are summarized under which transition radiation can readily be observed.

  7. Effects of new rate constants of transitions from vibrational levels on non-LTE radiation in ro-vibrational bands used for H2O retrieval in the middle atmosphere

    NASA Astrophysics Data System (ADS)

    Manuilova, Rada; Kutepov, Alexander; Feofilov, Artem; Yankovsky, Valentine A.

    In this work, we investigate the sensitivity of the H _{2}O vibrational level populations and ro-vibrational spectra in the mesosphere and lower thermosphere (MLT) to new values of rate constants for the collision-induced transitions from the upper vibrational levels of H _{2}O molecule. This study contributes to the development of the H _{2}O non-equilibrium radiation model used for water vapor altitude distribution retrieval from the MLT radiation measurements. Our model accounts for 13 excited vibrational states up to energies 7445 cm-1 (the upper levels are 002, 101, 200) [Feofilov et al., 2009]. The model takes into account 54 vibrational-translational (V-T) and vibrational-vibrational (V-V) energy exchange processes at collisions of H _{2}O with N _{2}, O _{2} and O. The 32 ro-vibrational transitions forming 1.4, 1.9, 2.7, 3.2, 4.7 and 6.3 mum water vapor radiation bands are considered. Currently, the rate constants of intermolecular transitions between vibrational levels at collisions with N _{2} and O _{2} are known only for the transitions (010-000) and (001,100-020). In our model of H _{2}O vibrational level kinetics [Feofilov et al., 2009], we assumed that for all collisional transitions, at which the bending mode quantum number, v _{2}, increases by 2: H _{2}O(v _{1},v _{2},v _{3}) + M = H _{2}O(v _{1}-1,v _{2}+2,v _{3}) + M H _{2}O(v _{1},v _{2},v _{3}) + M = H _{2}O(v _{1},v _{2}+2,v _{3}-1) + M (1) the rate constants are equal to that of the process H _{2}O(001, 100) + M = H _{2}O(020) + M. Based on the analysis of currently available experimental and theoretical data, we have updated k, the rate constant of transitions (002, 101) -> 021 and (101, 200) -> 120, and estimated the effect of a new rate on the H _{2}O vibrational levels populations and limb radiation spectra. The “upper limit” of the effect was estimated using the same rate constant k for all processes of type (1), excluding process (001, 100) -> 020. The H _{2}O vibrational levels

  8. Radiative transitions in metallic nanoclusters

    NASA Astrophysics Data System (ADS)

    Shalin, A. S.

    2008-02-01

    In this article, a new theoretical approach to studying light-scattering characteristics of nanosized objects based on the solution to the Thomas-Fermi equation and quasi-classical approximation is considered. It is shown that the distribution of valence electrons in the volume of metallic clusters exhibits a specific structure of "spatial zones." With the aid of quasi-classical wave functions, expressions for the appropriate dipole moments of the transitions between the ground and excited states are obtained; the behavior of the spectrum of gold clusters depending on their sizes is studied; a comparison with existing experimental data is carried out.

  9. H- - H Collision Induced Radiative Transitions

    NASA Astrophysics Data System (ADS)

    Dadonova, A. V.; Devdariani, A. Z.

    2012-12-01

    Exchange interaction leads to the formation of gerade and ungerade states of temporary molecules (quasimolecules) formed during the H- +H slow collisions. The work deals with the radiation produced by optical transitions between those states. The main characteristics involved in the description of optical transitions in quasimolecules, i.e., energy terms, an optical dipole transition moments, have been calculated in the frame of zero-range potentials model. The main feature of calculations is that the results can be expressed analytically in closed forms via the Lambert W function.

  10. Charmonium meson and hybrid radiative transitions

    SciTech Connect

    Guo, Peng; Yépez-Martínez, Tochtli; Szczepaniak, Adam P.

    2014-06-01

    We consider the non-relativistic limit of the QCD Hamiltonian in the Coulomb gauge, to describe radiative transitions between conventional charmonium states and from the lowest multiplet of cc¯ hybrids to charmonium mesons. The results are compared to potential quark models and lattices calculations.

  11. Energy, fine structure, hyperfine structure, and radiative transition rates of the high-lying multi-excited states for B-like neon

    NASA Astrophysics Data System (ADS)

    Zhang, Chun Mei; Chen, Chao; Sun, Yan; Gou, Bing Cong; Shao, Bin

    2015-04-01

    The Rayleigh-Ritz variational method with multiconfiguration interaction wave functions is used to obtain the energies of high-lying multi-excited quartet states 1 s 22 s2 pnl and 1 s 22 p 2 nl 4Pe,o ( n ≥ 2) in B-like neon, including the mass polarization and relativistic corrections. The fine structure and hyperfine structure of the excited quartet states for this system are investigated. Configuration structures of the high-lying multi-excited series are further identified by relativistic corrections and fine structure splittings. The transition rates and wavelengths are also calculated. Calculated wavelengths include the quantum electrodynamic effects. The results are compared with other theoretical and experimental data in the literature.

  12. Coherent Transition and Smith Purcell Radiation Experiments

    SciTech Connect

    Marsh, Roark A.; Kesar, Amit S.; Temkin, Richard J.

    2006-11-27

    We review results from radiation experiments done at MIT on the Haimson Research Corporation (HRC) 17 GHz linear accelerator. Both Smith-Purcell radiation (SPR), and Coherent Transition radiation (CTR) were observed. To understand SPR, an Electric Field Integral Equation (EFIE) method was developed and confirmed with an experiment. Because our linac produces a train of bunches, radiation was only observed at integer multiples of the RF frequency. New measurements made on CTR show excellent agreement with EFIE expectations, on an absolute scale, and also provide a bunch length measurement. The possibility for an absolute scale bunch length measurement is confirmed with a proof of principle experiment. Future extension of the EFIE code and corollary experiments are discussed.

  13. Investigation of EO transition rates

    NASA Astrophysics Data System (ADS)

    Colvin, G. G.; Schreckenbach, K.

    1985-01-01

    Basic ideas on the nature of electric monopole transitions and their experimental realisation are presented. Some feeling for the sensitivity obtainable for X=B(EO)/B(E2) ratios are discussed. Examples of measurements performed using the electron spectrometer BILL are described to demonstrate their relevance in testing nuclei models. These include even-even and odd-even nuclei such as nuclei close to Z=50, rare-earth nuclei, Pt-Os isotopes and the actinides.

  14. Radiative lifetimes and transition probabilities for electric-dipole delta n equals zero transitions in highly stripped sulfur ions

    NASA Technical Reports Server (NTRS)

    Pegg, D. J.; Elston, S. B.; Griffin, P. M.; Forester, J. P.; Thoe, R. S.; Peterson, R. S.; Sellin, I. A.; Hayden, H. C.

    1976-01-01

    The beam-foil time-of-flight method has been used to investigate radiative lifetimes and transition rates involving allowed intrashell transitions within the L shell of highly ionized sulfur. The results for these transitions, which can be particularly correlation-sensitive, are compared with current calculations based upon multiconfigurational models.

  15. The use of radiative transition rates to study the changes in the excitation of Cu ions in a Ne glow discharge caused by small additions of H2, O2 and N2

    NASA Astrophysics Data System (ADS)

    Weiss, Z.; Steers, E. B. M.; Mushtaq, S.; Hoffmann, V.; Pickering, J. C.

    2016-04-01

    The excitation of Cu+ ions in a Ne glow discharge with small additions of H2, O2 and N2 was studied. Ratios of radiative transition rates between different Cu II levels in a discharge in neon, with and without the molecular gas added, were calculated, and the formalism of transition rate ratio (TRR) diagrams was developed and used to study the changing excitation conditions. Virtually no changes in the excitation of Cu+ ions occur in a neon discharge if nitrogen is added. Additions of hydrogen and oxygen to neon as the discharge gas affect excitation of the 4d, 5s and some other Cu II levels in the vicinity of the ionization energy of neon (21.56 eV). Also some lower Cu II levels, excited by radiative decay of those higher energy levels, are affected. The 4p 3P2 level at 15.96 eV is enhanced by additions of hydrogen. It was suggested that this enhancement is caused by the asymmetric charge transfer reaction between neutral copper atoms and the H2+ molecular ions.

  16. Transition radiation effects in superconducting granules

    NASA Technical Reports Server (NTRS)

    Drukier, A. K.; Valette, C.; Waysand, G.; Peters, F.; Yuan, L. C. L.

    1975-01-01

    The paper examines the use of a superheated superconducting suspension as a transition radiation detector of relativistic charged particles. The suspensions would also be used for detecting low-energy X-ray photons. The DESY experiment for developing such a superconducting detector has been carried out at a 7 GeV electron synchrotron. The detection is shown to be based on the recordable flipping of the state of a single superconducting grain.

  17. Transition radiation effects in superconducting granules

    NASA Technical Reports Server (NTRS)

    Drukier, A. K.; Valette, C.; Waysand, G.; Peters, F.; Yuan, L. C. L.

    1975-01-01

    The paper examines the use of a superheated superconducting suspension as a transition radiation detector of relativistic charged particles. The suspensions would also be used for detecting low-energy X-ray photons. The DESY experiment for developing such a superconducting detector has been carried out at a 7 GeV electron synchrotron. The detection is shown to be based on the recordable flipping of the state of a single superconducting grain.

  18. The rate constant for formation of HCl through radiative association

    NASA Astrophysics Data System (ADS)

    Kathir, R. K.; Nyman, Gunnar; Gustafsson, Magnus

    2017-09-01

    Formation of HCl in its electronic ground state through radiative association is studied. We ignore spin-orbit couplings and then the formation can happen through two dipole-allowed reactions, one involving an electronic transition and one where the H and Cl atoms approach and remain in the ground electronic molecular state. The radiative association rate constant is computed, through a combination of classical and quantum methods, for use in modelling of interstellar chemistry.

  19. PAMELA Space Mission: The Transition Radiation Detector

    NASA Astrophysics Data System (ADS)

    Ambriola, M.; Bellotti, R.; Cafagna, F.; Circella, M.; De Marzo, C.; Giglietto, N.; Marangelli, B.; Mirizzi, N.; Romita, M.; Spinelli, P.

    2003-07-01

    PAMELA telescope is a satellite-b orne magnetic spectrometer built to fulfill the primary scientific objectives of detecting antiparticles (antiprotons and positrons) in the cosmic rays, and to measure spectra of particles in cosmic rays. The PAMELA telescope is currently under integration and is composed of: a silicon tracker housed in a permanent magnet, a time of flight and an anticoincidence system both made of plastic scintillators, a silicon imaging calorimeter, a neutron detector and a Transition Radiation Detector (TRD). The TRD detector is composed of 9 sensitive layers of straw tubes working in proportional mode for a total of 1024 channels. Each layer is interleaved with a radiator plane made of carbon fibers. The TRD detector characteristics will be described along with its performance studied exposing the detector to particle beams of electrons, pions, muons and protons of different momenta at both CERN-PS and CERN-SPS facilities.

  20. Radiation damage of transition metal carbides

    SciTech Connect

    Dixon, G.

    1991-01-01

    In this grant period we have investigated electrical properties of transition metal carbides and radiation-induced defects produced by low-temperature electron irradiation in them. Special attention has been given to the composition VC[sub 0.88] in which the vacancies on the carbon sublattice of this fcc crystal order to produce a V[sub 8]C[sub 7] superlattice. The existence of this superlattice structure was found to make the crystal somewhat resistant to radiation damage at low doses and/or at ambient temperature. At larger doses significant changes in the resistivity are produced. Annealing effects were observed which we believe to be connected with the reconstitution of the superlattice structure.

  1. Millijoule terahertz coherent transition radiation at LEBRA

    NASA Astrophysics Data System (ADS)

    Sei, Norihiro; Ogawa, Hiroshi; Sakai, Takeshi; Hayakawa, Ken; Tanaka, Toshinari; Hayakawa, Yasushi; Nogami, Kyoko

    2017-03-01

    We developed an intense coherent transition radiation (CTR) at the Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University. A rectangular titanium screen with dimensions of 80 × 60 mm2 was used as the target, and the backward CTR generated on the screen was extracted through a crystal quartz window to air. We observed an intense terahertz (THz) radiation and confirmed it to be the CTR by measuring the spatial distribution and the dependence of the power on the electron charge. The CTR spectrum measured using a Martin–Puplett-type interferometer showed a maximum at a frequency of 0.3 THz and was emitted up to 1.6 THz. The CTR energy and peak power of a micropulse were approximately 80 nJ and 100 kW, respectively. The CTR energy during a 4.5 µs macropulse was approximately 1 mJ, indicating that this broadband THz light source is one of the most powerful coherent radiation sources in normal conducting linac facilities.

  2. On transition rates in surface hopping

    NASA Astrophysics Data System (ADS)

    Escartín, J. M.; Romaniello, P.; Stella, L.; Reinhard, P.-G.; Suraud, E.

    2012-12-01

    Trajectory surface hopping (TSH) is one of the most widely used quantum-classical algorithms for nonadiabatic molecular dynamics. Despite its empirical effectiveness and popularity, a rigorous derivation of TSH as the classical limit of a combined quantum electron-nuclear dynamics is still missing. In this work, we aim to elucidate the theoretical basis for the widely used hopping rules. Naturally, we concentrate thereby on the formal aspects of the TSH. Using a Gaussian wave packet limit, we derive the transition rates governing the hopping process at a simple avoided level crossing. In this derivation, which gives insight into the physics underlying the hopping process, some essential features of the standard TSH algorithm are retrieved, namely (i) non-zero electronic transition rate ("hopping probability") at avoided crossings; (ii) rescaling of the nuclear velocities to conserve total energy; (iii) electronic transition rates linear in the nonadiabatic coupling vectors. The well-known Landau-Zener model is then used for illustration.

  3. HIGH-ACCURACY MR-MP PERTURBATION THEORY ENERGY AND RADIATIVE RATES CALCULATIONS FOR CORE-EXCITED TRANSITIONS IN Fe XVI

    SciTech Connect

    Diaz, F.; Vilkas, M. J.; Ishikawa, Y.; Beiersdorfer, P.

    2013-07-01

    Accurate theoretical energy level, lifetime, and transition probability calculations of core-excited Fe XVI were performed employing the relativistic Multireference Moller-Plesset perturbation theory. In these computations the term energies of the highly excited n {<=} 5 states arising from the configuration 1s {sup 2}2s{sup k} 2p{sup m} 3l {sup p} nl' {sup q}, where k + m + p + q = 9, l {<=} 3 and p + q {<=} 2 are considered, including those of the autoionizing levels with a hole-state in the L-shell. All even and odd parity states of sodium-like iron ion were included for a total of 1784 levels. Comparison of the calculated L-shell transition wavelengths with those from laboratory measurements shows excellent agreement. Therefore, our calculation may be used to predict the wavelengths of as of yet unobserved Fe XVI, such as the second strongest 2p-3d Fe XVI line, which has not been directly observed in the laboratory and which blends with one of the prominent Fe XVII lines.

  4. Classical calculations of radiative association in absence of electronic transitions

    NASA Astrophysics Data System (ADS)

    Gustafsson, Magnus

    2013-02-01

    A formula for the cross section of radiative association where no electronic transitions take place is derived and tested for diatomic molecules. The approach is based on classical mechanics and therefore it is valid for direct, i.e., non-resonant, radiative association. For the formation of carbon monoxide (CO) and the cyano radical (CN), in the X1Σ+ and A1Π states, respectively, the treatment reproduces the baselines of the cross sections obtained using quantum mechanical perturbation theory. The method overestimates the formation cross section of potassium sodide (NaK) by about 8%. For the lower mass diatoms hydrogen fluoride (HF) and deuterium hydride (HD), the formula overestimates the cross sections by 12% and 60%, respectively. The formula can be used alone for estimates of radiative association rate constants, or in combination with Breit-Wigner theory to include resonance contributions.

  5. Observation of subterahertz monochromatic transition radiation from a grating

    NASA Astrophysics Data System (ADS)

    Potylitsyn, A. P.; Naumenko, G. A.; Sukhikh, L. G.; Aryshev, A.; Shevelev, M.; Terunuma, N.; Urakawa, J.

    2016-12-01

    Transition radiation appearing when a charged particle crosses the interface between two media with different dielectric constants, e.g., a metal-vacuum interface, has been well studied in a wide spectral range. However, primarily, radiation from smooth interfaces has been studied. Transition radiation from conducting gratings (grating transition radiation) is experimentally studied and theoretically analyzed in this work. In this case, it is possible to obtain monochromatic radiation with a tunable frequency depending on the rotation angle of the grating with respect to the electron momentum. Coherent grating transition radiation can be efficiently used as a source of terahertz radiation based on the use of a compact electron accelerator with an energy below 10 MeV and a bunch duration of ≤1 ps.

  6. Emission Angles for Soft X-Ray Coherent Transition Radiation.

    DTIC Science & Technology

    1987-09-01

    possible sources of error are cited. Acceso ;i For NTIS CRA&I i IC TAB L AW 4i 3 TABLE OF CONTENTS I. INTRODUCTION...addition of radiation from multiple foil stacks and the use of transition radiation as a particle beam detector [Ref. 2:p. 3594). E Use of transition...radiation to measure the energy of * electrons in early studies was restricted by the absorption of the x-rays by multiple dielectric foil stacks. The high 7

  7. Radiative heating rates near the stratospheric fountain

    NASA Technical Reports Server (NTRS)

    Doherty, G. M.; Newell, R. E.; Danielsen, E. F.

    1984-01-01

    Radiative heating rates are computed for various sets of conditions thought to be appropriate to the stratospheric fountain region: with and without a layer of cirrus cloud between 100 and 150 mbar; with standard ozone and with decreased ozone in the lower stratosphere, again with and without the cirrus cloud; and with different temperatures in the tropopause region. The presence of the cloud decreases the radiative cooling below the cloud in the upper troposphere and increases the cooling above it in the lower stratosphere. The cloud is heated at the base and cooled at the top and thus radiatively destabilized; overall it gains energy by radiation. Decreasing ozone above the cloud also tends to cool the lower stratosphere. The net effect is a tendency for vertical convergence and horizontal divergence in the cloud region. High resolution profiles of temperature, ozone, and cloudiness within the fountain region are required in order to assess the final balance of the various processes.

  8. Optical transition radiation beam emittance diagnostics

    SciTech Connect

    Fiorito, R.B.; Rule, D.W.

    1994-10-10

    We have developed several analytic and experimental techniques to measure the divergence and emittance of charged particle beams, which employ optical transition radiation (OTR) produced from thin intercepting foils. OTR`s directionality, promptness, linearity, polarization, and the sensitivity of its angular distribution to energy and divergence, can be all exploited to diagnose the spatial distribution, energy, and emittance of a charged particle beam. We describe the techniques we have developed to separately determine the {ital x} and {ital y} emittances of a beam at an {ital x} or {ital y} waist using OTR from a single foil or a two foil OTR interferometer. These methods have proven to be especially valuable for diagnosing low emittance electron beams produced by FEL accelerators, which range in energy from 17 to 110 Mev. However, we have shown that there is no inherent theoretical limit to the utility of these methods for much higher energy lepton or hadron beams. The advantages of OTR methods over those commonly used to diagnose beam properties are described.

  9. Resonance transition radiation X-ray laser

    NASA Technical Reports Server (NTRS)

    Reid, Max B.; Piestrup, Melvin A.

    1991-01-01

    A free electron laser is proposed using a periodic dielectric and helical magnetic field. Periodic synchronism between the electrons and the optical wave is obtained at the period of the dielectric and not at the period of the helical magnetic field. The synchronism condition and the gain of the new device are derived. The effects on the gain from dephasing and beam expansion due to elastic scattering of the electrons in the periodic medium are included in the gain calculation. Examples of the resonance transition radiation laser and klystron are given. Operation at photon energies between 2.5 and 3.5 keV with net gain up to 12 percent is feasible using high electron-beam energies of 3 and 5 GeV. Moderate (300-MeV) beam energy allows operation between 80 to 110 eV with up to 57 percent net gain using a klystron design. In both cases, rapid foil heating may limit operation to a single electron-beam pulse.

  10. Radiative transitions of excited ions moving slowly in plasmas

    SciTech Connect

    Hu, Hongwei Chen, Wencong; Li, Peng; Zhao, Yongtao; Zhou, Xianming; Li, Zhen; Li, Fuli; Dong, Chenzhong

    2014-12-15

    The electric dipole transitions of excited ions moving slowly in plasmas are studied. The results show that some transitions forbidden for excited ions at rest become allowed for moving excited ions. The transition rates change with varying speed of the ions. Forbidden transitions are strongly influenced by the speed, non-forbidden transitions are weakly influenced.

  11. Radiation Leukemogenesis at Low Dose Rates

    SciTech Connect

    Weil, Michael; Ullrich, Robert

    2013-09-25

    The major goals of this program were to study the efficacy of low dose rate radiation exposures for the induction of acute myeloid leukemia (AML) and to characterize the leukemias that are caused by radiation exposures at low dose rate. An irradiator facility was designed and constructed that allows large numbers of mice to be irradiated at low dose rates for protracted periods (up to their life span). To the best of our knowledge this facility is unique in the US and it was subsequently used to study radioprotectors being developed for radiological defense (PLoS One. 7(3), e33044, 2012) and is currently being used to study the role of genetic background in susceptibility to radiation-induced lung cancer. One result of the irradiation was expected; low dose rate exposures are ineffective in inducing AML. However, another result was completely unexpected; the irradiated mice had a very high incidence of hepatocellular carcinoma (HCC), approximately 50%. It was unexpected because acute exposures are ineffective in increasing HCC incidence above background. This is a potential important finding for setting exposure limits because it supports the concept of an 'inverse dose rate effect' for some tumor types. That is, for the development of some tumor types low dose rate exposures carry greater risks than acute exposures.

  12. Reaction rate constant for radiative association of CF+

    NASA Astrophysics Data System (ADS)

    Ã-ström, Jonatan; Bezrukov, Dmitry S.; Nyman, Gunnar; Gustafsson, Magnus

    2016-01-01

    Reaction rate constants and cross sections are computed for the radiative association of carbon cations (C+) and fluorine atoms (F) in their ground states. We consider reactions through the electronic transition 11Π → X1Σ+ and rovibrational transitions on the X1Σ+ and a3Π potentials. Semiclassical and classical methods are used for the direct contribution and Breit-Wigner theory for the resonance contribution. Quantum mechanical perturbation theory is used for comparison. A modified formulation of the classical method applicable to permanent dipoles of unequally charged reactants is implemented. The total rate constant is fitted to the Arrhenius-Kooij formula in five temperature intervals with a relative difference of <3%. The fit parameters will be added to the online database KIDA. For a temperature of 10-250 K, the rate constant is about 10-21 cm3 s-1, rising toward 10-16 cm3 s-1 for a temperature of 30 000 K.

  13. Transition radiation as a source of cosmic X-rays.

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Bleach, R. D.

    1972-01-01

    It is shown that transition radiation generated during the passage of relativistic charged particles through interstellar grains can be an important source of cosmic X-rays. In order to account for recent X-ray observations below 300 eV by transition radiation, an energy density in interstellar space of about 10 eV per cu cm in 10 MeV electrons is required. This seems to rule out transition radiation as an important source of diffuse cosmic X-rays in any energy region.

  14. Coherent Transition Radiation to Measure the SLAC Electron Bunch Length

    SciTech Connect

    Muggli, P.; Hogan, M.J.; Barnes, C.D.; Walz, D.; Krejcik, P.; Siemann, R.H.; /SLAC

    2005-05-13

    Coherent transition radiation is used to measure the length of the ultra-short electron bunches available at the Stanford Linear Accelerator Center. The results and the limitations of the method are described.

  15. Gravitational radiation from first-order phase transitions

    SciTech Connect

    Child, Hillary L.; Giblin, John T. Jr. E-mail: giblinj@kenyon.edu

    2012-10-01

    It is believed that first-order phase transitions at or around the GUT scale will produce high-frequency gravitational radiation. This radiation is a consequence of the collisions and coalescence of multiple bubbles during the transition. We employ high-resolution lattice simulations to numerically evolve a system of bubbles using only scalar fields, track the anisotropic stress during the process and evolve the metric perturbations associated with gravitational radiation. Although the radiation produced during the bubble collisions has previously been estimated, we find that the coalescence phase enhances this radiation even in the absence of a coupled fluid or turbulence. We comment on how these simulations scale and propose that the same enhancement should be found at the Electroweak scale; this modification should make direct detection of a first-order electroweak phase transition easier.

  16. Recent progress in the development of transition radiation detectors

    NASA Technical Reports Server (NTRS)

    Cherry, M. L.; Hartmann, G.; Prince, T.; Mueller, D.

    1978-01-01

    Transition-radiation detectors have been used in several recent cosmic-ray experiments for particle identification at energies E/mc-squared of at least about 1000. In order to optimize the design of such detectors and to use them for energy measurements over a broad energy range, it is necessary to study the details of the transition-radiation process. Experimental results are presented which test the theoretical predictions more precisely and at higher energies than in previous experiments. The dependence of the interference pattern in the frequency spectrum on the radiator dimensions is studied, and the total transition-radiation yield generated by electrons in various radiators is measured over a very wide energy range, from 5 to 300 GeV. The significance of the individual experimental parameters in the design of transition radiation detectors is reviewed, and the characteristics of transition-radiation detectors capable of measuring particle energies over the range E/mc-squared from about 300 to 100,000 are discussed.

  17. Measurements of the frequency spectrum of transition radiation

    NASA Technical Reports Server (NTRS)

    Cherry, M. L.; Mueller, D.

    1977-01-01

    We report a measurement of the frequency spectrum of X-ray transition radiation. X rays were generated by electrons of 5 and 9 GeV in radiators of multiple polypropylene foils, and detected in the range 4 to 30 keV with a calibrated single-crystal Bragg spectrometer. The experimental results closely reproduce the features of the theoretically predicted spectrum. In particular, the pronounced interference pattern of multifoil radiators and the expected hardening of the radiation with increasing foil thickness are clearly observed. The overall intensity of the radiation is somewhat lower than predicted by calculations.

  18. Measurements of the frequency spectrum of transition radiation

    NASA Technical Reports Server (NTRS)

    Cherry, M. L.; Mueller, D.

    1977-01-01

    We report a measurement of the frequency spectrum of X-ray transition radiation. X rays were generated by electrons of 5 and 9 GeV in radiators of multiple polypropylene foils, and detected in the range 4 to 30 keV with a calibrated single-crystal Bragg spectrometer. The experimental results closely reproduce the features of the theoretically predicted spectrum. In particular, the pronounced interference pattern of multifoil radiators and the expected hardening of the radiation with increasing foil thickness are clearly observed. The overall intensity of the radiation is somewhat lower than predicted by calculations.

  19. Supported transition metal nanomaterials: Nanocomposites synthesized by ionizing radiation

    NASA Astrophysics Data System (ADS)

    Clifford, D. M.; Castano, C. E.; Rojas, J. V.

    2017-03-01

    Nanostructures decorated with transition metal nanoparticles using ionizing radiation as a synthesis method in aqueous solutions represents a clean alternative to existing physical, chemical and physicochemical methods. Gamma irradiation of aqueous solutions generates free radicals, both oxidizing and reducing species, all distributed homogeneously. The presence of oxidant scavengers in situ during irradiation generates a highly reductive environment favoring the reduction of the metal precursors promoting seed formation and nanoparticle growth. Particle growth is controlled by addition of surfactants, polymers or various substrates, otherwise referred to as supports, which enhance the formation of well dispersed nanoparticles. Furthermore, the combination of nanoparticles with supports can offer desirable synergisms not solely presented by the substrate or nanoparticles. Thus, supported nanoparticles offer a huge diversity of applications. Among the ionizing radiation methods to synthesize nanomaterials and modify their characteristics, gamma irradiation is of growing interest and it has shown tremendous potential in morphological control and distribution of particle size by judiciously varying parameters including absorbed dose, dose rate, concentration of metal precursor, and stabilizing agents. In this work, major advances on the synthesis of supported nanoparticles through gamma irradiation are reviewed as well as the opportunities to develop and exploit new composites using gamma-rays and other accessible ionizing radiation sources such as X-rays.

  20. Extended range radiation dose-rate monitor

    DOEpatents

    Valentine, Kenneth H.

    1988-01-01

    An extended range dose-rate monitor is provided which utilizes the pulse pileup phenomenon that occurs in conventional counting systems to alter the dynamic response of the system to extend the dose-rate counting range. The current pulses from a solid-state detector generated by radiation events are amplified and shaped prior to applying the pulses to the input of a comparator. The comparator generates one logic pulse for each input pulse which exceeds the comparator reference threshold. These pulses are integrated and applied to a meter calibrated to indicate the measured dose-rate in response to the integrator output. A portion of the output signal from the integrator is fed back to vary the comparator reference threshold in proportion to the output count rate to extend the sensitive dynamic detection range by delaying the asymptotic approach of the integrator output toward full scale as measured by the meter.

  1. GEANT4 X-ray transition radiation package

    NASA Astrophysics Data System (ADS)

    Grichine, V. M.; Sadilov, S. S.

    2006-07-01

    Implementation of particular C++ classes in G EANT4 X-ray transition radiation (XTR) library is discussed. Recent developments concerning the transparent regular XTR radiator and XTR generated in straw tube (consisting three media) are considered in details. Simulation results are compared with experimental data.

  2. The generation of transition radiation by relativistic particles in plastic foam radiators

    NASA Technical Reports Server (NTRS)

    Prince, T. A.; Mueller, D.; Cherry, M. L.; Hartmann, G.

    1975-01-01

    The design of large area transition radiation detectors for highly relativistic particles can be greatly simplified if plastic foam radiators are employed. Using electron beams with energies 1-9 GeV at the Cornell synchrotron, we have studied the properties of a large variety of transition radiators consisting of commercially available foam materials. In most cases, a measurable transition radiation signal has been observed, but only a few materials have been found to be suitable for practical purposes. The observed radiation yield is in these cases very similar to that of equivalent multifoil radiators. A detailed discussion is given of the particle detection efficiency that can be obtained with high yield foam radiators.

  3. Transit: Radiative-transfer code for planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Cubillos, Patricio; Blecic, Jasmina; Harrington, Joe; Rojo, Patricio; Foster, Austin J.; Stemm, Madison; Challener, Ryan; Foster, Andrew S. D.

    2017-04-01

    Transit calculates the transmission or emission spectrum of a planetary atmosphere with application to extrasolar-planet transit and eclipse observations, respectively. It computes the spectra by solving the one-dimensional line-by-line radiative-transfer equation for an atmospheric model.

  4. Influence of relaxation transitions on radiation-initiated cationic graft polymerization. [Gamma radiation

    SciTech Connect

    Kudryavtsev, V.N.; Kabanov, V.Ya.; Chalykh, A.E.; Spitsyn, V.I.

    1982-05-01

    Radiation grafting of vinyl n-butyl ether (VBE) to polyvinyl chloride (PVC) over a broad temperature range was investigated. The relaxation transitions in the PVC/VBE system were also determined. Grafting of vinyl alkyl ethers proceeds entirely by a cationic mechanism in a reaction medium that has been dried to a water concentration no greater than 0.1-1.0 ppm. In this connection, the diffusion properties of water in the temperature region were studied. Commercial films of unplasticized PVC (thickness 200 M); were subjected to swelling in two systems: in a 50% solution of VBE in benzene at 25/sup 0/C, and in the pure monomer at 40/sup 0/C. The reaction mixtures were first dried over metallic sodium in a deaerated atmosphere. The specimens were irradiated in a Co gamma-radiation unit to a dose of 10 kGy at a dose rate of 3 Gy/sec. The first reaction mixture was investigated over a range of temperatures from -60/sup 0/ to +70/sup 0/C, and the second from -15/sup 0/ to +50/sup 0/C. The degree of grafting was determined from the increase in weight of the original ungrafted film. The temperature was held to within +/-1/sup 0/C. The relaxation transitions in the swollen polymer systems were determined by two methods, thermostimulated current (TSC) and thermomechanics (TM). It was found that in the region of the glass transition of a swollen PVC-VBE system, radiation-initiated cationic graft polymerization proceeds at a maximal rate, and there are changes in state of the water molecules (the agents of breaking the ion reaction chain) and in their diffusion properties within the matrix.

  5. Rate of thermal transitions in kagome spin ice

    NASA Astrophysics Data System (ADS)

    Liashko, S. Y.; Uzdin, V. M.; Jónsson, H.

    2016-08-01

    The rate of thermal transitions in a kagome spin ice element is calculated using harmonic transition state theory for magnetic systems. Each element consists of six prolate magnetic islands. Minimum energy paths on the multidimensional energy surface are found to estimate activation energy. Vibrational frequencies are also calculated to estimate the rate of the various transitions. An overall transition rate between equivalent ground states is calculated by using the stationary state approximation including all possible transition paths. The resulting transition rate is in a good agreement with experimentally measured lifetime.

  6. Prototype Operational Advances for Atmospheric Radiation Dose Rate Specification

    NASA Astrophysics Data System (ADS)

    Tobiska, W. K.; Bouwer, D.; Bailey, J. J.; Didkovsky, L. V.; Judge, K.; Garrett, H. B.; Atwell, W.; Gersey, B.; Wilkins, R.; Rice, D.; Schunk, R. W.; Bell, D.; Mertens, C. J.; Xu, X.; Crowley, G.; Reynolds, A.; Azeem, I.; Wiltberger, M. J.; Wiley, S.; Bacon, S.; Teets, E.; Sim, A.; Dominik, L.

    2014-12-01

    Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. The coupling between the solar and galactic high-energy particles, the magnetosphere, and atmospheric regions can significantly affect humans and our technology as a result of radiation exposure. Space Environment Technologies (SET) has developed innovative, new space weather observations that will become part of the toolset that is transitioned into operational use. One prototype operational system for providing timely information about the effects of space weather is SET's Automated Radiation Measurements for Aerospace Safety (ARMAS) system. ARMAS will provide the "weather" of the radiation environment to improve aircraft crew and passenger safety. Through several dozen flights the ARMAS project has successfully demonstrated the operation of a micro dosimeter on commercial aviation altitude aircraft that captures the real-time radiation environment resulting from Galactic Cosmic Rays and Solar Energetic Particles. The real-time radiation exposure is computed as an effective dose rate (body-averaged over the radiative-sensitive organs and tissues in units of microsieverts per hour); total ionizing dose is captured on the aircraft, downlinked in real-time via Iridium satellites, processed on the ground into effective dose rates, compared with NASA's Langley Research Center (LaRC) most recent Nowcast of Atmospheric Ionizing Radiation System (NAIRAS) global radiation climatology model runs, and then made available to end users via the web and smart phone apps. We are extending the dose measurement domain above commercial aviation altitudes into the stratosphere with a collaborative project organized by NASA's Armstrong Flight Research Center (AFRC) called Upper-atmospheric Space and Earth Weather eXperiment (USEWX). In USEWX we will be flying on the ER-2 high altitude aircraft a micro dosimeter for

  7. Sound radiation due to boundary layer transition

    NASA Technical Reports Server (NTRS)

    Wang, Meng

    1993-01-01

    This report describes progress made to date towards calculations of noise produced by the laminar-turbulence transition process in a low Mach number boundary layer formed on a rigid wall. The primary objectives of the study are to elucidate the physical mechanisms by which acoustic waves are generated, to clarify the roles of the fluctuating Reynolds stress and the viscous stress in the presence of a solid surface, and to determine the relative efficiency as a noise source of the various transition stages. In particular, we will examine the acoustic characteristics and directivity associated with three-dimensional instability waves, the detached high-shear layer, and turbulent spots following a laminar breakdown. Additionally, attention will be paid to the unsteady surface pressures during the transition, which provide a source of flow noise as well as a forcing function for wall vibration in both aeronautical and marine applications.

  8. Excitation rates for transitions in Ca XV

    NASA Astrophysics Data System (ADS)

    Aggarwal, K. M.; Keenan, F. P.

    2003-08-01

    Collision strengths for transitions among the energetically lowest 46 fine-structure levels belonging to the (1s2) 2s22p2, 2s2p3, 2p4, and 2s22p3l configurations of Ca XV are computed, over a wide electron energy range below 300 Ryd, using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (\\cite{Norrington03}). Resonances in the threshold region have been resolved in a fine energy mesh, and excitation rates are determined over a wide electron temperature range below 107 K. The results are compared with those available in the literature, and the accuracy of the data is assessed. Table \\ref{tab3} is also (and Table 4 only) available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/407/769

  9. Transition radiation detectors: state of art and new developments

    NASA Astrophysics Data System (ADS)

    Mazziotta, M. N.; Brigida, M.; Favuzzi, C.; Fusco, P.; Gargano, F.; Giglietto, N.; Giordano, F.; Loparco, F.; Marangelli, B.; Mirizzi, N.; Rainò, S.; Spinelli, P.

    2005-08-01

    Transition radiation (TR) is emitted whenever a fast particle (γ > 1000) crosses the boundaries of a periodic structure. Since the prediction of this effect, many studies and tests have been accomplished to understand both the features of this radiation and the eventual practical applications. Nowadays. the main application of TR is particle identification in accelerator physics and astrophysics. Particle identification is one of the most challenging aspect of the experiments performed in these fields. In fact the experimental problems arisen in the recent accelerator physics pose stringent constraints on the detectors due to the high rates, severe background conditions, event final state complexity. On the other hand, the cosmic ray physics requires in some cases simple but refined and reliable devices to be used in outer space or otherwise huge and stable apparata for surface and underground laboratories. After a brief presentation of the TR phenomenon produced by ultrarelativistic particles and relative detectors, the state of the art of this particle identification technique relative to the more recent TRDs will be discussed.

  10. Transition Radiation and its uses in particle accelerators

    NASA Astrophysics Data System (ADS)

    Silva, Tiago F.; Jahnke, Cristiane; Lima, Roberto R.; Malafronte, Alexandre A.; Vanin, Vito R.; Martins, Marcos N.

    2011-08-01

    Transition Radiation (TR) is a physical process in which a uniformly moving charge emits radiation. For emission to occur, it is necessary a variation of the electromagnetic properties of the media that surrounds the particle. The main characteristics of this kind of radiation are: linearity between the radiation intensity and the generating charge, polarization and formation time. The continuous spectrum covers a wide wavelength range, including visible light (Optical Transition Radiation—OTR). These characteristics make OTR an excellent tool for beam diagnostics in particle accelerators. In this work we discuss the role OTR plays in beam instrumentation and the progress of the undergoing project of an OTR based diagnostic tool for the IFUSP Microtron. This is an innovative design since it is planned to be used to diagnose a low energy and low current electron beam.

  11. Boundary conditions and generalized functions in a transition radiation problem

    NASA Astrophysics Data System (ADS)

    Villavicencio, M.; Jiménez, J. L.

    2017-03-01

    The aim of this work is to show how all the components of the electromagnetic field involved in the transition radiation problem can be obtained using distribution functions. The handling of the products and derivatives of distributions appearing in the differential equations governing transition radiation, allows to obtain the necessary boundary conditions, additional to those implied by Maxwell's equations, in order to exactly determine the longitudinal components of the electromagnetic field. It is shown that this method is not only useful but it is really convenient to achieve a full analysis of the problem.

  12. Transition radiation as a coherent soft X-ray source

    NASA Astrophysics Data System (ADS)

    Moran, M. A.; Dahling, B. A.; Piestrup, M. A.; Berman, B. L.; Kephart, J. O.

    A series of experiments performed at the LLNL using 54-MeV electrons to irradiate thin-foil targets has demonstrated the spatially coherent nature of soft X-ray transition radiation. Results of measurements and calculations demonstrate both the intrafoil and interfoil coherence of transition radiation in multiple-foil targets. It is noted that coherent behavior results in distinctive angular distributions that are accurately predicted by theoretical calculations. Possible applications of the present work are the investigation of the X-ray optical constants of thin foils and the development of a spatially coherent tunable soft X-ray laser.

  13. A large area transition radiation detector for the NOMAD experiment

    NASA Astrophysics Data System (ADS)

    Bassompierre, G.; Bermond, M.; Berthet, M.; Bertozzi, T.; Détraz, C.; Dubois, J.-M.; Dumps, L.; Engster, C.; Fazio, T.; Gaillard, G.; Gaillard, J.-M.; Gouanère, M.; Manola-Poggioli, E.; Mossuz, L.; Mendiburu, J.-P.; Nédélec, P.; Palazzini, E.; Pessard, H.; Petit, P.; Petitpas, P.; Placci, A.; Sillou, D.; Sottile, R.; Valuev, V.; Verkindt, D.; Vey, H.; Wachnik, M.

    1998-02-01

    A transition radiation detector to identify electrons at 90% efficiency with a rejection factor against pions of 10 3 on an area of 2.85 × 2.85 m 2 has been constructed for the NOMAD experiment. Each of its 9 modules includes a 315 plastic foil radiator and a detector plane of 176 vertical straw tubes filled with a xenon-methane gas mixture. Details of the design, construction and operation of the detector are given.

  14. Recent progress in the transition radiation detector techniques

    NASA Technical Reports Server (NTRS)

    Yuan, L. C. L.

    1973-01-01

    A list of some of the major experimental achievements involving charged particles in the relativistic region are presented. With the emphasis mainly directed to the X-ray region, certain modes of application of the transition radiation for the identification and separation of relativistic charged particles are discussed. Some recent developments in detection techniques and improvements in detector performances are presented. Experiments were also carried out to detect the dynamic radiation, but no evidence of such an effect was observed.

  15. Measuring radiative capture rates at DRAGON

    NASA Astrophysics Data System (ADS)

    Hager, U.; Davids, B.; Fallis, J.; Greife, U.; Hutcheon, D. A.; Rojas, A.; Ruiz, C.

    2013-04-01

    The DRAGON recoil separator facility is located at the ISAC facility at TRIUMF, Vancouver. It is designed to measure radiative alpha and proton capture reactions of astrophysical importance in inverse kinematics. The Supernanogan ion source at ISAC provides stable beams of high intensities. The DRAGON collaboration has taken advantage of this over the last years by measuring several reactions requiring high-intensity stable oxygen beams. In particular,the ^17O(p,γ) and ^16O(α,γ) reaction rates were recently measured. The former reaction is part of the hot CNO cycle, and strongly influences the abundance of ^18F in classical novae. Because of its relatively long lifetime, ^18F is a possible target for satellite-based gamma-ray spectroscopy. The ^16O(α,γ) reaction plays a role in steady-state helium burning in massive stars, where it follows the ^12C(α,γ) reaction. At astrophysically relevant energies, the reaction proceeds exclusively via direct capture, resulting in a low rate. In both cases, the unique capabilities of DRAGON enabled determination not only of the total reaction rates, but also of decay branching ratios. Results from both experiments will be presented.

  16. Radiative rates and electron impact excitation rate coefficients for Ne-like selenium, Se XXV

    NASA Astrophysics Data System (ADS)

    Wang, K.; Chen, C. Y.; Huang, M.; Wang, Y. S.; Zou, Y. M.

    2011-07-01

    In this article we report calculations of energy levels, radiative rates, electron impact collision strengths, and effective collision strengths for transitions among the 241 fine-structure levels arising from 2l8 and 2l7n'l' ( n'≤6 and l'≤n'-1) configurations of Ne-like Se XXV using the Flexible Atomic Code. Energy levels and radiative rates are calculated within the relativistic configuration-interaction method. Direct excitation collision strengths are calculated using the relativistic distorted-wave approximation and high-energy collision strengths are obtained in the relativistic plane-wave approximation. Resonance contributions through the relevant Na-like doubly-excited configurations 2l7n'l'n″l″ ( 3≤n'≤7, l'≤n'-1, n'≤n″≤50, and l″≤8) are explicitly taken into account via the independent-process and isolated-resonance approximation using distorted waves. Resonant stabilizing transitions and possibly important radiative decays from the resonances toward low-lying autoionizing levels are considered. In addition, the resonance contributions from Na-like 2l63l'3l″n‴l‴ ( n‴=3-6) configurations are included and found to be predominant for many transitions among the singly-excited states in Ne-like Se XXV. We present the radiative rates, oscillator strengths, and line strengths for all electric dipole, magnetic dipole, electric quadrupole, magnetic quadrupole, electric octopole, and magnetic octopole transitions among the 241 levels. The effective collision strengths are reported for all 28920 transitions among the 241 levels over a wide temperature range up to 10 keV. To assess the reliability and accuracy of the present collisional data, we have performed a 27-state close-coupling calculation, employing the Dirac R-matrix theory. The results from the close-coupling calculation and the independent-process calculation for the identical target states are found to be in good agreement.

  17. Relativistic Radiative and Auger Rates for Fe XXIV

    NASA Technical Reports Server (NTRS)

    Bautista, M. A.; Mendoza, C.; Kallman, T. R.; Palmeri, P.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    As part of a project to compute improved atomic data for the spectral modeling of iron K lines, we report extensive calculations and comparisons of radiative and Auger rates for transitions involving the K-vacancy states in Fe XXIV. By making use of several computational codes, a detailed study is carried out of orbital representation, configuration interaction, relativistic corrections, cancellation effects, and fine tuning. It is shown that a formal treatment of the Breit interaction is essential to render the important magnetic correlations that take part in the decay pathways of this ion. As a result, the accuracy of the present A-values is firmly ranked at better than 10% while that of the Auger rates at only 15%.

  18. Reaction rate constant for radiative association of CF{sup +}

    SciTech Connect

    Öström, Jonatan Gustafsson, Magnus; Bezrukov, Dmitry S.; Nyman, Gunnar

    2016-01-28

    Reaction rate constants and cross sections are computed for the radiative association of carbon cations (C{sup +}) and fluorine atoms (F) in their ground states. We consider reactions through the electronic transition 1{sup 1}Π → X{sup 1}Σ{sup +} and rovibrational transitions on the X{sup 1}Σ{sup +} and a{sup 3}Π potentials. Semiclassical and classical methods are used for the direct contribution and Breit–Wigner theory for the resonance contribution. Quantum mechanical perturbation theory is used for comparison. A modified formulation of the classical method applicable to permanent dipoles of unequally charged reactants is implemented. The total rate constant is fitted to the Arrhenius–Kooij formula in five temperature intervals with a relative difference of <3%. The fit parameters will be added to the online database KIDA. For a temperature of 10–250 K, the rate constant is about 10{sup −21} cm{sup 3} s{sup −1}, rising toward 10{sup −16} cm{sup 3} s{sup −1} for a temperature of 30 000 K.

  19. Reaction rate constant for radiative association of CF(.).

    PubMed

    Öström, Jonatan; Bezrukov, Dmitry S; Nyman, Gunnar; Gustafsson, Magnus

    2016-01-28

    Reaction rate constants and cross sections are computed for the radiative association of carbon cations (C(+)) and fluorine atoms (F) in their ground states. We consider reactions through the electronic transition 1(1)Π → X(1)Σ(+) and rovibrational transitions on the X(1)Σ(+) and a(3)Π potentials. Semiclassical and classical methods are used for the direct contribution and Breit-Wigner theory for the resonance contribution. Quantum mechanical perturbation theory is used for comparison. A modified formulation of the classical method applicable to permanent dipoles of unequally charged reactants is implemented. The total rate constant is fitted to the Arrhenius-Kooij formula in five temperature intervals with a relative difference of <3%. The fit parameters will be added to the online database KIDA. For a temperature of 10-250 K, the rate constant is about 10(-21) cm(3) s(-1), rising toward 10(-16) cm(3) s(-1) for a temperature of 30,000 K.

  20. Coulomb gauge approach for charmonium meson and hybrid radiative transitions

    SciTech Connect

    Gou, Peng; Yepez-Martínez, Tochtli; Szczepaniak, Adam P.

    2015-01-22

    We consider the lowest order interaction of the Foldy-Wouthuysen QED and QCD Hamiltonian in the Coulomb gauge approach, to describe radiative transitions between conventional and hybrids charmonium mesons. The results are compared to potential quark models and lattices calculations.

  1. The efficient identification of relativistic particles by transition radiation

    NASA Technical Reports Server (NTRS)

    Cherry, M. L.; Mueller, D.; Prince, T. A.

    1974-01-01

    A system of transition radiation detectors has been constructed and exposed to beams of electrons and pions in the energy range of 3 to 15 GeV at SLAC. Transition radiation was generated in a variety of stacks of mylar foils (radiators), and its intensity was detected with 7 multiwire proportional chambers. The raw data demonstrate a good separation between electron and pion induced signals. A more detailed analysis shows that a very efficient identification of individual particles is possible. Typically, a detection efficiency for electrons above 90%, combined with a pion-electron discrimination ratio of .001, has been achieved. Some conclusions with respect to the design of a practical detector for relativistic particles are drawn.

  2. Atomic transition rates for neutral holmium (Ho I)

    NASA Astrophysics Data System (ADS)

    Nave, Gillian

    2003-10-01

    Transition rates for 321 lines between 345 and 1080 nm from 73 levels of Ho I are presented. They have been measured by combining branching fractions obtained by Fourier transform spectrometry with lifetimes of Den Hartog et al. [J. Opt. Soc. Am. B 6, 2278 (1999)]. The uncertainty of the transition rates is 5%-10%.

  3. Cerenkov and transition radiation in space-time periodic media.

    NASA Technical Reports Server (NTRS)

    Elachi, C.

    1972-01-01

    The solution to the problem of determining the radiation emitted by a uniformly moving charged particle in a sinusoidally space-time periodic medium is obtained. The space-time periodicity can be considered as due to a strong pump wave and is expressed as a traveling-wave-type change in the dielectric constant or the plasma density. The solution covers also the limiting case of sinusoidally stratified media. The expression and spectrum of the radiated electromagnetic field are determined for different media: dielectric, isotropic and uniaxial plasma. Depending on the nature of the medium and the velocity of the particle, the radiated field is of the Cerenkov and/or transition type. The Brillouin diagram is used extensively in understanding and determining the nature, extent, and spectrum of the different modes of radiation, and a focusing effect is also studied.

  4. Three-Dimensional Analysis of Optical Transition Radiation

    DTIC Science & Technology

    1988-12-01

    may be observed from the front face of the foil and is called backward transition radiation siliCe it is reflected back fLou- the foil. Transition...reflection coefficients. The Lorentz factor , aPI the velocity / are defined E -1+ KE , (2.3) and ~= - (2.4) The parallel and perpendicular reflection...Re[(-y-N2Z/ax)W(Z)+ax (2/ )l/2] , (2.8) where Z is defined as (I +i0)/a, ax as the rms beam angle of divergence projected into the observation plane

  5. Radiative heating rates during AAOE and AASE. [Airborne Antarctic Ozone Experiment and Airborne Arctic Stratospheric Experiment

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.

    1990-01-01

    Radiative transit computations of heating rates utilizing data from the 1987 Airborne Antarctic Ozone Experiment (AAOE) (Tuck et al., 1989) and the 1989 Airborne Arctic Stratospheric Experiment (AASE) (Turco et al., 1990) are described. Observed temperature and ozone profiles and a radiative transfer model are used to compute the heating rates for the Southern Hemisphere during AAOE and the Northern Hemisphere during AASE. The AASE average cooling rates computed inside the vortex are in good agreement with the diabatic cooling rates estimated from the ER-2 profile data for N2O for the AASE period (Schoeberl et al., 1989).

  6. Classical theory of resonant transition radiation in multilayer structures.

    PubMed

    Pardo, B; André, J M

    2001-01-01

    A rigorous classical electromagnetic theory of the transition radiation in finite and infinite multilayer structures is presented. It makes the standard results of thin-film optics, such as the matrix formalism, accountable; it allows thus an exact treatment of the propagation of the waves induced by the electron. This method is applied to the particular case of the periodic structures to treat the resonant transition radiation (RTR). It is noted that the present theory gives, in the hard x-ray domain, results previously published. The reason for this approach is to make the numerical calculations rigorous and easy. The numerical results of our theory are compared to experimental RTR data obtained recently by Yamada et al. [Phys. Rev. A 59, 3673 (1999)] with a nickel-carbon multilayer structure.

  7. Can transition radiation explain the ANITA event 3985267?

    NASA Astrophysics Data System (ADS)

    Motloch, Pavel; Alvarez-Muñiz, Jaime; Privitera, Paolo; Zas, Enrique

    2017-02-01

    We investigate whether transition radiation from a particle shower crossing the interface between Earth and air and induced by an Earth-skimming neutrino can explain the upward event announced recently by the ANITA Collaboration. While the properties of the observed signal can in principle be explained with transition radiation, a conservative upper limit on the experiment's aperture for this kind of signal shows that the flux necessary for a successful explanation is in tension with the current best limits from the Pierre Auger Observatory, the IceCube neutrino detector, and the ANITA balloon. We also show that in this scenario, the direction of the incoming neutrino is determined precisely to within a few degrees, combining the polarization properties of the observed events with the Earth opacity to ultrahigh energy neutrinos.

  8. Diffraction effects in the coherent transition radiation bunch length diagnostics

    SciTech Connect

    Kazakevich, G.; Lebedev, V.; Nagaitsev, S.; /Fermilab

    2007-08-01

    Diffraction effects in the Coherent Transition Radiation (CTR) bunch length diagnostics are considered for the A0 Photoinjector and the New Muon Laboratory (NML) injection module. The effects can cause a noticeable distortion of the measured CTR spectra depending on the experimental setup and the bunch parameters and resulting in errors of the bunch length measurements. Presented calculations show possible systematic errors in the bunch length in measurements based on the CTR spectra at A0 Photo injector and the NML injection module.

  9. Estimation of transition probabilities of credit ratings for several companies

    NASA Astrophysics Data System (ADS)

    Peng, Gan Chew; Hin, Pooi Ah

    2016-10-01

    This paper attempts to estimate the transition probabilities of credit ratings for a number of companies whose ratings have a dependence structure. Binary codes are used to represent the index of a company together with its ratings in the present and next quarters. We initially fit the data on the vector of binary codes with a multivariate power-normal distribution. We next compute the multivariate conditional distribution for the binary codes of rating in the next quarter when the index of the company and binary codes of the company in the present quarter are given. From the conditional distribution, we compute the transition probabilities of the company's credit ratings in two consecutive quarters. The resulting transition probabilities tally fairly well with the maximum likelihood estimates for the time-independent transition probabilities.

  10. Natural transition from rate to force control of a manipulator

    NASA Technical Reports Server (NTRS)

    Harrison, F. W.; Soloway, Don; Williams, Robert L.; Hogge, Edward F.

    1992-01-01

    A method for teleoperator control which offers advantages over previous techniques is demonstrated. In the new method, a fundamental variable exchanged between the master and slave is the rate of change in position and force. An inherent capability of the control scheme is demonstrated for transition between control methods based on environmental constraints in a manner natural to the operator. Specifically, rate control of a manipulator makes the transition to force-force control when a force-reflecting hand controller is used with a local force accommodation algorithm running on the remote manipulator. The transition from rate to force occurs when contact is made with the environment.

  11. Modifications to population rate equations resulting from correlations between collisional and radiative processes

    NASA Technical Reports Server (NTRS)

    Ballagh, R. J.; Cooper, J.

    1984-01-01

    There are many systems of physical interest for which a set of rate equations for level populations can provide insight. If the system has two (or more) different mechanisms for effecting transition between levels, total rates of transfer are usually taken as the sum of rates that the individual mechanisms would cause acting alone. Using the example of a hydrogen atom subjected to (ionic and electronic) collisions and external radiation, it is shown that when these individual mechanisms overlap, the total transfer rates must be modified to account for correlations between collisional and radiative processes. For a broad-band radiation field the modified rates have a simple physical interpretation. In the case of a narrow-band field the overlapping events may cause new coherences to appear and interpretation of the modified 'rates' is more complicated.

  12. Radiation rates for low Z impurities in edge plasmas

    SciTech Connect

    Clark, R.; Abdallah, J.; Post, D.

    1994-08-01

    The potential role of impurity radiation in the reduction of heat loads on divertor plates places a new degree of importance on the accuracy of low Z impurity radiation emission rates for electron temperatures below 300 eV. We have calculated the radiated power loss using a collisional-radiative model for Be, B, C, Ne and Ar using a multiple configuration interaction model which includes density dependent effects, as well as a very detailed treatment of the energy levels and meta-stables. These rates indicate that significant enhancements above steady state collisional-radiative rates due to such effects as rapid recycling and charge exchange recombination will be necessary for impurity radiation to reduce the peak heat loads on divertor plates for high heat flux experiments such as ITER.

  13. Transition to the radiative phase in supernova remnant evolution

    NASA Astrophysics Data System (ADS)

    Wright, Eric Boyd

    1999-11-01

    The evolution of a supernova remnant (SNR) through the transition from an adiabatic Sedov-Taylor blastwave to a radiative pressure-driven snowplow phase is studied through a series of one-, two- and three-dimensional hydrodynamic (HD) and magnetohydrodynamic (MHD) simulations. This transition is marked by a catastrophic collapse of the postshock gas, forming a thin, dense shell behind the forward shock. Previous studies have shown that the thin, dense shell of gas present during this transition is susceptible to both radiative and dynamical instabilities. One-dimensional HD studies indicate the presence of a radial oscillation between the forward shock and the thin shell, due to the rapid cooling of the gas in the immediate postshock region. Two-dynamical HD simulations of this transition indicate the presence of violent dynamical instabilities that alter the initially spherical morphology of the blastwave, specifically, the Pressure-driven Thin Shell Overstability (PDTSO) and the Non-linear Thin Shell Instability (NTSI). Hydrodynamical simulations, by their very nature, ignore the effects of magnetic forces on moving fluids. In general, interstellar magnetic fields will be weak enough that their effects may be safely ignored. However, the transition to the radiative phase in SNR evolution is often triggered when the blastwave interacts with dense clouds of gas in the interstellar medium (ISM). The resulting compression of the gas during the transition also compresses the magnetic fields in the cloud, possibly enhancing the field sufficiently to play a role in the further evolution of the SNR. To better understand the role of the NTSI during the transition, and to study the effects of magnetic fields on the instability itself, we performed idealized two- and three-dimensional MHD simulations. The results of the two-dimensional simulations were found to depend strongly on the orientation of the ambient magnetic field when the postshock field is dynamically

  14. Transition probabilities and radiative lifetimes of Mg III

    NASA Astrophysics Data System (ADS)

    Alonso-Medina, A.; Colón, C.; Moreno-Díaz, C.

    2015-03-01

    There have been calculated transition probabilities for 365 lines arising from 2p5 n s(n = 3 , 4 , 5) , 2p5 n p(n = 3 , 4) , 2p5 n d(n = 3 , 4) , 2p5 n f(n = 4 , 5) and 2p5 5g configurations of Mg III and radiative lifetimes corresponding to 89 levels. These values were obtained in intermediate coupling (IC) by using ab initio relativistic Hartree-Fock (HFR) calculations. Later, we use the standard method of least square fitting of experimental energy levels for the IC calculations by means of Cowan's computer codes. The vast majority of the calculated transition probabilities correspond to lines lying in the ultraviolet range (UV) which are of high interest in astrophysics. Our results are compared to those previously reported in the literature. Furthermore, the values of transition probabilities of configuration levels 2p5 4d, 2p5 n f(n = 4 , 5) and 2p5 5g are presented for the first time. In light of these findings, it is possible to extend the range of wavelengths which allows us to estimate the temperature in plasma diagnostic. In addition, our results for radiative lifetimes have been compared to the available experimental values.

  15. Radiation dose rates from UF{sub 6} cylinders

    SciTech Connect

    Friend, P.J.

    1991-12-31

    This paper describes the results of many studies, both theoretical and experimental, which have been carried out by Urenco over the last 15 years into radiation dose rates from uranium hexafluoride (UF{sub 6}) cylinders. The contents of the cylinder, its history, and the geometry all affect the radiation dose rate. These factors are all examined in detail. Actual and predicted dose rates are compared with levels permitted by IAEA transport regulations.

  16. Energy levels and radiative rates for Cr-like Cu VI and Zn VII

    NASA Astrophysics Data System (ADS)

    Aggarwal, K. M.; Bogdanovich, P.; Keenan, F. P.; Kisielius, R.

    2016-09-01

    Energy levels and radiative rates (A-values) for transitions in Cr-like Cu VI and Zn VII are reported. These data are determined in the quasi-relativistic approach (QR), by employing a very large configuration interaction (CI) expansion which is highly important for these ions. No radiative rates are available in the literature to compare with our results, but our calculated energies are in close agreement with those compiled by NIST and other available theoretical data, for a majority of the levels. The A-values (and resultant lifetimes) are listed for all significantly contributing E1, E2 and M1 radiative transitions among the energetically lowest 322 levels of each ion.

  17. Control of atomic transition rates via laser-light shaping

    NASA Astrophysics Data System (ADS)

    Jáuregui, R.

    2015-04-01

    A modular systematic analysis of the feasibility of modifying atomic transition rates by tailoring the electromagnetic field of an external coherent light source is presented. The formalism considers both the center of mass and internal degrees of freedom of the atom, and all properties of the field: frequency, angular spectrum, and polarization. General features of recoil effects for internal forbidden transitions are discussed. A comparative analysis of different structured light sources is explicitly worked out. It includes spherical waves, Gaussian beams, Laguerre-Gaussian beams, and propagation invariant beams with closed analytical expressions. It is shown that increments in the order of magnitude of the transition rates for Gaussian and Laguerre-Gaussian beams, with respect to those obtained in the paraxial limit, require waists of the order of the wavelength, while propagation invariant modes may considerably enhance transition rates under more favorable conditions. For transitions that can be naturally described as modifications of the atomic angular momentum, this enhancement is maximal (within propagation invariant beams) for Bessel modes, Mathieu modes can be used to entangle the internal and center-of-mass involved states, and Weber beams suppress this kind of transition unless they have a significant component of odd modes. However, if a recoil effect of the transition with an adequate symmetry is allowed, the global transition rate (center of mass and internal motion) can also be enhanced using Weber modes. The global analysis presented reinforces the idea that a better control of the transitions between internal atomic states requires both a proper control of the available states of the atomic center of mass, and shaping of the background electromagnetic field.

  18. A Study of Radiative Bottomonium Transitions using Converted Photons

    SciTech Connect

    Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Milanes, D.A.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Brown, D.N.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; Koch, H.; Schroeder, T.; Asgeirsson, D.J.; Hearty, C.; /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /Indian Inst. Tech., Guwahati /Harvard U. /Harvey Mudd Coll. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa State U. /Iowa State U. /Johns Hopkins U. /Paris U., VI-VII /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /INFN, Naples /Naples U. /NIKHEF, Amsterdam /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /Rostock U. /Rutherford /DAPNIA, Saclay /SLAC /South Carolina U. /Southern Methodist U. /Stanford U., Phys. Dept. /SUNY, Albany /Tel Aviv U. /Tennessee U. /Texas Nuclear Corp., Austin /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U. /Victoria U. /Warwick U. /Wisconsin U., Madison

    2011-08-15

    The authors use (111 {+-} 1) million {Upsilon}(3S) and (89 {+-} 1) million {Upsilon}(2S) events recorded by the BABAR detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions betwen bottomonium states using photons that have been converted to e{sup +}e{sup -} pairs by the detector material. They observe {Upsilon}(3S) {yields} {gamma}{chi}{sub b0,2}(1P) decay, make precise measurements of the branching fractions for {chi}{sub b1,2}(1P, 2P) {yields} {gamma}{Upsilon}(1S) and {chi}{sub b1,2}(2P) {yields} {gamma}{Upsilon}(2S) decays, and search for radiative decay to the {eta}{sub b}(1S) and {eta}{sub b}(2S) states.

  19. Reversed Cherenkov transition radiation of charge entering anisotropic medium

    NASA Astrophysics Data System (ADS)

    Galyamin, S. N.; Tyukhtin, A. V.

    2011-04-01

    The electromagnetic field of a charge crossing the interface between vacuum and an electrically anisotropic dispersive medium in which reversed Cherenkov transition radiation (RCTR) is generated has been theoretically studied. An algorithm for calculating the Fourier harmonics of the field based on exact formulas is developed and their asymptotics in the far field zone are determined. A special attention is devoted to the RCTR phenomenon, which was previously only studied for the so-called left-handed medium (LHM). Conditions for RCTR excitation are found and the effect of losses in the medium on the propagation of radiation is analyzed. The RCTR under the indicated conditions is compared to the analogous effect in LHM.

  20. Radiation torque on nonspherical particles in the transition matrix formalism

    NASA Astrophysics Data System (ADS)

    Borghese, Ferdinando; Denti, Paolo; Saija, Rosalba; Iatì, Maria A.

    2006-10-01

    The torque exerted by radiation on small particles is recognized to have a considerable relevance, e.g., on the dynamics of cosmic dust grains and for the manipulation of micro and nanoparticles under controlled conditions. In the present paper we derive, in the transition matrix formalism, the radiation torque applied by a plane polarized wave on nonspherical particles. In case of circularly polarized waves impinging on spherical particles our equations reproduce the findings of Marston and Crichton [Phys. Rev. A 30, 2508 2516 (1984)]. Our equations were applied to calculate the torque on a few model particles shaped as aggregates of identical spheres, both axially symmetric and lacking any symmetry, and the conditions for the stability of the induced rotational motion are discussed.

  1. The transition radiation detector of the PAMELA space mission

    NASA Astrophysics Data System (ADS)

    Ambriola, M.; Bellotti, R.; Cafagna, F.; Circella, M.; de Marzo, C.; Giglietto, N.; Marangelli, B.; Mirizzi, N.; Romita, M.; Spinelli, P.

    2004-04-01

    PAMELA space mission objective is to flight a satellite-borne magnetic spectrometer built to fulfill the primary scientific goals of detecting antiparticles (antiprotons and positrons) and to measure spectra of particles in cosmic rays. The PAMELA telescope is composed of: a silicon tracker housed in a permanent magnet, a time-of-flight and an anticoincidence system both made of plastic scintillators, a silicon imaging calorimeter, a neutron detector and a Transition Radiation Detector (TRD). The TRD is composed of nine sensitive layers of straw tubes working in proportional mode for a total of 1024 channels. Each layer is interleaved with a radiator plane made of carbon fibers. The TRD characteristics will be described along with its performances studied at both CERN-PS and CERN-SPS facilities, using electrons, pions, muons and protons of different momenta.

  2. Simulation of transition radiation based beam imaging from tilted targets

    NASA Astrophysics Data System (ADS)

    Sukhikh, L. G.; Kube, G.; Potylitsyn, A. P.

    2017-03-01

    Transverse beam profile diagnostics in linear electron accelerators is usually based on direct imaging of a beam spot via visible transition radiation. In this case the fundamental resolution limit is determined by radiation diffraction in the optical system. A method to measure beam sizes beyond the diffraction limit is to perform imaging dominated by a single-particle function (SPF), i.e. when the recorded image is dominated not by the transverse beam profile but by the image function of a point source (single electron). Knowledge of the SPF for an experimental setup allows one to extract the transverse beam size from an SPF dominated image. This paper presents an approach that allows one to calculate two-dimensional SPF dominated beam images, taking into account the target inclination angle and the depth-of-field effect. In conclusion, a simple fit function for beam size determination in the case under consideration is proposed and its applicability is tested under various conditions.

  3. Radiation damage of transition metal carbides. Final technical report

    SciTech Connect

    Dixon, G.

    1991-12-31

    In this grant period we have investigated electrical properties of transition metal carbides and radiation-induced defects produced by low-temperature electron irradiation in them. Special attention has been given to the composition VC{sub 0.88} in which the vacancies on the carbon sublattice of this fcc crystal order to produce a V{sub 8}C{sub 7} superlattice. The existence of this superlattice structure was found to make the crystal somewhat resistant to radiation damage at low doses and/or at ambient temperature. At larger doses significant changes in the resistivity are produced. Annealing effects were observed which we believe to be connected with the reconstitution of the superlattice structure.

  4. Phase Transition in a Healthy Human Heart Rate

    NASA Astrophysics Data System (ADS)

    Kiyono, Ken; Struzik, Zbigniew R.; Aoyagi, Naoko; Togo, Fumiharu; Yamamoto, Yoshiharu

    2005-07-01

    A healthy human heart rate displays complex fluctuations which share characteristics of physical systems in a critical state. We demonstrate that the human heart rate in healthy individuals undergoes a dramatic breakdown of criticality characteristics, reminiscent of continuous second order phase transitions. By studying the germane determinants, we show that the hallmark of criticality—highly correlated fluctuations—is observed only during usual daily activity, and a breakdown of these characteristics occurs in prolonged, strenuous exercise and sleep. This finding is the first reported discovery of the dynamical phase transition phenomenon in a biological control system and will be a key to understanding the heart rate control system in health and disease.

  5. Pulse wave transit time for monitoring respiration rate.

    PubMed

    Johansson, A; Ahlstrom, C; Lanne, T; Ask, P

    2006-06-01

    In this study, we investigate the beat-to-beat respiratory fluctuations in pulse wave transit time (PTT) and its subcomponents, the cardiac pre-ejection period (PEP) and the vessel transit time (VTT) in ten healthy subjects. The three transit times were found to fluctuate in pace with respiration. When applying a simple breath detecting algorithm, 88% of the breaths seen in a respiration air-flow reference could be detected correctly in PTT. Corresponding numbers for PEP and VTT were 76 and 81%, respectively. The performance during hypo- and hypertension was investigated by invoking blood pressure changes. In these situations, the error rates in breath detection were significantly higher. PTT can be derived from signals already present in most standard monitoring set-ups. The transit time technology thus has prospects to become an interesting alternative for respiration rate monitoring.

  6. Gold nanoparticles quench fluorescence by phase induced radiative rate suppression.

    PubMed

    Dulkeith, E; Ringler, M; Klar, T A; Feldmann, J; Muñoz Javier, A; Parak, W J

    2005-04-01

    The fluorescence quantum yield of Cy5 molecules attached to gold nanoparticles via ssDNA spacers is measured for Cy5-nanoparticle distances between 2 and 16 nm. Different numbers of ssDNA per nanoparticle allow to fine-tune the distance. The change of the radiative and nonradiative molecular decay rates with distance is determined using time-resolved photoluminescence spectroscopy. Remarkably, the distance dependent quantum efficiency is almost exclusively governed by the radiative rate.

  7. Exotic and excited-state meson spectroscopy and radiative transitions from lattice QCD

    SciTech Connect

    Christopher Thomas

    2010-09-01

    We discuss recent progress in extracting the excited meson spectrum and radiative transition form factors using lattice QCD. We mention results in the charmonium sector, including the first lattice QCD calculation of radiative transition rates involving excited charmonium states, highlighting results for high spin and exotic states. We present recent results on a highly excited isovector meson spectrum from dynamical anisotropic lattices. Using carefully constructed operators we show how the continuum spin of extracted states can be reliably identified and confidently extract excited states, states with exotic quantum numbers and states of high spin. This spectrum includes the first spin-four state extracted from lattice QCD. We conclude with some comments on future prospects.

  8. Transition radiation in metal-metal multilayer nanostructures as a medical source of hard x-ray radiation

    SciTech Connect

    Pokrovsky, A. L.; Kaplan, A. E.; Shkolnikov, P. L.

    2006-08-15

    We show that a periodic metal-metal multilayer nanostructure can serve as an efficient source of hard x-ray transition radiation. Our research effort is aimed at developing an x-ray source for medical applications, which is based on using low-energy relativistic electrons. The approach toward choosing radiator-spacer couples for the generation of hard x-ray resonant transition radiation by few-MeV electrons traversing solid multilayer structures for the energies of interest to medicine (30-50 keV) changes dramatically compared with that for soft x-ray radiation. We show that one of the main factors in achieving the required resonant line is the absence of the contrast of the refractive indices between the spacer and the radiator at the far wings of the radiation line; for that purpose, the optimal spacer, as a rule, should have a higher atomic number than the radiator. Having experimental goals in mind, we have considered also the unwanted effects due to bremsstrahlung radiation, absorption and scattering of radiated photons, detector-related issues, and inhibited coherence of transition radiation due to random deviation of spacing between the layers. Choosing as a model example a Mo-Ag radiator-spacer pair of materials, we demonstrate that the x-ray transition radiation line can be well resolved with the use of spatial and frequency filtering.

  9. Exciton radiative lifetime in transition metal dichalcogenide monolayers

    NASA Astrophysics Data System (ADS)

    Robert, C.; Lagarde, D.; Cadiz, F.; Wang, G.; Lassagne, B.; Amand, T.; Balocchi, A.; Renucci, P.; Tongay, S.; Urbaszek, B.; Marie, X.

    2016-05-01

    We have investigated the exciton dynamics in transition metal dichalcogenide monolayers using time-resolved photoluminescence experiments performed with optimized time resolution. For MoS e2 monolayer, we measure τrad0=1.8 ±0.2 ps at T =7 K that we interpret as the intrinsic radiative recombination time. Similar values are found for WS e2 monolayers. Our detailed analysis suggests the following scenario: at low temperature (T ≲50 K ), the exciton oscillator strength is so large that the entire light can be emitted before the time required for the establishment of a thermalized exciton distribution. For higher lattice temperatures, the photoluminescence dynamics is characterized by two regimes with very different characteristic times. First the photoluminescence intensity drops drastically with a decay time in the range of the picosecond driven by the escape of excitons from the radiative window due to exciton-phonon interactions. Following this first nonthermal regime, a thermalized exciton population is established gradually yielding longer photoluminescence decay times in the nanosecond range. Both the exciton effective radiative recombination and nonradiative recombination channels including exciton-exciton annihilation control the latter. Finally the temperature dependence of the measured exciton and trion dynamics indicates that the two populations are not in thermodynamical equilibrium.

  10. Elevated Rate of Genome Rearrangements in Radiation-Resistant Bacteria

    PubMed Central

    Repar, Jelena; Supek, Fran; Klanjscek, Tin; Warnecke, Tobias; Zahradka, Ksenija; Zahradka, Davor

    2017-01-01

    A number of bacterial, archaeal, and eukaryotic species are known for their resistance to ionizing radiation. One of the challenges these species face is a potent environmental source of DNA double-strand breaks, potential drivers of genome structure evolution. Efficient and accurate DNA double-strand break repair systems have been demonstrated in several unrelated radiation-resistant species and are putative adaptations to the DNA damaging environment. Such adaptations are expected to compensate for the genome-destabilizing effect of environmental DNA damage and may be expected to result in a more conserved gene order in radiation-resistant species. However, here we show that rates of genome rearrangements, measured as loss of gene order conservation with time, are higher in radiation-resistant species in multiple, phylogenetically independent groups of bacteria. Comparison of indicators of selection for genome organization between radiation-resistant and phylogenetically matched, nonresistant species argues against tolerance to disruption of genome structure as a strategy for radiation resistance. Interestingly, an important mechanism affecting genome rearrangements in prokaryotes, the symmetrical inversions around the origin of DNA replication, shapes genome structure of both radiation-resistant and nonresistant species. In conclusion, the opposing effects of environmental DNA damage and DNA repair result in elevated rates of genome rearrangements in radiation-resistant bacteria. PMID:28188144

  11. J/psi and psi(2S) Radiative Transitions to eta_{c}.

    PubMed

    Mitchell, R E; Shepherd, M R; Besson, D; Pedlar, T K; Cronin-Hennessy, D; Gao, K Y; Hietala, J; Kubota, Y; Klein, T; Lang, B W; Poling, R; Scott, A W; Zweber, P; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A; Libby, J; Powell, A; Wilkinson, G; Ecklund, K M; Love, W; Savinov, V; Lopez, A; Mendez, H; Ramirez, J; Ge, J Y; Miller, D H; Shipsey, I P J; Xin, B; Adams, G S; Anderson, M; Cummings, J P; Danko, I; Hu, D; Moziak, B; Napolitano, J; He, Q; Insler, J; Muramatsu, H; Park, C S; Thorndike, E H; Yang, F; Artuso, M; Blusk, S; Khalil, S; Li, J; Mountain, R; Nisar, S; Randrianarivony, K; Sultana, N; Skwarnicki, T; Stone, S; Wang, J C; Zhang, L M; Bonvicini, G; Cinabro, D; Dubrovin, M; Lincoln, A; Naik, P; Rademacker, J; Asner, D M; Edwards, K W; Reed, J; Briere, R A; Ferguson, T; Tatishvili, G; Vogel, H; Watkins, M E; Rosner, J L; Alexander, J P; Cassel, D G; Duboscq, J E; Ehrlich, R; Fields, L; Galik, R S; Gibbons, L; Gray, R; Gray, S W; Hartill, D L; Heltsley, B K; Hertz, D; Hunt, J M; Kandaswamy, J; Kreinick, D L; Kuznetsov, V E; Ledoux, J; Mahlke-Krüger, H; Mohapatra, D; Onyisi, P U E; Patterson, J R; Peterson, D; Riley, D; Ryd, A; Sadoff, A J; Shi, X; Stroiney, S; Sun, W M; Wilksen, T; Athar, S B; Patel, R; Yelton, J; Rubin, P; Eisenstein, B I; Karliner, I; Mehrabyan, S; Lowrey, N; Selen, M; White, E J; Wiss, J

    2009-01-09

    Using 2.45x10;{7} psi(2S) decays collected with the CLEO-c detector at the Cornell Electron Storage Ring we present the most precise measurements of magnetic dipole transitions in the charmonium system. We measure B(psi(2S)-->gammaeta_{c})=(4.32+/-0.16+/-0.60)x10;{-3}, B(J/psi-->gammaeta_{c})/B(psi(2S)-->gammaeta_{c})=4.59+/-0.23+/-0.64, and B(J/psi-->gammaeta_{c})=(1.98+/-0.09+/-0.30)%. We observe a distortion in the eta_{c} line shape due to the photon-energy dependence of the magnetic dipole transition rate. We find that measurements of the eta_{c} mass are sensitive to the line shape, suggesting an explanation for the discrepancy between measurements of the eta_{c} mass in radiative transitions and other production mechanisms.

  12. Coherent x-ray transition and diffraction radiation of microbunched beams

    NASA Astrophysics Data System (ADS)

    Ispirian, K. A.; Ispiryan, M.

    2013-02-01

    Theoretical and numerical results on angular and spectral distributions and total number of photons of several types of coherent radiation produced by microbunched beams passing through radiators are presented: coherent x-ray bremsstrahlung, x-ray transition, resonance transition, and diffraction radiations. The possibility of observation and application of these new types of radiation for the study of parameters of electron beam microbunching, which is important for the effectiveness of x-ray free electron lasers, is discussed.

  13. Phenomenology of heavy quarkonium radiative E1 transitions

    SciTech Connect

    Martinez, Hector E.

    2016-01-22

    We present preliminary results of the evaluation of the next-to-leading-order (NLO) relativistic corrections to the heavy quarkonium electric dipole transition (E1) rate. In our evaluation we use the quark-antiquark potential up to 1/m{sup 2} corrections that includes the effective string theory expression for the long range, a review on the method to construct this potential is given. Our results compare favorable with the experiments and may provide predictions for the rates for which no experimental data is yet available.

  14. Effects Of Dose Rates On Radiation Damage In CMOS Parts

    NASA Technical Reports Server (NTRS)

    Goben, Charles A.; Coss, James R.; Price, William E.

    1990-01-01

    Report describes measurements of effects of ionizing-radiation dose rate on consequent damage to complementary metal oxide/semiconductor (CMOS) electronic devices. Depending on irradiation time and degree of annealing, survivability of devices in outer space, or after explosion of nuclear weapons, enhanced. Annealing involving recovery beyond pre-irradiation conditions (rebound) detrimental. Damage more severe at lower dose rates.

  15. Accurate transition rates for intercombination lines of singly ionized nitrogen

    NASA Astrophysics Data System (ADS)

    Tayal, S. S.

    2011-01-01

    The transition energies and rates for the 2s22p2 3P1,2-2s2p3 5S2o and 2s22p3s-2s22p3p intercombination transitions have been calculated using term-dependent nonorthogonal orbitals in the multiconfiguration Hartree-Fock approach. Several sets of spectroscopic and correlation nonorthogonal functions have been chosen to describe adequately term dependence of wave functions and various correlation corrections. Special attention has been focused on the accurate representation of strong interactions between the 2s2p3 1,3P1o and 2s22p3s 1,3P1olevels. The relativistic corrections are included through the one-body mass correction, Darwin, and spin-orbit operators and two-body spin-other-orbit and spin-spin operators in the Breit-Pauli Hamiltonian. The importance of core-valence correlation effects has been examined. The accuracy of present transition rates is evaluated by the agreement between the length and velocity formulations combined with the agreement between the calculated and measured transition energies. The present results for transition probabilities, branching fraction, and lifetimes have been compared with previous calculations and experiments.

  16. Accurate transition rates for intercombination lines of singly ionized nitrogen

    SciTech Connect

    Tayal, S. S.

    2011-01-15

    The transition energies and rates for the 2s{sup 2}2p{sup 2} {sup 3}P{sub 1,2}-2s2p{sup 3} {sup 5}S{sub 2}{sup o} and 2s{sup 2}2p3s-2s{sup 2}2p3p intercombination transitions have been calculated using term-dependent nonorthogonal orbitals in the multiconfiguration Hartree-Fock approach. Several sets of spectroscopic and correlation nonorthogonal functions have been chosen to describe adequately term dependence of wave functions and various correlation corrections. Special attention has been focused on the accurate representation of strong interactions between the 2s2p{sup 3} {sup 1,3}P{sub 1}{sup o} and 2s{sup 2}2p3s {sup 1,3}P{sub 1}{sup o}levels. The relativistic corrections are included through the one-body mass correction, Darwin, and spin-orbit operators and two-body spin-other-orbit and spin-spin operators in the Breit-Pauli Hamiltonian. The importance of core-valence correlation effects has been examined. The accuracy of present transition rates is evaluated by the agreement between the length and velocity formulations combined with the agreement between the calculated and measured transition energies. The present results for transition probabilities, branching fraction, and lifetimes have been compared with previous calculations and experiments.

  17. Optical transition radiation interferometry for the A0 photoinjector

    SciTech Connect

    Kazakevich, G.; Edwards, H.; Fliller, R.; Nagaitsev, S.; Ruan, J.; Thurman-Keup, R.; /Fermilab

    2008-06-01

    Optical Transition Radiation Interferometry (OTRI) is a promising diagnostic technique and has been successfully developed and used for investigation of relativistic beams. For mid-energy accelerators the technique is traditionally based on thin polymer films (the first one is being transparent for visible light), which causes beam multiple scattering of about 1 mrad. A disadvantage of those films is unacceptable vacuum properties for photoinjectors and accelerators using superconducting cavities. We have studied the application of thin mica sheets for the OTRI diagnostics at the A0 Photoinjector in comparison with 2.5 {micro}m thick Mylar films. This diagnostic is also applicable for the ILCTA-NML accelerator test facility that is planned at Fermilab. This report discusses the experimental setups of the OTR interferometer for the A0 Photoinjector and presents comparisons of simulations and measurements obtained using Mylar and mica-based interferometers.

  18. Radiative Transitions of the Y(4260) at BES

    NASA Astrophysics Data System (ADS)

    Lara, Manuel

    2014-03-01

    The recent discoveries of the so called ``XYZ'' states are beginning to open new possibilities for how quarks can interact and bind. Detailed studies of their decays are underway in many facilities like the BES detector which has collected a total of 2.092 fb-1 of data at 4260, 4360, 4230 MeV to study the Y(4260). While the nature of the Y(4260) is still unknown two particularly important decay channels to study would be radiative decays to ηc and χc 0, because their branching fraction ratio could be compared to existing E1/M1 branching fractions of conventional charmonium and to lattice qcd predictions. The prospects for measuring such transitions using data collected with the BES detector will be presented.

  19. Radiative Transitions of the Y(4260) at BES III

    NASA Astrophysics Data System (ADS)

    Lara, Manuel

    2015-04-01

    The recent discoveries of the so called ``XYZ'' states are beginning to open new possibilities for how quarks can interact and bind. Detailed studies of their decays are underway in many facilities like the BES detector which has collected a over 4 fb-1 of data at energies between 4.01 to 4.6 GeV to study decays of Y(4260). While the nature of the Y(4260) is still unknown two particularly important decay channels to study would be radiative decays to ηc and χc 0, because their branching fraction ratio could be compared to existing E1/M1 branching fractions of conventional charmonium and to lattice qcd predictions. The prospects for measuring such transitions using data collected with the BES detector will be presented.

  20. Resolution of Transverse Electron Beam Measurements using Optical Transition Radiation

    SciTech Connect

    Ischebeck, Rasmus; Decker, Franz-Josef; Hogan, Mark; Iverson, Richard H.; Krejcik, Patrick; Lincoln, Melissa; Siemann, Robert H.; Walz, Dieter; Clayton, Chris E.; Huang, Chengkun; Lu, Wei; Deng, Suzhi; Oz, Erdem; /Southern California U.

    2005-06-22

    In the plasma wakefield acceleration experiment E-167, optical transition radiation is used to measure the transverse profile of the electron bunches before and after the plasma acceleration. The distribution of the electric field from a single electron does not give a point-like distribution on the detector, but has a certain extension. Additionally, the resolution of the imaging system is affected by aberrations. The transverse profile of the bunch is thus convolved with a point spread function (PSF). Algorithms that deconvolve the image can help to improve the resolution. Imaged test patterns are used to determine the modulation transfer function of the lens. From this, the PSF can be reconstructed. The Lucy-Richardson algorithm is used to deconvolute this PSF from test images.

  1. Exotic and excited-state radiative transitions in charmonium from lattice QCD

    DOE PAGES

    Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.

    2009-05-01

    We compute, for the first time using lattice QCD methods, radiative transition rates involving excited charmonium states, states of high spin and exotics. Utilizing a large basis of interpolating fields we are able to project out various excited state contributions to three-point correlators computed on quenched anisotropic lattices. In the first lattice QCD calculation of the exoticmore » $$1^{-+}$$ $$\\eta_{c1}$$ radiative decay, we find a large partial width $$\\Gamma(\\eta_{c1} \\to J/\\psi \\gamma) \\sim 100 \\,\\mathrm{keV}$$. We find clear signals for electric dipole and magnetic quadrupole transition form factors in $$\\chi_{c2} \\to J/\\psi \\gamma$$, calculated for the first time in this framework, and study transitions involving excited $$\\psi$$ and $$\\chi_{c1,2}$$ states. We calculate hindered magnetic dipole transition widths without the sensitivity to assumptions made in model studies and find statistically significant signals, including a non-exotic vector hybrid candidate $Y_{\\mathrm{hyb?}} \\to \\et« less

  2. Exotic and excited-state radiative transitions in charmonium from lattice QCD

    SciTech Connect

    Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.

    2009-05-01

    We compute, for the first time using lattice QCD methods, radiative transition rates involving excited charmonium states, states of high spin and exotics. Utilizing a large basis of interpolating fields we are able to project out various excited state contributions to three-point correlators computed on quenched anisotropic lattices. In the first lattice QCD calculation of the exotic $1^{-+}$ $\\eta_{c1}$ radiative decay, we find a large partial width $\\Gamma(\\eta_{c1} \\to J/\\psi \\gamma) \\sim 100 \\,\\mathrm{keV}$. We find clear signals for electric dipole and magnetic quadrupole transition form factors in $\\chi_{c2} \\to J/\\psi \\gamma$, calculated for the first time in this framework, and study transitions involving excited $\\psi$ and $\\chi_{c1,2}$ states. We calculate hindered magnetic dipole transition widths without the sensitivity to assumptions made in model studies and find statistically significant signals, including a non-exotic vector hybrid candidate $Y_{\\mathrm{hyb?}} \\to \\et

  3. Effective transition rates for epitaxial growth using fast modulation

    NASA Astrophysics Data System (ADS)

    Gallivan, Martha A.; Goodwin, David G.; Murray, Richard M.

    2004-07-01

    Thin-film deposition is an industrially important process that is highly dependent on the processing conditions. Most films are grown under constant conditions, but a few studies show that modified properties may be obtained with periodic inputs. However, assessing the effects of modulation experimentally becomes impractical with increasing material complexity. Here we consider periodic conditions in which the period is short relative to the time scales of growth. We analyze a stochastic model of thin-film growth, computing effective transition rates associated with rapid periodic process parameters. Combinations of effective rates may exist that are not attainable under steady conditions, potentially enabling new film properties. An algorithm is presented to construct the periodic input for a desired set of effective transition rates. These ideas are demonstrated in three simple examples using kinetic Monte Carlo simulations of epitaxial growth.

  4. Radiation rate enhancement in multilayered photonic and plasmonic nanopillars

    NASA Astrophysics Data System (ADS)

    Lawrence, Nate; Dal Negro, Luca

    2013-03-01

    We have systematically studied arrays of multilayered nanopillars composed of both metal and dielectic materials and shown that they can be used to enhance the radiative properties of active materials through modification of the local density of states (LDOS). Using an extension of the multipolar expansion method in two dimensions, we are able to calculate modifications in the radiation rate of emitters and power radiated to the far field. We show multi-resonant confinement of light to sub-wavelength gap regions inside nanopillars composed of alternating layers of metal and dielectric materials, forming a circular metal-insulator-metal (MIM) device. Sub-wavelength light confinement of 1.55 μm radiation is also demonstrated in purely dielectric nanopillars with reduced optical losses using alternating layers of high and low refractive index materials. In both cases, we find that the LDOS can be strongly increased, modifying the radiative rate and the internal quantum efficiency of emitters. Using top-down electron beam lithography, reactive ion etching and sputtering deposition we have created for the first time high-aspect ratio, light emitting, multilayered nanopillar structures consisting of alternating Si and Er:SiNx layers. Using dark-field scattering and photoluminescence decay spectroscopy we have experimentally characterized the fabricated nanostructures and demonstrated ability to control their radiation properties. These results are important to enable novel Si-based optical cavities and light emitting structures with nanoscale light confinement for optical communications and sensing.

  5. Historical mutation rates predict susceptibility to radiation in Chernobyl birds.

    PubMed

    Møller, A P; Erritzøe, J; Karadas, F; Mousseau, T A

    2010-10-01

    Extreme environmental perturbations are rare, but may have important evolutionary consequences. Responses to current perturbations may provide important information about the ability of living organisms to cope with similar conditions in the evolutionary past. Radioactive contamination from Chernobyl constitutes one such extreme perturbation, with significant but highly variable impact on local population density and mutation rates of different species of animals and plants. We explicitly tested the hypothesis that species with strong impacts of radiation on abundance were those with high rates of historical mutation accumulation as reflected by cytochrome b mitochondrial DNA base-pair substitution rates during past environmental perturbations. Using a dataset of 32 species of birds, we show higher historical mitochondrial substitution rates in species with the strongest negative impact of local levels of radiation on local population density. These effects were robust to different estimates of impact of radiation on abundance, weighting of estimates of abundance by sample size, statistical control for similarity in the response among species because of common phylogenetic descent, and effects of population size and longevity. Therefore, species that respond strongly to the impact of radiation from Chernobyl are also the species that in the past have been most susceptible to factors that have caused high substitution rates in mitochondrial DNA. © 2010 The Authors. Journal Compilation © 2010 European Society For Evolutionary Biology.

  6. Posture sway and the transition rate for a fall

    NASA Astrophysics Data System (ADS)

    Koleva, Radostina; Widom, A.; Garelick, D.; Harris, Meredith

    2001-04-01

    Postural body sway displacements for quiet standing subjects (measured with a new ultrasonic device) are reported. Two of the well-known strategies for balancing, namely ankle and hip movements, were probed. The data are modeled using a Fokker-Planck-Langevin stochastic theory. Both analytic and computer simulation techniques are employed. The Kramers transition rate for a fall is expressed as a function of experimental parameters. The root mean square velocity is especially important for determining the fall probability.

  7. Collective firm bankruptcies and phase transition in rating dynamics

    NASA Astrophysics Data System (ADS)

    Sieczka, P.; Hołyst, J. A.

    2009-10-01

    We present a simple model of firm rating evolution. We consider two sources of defaults: individual dynamics of economic development and Potts-like interactions between firms. We show that such a defined model leads to phase transition, which results in collective defaults. The existence of the collective phase depends on the mean interaction strength. For small interaction strength parameters, there are many independent bankruptcies of individual companies. For large parameters, there are giant collective defaults of firm clusters. In the case when the individual firm dynamics favors dumping of rating changes, there is an optimal strength of the firm's interactions from the systemic risk point of view. in here

  8. Reducing sojourn points from recurrence plots to improve transition detection: Application to fetal heart rate transitions.

    PubMed

    Zaylaa, Amira; Charara, Jamal; Girault, Jean-Marc

    2015-08-01

    The analysis of biomedical signals demonstrating complexity through recurrence plots is challenging. Quantification of recurrences is often biased by sojourn points that hide dynamic transitions. To overcome this problem, time series have previously been embedded at high dimensions. However, no one has quantified the elimination of sojourn points and rate of detection, nor the enhancement of transition detection has been investigated. This paper reports our on-going efforts to improve the detection of dynamic transitions from logistic maps and fetal hearts by reducing sojourn points. Three signal-based recurrence plots were developed, i.e. embedded with specific settings, derivative-based and m-time pattern. Determinism, cross-determinism and percentage of reduced sojourn points were computed to detect transitions. For logistic maps, an increase of 50% and 34.3% in sensitivity of detection over alternatives was achieved by m-time pattern and embedded recurrence plots with specific settings, respectively, and with a 100% specificity. For fetal heart rates, embedded recurrence plots with specific settings provided the best performance, followed by derivative-based recurrence plot, then unembedded recurrence plot using the determinism parameter. The relative errors between healthy and distressed fetuses were 153%, 95% and 91%. More than 50% of sojourn points were eliminated, allowing better detection of heart transitions triggered by gaseous exchange factors. This could be significant in improving the diagnosis of fetal state. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Excitation rate coefficients and line ratios for the optical and ultraviolet transitions in S II

    NASA Technical Reports Server (NTRS)

    Cai, Wei; Pradhan, Anil K.

    1993-01-01

    New calculations are reported for electron excitation collision strengths, rate coefficients, transition probabilities, and line ratios for the astrophysically important optical and UV lines in S II. The collision strengths are calculated in the close coupling approximation using the R-matrix method. The present calculations are more extensive than previous ones, including all transitions among the 12 lowest LS terms and the corresponding 28 fine-structure levels in the collisional-radiative model for S II. While the present rate coefficients for electron impact excitation are within 10-30 percent of the previous values for the low-lying optical transitions employed as density diagnostics of H II regions and nebulae, the excitation rates for the UV transitions 4S super 0 sub 3/2 - 4Psub 1/2,3/2,5/2 differ significantly from earlier calculations, by up to factor of 2. We describe temperature and density sensitive flux ratios for a number of UV lines. The present UV results are likely to be of interest in a more accurate interpretation of S II emission from the Io plasma torus in the magnetosphere of Jupiter, as well as other UV sources observed from the IUE, ASTRO 1, and the HST.

  10. Radiative lifetimes, branching rations, and absolute transition probabilities in Cr II and Zn II

    NASA Technical Reports Server (NTRS)

    Bergeson, S. D.; Lawler, J. E.

    1993-01-01

    New absolute atomic transition probability measurements are reported for 12 transitions in Cr II and two transitions in Zn II. These transition probabilities are determined by combining branching ratios measured by classical techniques and radiative lifetimes measured by time-resolved laser-induced fluorescence. The measurements are compared with branching fractions, radiative lifetimes, and transition probabilities in the literature. The 206 nm resonance multiplets in Cr II and Zn II are included in this work. These multiplets are very useful in determining the distribution of the elements in the gas versus grain phases in the interstellar medium.

  11. Radiological mapping of Kelantan, Malaysia, using terrestrial radiation dose rate.

    PubMed

    Garba, Nuraddeen Nasiru; Ramli, Ahmad Termizi; Saleh, Muneer Aziz; Sanusi, Syazwan Mohd; Gabdo, Hamman Tukur

    2016-06-01

    Measurements of the environmental terrestrial gamma radiation dose rate (TGRD) in each district of Kelantan state, Malaysia, were carried out using a portable hand-held radiation survey meter and global positioning system. The measurements were done based on geology and soil types of the area. The mean TGRD was found to be 209 nGy h(-1). Few areas of relatively enhanced activity were observed in Pasir Mas, Tanah Merah and Jeli districts, which have a mean TGRD between 300 and 500 nGy h(-1). An isodose map of the area was produced using ArcGIS software version 9.3.

  12. Dielectronic recombination rates, ionization equilibrium, and radiative emission rates for calcium and nickel ions in low-density high-temperature plasmas

    NASA Technical Reports Server (NTRS)

    Jacobs, V. L.; Davis, J.; Rogerson, J. E.; Blaha, M.; Cain, J.; Davis, M.

    1980-01-01

    The total dielectronic recombination rates for Ca and Ni ions were calculated taking into account autoionization to excited states of the recombining ion and stabilizing radiative transitions of the recombining electron. Radiative transitions of the recombining ion are found to be the dominant stabilizing processes, and the relative importance of Delta n = 0 and Delta n not equal to 0 transitions in the relevant temperature region is determined for each ion. The relative importance of the Delta n = 0 and Delta n not equal to 0 contributions is significantly altered for some ions by the inclusion of autoionization to excited levels. The relative abundance of the various ionization stages has been determined by using a corona equilibrium model in which collisional ionization and inner-shell excitation followed by autoionization are balanced by direct radiative and dielectronic recombination.

  13. Radiative transitions in InGaN quantum-well structures

    SciTech Connect

    Shapiro, Noad Asaf

    2002-01-01

    energy is interpreted in terms of a newly introduced parameter Lr, which can be regarded as the effective separation of electrons and holes participating in the luminescence transition. Strong carrier separation due to the built-in electric field usually results in a blueshift and Lr close to the QW width, Lw, whereas weak carrier separation usually can be a redshift. The carrier lifetime decreases with applied strain, indicating a reduction of the effective electron-hole (e-h) separation achieved by the strain-induced field-reduction in the well. This method is used to evaluate the effective e-h separation in several structures with varying QW thickness, indium concentration, and doping. Lr increases with QW thickness, decreases with indium content, and decreases with heavy doping in the active region. The decrease associated with indium content might be due either to an increase of ''carrier trapping'' in indium-rich nano-clusters or to an effective reduction of the QW thickness due to interface diffusion. The decrease of Lr associated with heavy doping is probably due to quenching of the electric field by the free carriers. The results also show that despite the reduced radiative transition rate associated with the carrier separation, the structures still exhibit efficient luminescence behavior and a low non-radiative recombination rate. This suggests that while the carriers are separated along the direction of the electric field, they are localized in the perpendicular direction such that they are not interacting with non-radiative centers associated with the high density of threading dislocations in the structure.

  14. Generation and Use of Coherent Transition Radiation from Short Electron Bunches

    SciTech Connect

    Settakorn, Chitrlada

    2001-08-28

    When accelerated, an electron bunch emits coherent radiation at wavelength longer than or comparable to the bunch length. The coherent radiation intensity scales with the square of the number of electron per bunch and its radiation spectrum is determined by the Fourier Transform of the electron bunch distribution squared. At the SUNSHINE (Stanford University Short Intense Electron Source) facility, electron bunches can be generated as short as {sigma}{sub z} = 36 {micro}m (120 femtosecond duration) and such bunches can emit coherent radiation in the far-infrared. Since a typical number for the electron population in a bunch is 10{sup 8}-10{sup 9}, the coherent radiation intensity is much higher than that of incoherent radiation as well as that of a conventional far-infrared radiation source. This concentrates on coherent transition and diffraction radiation from short electron bunches as a potential high intensity far-infrared radiation source and for sub-picosecond electron bunch length measurements. Coherent transition radiation generated from a 25 MeV beam at a vacuum-metal interface is characterized. Such a high intensity radiation source allows far-infrared spectroscopy to be conducted conveniently with a Michelson interferometer and a room temperature detector. Measurements of the refractive index of silicon are described to demonstrate the possibilities of far-infrared spectroscopy using coherent transition radiation Coherent diffraction radiation, which is closely related to coherent transition radiation, can be considered as another potential FIR radiation source. Since the perturbation by the radiation generation to the electron beam is relatively small, it has the advantage of being a nondestructive radiation source.

  15. The rate constant for radiative association of HF: Comparing quantum and classical dynamics

    SciTech Connect

    Gustafsson, Magnus Monge-Palacios, M.; Nyman, Gunnar

    2014-05-14

    Radiative association for the formation of hydrogen fluoride through the A{sup 1}Π → X{sup 1}Σ{sup +} and X{sup 1}Σ{sup +} → X{sup 1}Σ{sup +} transitions is studied using quantum and classical dynamics. The total thermal rate constant is obtained for temperatures from 10 K to 20 000 K. Agreement between semiclassical and quantum approaches is observed for the A{sup 1}Π → X{sup 1}Σ{sup +} rate constant above 2000 K. The agreement is explained by the fact that the corresponding cross section is free of resonances for this system. At temperatures below 2000 K we improve the agreement by implementing a simplified semiclassical expression for the rate constant, which includes a quantum corrected pair distribution. The rate coefficient for the X{sup 1}Σ{sup +} → X{sup 1}Σ{sup +} transition is calculated using Breit–Wigner theory and a classical formula for the resonance and direct contributions, respectively. In comparison with quantum calculations the classical formula appears to overestimate the direct contribution to the rate constant by about 12% for this transition. Below about 450 K the resonance contribution is larger than the direct, and above that temperature the opposite holds. The biggest contribution from resonances is at the lowest temperature in the study, 10 K, where it is more than four times larger than the direct. Below 1800 K the radiative association rate constant due to X{sup 1}Σ{sup +} → X{sup 1}Σ{sup +} transitions dominates over A{sup 1}Π → X{sup 1}Σ{sup +}, while above that temperature the situation is the opposite.

  16. Fine-structure energy levels, radiative rates and lifetimes in Si-like nickel

    NASA Astrophysics Data System (ADS)

    Gupta, G. P.; Msezane, A. Z.

    2012-07-01

    Large scale CIV3 calculations of excitation energies from ground state as well as of oscillator strengths and radiative decay rates for all electric-dipole-allowed and intercombination transitions among the fine-structure levels of the terms belonging to the (1s22s22p6)3s23p2, 3s3p3, 3p4, 3s23p3d, 3s23p4s, 3s23p4p, 3s23p4d and 3s23p4f configurations of Ni XV, are performed using very extensive configuration-interaction wave functions. The relativistic effects in intermediate coupling are incorporated by means of the Breit-Pauli Hamiltonian. In order to keep our calculated energy splittings as close as possible to the National Institute of Standard and Technology (NIST) values, we have made small adjustments to the diagonal elements of the Hamiltonian matrices. Our calculated excitation energies, including their ordering, are in excellent agreement with the available NIST results. From our radiative decay rates we have also calculated radiative lifetimes of the fine-structure levels. It is noted that our calculated radiative rates show significant disagreement (23-30%) with those calculated by Ishikawa and Vilkas (2002 Phys. Scr. 65 219) for the transitions involving the 3s3p3(5S2) level. For this high spin level 3s3p3(5S2) our calculated lifetime is found to be in excellent agreement with the experimental value of Träbert et al (1989 Z. Phys. D 11 207). In this calculation, we also predict many additional new and accurate data for various optically allowed and intercombination transitions to complete the void in the existing data.

  17. Strong effects of ionizing radiation from Chernobyl on mutation rates

    NASA Astrophysics Data System (ADS)

    Møller, Anders Pape; Mousseau, Timothy A.

    2015-02-01

    In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species. Overall effect size of radiation on mutation rates estimated as Pearson's product-moment correlation coefficient was very large (E = 0.67; 95% confidence intervals (CI) 0.59 to 0.73), accounting for 44.3% of the total variance in an unstructured random-effects model. Fail-safe calculations reflecting the number of unpublished null results needed to eliminate this average effect size showed the extreme robustness of this finding (Rosenberg's method: 4135 at p = 0.05). Indirect tests did not provide any evidence of publication bias. The effect of radiation on mutations varied among taxa, with plants showing a larger effect than animals. Humans were shown to have intermediate sensitivity of mutations to radiation compared to other species. Effect size did not decrease over time, providing no evidence for an improvement in environmental conditions. The surprisingly high mean effect size suggests a strong impact of radioactive contamination on individual fitness in current and future generations, with potentially significant population-level consequences, even beyond the area contaminated with radioactive material.

  18. Strong effects of ionizing radiation from Chernobyl on mutation rates

    PubMed Central

    Møller, Anders Pape; Mousseau, Timothy A.

    2015-01-01

    In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species. Overall effect size of radiation on mutation rates estimated as Pearson's product-moment correlation coefficient was very large (E = 0.67; 95% confidence intervals (CI) 0.59 to 0.73), accounting for 44.3% of the total variance in an unstructured random-effects model. Fail-safe calculations reflecting the number of unpublished null results needed to eliminate this average effect size showed the extreme robustness of this finding (Rosenberg's method: 4135 at p = 0.05). Indirect tests did not provide any evidence of publication bias. The effect of radiation on mutations varied among taxa, with plants showing a larger effect than animals. Humans were shown to have intermediate sensitivity of mutations to radiation compared to other species. Effect size did not decrease over time, providing no evidence for an improvement in environmental conditions. The surprisingly high mean effect size suggests a strong impact of radioactive contamination on individual fitness in current and future generations, with potentially significant population-level consequences, even beyond the area contaminated with radioactive material. PMID:25666381

  19. Strong effects of ionizing radiation from Chernobyl on mutation rates.

    PubMed

    Møller, Anders Pape; Mousseau, Timothy A

    2015-02-10

    In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species. Overall effect size of radiation on mutation rates estimated as Pearson's product-moment correlation coefficient was very large (E = 0.67; 95% confidence intervals (CI) 0.59 to 0.73), accounting for 44.3% of the total variance in an unstructured random-effects model. Fail-safe calculations reflecting the number of unpublished null results needed to eliminate this average effect size showed the extreme robustness of this finding (Rosenberg's method: 4135 at p = 0.05). Indirect tests did not provide any evidence of publication bias. The effect of radiation on mutations varied among taxa, with plants showing a larger effect than animals. Humans were shown to have intermediate sensitivity of mutations to radiation compared to other species. Effect size did not decrease over time, providing no evidence for an improvement in environmental conditions. The surprisingly high mean effect size suggests a strong impact of radioactive contamination on individual fitness in current and future generations, with potentially significant population-level consequences, even beyond the area contaminated with radioactive material.

  20. Interplay of radiative and nonradiative transitions in surface hopping with radiation-molecule interactions

    SciTech Connect

    Bajo, Juan José; Granucci, Giovanni Persico, Maurizio

    2014-01-28

    We implemented a method for the treatment of field induced transitions in trajectory surface hopping simulations, in the framework of the local diabatization scheme, especially suited for on-the-fly dynamics. The method is applied to a simple one-dimensional model with an avoided crossing and compared with quantum wavepacket dynamics. The results show the importance of introducing a proper decoherence correction to surface hopping, in order to obtain meaningful results. Also the energy conservation policy of standard surface hopping must be revised: in fact, the quantum wavepacket energetics is well reproduced if energy absorption/emission is allowed for in the hops determined by radiation-molecule coupling. To our knowledge, this is the first time the issues of decoherence and energy conservation have been analyzed in depth to devise a mixed quantum-classical method for dynamics with molecule-field interactions.

  1. Compensated count-rate circuit for radiation survey meter

    DOEpatents

    Todd, Richard A.

    1981-01-01

    A count-rate compensating circuit is provided which may be used in a portable Geiger-Mueller (G-M) survey meter to ideally compensate for counting loss errors in the G-M tube detector. In a G-M survey meter, wherein the pulse rate from the G-M tube is converted into a pulse rate current applied to a current meter calibrated to indicate dose rate, the compensated circuit generates and controls a reference voltage in response to the rate of pulses from the detector. This reference voltage is gated to the current-generating circuit at a rate identical to the rate of pulses coming from the detector so that the current flowing through the meter is varied in accordance with both the frequency and amplitude of the reference voltage pulses applied thereto so that the count rate is compensated ideally to indicate a true count rate within 1% up to a 50% duty cycle for the detector. A positive feedback circuit is used to control the reference voltage so that the meter output tracks true count rate indicative of the radiation dose rate.

  2. Compensated count-rate circuit for radiation survey meter

    DOEpatents

    Todd, R.A.

    1980-05-12

    A count-rate compensating circuit is provided which may be used in a portable Geiger-Mueller (G-M) survey meter to ideally compensate for couting loss errors in the G-M tube detector. In a G-M survey meter, wherein the pulse rate from the G-M tube is converted into a pulse rate current applied to a current meter calibrated to indicate dose rate, the compensation circuit generates and controls a reference voltage in response to the rate of pulses from the detector. This reference voltage is gated to the current-generating circuit at a rate identical to the rate of pulses coming from the detector so that the current flowing through the meter is varied in accordance with both the frequency and amplitude of the reference voltage pulses applied thereto so that the count rate is compensated ideally to indicate a true count rate within 1% up to a 50% duty cycle for the detector. A positive feedback circuit is used to control the reference voltage so that the meter output tracks true count rate indicative of the radiation dose rate.

  3. Radiative heating and cooling rates in the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Gille, John C.; Lyjak, Lawrence V.

    1986-01-01

    One of the limitations to the accurate calculation of radiative heating and cooling rates in the stratosphere and mesosphere has been the lack of accurate data on the atmospheric temperature and composition. Data from the LIMS experiment on Nimbus-7 has been extended to the South Pole with the aid of other observations. The data have been used as input to codes developed by Ramanathan and Dickinson to calculate the individual components and the net radiative heating rates from 100-0.1 mb. Solar heating due to ozone, nitrogen dioxide, carbon dioxide, water vapor and oxygen is shown to be nearly balanced by cooling in the thermal infrared spectral region due to carbon dioxide, ozone and water vapor. In the lower stratosphere, infrared transfer by ozone leads to heating that is sensitive to the distribution of tropospheric ozone, clouds and water vapor. The heating and cooling rates are adjusted slightly in order to satisfy the global mass balance. The results are in qualitative agreement with earlier calculations, but show additional detail. There is as strong temporal and vertical variation of cooling in the tropics. Radiative relaxation times are as short as 7 days or less at the stratopause.

  4. Cloud Properties and Radiative Heating Rates for TWP

    DOE Data Explorer

    Comstock, Jennifer

    2013-11-07

    A cloud properties and radiative heating rates dataset is presented where cloud properties retrieved using lidar and radar observations are input into a radiative transfer model to compute radiative fluxes and heating rates at three ARM sites located in the Tropical Western Pacific (TWP) region. The cloud properties retrieval is a conditional retrieval that applies various retrieval techniques depending on the available data, that is if lidar, radar or both instruments detect cloud. This Combined Remote Sensor Retrieval Algorithm (CombRet) produces vertical profiles of liquid or ice water content (LWC or IWC), droplet effective radius (re), ice crystal generalized effective size (Dge), cloud phase, and cloud boundaries. The algorithm was compared with 3 other independent algorithms to help estimate the uncertainty in the cloud properties, fluxes, and heating rates (Comstock et al. 2013). The dataset is provided at 2 min temporal and 90 m vertical resolution. The current dataset is applied to time periods when the MMCR (Millimeter Cloud Radar) version of the ARSCL (Active Remotely-Sensed Cloud Locations) Value Added Product (VAP) is available. The MERGESONDE VAP is utilized where temperature and humidity profiles are required. Future additions to this dataset will utilize the new KAZR instrument and its associated VAPs.

  5. Biotic turnover rates during the Pleistocene-Holocene transition

    NASA Astrophysics Data System (ADS)

    Stivrins, Normunds; Soininen, Janne; Amon, Leeli; Fontana, Sonia L.; Gryguc, Gražyna; Heikkilä, Maija; Heiri, Oliver; Kisielienė, Dalia; Reitalu, Triin; Stančikaitė, Miglė; Veski, Siim; Seppä, Heikki

    2016-11-01

    The Northern Hemisphere is currently warming at the rate which is unprecedented during the Holocene. Quantitative palaeoclimatic records show that the most recent time in the geological history with comparable warming rates was during the Pleistocene-Holocene transition (PHT) about 14,000 to 11,000 years ago. To better understand the biotic response to rapid temperature change, we explore the community turnover rates during the PHT by focusing on the Baltic region in the southeastern sector of the Scandinavian Ice Sheet, where an exceptionally dense network on microfossil and macrofossil data that reflect the biotic community history are available. We further use a composite chironomid-based summer temperature reconstruction compiled specifically for our study region to calculate the rate of temperature change during the PHT. The fastest biotic turnover in the terrestrial and aquatic communities occurred during the Younger Dryas-Holocene shift at 11,700 years ago. This general shift in species composition was accompanied by regional extinctions, including disappearance of mammoth (Mammuthus primigenius) and reindeer (Rangifer tarandus) and many arctic-alpine plant taxa, such as Dryas octopetala, Salix polaris and Saxifraga aizoides, from the region. This rapid biotic turnover rate occurred when the rate of warming was 0.17 °C/decade, thus slightly lower than the current Northern Hemisphere warming of 0.2 °C/decade. We therefore conclude that the Younger Dryas-Holocene shift with its rapid turnover rates and associated regional extinctions represents an important palaeoanalogue to the current high latitude warming and gives insights about the probable future turnover rates and patterns of the terrestrial and aquatic ecosystem change.

  6. SEAC4RS Aerosol Radiative Effects and Heating Rates

    NASA Astrophysics Data System (ADS)

    Cochrane, S.; Schmidt, S.; Redemann, J.; Hair, J. W.; Ferrare, R. A.; Segal-Rosenhaimer, M.; LeBlanc, S. E.

    2015-12-01

    We will present (a) aerosol optical properties, (b) aerosol radiative forcing, (c) aerosol and gas absorption and heating rates, and (d) spectral surface albedo for cases from August 19th and 26th of the SEAC4RS mission. This analysis is based on irradiance data from the Solar Spectral Flux Radiometer (SSFR), spectral aerosol optical depth from the Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR), and extinction profiles from the DIAL/High Spectral Resolution Lidar (HSRL). We derive spectrally resolved values of single scattering albedo, asymmetry parameter, and surface albedo from the data, and determine profiles of absorption and heating rate segregated by absorber (aerosol and gas).

  7. Rate constants for the formation of SiO by radiative association

    NASA Astrophysics Data System (ADS)

    Cairnie, M.; Forrey, R. C.; Babb, J. F.; Stancil, P. C.; McLaughlin, B. M.

    2017-10-01

    Accurate molecular data for the low-lying states of SiO are computed and used to calculate rate constants for radiative association (RA) of Si and O. Einstein A-coefficients are also calculated for transitions between all of the bound and quasi-bound levels for each molecular state. The radiative widths are used together with elastic tunnelling widths to define effective RA rate constants which include both direct and indirect (inverse pre-dissociation) formation processes. The indirect process is evaluated for two kinetic models which represent limiting cases for astrophysical environments. The first case scenario assumes an equilibrium distribution of quasi-bound states and would be applicable whenever collisional and/or radiative excitation mechanisms are able to maintain the population. The second case scenario assumes that no excitation mechanisms are available which corresponds to the limit of zero radiation temperature and zero atomic density. Rate constants for SiO formation in realistic astrophysical environments would presumably lie between these two limiting cases.

  8. The electron energy loss rate due to radiative recombination

    NASA Astrophysics Data System (ADS)

    Mao, Junjie; Kaastra, Jelle; Badnell, N. R.

    2017-02-01

    Context. For photoionized plasmas, electron energy loss rates due to radiative recombination (RR) are required for thermal equilibrium calculations, which assume a local balance between the energy gain and loss. While many calculations of total and/or partial RR rates are available from the literature, specific calculations of associated RR electron energy loss rates are lacking. Aims: Here we focus on electron energy loss rates due to radiative recombination of H-like to Ne-like ions for all the elements up to and including zinc (Z = 30), over a wide temperature range. Methods: We used the AUTOSTRUCTURE code to calculate the level-resolved photoionization cross section and modify the ADASRR code so that we can simultaneously obtain level-resolved RR rate coefficients and associated RR electron energy loss rate coefficients. We compared the total RR rates and electron energy loss rates of H i and He i with those found in the literature. Furthermore, we utilized and parameterized the weighted electron energy loss factors (dimensionless) to characterize total electron energy loss rates due to RR. Results: The RR electron energy loss data are archived according to the Atomic Data and Analysis Structure (ADAS) data class adf48. The RR electron energy loss data are also incorporated into the SPEX code for detailed modeling of photoionized plamsas. Full Tables 1 and 2 are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A10

  9. Reversed Cherenkov-Transition Radiation by a Charge Crossing a Left-Handed Medium Boundary

    SciTech Connect

    Galyamin, Sergey N.; Tyukhtin, Andrey V.; Kanareykin, Alexey; Schoessow, Paul

    2009-11-06

    We analyze the radiation from a charged particle crossing the boundary between an ordinary medium and a 'left-handed' metamaterial. We obtain exact and approximate expressions for the field components and develop algorithms for their computation. The spatial radiation in this system can be separated into three distinct components, corresponding to ordinary transition radiation having a relatively large magnitude, Cherenkov radiation, and reversed Cherenkov-transition radiation (RCTR). The last one is explained by reflection and refraction of reversed Cherenkov radiation at the interface. Conditions for generating of RCTR are obtained. We note properties of this radiation that have potential applications in the detection of charged particles and accelerator beams and for the characterization of metamaterial macroscopic parameters (epsilon, mu).

  10. Theory of coherent transition radiation generated at a plasma-vacuum interface

    SciTech Connect

    Schroeder, Carl B.; Esarey, Eric; van Tilborg, Jeroen; Leemans, Wim P.

    2003-06-26

    Transition radiation generated by an electron beam, produced by a laser wakefield accelerator operating in the self-modulated regime, crossing the plasma-vacuum boundary is considered. The angular distributions and spectra are calculated for both the incoherent and coherent radiation. The effects of the longitudinal and transverse momentum distributions on the differential energy spectra are examined. Diffraction radiation from the finite transverse extent of the plasma is considered and shown to strongly modify the spectra and energy radiated for long wavelength radiation. This method of transition radiation generation has the capability of producing high peak power THz radiation, of order 100 (mu)J/pulse at the plasma-vacuum interface, which is several orders of magnitude beyond current state-of-the-art THz sources.

  11. Atomic data from the Iron Project. XVII. Radiative transition probabilities for dipole allowed and forbidden transitions in Fe III.

    NASA Astrophysics Data System (ADS)

    Nahar, S. N.; Pradhan, A. K.

    1996-11-01

    Transition probabilities are obtained for both the dipole allowed (E1) fine structure transitions and the forbidden electric quadrupole and magnetic dipole (E2, M1) transitions in Fe III. For the E1 transitions, ab initio calculations in the close coupling (CC) approximation using the R-matrix method are carried out in LS coupling with a 49-term eigenfunction expansion for Fe IV. The fine structure components are obtained through algebraic transformation of the LS line strengths, and the oscillator strengths and A-coefficients are computed using spectroscopic energies of the observed levels. Radiative transition probabilities for 9797 fine structure E1 transitions corresponding to 1408 LS multiplets among 200 bound states of Fe III are reported. Forbidden E2 and M1 transition probabilities are computed for 362 transitions among the 34 fine structure levels of all 16 LS terms dominated by the 3d^6^ configuration using optimised configuration-interaction wavefunctions from the SUPERSTRUCTURE program in the Breit-Pauli approximation. Comparison of the present results is made with previous calculations and significant differences are found. Theoretical line ratios computed using the present E2 and M1 A-coefficients show better agreement with observations for some prominent Fe III lines in the infra-red than those using the earlier data by Garstang (1957MNRAS.117..393G). This work is carried out as part of the Iron Project to obtain accurate radiative and collisional data for the Iron group elements.

  12. Spin-flip processes and radiative decay of dark intravalley excitons in transition metal dichalcogenide monolayers

    NASA Astrophysics Data System (ADS)

    Slobodeniuk, A. O.; Basko, D. M.

    2016-09-01

    We perform a theoretical study of radiative decay of dark intravalley excitons in transition metal dichalcogenide monolayers. This decay necessarily involves an electronic spin flip. The intrinsic decay mechanism due to interband spin-flip dipole moment perpendicular to the monolayer plane, gives a rate about 100-1000 times smaller than that of bright excitons. However, we find that this mechanism also introduces an energy splitting due to a local field effect, and the whole oscillator strength is contained in the higher-energy component, while the lowest-energy state remains dark and needs an extrinsic spin-flip mechanism for the decay. Rashba effect due to a perpendicular electric field or a dielectric substrate, gives a negligible radiative decay rate (about 107 times slower than that of bright excitons). Spin flip due to Zeeman effect in a sufficiently strong in-plane magnetic field can give a decay rate comparable to that due to the intrinsic interband spin-flip dipole.

  13. Rates of dinosaur limb evolution provide evidence for exceptional radiation in Mesozoic birds.

    PubMed

    Benson, Roger B J; Choiniere, Jonah N

    2013-10-07

    Birds are the most diverse living tetrapod group and are a model of large-scale adaptive radiation. Neontological studies suggest a radiation within the avian crown group, long after the origin of flight. However, deep time patterns of bird evolution remain obscure because only limited fossil data have been considered. We analyse cladogenesis and limb evolution on the entire tree of Mesozoic theropods, documenting the dinosaur-bird transition and immediate origins of powered flight. Mesozoic birds inherited constraints on forelimb evolution from non-flying ancestors, and species diversification rates did not accelerate in the earliest flying taxa. However, Early Cretaceous short-tailed birds exhibit both phenotypic release of the hindlimb and increased diversification rates, unparalleled in magnitude at any other time in the first 155 Myr of theropod evolution. Thus, a Cretaceous adaptive radiation of stem-group birds was enabled by restructuring of the terrestrial locomotor module, which represents a key innovation. Our results suggest two phases of radiation in Avialae: with the Cretaceous diversification overwritten by extinctions of stem-group birds at the Cretaceous-Palaeogene boundary, and subsequent diversification of the crown group. Our findings illustrate the importance of fossil data for understanding the macroevolutionary processes generating modern biodiversity.

  14. Rates of dinosaur limb evolution provide evidence for exceptional radiation in Mesozoic birds

    PubMed Central

    Benson, Roger B. J.; Choiniere, Jonah N.

    2013-01-01

    Birds are the most diverse living tetrapod group and are a model of large-scale adaptive radiation. Neontological studies suggest a radiation within the avian crown group, long after the origin of flight. However, deep time patterns of bird evolution remain obscure because only limited fossil data have been considered. We analyse cladogenesis and limb evolution on the entire tree of Mesozoic theropods, documenting the dinosaur–bird transition and immediate origins of powered flight. Mesozoic birds inherited constraints on forelimb evolution from non-flying ancestors, and species diversification rates did not accelerate in the earliest flying taxa. However, Early Cretaceous short-tailed birds exhibit both phenotypic release of the hindlimb and increased diversification rates, unparalleled in magnitude at any other time in the first 155 Myr of theropod evolution. Thus, a Cretaceous adaptive radiation of stem-group birds was enabled by restructuring of the terrestrial locomotor module, which represents a key innovation. Our results suggest two phases of radiation in Avialae: with the Cretaceous diversification overwritten by extinctions of stem-group birds at the Cretaceous–Palaeogene boundary, and subsequent diversification of the crown group. Our findings illustrate the importance of fossil data for understanding the macroevolutionary processes generating modern biodiversity. PMID:23945695

  15. Measurements of the spectrum and energy dependence of X-ray transition radiation

    NASA Technical Reports Server (NTRS)

    Cherry, M. L.

    1978-01-01

    The results of experiments designed to test the theory of X-ray transition radiation and to verify the predicted dependence of the characteristic features of the radiation on the radiator dimensions are presented. The X-ray frequency spectrum produced by 5- to 9-GeV electrons over the range 4 to 30 keV was measured with a calibrated single-crystal Bragg spectrometer, and at frequencies up to 100 keV with an NaI scintillator. The interference pattern in the spectrum and the hardening of the radiation with increasing foil thickness are clearly observed. The energy dependence of the total transition-radiation intensity was studied using a radiator with large dimensions designed to yield energy-dependent signals at very high particle energies, up to E/mc-squared approximately equal to 100,000. The results are in good agreement with the theoretical predictions.

  16. Observation of fine structures in laser-driven electron beams using coherent transition radiation.

    PubMed

    Glinec, Y; Faure, J; Norlin, A; Pukhov, A; Malka, V

    2007-05-11

    We have measured the coherent optical transition radiation emitted by an electron beam from laser-plasma interaction. The measurement of the spectrum of the radiation reveals fine structures of the electron beam in the range 400-1000 nm. These structures are reproduced using an electron distribution from a 3D particle-in-cell simulation and are attributed to microbunching of the electron bunch due to its interaction with the laser field. When the radiator is placed closer to the interaction point, spectral oscillations have also been recorded, signature of the interference of the radiation produced by two electron bunches delayed by 74 fs. The second electron bunch duration is shown to be ultrashort to match the intensity level of the radiation. Whereas transition radiation was used at longer wavelengths in order to estimate the electron bunch length, this study focuses on the ultrashort structures of the electron beam.

  17. Strong Role of Non-stationary Accretion in Spectral Transitions of X-ray Binaries and Implications for Revealing the Accretion Geometry and Broadband Radiation Mechanisms

    NASA Astrophysics Data System (ADS)

    Yu, Wenfei; Yan, Zhen; Tang, Jing; Wu, Yuxiang

    Observations of spectral transitions from the hard state to the soft state in bright X-ray binaries show strong evidence that the rate-of-change of the mass accretion rate plays a dominant role in determining the luminosity at which the spectral transition occurs. This indicates that in many cases, especially accretion in transients during outbursts, the rate-of-change of the mass accretion rate is the primary parameter driving high energy phenomena. Although this goes beyond the scope of current stationary model of disk and jet, it tells us that it is the rate-of-change of the mass accretion rate that we need to trace observationally. Since state transition is a broadband phenomenon, multi-wavelength observations of spectral transitions of different rate-of-changes of mass accretion rate are expect to reveal the accretion geometry and broadband radiation mechanisms.

  18. Characteristic, parametric, and diffracted transition X-ray radiation for observation of accelerated particle beam profile

    NASA Astrophysics Data System (ADS)

    Chaikovska, I.; Chehab, R.; Artru, X.; Shchagin, A. V.

    2017-07-01

    The applicability of X-ray radiation for the observation of accelerated particle beam profiles is studied. Three types of quasi-monochromatic X-ray radiation excited by the particles in crystals are considered: characteristic X-ray radiation, parametric X-ray radiation, diffracted transition X-ray radiation. Radiation is collected at the right angle to the particle beam direction. It is show that the most intensive differential yield of X-ray radiation from Si crystal can be provided by characteristic radiation at incident electron energies up to tens MeV, by parametric radiation at incident electron energies from tens to hundreds MeV, by diffracted transition X-ray radiation at GeV and multi-GeV electron energies. Therefore these kinds of radiation are proposed for application to beam profile observation in the corresponding energy ranges of incident electrons. Some elements of X-ray optics for observation of the beam profile are discussed. The application of the DTR as a source of powerful tunable monochromatic linearly polarized X-ray beam excited by a multi-GeV electron beam on the crystal surface is proposed.

  19. Rates of morphological evolution in Captorhinidae: an adaptive radiation of Permian herbivores.

    PubMed

    Brocklehurst, Neil

    2017-01-01

    The evolution of herbivory in early tetrapods was crucial in the establishment of terrestrial ecosystems, although it is so far unclear what effect this innovation had on the macro-evolutionary patterns observed within this clade. The clades that entered this under-filled region of ecospace might be expected to have experienced an "adaptive radiation": an increase in rates of morphological evolution and speciation driven by the evolution of a key innovation. However such inferences are often circumstantial, being based on the coincidence of a rate shift with the origin of an evolutionary novelty. The conclusion of an adaptive radiation may be made more robust by examining the pattern of the evolutionary shift; if the evolutionary innovation coincides not only with a shift in rates of morphological evolution, but specifically in the morphological characteristics relevant to the ecological shift of interest, then one may more plausibly infer a causal relationship between the two. Here I examine the impact of diet evolution on rates of morphological change in one of the earliest tetrapod clades to evolve high-fibre herbivory: Captorhinidae. Using a method of calculating heterogeneity in rates of discrete character change across a phylogeny, it is shown that a significant increase in rates of evolution coincides with the transition to herbivory in captorhinids. The herbivorous captorhinids also exhibit greater morphological disparity than their faunivorous relatives, indicating more rapid exploration of new regions of morphospace. As well as an increase in rates of evolution, there is a shift in the regions of the skeleton undergoing the most change; the character changes in the herbivorous lineages are concentrated in the mandible and dentition. The fact that the increase in rates of evolution coincides with increased change in characters relating to food acquisition provides stronger evidence for a causal relationship between the herbivorous diet and the radiation

  20. Energy levels and transition rates for helium-like ions with Z = 10-36

    NASA Astrophysics Data System (ADS)

    Si, R.; Guo, X. L.; Wang, K.; Li, S.; Yan, J.; Chen, C. Y.; Brage, T.; Zou, Y. M.

    2016-08-01

    Aims: Helium-like ions provide an important X-ray spectral diagnostics in astrophysical and high-temperature fusion plasmas. An interpretation of the observed spectra provides information on temperature, density, and chemical compositions of the plasma. Such an analysis requires information for a wide range of atomic parameters, including energy levels and transition rates. Our aim is to provide a set of accurate energy levels and transition rates for helium-like ions with Z = 10-36. Methods: The second-order many-body perturbation theory (MBPT) was adopted in this paper. To support our MBPT results, we performed an independent calculation using the multiconfiguration Dirac-Hartree-Fock (MCDHF) method. Results: We provide accurate energies for the lowest singly excited 70 levels among 1snl(n ≤ 6,l ≤ (n-1)) configurations and the lowest doubly excited 250 levels arising from the K-vacancy 2ln'l'(n' ≤ 6,l' ≤ (n'-1)) configurations of helium-like ions with Z = 10-36. Wavelengths, transition rates, oscillator strengths, and line strengths are calculated for the E1, M1, E2, and M2 transitions among these levels. The radiative lifetimes are reported for all the calculated levels. Conclusions: Our MBPT results for singly excited n ≤ 2 levels show excellent agreement with other elaborate calculations, while those for singly excited n ≥ 3 and doubly excited levels show significant improvements over previous theoretical results. Our results will be very helpful for astrophysical line identification and plasma diagnostics. Full Tables 1 and 2 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A141

  1. Rapid calculation of radiative heating rates and photodissociation rates in inhomogeneous multiple scattering atmospheres

    NASA Technical Reports Server (NTRS)

    Toon, Owen B.; Mckay, C. P.; Ackerman, T. P.; Santhanam, K.

    1989-01-01

    The solution of the generalized two-stream approximation for radiative transfer in homogeneous multiple scattering atmospheres is extended to vertically inhomogeneous atmospheres in a manner which is numerically stable and computationally efficient. It is shown that solar energy deposition rates, photolysis rates, and infrared cooling rates all may be calculated with the simple modifications of a single algorithm. The accuracy of the algorithm is generally better than 10 percent, so that other uncertainties, such as in absorption coefficients, may often dominate the error in calculation of the quantities of interest to atmospheric studies.

  2. Some results of test beam studies of Transition Radiation Detector prototypes at CERN

    NASA Astrophysics Data System (ADS)

    Tikhomirov, V. O.; Brooks, T.; Joos, M.; Rembser, C.; Celebi, E.; Gurbuz, S.; Cetin, S. A.; Konovalov, S. P.; Zhukov, K.; Fillipov, K. A.; Romaniouk, A.; Smirnov, S. Yu; Teterin, P. E.; Vorobev, K. A.; Boldyrev, A. S.; Maevsky, A.; Derendarz, D.

    2017-01-01

    Operating conditions and challenging demands of present and future accelerator experiments result in new requirements on detector systems. There are many ongoing activities aimed to develop new technologies and to improve the properties of detectors based on existing technologies. Our work is dedicated to development of Transition Radiation Detectors (TRD) suitable for different applications. In this paper results obtained in beam tests at SPS accelerator at CERN with the TRD prototype based on straw technology are presented. TRD performance was studied as a function of thickness of the transition radiation radiator and working gas mixture pressure.

  3. Kinetic model of mass exchange with dynamic Arrhenius transition rates

    NASA Astrophysics Data System (ADS)

    Hristopulos, Dionissios T.; Muradova, Aliki

    2016-02-01

    We study a nonlinear kinetic model of mass exchange between interacting grains. The transition rates follow the Arrhenius equation with an activation energy that depends dynamically on the grain mass. We show that the activation parameter can be absorbed in the initial conditions for the grain masses, and that the total mass is conserved. We obtain numerical solutions of the coupled, nonlinear, ordinary differential equations of mass exchange for the two-grain system, and we compare them with approximate theoretical solutions in specific neighborhoods of the phase space. Using phase plane methods, we determine that the system exhibits regimes of diffusive and growth-decay (reverse diffusion) kinetics. The equilibrium states are determined by the mass equipartition and separation nullcline curves. If the transfer rates are perturbed by white noise, numerical simulations show that the system maintains the diffusive and growth-decay regimes; however, the noise can reverse the sign of equilibrium mass difference. Finally, we present theoretical analysis and numerical simulations of a system with many interacting grains. Diffusive and growth-decay regimes are established as well, but the approach to equilibrium is considerably slower. Potential applications of the mass exchange model involve coarse-graining during sintering and wealth exchange in econophysics.

  4. Radiative decay rates of impurity states in semiconductor nanocrystals

    NASA Astrophysics Data System (ADS)

    Turkov, Vadim K.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

    2015-10-01

    Doped semiconductor nanocrystals is a versatile material base for contemporary photonics and optoelectronics devices. Here, for the first time to the best of our knowledge, we theoretically calculate the radiative decay rates of the lowest-energy states of donor impurity in spherical nanocrystals made of four widely used semiconductors: ZnS, CdSe, Ge, and GaAs. The decay rates were shown to vary significantly with the nanocrystal radius, increasing by almost three orders of magnitude when the radius is reduced from 15 to 5 nm. Our results suggest that spontaneous emission may dominate the decay of impurity states at low temperatures, and should be taken into account in the design of advanced materials and devices based on doped semiconductor nanocrystals.

  5. Radiative decay rates of impurity states in semiconductor nanocrystals

    SciTech Connect

    Turkov, Vadim K.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

    2015-10-15

    Doped semiconductor nanocrystals is a versatile material base for contemporary photonics and optoelectronics devices. Here, for the first time to the best of our knowledge, we theoretically calculate the radiative decay rates of the lowest-energy states of donor impurity in spherical nanocrystals made of four widely used semiconductors: ZnS, CdSe, Ge, and GaAs. The decay rates were shown to vary significantly with the nanocrystal radius, increasing by almost three orders of magnitude when the radius is reduced from 15 to 5 nm. Our results suggest that spontaneous emission may dominate the decay of impurity states at low temperatures, and should be taken into account in the design of advanced materials and devices based on doped semiconductor nanocrystals.

  6. Observation of coherent transition radiation using relativistic pico second electron pulse

    SciTech Connect

    Jones, C.R.; Kosai, H.; Dutt, J.M.

    1995-12-31

    When an electron beams passes through boundaries of two different media with different dielectric constants, it generates radiation. The radiation emitted by the prebunched electron beam becomes coherent if the size of the bunch is smaller than the wavelength. Therefore, transition radiation can be considered as a possible broad band radiation source as well as a probe to the pico second and sub picosecond electron beam profiles. Using 1.2 MeV, 200 mA, macropulse electron beam, transition radiation was generated. The electron gun consists of 2.856 GHz Klystron, thermionic cathode. The emitted electron beam was bunched by passing through an alpha magnet. As a result of the combination, a pico second pulse (1.2 MeV, up to 80 A micropulse) was obtained. Experimental results, comparisons with the theory, and simulated electron beam profiles will be presented.

  7. VizieR Online Data Catalog: Helium-like ions with Z=10-36 transition rates (Si+, 2016)

    NASA Astrophysics Data System (ADS)

    Si, R.; Guo, X. L.; Wang, K.; Li, S.; Yan, J.; Chen, C. Y.; Brage, T.; Zou, Y. M.

    2016-08-01

    We provide accurate energies for the lowest singly excited 70 levels among 1snl(n<=6,l<=(n-1)) configurations and the lowest doubly excited 250 levels arising from the K-vacancy 2ln'l(n'<=6,l<=(n'-1)) configurations of helium-like ions with Z=10-36. Wavelengths, transition rates, oscillator strengths, and line strengths are calculated for the E1, M1, E2, and M2 transitions among these levels. The radiative lifetimes are reported for all the calculated levels. (4 data files).

  8. Transition Radiation as a Secondary Standard Source in the VUV.

    PubMed

    Böhm, W; Labs, D

    1971-09-01

    The optical radiation caused by electron bombardment of metallic surfaces was tested for its use as a secondary standard source in the VUV. Aluminum of high purity was found to be a suitable target material. The reproducibility of the radiation is of the order of 4% to 2% for 0.11 < lambda < 0.15 microm and 0.15 < lambda < 0.27 microm, respectively. In the spectral region 0.17 microm to 0.27 microm, the source was calibrated absolutely by comparison with a deuterium lamp of known absolute intensity.

  9. Pulse transit time and heart rate variability in sleep staging.

    PubMed

    Shahrbabaki, Sobhan Salari; Ahmed, Beena; Penzel, Thomas; Cvetkovic, Dean

    2016-08-01

    This paper presents a new and robust algorithm for detection of sleep stages by using the lead I of the Electrocardiography (ECG) and a fingertip Photoplethysmography (PPG) sensor, validated using multiple overnight PSG recordings consisting of 20 human subjects (9 insomniac and 11 healthy). Heart Rate Variability (HRV) and Pulse Transit Time (PTT) biomarkers which were extracted from ECG and PPG biosignals then employed to extract features. Distance Weighted k-Nearest Neighbours (DWk-NN) was used as classifier to differentiate sleep epochs. The validation of the algorithm was evaluated by Leave-One-Out-Cross-Validation method. The average accuracy of 73.4% with standard deviation of 6.4 was achieved while the algorithm could distinguish stages 2, 3 of non-rapid eye movement sleep by average sensitivity of almost 80%. The lowest mean sensitivity of 53% was for stage 1. These results demonstrate that an algorithm based on PTT and HRV spectral analysis is able to classify and distinguish sleep stages with high accuracy and sensitivity. In addition the proposed algorithm is capable to be improved and implemented as a wearable, comfortable and cheap instrument for sleep screening.

  10. Theoretical study on K, L, and M X-ray transition energies and rates of neptunium and its ions

    NASA Astrophysics Data System (ADS)

    Ismail Abdalla, Saber; Dong, Chen-Zhong; Wang, Xiang-Li; Zhou, Wei-Dong; Wu, Zhong-Wen

    2014-02-01

    The transition energies and electric dipole (E1) transition rates of the K, L, and M lines in neutral Np have been theoretically determined from the MultiConfiguration Dirac—Fock (MCDF) method. In the calculations, the contributions from Breit interaction and quantum electrodynamics (QED) effects (vacuum polarization and self-energy), as well as nuclear finite mass and volume effects, are taken into account. The calculated transition energies and rates are found to be in good agreement with other experimental and theoretical results. The accuracy of the results is estimated and discussed. Furthermore, we calculated the transition energies of the same lines radiating from the decaying transitions of the K-, L-, and M-shell hole states of Np ions with the charge states Np1+ to Np6+ for the first time. We found that for a specific line, the corresponding transition energies relating to all the Np ions are almost the same; it means the outermost electrons have a very small influence on the inner-shell transition processes.

  11. Progress on Radiative Transition Probabilities in Neutral Cerium

    NASA Astrophysics Data System (ADS)

    Curry, J. J.

    2009-10-01

    Cerium is a rare-earth atom that is currently used in energy-efficient metal-halide lamps because of its rich visible emission spectrum. More than 20,000 lines have been observed and classified for neutral cerium in the wavelength range of 340 nm to 1 μm (Bill Martin, unpublished). We recently derived more than 500 absolute transition probabilities from existing experimental data (J. Phys. D: Appl. Phys. 2009). Lawler and Den Hartog at the University of Wisconsin have made measurements that are expected to produce a few thousand transition probabilities. These advances, however, leave the data situation far short of what is needed to simulate an accurate global emission spectrum in numerical models of metal-halide lamps containing cerium. One possibility for closing this gap is through atomic structure calculations. Although it may be difficult for calculations to match the accuracy of measurements for any given transition, the global spectral distribution produced with calculated transition probabilities may still be satisfactory. For such a large number of lines, calculations may be the only realistic way to produce a reasonably complete set of data. We will discuss our recent atomic structure calculations of neutral cerium with the Cowan code based on a parametric fit of calculated energy level values to experimental values.

  12. Radiative heating rates during the Airborne Arctic Stratospheric Experiment

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.; Schoeberl, Mark R.; Lait, Leslie R.; Newman, Paul A.; Proffitt, Michael H.

    1990-01-01

    A radiative transfer model and observed temperature and ozone profiles are used to compute three-dimensional fields of heating rates for the Northern Hemisphere during 1989 Airborne Arctic Stratospheric Experiment. For a clear atmosphere, an average cooling of 0.2 to 0.4 K/day is computed in the regions of the ER-2 aircraft during flight days. Tropospheric clouds will increase the cooling by 0.1 to 0.2 K/day. These cooling rates are in good agreement with the diabatic cooling estimated from N2O data, Net heating rather than cooling is computed in the area of the ozone 'minihole' which had its maximum on 1/31/89 and 2/1/89 in the vicinity of the mission. On 1/31/89 the 50 and 30 mb net heating rates are 0.1 to 0.2 K/day for clear skies, and 0.05 to 0.1 K/day for cloudy skies.

  13. Radiative heating rates during the Airborne Arctic Stratospheric Experiment

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.; Schoeberl, Mark R.; Lait, Leslie R.; Newman, Paul A.; Proffitt, Michael H.

    1990-01-01

    A radiative transfer model and observed temperature and ozone profiles are used to compute three-dimensional fields of heating rates for the Northern Hemisphere during 1989 Airborne Arctic Stratospheric Experiment. For a clear atmosphere, an average cooling of 0.2 to 0.4 K/day is computed in the regions of the ER-2 aircraft during flight days. Tropospheric clouds will increase the cooling by 0.1 to 0.2 K/day. These cooling rates are in good agreement with the diabatic cooling estimated from N2O data, Net heating rather than cooling is computed in the area of the ozone 'minihole' which had its maximum on 1/31/89 and 2/1/89 in the vicinity of the mission. On 1/31/89 the 50 and 30 mb net heating rates are 0.1 to 0.2 K/day for clear skies, and 0.05 to 0.1 K/day for cloudy skies.

  14. Effects of rate of reinforcement and rate of change on choice behaviour in transition.

    PubMed

    Mazur, J E

    1997-05-01

    In two experiments with pigeons, a single variable-interval schedule assigned reinforcers to two response keys on a percentage basis. The percentage of reinforcers assigned to each key was changed every few sessions, and subjects' choice responses were recorded before and after each change. In Experiment 1, the overall rate of reinforcement was varied across conditions. The pigeons' choice responses adapted more quickly to a change in the reinforcement percentages when the overall reinforcement rates were higher, but acquisition rates varied by only about a factor of 3, whereas reinforcement rates were varied by about a factor of 9. In Experiment 2, the reinforcement percentages changed about every 8 sessions in Phases 1 and 3, but every 1 or 2 sessions in Phase 2. Pigeons' choice responses adapted to a change in reinforcement percentages more quickly in Phase 2 than in Phases 1 and 3. The results from both experiments pose difficulties for several prominent models of transitional choice behaviour. The results suggest that each successive reinforcer has more impact on a subject's subsequent choice behaviour when the overall rate of reinforcement is lower and when the reinforcement contingencies have changed frequently in the recent past.

  15. Radiation dose-rate meter using an energy-sensitive counter

    DOEpatents

    Kopp, Manfred K.

    1988-01-01

    A radiation dose-rate meter is provided which uses an energy-sensitive detector and combines charge quantization and pulse-rate measurement to monitor radiation dose rates. The charge from each detected photon is quantized by level-sensitive comparators so that the resulting total output pulse rate is proportional to the dose-rate.

  16. Bunch Length Measurements at the JLab FEL Using Coherent Transition and Synchrotron Radiation

    SciTech Connect

    Pavel Evtushenko; James Coleman; Kevin Jordan; J. Michael Klopf; George Neil; Gwyn Williams

    2006-05-01

    The JLab FEL is routinely operated with sub-picosecond bunches. The short bunch length is important for high gain of the FEL. Coherent transition radiation has been used for the bunch length measurements for many years [1]. This diagnostic can be used only in the pulsed beam mode. It is our goal to run the FEL with CW beam and a 74.85 MHz micropulse repetition rate, which, with the 135 pC nominal bunch charge corresponds to the beam average current of 10 mA. Hence it is very desirable to have the possibility of making bunch length measurements when running CW beam with any micropulse frequency. We use a Fourier transform infrared (FTIR) interferometer, which is essentially a Michelson interferometer, to measure the spectrum of the coherent synchrotron radiation generated in the last dipole of the magnetic bunch compressor upstream of the FEL wiggler. This noninvasive diagnostic provides bunch length measurements for CW beam operation at any micropulse frequency. We also compare the measurements made with the help of the FTIR interferometer with data obtained using the Martin-Puplett interferometer [1]. Results of the two diagnostics agree within 15 %. Here we present a description of the experimental setup, data evaluation procedure and results of the beam measurements.

  17. Impact of the terrestrial-aquatic transition on disparity and rates of evolution in the carnivoran skull.

    PubMed

    Jones, Katrina E; Smaers, Jeroen B; Goswami, Anjali

    2015-02-04

    Which factors influence the distribution patterns of morphological diversity among clades? The adaptive radiation model predicts that a clade entering new ecological niche will experience high rates of evolution early in its history, followed by a gradual slowing. Here we measure disparity and rates of evolution in Carnivora, specifically focusing on the terrestrial-aquatic transition in Pinnipedia. We analyze fissiped (mostly terrestrial, arboreal, and semi-arboreal, but also including the semi-aquatic otter) and pinniped (secondarily aquatic) carnivorans as a case study of an extreme ecological transition. We used 3D geometric morphometrics to quantify cranial shape in 151 carnivoran specimens (64 fissiped, 87 pinniped) and five exceptionally-preserved fossil pinnipeds, including the stem-pinniped Enaliarctos emlongi. Range-based and variance-based disparity measures were compared between pinnipeds and fissipeds. To distinguish between evolutionary modes, a Brownian motion model was compared to selective regime shifts associated with the terrestrial-aquatic transition and at the base of Pinnipedia. Further, evolutionary patterns were estimated on individual branches using both Ornstein-Uhlenbeck and Independent Evolution models, to examine the origin of pinniped diversity. Pinnipeds exhibit greater cranial disparity than fissipeds, even though they are less taxonomically diverse and, as a clade nested within fissipeds, phylogenetically younger. Despite this, there is no increase in the rate of morphological evolution at the base of Pinnipedia, as would be predicted by an adaptive radiation model, and a Brownian motion model of evolution is supported. Instead basal pinnipeds populated new areas of morphospace via low to moderate rates of evolution in new directions, followed by later bursts within the crown-group, potentially associated with ecological diversification within the marine realm. The transition to an aquatic habitat in carnivorans resulted in a shift

  18. Exclusive Measurements of the b to s gamma Transition Rate and Photon Energy Spectrum

    SciTech Connect

    Lees, J.P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Stugu, B.; Brown, David Nathan; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; Koch, H.; Schroeder, T.; Asgeirsson, D.J.; Hearty, C.; Mattison, T.S.; McKenna, J.A.; Khan, A.; Blinov, V.E.; Buzykaev, A.R.; /more authors..

    2012-08-30

    We use 429 fb{sup -1} of e{sup +}e{sup -} collision data collected at the {Upsilon}(4S) resonance with the BABAR detector to measure the radiative transition rate of b {yields} s{gamma} with a sum of 38 exclusive final states. The inclusive branching fraction with a minimum photon energy of 1.9 GeV is found to be {Beta}({bar B} {yields} Xs{gamma}) = (3.29 {+-} 0.19 {+-} 0.48) x 10{sup -4} where the first uncertainty is statistical and the second is systematic. We also measure the first and second moments of the photon energy spectrum and extract the best fit values for the heavy-quark parameters, m{sub b} and {mu}{sub {pi}}{sup 2}, in the kinetic and shape function models.

  19. Exclusive measurements of b→sγ transition rate and photon energy spectrum

    NASA Astrophysics Data System (ADS)

    Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Stugu, B.; Brown, D. N.; Kerth, L. T.; Kolomensky, Yu. G.; Lynch, G.; Koch, H.; Schroeder, T.; Asgeirsson, D. J.; Hearty, C.; Mattison, T. S.; McKenna, J. A.; Khan, A.; Blinov, V. E.; Buzykaev, A. R.; Druzhinin, V. P.; Golubev, V. B.; Kravchenko, E. A.; Onuchin, A. P.; Serednyakov, S. I.; Skovpen, Yu. I.; Solodov, E. P.; Todyshev, K. Yu.; Yushkov, A. N.; Bondioli, M.; Kirkby, D.; Lankford, A. J.; Mandelkern, M.; Atmacan, H.; Gary, J. W.; Liu, F.; Long, O.; Vitug, G. M.; Campagnari, C.; Hong, T. M.; Kovalskyi, D.; Richman, J. D.; West, C. A.; Eisner, A. M.; Kroseberg, J.; Lockman, W. S.; Martinez, A. J.; Schumm, B. A.; Seiden, A.; Chao, D. S.; Cheng, C. H.; Doll, D. A.; Echenard, B.; Flood, K. T.; Hitlin, D. G.; Ongmongkolkul, P.; Porter, F. C.; Rakitin, A. Y.; Andreassen, R.; Huard, Z.; Meadows, B. T.; Sokoloff, M. D.; Sun, L.; Bloom, P. C.; Ford, W. T.; Gaz, A.; Nauenberg, U.; Smith, J. G.; Wagner, S. R.; Ayad, R.; Toki, W. H.; Spaan, B.; Schubert, K. R.; Schwierz, R.; Bernard, D.; Verderi, M.; Clark, P. J.; Playfer, S.; Bettoni, D.; Bozzi, C.; Calabrese, R.; Cibinetto, G.; Fioravanti, E.; Garzia, I.; Luppi, E.; Munerato, M.; Negrini, M.; Piemontese, L.; Santoro, V.; Baldini-Ferroli, R.; Calcaterra, A.; de Sangro, R.; Finocchiaro, G.; Patteri, P.; Peruzzi, I. M.; Piccolo, M.; Rama, M.; Zallo, A.; Contri, R.; Guido, E.; Lo Vetere, M.; Monge, M. R.; Passaggio, S.; Patrignani, C.; Robutti, E.; Bhuyan, B.; Prasad, V.; Lee, C. L.; Morii, M.; Edwards, A. J.; Adametz, A.; Uwer, U.; Lacker, H. M.; Lueck, T.; Dauncey, P. D.; Behera, P. K.; Mallik, U.; Chen, C.; Cochran, J.; Meyer, W. T.; Prell, S.; Rubin, A. E.; Gritsan, A. V.; Guo, Z. J.; Arnaud, N.; Davier, M.; Derkach, D.; Grosdidier, G.; Le Diberder, F.; Lutz, A. M.; Malaescu, B.; Roudeau, P.; Schune, M. H.; Stocchi, A.; Wormser, G.; Lange, D. J.; Wright, D. M.; Chavez, C. A.; Coleman, J. P.; Fry, J. R.; Gabathuler, E.; Hutchcroft, D. E.; Payne, D. J.; Touramanis, C.; Bevan, A. J.; Di Lodovico, F.; Sacco, R.; Sigamani, M.; Cowan, G.; Brown, D. N.; Davis, C. L.; Denig, A. G.; Fritsch, M.; Gradl, W.; Griessinger, K.; Hafner, A.; Prencipe, E.; Bailey, D.; Barlow, R. J.; Jackson, G.; Lafferty, G. D.; Behn, E.; Cenci, R.; Hamilton, B.; Jawahery, A.; Roberts, D. A.; Dallapiccola, C.; Cowan, R.; Dujmic, D.; Sciolla, G.; Cheaib, R.; Lindemann, D.; Patel, P. M.; Robertson, S. H.; Biassoni, P.; Neri, N.; Palombo, F.; Stracka, S.; Cremaldi, L.; Godang, R.; Kroeger, R.; Sonnek, P.; Summers, D. J.; Nguyen, X.; Simard, M.; Taras, P.; De Nardo, G.; Monorchio, D.; Onorato, G.; Sciacca, C.; Martinelli, M.; Raven, G.; Jessop, C. P.; LoSecco, J. M.; Wang, W. F.; Honscheid, K.; Kass, R.; Brau, J.; Frey, R.; Sinev, N. B.; Strom, D.; Torrence, E.; Feltresi, E.; Gagliardi, N.; Margoni, M.; Morandin, M.; Posocco, M.; Rotondo, M.; Simi, G.; Simonetto, F.; Stroili, R.; Akar, S.; Ben-Haim, E.; Bomben, M.; Bonneaud, G. R.; Briand, H.; Calderini, G.; Chauveau, J.; Hamon, O.; Leruste, Ph.; Marchiori, G.; Ocariz, J.; Sitt, S.; Biasini, M.; Manoni, E.; Pacetti, S.; Rossi, A.; Angelini, C.; Batignani, G.; Bettarini, S.; Carpinelli, M.; Casarosa, G.; Cervelli, A.; Forti, F.; Giorgi, M. A.; Lusiani, A.; Oberhof, B.; Paoloni, E.; Perez, A.; Rizzo, G.; Walsh, J. J.; Lopes Pegna, D.; Olsen, J.; Smith, A. J. S.; Telnov, A. V.; Anulli, F.; Faccini, R.; Ferrarotto, F.; Ferroni, F.; Gaspero, M.; Li Gioi, L.; Mazzoni, M. A.; Piredda, G.; Bünger, C.; Grünberg, O.; Hartmann, T.; Leddig, T.; Schröder, H.; Voss, C.; Waldi, R.; Adye, T.; Olaiya, E. O.; Wilson, F. F.; Emery, S.; Hamel de Monchenault, G.; Vasseur, G.; Yèche, Ch.; Aston, D.; Bard, D. J.; Bartoldus, R.; Cartaro, C.; Convery, M. R.; Dorfan, J.; Dubois-Felsmann, G. P.; Dunwoodie, W.; Ebert, M.; Field, R. C.; Franco Sevilla, M.; Fulsom, B. G.; Gabareen, A. M.; Graham, M. T.; Grenier, P.; Hast, C.; Innes, W. R.; Kelsey, M. H.; Kim, P.; Kocian, M. L.; Leith, D. W. G. S.; Lewis, P.; Lindquist, B.; Luitz, S.; Luth, V.; Lynch, H. L.; MacFarlane, D. B.; Muller, D. R.; Neal, H.; Nelson, S.; Perl, M.; Pulliam, T.; Ratcliff, B. N.; Roodman, A.; Salnikov, A. A.; Schindler, R. H.; Snyder, A.; Su, D.; Sullivan, M. K.; Va'vra, J.; Wagner, A. P.; Wisniewski, W. J.; Wittgen, M.; Wright, D. H.; Wulsin, H. W.; Young, C. C.; Ziegler, V.; Park, W.; Purohit, M. V.; White, R. M.; Wilson, J. R.; Randle-Conde, A.; Sekula, S. J.; Bellis, M.; Benitez, J. F.; Burchat, P. R.; Miyashita, T. S.; Alam, M. S.; Ernst, J. A.; Gorodeisky, R.; Guttman, N.; Peimer, D. R.; Soffer, A.; Lund, P.; Spanier, S. M.; Eckmann, R.; Ritchie, J. L.; Ruland, A. M.; Schwitters, R. F.; Wray, B. C.; Izen, J. M.; Lou, X. C.; Bianchi, F.; Gamba, D.; Lanceri, L.; Vitale, L.; Martinez-Vidal, F.; Oyanguren, A.; Ahmed, H.; Albert, J.; Banerjee, Sw.; Bernlochner, F. U.; Choi, H. H. F.; King, G. J.; Kowalewski, R.; Lewczuk, M. J.; Nugent, I. M.; Roney, J. M.; Sobie, R. J.; Tasneem, N.; Gershon, T. J.; Harrison, P. F.; Latham, T. E.; Puccio, E. M. T.; Band, H. R.; Dasu, S.; Pan, Y.; Prepost, R.; Wu, S. L.

    2012-09-01

    We use 429fb-1 of e+e- collision data collected at the Υ(4S) resonance with the BABAR detector to measure the radiative transition rate of b→sγ with a sum of 38 exclusive final states. The inclusive branching fraction with a minimum photon energy of 1.9 GeV is found to be B(B¯→Xsγ)=(3.29±0.19±0.48)×10-4 where the first uncertainty is statistical and the second is systematic. We also measure the first and second moments of the photon energy spectrum and extract the best-fit values for the heavy-quark parameters, mb and μπ2, in the kinetic and shape function models.

  20. Investigating rare events with nonequilibrium work measurements. II. Transition and reaction rates.

    PubMed

    Moradi, Mahmoud; Sagui, Celeste; Roland, Christopher

    2014-01-21

    We present a formalism for investigating transition pathways and transition probabilities for rare events in biomolecular systems. The formalism is based on combining Transition Path Theory with the results of nonequilibrium work relations, and shows that the equilibrium and nonequilibrium transition rates are in fact related. Aside from its fundamental importance, this allows for the calculation of relative equilibrium reaction rates with driven nonequilibrium simulations such as Steered Molecular Dynamics. The workings of the formalism are illustrated with a few typical numerical examples.

  1. A transition radiation detector for RHIC featuring accurate tracking and dE/dx particle identification

    SciTech Connect

    O`Brien, E.; Lissauer, D.; McCorkle, S.; Polychronakos, V.; Takai, H.; Chi, C.Y.; Nagamiya, S.; Sippach, W.; Toy, M.; Wang, D.; Wang, Y.F.; Wiggins, C.; Willis, W.; Cherniatin, V.; Dolgoshein, B.; Bennett, M.; Chikanian, A.; Kumar, S.; Mitchell, J.T.; Pope, K.

    1991-12-31

    We describe the results of a test ran involving a Transition Radiation Detector that can both distinguish electrons from pions which momenta greater titan 0.7 GeV/c and simultaneously track particles passing through the detector. The particle identification is accomplished through a combination of the detection of Transition Radiation from the electron and the differences in electron and pion energy loss (dE/dx) in the detector. The dE/dx particle separation is most, efficient below 2 GeV/c while particle ID utilizing Transition Radiation effective above 1.5 GeV/c. Combined, the electron-pion separation is-better than 5 {times} 10{sup 2}. The single-wire, track-position resolution for the TRD is {approximately}230 {mu}m.

  2. Measurement of Sub-Picosecond Electron Bunches via Electro-Optic Sampling of Coherent Transition Radiation

    SciTech Connect

    Maxwell, Timothy John

    2012-01-01

    Future collider applications as well as present high-gradient laser plasma wakefield accelerators and free-electron lasers operating with picosecond bunch durations place a higher demand on the time resolution of bunch distribution diagnostics. This demand has led to significant advancements in the field of electro-optic sampling over the past ten years. These methods allow the probing of diagnostic light such as coherent transition radiation or the bunch wakefields with sub-picosecond time resolution. We present results on the single-shot electro-optic spectral decoding of coherent transition radiation from bunches generated at the Fermilab A0 photoinjector laboratory. A longitudinal double-pulse modulation of the electron beam is also realized by transverse beam masking followed by a transverse-to-longitudinal phase-space exchange beamline. Live profile tuning is demonstrated by upstream beam focusing in conjunction with downstream monitoring of single-shot electro-optic spectral decoding of the coherent transition radiation.

  3. A Coherent X-Ray Source Using Transition Radiation

    DTIC Science & Technology

    1992-02-29

    that of wigglers . GOAL II. Reduce the bandwidth of the x-ray source by either photoabsorption edge trunca- tion or by using the resonance effect. Use...current for the RTR source in the comparison with synchrotron radiators, then the brightness of the RTR source becomes close to that of wigglers . In Fig...5.2, we compare the brightness of the two coherent stacks discussed above along with the brightness of SSRL bending magnet and wiggler . The peak

  4. Radiation shielding in transit to Mars and on the surface

    NASA Technical Reports Server (NTRS)

    Conway, Edmund J.; Townsend, Lawrence W.

    1992-01-01

    An evaluation is presented of the current understanding of the space radiation environment and the primary considerations of spacecrew exposure effects and limits. By using a two-solar particle event scenario for a 'sprint' mission to Mars, estimates are developed for the requisite shielding of the transfer vehicle and Martian surface habitat. Many uncertainties, however, are noted to have gone into these mission dose estimates; the combination of these uncertainties into an error-bar on shield mass lies beyond current capabilities.

  5. Radiative corrections to 0/sup +/-0/sup +/. beta. transitions

    SciTech Connect

    Jaus, W.; Rasche, G.

    1987-06-01

    We reexamine and refine our former analysis of electromagnetic corrections to 0/sup +/-0/sup +/ ..beta.. transitions. The disagreement with a recent approximate calculation of Sirlin and Zucchini is due to an error in our earlier numerical computation. The new results lead to much better agreement between the Ft values of the eight accurately studied decays. We find an average value of Ft = 3072.4 +- 1.6 s. .AE

  6. Radiative corrections to 0+-0+ β transitions

    NASA Astrophysics Data System (ADS)

    Jaus, W.; Rasche, G.

    1987-06-01

    We reexamine and refine our former analysis of electromagnetic corrections to 0+-0+ β transitions. The disagreement with a recent approximate calculation of Sirlin and Zucchini is due to an error in our earlier numerical computation. The new results lead to much better agreement between the Ft values of the eight accurately studied decays. We find an average value of Ft =3072.4+/-1.6 s. .AE

  7. Calculation of collisional and radiative transition probabilities between excited argon levels

    NASA Astrophysics Data System (ADS)

    Kimura, A.; Kobayashi, H.; Nishida, M.; Valentin, P.

    1985-08-01

    Average radiative transition probabilities for argon atoms have been calculated for transitions between 24 levels in two groups characterized by the atomic core terms 2P(1/2) and 2P(3/2) by using the method of Bates and Damgaard. The results are compared with data in the NBS tables (Wiese et al.) and with those of Katsonis and Drawin. Satisfactory agreement is found for the order of magnitude, even for transitions between lower lying levels. Parameters, which appear in Drawin's semiempirical cross-section expressions for electronic excitation of optically allowed and parity-forbidden transitions, are determined with the multipole expansion method proposed by Sobel'man for transitions between the specified levels. Most of these are easily obtained, but the method must be improved for transitions between levels having the same azimuthal quantum number because the summation over the constituent terms does not converge.

  8. Transition to turbulence and noise radiation in heated coaxial jet flows

    SciTech Connect

    Gloor, Michael Bühler, Stefan; Kleiser, Leonhard

    2016-04-15

    Laminar-turbulent transition and noise radiation of a parametrized set of subsonic coaxial jet flows with a hot primary (core) stream are investigated numerically by Large-Eddy Simulation (LES) and direct noise computation. This study extends our previous research on local linear stability of heated coaxial jet flows by analyzing the nonlinear evolution of initially laminar flows disturbed by a superposition of small-amplitude unstable eigenmodes. First, a baseline configuration is studied to shed light on the flow dynamics of coaxial jet flows. Subsequently, LESs are performed for a range of Mach and Reynolds numbers to systematically analyze the influences of the temperature and the velocity ratios between the primary and the secondary (bypass) stream. The results provide a basis for a detailed analysis of fundamental flow-acoustic phenomena in the considered heated coaxial jet flows. Increasing the primary-jet temperature leads to an increase of fluctuation levels and to an amplification of far-field noise, especially at low frequencies. Strong mixing between the cold bypass stream and the hot primary stream as well as the intermittent character of the flow field at the end of the potential core lead to a pronounced noise radiation at an aft angle of approximately 35{sup ∘}. The velocity ratio strongly affects the shear-layer development and therefore also the noise generation mechanisms. Increasing the secondary-stream velocity amplifies the dominance of outer shear-layer perturbations while the disturbance growth rates in the inner shear layer decrease. Already for r{sub mic} > 40R{sub 1}, where r{sub mic} is the distance from the end of the potential core and R{sub 1} is the core-jet radius, a perfect 1/r{sub mic} decay of the sound pressure amplitudes is observed. The potential-core length increases for higher secondary-stream velocities which leads to a shift of the center of the dominant acoustic radiation in the downstream direction.

  9. Transition to turbulence and noise radiation in heated coaxial jet flows

    NASA Astrophysics Data System (ADS)

    Gloor, Michael; Bühler, Stefan; Kleiser, Leonhard

    2016-04-01

    Laminar-turbulent transition and noise radiation of a parametrized set of subsonic coaxial jet flows with a hot primary (core) stream are investigated numerically by Large-Eddy Simulation (LES) and direct noise computation. This study extends our previous research on local linear stability of heated coaxial jet flows by analyzing the nonlinear evolution of initially laminar flows disturbed by a superposition of small-amplitude unstable eigenmodes. First, a baseline configuration is studied to shed light on the flow dynamics of coaxial jet flows. Subsequently, LESs are performed for a range of Mach and Reynolds numbers to systematically analyze the influences of the temperature and the velocity ratios between the primary and the secondary (bypass) stream. The results provide a basis for a detailed analysis of fundamental flow-acoustic phenomena in the considered heated coaxial jet flows. Increasing the primary-jet temperature leads to an increase of fluctuation levels and to an amplification of far-field noise, especially at low frequencies. Strong mixing between the cold bypass stream and the hot primary stream as well as the intermittent character of the flow field at the end of the potential core lead to a pronounced noise radiation at an aft angle of approximately 35∘. The velocity ratio strongly affects the shear-layer development and therefore also the noise generation mechanisms. Increasing the secondary-stream velocity amplifies the dominance of outer shear-layer perturbations while the disturbance growth rates in the inner shear layer decrease. Already for rmic > 40R1, where rmic is the distance from the end of the potential core and R1 is the core-jet radius, a perfect 1/rmic decay of the sound pressure amplitudes is observed. The potential-core length increases for higher secondary-stream velocities which leads to a shift of the center of the dominant acoustic radiation in the downstream direction.

  10. The phase transition in VO2 probed using x-ray, visible and infrared radiations

    DOE PAGES

    Kumar, Suhas; Strachan, John Paul; Kilcoyne, A. L. David; ...

    2016-02-15

    Vanadium dioxide (VO2) is a model system that has been used to understand closely occurring multiband electronic (Mott) and structural (Peierls) transitions for over half a century due to continued scientific and technological interests. Among the many techniques used to study VO2, the most frequently used involve electromagnetic radiation as a probe. Understanding of the distinct physical information provided by different probing radiations is incomplete, mostly owing to the complicated nature of the phase transitions. Here, we use transmission of spatially averaged infrared (λ = 1.5 μm) and visible (λ = 500 nm) radiations followed by spectroscopy and nanoscale imagingmore » using x-rays (λ = 2.25–2.38 nm) to probe the same VO2 sample while controlling the ambient temperature across its hysteretic phase transitions and monitoring its electrical resistance. We directly observed nanoscale puddles of distinct electronic and structural compositions during the transition. The two main results are that, during both heating and cooling, the transition of infrared and visible transmission occurs at significantly lower temperatures than the Mott transition, and the electronic (Mott) transition occurs before the structural (Peierls) transition in temperature. We use our data to provide insights into possible microphysical origins of the different transition characteristics. We highlight that it is important to understand these effects because small changes in the nature of the probe can yield quantitatively, and even qualitatively, different results when applied to a non-trivial multiband phase transition. Our results guide more judicious use of probe type and interpretation of the resulting data.« less

  11. The phase transition in VO2 probed using x-ray, visible and infrared radiations

    NASA Astrophysics Data System (ADS)

    Kumar, Suhas; Strachan, John Paul; Kilcoyne, A. L. David; Tyliszczak, Tolek; Pickett, Matthew D.; Santori, Charles; Gibson, Gary; Williams, R. Stanley

    2016-02-01

    Vanadium dioxide (VO2) is a model system that has been used to understand closely occurring multiband electronic (Mott) and structural (Peierls) transitions for over half a century due to continued scientific and technological interests. Among the many techniques used to study VO2, the most frequently used involve electromagnetic radiation as a probe. Understanding of the distinct physical information provided by different probing radiations is incomplete, mostly owing to the complicated nature of the phase transitions. Here, we use transmission of spatially averaged infrared (λ = 1.5 μm) and visible (λ = 500 nm) radiations followed by spectroscopy and nanoscale imaging using x-rays (λ = 2.25-2.38 nm) to probe the same VO2 sample while controlling the ambient temperature across its hysteretic phase transitions and monitoring its electrical resistance. We directly observed nanoscale puddles of distinct electronic and structural compositions during the transition. The two main results are that, during both heating and cooling, the transition of infrared and visible transmission occurs at significantly lower temperatures than the Mott transition, and the electronic (Mott) transition occurs before the structural (Peierls) transition in temperature. We use our data to provide insights into possible microphysical origins of the different transition characteristics. We highlight that it is important to understand these effects because small changes in the nature of the probe can yield quantitatively, and even qualitatively, different results when applied to a non-trivial multiband phase transition. Our results guide more judicious use of probe type and interpretation of the resulting data.

  12. Monte Carlo simulations of the transition radiation detector of the AMS-02 experiment

    NASA Astrophysics Data System (ADS)

    Räihä, T.; Bachlechner, A.; Beischer, B.; Chung, C. H.; Gast, H.; Schael, S.; Siedenburg, T.

    2017-10-01

    The Transition Radiation Detector of the AMS-02 experiment on the International Space Station is used for the separation of cosmic-ray positrons and electrons from protons and anti-protons, and for the identification of nuclei up to carbon (Z ≤ 6). We present the Geant4 simulation that is used to describe the ionization and transition radiation processes and compare its results to flight data from AMS-02. After applying empirical corrections to the simulated data, the particle energy deposition and likelihood distributions in the TRD are described with high accuracy.

  13. Ultrafast imaging of terahertz Cherenkov waves and transition-like radiation in LiNbO₃.

    PubMed

    Wang, Zhenyou; Su, FuHai; Hegmann, Frank A

    2015-03-23

    We use ultrafast phase-contrast imaging to directly observethe cone-like terahertz (THz) Cherenkov wave generated by optical rectification of femtosecond laser pulses focused into bulk lithium niobate (LiNbO₃) single crystals. The transverse imaging geometry allows the Cherenkov angle, THz wave velocity, and optical pump pulse group velocity to be measured. Furthermore, transition-like THz radiation generated by the femtosecond laser pulse at the air-crystal boundary is observed. The effect of optical pump pulse polarization on the generation of THz Cherenkov waves and transition-like radiation in LiNbO₃ is also investigated.

  14. 10 CFR 35.70 - Surveys of ambient radiation exposure rate.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Surveys of ambient radiation exposure rate. 35.70 Section... Requirements § 35.70 Surveys of ambient radiation exposure rate. (a) In addition to the surveys required by Part 20 of this chapter, a licensee shall survey with a radiation detection survey instrument at the...

  15. 10 CFR 35.70 - Surveys of ambient radiation exposure rate.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Surveys of ambient radiation exposure rate. 35.70 Section... Requirements § 35.70 Surveys of ambient radiation exposure rate. (a) In addition to the surveys required by Part 20 of this chapter, a licensee shall survey with a radiation detection survey instrument at the...

  16. 10 CFR 35.70 - Surveys of ambient radiation exposure rate.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Surveys of ambient radiation exposure rate. 35.70 Section... Requirements § 35.70 Surveys of ambient radiation exposure rate. (a) In addition to the surveys required by Part 20 of this chapter, a licensee shall survey with a radiation detection survey instrument at the...

  17. 10 CFR 35.70 - Surveys of ambient radiation exposure rate.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Surveys of ambient radiation exposure rate. 35.70 Section... Requirements § 35.70 Surveys of ambient radiation exposure rate. (a) In addition to the surveys required by Part 20 of this chapter, a licensee shall survey with a radiation detection survey instrument at the...

  18. 10 CFR 35.70 - Surveys of ambient radiation exposure rate.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Surveys of ambient radiation exposure rate. 35.70 Section... Requirements § 35.70 Surveys of ambient radiation exposure rate. (a) In addition to the surveys required by Part 20 of this chapter, a licensee shall survey with a radiation detection survey instrument at the...

  19. Formation region effects in transition radiation, bremsstrahlung, and ionization loss of ultrarelativistic electrons

    NASA Astrophysics Data System (ADS)

    Trofymenko, S. V.; Shul'ga, N. F.

    2016-11-01

    The processes of transition radiation and bremsstrahlung by an ultrarelativistic electron as well as the effect of transition radiation influence upon the electron ionization loss in thin layer of substance are theoretically investigated in the case when radiation formation region has macroscopically large size. Special attention is drawn to transition radiation (TR) generated during the traversal of thin metallic plate by the electron previously deflected from its initial direction of motion. In this case TR characteristics are calculated for realistic (circular) shape of the electron deflection trajectory. The difference of such characteristics under certain conditions from the ones obtained previously with the use of approximation of anglelike shape of the electron trajectory (instant deflection) is shown. The problem of measurement of bremsstrahlung characteristics in the prewave zone is investigated. The expressions defining the measured radiation distribution for arbitrary values of the size and the position of the detector used for radiation registration are derived. The problem of TR influence upon the electron ionization loss in thin plate and in a system of two plates is discussed. The proposal for experimental investigation of such effect is formulated.

  20. Circuits and methods for determination and control of signal transition rates in electrochemical cells

    DOEpatents

    Jamison, David Kay

    2016-04-12

    A charge/discharge input is for respectively supplying charge to, or drawing charge from, an electrochemical cell. A transition modifying circuit is coupled between the charge/discharge input and a terminal of the electrochemical cell and includes at least one of an inductive constituent, a capacitive constituent and a resistive constituent selected to generate an adjusted transition rate on the terminal sufficient to reduce degradation of a charge capacity characteristic of the electrochemical cell. A method determines characteristics of the transition modifying circuit. A degradation characteristic of the electrochemical cell is analyzed relative to a transition rate of the charge/discharge input applied to the electrochemical cell. An adjusted transition rate is determined for a signal to be applied to the electrochemical cell that will reduce the degradation characteristic. At least one of an inductance, a capacitance, and a resistance is selected for the transition modifying circuit to achieve the adjusted transition rate.

  1. Report on the Radiation Effects Testing of the Infrared and Optical Transition Radiation Camera Systems

    SciTech Connect

    Holloway, Michael Andrew

    2016-04-20

    Presented in this report are the results tests performed at Argonne National Lab in collaboration with Los Alamos National Lab to assess the reliability of the critical 99Mo production facility beam monitoring diagnostics. The main components of the beam monitoring systems are two cameras that will be exposed to radiation during accelerator operation. The purpose of this test is to assess the reliability of the cameras and related optical components when exposed to operational radiation levels. Both X-ray and neutron radiation could potentially damage camera electronics as well as the optical components such as lenses and windows. This report covers results of the testing of component reliability when exposed to X-ray radiation. With the information from this study we provide recommendations for implementing protective measures for the camera systems in order to minimize the occurrence of radiation-induced failure within a ten month production run cycle.

  2. pNRQCD determination of E1 radiative transitions

    NASA Astrophysics Data System (ADS)

    Steinbeißer, Sebastian; Segovia, Jorge

    2017-03-01

    This contribution contains the first numerical computation of the complete set of relativistic corrections of relative order v2 for electric dipole (E1) transitions in heavy quarkonium; in particular, for the processes χbj(1P) → ϒ(1S) + γ with J = 0, 1, 2. We assume that the momentum transfer of the heavy mesons involved in the reactions lies in the weak-coupling regime of the low-energy effective field theory potential non-relativistic QCD (pNRQCD) and thus a full perturbative calculation can be performed.

  3. Radiative and nonradiative spontaneous decay rates for an electric quadrupole source in the vicinity of a spherical particle

    SciTech Connect

    Guzatov, D. V.

    2016-04-15

    Analytic expressions for the radiative and nonradiative decay rates for an electric quadrupole source (atom, molecule) in the vicinity of a spherical particle (dielectric, metal) have been derived and analyzed within the classical electrodynamics. It has been shown that the highest increase in the decay rates appears in the quasi-static case, when the wavelength of the transition in question is much larger than the characteristic size of the system formed by the particle and the quadrupole. Asymptotic expressions for the decay rates have been derived for this case.

  4. 49 CFR 1302.43 - Applicable rates on shipments in transit when statute becomes effective.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 9 2011-10-01 2011-10-01 false Applicable rates on shipments in transit when... shipments in transit when statute becomes effective. The following conditions are hereby prescribed as... during the time when export or import shipments are in transit to or from the ports of export or...

  5. 49 CFR 1302.43 - Applicable rates on shipments in transit when statute becomes effective.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Applicable rates on shipments in transit when... shipments in transit when statute becomes effective. The following conditions are hereby prescribed as... during the time when export or import shipments are in transit to or from the ports of export or...

  6. 49 CFR 1302.43 - Applicable rates on shipments in transit when statute becomes effective.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 9 2012-10-01 2012-10-01 false Applicable rates on shipments in transit when... shipments in transit when statute becomes effective. The following conditions are hereby prescribed as... during the time when export or import shipments are in transit to or from the ports of export or...

  7. 49 CFR 1302.43 - Applicable rates on shipments in transit when statute becomes effective.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 9 2014-10-01 2014-10-01 false Applicable rates on shipments in transit when... shipments in transit when statute becomes effective. The following conditions are hereby prescribed as... during the time when export or import shipments are in transit to or from the ports of export or...

  8. 49 CFR 1302.43 - Applicable rates on shipments in transit when statute becomes effective.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 9 2013-10-01 2013-10-01 false Applicable rates on shipments in transit when... shipments in transit when statute becomes effective. The following conditions are hereby prescribed as... during the time when export or import shipments are in transit to or from the ports of export or...

  9. Transitions between Andean and Amazonian centers of endemism in the radiation of some arboreal rodents.

    PubMed

    Upham, Nathan S; Ojala-Barbour, Reed; Brito M, Jorge; Velazco, Paúl M; Patterson, Bruce D

    2013-09-09

    The tropical Andes and Amazon are among the richest regions of endemism for mammals, and each has given rise to extensive in situ radiations. Various animal lineages have radiated ex situ after colonizing one of these regions from the other: Amazonian clades of dendrobatid frogs and passerine birds may have Andean ancestry, and transitions from the Amazon to Andes may be even more common. To examine biogeographic transitions between these regions, we investigated the evolutionary history of three clades of rodents in the family Echimyidae: bamboo rats (Dactylomys-Olallamys-Kannabateomys), spiny tree-rats (Mesomys-Lonchothrix), and brush-tailed rats (Isothrix). Each clade is distributed in both the Andes and Amazonia, and is more diverse in the lowlands. We used two mitochondrial (cyt-b and 12S) and three nuclear (GHR, vWF, and RAG1) markers to reconstruct their phylogenetic relationships. Tree topologies and ancestral geographic ranges were then used to determine whether Andean forms were basal to or derived from lowland radiations. Four biogeographic transitions are identified among the generic radiations. The bamboo rat clade unambiguously originated in the Amazon ca. 9 Ma, followed by either one early transition to the Andes (Olallamys) and a later move to the Amazon (Dactylomys), or two later shifts to the Andes (one in each genus). The Andean species of both Dactylomys and Isothrix are sister to their lowland species, raising the possibility that highland forms colonized the Amazon Basin. However, uncertainty in their reconstructed ancestral ranges obscures the origin of these transitions. The lone Andean species of Mesomys is confidently nested within the lowland radiation, thereby indicating an Amazon-to-Andes transition ca. 2 Ma. Differences in the timing of these biogeographic transitions do not appear to explain the different polarities of these trees. Instead, even within the radiation of a single family, both Andean and Amazonian centers of endemism

  10. Transitions between Andean and Amazonian centers of endemism in the radiation of some arboreal rodents

    PubMed Central

    2013-01-01

    Background The tropical Andes and Amazon are among the richest regions of endemism for mammals, and each has given rise to extensive in situ radiations. Various animal lineages have radiated ex situ after colonizing one of these regions from the other: Amazonian clades of dendrobatid frogs and passerine birds may have Andean ancestry, and transitions from the Amazon to Andes may be even more common. To examine biogeographic transitions between these regions, we investigated the evolutionary history of three clades of rodents in the family Echimyidae: bamboo rats (Dactylomys-Olallamys-Kannabateomys), spiny tree-rats (Mesomys-Lonchothrix), and brush-tailed rats (Isothrix). Each clade is distributed in both the Andes and Amazonia, and is more diverse in the lowlands. We used two mitochondrial (cyt-b and 12S) and three nuclear (GHR, vWF, and RAG1) markers to reconstruct their phylogenetic relationships. Tree topologies and ancestral geographic ranges were then used to determine whether Andean forms were basal to or derived from lowland radiations. Results Four biogeographic transitions are identified among the generic radiations. The bamboo rat clade unambiguously originated in the Amazon ca. 9 Ma, followed by either one early transition to the Andes (Olallamys) and a later move to the Amazon (Dactylomys), or two later shifts to the Andes (one in each genus). The Andean species of both Dactylomys and Isothrix are sister to their lowland species, raising the possibility that highland forms colonized the Amazon Basin. However, uncertainty in their reconstructed ancestral ranges obscures the origin of these transitions. The lone Andean species of Mesomys is confidently nested within the lowland radiation, thereby indicating an Amazon-to-Andes transition ca. 2 Ma. Conclusions Differences in the timing of these biogeographic transitions do not appear to explain the different polarities of these trees. Instead, even within the radiation of a single family, both Andean and

  11. A Design Report for the Optical Transition Radiation Imager for the LCLS Undulator

    SciTech Connect

    Yang, Bingxin

    2010-12-13

    The Linac Coherent Light Source (LCLS), a free-electron x-ray laser, is under design and construction. Its high-intensity electron beam, 3400 A in peak current and 46 TW in peak power, is concentrated in a small area (37 micrometer in rms radius) inside its undulator. Ten optical transition radiation (OTR) imagers are planned between the undulator segments for characterizing the transverse profiles of the electron beam. In this note, we report on the optical and mechanical design of the OTR imager. Through a unique optical arrangement, using a near-normal-incidence screen and a multi-layer coated mirror, this imager will achieve a fine resolution (12 micrometer or better) over the entire field of view (8 mm x 5 mm), with a high efficiency for single-shot imaging. A digital camera will be used to read out the beam images in a programmable region (5 mm x 0.5 mm) at the full beam repetition rate (120 Hz), or over the entire field at a lower rate (10 Hz). Its built-in programmable amplifier will be used as an electronic intensity control.

  12. Radiation Hardened, Modulator ASIC for High Data Rate Communications

    NASA Technical Reports Server (NTRS)

    McCallister, Ron; Putnam, Robert; Andro, Monty; Fujikawa, Gene

    2000-01-01

    Satellite-based telecommunication services are challenged by the need to generate down-link power levels adequate to support high quality (BER approx. equals 10(exp 12)) links required for modem broadband data services. Bandwidth-efficient Nyquist signaling, using low values of excess bandwidth (alpha), can exhibit large peak-to-average-power ratio (PAPR) values. High PAPR values necessitate high-power amplifier (HPA) backoff greater than the PAPR, resulting in unacceptably low HPA efficiency. Given the high cost of on-board prime power, this inefficiency represents both an economical burden, and a constraint on the rates and quality of data services supportable from satellite platforms. Constant-envelope signals offer improved power-efficiency, but only by imposing a severe bandwidth-efficiency penalty. This paper describes a radiation- hardened modulator which can improve satellite-based broadband data services by combining the bandwidth-efficiency of low-alpha Nyquist signals with high power-efficiency (negligible HPA backoff).

  13. Technological Advancements and Error Rates in Radiation Therapy Delivery

    SciTech Connect

    Margalit, Danielle N.

    2011-11-15

    Purpose: Technological advances in radiation therapy (RT) delivery have the potential to reduce errors via increased automation and built-in quality assurance (QA) safeguards, yet may also introduce new types of errors. Intensity-modulated RT (IMRT) is an increasingly used technology that is more technically complex than three-dimensional (3D)-conformal RT and conventional RT. We determined the rate of reported errors in RT delivery among IMRT and 3D/conventional RT treatments and characterized the errors associated with the respective techniques to improve existing QA processes. Methods and Materials: All errors in external beam RT delivery were prospectively recorded via a nonpunitive error-reporting system at Brigham and Women's Hospital/Dana Farber Cancer Institute. Errors are defined as any unplanned deviation from the intended RT treatment and are reviewed during monthly departmental quality improvement meetings. We analyzed all reported errors since the routine use of IMRT in our department, from January 2004 to July 2009. Fisher's exact test was used to determine the association between treatment technique (IMRT vs. 3D/conventional) and specific error types. Effect estimates were computed using logistic regression. Results: There were 155 errors in RT delivery among 241,546 fractions (0.06%), and none were clinically significant. IMRT was commonly associated with errors in machine parameters (nine of 19 errors) and data entry and interpretation (six of 19 errors). IMRT was associated with a lower rate of reported errors compared with 3D/conventional RT (0.03% vs. 0.07%, p = 0.001) and specifically fewer accessory errors (odds ratio, 0.11; 95% confidence interval, 0.01-0.78) and setup errors (odds ratio, 0.24; 95% confidence interval, 0.08-0.79). Conclusions: The rate of errors in RT delivery is low. The types of errors differ significantly between IMRT and 3D/conventional RT, suggesting that QA processes must be uniquely adapted for each technique. There

  14. The Broadening of Spectral Lines by Autoionization, Radiative Transitions, and Collisions.

    DTIC Science & Technology

    1980-10-22

    nnounced Justif icai ¢:c Distr -- / Av~a..’ ’ "Co~es fl/-i iii st THE BRAODENING OF SPECTRAL LINES BY AUTOIONIZATION, RADIATIVE TRANSITIONS, AND...of NY Physics Department Stony Brook, New York 11794 Meerut College Meerut, 250001 India Meyerhof, W.E. Department of Physics Stanford University

  15. Oscillatory quantum screening effects on the transition bremsstrahlung radiation in quantum plasmas

    NASA Astrophysics Data System (ADS)

    Jung, Young-Dae

    2011-06-01

    The oscillatory screening effects on the transition bremsstrahlung radiation due to the polarization interaction between the electron and shielding cloud are investigated in dense quantum plasmas. The impact-parameter analysis with the modified Debye-Hückel potential is applied to obtain the bremsstrahlung radiation cross section as a function of the quantum wave number, impact parameter, photon energy, and projectile energy. The results show that the oscillatory quantum screening effect strongly suppresses the transition bremsstrahlung radiation spectrum in dense quantum plasmas. It is also found that the oscillatory quantum screening effect is more significant near the maximum peak of the bremsstrahlung radiation cross section. In addition, the maximum peak of the bremsstrahlung radiation cross section is getting close to the center of the shielding cloud as increasing quantum wave number. It is interesting to note that the range of the bremsstrahlung photon energy would be broadened with an increase of the oscillatory screening effect. It is also found that the oscillatory screening effects on the transition bremsstrahlung spectrum decreases with increasing projectile energy.

  16. Diffraction effects in coherent transition radiation diagnostics for sub-mm bunch length measurement

    SciTech Connect

    Maxwell, T.J.; Mihalcea, D.; Piot, P.; /Northern Illinois U. /Fermilab

    2008-09-01

    Electrons crossing the boundary between different media generate bursts of transition radiation. In the case of bunches of N electrons, the radiation is coherent and has an N-squared enhancement at wavelengths related to the longitudinal bunch distribution. This coherent transition radiation has therefore attracted attention as an interceptive charged particle beam diagnostic technique. Many analytical descriptions have been devised describing the spectral distribution generated by electron bunches colliding with thin metallic foils making different simplifying assumptions. For typical bunches having lengths in the sub-millimeter range, measurable spectra are generated up into the millimeter range. Analysis of this THz radiation is performed using optical equipment tens of millimeters in size. This gives rise to concern that optical diffraction effects may spread the wavefront of interest into regions larger than the optical elements and partially escape detection, generating a wavelength-dependent instrument response. In this paper we present a model implementing vector diffraction theory to analyze these effects in bunch length diagnostics based on coherent transition radiation.

  17. Longitudinal electron bunch diagnostics using coherent transition radiation at the IRFEL

    NASA Astrophysics Data System (ADS)

    Zhou, T. Y.; Yang, Y. L.; Sun, B. G.; Tang, L. L.; Lu, P.; Zhou, Z. R.; Wu, F. F.; Liu, X. Y.

    2016-09-01

    A longitudinal electron bunch diagnostics system is developing to measure the longitudinal bunch charge distribution for the new IRFEL at National Synchrotron Radiation Laboratory (NSRL). We use a Martin-Puplett interferometer, which is essentially a Michelson interferometer, to measure the spectrum of the coherent transition radiation produced by electrons through a thin metallic foil. Frequency components of coherent transition radiation have a relationship with the bunch form factor, which is described by the square modulus of the Fourier transform of the bunch distribution. Then several techniques, including a Kramers-Kronig analysis, have been applied to determine the longitudinal bunch charge distribution. The details of the design and theoretical investigation will be described in this paper.

  18. Observation of optical transition radiation from electron beams generated by laser plasma accelerator

    NASA Astrophysics Data System (ADS)

    Lin, Chen; Nakamura, K.; Van, Tilborg J.; Gonsalves, A. J.; Sokollik, T.; Shiraishi, S.; Leemans, W. P.; Guo, Zhi-Yu

    2013-02-01

    Laser plasma accelerators (LPAs) have made great progress, achieving electron beam with energy up to 1 GeV from a centimeter scale capillary plasma waveguide. Here, we report the measurement of optical transition radiation (OTR) from the capillary-based LPA electron beams. Transition radiation images, produced by electrons passing through two separate foils (located at 2.3 m and 3.8 m away from the exit of the LPA) were recorded with a high resolution imaging system, respectively. Two magnetic quadrupole lenses were placed right after the capillary to focus and collimate the electron beams. Significant localized spikes appeared in the OTR images when the electron beam was focused by the magnetic quadrupole lenses, indicating the coherence of the radiation and the existence of ultrashort longitudinal structures inside the electron beam.

  19. Simulation of the transition radiation detection conditions in the ATLAS TRT detector filled with argon and krypton gas mixtures

    SciTech Connect

    Boldyrev, A. S.; Maevskiy, A. S.

    2015-12-15

    Performance of the Transition Radiation Tracker (TRT) at the ATLAS experiment with argon and krypton gas mixtures was simulated. The efficiency of transition radiation registration, which is necessary for electron identification, was estimated along with the electron identification capabilities under such conditions.

  20. Radiative and Nonradiative Transitions of the Rare-Earth Ions Tm(3+) and Ho(3+) in Y3AI5O12 and LiYF4

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.; Armagan, Guzin; Dibartolo, Baldassare; Modlin, Edward A.

    1995-01-01

    The optical spectra of rare earth ions in solids arise primarily from electric and magnetic dipole transitions between stark split multiplets of the 4f(sup N) electronic configuration. Electric dipole transitions are parity forbidden between levels of the 4f(sup N) configuration, while those of magnetic dipole origin are allowed. It is known from experiment, however, that the significant contributions to the intensities of most transitions are electric dipole in nature. Judd and Ofelt developed the theory of forced electric dipole transitions of rare-earth ions. This study is devoted to determining electric dipole transition probabilities and branching ratios for Tm(3+) and Ho(3+) ions in Yttrium Aluminum Garnet (YAG) and Yttrium Lithium Fluoride (YLF) using the theory of Judd and Ofelt. The radiative rates determined from the Judd-Ofelt analysis are used with measured lifetimes to find nonradiative rates of relaxation.

  1. Radiative and Nonradiative Transitions of the Rare-Earth Ions Tm(3+) and Ho(3+) in Y3AI5O12 and LiYF4

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.; Armagan, Guzin; Dibartolo, Baldassare; Modlin, Edward A.

    1995-01-01

    The optical spectra of rare earth ions in solids arise primarily from electric and magnetic dipole transitions between stark split multiplets of the 4f(sup N) electronic configuration. Electric dipole transitions are parity forbidden between levels of the 4f(sup N) configuration, while those of magnetic dipole origin are allowed. It is known from experiment, however, that the significant contributions to the intensities of most transitions are electric dipole in nature. Judd and Ofelt developed the theory of forced electric dipole transitions of rare-earth ions. This study is devoted to determining electric dipole transition probabilities and branching ratios for Tm(3+) and Ho(3+) ions in Yttrium Aluminum Garnet (YAG) and Yttrium Lithium Fluoride (YLF) using the theory of Judd and Ofelt. The radiative rates determined from the Judd-Ofelt analysis are used with measured lifetimes to find nonradiative rates of relaxation.

  2. Reaction rate theory of radiation exposure:Effects of dose rate on mutation frequency

    NASA Astrophysics Data System (ADS)

    Bando, Masako; Nakamura, Issei; Manabe, Yuichiro

    2014-03-01

    We revisit the linear no threshold (LNT) hypothesis deduced from the prominent works done by H. J. Muller for the DNA mutation induced by the artificial radiation and by W. L. Russell and E. M. Kelly for that of mega-mouse experiments, developing a new kinetic reaction theory. While the existing theoretical models primarily rely on the dependence of the total dose D on the mutation frequency, the key ingredient in our theory is the dose rate d(t) that accounts for decrease in the mutation rate during the time course of the cellular reactions. The general form for the mutation frequency with the constant dose rate d is simply expressed as, dFm(t)/dt = A - BFm(t) , with A =a0 +a1(d +deff) and B =b0 +b1(d +deff) . We discuss the solution for a most likely case with B > 0 ; Fm(t) = [A/B -Fm(0) ] (1 -e-Bt) +Fm(0) with the control value Fm(0) . We show that all the data of mega-mouse experiments by Russel with different dose rates fall on the universal scaling function Φ(τ) ≡ [Fm(τ) -Fm(0) ]/[ A / B -Fm(0) ] = 1 - exp(- τ) with scaled time τ = Bt . The concept of such a scaling rule provides us with a strong tool to study different species in a unified manner.

  3. Monochromatic coherent grating transition radiation in sub-THz frequency range

    NASA Astrophysics Data System (ADS)

    Naumenko, G.; Aryshev, A.; Potylitsyn, A.; Shevelev, M.; Sukhikh, L.; Terunuma, N.; Urakawa, J.

    2017-07-01

    Grating transition radiation (GTR) emitted by electrons interacting with a diffraction grating was experimentally confirmed. This radiation appears when a charge intersects the grating at some inclination angle θ between the main grating plane and the charge velocity vector. If the condition θ = 0 is fulfilled the GTR tends to the conventional Smith-Purcell radiation. In this report we present the experimental investigation of spectral and orientation dependencies of a coherent GTR in sub-THz wavelength region emitted by 8 MeV electron at KEK LUCX facility. The coherent GTR spectral line shapes up to 5th diffraction order were measured for different inclination angles (θ = 0-25 deg) with the grating period 4 mm. A pair of room-temperature Schottky barrier diode (SBD) detectors with sensitivity bands 60-90 GHz and 320-460 GHz were used. The estimation of radiation frequency dependence on the inclination angle using the dispersion relation justifies the usage of different narrow-band SBD detectors to investigate different diffraction orders of coherent GTR spectral lines. It was shown that the bandwidth of the GTR spectral lines decreases with the diffraction order. The comparison with coherent transition radiation in the same frequency range showed that the brightness of both radiation mechanisms are comparable.

  4. Energy levels and transition rates for the boron isoelectronic sequence: Si X, Ti XVIII - Cu XXV

    NASA Astrophysics Data System (ADS)

    Jönsson, P.; Ekman, J.; Gustafsson, S.; Hartman, H.; Karlsson, L. B.; du Rietz, R.; Gaigalas, G.; Godefroid, M. R.; Froese Fischer, C.

    2013-11-01

    Relativistic configuration interaction (RCI) calculations are performed for 291 states belonging to the configurations 1s22s22p, 1s22s2p2, 1s22p3, 1s22s23l, 1s22s2p3l, 1s22p23l, 1s22s24l', 1s22s2p4l', and 1s22p24l' (l = 0,1,2 and l' = 0,1,2,3) in boron-like ions Si X and Ti XVIII to Cu XXV. Electron correlation effects are represented in the wave functions by large configuration state function (CSF) expansions. States are transformed from jj-coupling to LS-coupling, and the LS-percentage compositions are used for labeling the levels. Radiative electric dipole transition rates are given for all ions, leading to massive data sets. Calculated energy levels are compared with other theoretical predictions and crosschecked against the Chianti database, NIST recommended values, and other observations. The accuracy of the calculations are high enough to facilitate the identification of observed spectral lines. Research supported in part by the Swedish Research council and the Swedish Institute. Part of this work was supported by the Communauté française of Belgium, the Belgian National Fund for Scientific Research (FRFC/IISN Convention) and by the IUAP-Belgian State Science Policy (BriX network P7/12).Tables of energy levels and transition rates (Tables 3-19) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/559/A100

  5. Octupole deformation in sup 221 Fr; E1 transition rates

    SciTech Connect

    Liang, C.F.; Peghaire, A. ); Sheline, R.K. )

    1990-07-10

    Experimental data following the alpha decay of{sup 225}Ac are interpreted in terms of a spectroscopy in {sup 221}Fr consistent with octupole deformation. However, the measured E1 transition probabilities suggest that the low lying bands in {sup 221}Fr are considerably more mixed than in nuclei with slightly higher mass number. It is suggested that this mixing of states in {sup 221}Fr is indicative of the partial collapse of Nilsson-like orbitals into more degenerate shell model orbitals.

  6. Radiation-enhanced thermal diffusion of transition metal and rare earth ions into II-VI semiconductors

    NASA Astrophysics Data System (ADS)

    Martinez, Alán.; Williams, Lamario; Gafarov, Ozarfar; Martyshkin, Dmitry; Fedorov, Vladimir; Mirov, Sergey

    2015-02-01

    We report on study of gamma radiation-enhanced thermal diffusion of Transition Metal and Rare Earth ions into IIVI semiconductor crystals. ZnSe and ZnS samples with of iron thin film deposited on one facet were sealed in evacuated quartz ampoules at 10-3 Torr. The crystals were annealed for 14 days at 950°C under γ-irradiation from 60Co source. The irradiation dose rates of 43.99 R/s, 1.81 R/s were varied by distance between 60Co source and furnaces. For comparison, the samples were also annealed without irradiation at the same temperature. The spatial distributions of transition metal were measured by absorption of focused laser radiation at 5T2-5E mid-IR transitions of iron ions. In addition, samples of ZnSe were similarly sealed in evacuated quartz ampoules in the presence of Praseodymium metal and annealed at 950°C under 43.99 R/s and 0 R/s and the diffusion lengths and Pr concentrations were compared. The γ-irradiation results in better intrusion of the iron ions from the metal film and increase of the diffusion length at ~25%, while Praseodymium diffusion is dramatically enhanced by γ-irradiation during the annealing process.

  7. Performance of the Time Expansion Chamber / Transition Radiation Detector in PHENIX Experiment at RHIC

    NASA Astrophysics Data System (ADS)

    Luiz Silva, Cesar

    2004-10-01

    The Time Expansion Chamber / Transition Radiation Detector (TEC/TRD) in the PHENIX Experiment at RHIC measures ionization losses (dE/dX) and transition radiation from charged particles produced by beam collisions. It is designed to perform tracking and identification for charged particles on very high particle multiplicity environment. The TEC/TRD consists of 24 wire chambers readout on both sides filled with recycled Xe-based gas mixture. This wire chamber configuration, besides providing measurements of ionization losses for charged particles, can absorb X-Ray photons generated by transition radiation from incident particles with γ>1000 crossing fiber radiators placed at the entrance of the chambers. This allows TEC/TRD to distinguish electrons from the huge pion signal produced over a broad momentum range (1GeV/c

  8. Revisiting radiative deep-level transitions in CuGaSe{sub 2} by photoluminescence

    SciTech Connect

    Spindler, Conrad Regesch, David; Siebentritt, Susanne

    2016-07-18

    Recent defect calculations suggest that the open circuit voltage of CuGaSe{sub 2} solar cells can be limited by deep intrinsic electron traps by Ga{sub Cu} antisites and their complexes with Cu-vacancies. To gain experimental evidence, two radiative defect transitions at 1.10 eV and 1.24 eV are characterized by steady-state photoluminescence on epitaxial-grown CuGaSe{sub 2} thin films. Cu-rich samples are studied, since they show highest crystal quality, exciton luminescence, and no potential fluctuations. Variations of the laser intensity and temperature dependent measurements suggest that emission occurs from two deep donor-like levels into the same shallow acceptor. At 10 K, power-law exponents of 1 (low excitation regime) and 1/2 (high excitation regime) are observed identically for both transitions. The theory and a fitting function for the double power law is derived. It is concluded that the acceptor becomes saturated by excess carriers which changes the exponent of all transitions. Activation energies determined from the temperature quenching depend on the excitation level and show unexpected values of 600 meV and higher. The thermal activation of non-radiative processes can explain the distortion of the ionization energies. Both the deep levels play a major role as radiative and non-radiative recombination centers for electrons and can be detrimental for photovoltaic applications.

  9. Revisiting radiative deep-level transitions in CuGaSe2 by photoluminescence

    NASA Astrophysics Data System (ADS)

    Spindler, Conrad; Regesch, David; Siebentritt, Susanne

    2016-07-01

    Recent defect calculations suggest that the open circuit voltage of CuGaSe2 solar cells can be limited by deep intrinsic electron traps by GaCu antisites and their complexes with Cu-vacancies. To gain experimental evidence, two radiative defect transitions at 1.10 eV and 1.24 eV are characterized by steady-state photoluminescence on epitaxial-grown CuGaSe2 thin films. Cu-rich samples are studied, since they show highest crystal quality, exciton luminescence, and no potential fluctuations. Variations of the laser intensity and temperature dependent measurements suggest that emission occurs from two deep donor-like levels into the same shallow acceptor. At 10 K, power-law exponents of 1 (low excitation regime) and 1/2 (high excitation regime) are observed identically for both transitions. The theory and a fitting function for the double power law is derived. It is concluded that the acceptor becomes saturated by excess carriers which changes the exponent of all transitions. Activation energies determined from the temperature quenching depend on the excitation level and show unexpected values of 600 meV and higher. The thermal activation of non-radiative processes can explain the distortion of the ionization energies. Both the deep levels play a major role as radiative and non-radiative recombination centers for electrons and can be detrimental for photovoltaic applications.

  10. Glass transition in thaumatin crystals revealed through temperature-dependent radiation-sensitivity measurements.

    PubMed

    Warkentin, Matthew; Thorne, Robert E

    2010-10-01

    The temperature-dependence of radiation damage to thaumatin crystals between T = 300 and 100 K is reported. The amount of damage for a given dose decreases sharply as the temperature decreases from 300 to 220 K and then decreases more gradually on further cooling below the protein-solvent glass transition. Two regimes of temperature-activated behavior were observed. At temperatures above ∼200 K the activation energy of 18.0 kJ mol(-1) indicates that radiation damage is dominated by diffusive motions in the protein and solvent. At temperatures below ∼200 K the activation energy is only 1.00 kJ mol(-1), which is of the order of the thermal energy. Similar activation energies describe the temperature-dependence of radiation damage to a variety of solvent-free small-molecule organic crystals over the temperature range T = 300-80 K. It is suggested that radiation damage in this regime is vibrationally assisted and that the freezing-out of amino-acid scale vibrations contributes to the very weak temperature-dependence of radiation damage below ∼80 K. Analysis using the radiation-damage model of Blake and Phillips [Blake & Phillips (1962), Biological Effects of Ionizing Radiation at the Molecular Level, pp. 183-191] indicates that large-scale conformational and molecular motions are frozen out below T = 200 K but become increasingly prevalent and make an increasing contribution to damage at higher temperatures. Possible alternative mechanisms for radiation damage involving the formation of hydrogen-gas bubbles are discussed and discounted. These results have implications for mechanistic studies of proteins and for studies of the protein glass transition. They also suggest that data collection at T ≃ 220 K may provide a viable alternative for structure determination when cooling-induced disorder at T = 100 is excessive.

  11. Image Formation by Incoherent and Coherent Transition Radiation from Flat and Rough Surfaces

    SciTech Connect

    Stupakov, Gennady; /SLAC

    2012-03-01

    In this paper we derive equations for the image formation of transverse profile of a relativistic beam obtained by means of optical transition radiation (OTR) from flat and rough metal surfaces. The motivation behind this study lies in the desire to suppress coherent transition radiation (COTR) observed in experiments at modern free electron lasers. The physical mechanism behind the problem of COTR is that the OTR is predominantly radiated at small angles of order of 1/{gamma} where {gamma} is the relativistic factor of the beam. This means that the transverse formation size of the image is of order of {bar {lambda}}{gamma} where {bar {lambda}} = {lambda}/2{pi} with {lambda} the radiation wavelength. For relativistic beams this can be comparable or even exceed the transverse size of the beam, which would mean that the image of the beam has very little to do with its transverse profile. It is fortuitous, however, that the incoherent image is formed by adding radiation energy of electrons and results in the transverse formation size being of order of {bar {lambda}}/{theta}{sub a}, with {theta}{sub a} is the aperture angle of the optical system. The COTR image, in contrast, is formed by adding electromagnetic field of electrons, and leads to the formation size {bar {lambda}}{gamma}. In situations when the COTR intensity exceeds that of OTR the COTR imaging makes the diagnostic incapable of measuring the beam profile.

  12. Effect of a finite ionization rate on the radiative heating of outer planet atmospheric entry probes

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1981-01-01

    The influence of finite rate ionization in the inviscid gas just behind the stagnation shock wave on the radiation heating of probes entering the hydrogen helium atmospere of the major planets was investigated. At the present time, there is disagreement as to whether the radiative flux increases or decreases relative to its equilibrium value when finite rate ionization is considered. Leibowitz and Kuo content that the finite rate ionization in the hydrogen gas just behind the shock wave reduces the radiative flux to the probe, whereas Tiwari and Szema predict that it increases the radiative flux. The radiation modeling used in the calculations of both pairs of these investigators was reviewed. It is concluded that finite rate ionization in the inviscid region of the shock layer should reduce the cold wall radiative heating below the values predicted by equilibrium chemistry assumptions.

  13. Growth rate and transition to turbulence of a gas curtain

    SciTech Connect

    Vorobieff, P.; Rightley, P.; Benjamin, R.

    1997-09-01

    The authors conduct shock-tube experiments to investigate Richtmyer-Meshkov (RM) instability of a narrow curtain of heavy gas (SF{sub 6}) embedded in lighter gas (air). Initial perturbations of the curtain can be varied, producing different flow patterns in the subsequent evolution of the curtain. Multiple-exposure video flow visualization provides images of the growth of the instability and its transition to turbulence, making it possible to extract quantitative information such as the width of the perturbed curtain. They demonstrate that the width of the curtain with initial perturbation on the downstream side is non-monotonic. As the initial perturbation undergoes phase inversion, the width of the curtain actually decreases before beginning to grow as the RM instability evolves.

  14. Effects of correlation in transition radiation of super-short electron bunches

    NASA Astrophysics Data System (ADS)

    Danilova, D. K.; Tishchenko, A. A.; Strikhanov, M. N.

    2017-07-01

    The effect of correlations between electrons in transition radiation is investigated. The correlation function is obtained with help of the approach similar to the Debye-Hückel theory. The corrections due to correlations are estimated to be near 2-3% for the parameters of future projects SINBAD and FLUTE for bunches with extremely small lengths (∼1-10 fs). For the bunches with number of electrons about ∼ 2.5 ∗1010 and more, and short enough that the radiation would be coherent, the corrections due to correlations are predicted to reach 20%.

  15. Multilevel radiative thermal memory realized by the hysteretic metal-insulator transition of vanadium dioxide

    SciTech Connect

    Ito, Kota Nishikawa, Kazutaka; Iizuka, Hideo

    2016-02-01

    Thermal information processing is attracting much interest as an analog of electronic computing. We experimentally demonstrated a radiative thermal memory utilizing a phase change material. The hysteretic metal-insulator transition of vanadium dioxide (VO{sub 2}) allows us to obtain a multilevel memory. We developed a Preisach model to explain the hysteretic radiative heat transfer between a VO{sub 2} film and a fused quartz substrate. The transient response of our memory predicted by the Preisach model agrees well with the measured response. Our multilevel thermal memory paves the way for thermal information processing as well as contactless thermal management.

  16. Radiative transitions in charm-strange meson from Nf = 2 twisted mass lattice QCD

    NASA Astrophysics Data System (ADS)

    Li, Ning; Wu, Ya-Jie

    2016-07-01

    We present an exploratory study on the radiative transition for the charm-strange meson: Ds∗→ D sγ using Nf = 2 twisted mass lattice quantum chromodynamics gauge configurations. The form factor for Ds meson is also determined. The simulation is performed on lattices with lattice spacings a = 0.067 fm and lattice size 323 × 64, and a = 0.085 fm and lattice size 243 × 48, respectively. Our numerical results for radiative decay width and the experimental data overlap within the margin of error.

  17. Multilevel radiative thermal memory realized by the hysteretic metal-insulator transition of vanadium dioxide

    NASA Astrophysics Data System (ADS)

    Ito, Kota; Nishikawa, Kazutaka; Iizuka, Hideo

    2016-02-01

    Thermal information processing is attracting much interest as an analog of electronic computing. We experimentally demonstrated a radiative thermal memory utilizing a phase change material. The hysteretic metal-insulator transition of vanadium dioxide (VO2) allows us to obtain a multilevel memory. We developed a Preisach model to explain the hysteretic radiative heat transfer between a VO2 film and a fused quartz substrate. The transient response of our memory predicted by the Preisach model agrees well with the measured response. Our multilevel thermal memory paves the way for thermal information processing as well as contactless thermal management.

  18. Evidence for microbunching "sidebands" in a saturated free-electron laser using coherent optical transition radiation.

    PubMed

    Lumpkin, A H; Dejus, R; Lewellen, J W; Berg, W; Biedron, S; Borland, M; Chae, Y C; Erdmann, M; Huang, Z; Kim, K-J; Li, Y; Milton, S V; Moog, E; Rule, D W; Sajaev, V; Yang, B X

    2002-06-10

    We report the first measurements of z-dependent coherent optical transition radiation (COTR) due to electron-beam microbunching at high gains ( >10(4)) including saturation of a self-amplified spontaneous emission free-electron laser (FEL). In these experiments the fundamental wavelength was near 530 nm, and the COTR spectra exhibit the transition from simple spectra to complex spectra ( 5% spectral width) after saturation. The COTR intensity growth and angular distribution data are reported as well as the evidence for transverse spectral dependencies and an "effective" core of the beam being involved in microbunching.

  19. ATLAS Transition Radiation Tracker (TRT): Straw tubes for tracking and particle identification at the Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Mindur, Bartosz

    2017-02-01

    The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three inner detector tracking subsystems and consists of ∼300,000 thin-walled drift tubes (;straw tubes;) that are 4 mm in diameter. The TRT system provides ∼ 30 space points with ∼130 micron resolution for charged tracks with | η | < 2 and pT > 0.5 GeV / c . The TRT also provides electron identification capability by detecting transition radiation (TR) X-ray photons in an Xe-based working gas mixture. Compared to Run 1, the LHC beams now provide a higher centre of mass energy (13 TeV), more bunches with a reduced spacing (25 ns), and more particles in each bunch leading to very challenging, higher occupancies in the TRT. Significant modifications of the TRT detector have been made for LHC Run 2 mainly to improve response to the expected much higher rate of hits and to mitigate leaks of the Xe-based active gas mixture. The higher rates required changes to the data acquisition system and introduction of validity gate to reject out-of-time hits. Many gas leaks were repaired and the gas system was modified to use a cheaper Ar-based gas mixture in some channels. A likelihood method was introduced to optimise the TRT electron identification.

  20. 10 CFR 35.2070 - Records of surveys for ambient radiation exposure rate.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Records of surveys for ambient radiation exposure rate. 35.2070 Section 35.2070 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2070 Records of surveys for ambient radiation exposure rate. A licensee shall retain a record of...

  1. 10 CFR 35.2070 - Records of surveys for ambient radiation exposure rate.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Records of surveys for ambient radiation exposure rate. 35.2070 Section 35.2070 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2070 Records of surveys for ambient radiation exposure rate. A licensee shall retain a record of...

  2. 10 CFR 35.2070 - Records of surveys for ambient radiation exposure rate.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Records of surveys for ambient radiation exposure rate. 35.2070 Section 35.2070 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2070 Records of surveys for ambient radiation exposure rate. A licensee shall retain a record of...

  3. 10 CFR 35.2070 - Records of surveys for ambient radiation exposure rate.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Records of surveys for ambient radiation exposure rate. 35.2070 Section 35.2070 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2070 Records of surveys for ambient radiation exposure rate. A licensee shall retain a record of...

  4. 10 CFR 35.2070 - Records of surveys for ambient radiation exposure rate.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Records of surveys for ambient radiation exposure rate. 35.2070 Section 35.2070 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records § 35.2070 Records of surveys for ambient radiation exposure rate. A licensee shall retain a record of...

  5. Glass transition in thaumatin crystals revealed through temperature-dependent radiation-sensitivity measurements

    SciTech Connect

    Warkentin, Matthew Thorne, Robert E.

    2010-10-01

    Radiation damage to protein crystals exhibits two regimes of temperature-activated behavior between T = 300 and 100 K, with a crossover at the protein glass transition near 200 K. These results have implications for mechanistic studies of proteins and for structure determination when cooling to T = 100 K creates excessive disorder. The temperature-dependence of radiation damage to thaumatin crystals between T = 300 and 100 K is reported. The amount of damage for a given dose decreases sharply as the temperature decreases from 300 to 220 K and then decreases more gradually on further cooling below the protein-solvent glass transition. Two regimes of temperature-activated behavior were observed. At temperatures above ∼200 K the activation energy of 18.0 kJ mol{sup −1} indicates that radiation damage is dominated by diffusive motions in the protein and solvent. At temperatures below ∼200 K the activation energy is only 1.00 kJ mol{sup −1}, which is of the order of the thermal energy. Similar activation energies describe the temperature-dependence of radiation damage to a variety of solvent-free small-molecule organic crystals over the temperature range T = 300–80 K. It is suggested that radiation damage in this regime is vibrationally assisted and that the freezing-out of amino-acid scale vibrations contributes to the very weak temperature-dependence of radiation damage below ∼80 K. Analysis using the radiation-damage model of Blake and Phillips [Blake & Phillips (1962 ▶), Biological Effects of Ionizing Radiation at the Molecular Level, pp. 183–191] indicates that large-scale conformational and molecular motions are frozen out below T = 200 K but become increasingly prevalent and make an increasing contribution to damage at higher temperatures. Possible alternative mechanisms for radiation damage involving the formation of hydrogen-gas bubbles are discussed and discounted. These results have implications for mechanistic studies of proteins and for

  6. Kinetics of the iron α -ɛ phase transition at high-strain rates: Experiment and model

    NASA Astrophysics Data System (ADS)

    Amadou, N.; de Resseguier, T.; Brambrink, E.; Vinci, T.; Benuzzi-Mounaix, A.; Huser, G.; Morard, G.; Guyot, F.; Miyanishi, K.; Ozaki, N.; Kodama, R.; Koenig, M.

    2016-06-01

    In this article, we investigate the kinetics of the iron α -ɛ transition under laser-driven ramp compression for deformation rates ranging from 3 to 9 ×107s-1 . As in previous work, we observe a plateau in the rear surface velocity profile at the transition. With increasing deformation rate the transition onset pressure raises from 11 to 25 GPa, while the plateau duration decreases. These kinetic effects are well reproduced by an Avrami-type kinetics model of nucleation and growth with a constant, nanosecond scale completion time, which suggests an isokinetic regime over the explored range of strain rates.

  7. RADIATION THERAPY OF A PRESUMPTIVE URETHRAL TRANSITIONAL CELL CARCINOMA IN AN EASTERN GRAY SQUIRREL (SCIURUS CAROLINENSIS).

    PubMed

    Childs-Sanford, Sara E; St-Vincent, Rachel; Hiss, Anne

    2015-12-01

    An adult female Eastern gray squirrel (Sciurus carolinensis), with a previous history of primary renal transitional cell carcinoma treated by nephrectomy, was diagnosed with a metastatic urethral transitional cell carcinoma (TCC) utilizing the veterinary bladder tumor antigen test in combination with other noninvasive diagnostic tests. The squirrel was treated with piroxicam and external beam radiation therapy given in 18 treatments over 30 days to achieve a total of 54 gray. Mild to moderate side effects from the pelvic irradiation were self-limiting and easily managed. Resolution of clinical signs was achieved for approximately 6 mo until recurrence of metastasis. This report represents the first published account of both TCC and external beam radiation therapy in an Eastern gray squirrel.

  8. First observation of the point spread function of optical transition radiation.

    PubMed

    Karataev, Pavel; Aryshev, Alexander; Boogert, Stewart; Howell, David; Terunuma, Nobuhiro; Urakawa, Junji

    2011-10-21

    We represent the first experimental observation of the point spread function (PSF) of optical transition radiation (OTR) performed at KEK-Accelerator Test Facility extraction line. We have demonstrated that the PSF vertical polarization component has a central minimum with a two lobe distribution. However, the distribution width varied significantly with wavelength. We assume that we observed a severe effect from spherical or chromatic aberrations which are not taken into account in any existing theoretical model. We believe that the result of this work will encourage theoreticians to continue developing the theory as it is important for various transition radiation applications. Nonuniform distribution of the OTR PSF creates an opportunity for developing a submicrometer transverse beam size monitor.

  9. Radiation driven epithelial-mesenchymal transition is mediated by Notch signaling in breast cancer

    PubMed Central

    Suh, Yongjoon; Yoo, Ki-Chun; Cui, Yan-Hong; Kim, Min-Jung; Lee, Hae-June; Kim, In-Gyu; Lee, Su-Jae

    2016-01-01

    Epithelial to mesenchymal transition (EMT) is developmental process associated with cancer metastasis. Here, we found that breast carcinoma cells adopt epithelial-to-mesenchymal transition (EMT) in response to fractionated-radiation. Importantly, we show that Notch signaling is highly activated in fractionally-irradiated tumors as compared to non-irradiated tumors that are accompanied by an EMT. Moreover, we uncovered the mechanism of Notch-driven EMT, in which Notch enhanced EMT through IL-6/JAK/STAT3 signaling axis in mammary tumor cells. Collectively, we present converging evidence from our studies that Notch2 is a critical mediator of radiation-induced EMT and responsible for induced malignant tumor growth. PMID:27462787

  10. First Observation of the Point Spread Function of Optical Transition Radiation

    NASA Astrophysics Data System (ADS)

    Karataev, Pavel; Aryshev, Alexander; Boogert, Stewart; Howell, David; Terunuma, Nobuhiro; Urakawa, Junji

    2011-10-01

    We represent the first experimental observation of the point spread function (PSF) of optical transition radiation (OTR) performed at KEK-Accelerator Test Facility extraction line. We have demonstrated that the PSF vertical polarization component has a central minimum with a two lobe distribution. However, the distribution width varied significantly with wavelength. We assume that we observed a severe effect from spherical or chromatic aberrations which are not taken into account in any existing theoretical model. We believe that the result of this work will encourage theoreticians to continue developing the theory as it is important for various transition radiation applications. Nonuniform distribution of the OTR PSF creates an opportunity for developing a submicrometer transverse beam size monitor.

  11. Single-shot electro-optic sampling of coherent transition radiation at the A0 Photoinjector

    SciTech Connect

    Maxwell, T.J.; Ruan, J.; Piot, P.; Thurman-Keup, R.; /Fermilab

    2011-08-01

    Future collider applications and present high-gradient laser plasma wakefield accelerators operating with picosecond bunch durations place a higher demand on the time resolution of bunch distribution diagnostics. This demand has led to significant advancements in the field of electro-optic sampling over the past ten years. These methods allow the probing of diagnostic light such as coherent transition radiation or the bunch wakefields with sub-picosecond time resolution. Potential applications in shot-to-shot, non-interceptive diagnostics continue to be pursued for live beam monitoring of collider and pump-probe experiments. Related to our developing work with electro-optic imaging, we present results on single-shot electro-optic sampling of the coherent transition radiation from bunches generated at the A0 photoinjector.

  12. Influence of space charge effect in femtosecond electron bunch on coherent transition radiation spectrum

    NASA Astrophysics Data System (ADS)

    Shevelev, M.; Aryshev, A.; Honda, Y.; Terunuma, N.; Urakawa, J.

    2017-07-01

    This paper numerically and experimentally demonstrates the influence of the space charge forces in short electron bunches on the spectrum of coherent transition radiation. To estimate and optimize dimensions of a short electron bunches produced by the KEK LUCX RF gun, ASTRA software was employed. Obtained results indicate that the modification of the femtosecond UV laser pulse transverse profile allows to decrease the space charge forces. The simulation results were confirmed experimentally with the good agreement.

  13. Methodology for estimating radiation dose rates to freshwater biota exposed to radionuclides in the environment

    SciTech Connect

    Blaylock, B.G.; Frank, M.L.; O`Neal, B.R.

    1993-08-01

    The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiation dose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiation doses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiation dose rate to biota to the U.S. Department of Energy`s (DOE`s) recommended dose rate limit of 0.4 mGy h{sup {minus}1} (1 rad d{sup {minus}1}). A dose rate no greater than 0.4 mGy h{sup {minus}1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE`s recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiation dose rate of 0. 1 mGy h{sup {minus}1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic populations should be conducted.

  14. Burning Rate Transitions for HMX Burned as a Binderless Propellant,

    DTIC Science & Technology

    1980-06-01

    have shown that the regression attains velocities up to 6000 cm/s at high pressure , with pressure exponents as low as 0.3, depending on sample...base of the charge, extremely high burn rate propellant (several thou- sand cm/s or more depending on gun pressure and muzzle velocity desired) is...experiments were carried out, the calculated flame heights range from 17 to 700 cm, depending on particle size and pressure . Thus, it is not surprising that

  15. Determination of electron bunch shape using transition radiation and phase-energy measurements

    SciTech Connect

    Crosson, E.R.; Berryman, K.W.; Richman, B.A.

    1995-12-31

    We present data comparing microbunch temporal information obtained from electron beam phase-energy measurements with that obtained from transition radiation auto-correlation measurements. The data was taken to resolve some of the ambiguities in previous transition radiation results. By measuring the energy spectrum of the electron beam as a function of its phase relative to the accelerating field, phase-energy information was extracted. This data was analyzed using tomographic techniques to reconstruct the phase-space distribution assuming an electron energy dependence of E({var_phi}) = E{sub o} + E{sub acc}cos({var_phi}), where E{sub o} is the energy of an electron entering the field, E{sub acc} is the peak energy gain, and {var_phi} is the phase between the crest of the RF wave and an electron. Temporal information about the beam was obtained from the phase space distribution by taking the one dimensional projection along the time axis. We discuss the use of this technique to verify other transition radiation analysis methods.

  16. Coherent transition and diffraction radiation from a bunched 6.1 MeV electron beam

    NASA Astrophysics Data System (ADS)

    Naumenko, G. A.; Aleinik, A. N.; Aryshev, A. S.; Kalinin, B. N.; Potylitsyn, A. P.; Saruev, G. A.; Sharafutdinov, A. F.

    2005-01-01

    The theory of transition radiation (TR) from an ideally conducting infinite target is well known. During the last several years the theory of diffraction radiation (DR) from simple geometry targets has further been developed. In a few experiments coherent TR and coherent DR were used to measure the electron bunch length. However, experimental investigations of coherent TR (or DR) look rather poor for finite size targets. The experimental results of investigation of coherent backward transition radiation (CBTR) and coherent backward diffraction radiation (CBDR) are presented. The intensity of CBTR and CBDR from a finite conducting target for different impact-parameters depending on the target inclination angle θ ( θ-scan) has been investigated using the 6 MeV electron beam of the Tomsk microtron. The model allowing to calculate both TR and DR characteristics for any impact-parameter h (the shortest distance between particle trajectory and target edge) was developed and tested by comparison with experimental results. The calculations were performed for the real experimental conditions. For γλ ≫ h ( γ - Lorentz-factor, λ - TR (DR) wavelength) and large detector bandwidth {γ(λmax-λmin)}/{h}>1 the measured TR angular distribution shows a single maximum only (like DR one) in contrast to a lobe-shaped OTR distribution.

  17. ORAL ISSUE OF THE JOURNAL "USPEKHI FIZICHESKIKH NAUK": Transition radiation: scientific implications and applications in high-energy physics

    NASA Astrophysics Data System (ADS)

    Denisov, Sergei P.

    2007-04-01

    In their pioneering work on transition radiation, Ginzburg and Frank showed for the first time that a charge may radiate electromagnetic waves not only because of its accelerated motion but also because of time variation of the phase velocity of electromagnetic waves in the ambient medium. This result is of very general importance for physics. For example, a charge at rest can radiate in a nonstationary medium. Transition radiation is widely used in high-energy particle detectors, mainly for identification of ultrarelativistic electrons in accelerator and collider experiments.

  18. Extraordinary rates of transition metal ion-mediated ribozyme catalysis

    PubMed Central

    Roychowdhury-Saha, Manami; Burke, Donald H.

    2006-01-01

    In pre-steady-state, fast-quench kinetic analysis, the tertiary-stabilized hammerhead ribozyme “RzB” cleaves its substrate RNA with maximal measured k obs values of ∼3000 min−1 in 1 mM Mn2+ and ∼780 min−1 in 1 mM Mg2+ at 37°C (pH 7.4). Apparent pKa for the catalytic general base is ∼7.8–8.5, independent of the corresponding metal hydrate pKa, suggesting potential involvement of a nucleobase as general base as suggested previously from nucleobase substitution studies. The pH-rate profile is bell-shaped for Cd2+, for which the general catalytic acid has a pKa of 7.3 ± 0.1. Simulations of the pH-rate relation suggest a pKa for the general catalytic acid to be ∼9.5 in Mn2+ and >9.5 in Mg2+. The acid pKa's follow the trend in the pKa of the hydrated metal ions but are displaced by ∼1–2 pH units in the presence of Cd2+ and Mn2+. One possible explanation for this trend is direct metal ion coordination with a nucleobase, which then acts as general acid. PMID:16912216

  19. Laminar and turbulent flow solutions with radiation and ablation injection for Jovian entry. [radiative heating rates for the Galileo probe

    NASA Technical Reports Server (NTRS)

    Kumar, A.; Tiwari, S. N.

    1980-01-01

    Laminar and turbulent flow-field solutions with coupled carbon-phenolic mass injection are presented for the forebody of a probe entering a nominal Jupiter atmosphere. Solutions are obtained for a 35-degree hyperboloid and for a 45-degree spherically blunted cone using a time-dependent, finite-difference method. The radiative heating rates for the coupled laminar flow are significantly reduced as compared to the corresponding no-blowing case; however, for the coupled turbulent flow, it is found that the surface radiative heating rates are substantially increased and often exceed the corresponding no-blowing values. Turbulence is found to have no effect on the surface radiative heating rates for the no-blowing solutions. The present results are compared with the other available solutions, and some additional solutions are presented.

  20. Variations of dose rate observed by MSL/RAD in transit to Mars

    NASA Astrophysics Data System (ADS)

    Guo, Jingnan; Zeitlin, Cary; Wimmer-Schweingruber, Robert F.; Hassler, Donald M.; Posner, Arik; Heber, Bernd; Köhler, Jan; Rafkin, Scot; Ehresmann, Bent; Appel, Jan K.; Böhm, Eckart; Böttcher, Stephan; Burmeister, Sönke; Brinza, David E.; Lohf, Henning; Martin, Cesar; Reitz, Günther

    2015-05-01

    Aims: To predict the cruise radiation environment related to future human missions to Mars, the correlation between solar modulation potential and the dose rate measured by the Radiation Assessment Detector (RAD) has been analyzed and empirical models have been employed to quantify this correlation. Methods: The instrument RAD, onboard Mars Science Laboratory's (MSL) rover Curiosity, measures a broad spectrum of energetic particles along with the radiation dose rate during the 253-day cruise phase as well as on the surface of Mars. With these first ever measurements inside a spacecraft from Earth to Mars, RAD observed the impulsive enhancement of dose rate during solar particle events as well as a gradual evolution of the galactic cosmic ray (GCR) induced radiation dose rate due to the modulation of the primary GCR flux by the solar magnetic field, which correlates with long-term solar activities and heliospheric rotation. Results: We analyzed the dependence of the dose rate measured by RAD on solar modulation potentials and estimated the dose rate and dose equivalent under different solar modulation conditions. These estimations help us to have approximate predictions of the cruise radiation environment, such as the accumulated dose equivalent associated with future human missions to Mars. Conclusions: The predicted dose equivalent rate during solar maximum conditions could be as low as one-fourth of the current RAD cruise measurement. However, future measurements during solar maximum and minimum periods are essential to validate our estimations.

  1. Rate limiting mechanism of transition metal gettering in multicrystalline silicon

    SciTech Connect

    McHugo, S.A.; Thompson, A.C.; Imaizumi, M.; Hieslmair, H.; Weberr, E.R.

    1997-07-01

    The authors have performed studies on multicrystalline silicon used for solar cells in the as-grown state and after a series of processing and gettering steps. The principal goal of this work is to determine the rate limiting step for metal impurity gettering from multicrystalline silicon with an emphasis on the release of impurities from structural defects. Synchrotron-based x-ray fluorescence mapping was used to monitor the release process. Copper and nickel impurities were found to reside primarily at dislocations in the as-grown state of the material. Short annealing treatments rapidly dissolved the impurity agglomerates. Based on these results and modeling of the dissolution process, copper and nickel is in the form of small agglomerates (< 10 nm) clustered together over micron-scale regions in the as-grown material. Aluminum gettering further disintegrated the agglomerates to below the sensitivity of the system, 2--5 nm in radii. No significant barrier to release of copper or nickel from dislocations was observed.

  2. Coherent regime and far-to-near-field transition for radiative heat transfer

    NASA Astrophysics Data System (ADS)

    Tsurimaki, Yoichiro; Chapuis, Pierre-Olivier; Okajima, Junnosuke; Komiya, Atsuki; Maruyama, Shigenao; Vaillon, Rodolphe

    2017-01-01

    Radiative heat transfer between two semi-infinite parallel media is analyzed in the transition zone between the near-field and the classical macroscopic, i.e. incoherent far-field, regimes of thermal radiation, first for model gray materials and then for real metallic (Al) and dielectric (SiC) materials. The presence of a minimum in the flux-distance curve is observed for the propagative component of the radiative heat transfer coefficient, and in some cases for the total coefficient, i.e. the sum of the propagative and evanescent components. At best this reduction can reach 15% below the far-field limit in the case of aluminum. The far-to-near-field regime taking place for the distance range between the near-field and the classical macroscopic regime involves a coherent far-field regime. One of its limits can be practically defined by the distance at which the incoherent far-field regime breaks down. This separation distance below which the standard theory of incoherent thermal radiation cannot be applied anymore is found to be larger than the usual estimate based on Wien's law and varies as a function of temperature. The aforementioned effects are due to coherence, which is present despite the broadband spectral nature of thermal radiation, and has a stronger impact for reflective materials.

  3. Very High Dose-Rate Radiobiology and Radiation Therapy for Lung Cancer

    DTIC Science & Technology

    2015-02-01

    AWARD NUMBER: W81XWH-14-1-0014 TITLE: Very High Dose-Rate Radiobiology and Radiation Therapy for Lung Cancer PRINCIPAL INVESTIGATOR: Peter Maxim...TITLE AND SUBTITLE ery High Dose-Rate Radiobiology and Radiation Therapy for Lung Cancer 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-14-1-0014 5c...1 Contract number: W81XWH-14-1-0014 Title: Very High Dose-Rate Radiobiology and Radiation Therapy for Lung Cancer Principal Investigator: Peter G

  4. Interpreting impedance spectra of organic photovoltaic cells—Extracting charge transit and recombination rates

    SciTech Connect

    Mullenbach, Tyler K.; Zou, Yunlong; Holmes, Russell J.; Holst, James

    2014-09-28

    Impedance spectroscopy has been widely used to extract the electron-hole recombination rate constant in organic photovoltaic cells (OPVs). This technique is typically performed on OPVs held at open-circuit. Under these conditions, the analysis is simplified with recombination as the only pathway for the decay of excess charge carriers; transit provides no net change in the charge density. In this work, we generalize the application and interpretation of impedance spectroscopy for bulk heterojunction OPVs at any operating voltage. This, in conjunction with reverse bias external quantum efficiency measurements, permits the extraction of both recombination and transit rate constants. Using this approach, the transit and recombination rate constants are determined for OPVs with a variety of electron donor-acceptor pairings and compositions. It is found that neither rate constant individually is sufficient to characterize the efficiency of charge collection in an OPV. It is demonstrated that a large recombination rate constant can be accompanied by a large transit rate constant, thus fast recombination is not necessarily detrimental to OPV performance. Extracting the transit and recombination rate constants permits a detailed understanding of how OPV architecture and processing conditions impact the transient behavior of charge carriers, elucidating the origin of optimum device configurations.

  5. Glass transition in thaumatin crystals revealed through temperature-dependent radiation-sensitivity measurements

    PubMed Central

    Warkentin, Matthew; Thorne, Robert E.

    2010-01-01

    The temperature-dependence of radiation damage to thaumatin crystals between T = 300 and 100 K is reported. The amount of damage for a given dose decreases sharply as the temperature decreases from 300 to 220 K and then decreases more gradually on further cooling below the protein-solvent glass transition. Two regimes of temperature-activated behavior were observed. At temperatures above ∼200 K the activation energy of 18.0 kJ mol−1 indicates that radiation damage is dominated by diffusive motions in the protein and solvent. At temperatures below ∼200 K the activation energy is only 1.00 kJ mol−1, which is of the order of the thermal energy. Similar activation energies describe the temperature-dependence of radiation damage to a variety of solvent-free small-molecule organic crystals over the temperature range T = 300–80 K. It is suggested that radiation damage in this regime is vibrationally assisted and that the freezing-out of amino-acid scale vibrations contributes to the very weak temperature-dependence of radiation damage below ∼80 K. Analysis using the radiation-damage model of Blake and Phillips [Blake & Phillips (1962 ▶), Biological Effects of Ionizing Radiation at the Molecular Level, pp. 183–191] indicates that large-scale conformational and molecular motions are frozen out below T = 200 K but become increasingly prevalent and make an increasing contribution to damage at higher temperatures. Possible alternative mechanisms for radiation damage involving the formation of hydrogen-gas bubbles are discussed and discounted. These results have implications for mechanistic studies of proteins and for studies of the protein glass transition. They also suggest that data collection at T ≃ 220 K may provide a viable alternative for structure determination when cooling-induced disorder at T = 100 is excessive. PMID:20944242

  6. Failures Of CMOS Devices At Low Radiation-Dose Rates

    NASA Technical Reports Server (NTRS)

    Goben, Charles A.; Price, William E.

    1990-01-01

    Method for obtaining approximate failure-versus-dose-rate curves derived from experiments on failures of SGS 4007 complementary metal oxide/semiconductor (CMOS) integrated circuits irradiated by Co60 and Cs137 radioactive sources.

  7. Comparison of radiative-convective models with constant and pressure-dependent lapse rates

    NASA Technical Reports Server (NTRS)

    Hummel, J. R.; Kuhn, W. R.

    1981-01-01

    One of the most commonly used models for studying climatic processes is the convective adjustment radiation model. In current radiation models, stable temperature profiles are maintained with a convective adjustment in which the temperature lapse rate is set equal to a critical lapse rate whenever the computed lapse rates exceed the critical value. First introduced by Manabe and Strickler (1964), a variety of convective adjustment models are now in use. It is pointed out that on a global scale, moist adiabatic processes, and thus moist adiabatic lapse rates, approximate the atmospheric temperature profile. Comparisons of profiles from a one-dimensional-radiative-convective model have been made using the conventional 6.5 K/km as the critical lapse rate and the pressure-dependent moist adiabatic lapse rates. For a clear sky and a single effective cloud the surface temperatures are 1 to 3 K higher with the constant 6.5 K/km critical lapse rate.

  8. A test of whether rates of speciation were unusually high during the Cambrian radiation.

    PubMed

    Lieberman, B S

    2001-08-22

    The Cambrian radiation represents an interval when nearly 20 animal phyla appear in the fossil record in a short geological time span; however, whether this radiation also represents a period of extremely rapid speciation remains unclear. Here, a stochastic framework is used to test the null hypothesis that diversity changes in one of the dominant Early Cambrian groups, the olenelloid trilobites, could be produced by tempos of speciation known to have operated during later time periods. Two continuous-time models, the Yule model and the birth and death process model, and one discrete-time model, the Bienaymé-Galton-Watson branching process model, were used. No statistical evidence for uniquely high rates of speciation during the radiation in these trilobites was found when the continuous-time models were used with low or moderate extinction rates, the rates typically associated with the Cambrian radiation, although the p values are fairly low or, in one case, significant when high extinction rates were used. However, rates of speciation were higher than the average Phanerozoic rates of speciation. The discrete-time model produced equivocal results: either rates were unusually high or the model is inapplicable during the Cambrian radiation. This suggests that there was nothing unique about evolutionary processes relating to the tempo of speciation during the Cambrian radiation.

  9. Measurement of the radiative and nonradiative decay rates of single CdSe nanocrystals through a controlled modification of their spontaneous emission.

    PubMed

    Brokmann, X; Coolen, L; Dahan, M; Hermier, J P

    2004-09-03

    We present a simple method to measure the radiative and nonradiative recombination rates of individual fluorescent emitters at room temperature. By placing a single molecule successively close and far from a dielectric interface and simultaneously measuring its photoluminescence decay and its orientation, both the radiative and nonradiative recombination rates can be determined. For CdSe nanocrystals, our results demonstrate that the fluorescence quantum efficiency, determined at the single-molecule level, is 98% in average, far above the value expected from conventional ensemble experiments. The bidimensional nature of the transition dipole is also directly evidenced from a single-particle measurement.

  10. Methodology for Estimating Radiation Dose Rates to Freshwater Biota Exposed to Radionuclides in the Environment

    SciTech Connect

    Blaylock, B.G.

    1993-01-01

    The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiation dose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiation doses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiation dose rate to biota to the U.S. Department of Energy's (DOE's) recommended dose rate limit of 0.4 mGy h{sup -1} (1 rad d{sup -1}). A dose rate no greater than 0.4 mGy h{sup -1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE's recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). The literature identifies the developing eggs and young of some species of teleost fish as the most radiosensitive organisms. DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiation dose rate of 0.1 mGy h{sup -1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic populations should be

  11. Effect of a finite ionization rate on the radiative heating of outer planet atmospheric entry probes

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1982-01-01

    The influence of finite rate ionization in the inviscid gas just behind the stagnation shock wave on the radiative heating of probes entering the hydrogen-helium atmosphere of the major plants was investigated. Two opposing conclusions were reached as to how the ionization rate assumption affects the radiative transfer. Hydrogen-helium shock waves with a cold nonblowing wall boundary condition at the probe heat shield are emphasized. The study is limited to the stagnation shock layer.

  12. Monitoring of electron bunch length by using Terahertz coherent transition radiation

    NASA Astrophysics Data System (ADS)

    Su, Xiaolu; Yan, Lixin; Du, Yingchao; Zhang, Zhen; Zhou, Zheng; Wang, Dong; Zheng, Lianmin; Tian, Qili; Huang, Wenhui; Tang, Chuanxiang

    2017-07-01

    In this paper, ultrashort bunch length monitoring was demonstrated based on Terahertz (THz) coherent transition radiation (CTR) in Tsinghua Thomson scattering X-ray (TTX) source. The radiation produced by electron bunch is split into three paths: one of them is used to detect the total energy, while the other two paths are filtered with different THz band-pass filters before detection. The bunch length variation can be obtained by calculating the ratio between the filtered energy and the total energy. The bunch is compressed by a chicane and via changing the current of chicane, the ratio of filtered energy and total energy changed correspondingly. It is a simple supplemental approach to monitor the bunch length during beam conditioning and facility operation. Bunch arrival-time jitter and nonlinear effects in chicane are observed in the experiment during the measurement of filtered energy and total energy.

  13. Particle-in-Cell Simulations of THz Coherent Transition Radiation from Laser-Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Bruhwiler, D.; Messmer, P.; Cary, J. R.; Leemans, W. P.; Esarey, E.; Schroeder, C.; Geddes, C.; van Tilborg, J.; Shadwick, B.

    2004-11-01

    Laser wakefield accelerator (LWFA) concepts are characterized by ultra-high gradients and ultra-short (tens of fs) bunch lengths. Non-invasive bunch-length diagnostics, at or very near the plasma exit, are key to continuing the rapid advances in LWFA technology. These short bunches can radiate strongly at THz frequencies via coherent transition radiation (CTR) as they exit the plasma [1]. Careful measurements of the THz spectrum will provide the necessary bunch-length diagnostic [2], once the effects of various secondary complications have been quantified. Particle-in-cell simulations, using the VORPAL code [3] are being used to characterize CTR emitted from a self-modulated LWFA. The status of this on-going work will be presented. [1] Wim Leemans et al., Phys. Rev. Lett. 91, 074802-1 (2003). [2] C. Schroeder et al., Phys. Rev. E 69, 016501 (2004). [3] C. Nieter and J. Cary, J. Comp. Phys. 196, 488 (2004).

  14. Estimation of the critical glass transition rate and the inorganic glass thickness

    NASA Astrophysics Data System (ADS)

    Belousov, O. K.

    2009-12-01

    Procedures are described for calculating the components of a new equation obtained to estimate critical glass transition rate R c . Reported data on R c are used to calculate critical shear frequency ν t, g( m), and a technique of its calculation using absolute entropy and elastic constants is presented. Procedures for calculating the energy of defect formation in amorphous substances H ν and for estimating glass transition temperature T g are described. It is shown that the ratio H ν / q (where q = N A k BΔ T m-g , N A is Avogadro’s number, k B is the Boltzmann constant, and Δ T m-g is the difference between the melting and glass transition temperatures) can be used to estimate critical glass transition rate R c and critical glass thickness h c .

  15. Reconciling transition path time and rate measurements in reactions with large entropic barriers

    NASA Astrophysics Data System (ADS)

    Makarov, Dmitrii E.

    2017-02-01

    Recent experiments and simulation studies showed that protein/DNA folding barriers inferred from folding rates or from potentials of mean force are often much higher than the barriers estimated from the distributions of transition path times. Here a toy model is used to explain a possible origin of this effect: It is shown that when the transition in question involves an entropic barrier, the one-dimensional Langevin model commonly used to interpret experimental data, while adequately predicting the transition rate, fails to describe the properties of the subset of the trajectories that form the transition path ensemble; the latter may still be describable in terms of a one-dimensional model, but with a different potential, just as observed experimentally.

  16. Reconciling transition path time and rate measurements in reactions with large entropic barriers.

    PubMed

    Makarov, Dmitrii E

    2017-02-21

    Recent experiments and simulation studies showed that protein/DNA folding barriers inferred from folding rates or from potentials of mean force are often much higher than the barriers estimated from the distributions of transition path times. Here a toy model is used to explain a possible origin of this effect: It is shown that when the transition in question involves an entropic barrier, the one-dimensional Langevin model commonly used to interpret experimental data, while adequately predicting the transition rate, fails to describe the properties of the subset of the trajectories that form the transition path ensemble; the latter may still be describable in terms of a one-dimensional model, but with a different potential, just as observed experimentally.

  17. Determination of hyperfine-induced transition rates from observations of a planetary nebula.

    PubMed

    Brage, Tomas; Judge, Philip G; Proffitt, Charles R

    2002-12-31

    Observations of the planetary nebula NGC3918 made with the STIS instrument on the Hubble Space Telescope reveal the first unambiguous detection of a hyperfine-induced transition 2s2p 3P(o)(0)-->2s2 1S0 in the berylliumlike emission line spectrum of N IV at 1487.89 A. A nebular model allows us to confirm a transition rate of 4x10(-4) sec(-1)+/-33% for this line. The measurement represents the first independent confirmation of the transition rate of hyperfine-induced lines in low ionization stages, and it provides support for the techniques used to compute these transitions for the determination of very low densities and isotope ratios.

  18. Care Transitions in Long-term Care and Acute Care: Health Information Exchange and Readmission Rates.

    PubMed

    Yeaman, Brian; Ko, Kelly J; Alvarez del Castillo, Rodolfo

    2015-09-30

    Care transitions between settings are a well-known cause of medical errors. A key component of transition is information exchange, especially in long-term care (LTC). However, LTC is behind other settings in adoption of health information technologies (HIT). In this article, we provide some brief background information about care transitions in LTC and concerns related to technology. We describe a pilot project using HIT and secure messaging in LTC to facilitate electronic information exchange during care transitions. Five LTC facilities were included, all located within Oklahoma and serviced by the same regional health system. The study duration was 20 months. Both inpatient readmission and return emergency department (ED) visit rates were lower than baseline following implementation. We provide discussion of positive outcomes, lessons learned, and limitations. Finally, we offer implications for practice and research for implementation of HIT and information exchange across care settings that may contribute to reduction in readmission rates in acute care and ED settings.

  19. The effect of dose rate and adriamycin on the tolerance of thoracic radiation in mice

    SciTech Connect

    Sherman, D.M.; Carabell, S.C.; Belli, J.A.

    1982-01-01

    Radiation damage to the lung may be a predisposing factor in the development of interstitial pneumonitis in patients undergoing total body radiation and subsequent bone marrow transplantation in the treatment of leukemia. Adriamycin has been used in conjunction with bone marrow transplantation, and has also been shown to interact with radiation. This experiment was designed to study the effects of pre-administration of adriamycin on the radiation tolerance of the lung and esophagus. Mice were irradiated at 5 rad; 15 rad or 70 rad per minute to the upper body, 24 hours or 7 days after adriamycin. Oral esophageal death occurred within one month; thus, deaths within 30 days were ascribed to this mechanism. In comparison, deaths because of pulmonary toxicity occurred later. Those between 30 and 160 days were ascribed to this mechanism. In the absence of adriamycin, a dose rate effect was found for the lung and confirmed for the upper gastrointestinal tract. The dose of radiation necessary to give pulmonary and gastrointestinal toxicity was markedly reduced when adriamycin was administered 24 hours before radiation. If seven days were allowed between adriamycin and radiation there was still an effect seen only at the high dose rate of the esophagus while for the lung at the high dose rate and for both systems at low dose rate no significant drug effects were noted. The dose rate effect is still seen after the drug, but it is reduced. These studies indicate that adriamycin given shortly before can significantly increase the oral esophageal and pulmonary toxicity of radiation and can practically abrogate the sparing effect of dose rate. This must be considered when clinically using total body radiation and adriamycin in preparation for bone marrow transplantation. (JMT)

  20. The effect of dose rate and adriamycin on the tolerance of thoracic radiation in mice

    SciTech Connect

    Sherman, D.B.; Carabell, S.C.; Belli, J.A.; Hellman, S.

    1982-01-01

    Radiation damage to the lung may be a predisposing factor in the development of interstitial pneumonitis in patients undergoing total body radiation and subsequent bone marrow transplantation in the treatment of leukemia. Adriamycin has been used in conjunction with bone marrow transplantation, and has also been shown to interact with radiation. This experiment was designed to study the effects of pre-administration of adriamycin on the radiation tolerance of the lung and esophagus. Mice were irradiated at 5 rad; 15 rad or 70 rad per minute to the upper body, 24 hours or 7 days after adriamycin. Oral esophageal death occurred within one month; thus, deaths within 30 days were ascribed to this mechanism. In comparison, deaths because of pulmonary toxicity occured later. Those between 30 and 160 days were ascribed to this mechanism. In the absence of adriamycin, a dose rate effect was found for the lung and confirmed for the upper gastrointestinal tract.The dose of radiation necessary to give pulmonary and gastrointestinal toxicity was markedly reduced when adriamycin was administered 24 hours before radiation. If seven days were allowed between adriamycin and radiation there was still an effect seen only at the high dose rate for the esophagus while for the lung at the high dose rate and for both systems at low dose rate no significant drug effects were noted. The dose rate effect is still seen after the drug, but it is reduced. These studies indicate that adriamycin given shortly before can significantly increase the oral esophageal and pulmonary toxicity of radiation and can practically abrogate the sparing effect of dose rate. This must be considered when clinically using total body radiation and adriamycin in preparation for bone marrow transplantation. (JMT)

  1. Effect of Thermal Fluctuations on the Radiative Rate in Core/Shell Quantum Dots.

    PubMed

    Balan, Arunima D; Eshet, Hagai; Olshansky, Jacob H; Lee, Youjin V; Rabani, Eran; Alivisatos, A Paul

    2017-03-08

    The effect of lattice fluctuations and electronic excitations on the radiative rate is demonstrated in CdSe/CdS core/shell spherical quantum dots (QDs). Using a combination of time-resolved photoluminescence spectroscopy and atomistic simulations, we show that lattice fluctuations can change the radiative rate over the temperature range from 78 to 300 K. We posit that the presence of the core/shell interface plays a significant role in dictating this behavior. We show that the other major factor that underpins the change in radiative rate with temperature is the presence of higher energy states corresponding to electron excitation into the shell. These effects should be present in other core/shell samples and should also affect other excited state rates, such as the rate of Auger recombination or the rate of charge transfer.

  2. Geranylgeranylacetone alleviates radiation-induced lung injury by inhibiting epithelial-to-mesenchymal transition signaling.

    PubMed

    Kim, Joong-Sun; Son, Yeonghoon; Jung, Myung-Gu; Jeong, Ye Ji; Kim, Sung-Ho; Lee, Su-Jae; Lee, Yoon-Jin; Lee, Hae-June

    2016-06-01

    Radiation-induced lung injury (RILI) involves pneumonitis and fibrosis, and results in pulmonary dysfunction. Moreover, RILI can be a fatal complication of thoracic radiotherapy. The present study investigated the protective effect of geranylgeranlyacetone (GGA), an inducer of heat shock protein (HSP)70, on RILI using a C57BL/6 mouse model of RILI developing 6 months subsequent to exposure to 12.5 Gy thoracic radiation. GGA was administered 5 times orally prior and subsequent to radiation exposure, and the results were assessed by histological analysis and western blotting. The results show that late RILI was alleviated by GGA treatment, possibly through the suppression of epithelial‑to‑mesenchymal transition (EMT) marker expression. Based on histological examination, orally administered GGA during the acute phase of radiation injury not only significantly inhibited pro‑surfactant protein C (pro‑SPC) and vimentin expression, but also preserved E‑cadherin expression 6 months after irradiation‑induced injury of the lungs. GGA induced HSP70 and inhibited EMT marker expression in L132 human lung epithelial cells following IR. These data suggest that the prevention of EMT signaling is a key cytoprotective effect in the context of RILI. Thus, HSP70‑inducing drugs, such as GGA, could be beneficial for protection against RILI.

  3. Observation of coherently enhanced tunable narrow-band terahertz transition radiation from a relativistic sub-picosecond electron bunch train

    SciTech Connect

    Piot, P.; Sun, Y. -E; Maxwell, T. J.; Ruan, J.; Lumpkin, A. H.; Rihaoui, M. M.; Thurman-Keup, R.

    2011-06-27

    We experimentally demonstrate the production of narrow-band (δf/f ~ =20% at f ~ = 0.5 THz) THz transition radiation with tunable frequency over [0.37, 0.86] THz. The radiation is produced as a train of sub-picosecond relativistic electron bunches transits at the vacuum-aluminum interface of an aluminum converter screen. In addition, we show a possible application of modulated beams to extend the dynamical range of a popular bunch length diagnostic technique based on the spectral analysis of coherent radiation.

  4. Monitoring of radiation dose rates around a clinical nuclear medicine site

    NASA Astrophysics Data System (ADS)

    Shao, Chia-Ho; Lu, Cheng-Chang; Chen, Tou-Rong; Weng, Jui-Hung; Kao, Pan-Fu; Dong, Shang-Lung; Chou, Ming-Jen

    2014-11-01

    The monitoring of radiation dose around the nuclear medicine site is an important study issue. In this study, TLD-100H radiation dosimeters were used to measure the ambient radiation dose rates around a clinical nuclear medicine site in order to investigate the latent hot zones of radiation exposure. Results of this study showed that the radiation doses measured from all piping and storage systems were comparable to the background dose. A relatively high dose was observed at the single bend point of waste water piping of the PET/CT. Another important finding was the unexpected high dose rates observed at the non-restricted waiting area (NRWA) of SPECT. To conclude, this study provides useful information for further determination of an appropriate dose reduction strategy to achieve the ALARA principle in a clinical nuclear medicine site.

  5. Cloud properties and associated radiative heating rates in the tropical western Pacific

    SciTech Connect

    Mather, Jim H.; McFarlane, Sally A.; Miller, Mark A.; Johnson, Karen L.

    2007-03-01

    Radiative heating of the atmosphere affects cloud evolution on the cloud scale and it influences large-scale vertical motion. Obtaining good estimates of radiative heating rate profiles has been difficult due to a lack of cloud profile observations. The Atmospheric Radiation Measurement (ARM) program has been measuring cloud property distributions at sites around the globe including three in the tropical western Pacific (TWP) region. We have analyzed a month of these remote sensing observations at Manus and Nauru to calculate time series of vertical cloud property profiles and radiative heating rates. This data set will be an important tool for describing radiative processes in the tropics and assessing the simulation of these processes in dynamical models.

  6. Modelling radiation emission in the transition from the classical to the quantum regime

    NASA Astrophysics Data System (ADS)

    Martins, J. L.; Vranic, M.; Grismayer, T.; Vieira, J.; Fonseca, R. A.; Silva, L. O.

    2016-01-01

    An emissivity formula is derived using the generalised Fermi-Weizäcker-Williams method of virtual photons, which accounts for the recoil the charged particle experiences as it emits radiation. It is found that through this derivation the result obtained by Sokolov et al using QED perturbation theory is recovered. The corrected emissivity formula is applied to nonlinear Thomson scattering scenarios in the transition from the classical to the quantum regime for small values of the nonlinear quantum parameter χ. In addition, signatures of the quantum corrections are identified and explored.

  7. High-energy cosmic-ray electrons - A new measurement using transition-radiation detectors

    NASA Technical Reports Server (NTRS)

    Hartmann, G.; Mueller, D.; Prince, T.

    1977-01-01

    A new detector for cosmic-ray electrons, consisting of a combination of a transition-radiation detector and a shower detector, has been constructed, calibrated at accelerator beams, and exposed in a balloon flight under 5 g/sq cm of atmosphere. The design of this instrument and the methods of data analysis are described. Preliminary results in the energy range 9-300 GeV are presented. The energy spectrum of electrons is found to be significantly steeper than that of protons, consistent with a long escape lifetime of cosmic rays in the galaxy.

  8. Transverse beam shape measurements of intense proton beams using optical transition radiation

    SciTech Connect

    Scarpine, Victor E.; /Fermilab

    2012-03-01

    A number of particle physics experiments are being proposed as part of the Department of Energy HEP Intensity Frontier. Many of these experiments will utilize megawatt level proton beams onto targets to form secondary beams of muons, kaons and neutrinos. These experiments require transverse size measurements of the incident proton beam onto target for each beam spill. Because of the high power levels, most beam intercepting profiling techniques will not work at full beam intensity. The possibility of utilizing optical transition radiation (OTR) for high intensity proton beam profiling is discussed. In addition, previous measurements of OTR beam profiles from the NuMI beamline are presented.

  9. Advanced relativistic model potential approach to calculation of radiation transition parameters in spectra of multicharged ions

    NASA Astrophysics Data System (ADS)

    Svinarenko, A. A.; Ignatenko, A. V.; Ternovsky, V. B.; Nikola, V. V.; Seredenko, S. S.; Tkach, T. B.

    2014-11-01

    The combined relativistic energy approach and relativistic many-body perturbation theory with the zeroth order optimized one-particle approximation are used for calculation of the Li-like ions (Z=11-42,69,70) energies and oscillator strengths of radiative transitions from the ground state to the low-excited and Rydberg states, in particular, 2s1/2 - np1/2,3/2, np1/2,3/2- nd3/2,5/2 (n=2-12). A comparison of the calculated oscillator strengths with available theoretical and experimental data is performed.

  10. Progress on the Flash X-Ray Optical Transition Radiation Diagnostic

    SciTech Connect

    Tang, V; Houck, T; Brown, C

    2008-03-30

    This document summarizes the Flash X-Ray accelerator (FXR) optical transition radiation (OTR) spot-size diagnostics efforts in FY07. During this year, new analysis, simulation, and experimental approaches were utilized to interpret OTR spot data from both dielectric foils such as Kapton (VN type) and metal coated foils. Significant new findings of the intricacies involved in the diagnostic and of FXR operational issues were achieved. Geometry and temperature based effects were found to affect the beam image profiles from the OTR foils. These effects must be taken into account in order to deduce accurately the beam current density profile.

  11. RMS Emittance Measurements Using Optical Transition Radiation Interferometry at the Jefferson Lab FEL

    SciTech Connect

    M. A. Holloway; S. V. Benson; W. Brock; J. L. Coleman; D. Douglas; R. Evans; P. Evtushenko; K. Jordan; D. W. Sexton; R. B. Fiorito; P. G. O'Shea; A. G. Shkvarunets

    2007-08-01

    Optical Transition Radiation Interferometry (OTRI) has proven to be effective tool for measuring rms beam divergence. We present rms emittance measurement results of the 115 MeV energy recovery linac at the Thomas Jefferson National Laboratories Free electron Laser using OTRI. OTRI data from both near field beam images and far field angular distribution images give evidence of two spatial and angular distributions within the beam. Using the unique features of OTRI we segregate the two distributions of the beam and estimate separate rms emittance values for each component.

  12. Radiative transition probabilities for all vibrational levels in the X 1Sigma(+) state of HF

    NASA Technical Reports Server (NTRS)

    Zemke, Warren T.; Stwalley, William C.; Langhoff, Stephen R.; Valderrama, Giuseppe L.; Berry, Michael J.

    1991-01-01

    Recent analyses have led to an experimentally-based potential energy curve for the ground state of HF which includes nonadiabatic corrections and which joins smoothly to the long-range potential at an accurately determined dissociation limit. Using this potential curve and a new ab initio dipole moment function, accurate radiative transition probabilities among all vibrational levels of the ground state of HF have been calculated for selected rotational quantum numbers. Comparisons of Einstein A spontaneous emission coefficients, dipole moment absorption matrix elements, and Herman-Wallis factors for absorption bands are presented.

  13. Transverse Beam Shape Measurements of Intense Proton Beams Using Optical Transition Radiation

    NASA Astrophysics Data System (ADS)

    Scarpine, Victor E.

    A number of particle physics experiments are being proposed as part of the Department of Energy HEP Intensity Frontier. Many of these experiments will utilize megawatt level proton beams onto targets to form secondary beams of muons, kaons and neutrinos. These experiments require transverse size measurements of the incident proton beam onto target for each beam spill. Because of the high power levels, most beam intercepting profiling techniques will not work at full beam intensity. The possibility of utilizing optical transition radiation (OTR) for high intensity proton beam profiling is discussed. In addition, previous measurements of OTR beam profiles from the NuMI beamline are presented.

  14. Sub-micrometer transverse beam size diagnostics using optical transition radiation

    NASA Astrophysics Data System (ADS)

    Kruchinin, K.; Aryshev, A.; Karataev, P.; Bolzon, B.; Lefevre, T.; Mazzoni, S.; Shevelev, M.; Boogert, S. T.; Nevay, L. J.; Terunuma, N.; Urakawa, J.

    2014-05-01

    Optical transition radiation (OTR) arising when a relativistic charged particle crosses a boundary between two media with different optical properties is widely used as a tool for diagnostics of particle beams in modern accelerator facilities. The resolution of the beam profile monitors based on OTR depends on different effects of the optical system such as spherical and chromatic aberrations and diffraction. In this paper we present a systematic study of the different optical effects influencing the OTR beam profile monitor resolution. Obtained results have shown that such monitors can be used for sub-micrometer beam profile diagnostics. Further improvements and studies of the monitor are discussed.

  15. A novel method for sub-micrometer transverse electron beam size measurements using optical transition radiation

    NASA Astrophysics Data System (ADS)

    Aryshev, A.; Boogert, S. T.; Howell, D.; Karataev, P.; Terunuma, N.; Urakawa, J.

    2010-06-01

    Optical Transition Radiation (OTR) appearing when a charged particle crosses a boundary between two media with different dielectric properties has widely been used as a tool for transverse profile measurements of charged particle beams in various facilities worldwide. The resolution of the monitor is defined by so-called Point Spread Function (PSF), source distribution generated by a single electron and projected by an optical system onto a screen. In this paper we represent the development of a novel sub-micrometre electron beam profile monitor based on the measurements of the PSF structure. The first experimental results are presented and future plans on the optimization of the monitor are discussed

  16. Effects of transverse electron beam size on transition radiation angular distribution

    NASA Astrophysics Data System (ADS)

    Chiadroni, E.; Castellano, M.; Cianchi, A.; Honkavaara, K.; Kube, G.

    2012-05-01

    In this paper we consider the effect of the transverse electron beam size on the Optical Transition Radiation (OTR) angular distribution in case of both incoherent and coherent emission. Our results confute the theoretical argumentations presented first in Optics Communications 211, 109 (2002), which predicts a dependence of the incoherent OTR angular distribution on the beam size and emission wavelength. We present here theoretical and experimental data not only to validate the well-established Ginzburg-Frank theory, but also to show the impact of the transverse beam size in case of coherent emission.

  17. Solar radiation increases suicide rate after adjusting for other climate factors in South Korea.

    PubMed

    Jee, Hee-Jung; Cho, Chul-Hyun; Lee, Yu Jin; Choi, Nari; An, Hyonggin; Lee, Heon-Jeong

    2017-03-01

    Previous studies have indicated that suicide rates have significant seasonal variations. There is seasonal discordance between temperature and solar radiation due to the monsoon season in South Korea. We investigated the seasonality of suicide and assessed its association with climate variables in South Korea. Suicide rates were obtained from the National Statistical Office of South Korea, and climatic data were obtained from the Korea Meteorological Administration for the period of 1992-2010. We conducted analyses using a generalized additive model (GAM). First, we explored the seasonality of suicide and climate variables such as mean temperature, daily temperature range, solar radiation, and relative humidity. Next, we identified confounding climate variables associated with suicide rate. To estimate the adjusted effect of solar radiation on the suicide rate, we investigated the confounding variables using a multivariable GAM. Suicide rate showed seasonality with a pattern similar to that of solar radiation. We found that the suicide rate increased 1.008 times when solar radiation increased by 1 MJ/m(2) after adjusting for other confounding climate factors (P < 0.001). Solar radiation has a significant linear relationship with suicide after adjusting for region, other climate variables, and time trends. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. Energetic Particle Radiation in Transit to and on the Surface of Mars

    NASA Astrophysics Data System (ADS)

    Reitz, Guenther

    The radiation exposure in space and on planetary surfaces can be calculated with numerical simulations applying different models for the galactic cosmic rays (GCR) and a code that combines radiation transport into the spacecraft or through the atmosphere and finally in the human body. The Mars Science Lab Radiation assessment detector (MSL-RAD) has provided, for the first time, measurements from inside a spacecraft on its way to Mars and, since the landing of the curiosity rover in August 2012, from the surface of Mars. Through MSL-RAD, a unique data set has become available which allows us validating model calculations with respect to their applicability in future mission planning. Commonly used GCR models, such as Badhwar-O'Neill2010, Burger-Usoskin, CREME2009/CREME96, Badhwar-O’Neill 2011 and a model developed by DLR already show considerable differences in calculated particle fluences. The differences arising in the calculated radiation exposure by applying these models were quantified in terms of particle fluence, absorbed dose and dose equivalent rate using different codes for different shielding thicknesses and the cumulative shielding distribution of the MSL transfer vehicle. The calculations are compared with measurement of the Radiation Assessment detector (RAD) of the Mars Science Lab (MSL) on its cruise towards Mars and on the surface. From the dose equivalents measured and calculated estimates of the upper and lower limits for the risks for a human flight to Mars assuming the radiation environment experienced by MSL-RAD are given and discussed.

  19. Storage-ring measurements of hyperfine induced transition rates in berylliumlike ions

    SciTech Connect

    Schippers, Stefan

    2013-07-11

    The status of experimental measurements and theoretical calculations of the hyperfine induced 2s2p{sup 3}P{sub 0}{yields}2s{sup 21}S{sub 0} transition rate in Be-like ions is reviewed. Possible reasons, such as external electromagnetic fields and competing E1M1 two-photon transitions, for presently existing significant discrepancies between experiment and theory are discussed. Finally, directions for future research are outlined.

  20. How do rain drops affect atmospheric radiative fluxes and heating rates?

    NASA Astrophysics Data System (ADS)

    Hill, Peter; Chiu, Christine; Chern, Jiun-Dar; Allan, Richard; Hill, Adrian

    2017-04-01

    General circulation model (GCM) radiation schemes are becoming increasingly sophisticated; the treatment of clouds has become more refined while the number of gases and aerosol species that are represented continues to rise. However, all GCMs continue to ignore the radiative effect of precipitating liquid water (rain). The resulting biases are expected to be small, but they have yet to be quantified. This study aims to provide a first estimate of how rain affects the atmospheric radiation budget at a range of temporal and spatial scales. This is a necessary first step towards determining whether GCM radiation schemes should include rain. We define the rain radiative effect here as the difference between radiative fluxes calculated with and without rain. We perform calculations using the SOCRATES (Suite Of Community Radiative Transfer codes based on Edwards-Slingo) radiative tranfser scheme. Input atmospheric profiles are taken from two weeks (one week during boreal winter and the other during boreal summer) of a Goddard multiscale modelling framework (MMF) simulation. Based on these calculations, we shall quantify and explain how rain affects the transfer of radiation through the atmosphere and thus radiative heating rates and fluxes at both the surface and top of atmosphere.

  1. Transitions in Symptom Cluster Subgroups among Men Undergoing Prostate Cancer Radiation Therapy

    PubMed Central

    Dirksen, Shannon Ruff; Belyea, Michael J.; Wong, William; Epstein, Dana R.

    2014-01-01

    Background Prostate cancer is a common type of cancer worldwide and in the United States. However, little information has been reported on the symptoms of men overtime who receive radiation therapy. Objective Identify subgroups of men at pre-and post radiation therapy on general and treatment-related symptoms and to determine transitions in subgroup membership overtime. Methods Men (n=84) receiving completed questionnaires on fatigue, insomnia, pain, depression, anxiety, and sexual, urinary and bowel problems at pre-and posttreatment. Latent class analysis identified subgroups. One-way ANOVAs determined subgroups differed on symptoms, participant characteristics, and quality of life. Latent transition analysis examined subgroup transitions overtime. Results At pretreatment four subgroups identified: Resilient group with little to no symptom reporting, Adjusted group with moderately high treatment-related symptoms, low insomnia, depression, and anxiety, Distressed group consistently high on most symptoms, and Emerging group with moderately high fatigue, depression, and anxiety with few treatment-related symptoms. At posttreatment similar results to groups at pretreatment: Resilient, Adjusted and Distressed groups with an Impacted group having high pain, insomnia, depression, urinary, and bowel symptoms. Quality of life and participant characteristics further distinguished groups at pre-and posttreatment. Income level predicted a transition in group membership. Conclusions Men can be classified into distinctly different subgroups overtime. Implications for Practice Assessment and intervention with men in subgroups such as Distressed and Emerging before and during treatment may lessen potential for remaining distressed, or moving into Impacted group where symptom severity is high at posttreatment. Interventions to reduce multiple symptoms are vitally needed. PMID:25730597

  2. Polarity and Excursion Transitions: Can they be Adequately Recorded in High-Sedimentation-Rate Marine Sediments?

    NASA Astrophysics Data System (ADS)

    Channell, J. E. T.

    2014-12-01

    Polarity transitions and magnetic excursions have durations of a few thousand years, or less. Transition/excursion records in volcanic sequences are, at best, partial snap-shots of the transition/excursion field. Records from high-sedimentation-rate marine sediments may be more continuous but they are always smoothed by progressive acquisition of detrital remanent magnetization (DRM), and by sampling/measurement limitations. North Atlantic records of the Matuyama-Brunhes (M-B) polarity transition are compared with records of the Iceland Basin excursion (190 ka). Virtual geomagnetic polar (VGP) paths are used to map characteristic magnetization directions during the transition/excursion. Relative paleointensity (RPI) proxies indicate partial recovery of field intensity during the transition/excursion, with RPI minima coinciding with abrupt VGP shifts at the onset and end of the transition/excursion. Discrepancies in VGP paths among holes at the same site, among sites, and a comparison of u-channel and discrete sample measurements, reveal limitations in resolution of the transition/excursion fields. During the M-B polarity transition, VGP clusters appear in the NW Pacific, NE Asia and in the South Atlantic. Similarities in VGP clustering for the M-B boundary and the Iceland Basin excursion imply that the polarity transition and excursion fields had common characteristics. Similarities with the modern non-axial dipole (NAD) field imply that polarity transitions and excursions involve the demise of the Earth's axial dipole relative to the NAD field, and that the NAD field has long-lasting features locked in place by the lowermost mantle.

  3. Mathematical models of tissue stem and transit target cell divisions and the risk of radiation- or smoking-associated cancer.

    PubMed

    Little, Mark P; Hendry, Jolyon H

    2017-02-01

    There is compelling biological data to suggest that cancer arises from a series of mutations in single target cells, resulting in defects in cell renewal and differentiation processes which lead to malignancy. Because much mutagenic damage is expressed following cell division, more-rapidly renewing tissues could be at higher risk because of the larger number of cell replications. Cairns suggested that renewing tissues may reduce cancer risk by partitioning the dividing cell populations into lineages comprising infrequently-dividing long-lived stem cells and frequently-dividing short-lived daughter transit cells. We develop generalizations of three recent cancer-induction models that account for the joint maintenance and renewal of stem and transit cells, also competing processes of partially transformed cell proliferation and differentiation/apoptosis. We are particularly interested in using these models to separately assess the probabilities of mutation and development of cancer associated with "spontaneous" processes and with those linked to a specific environmental mutagen, specifically ionizing radiation or cigarette smoking. All three models demonstrate substantial variation in cancer risks, by at least 20 orders of magnitude, depending on the assumed number of critical mutations required for cancer, and the stem-cell and transition-cell mutation rates. However, in most cases the conditional probabilities of cancer being mutagen-induced range between 7-96%. The relative risks associated with mutagen exposure compared to background rates are also stable, ranging from 1.0-16.0. Very few cancers, generally <0.5%, arise from mutations occurring solely in stem cells rather than in a combination of stem and transit cells. However, for cancers with 2 or 3 critical mutations, a substantial proportion of cancers, in some cases 100%, have at least one mutation derived from a mutated stem cell. Little difference is made to relative risks if competing processes of

  4. Mathematical models of tissue stem and transit target cell divisions and the risk of radiation- or smoking-associated cancer

    PubMed Central

    Hendry, Jolyon H.

    2017-01-01

    There is compelling biological data to suggest that cancer arises from a series of mutations in single target cells, resulting in defects in cell renewal and differentiation processes which lead to malignancy. Because much mutagenic damage is expressed following cell division, more-rapidly renewing tissues could be at higher risk because of the larger number of cell replications. Cairns suggested that renewing tissues may reduce cancer risk by partitioning the dividing cell populations into lineages comprising infrequently-dividing long-lived stem cells and frequently-dividing short-lived daughter transit cells. We develop generalizations of three recent cancer-induction models that account for the joint maintenance and renewal of stem and transit cells, also competing processes of partially transformed cell proliferation and differentiation/apoptosis. We are particularly interested in using these models to separately assess the probabilities of mutation and development of cancer associated with “spontaneous” processes and with those linked to a specific environmental mutagen, specifically ionizing radiation or cigarette smoking. All three models demonstrate substantial variation in cancer risks, by at least 20 orders of magnitude, depending on the assumed number of critical mutations required for cancer, and the stem-cell and transition-cell mutation rates. However, in most cases the conditional probabilities of cancer being mutagen-induced range between 7–96%. The relative risks associated with mutagen exposure compared to background rates are also stable, ranging from 1.0–16.0. Very few cancers, generally <0.5%, arise from mutations occurring solely in stem cells rather than in a combination of stem and transit cells. However, for cancers with 2 or 3 critical mutations, a substantial proportion of cancers, in some cases 100%, have at least one mutation derived from a mutated stem cell. Little difference is made to relative risks if competing processes of

  5. M-BAND Study of Radiation-Induced Chromosome Aberrations in Human Epithelial Cells: Radiation Quality and Dose Rate Effects

    NASA Technical Reports Server (NTRS)

    Hada, Megumi; Cucinotta, Francis; Wu, Honglu

    2009-01-01

    The advantage of the multicolor banding in situ hybridization (mBAND) technique is its ability to identify both inter- (translocation to unpainted chromosomes) and intra- (inversions and deletions within a single painted chromosome) chromosome aberrations simultaneously. To study the detailed rearrangement of low- and high-LET radiation induced chromosome aberrations in human epithelial cells (CH184B5F5/M10) in vitro, we performed a series of experiments with Cs-137 gamma rays of both low and high dose rates, neutrons of low dose rate and 600 MeV/u Fe ions of high dose rate, with chromosome 3 painted with multi-binding colors. We also compared the chromosome aberrations in both 2- and 3-dimensional cell cultures. Results of these experiments revealed the highest chromosome aberration frequencies after low dose rate neutron exposures. However, detailed analysis of the radiation induced inversions revealed that all three radiation types induced a low incidence of simple inversions. Most of the inversions in gamma-ray irradiated samples were accompanied by other types of intra-chromosomal aberrations but few inversions were accompanied by inter-chromosomal aberrations. In contrast, neutrons and Fe ions induced a significant fraction of inversions that involved complex rearrangements of both inter- and intrachromosomal exchanges. The location of the breaks involved in chromosome exchanges was analyzed along the painted chromosome. The breakpoint distribution was found to be randomly localized on chromosome 3 after neutron or Fe ion exposure, whereas non-random distribution with clustering breakpoints was observed after -ray exposure. Our comparison of chromosome aberration yields between 2- and 3-dimensional cell cultures indicated a significant difference for gamma exposures, but not for Fe ion exposures. These experimental results indicated that the track structure of the radiation and the cellular/chromosome structure can both affect radiation-induced chromosome

  6. M-BAND Study of Radiation-Induced Chromosome Aberrations in Human Epithelial Cells: Radiation Quality and Dose Rate Effects

    NASA Technical Reports Server (NTRS)

    Hada, Megumi; Cucinotta, Francis; Wu, Honglu

    2009-01-01

    The advantage of the multicolor banding in situ hybridization (mBAND) technique is its ability to identify both inter- (translocation to unpainted chromosomes) and intra- (inversions and deletions within a single painted chromosome) chromosome aberrations simultaneously. To study the detailed rearrangement of low- and high-LET radiation induced chromosome aberrations in human epithelial cells (CH184B5F5/M10) in vitro, we performed a series of experiments with Cs-137 gamma rays of both low and high dose rates, neutrons of low dose rate and 600 MeV/u Fe ions of high dose rate, with chromosome 3 painted with multi-binding colors. We also compared the chromosome aberrations in both 2- and 3-dimensional cell cultures. Results of these experiments revealed the highest chromosome aberration frequencies after low dose rate neutron exposures. However, detailed analysis of the radiation induced inversions revealed that all three radiation types induced a low incidence of simple inversions. Most of the inversions in gamma-ray irradiated samples were accompanied by other types of intra-chromosomal aberrations but few inversions were accompanied by inter-chromosomal aberrations. In contrast, neutrons and Fe ions induced a significant fraction of inversions that involved complex rearrangements of both inter- and intrachromosomal exchanges. The location of the breaks involved in chromosome exchanges was analyzed along the painted chromosome. The breakpoint distribution was found to be randomly localized on chromosome 3 after neutron or Fe ion exposure, whereas non-random distribution with clustering breakpoints was observed after -ray exposure. Our comparison of chromosome aberration yields between 2- and 3-dimensional cell cultures indicated a significant difference for gamma exposures, but not for Fe ion exposures. These experimental results indicated that the track structure of the radiation and the cellular/chromosome structure can both affect radiation-induced chromosome

  7. Titan-like exoplanets: Variations in geometric albedo and effective transit height with haze production rate

    NASA Astrophysics Data System (ADS)

    Checlair, Jade; McKay, Christopher P.; Imanaka, Hiroshi

    2016-09-01

    Extensive studies characterizing Titan present an opportunity to study the atmospheric properties of Titan-like exoplanets. Using an existing model of Titan's atmospheric haze, we computed geometric albedo spectra and effective transit height spectra for six values of the haze production rate (zero haze to twice present) over a wide range of wavelengths (0.2-2 μm). In the geometric albedo spectra, the slope in the UV-visible changes from blue to red when varying the haze production rate values from zero to twice the current Titan value. This spectral feature is the most effective way to characterize the haze production rates. Methane absorption bands in the visible-NIR compete with the absorbing haze, being more prominent for smaller haze production rates. The effective transit heights probe a region of the atmosphere where the haze and gas are optically thin and that is thus not effectively probed by the geometric albedo. The effective transit height decreases smoothly with increasing wavelength, from 376 km to 123 km at 0.2 and 2 μm, respectively. When decreasing the haze production rate, the methane absorption bands become more prominent, and the effective transit height decreases with a steeper slope with increasing wavelength. The slope of the geometric albedo in the UV-visible increases smoothly with increasing haze production rate, while the slope of the effective transit height spectra is not sensitive to the haze production rate other than showing a sharp rise when the haze production rate increases from zero. We conclude that geometric albedo spectra provide the most sensitive indicator of the haze production rate and the background Rayleigh gas. Our results suggest that important and complementary information can be obtained from the geometric albedo and motivates improvements in the technology for direct imaging of nearby exoplanets.

  8. Titan-Like Exoplanets: Variations in Geometric Albedo and Effective Transit Height with Haze Production Rate

    NASA Technical Reports Server (NTRS)

    Checlair, Jade; McKay, Christopher P.; Imanaka, Hiroshi

    2016-01-01

    Extensive studies characterizing Titan present an opportunity to study the atmospheric properties of Titan-like exoplanets. Using an existing model of Titan's atmospheric haze, we computed geometric albedo spectra and effective transit height spectra for six values of the haze production rate (zero haze to twice present) over a wide range of wavelengths (0.2-2 microns). In the geometric albedo spectra, the slope in the UV-visible changes from blue to red when varying the haze production rate values from zero to twice the current Titan value. This spectral feature is the most effective way to characterize the haze production rates. Methane absorption bands in the visible-NIR compete with the absorbing haze, being more prominent for smaller haze production rates. The effective transit heights probe a region of the atmosphere where the haze and gas are optically thin and that is thus not effectively probed by the geometric albedo. The effective transit height decreases smoothly with increasing wavelength, from 376 km to 123 km at 0.2 and 2 microns, respectively. When decreasing the haze production rate, the methane absorption bands become more prominent, and the effective transit height decreases with a steeper slope with increasing wavelength. The slope of the geometric albedo in the UV-visible increases smoothly with increasing haze production rate, while the slope of the effective transit height spectra is not sensitive to the haze production rate other than showing a sharp rise when the haze production rate increases from zero. We conclude that geometric albedo spectra provide the most sensitive indicator of the haze production rate and the background Rayleigh gas. Our results suggest that important and complementary information can be obtained from the geometric albedo and motivates improvements in the technology for direct imaging of nearby exoplanets.

  9. Application of validated radiation model in flame spread rate over solid fuels

    NASA Astrophysics Data System (ADS)

    Ivisic, Ivan

    In this thesis the radiative effects of opposed flow flames spreading over solid fuels are discussed as well as the coupling of a radiation and CFD program. The coupled programs are used to show the radiative heat transfer mechanisms and how they affect the flame globally. A radiation program is used to calculate radiation properties of the flame such as the heat flux distribution, net heat flow, and mean Plank absorptivity constant for a particular flame. The radiation program imports the temperature fields from a CFD program. Trends in the mean Plank absorptivity constant with varying ambient conditions are analyzed and an application of the radiation program to simulate a physical radiometer is demonstrated for a test case. The CFD program can import radiation results to help improve the accuracy of the simulation. A script was written to automate the update process to produce more accurate results for flame simulations. Flux distributions, stability and relative error are analyzed to show the coupled programs are producing results within an acceptable error. Trends in error and stability are discussed and stable regions with low enough error are determined. The coupled programs are used to gather data on flame spread rate and find differences in flame structure and properties of neglecting certain radiation mechanisms. No radiation included produced the hottest fastest moving flame, while no gas to surface radiation produced the coolest flame. Including the gas to surface radiation produced a slightly hotter faster moving flame. This trend was studied across different opposed flow velocities and sample widths. The radiative heat fluxes are analyzed for the cases as well. All the flame simulations in this thesis were run for a microgravity, 21% oxygen, and PMMA fuel.

  10. Transitional regimes of natural convection in a differentially heated cubical cavity under the effects of wall and molecular gas radiation

    NASA Astrophysics Data System (ADS)

    Soucasse, L.; Rivière, Ph.; Soufiani, A.; Xin, S.; Le Quéré, P.

    2014-02-01

    The transition to unsteadiness and the dynamics of weakly turbulent natural convection, coupled to wall or gas radiation in a differentially heated cubical cavity with adiabatic lateral walls, are studied numerically. The working fluid is air with small contents of water vapor and carbon dioxide whose infrared spectral radiative properties are modelled by the absorption distribution function model. A pseudo spectral Chebyshev collocation method is used to solve the flow field equations and is coupled to a direct ray tracing method for radiation transport. Flow structures are identified by means of either the proper orthogonal decomposition or the dynamic mode decomposition methods. We first retrieve the classical mechanism of transition to unsteadiness without radiation, characterized by counter-rotating streamwise-oriented vortices generated at the exit of the vertical boundary layers. Wall radiation through a transparent medium leads to a homogenization of lateral wall temperatures and the resulting transition mechanism is similar to that obtained with perfectly conducting lateral walls. The transition is due to an unstable stratification upstream the vertical boundary layers and is characterized by periodically oscillating transverse rolls of axis perpendicular to the main flow. When molecular gas radiation is accounted for, no periodic solution is found and the transition to unsteadiness displays complex structures with chimneys-like rolls whose axes are again parallel to the main flow. The origin of this instability is probably due to centrifugal forces, as suggested previously for the case without radiation. Above the transition to unsteadiness, at Ra = 3 × 108, it is shown that both wall and gas radiation significantly intensify turbulent fluctuations, decrease the thermal stratification in the core of the cavity, and increase the global circulation.

  11. Transitional regimes of natural convection in a differentially heated cubical cavity under the effects of wall and molecular gas radiation

    SciTech Connect

    Soucasse, L.; Rivière, Ph.; Soufiani, A.; Xin, S.

    2014-02-15

    The transition to unsteadiness and the dynamics of weakly turbulent natural convection, coupled to wall or gas radiation in a differentially heated cubical cavity with adiabatic lateral walls, are studied numerically. The working fluid is air with small contents of water vapor and carbon dioxide whose infrared spectral radiative properties are modelled by the absorption distribution function model. A pseudo spectral Chebyshev collocation method is used to solve the flow field equations and is coupled to a direct ray tracing method for radiation transport. Flow structures are identified by means of either the proper orthogonal decomposition or the dynamic mode decomposition methods. We first retrieve the classical mechanism of transition to unsteadiness without radiation, characterized by counter-rotating streamwise-oriented vortices generated at the exit of the vertical boundary layers. Wall radiation through a transparent medium leads to a homogenization of lateral wall temperatures and the resulting transition mechanism is similar to that obtained with perfectly conducting lateral walls. The transition is due to an unstable stratification upstream the vertical boundary layers and is characterized by periodically oscillating transverse rolls of axis perpendicular to the main flow. When molecular gas radiation is accounted for, no periodic solution is found and the transition to unsteadiness displays complex structures with chimneys-like rolls whose axes are again parallel to the main flow. The origin of this instability is probably due to centrifugal forces, as suggested previously for the case without radiation. Above the transition to unsteadiness, at Ra = 3 × 10{sup 8}, it is shown that both wall and gas radiation significantly intensify turbulent fluctuations, decrease the thermal stratification in the core of the cavity, and increase the global circulation.

  12. Sampled-Data Synchronization Analysis of Markovian Neural Networks With Generally Incomplete Transition Rates.

    PubMed

    Zhang, Huaguang; Wang, Junyi; Wang, Zhanshan; Liang, Hongjing

    2017-03-01

    This paper investigates the problem of sampled-data synchronization for Markovian neural networks with generally incomplete transition rates. Different from traditional Markovian neural networks, each transition rate can be completely unknown or only its estimate value is known in this paper. Compared with most of existing Markovian neural networks, our model is more practical because the transition rates in Markovian processes are difficult to precisely acquire due to the limitations of equipment and the influence of uncertain factors. In addition, the time-dependent Lyapunov-Krasovskii functional is proposed to synchronize drive system and response system. By applying an extended Jensen's integral inequality and Wirtinger's inequality, new delay-dependent synchronization criteria are obtained, which fully utilize the upper bound of variable sampling interval and the sawtooth structure information of varying input delay. Moreover, the desired sampled-data controllers are obtained. Finally, two examples are provided to illustrate the effectiveness of the proposed method.

  13. Soluble Dietary Fiber Ameliorates Radiation-Induced Intestinal Epithelial-to-Mesenchymal Transition and Fibrosis.

    PubMed

    Yang, Jianbo; Ding, Chao; Dai, Xujie; Lv, Tengfei; Xie, Tingbing; Zhang, Tenghui; Gao, Wen; Gong, Jianfeng; Zhu, Weiming; Li, Ning; Li, Jieshou

    2016-09-22

    Intestinal fibrosis is a late complication of pelvic radiotherapy. Epithelial-to-mesenchymal transition (EMT) plays an important role in tissue fibrosis. The aim of this study was to examine the effect of soluble dietary fiber on radiation-induced intestinal EMT and fibrosis in a mouse model. Apple pectin (4% wt/wt in drinking water) was administered to wild-type and pVillin-Cre-EGFP transgenic mice with intestinal fibrosis induced by a single dose of abdominal irradiation of 10 Gy. The effects of pectin on intestinal EMT and fibrosis, gut microbiota, and short-chain fatty acid (SCFA) concentration were evaluated. Intestinal fibrosis in late radiation enteropathy showed increased submucosal thickness and subepithelial collagen deposition. Enhanced green fluorescent protein (EGFP)(+)/vimentin(+) and EGFP(+)/α-smooth muscle actin (SMA)(+) coexpressing cells were most clearly observed at 2 weeks after irradiation and gradually decreased at 4 and 12 weeks. Pectin significantly attenuated the thickness of submucosa and collagen deposition at 12 weeks (24.3 vs 27.6 µm in the pectin + radiation-treated group compared with radiation-alone group, respectively, P < .05; 69.0% vs 57.1%, P < .001) and ameliorated EMT at 2 and 4 weeks. Pectin also modulated the intestinal microbiota composition and increased the luminal SCFA concentration. The soluble dietary fiber pectin protected the terminal ileum against radiation-induced fibrosis. This effect might be mediated by altered SCFA concentration in the intestinal lumen and reduced EMT in the ileal epithelium. © 2016 American Society for Parenteral and Enteral Nutrition.

  14. The effect of excipients on the stability and phase transition rate of xylazine hydrochloride and zopiclone.

    PubMed

    Krūkle-Bērziņa, Kristīne; Actiņš, Andris

    2015-03-25

    The compatibility of thermodynamically unstable polymorph of two active pharmaceutical compounds (xylazine hydrochloride form X and zopiclone form C) with different excipients was investigated. The effects of the excipient and its amount in the sample on the thermal properties and possible chemical interactions were studied. The most commonly used excipients in the pharmaceutical industry - calcium carbonate, lactose hydrate, cellulose, magnesium stearate hydrate and calcium stearate hydrate were selected for this study. The dependence of the phase transition rate from an unstable to a more stable polymorph on the excipients and their amounts in the initial sample was analysed at 80°C, and the corresponding phase transition rate constants were calculated.

  15. A high-resolution coherent transition radiation diagnostic for laser-produced electron transport studies (invited)

    SciTech Connect

    Storm, M.; Begishev, I. A.; Brown, R. J.; Mileham, C.; Myatt, J. F.; Nilson, P. M.; Sangster, T. C.; Stoeckl, C.; Theobald, W.; Zuegel, J. D.; Guo, C.; Meyerhofer, D. D.

    2008-10-15

    High-resolution images of the rear-surface optical emission from high-intensity (I{approx}10{sup 19} W/cm{sup 2}) laser illuminated metal foils have been recorded using coherent transition radiation (CTR). CTR is generated as relativistic electrons, generated in high-intensity laser-plasma interactions, exit the target's rear surface and move into vacuum. A transition radiation diagnostic (TRD) records time-integrated images in a 24 nm bandwidth window around {lambda}=529 nm. The optical transmission at {lambda}=1053 nm, the laser wavelength, is 15 orders of magnitude lower than the transmission at the wavelength of interest, {lambda}=527 nm. The detector is a scientific grade charge-coupled device (CCD) camera that operates with a signal-to-noise ratio of 10{sup 3} and has a dynamic range of 10{sup 4}. The TRD has demonstrated a spatial resolution of 1.4 {mu}m over a 1 mm field of view, limited only by the CCD pixel size.

  16. Blackbody radiation shift of the {sup 133}Cs hyperfine transition frequency

    SciTech Connect

    Micalizio, Salvatore; Godone, Aldo; Calonico, Davide; Levi, Filippo; Lorini, Luca

    2004-05-01

    We report the theoretical evaluations of the static scalar polarizability of the {sup 133}Cs ground state and of the blackbody radiation shift induced on the transition frequency between the two hyperfine levels with m{sub F}=0. This shift is of fundamental importance in the evaluation of the accuracy of the primary frequency standards based on atomic fountains and is employed in the realization of the SI second in the International Atomic Time scale at the level of 1x10{sup -15}. Our computed value for the polarizability is {alpha}{sub 0}=(6.600{+-}0.016)x10{sup -39}C m{sup 2}/V in agreement at the level of 1x10{sup -3} with recent theoretical and experimental values. As regards the blackbody radiation shift we find for the relative hyperfine transition frequency {beta}=(-1.49{+-}0.07)x10{sup -14} at T=300 K in agreement with frequency measurements reported by our group and by Bauch and Schroeder [Phys. Rev. Lett. 78, 622 (1997)]. This value is lower by 2x10{sup -15} than that obtained with measurements based on the dc Stark shift and than the value commonly accepted up to now.

  17. Characterization and mitigation of coherent-optical-transition-radiation signals from a compressed electron beam

    NASA Astrophysics Data System (ADS)

    Lumpkin, A. H.; Sereno, N. S.; Berg, W. J.; Borland, M.; Li, Y.; Pasky, S. J.

    2009-08-01

    The Advanced Photon Source (APS) injector complex includes an option for rf photocathode (PC) gun beam injection into the 450-MeV S-band linac. At the 150-MeV point, a four-dipole chicane was used to compress the micropulse bunch length from a few ps to sub-0.5 ps (FWHM). Noticeable enhancements of the optical transition radiation (OTR) signal sampled after the APS chicane were then observed as has been reported in the Linac Coherent Light Source (LCLS) injector commissioning. A far-infrared (FIR) coherent transition radiation detector and interferometer were used to monitor the bunch compression process and correlate the appearance of localized spikes of OTR signal (5 to 10 times brighter than adjacent areas) within the beam-image footprint. We have performed spectral-dependency measurements at 375 MeV with a series of bandpass filters centered in 50-nm increments from 400 to 700 nm and with an imaging spectrometer and observed a broadband enhancement in these spikes. Mitigation concepts of the observed coherent OTR, which exhibits an intensity enhancement in the red part of the visible spectrum as compared to incoherent OTR, are described.

  18. Characterization and mitigation of coherent optical transition radiation signal from a compressed electron beam.

    SciTech Connect

    Lumpkin, A. H.; Sereno, N. S.; Berg, W.; Borland, M.; Li, Y.; Pasky, S. )

    2009-01-01

    The Advanced Photon Source (APS) injector complex includes an option for rf photocathode (PC) gun beam injection into the 450-MeV S-band linac. At the 150-MeV point, a four-dipole chicane was used to compress the micropulse bunch length from a few ps to sub-0.5 ps (FWHM). Noticeable enhancements of the optical transition radiation (OTR) signal sampled after the APS chicane were then observed as has been reported in the Linac Coherent Light Source (LCLS) injector commissioning. A far-infrared (FIR) coherent transition radiation detector and interferometer were used to monitor the bunch compression process and correlate the appearance of localized spikes of OTR signal (5 to 10 times brighter than adjacent areas) within the beam-image footprint. We have performed spectral-dependency measurements at 375 MeV with a series of bandpass filters centered in 50-nm increments from 400 to 700 nm and with an imaging spectrometer and observed a broadband enhancement in these spikes. Mitigation concepts of the observed coherent OTR, which exhibits an intensity enhancement in the red part of the visible spectrum as compared to incoherent OTR, are described.

  19. Relativistic many-body calculations of lifetimes, rates, and line strengths of multipole transitions between 3l-1 4l' states in Ni-like ions

    SciTech Connect

    Safronova, U I; Safronova, A S; Beiersdorfer, P

    2007-10-08

    Transition rates and line strengths are calculated for electric-multipole (E2 and E3) and magnetic-multipole (M1, M2, and M3) transitions between 3s{sup 2}3p{sup 6}3d{sup 10}, 3s{sup 2}3p{sup 6}3d{sup 9}4l, 3s{sup 2}3p{sup 5}3d{sup 10}4l, and 3s3p{sup 6}3d{sup 10}4l states (with 4l = 4s, 4p, 4d, and 4f) in Ni-like ions with the nuclear charges ranging from Z = 34 to 100. Relativistic many-body perturbation theory (RMBPT), including the Breit interaction, is used to evaluate retarded multipole matrix elements. Transition energies used in the calculation of line strengths and transition rates are from second-order RMBPT. Lifetimes of the 3s{sup 2}3p{sup 6}3d{sup 9}4s levels are given for Z = 34-100. Taking into account that calculations were performed in a very broad range of Z, most of the data are presented in graphs as Z-dependencies. The full set of data is given only for Ni-like W ion. In addition, we also give complete results for the 3d4s{sup 3}D{sub 2}-3d4s {sup 3}D{sub 1} magnetic-dipole transition, as the transition may be observed in future experiments, which measure both transition energies and radiative rates. These atomic data are important in the modeling of radiation spectra from Ni-like multiply-charged ions generated in electron beam ion trap experiments as well as for laboratory plasma diagnostics including fusion research.

  20. Development and Transition of the Radiation, Interplanetary Shocks, and Coronal Sources (RISCS) Toolset

    NASA Technical Reports Server (NTRS)

    Spann, James F.; Zank, G.

    2014-01-01

    We outline a plan to develop and transition a physics based predictive toolset called The Radiation, Interplanetary Shocks, and Coronal Sources (RISCS) to describe the interplanetary energetic particle and radiation environment throughout the inner heliosphere, including at the Earth. To forecast and "nowcast" the radiation environment requires the fusing of three components: 1) the ability to provide probabilities for incipient solar activity; 2) the use of these probabilities and daily coronal and solar wind observations to model the 3D spatial and temporal heliosphere, including magnetic field structure and transients, within 10 Astronomical Units; and 3) the ability to model the acceleration and transport of energetic particles based on current and anticipated coronal and heliospheric conditions. We describe how to address 1) - 3) based on our existing, well developed, and validated codes and models. The goal of RISCS toolset is to provide an operational forecast and "nowcast" capability that will a) predict solar energetic particle (SEP) intensities; b) spectra for protons and heavy ions; c) predict maximum energies and their duration; d) SEP composition; e) cosmic ray intensities, and f) plasma parameters, including shock arrival times, strength and obliquity at any given heliospheric location and time. The toolset would have a 72 hour predicative capability, with associated probabilistic bounds, that would be updated hourly thereafter to improve the predicted event(s) and reduce the associated probability bounds. The RISCS toolset would be highly adaptable and portable, capable of running on a variety of platforms to accommodate various operational needs and requirements. The described transition plan is based on a well established approach developed in the Earth Science discipline that ensures that the customer has a tool that meets their needs

  1. Dependence of the width of the glass transition interval on cooling and heating rates.

    PubMed

    Schmelzer, Jürn W P; Tropin, Timur V

    2013-01-21

    In a preceding paper [J. W. P. Schmelzer, J. Chem. Phys. 136, 074512 (2012)], a general kinetic criterion of glass formation has been advanced allowing one to determine theoretically the dependence of the glass transition temperature on cooling and heating rates (or similarly on the rate of change of any appropriate control parameter determining the transition of a stable or metastable equilibrium system into a frozen-in, non-equilibrium state of the system, a glass). In the present paper, this criterion is employed in order to develop analytical expressions for the dependence of the upper and lower boundaries and of the width of the glass transition interval on the rate of change of the external control parameters. It is shown, in addition, that the width of the glass transition range is strongly correlated with the entropy production at the glass transition temperature. The analytical results are supplemented by numerical computations. Analytical results and numerical computations as well as existing experimental data are shown to be in good agreement.

  2. Dependence of the width of the glass transition interval on cooling and heating rates

    NASA Astrophysics Data System (ADS)

    Schmelzer, Jürn W. P.; Tropin, Timur V.

    2013-01-01

    In a preceding paper [J. W. P. Schmelzer, J. Chem. Phys. 136, 074512 (2012), 10.1063/1.3685510], a general kinetic criterion of glass formation has been advanced allowing one to determine theoretically the dependence of the glass transition temperature on cooling and heating rates (or similarly on the rate of change of any appropriate control parameter determining the transition of a stable or metastable equilibrium system into a frozen-in, non-equilibrium state of the system, a glass). In the present paper, this criterion is employed in order to develop analytical expressions for the dependence of the upper and lower boundaries and of the width of the glass transition interval on the rate of change of the external control parameters. It is shown, in addition, that the width of the glass transition range is strongly correlated with the entropy production at the glass transition temperature. The analytical results are supplemented by numerical computations. Analytical results and numerical computations as well as existing experimental data are shown to be in good agreement.

  3. A cloud model-radiative model combination for determining microwave TB-rain rate relations

    NASA Technical Reports Server (NTRS)

    Szejwach, Gerard; Adler, Robert F.; Jobard, Esabelle; Mack, Robert A.

    1986-01-01

    The development of a cloud model-radiative transfer model combination for computing average brightness temperature, T(B), is discussed. The cloud model and radiative transfer model used in this study are described. The relations between rain rate, cloud and rain water, cloud and precipitation ice, and upwelling radiance are investigated. The effects of the rain rate relations on T(B) under different climatological conditions are examined. The model-derived T(B) results are compared to the 92 and 183 GHz aircraft observations of Hakkarinen and Adler (1984, 1986) and the radar-estimated rain rate of Hakkarinen and Adler (1986); good correlation between the data is detected.

  4. Excited meson radiative transitions from lattice QCD using variationally optimized operators

    NASA Astrophysics Data System (ADS)

    Shultz, Christian J.; Dudek, Jozef J.; Edwards, Robert G.; Hadron Spectrum Collaboration

    2015-06-01

    We explore the use of "optimized" operators, designed to interpolate only a single meson eigenstate, in three-point correlation functions with a vector-current insertion. These operators are constructed as linear combinations in a large basis of meson interpolating fields using a variational analysis of matrices of two-point correlation functions. After performing such a determination at both zero and nonzero momentum, we compute three-point functions and are able to study radiative transition matrix elements featuring excited-state mesons. The required two- and three-point correlation functions are efficiently computed using the distillation framework in which there is a factorization between quark propagation and operator construction, allowing for a large number of meson operators of definite momentum to be considered. We illustrate the method with a calculation using anisotopic lattices having three flavors of dynamical quark all tuned to the physical strange quark mass, considering form factors and transitions of pseudoscalar and vector meson excitations. The dependence on photon virtuality for a number of form factors and transitions is extracted, and some discussion of excited-state phenomenology is presented.

  5. Excited meson radiative transitions from lattice QCD using variationally optimized operators

    SciTech Connect

    Shultz, Christian J.; Dudek, Jozef J.; Edwards, Robert G.

    2015-06-02

    We explore the use of 'optimized' operators, designed to interpolate only a single meson eigenstate, in three-point correlation functions with a vector-current insertion. These operators are constructed as linear combinations in a large basis of meson interpolating fields using a variational analysis of matrices of two-point correlation functions. After performing such a determination at both zero and non-zero momentum, we compute three-point functions and are able to study radiative transition matrix elements featuring excited state mesons. The required two- and three-point correlation functions are efficiently computed using the distillation framework in which there is a factorization between quark propagation and operator construction, allowing for a large number of meson operators of definite momentum to be considered. We illustrate the method with a calculation using anisotopic lattices having three flavors of dynamical quark all tuned to the physical strange quark mass, considering form-factors and transitions of pseudoscalar and vector meson excitations. In conclusion, the dependence on photon virtuality for a number of form-factors and transitions is extracted and some discussion of excited-state phenomenology is presented.

  6. Theoretical oscillator strengths, transition probabilities, and radiative lifetimes of levels in Pb V

    SciTech Connect

    Colón, C.; Alonso-Medina, A.; Porcher, P.

    2014-01-15

    Theoretical values of oscillator strengths and transition probabilities for 306 spectral lines arising from the 5d{sup 9}ns(n=7,8,9),5d{sup 9}np(n=6,7),5d{sup 9}6d, and 5d{sup 9} 5f configurations, and radiative lifetimes of 9 levels, of Pb V have been obtained. These values were obtained in intermediate coupling (IC) and using ab initio relativistic Hartree–Fock calculations including core-polarization effects. We use for the IC calculations the standard method of least squares fitting of experimental energy levels by means of computer codes from Cowan. We included in these calculations the 5d{sup 8}6s6p and 5d{sup 8}6s{sup 2} configurations. These calculations have facilitated the identification of the 214.25, 216.79, and 227.66 nm spectral lines of Pb V. In the absence of experimental results of oscillator strengths and transition probabilities, we could not make a direct comparison with our results. However, the Stark broadening parameters calculated from these values are in excellent agreement with experimental widening found in the literature. -- Highlights: •Theoretical values of transition probabilities of Pb V have been obtained. •We use for the IC calculations the standard method of least square. •The parameters calculated from these values are in agreement with the experimental values.

  7. Solubility, phase transition, kinetic ripening and growth rates of porcine pancreatic α-amylase isoenzymes

    NASA Astrophysics Data System (ADS)

    Boistelle, Roland; Astier, Jean Pierre; Marchis-Mouren, Guy; Desseaux, Véronique; Haser, Richard

    1992-09-01

    Two polymorphic modifications, A and B, of porcine pancreatic α-amylase were grown between 4 and 30°C. A and B crystals are made up by two isoenzymes so that four crystal varieties (AI, AII, BI, BII) exist. A and B are easily distinguished due to their typical crystal habits but there is no difference between AI and AII or BI and BII respectively at least as concerns their unit cells, crystal habits and solubilities for instance. On the other hand, the growth rates are somewhat different, even if the overall rate determining step is volume diffusion. The transition temperature between A and B polymorphs is 18°C, A being stable above this temperature. A and B can undergo a phase transition by slightly changing the temperature around the transition point. Kinetic ripening experiments show that ripening can be used for growing larger crystals at the expenses of smaller ones.

  8. Systematic Review of Ambulatory Transitional Care Management (TCM) Visits on Hospital 30-Day Readmission Rates.

    PubMed

    Roper, Karen L; Ballard, Jonathan; Rankin, Wade; Cardarelli, Roberto

    To reduce readmission rates and prevent adverse outcomes after discharge, hospitals have begun implementing "transitional care" initiatives. This systematic review identifies research on the particular set of services now reimbursable by Medicare (transitional care management [TCM]) and evaluates the studies for program effectiveness. Results of 3 databases were screened for peer-reviewed journal articles published between January 2004 and 2015 that report on readmissions of adults in the US health care system under the Medicare TCM bundle. ClinicalTrials.gov was queried for funded studies. Of 969 identified studies, 77 met inclusion criteria for relevance to transitional care and appropriateness of population and setting. Of these, only 3 articles incorporated all required elements for TCM service. Although 2 were program improvement designs and none were randomized controlled studies, each report reduced readmission rates. Evidence for TCM effectiveness is limited. Additional study of TCM implementation and programmatic support for TCM is warranted.

  9. Updating the M Dwarf Planet Occurrence Rate by Injecting and Detecting Transits in Kepler Light Curves

    NASA Astrophysics Data System (ADS)

    Dressing, Courtney D.; Charbonneau, D.

    2014-01-01

    The primary goal of the Kepler mission is to constrain the occurrence rate of planets around stars with a range of spectral types. Previously, we estimated the M dwarf planet occurrence rate by revising the stellar parameters of the Kepler M dwarfs and analyzing the first six quarters of Kepler data. We found that there are 0.90 Earth-size (0.5-1.4 Earth radius) planets with periods <50 days per small star. We also found an occurrence rate of 0.15 Earth-size planets within the habitable zone per small star, implying a most probable distance of 13 pc to the nearest transiting potentially habitable planet. Our previous estimate of the occurrence rate assumed 100% detection efficiency at SNR=7.1 sigma, but the occurrence rate would have been underestimated if the actual detection efficiency is lower. In order to more accurately model the detection efficiency, we have developed a customized transit search pipeline tailored for application to M dwarfs. We measure the detection efficiency of our pipeline by injecting known transit signals into Kepler light curves and attempting to recover the signals. We are currently conducting a search for additional transiting planets using our pipeline and will compare our list of detected candidates to the candidates found by the Kepler team. We will then combine our more sophisticated model for the detection threshold and the list of planet candidates found using an additional ten quarters of Kepler data with our revised stellar parameters to present an updated measurement of the planet occurrence rate for M dwarfs. Our revised measurement will help enable predictions of the population of planets that will be detected by ongoing and future planet surveys such as MEarth and the Transiting Exoplanet Survey Satellite.

  10. Solidification and fcc to metastable hcp phase transition in krypton under variable compression rates

    NASA Astrophysics Data System (ADS)

    Chen, Jing-Yin; Yoo, Choong-Shik; Evans, William J.; Liermann, Hanns-Peter; Cynn, Hyunchae; Kim, Minseob; Jenei, Zsolt

    2014-10-01

    We present time-resolved synchrotron x-ray diffraction measurements to study kinetics associated with the liquid-solid and solid-solid high-pressure phase transitions in Kr under dynamic loading in a dynamic-diamond anvil cell. The results show a strong compression-rate dependence of the solidification/melting process in liquid Kr. The analysis of the compression-rate dependent melting/solidification, using an Avrami equation with the parameter n =1, indicates a spontaneous nucleation and one-dimensional growth mechanism. In contrast, the face-centered-cubic to metastable hexagonal close-packed transition in solid Kr occurs rapidly at ˜0.8 GPa near the melting line, which has negligible compression-rate dependence within the range of compression rates studied (0.004-13 GPa /s).

  11. A Peer-Led High School Transition Program Increases Graduation Rates among Latino Males

    ERIC Educational Resources Information Center

    Johnson, Valerie L.; Simon, Patricia; Mun, Eun-Young

    2014-01-01

    The authors investigated the impact of a manualized high school transition program, the Peer Group Connection (PGC) program, on the graduation rate at a low-income, Mid-Atlantic high school. The program utilized 12th-grade student peer leaders to create a supportive environment for incoming ninth-grade students. Results of a randomized control…

  12. False vacuum transitions —Analytical solutions and decay rate values

    NASA Astrophysics Data System (ADS)

    Correa, R. A. C.; Moraes, P. H. R. S.; da Rocha, Roldão

    2015-08-01

    In this work we show a class of oscillating configurations for the evolution of the domain walls in Euclidean space. The solutions are obtained analytically. Phase transitions are achieved from the associated fluctuation determinant, by the decay rates of the false vacuum.

  13. Accurate determination of predissociation rates and transition frequencies for carbon monoxide

    NASA Astrophysics Data System (ADS)

    Ubachs, W.; Eikema, K. S. E.; Levelt, P. F.; Hogervorst, W.; Drabbels, M.; Meerts, W. L.; Meulen, J. J. Ter

    1994-05-01

    By making use of two different laser spectroscopic techniques involving narrowband pulsed lasers in the visible, ultraviolet, and extreme-ultraviolet wavelength ranges, highly accurate data on absolute transition frequencies and predissociation rates were obtained for a number of excited stats of CO and its isotopes. These data are combined, reanalyzed, and presented here in concise form.

  14. A Peer-Led High School Transition Program Increases Graduation Rates among Latino Males

    ERIC Educational Resources Information Center

    Johnson, Valerie L.; Simon, Patricia; Mun, Eun-Young

    2014-01-01

    The authors investigated the impact of a manualized high school transition program, the Peer Group Connection (PGC) program, on the graduation rate at a low-income, Mid-Atlantic high school. The program utilized 12th-grade student peer leaders to create a supportive environment for incoming ninth-grade students. Results of a randomized control…

  15. A Comparison of Ego Identify Status Transition Pathways and Change Rates across Five Identity Domains.

    ERIC Educational Resources Information Center

    Kroger, Jane; Haslett, Stephen J.

    1991-01-01

    Examined whether ego identity status transition pathways and change rates differ significantly across domains of identity development from adolescence through middle adulthood. Interviews with 100 middle-aged adults regarding development of values in vocation, religion, politics, gender roles, and relationships identified 8 subgroups which varied…

  16. Nucleation kinetics and crystal growth with fluctuating rates at the intermediate stage of phase transitions

    NASA Astrophysics Data System (ADS)

    Alexandrov, D. V.; Malygin, A. P.

    2014-01-01

    Crystal growth kinetics accompanied by particle growth with fluctuating rates at the intermediate stage of phase transitions is analyzed theoretically. The integro-differential model of governing equations is solved analytically for size-independent growth rates and arbitrary dependences of the nucleation frequency on supercooling/supersaturation. Two important cases of Weber-Volmer-Frenkel-Zel'dovich and Mier nucleation kinetics are detailed. A Fokker-Plank type equation for the crystal-size density distribution function is solved explicitly.

  17. Effects of Proton Radiation Dose, Dose Rate and Dose Fractionation on Hematopoietic Cells in Mice

    PubMed Central

    Ware, J. H.; Sanzari, J.; Avery, S.; Sayers, C.; Krigsfeld, G.; Nuth, M.; Wan, X. S.; Rusek, A.; Kennedy, A. R.

    2012-01-01

    The present study evaluated the acute effects of radiation dose, dose rate and fractionation as well as the energy of protons in hematopoietic cells of irradiated mice. The mice were irradiated with a single dose of 51.24 MeV protons at a dose of 2 Gy and a dose rate of 0.05–0.07 Gy/min or 1 GeV protons at doses of 0.1, 0.2, 0.5, 1, 1.5 and 2 Gy delivered in a single dose at dose rates of 0.05 or 0.5 Gy/min or in five daily dose fractions at a dose rate of 0.05 Gy/min. Sham-irradiated animals were used as controls. The results demonstrate a dose-dependent loss of white blood cells (WBCs) and lymphocytes by up to 61% and 72%, respectively, in mice irradiated with protons at doses up to 2 Gy. The results also demonstrate that the dose rate, fractionation pattern and energy of the proton radiation did not have significant effects on WBC and lymphocyte counts in the irradiated animals. These results suggest that the acute effects of proton radiation on WBC and lymphocyte counts are determined mainly by the radiation dose, with very little contribution from the dose rate (over the range of dose rates evaluated), fractionation and energy of the protons. PMID:20726731

  18. Effects of proton radiation dose, dose rate and dose fractionation on hematopoietic cells in mice.

    PubMed

    Ware, J H; Sanzari, J; Avery, S; Sayers, C; Krigsfeld, G; Nuth, M; Wan, X S; Rusek, A; Kennedy, A R

    2010-09-01

    The present study evaluated the acute effects of radiation dose, dose rate and fractionation as well as the energy of protons in hematopoietic cells of irradiated mice. The mice were irradiated with a single dose of 51.24 MeV protons at a dose of 2 Gy and a dose rate of 0.05-0.07 Gy/min or 1 GeV protons at doses of 0.1, 0.2, 0.5, 1, 1.5 and 2 Gy delivered in a single dose at dose rates of 0.05 or 0.5 Gy/min or in five daily dose fractions at a dose rate of 0.05 Gy/min. Sham-irradiated animals were used as controls. The results demonstrate a dose-dependent loss of white blood cells (WBCs) and lymphocytes by up to 61% and 72%, respectively, in mice irradiated with protons at doses up to 2 Gy. The results also demonstrate that the dose rate, fractionation pattern and energy of the proton radiation did not have significant effects on WBC and lymphocyte counts in the irradiated animals. These results suggest that the acute effects of proton radiation on WBC and lymphocyte counts are determined mainly by the radiation dose, with very little contribution from the dose rate (over the range of dose rates evaluated), fractionation and energy of the protons.

  19. Effects of proton radiation dose, dose rate and dose fractionation on hematopoietic cells in mice

    SciTech Connect

    Ware, J.H.; Rusek, A.; Sanzari, J.; Avery, S.; Sayers, C.; Krigsfeld, G.; Nuth, M.; Wan, X.S.; Kennedy, A.R.

    2010-09-01

    The present study evaluated the acute effects of radiation dose, dose rate and fractionation as well as the energy of protons in hematopoietic cells of irradiated mice. The mice were irradiated with a single dose of 51.24 MeV protons at a dose of 2 Gy and a dose rate of 0.05-0.07 Gy/min or 1 GeV protons at doses of 0.1, 0.2, 0.5, 1, 1.5 and 2 Gy delivered in a single dose at dose rates of 0.05 or 0.5 Gy/min or in five daily dose fractions at a dose rate of 0.05 Gy/min. Sham-irradiated animals were used as controls. The results demonstrate a dose-dependent loss of white blood cells (WBCs) and lymphocytes by up to 61% and 72%, respectively, in mice irradiated with protons at doses up to 2 Gy. The results also demonstrate that the dose rate, fractionation pattern and energy of the proton radiation did not have significant effects on WBC and lymphocyte counts in the irradiated animals. These results suggest that the acute effects of proton radiation on WBC and lymphocyte counts are determined mainly by the radiation dose, with very little contribution from the dose rate (over the range of dose rates evaluated), fractionation and energy of the protons.

  20. Ambient dose and dose rate measurements in the vicinity of Elekta Precise accelerators for radiation therapy.

    PubMed

    Zutz, H; Hupe, O

    2014-12-01

    In radiation therapy, commercially available medical linear accelerators (LINACs) are used. At high primary beam energies in the 10-MeV range, the leakage dose of the accelerator head and the backscatter from the room walls, the air and the patient become more important. Therefore, radiation protection measurements of photon dose rates in the treatment room and in the maze are performed to quantify the radiation field. Since the radiation of the LINACs is usually pulsed with short radiation pulse durations in the microsecond range, there are problems with electronic dose (rate) meters commonly used in radiation protection. In this paper measurements with ionisation chambers are presented and electronic dosemeters are used for testing at selected positions. The measured time-averaged dose rate ranges from a few microsieverts per hour in the maze to some millisieverts per hour in the vicinity of the accelerator head and up to some sieverts per hour in the blanked primary beam and several hundred sieverts per hour in the direct primary beam.

  1. Impact of subgrid-scale radiative heating variability on the stratocumulus-to-trade cumulus transition in climate models

    SciTech Connect

    Xiao, Heng; Gustafson, William I.; Wang, Hailong

    2014-04-29

    Subgrid-scale interactions between turbulence and radiation are potentially important for accurately reproducing marine low clouds in climate models. To better understand the impact of these interactions, the Weather Research and Forecasting (WRF) model is configured for large eddy simulation (LES) to study the stratocumulus-to-trade cumulus (Sc-to-Cu) transition. Using the GEWEX Atmospheric System Studies (GASS) composite Lagrangian transition case and the Atlantic Trade Wind Experiment (ATEX) case, it is shown that the lack of subgrid-scale turbulence-radiation interaction, as is the case in current generation climate models, accelerates the Sc-to-Cu transition. Our analysis suggests that in cloud-topped boundary layers subgrid-scale turbulence-radiation interactions contribute to stronger production of temperature variance, which in turn leads to stronger buoyancy production of turbulent kinetic energy and helps to maintain the Sc cover.

  2. Energy exchange between a laser beam and charged particles using inverse transition radiation and method for its use

    DOEpatents

    Kimura, Wayne D.; Romea, Richard D.; Steinhauer, Loren C.

    1998-01-01

    A method and apparatus for exchanging energy between relativistic charged particles and laser radiation using inverse diffraction radiation or inverse transition radiation. The beam of laser light is directed onto a particle beam by means of two optical elements which have apertures or foils through which the particle beam passes. The two apertures or foils are spaced by a predetermined distance of separation and the angle of interaction between the laser beam and the particle beam is set at a specific angle. The separation and angle are a function of the wavelength of the laser light and the relativistic energy of the particle beam. In a diffraction embodiment, the interaction between the laser and particle beams is determined by the diffraction effect due to the apertures in the optical elements. In a transition embodiment, the interaction between the laser and particle beams is determined by the transition effect due to pieces of foil placed in the particle beam path.

  3. Sigh rate during emotional transitions: More evidence for a sigh of relief.

    PubMed

    Vlemincx, Elke; Meulders, Michel; Abelson, James L

    2017-04-01

    Evidence suggests that sighs regulate stress and emotions, e.g. by facilitating relief. This study aimed to investigate sigh rates during relief. In addition, links between sighs, anxiety sensitivity and HPA-axis activity were explored. Healthy volunteers (N=29) were presented cues predicting the valence of subsequent stimuli. By sequencing cues that predicted pleasant or unpleasant stimuli with or without certainty, transitions to certain pleasantness (relief) or to certain unpleasantness (control) were created and compared to no transitions. Salivary cortisol, anxiety sensitivity and respiration were measured. Sigh frequency was significantly higher during relief than during control transitions and no transition states, and higher during control transitions than during no transition states. Sigh frequency increased with steeper cortisol declines for high anxiety sensitive persons. Results confirm a relationship between sighs and relief. In addition, results suggest that sigh frequency is importantly related to HPA-axis activity, particularly in high anxiety sensitive persons. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Reconciling the Difference of Hot Jupiter Occurrence Rates From the Doppler and Transiting Planet Surveys

    NASA Astrophysics Data System (ADS)

    Wang, Ji; Fischer, Debra

    2015-08-01

    Many hot Jupiters (HJs) are detected by the Doppler and transit techniques. From surveys using these two techniques, however, the measured HJ occurrence rates differ by a factor of two or more. Using the California Planet Survey sample and the Kepler sample, we investigate the causes for this difference in the HJ occurrence rate. We find that 12.8% ± 0.24% of HJs are misidentified in the Kepler mission because of photometric dilution and subgiant contamination. We explore the differences between the Doppler sample and the Kepler sample that can account for the different HJ occurrence rate. We discuss how to measure the fundamental HJ occurrence rates by synthesizing the results from the Doppler and Kepler surveys. The fundamental HJ occurrence rates are measures of the HJ occurrence rate as a function of stellar multiplicity and evolutionary stage, e.g., the HJ occurrence rate for single and multiple stars or for main-sequence and subgiant stars.

  5. Results of a Direct Search Using Synchrotron Radiation for the Low-Energy (229)Th Nuclear Isomeric Transition.

    PubMed

    Jeet, Justin; Schneider, Christian; Sullivan, Scott T; Rellergert, Wade G; Mirzadeh, Saed; Cassanho, A; Jenssen, H P; Tkalya, Eugene V; Hudson, Eric R

    2015-06-26

    We report the results of a direct search for the (229)Th (I(π)=3/2(+)←5/2(+)) nuclear isomeric transition, performed by exposing (229)Th-doped LiSrAlF(6) crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1-2) s≲τ≲(2000-5600)  s. This measurement excludes roughly half of the favored transition search area and can be used to direct future searches.

  6. Results of a Direct Search Using Synchrotron Radiation for the Low-Energy Th229 Nuclear Isomeric Transition

    DOE PAGES

    Jeet, Justin; Schneider, Christian; Sullivan, Scott T.; ...

    2015-06-23

    We report the results of a direct search for the 229Tn (Iπ = 3/2+ ← 5/2+) nuclear isomeric transition, performed by exposing 229Tn-doped LiSrAlF6 crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1–2) s≲τ≲ (2000-5600) s. Lastly, this measurement excludes roughly half of the favored transition search area and can be used to direct future searches.

  7. Results of a Direct Search Using Synchrotron Radiation for the Low-Energy 229Th Nuclear Isomeric Transition

    NASA Astrophysics Data System (ADS)

    Jeet, Justin; Schneider, Christian; Sullivan, Scott T.; Rellergert, Wade G.; Mirzadeh, Saed; Cassanho, A.; Jenssen, H. P.; Tkalya, Eugene V.; Hudson, Eric R.

    2015-06-01

    We report the results of a direct search for the 229Th (Iπ=3 /2+←5 /2+ ) nuclear isomeric transition, performed by exposing 229Th -doped LiSrAlF6 crystals to tunable vacuum-ultraviolet synchrotron radiation and observing any resulting fluorescence. We also use existing nuclear physics data to establish a range of possible transition strengths for the isomeric transition. We find no evidence for the thorium nuclear transition between 7.3 eV and 8.8 eV with transition lifetime (1-2) s ≲τ ≲(2000 - 5600 ) s . This measurement excludes roughly half of the favored transition search area and can be used to direct future searches.

  8. Isodose mapping of terrestrial gamma radiation dose rate of Selangor state, Kuala Lumpur and Putrajaya, Malaysia.

    PubMed

    Sanusi, M S M; Ramli, A T; Gabdo, H T; Garba, N N; Heryanshah, A; Wagiran, H; Said, M N

    2014-09-01

    A terrestrial gamma radiation survey for the state of Selangor, Kuala Lumpur and Putrajaya was conducted to obtain baseline data for environmental radiological health practices. Based on soil type, geological background and information from airborne survey maps, 95 survey points statistically representing the study area were determined. The measured doses varied according to geological background and soil types. They ranged from 17 nGy h(-1) to 500 nGy h(-1). The mean terrestrial gamma dose rate in air above the ground was 182 ± 81 nGy h(-1). This is two times higher than the average dose rate of terrestrial gamma radiation in Malaysia which is 92 nGy h(-1) (UNSCEAR 2000). An isodose map was produced to represent exposure rate from natural sources of terrestrial gamma radiation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Multicomponent measurements of the Jefferson Lab energy recovery linac electron beam using optical transition and diffraction radiation

    NASA Astrophysics Data System (ADS)

    Holloway, M. A.; Fiorito, R. B.; Shkvarunets, A. G.; O'Shea, P. G.; Benson, S. V.; Douglas, D.; Evtushenko, P.; Jordan, K.

    2008-08-01

    High brightness electron accelerators, such as energy recovery linacs (ERL), often have complex particle distributions that can create difficulties in beam transport as well as matching to devices such as wigglers used to generate radiation from the beam. Optical transition radiation (OTR), OTR interferometry (OTRI), and optical diffraction-transition radiation interferometry (ODTRI) have proven to be effective tools for diagnosing both the spatial and angular distributions of charged particle beams. OTRI and ODTRI have been used to measure rms divergences, and optical transverse phase space mapping has been demonstrated using OTRI. In this work we present the results of diagnostic experiments using OTR and optical diffraction radiation conducted at the Jefferson Laboratory’s 115 MeV ERL which show the presence of two separate components within the beam’s spatial and angular distributions. By assuming a correlation between the spatial and angular features, we estimate an rms emittance value for each of the two components.

  10. Theoretical estimation of the radiative cooling rate in the Jovian troposphere

    NASA Astrophysics Data System (ADS)

    Takahashi, Yasuto; Hashimoto, George L.; Ishiwatari, Masaki; Takahashi, Yoshiyuki O.; Sugiyama, Ko-ichiro; Onishi, Masanori; Kuramoto, Kiyoshi

    2015-11-01

    Jupiter exhibits characteristic cloud activities but their physical mechanism remains poorly understood. Recently, Sugiyama et al. (2014) demonstrated that the Jovian cloud convection may have a significant intermittency in the generation of cumulonimbus clouds with the typical interval length controlled by the radiative cooling rate in the upper troposphere. In spite of such importance as a controlling factor of cloud activity, the tropospheric radiative cooling rate profile has never been systematically quantified for the Jovian system. In the Jovian troposphere, condensable species (NH3, H2S, H2O) and their condensates might significantly contribute to radiative transfer.Here we show numerical estimates of radiative cooling rate profile under Jovian troposphere condition by using our non-gray radiative transfer model that contains optical properties of gas species (H2, He, H2O, CH4, NH3, H2S, and PH3) and cloud layers made of H2O, NH4SH, and NH3 ice particles. The temperature profile is determined by the radiative-convective equilibrium state satisfying an observed potential temperature of Jovian troposphere. The mean vertical distributions of gas and cloud are given on the basis of the latest hydrodynamic simulation of Jovian cloud convection (Sugiyama et al., 2014) and cosmochemical consideration.The modeled atmosphere has the tropopause at ~0.38 bar level. The radiative cooling rate reaches the maximum 15 x 10-3 K/Jovian day at ~0.5 bar level, then decreases with depth and approaches zero below 5 bar level. This profile is largely determined by the thermal absorption and emission due to gaseous NH3 and H2 with a slight modification by solar heating due to CH4. The cloud layers are found to have only a weak effect on either radiative cooling or heating because their opacities in the longwave radiation are estimated to be very small, which agrees with the observed 5-micron spectrum with high brightness temperatures. The uncertainty in H2O abundance in deep

  11. The phase transition in VO2 probed using x-ray, visible and infrared radiations

    SciTech Connect

    Kumar, Suhas; Strachan, John Paul; Kilcoyne, A. L. David; Tyliszczak, Tolek; Pickett, Matthew D.; Santori, Charles; Gibson, Gary; Williams, R. Stanley

    2016-02-15

    Vanadium dioxide (VO2) is a model system that has been used to understand closely occurring multiband electronic (Mott) and structural (Peierls) transitions for over half a century due to continued scientific and technological interests. Among the many techniques used to study VO2, the most frequently used involve electromagnetic radiation as a probe. Understanding of the distinct physical information provided by different probing radiations is incomplete, mostly owing to the complicated nature of the phase transitions. Here, we use transmission of spatially averaged infrared (λ = 1.5 μm) and visible (λ = 500 nm) radiations followed by spectroscopy and nanoscale imaging using x-rays (λ = 2.25–2.38 nm) to probe the same VO2 sample while controlling the ambient temperature across its hysteretic phase transitions and monitoring its electrical resistance. We directly observed nanoscale puddles of distinct electronic and structural compositions during the transition. The two main results are that, during both heating and cooling, the transition of infrared and visible transmission occurs at significantly lower temperatures than the Mott transition, and the electronic (Mott) transition occurs before the structural (Peierls) transition in temperature. We use our data to provide insights into possible microphysical origins of the different transition characteristics. We highlight that it is important to understand these effects because small changes in the nature of the probe can yield quantitatively, and even qualitatively, different results when applied to a non-trivial multiband phase transition. Our results guide more judicious use of probe type and interpretation of the resulting data.

  12. Transitions.

    ERIC Educational Resources Information Center

    Agnew, Jeanne L.; Choike, James R.

    1987-01-01

    Mathematical observations are made about some continuous curves, called transitions, encountered in well-known experiences. The transition parabola, the transition spiral, and the sidestep maneuver are presented. (MNS)

  13. Configuration splitting and gamma-decay transition rates in the two-group shell model

    SciTech Connect

    Isakov, V. I.

    2015-09-15

    Expressions for reduced gamma-decay transition rates were obtained on the basis of the twogroup configuration model for the case of transitions between particles belonging to identical groups of nucleons. In practical applications, the present treatment is the most appropriate for describing decays for odd–odd nuclei in the vicinity of magic nuclei or for nuclei where the corresponding subshells stand out in energy. Also, a simple approximation is applicable to describing configuration splitting in those cases. The present calculations were performed for nuclei whose mass numbers are close to A ∼ 90, including N = 51 odd—odd isotones.

  14. Strain rate-induced phase transitions in an impact-hardening polymer composite

    NASA Astrophysics Data System (ADS)

    Jiang, Weifeng; Gong, Xinglong; Wang, Sheng; Chen, Qian; Zhou, Hong; Jiang, Wanquan; Xuan, Shouhu

    2014-03-01

    An impact-hardening polymer composite that is promising as a protective equipment material for its excellent performance and comfortable characteristics is shown. Falling weight impact experiments are performed to characterize its protective behavior, which is realized by absorbing energy and resisting deformation. From the mechanical tests in different strain rate, it is seen to undergo transitions from a viscous-liquid behavior to a rubbery behavior, then to a glassy behavior. These phase transition are found to be essential for their practical applications in the energy absorption and the deformation resistance.

  15. Pretreatment Growth Rate Predicts Radiation Response in Vestibular Schwannomas

    SciTech Connect

    Niu, Nina N.; Niemierko, Andrzej; Larvie, Mykol; Curtin, Hugh; Loeffler, Jay S.; McKenna, Michael J.; Shih, Helen A.

    2014-05-01

    Purpose: Vestibular schwannomas (VS) are often followed without initial therapeutic intervention because many tumors do not grow and radiation therapy is associated with potential adverse effects. In an effort to determine whether maximizing initial surveillance predicts for later treatment response, the predictive value of preirradiation growth rate of VS on response to radiation therapy was assessed. Methods and Materials: Sixty-four patients with 65 VS were treated with single-fraction stereotactic radiation surgery or fractionated stereotactic radiation therapy. Pre- and postirradiation linear expansion rates were estimated using volumetric measurements on sequential magnetic resonance images (MRIs). In addition, postirradiation tumor volume change was classified as demonstrating shrinkage (ratio of volume on last follow-up MRI to MRI immediately preceding irradiation <80%), stability (ratio 80%-120%), or expansion (ratio >120%). The median pre- and postirradiation follow-up was 20.0 and 27.5 months, respectively. Seven tumors from neurofibromatosis type 2 (NF2) patients were excluded from statistical analyses. Results: In the 58 non-NF2 patients, there was a trend of correlation between pre- and postirradiation volume change rates (slope on linear regression, 0.29; P=.06). Tumors demonstrating postirradiation expansion had a median preirradiation growth rate of 89%/year, and those without postirradiation expansion had a median preirradiation growth rate of 41%/year (P=.02). As the preirradiation growth rate increased, the probability of postirradiation expansion also increased. Overall, 24.1% of tumors were stable, 53.4% experienced shrinkage, and 22.5% experienced expansion. Predictors of no postirradiation tumor expansion included no prior surgery (P=.01) and slower tumor growth rate (P=.02). The control of tumors in NF2 patients was only 43%. Conclusions: Radiation therapy is an effective treatment for VS, but tumors that grow quickly preirradiation may be

  16. Electron transfer by excited benzoquinone anions: slow rates for two-electron transitions.

    PubMed

    Zamadar, Matibur; Cook, Andrew R; Lewandowska-Andralojc, Anna; Holroyd, Richard; Jiang, Yan; Bikalis, Jin; Miller, John R

    2013-09-05

    Electron transfer (ET) rate constants from the lowest excited state of the radical anion of benzoquinone, BQ(-•)*, were measured in THF solution. Rate constants for bimolecular electron transfer reactions typically reach the diffusion-controlled limit when the free-energy change, ΔG°, reaches -0.3 eV. The rate constants for ET from BQ(-•)* are one-to-two decades smaller at this energy and do not reach the diffusion-controlled limit until -ΔG° is 1.5-2.0 eV. The rates are so slow probably because a second electron must also undergo a transition to make use of the energy of the excited state. Similarly, ET, from solvated electrons to neutral BQ to form the lowest excited state, is slow, while fast ET is observed at a higher excited state, which can be populated in a transition involving only one electron. A simple picture based on perturbation theory can roughly account for the control of electron transfer by the need for transition of a second electron. The picture also explains how extra driving force (-ΔG°) can restore fast rates of electron transfer.

  17. Distribution of terrestrial gamma radiation dose rate in the eastern coastal area of Odisha, India.

    PubMed

    Gusain, G S; Rautela, B S; Sahoo, S K; Ishikawa, T; Prasad, G; Omori, Y; Sorimachi, A; Tokonami, S; Ramola, R C

    2012-11-01

    Terrestrial gamma radiation is one of the important radiation exposures on the earth's surface that results from the three primordial radionuclides (226)Ra, (232)Th and (40)K. The elemental concentration of these elements in the earth's crust could result in the anomalous variation of the terrestrial gamma radiation in the environment. The geology of the local area plays an important role in distribution of these radioactive elements. Environmental terrestrial gamma radiation dose rates were measured around the eastern coastal area of Odisha with the objective of establishing baseline data on the background radiation level. The values of the terrestrial gamma radiation dose rate vary significantly at different locations in the study area. The values of the terrestrial gamma dose rate ranged from 77 to 1651 nGy h(-1), with an average of 230 nGy h(-1). During the measurement of the terrestrial gamma dose rate, sand and soil samples were also collected for the assessment of natural radionuclides. The activities of (226)Ra, (232)Th and (40)K from these samples were measured using a gamma-ray spectrometry with a NaI(Tl) detector. Activity concentrations of (226)Ra, (232)Th and (40)K ranged from 15.6 to 69 Bq kg(-1) with an average of 46.7 Bq kg(-1), from 28.9 to 973 Bq kg(-1) with an average of 250 Bq kg(-1) and from 139 to 952 Bq kg(-1) with an average of 429, respectively. The detailed significance of these studies has been discussed from the radiation protection point of view.

  18. Experimental study of radiation dose rate at different strategic points of the BAEC TRIGA Research Reactor.

    PubMed

    Ajijul Hoq, M; Malek Soner, M A; Salam, M A; Haque, M M; Khanom, Salma; Fahad, S M

    2017-09-09

    The 3MW TRIGA Mark-II Research Reactor of Bangladesh Atomic Energy Commission (BAEC) has been under operation for about thirty years since its commissioning at 1986. In accordance with the demand of fundamental nuclear research works, the reactor has to operate at different power levels by utilizing a number of experimental facilities. Regarding the enquiry for safety of reactor operating personnel and radiation workers, it is necessary to know the radiation level at different strategic points of the reactor where they are often worked. In the present study, neutron, beta and gamma radiation dose rate at different strategic points of the reactor facility with reactor power level of 2.4MW was measured to estimate the rising level of radiation due to its operational activities. From the obtained results high radiation dose is observed at the measurement position of the piercing beam port which is caused by neutron leakage and accordingly, dose rate at the stated position with different reactor power levels was measured. This study also deals with the gamma dose rate measurements at a fixed position of the reactor pool top surface for different reactor power levels under both Natural Convection Cooling Mode (NCCM) and Forced Convection Cooling Mode (FCCM). Results show that, radiation dose rate is higher for NCCM in compared with FCCM and increasing with the increase of reactor power. Thus, concerning the radiological safety issues for working personnel and the general public, the radiation dose level monitoring and the experimental analysis performed within this paper is so much effective and the result of this work can be utilized for base line data and code verification of the nuclear reactor. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Further time-resolved electron-beam characterizations with optical transition radiation

    SciTech Connect

    Lumpkin, A.H. . Advanced Photon Source Accelerator Systems Div.); Wilke, M.D. )

    1992-01-01

    Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 [mu]s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatialposition and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kick effects are reported as a function of charge.

  20. Time-resolved electron-beam characterizations with optical transition radiation

    SciTech Connect

    Lumpkin, A.H. ); Wilke, M.D. )

    1992-01-01

    Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 {mu}s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatial position and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kicks are reported as a function of charge.

  1. Time-resolved electron-beam characterizations with optical transition radiation

    SciTech Connect

    Lumpkin, A.H.; Wilke, M.D.

    1992-09-01

    Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 {mu}s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatial position and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kicks are reported as a function of charge.

  2. Further time-resolved electron-beam characterizations with optical transition radiation

    SciTech Connect

    Lumpkin, A.H.; Wilke, M.D.

    1992-12-31

    Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 {mu}s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatialposition and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kick effects are reported as a function of charge.

  3. Radiative quantum efficiency in an InAs/AlSb intersubband transition

    NASA Astrophysics Data System (ADS)

    Faugeras, C.; Wade, A.; Leuliet, A.; Vasanelli, A.; Sirtori, C.; Fedorov, G.; Smirnov, D.; Teissier, R.; Baranov, A. N.; Barate, D.; Devenson, J.

    2006-09-01

    The quantum efficiency of an electroluminescent intersubband emitter based on InAs/AlSb has been measured as a function of the magnetic field up to 20T . Two series of oscillations periodic in 1/B are observed, corresponding to the elastic and inelastic scattering of electrons of the upper state of the radiative transitions. Experimental results are accurately reproduced by a calculation of the excited-state lifetime as a function of the applied magnetic field. The interpretation of these data gives an exact measure of the relative weight of the scattering mechanisms and allows the extraction of material parameters such as the energy-dependent electron effective mass and the optical phonon energy.

  4. The phenomenological status of late time phase transition models after cosmic background radiation anisotropy measurements

    NASA Technical Reports Server (NTRS)

    Luo, Xiaochun; Schramm, David N.

    1994-01-01

    Some relatively model-independent results for structure formation via late time phase transitions (LTPT) are discussed. In particular, generic LTPT power spectra are presented. The implication of the recent Cosmic Background Explorer (COBE) detection of the cosmic background radiation (CBR) anisotropy at large angular scales (greater than or approximately equal to 7 deg) and the tight upper limits from small angular scales (approximately 1 deg) to LTPT models are discussed. Special attention is focused on the observational constraints and possible non-Gaussian signatures of CBR temperature anisotropies from LTPT and other non-Gaussian models. It is shown that while LTPT have been seriously constrained by the recent data, viable models do remain which provide more power on the 100-200 Mpc scales than do more traditional primordial Gaussian density fluctuation models. Tests for such models are presented, including possible anisotropies on angular scales less than 8 min.

  5. A novel coaxial Ku-band transit radiation oscillator without external guiding magnetic field

    NASA Astrophysics Data System (ADS)

    Ling, Junpu; Zhang, Jiande; He, Juntao; Jiang, Tao

    2014-02-01

    A novel coaxial transit radiation oscillator without external guiding magnetic field is designed to generate high power microwave at Ku-band. By using a coaxial structure, the space-charge potential energy is suppressed significantly, that is good for enhancing efficient beam-wave interaction. In order to improve the transmission stability of the unmagnetized intense relativistic electron beam, a Pierce-like cathode is employed in the novel device. By contrast with conventional relativistic microwave generators, this kind of device has the advantages of high stability, non-guiding magnetic field, and high efficiency. Moreover, with the coaxial design, it is possible to improve the power-handing capacity by increasing the radial dimension of the Ku-band device. With a 550 keV and 7.5 kA electron beam, a 1.25 GW microwave pulse at 12.08 GHz has been obtained in the simulation. The power conversion efficiency is about 30%.

  6. Time-Resolved Emittance Characterization of an Induction Linac Beam using Optical Transition Radiation

    SciTech Connect

    Le Sage, G P

    2002-11-05

    An induction linac is used by Lawrence Livermore National Laboratory to perform radiographic testing at the Flash X-ray Radiography facility. Emittance characterization is important since x-ray spot size impacts the resolution of shadow-graphs. Due to the long pulse length, high current, and beam energy, emittance measurement using Optical Transition Radiation is an attractive alternative for reasons that will be described in the text. The utility of OTR-based emittance measurement has been well demonstrated for both RF and induction linacs. We describe the time-resolved emittance characterization of an induction linac electron beam. We have refined the optical collection system for the induction linac application, and have demonstrated a new technique for probing the divergence of a subset of the beam profile. The experimental apparatus, data reduction, and conclusions will be presented. Additionally, a new scheme for characterizing the correlation between beam divergence and spatial coordinates within the beam profile will be described.

  7. Emittance Measurements of the Jefferson Lab Free Electron Laser using optical transition radiation

    SciTech Connect

    Holloway, Michael Andrew

    2007-05-01

    Charged particle accelerators, such as the ones that power Free Electron Lasers (FEL), require high quality (low emittance) beams for efficient operation. Accurate and reliable beam diagnostics are essential to monitoring beam parameters in order to maintain a high quality beam. Optical Transition Radiation Interferometry (OTRI) has shown potential to be a quality diagnostic that is especially useful for high brightness electron beams such as Jefferson Labs FEL energy recovery linac. The purpose of this project is to further develop OTRI beam diagnostic techniques. An optical system was designed to make beam size and divergence measurements as well as to prepare for experiments in optical phase space mapping. Beam size and beam divergence measurements were taken to calculate the emittance of the Jefferson Lab FEL. OTRI is also used to separate core and halo beam divergences in order to estimate core and halo emittance separately.

  8. Performance of the ATLAS Transition Radiation Tracker in Run 1 of the LHC: tracker properties

    DOE PAGES

    Aaboud, M.; Aad, G.; Abbott, B.; ...

    2017-05-03

    The tracking performance parameters of the ATLAS Transition Radiation Tracker (TRT) as part of the ATLAS inner detector are described in this paper for different data-taking conditions in proton-proton, proton-lead and lead-lead collisions at the Large Hadron Collider (LHC). The performance is studied using data collected during the first period of LHC operation (Run 1) and is compared with Monte Carlo simulations. The performance of the TRT, operating with two different gas mixtures (xenon-based and argon-based) and its dependence on the TRT occupancy is presented. Furthermore, these studies show that the tracking performance of the TRT is similar for themore » two gas mixtures and that a significant contribution to the particle momentum resolution is made by the TRT up to high particle densities.« less

  9. Performance of the ATLAS Transition Radiation Tracker in Run 1 of the LHC: tracker properties

    NASA Astrophysics Data System (ADS)

    Aaboud, M.; Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Abeloos, B.; Abidi, S. H.; AbouZeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adachi, S.; Adamczyk, L.; Adams, D. L.; Adelman, J.; Adersberger, M.; Adye, T.; Affolder, A. A.; Agatonovic-Jovin, T.; Agheorghiesei, C.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akatsuka, S.; Akerstedt, H.; Åkesson, T. P. A.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Ali, B.; Aliev, M.; Alimonti, G.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allen, B. W.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Alshehri, A. A.; Alstaty, M.; Alvarez Gonzalez, B.; Álvarez Piqueras, D.; Alviggi, M. G.; Amadio, B. T.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, J. K.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Angelidakis, S.; Angelozzi, I.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antel, C.; Antonelli, M.; Antonov, A.; Antrim, D. J.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Arabidze, G.; Arai, Y.; Araque, J. P.; Araujo Ferraz, V.; Arce, A. T. H.; Ardell, R. E.; Arduh, F. A.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Armitage, L. J.; Arnaez, O.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Artz, S.; Asai, S.; Asbah, N.; Ashkenazi, A.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Augsten, K.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baas, A. E.; Baca, M. J.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagiacchi, P.; Bagnaia, P.; Baines, J. T.; Bajic, M.; Baker, O. K.; Baldin, E. M.; Balek, P.; Balestri, T.; Balli, F.; Balunas, W. K.; Banas, E.; Banerjee, Sw.; Bannoura, A. A. E.; Barak, L.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisits, M.-S.; Barklow, T.; Barlow, N.; Barnes, S. L.; Barnett, B. M.; Barnett, R. M.; Barnovska-Blenessy, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barranco Navarro, L.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartos, P.; Basalaev, A.; Bassalat, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, M.; Bauer, F.; Bawa, H. S.; Beacham, J. B.; Beattie, M. D.; Beau, T.; Beauchemin, P. H.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, M.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bedognetti, M.; Bee, C. P.; Beermann, T. A.; Begalli, M.; Begel, M.; Behr, J. K.; Bell, A. S.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Belyaev, N. L.; Benary, O.; Benchekroun, D.; Bender, M.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez, J.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Beringer, J.; Berlendis, S.; Bernard, N. R.; Bernardi, G.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertoli, G.; Bertolucci, F.; Bertram, I. A.; Bertsche, C.; Bertsche, D.; Besjes, G. J.; Bessidskaia Bylund, O.; Bessner, M.; Besson, N.; Betancourt, C.; Bethani, A.; Bethke, S.; Bevan, A. J.; Bianchi, R. M.; Bianco, M.; Biebel, O.; Biedermann, D.; Bielski, R.; Biesuz, N. V.; Biglietti, M.; Bilbao De Mendizabal, J.; Billoud, T. R. V.; Bilokon, H.; Bindi, M.; Bingul, A.; Bini, C.; Biondi, S.; Bisanz, T.; Bittrich, C.; Bjergaard, D. M.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blazek, T.; Bloch, I.; Blocker, C.; Blue, A.; Blum, W.; Blumenschein, U.; Blunier, S.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Boerner, D.; Bogavac, D.; Bogdanchikov, A. G.; Bohm, C.; Boisvert, V.; Bokan, P.; Bold, T.; Boldyrev, A. S.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Bortfeldt, J.; Bortoletto, D.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Bossio Sola, J. D.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Boutle, S. K.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bracinik, J.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Breaden Madden, W. D.; Brendlinger, K.; Brennan, A. J.; Brenner, L.; Brenner, R.; Bressler, S.; Briglin, D. L.; Bristow, T. M.; Britton, D.; Britzger, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Broughton, J. H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruni, A.; Bruni, G.; Bruni, L. S.; Brunt, BH; Bruschi, M.; Bruscino, N.; Bryant, P.; Bryngemark, L.; Buanes, T.; Buat, Q.; Buchholz, P.; Buckley, A. G.; Budagov, I. A.; Buehrer, F.; Bugge, M. K.; Bulekov, O.; Bullock, D.; Burckhart, H.; Burdin, S.; Burgard, C. D.; Burger, A. M.; Burghgrave, B.; Burka, K.; Burke, S.; Burmeister, I.; Burr, J. T. P.; Busato, E.; Büscher, D.; Büscher, V.; Bussey, P.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Buzykaev, A. R.; Cabrera Urbán, S.; Caforio, D.; Cairo, V. M.; Cakir, O.; Calace, N.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Callea, G.; Caloba, L. P.; Calvente Lopez, S.; Calvet, D.; Calvet, S.; Calvet, T. P.; Camacho Toro, R.; Camarda, S.; Camarri, P.; Cameron, D.; Caminal Armadans, R.; Camincher, C.; Campana, S.; Campanelli, M.; Camplani, A.; Campoverde, A.; Canale, V.; Cano Bret, M.; Cantero, J.; Cao, T.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Carbone, R. M.; Cardarelli, R.; Cardillo, F.; Carli, I.; Carli, T.; Carlino, G.; Carlson, B. T.; Carminati, L.; Carney, R. M. D.; Caron, S.; Carquin, E.; Carrillo-Montoya, G. D.; Carvalho, J.; Casadei, D.; Casado, M. P.; Casolino, M.; Casper, D. W.; Castelijn, R.; Castelli, A.; Castillo Gimenez, V.; Castro, N. F.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Caudron, J.; Cavaliere, V.; Cavallaro, E.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Celebi, E.; Ceradini, F.; Cerda Alberich, L.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cervelli, A.; Cetin, S. A.; Chafaq, A.; Chakraborty, D.; Chan, S. K.; Chan, W. S.; Chan, Y. L.; Chang, P.; Chapman, J. D.; Charlton, D. G.; Chatterjee, A.; Chau, C. C.; Chavez Barajas, C. A.; Che, S.; Cheatham, S.; Chegwidden, A.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, S.; Chen, S.; Chen, X.; Chen, Y.; Cheng, H. C.; Cheng, H. 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G.; Vasquez, G. A.; Vazeille, F.; Vazquez Schroeder, T.; Veatch, J.; Veeraraghavan, V.; Veloce, L. M.; Veloso, F.; Veneziano, S.; Ventura, A.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vetterli, M. C.; Viaux Maira, N.; Viazlo, O.; Vichou, I.; Vickey, T.; Boeriu, O. E. Vickey; Viehhauser, G. H. A.; Viel, S.; Vigani, L.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vishwakarma, A.; Vittori, C.; Vivarelli, I.; Vlachos, S.; Vlasak, M.; Vogel, M.; Vokac, P.; Volpi, G.; Volpi, M.; von der Schmitt, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Wagner, P.; Wagner, W.; Wahlberg, H.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wallangen, V.; Wang, C.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, Q.; Wang, R.; Wang, S. M.; Wang, T.; Wang, W.; Wang, W.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Washbrook, A.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, A. F.; Webb, S.; Weber, M. S.; Weber, S. W.; Weber, S. A.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M. D.; Werner, P.; Wessels, M.; Whalen, K.; Whallon, N. L.; Wharton, A. M.; White, A.; White, M. J.; White, R.; Whiteson, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilk, F.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, J. A.; Wingerter-Seez, I.; Winklmeier, F.; Winston, O. J.; Winter, B. T.; Wittgen, M.; Wobisch, M.; Wolf, T. M. H.; Wolff, R.; Wolter, M. W.; Wolters, H.; Worm, S. D.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wozniak, K. W.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xi, Z.; Xia, L.; Xu, D.; Xu, L.; Yabsley, B.; Yacoob, S.; Yamaguchi, D.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yang, Z.; Yao, W.-M.; Yap, Y. C.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yildirim, E.; Yorita, K.; Yoshihara, K.; Young, C.; Young, C. J. S.; Youssef, S.; Yu, D. R.; Yu, J.; Yu, J.; Yuan, L.; Yuen, S. P. Y.; Yusuff, I.; Zabinski, B.; Zacharis, G.; Zaidan, R.; Zaitsev, A. M.; Zakharchuk, N.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanzi, D.; Zeitnitz, C.; Zeman, M.; Zemla, A.; Zeng, J. C.; Zeng, Q.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, F.; Zhang, G.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, L.; Zhang, M.; Zhang, R.; Zhang, R.; Zhang, X.; Zhang, Y.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhong, J.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, M.; Zhou, M.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; Zou, R.; zur Nedden, M.; Zwalinski, L.

    2017-05-01

    The tracking performance parameters of the ATLAS Transition Radiation Tracker (TRT) as part of the ATLAS inner detector are described in this paper for different data-taking conditions in proton-proton, proton-lead and lead-lead collisions at the Large Hadron Collider (LHC). The performance is studied using data collected during the first period of LHC operation (Run 1) and is compared with Monte Carlo simulations. The performance of the TRT, operating with two different gas mixtures (xenon-based and argon-based) and its dependence on the TRT occupancy is presented. These studies show that the tracking performance of the TRT is similar for the two gas mixtures and that a significant contribution to the particle momentum resolution is made by the TRT up to high particle densities.

  10. Very high resolution optical transition radiation imaging system: Comparison between simulation and experiment

    NASA Astrophysics Data System (ADS)

    Bolzon, B.; Aryshev, A.; Aumeyr, T.; Boogert, S.; Karataev, P.; Kruchinin, K. O.; Lefevre, T.; Mazzoni, S.; Nevay, L.; Shevelev, M.; Terunuma, N.; Urakawa, J.; Welsch, C. P.

    2015-08-01

    Optical transition radiation (OTR) has become a commonly used method for 2D beam imaging measurements. In the Accelerator Test Facility 2 (ATF2) at KEK, beam sizes smaller than the OTR point spread function have been measured. Simulations of the OTR imaging system have been performed using the ZEMAX software to study the effects of optical errors such as aberrations, diffraction, and misalignments of optical components. This paper presents a comparison of simulations of the OTR point spread function with experimental data obtained at ATF2. It shows how the quantification and control of optical errors impacts on optimizing the resolution of the system. We also show that the OTR point spread function needs to be predicted accurately to optimize any optical system and to predict the error made on measurement.

  11. Emittance and Energy Measurements of Low-Energy Electron Beam Using Optical Transition Radiation Techniques

    NASA Astrophysics Data System (ADS)

    Sakamoto, Fumito; Iijima, Hokuto; Dobashi, Katsuhiro; Imai, Takayuki; Ueda, Toru; Watanabe, Takahiro; Uesaka, Mitsuru

    2005-03-01

    Emittance and energy of an electron beam in the range of 8 to 22 MeV were measured via optical transition radiation (OTR) techniques. The beam divergence effect on observations of the far-field OTR image at low energies was studied by means of numerical analysis. The numerical analysis indicates that if the beam divergence is under 1.5 mrad, a simultaneous single-shot measurement of emittance and energy is possible. The results of the single-shot experiment agree with independent measurements conducted using the quadrupole scan method and an electron spectrometer. The experiments were performed with an S-band linac at the Nuclear Engineering Research Laboratory, The University of Tokyo (UTNL).

  12. Evidence for anomalous optical transition radiation linear polarization effects in beam-profile monitors

    NASA Astrophysics Data System (ADS)

    Lumpkin, A. H.; Johnson, A. S.; Ruan, J.; Thurman-Keup, R. M.; Yao, C.-Y.; Evtushenko, P.

    2013-10-01

    Investigations of the effects of optical transition radiation (OTR) polarization components on beam profiles are presented. The transverse profiles are examined using the OTR perpendicular and parallel polarization components with respect to the dimension of interest. We observed ˜15% projected profile size reductions with the perpendicularly polarized components on a 65-μm beam image size case at 14 MeV, a 150-μm beam image size at 4.5 GeV, and a 1100-μm beam image size at 7 GeV. These effects are all several times larger than expected (and anomalous in this sense) when compared to the standard OTR point-spread function calculations. We propose the time-averaged induced-current distribution which generates the OTR represents the actual beam size more faithfully with the perpendicular polarization component and recommend its routine use and subsequent deconvolution.

  13. Energy cross-calibration from the first CREAM flight : transition radiation detector versus calorimeter

    NASA Astrophysics Data System (ADS)

    Maestro, P.; Ahn, H.S.; Allison, P.S.; Bagliesi, M.G.; Beatty, J.J.; Bigongiari, G.; Boyle, P.J.; Brandt, T.J.; Childers, J.T.; Conklin, N.B.; Coutu, S.; DuVernois, M.A.; Ganel, O.; Han, J.H.; Hyun, H.J.; Jeon, J.A.; Kim, K.C.; Lee, J.K.; Lee, M.H.; Lutz, L.; Marrocchesi, P.S.; Malinine, A.; Minnick, S.; Mognet, S.I.; Nam, S.; Nutter, S.; Park, H.; Park, I.H.; Park, N.H.; Seo, E.S.; Sina, R.; Swordy, S.; Wakely, S.P.; Wu, J.; Yang, J.; Yoon, Y.S.; Zei, R.; Zinn, S.Y.

    The Cosmic Ray Energetics and Mass (CREAM) balloon experiment had two successful flights in 2004/05 and 2005/06. It was designed to perform energy measurements from a few GeV up to 1000 TeV, taking advantage of different detection techniques. The first instrument, CREAM-I, combined a transition radiation detector (equipped with an array of proportional tubes and an acrylic Cherenkov device) with a calorimeter to provide independent energy measurements of cosmic ray nuclei. Each detector was calibrated with particle beams in a limited range of energies. In order to assess the absolute energy scale of the whole instrument and to investigate the systematic effects of each technique, a cross-calibration was performed by comparing the independent energy estimates on selected samples of Oxygen and Carbon nuclei.

  14. Preliminary Experimental Studies of IFEL Micro-bunching by Coherent Transition Radiation

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Cline, D. B.; Wang, X. J.; Babzien, M.; Fang, J. M.; Kusche, K. P.

    1997-05-01

    An inverse free electron laser(IFEL) accelerator has been successfully operated at Brookhaven Accelerator Test Facility (ATF). One of the applications of IFEL accelerator is to produce micro-bunched beam for other laser accelerators because of the strong interaction between the CO2 laser and electron beam without distortion of electron beam quality due to the presence of plasma or other medium. A micro-bunching diagnostic system was built for detecting micro-bunching effects (10-fs bunch length) produced by the Inverse Free Electron Laser (IFEL) acceleration. The micro-bunched electron beam has been studied through measuring the coherent transition radiation (CTR) spectrum. The preliminary results indicate the first observation of micro-bunching from the IFEL acceleration.

  15. Dielectronic recombination rates, ionization equilibrium, and radiative emission rates for Mn ions in low-density high-temperature plasmas

    NASA Technical Reports Server (NTRS)

    Jacobs, V. L.; Davis, J.

    1983-01-01

    The analysis of optically-thin far-ultraviolet and X-ray emission lines of multiply-charged ions is one of the basic methods for determining the temperatures and densities of laboratory and astrophysical plasmas. In addition, the energy balance in these plasmas can be significantly influenced by the emission of radiation from relatively low concentrations of multiple-charged atomic ions. Because the populations of the excited levels are expected to depart substantially from their local thermodynamic equilibrium values a detailed treatment of the elementary collisional and radiative processes must be employed in order to predict the emission line intensities. In this investigation the authors present the results of calculations based on a corona equilibrium model in which a detailed evaluation is made of the dielectronic recombination rate coefficients. The ionization and autoionization following inner-shell electron excitation from each ground state are balanced by direct radiative and dielectronic recombination. The spectral line intensities emitted by the low-lying excited states, which are assumed to undergo spontaneous radiative decay in times that are short compared with the collision time, are evaluated in terms of the corona ionization equilibrium distributions of the ground states and their electron-impact excitation states.

  16. Calculation of Radiative Transition Energies and Probabilities of Highly Charged Ions: Applications to Xenon

    NASA Astrophysics Data System (ADS)

    Tanaka, Tsukiyo

    1995-01-01

    In this work, we have obtained new insight to the physical processes above and below a surface when an incident highly charged heavy ion interacts with a metal. Extensive theoretical calculations and predictions based on many body perturbation theory in conjunction with a screening theory were performed for the Xe^ {q+} (q = 44-49) ions interacting with copper surfaces and for the Bi^ {q+} (q = 71 to 50) ions interacting with gold surfaces. A detailed comparison of our theoretical results with experimental x-ray data provided by the EBIT facility at LLNL is presented. Specifically, in the theoretical calculations, many body perturbation theory is applied using a hydrogenic basis set to calculate numerous radiative transition energies and probabilities of various highly charged Bi and Xe ions for a large number of initial and final configurations. The application of perturbation theory taking the electron repulsion term, 1/Z, as the perturbation yields a series expansion in 1/Z where Z is the atomic number. In the energy formulation, approximate screening parameters are introduced for the relativistic and nonrelativistic energy parts allowing us to limit our calculation to the first order interelectron interaction. The energy values obtained are averaged over the spin and angular momentum quantum numbers, L and S as a function of the electron occupation numbers (k_{i}) for each individual electron shell. Up to seventeen different subshells have been considered i.e. each ionic state can be expressed in the form,{Q=1s^ {k_1} 2s^{k_2 } 2p^{k_3} 3s^ {k_4} 3p^{k_5 } 3d^{k_6} 4s^ {k_7} 4p^{k_8 } 4d^{k_9} 4f^ {k_{10}} 5s^{k _{11}}hfillcrquad 5p^{k_{12}} 5d ^{k_{13}}times5f ^{k_{14}} 5g^ {k_{15}} 6s^{k _{16}} 6p^{k_ {17}}.quadhfillcr} where k_{i} are different occupation numbers. This effective new computational method was applied and extended to analyze, for example the complex N and M x-ray emission spectra from the impact of highly charged Bi^{q+} (q = 71 to 54) ions on

  17. Radiation-thermal degradation of PE and PVC: Mechanism of synergism and dose rate effects

    NASA Astrophysics Data System (ADS)

    Clough, Roger L.; Gillen, Kenneth T.

    Polyethylene insulation and polyvinyl chloride jacketing materials that had been in use in a nuclear application were recently found to be substantially deteriorated. The damage had occurred under conditions where both the total estimated dose (about 2.5 Mrad) and the operating temperatures (about 43°C average) seemed relatively moderate. These results prompted us to initiate a program to study polyvinyl chloride and polyethylene degradation under conditions of combined γ-radiation and elevated temperature environments. A number of interesting aging effects were observed, including 1) a striking synergism between radiation and temperature and 2) strong dose-rate dependent effects which occur over a wide range of dose rates. The aging effects are explained in terms of a chain branching degradation mechanism involving thermally induced breakdown of peroxides which are formed in reactions initiated by the radiation. Evidence for this mechanism is derived from infrared spectra, from sequential radiation-elevated temperature experiments including experiments under inert atmosphere, from activation energy estimates and from a new technique involving treatment of intact samples with PH 3 for chemical reduction of peroxides. The results of our studies raise significant doubts about the utility of earlier compilations which purportedly serve as radiation life expectancy guides by indicating "tolerable radiation doses" for a variety of polymers.

  18. Effects of radiation types and dose rates on selected cable-insulating materials

    NASA Astrophysics Data System (ADS)

    Hanisch, F.; Maier, P.; Okada, S.; Schönbacher, H.

    A series of radiation tests have been carried out on halogen-free cable-insulating and cable-sheathing materials comprising commercial LDPE, EPR, EVA and SIR compounds. samples were irradiated at five different radiation sources, e.g. a nuclear reactor, fuel elements, a 60Co source, and in the stray radiation field of high-energy proton and electron accelerators at CERN and DESY. The integrated doses were within 50-5000 kGy and the dose rates within 10 mGy/s-70 Gy/s. Tensile tests and gel-fraction measurements were carried out. The results confirm that LDPEs are very sensitive to long-term ageing effects, and that important errors exceeding an order of magnitude can be made when assessing radiation damage by accelerated tests. On the other hand, well-stabilized LDPEs and the cross-linked rubber compounds do not show large dose-rate effects for the values given above. Furthermore, the interpretation of the elongation-at-break data and their relation to gel-fraction measurements show that radiation damage is related to the total absorbed dose irrespective of the different radiation types used in this experiment.

  19. Dose-rate dependent effects of ionizing radiation on vascular reactivity.

    PubMed

    Suvorava, T; Luksha, L; Bulanova, K Ya; Lobanok, L M

    2006-01-01

    This study was designed to investigate the dose-rate dependent effects of ionising radiation on endothelium- and NO-mediated reactivity of aorta and coronary vessels. Rats were exposed to acute ((137)Cs, 9 x 10(-4) Gy s(-1), 18 min) and chronic ((137)Cs, 2.8 x 10(-7) Gy s(-1), 41 days) radiation in 1 Gy dose. Acute irradiation transiently increased coronary flow in eNOS-activity-dependent manner on day 3 after exposure. In striking contrast, chronic irradiation caused a significant depression of coronary flow even on day 90 after irradiation and abolished the effects of NO-synthase inhibitor N-nitro-L-arginine methyl ester (10 micromol l(-1)). Furthermore, low intensity radiation strongly diminished the vasodilator properties of NO-donor sodium nitroprusside (5 micromol l(-1)). A similar pattern was observed in aortic rings. Endothelium-dependent vasodilation was increased on days 3 and 10 after acute irradiation, but strongly inhibited following chronic exposure for the entire post-radiation period. This was accompanied by a diminished vasodilator response to NO-donor on days 3, 10 and 30 of post-radiation but not on day 90. The data suggest that ionising radiation in 1 Gy induces changes of aortic and coronary vessels reactivity depending on the dose-rate and the interval after exposure.

  20. Gravity waves as a probe of the Hubble expansion rate during an electroweak scale phase transition

    SciTech Connect

    Chung, Daniel J. H.; Zhou Peng

    2010-07-15

    Just as big bang nucleosynthesis allows us to probe the expansion rate when the temperature of the Universe was around 1 MeV, the measurement of gravity waves from electroweak scale first order phase transitions may allow us to probe the expansion rate when the temperature of the Universe was at the electroweak scale. We compute the simple transformation rule for the gravity wave spectrum under the scaling transformation of the Hubble expansion rate. We then apply this directly to the scenario of quintessence kination domination and show how gravity wave spectra would shift relative to Laser Interferometer Space Antenna and Big Bang Observer projected sensitivities.

  1. On the transition rates of the Fe X and Fe XIV corona lines

    SciTech Connect

    Trabert, E

    2003-11-20

    Despite a considerable scatter of the theoretical predictions of the M1/E2 transition rate of the ''red iron line'' (FeX) in the solar corona, there is disagreement of all the results with the single measurement that used an electrostatic ion trap. Employing a heavy-ion storage ring for measuring the same transition in isoelectronic ions of Co, Ni, and Cu, the situation has been clarified, and a new data point for FeX can be determined by extrapolation. This result agrees with the basic atomic structure prediction for the line strength in combination with the experimental transition energy. For the ''green iron line'' (FeXIV), a recent measurement with an electron beam ion trap has resolved similar discrepancies.

  2. Temperature dependence of collisional rate coefficients for rotational transitions: a-type asymmetric top molecules

    NASA Astrophysics Data System (ADS)

    Sharma, M. K.; Sharma, M.; Chandra, S.

    2017-04-01

    On realizing that the rate coefficients for rotational transitions in the H2CS, H2CO, H2CC, H2CSi, due to collisions with He atom, under the IOS approximation, increase with the increase of kinetic temperature, we have looked analytically for 9 transitions in a-type asymmetric top molecules, because the results of Green et al. (1978) for H2CO do not increase for all the transitions, though they also are calculated under the IOS approximation. We tried to understand the source of discrepancy, but could not succeed, as the details of the work of Green et al. (1978) are not available. Data for other three molecules (H2CS, H2CC, H2CSi) are not available in the literature. Since our investigation is analytical, there is no reason not to believe our results.

  3. Casimir-Polder potential and transition rate in resonating cylindrical cavities

    SciTech Connect

    Ellingsen, Simen A.; Buhmann, Stefan Yoshi; Scheel, Stefan

    2010-09-15

    We consider the Casimir-Polder potential of particles placed inside a metallic cylindrical cavity at finite temperatures, taking account of thermal nonequilibrium effects. In particular, we study how the resonant (thermal nonequilibrium) potential and transition rates can be enhanced by fine tuning the radius of the cavity to match the transition wavelength of the dominant transitions of the particle. Numerical calculations show that the cavity-induced energy-level shift of atoms prepared in low-lying Rydberg states can be enhanced beyond 30 kHz, which is within the range of observability of modern experiments. Because the magnitude of the resonance peaks depends sensitively on the low-frequency dissipation of the cavity metal, experiments in this setup could be a critical test of the disputed thermal correction to the Casimir force between metal plates.

  4. Ionizing radiation sensitivity of the ocular lens and its dose rate dependence.

    PubMed

    Hamada, Nobuyuki

    2017-10-01

    In 2011, the International Commission on Radiological Protection reduced the threshold for the lens effects of low linear energy transfer (LET) radiation. On one hand, the revised threshold of 0.5 Gy is much lower than previously recommended thresholds, but mechanisms behind high radiosensitivity remain incompletely understood. On the other hand, such a threshold is independent of dose rate, in contrast to previously recommended separate thresholds each for single and fractionated/protracted exposures. Such a change was made predicated on epidemiological evidence suggesting that a threshold for fractionated/protracted exposures is not higher than an acute threshold, and that a chronic threshold is uncertain. Thus, the dose rate dependence is still unclear. This paper therefore reviews the current knowledge on the radiosensitivity of the lens and the dose rate dependence of radiation cataractogenesis, and discusses its mechanisms. Mounting biological evidence indicates that the lens cells are not necessarily radiosensitive to cell killing, and the high radiosensitivity of the lens thus appears to be attributable to other mechanisms (e.g., excessive proliferation, abnormal differentiation, a slow repair of DNA double-strand breaks, telomere, senescence, crystallin changes, non-targeted effects and inflammation). Both biological and epidemiological evidence generally supports the lack of dose rate effects. However, there is also biological evidence for the tissue sparing dose rate (or fractionation) effect of low-LET radiation and an enhancing inverse dose fractionation effect of high-LET radiation at a limited range of LET. Emerging epidemiological evidence in chronically exposed individuals implies the inverse dose rate effect. Further biological and epidemiological studies are warranted to gain deeper knowledge on the radiosensitivity of the lens and dose rate dependence of radiation cataractogenesis.

  5. Characterization of Fast-Electron Beam Propagation Through Solid-Density Matter by Optical Transition Radiation

    NASA Astrophysics Data System (ADS)

    Storm, M.; Myatt, J.; Stoeckl, C.

    2006-10-01

    A diagnostic has been developed to measure the emission of optical transition radiation (OTR) produced by relativistic electrons emerging at the rear side of laser-illuminated targets. The device will be deployed in the newly completed multiterawatt (MTW) experimental facility at the University of Rochester's Laboratory for Laser Energetics. The MTW laser is capable of producing 10-J, 600-fs pulses of 1053-nm-wavelength radiation, which are focused using an f/2 off-axis parabolic mirror to intensities in excess of 10^19 Wcm-2. A 20x microscope objective with a resolution of better than 1 μm will image the OTR signal onto a CCD camera. A postprocessor to the particle-in-cell code LSP will be used to generate a simulated OTR signal from the calculated fast-electron distributions at the rear side of the target for comparison with experimental data. This talk will present the characteristics and capabilities of the OTR device along with the most recently acquired data. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-92SF19460.

  6. Interference of diffraction and transition radiation and its application as a beam divergence diagnostic

    NASA Astrophysics Data System (ADS)

    Fiorito, R. B.; Shkvarunets, A. G.; Watanabe, T.; Yakimenko, V.; Snyder, D.

    2006-05-01

    We have observed the interference of optical diffraction radiation (ODR) and optical transition radiation (OTR) produced by the interaction of a relativistic electron beam with a micromesh foil and a mirror. The production of forward directed ODR from electrons passing through the holes and wires of the mesh and their separate interactions with backward OTR from the mirror are analyzed with the help of a simulation code. By careful choice of the micromesh properties, mesh-mirror spacing, observation wavelength, and filter band pass, the interference of the ODR produced from the unperturbed electrons passing through the open spaces of the mesh and OTR from the mirror are observable above a broad incoherent background from interaction of the heavily scattered electrons passing through the mesh wires. These interferences (ODTRI) are sensitive to the beam divergence and can be used to directly diagnose this parameter. We compare experimental divergence values obtained using ODTRI, conventional OTRI, for the case when front foil scattering is negligible, and computed values obtained from transport code calculations and multiple screen beam size measurements. We obtain good agreement in all cases.

  7. Radiation Dose-Rate Effects on Gene Expression in a Mouse Biodosimetry Model

    PubMed Central

    Paul, Sunirmal; Smilenov, Lubomir B.; Elliston, Carl D.; Amundson, Sally A.

    2015-01-01

    In the event of a nuclear accident or radiological terrorist attack, there will be a pressing need for biodosimetry to triage a large, potentially exposed population and to assign individuals to appropriate treatment. Exposures from fallout are likely, resulting in protracted dose delivery that would, in turn, impact the extent of injury. Biodosimetry approaches that can distinguish such low-dose-rate (LDR) exposures from acute exposures have not yet been developed. In this study, we used the C57BL/6 mouse model in an initial investigation of the impact of low-dose-rate delivery on the transcriptomic response in blood. While a large number of the same genes responded to LDR and acute radiation exposures, for many genes the magnitude of response was lower after LDR exposures. Some genes, however, were differentially expressed (P < 0.001, false discovery rate < 5%) in mice exposed to LDR compared with mice exposed to acute radiation. We identified a set of 164 genes that correctly classified 97% of the samples in this experiment as exposed to acute or LDR radiation using a support vector machine algorithm. Gene expression is a promising approach to radiation biodosimetry, enhanced greatly by this first demonstration of its potential for distinguishing between acute and LDR exposures. Further development of this aspect of radiation biodosimetry, either as part of a complete gene expression biodosimetry test or as an adjunct to other methods, could provide vital triage information in a mass radiological casualty event. PMID:26114327

  8. Thermal radiative near field transport between vanadium dioxide and silicon oxide across the metal insulator transition

    SciTech Connect

    Menges, F.; Spieser, M.; Riel, H.; Gotsmann, B.; Dittberner, M.; Novotny, L.; Passarello, D.; Parkin, S. S. P.

    2016-04-25

    The thermal radiative near field transport between vanadium dioxide and silicon oxide at submicron distances is expected to exhibit a strong dependence on the state of vanadium dioxide which undergoes a metal-insulator transition near room temperature. We report the measurement of near field thermal transport between a heated silicon oxide micro-sphere and a vanadium dioxide thin film on a titanium oxide (rutile) substrate. The temperatures of the 15 nm vanadium dioxide thin film varied to be below and above the metal-insulator-transition, and the sphere temperatures were varied in a range between 100 and 200 °C. The measurements were performed using a vacuum-based scanning thermal microscope with a cantilevered resistive thermal sensor. We observe a thermal conductivity per unit area between the sphere and the film with a distance dependence following a power law trend and a conductance contrast larger than 2 for the two different phase states of the film.

  9. Critical desertification transition in semi-arid ecosystems: The role of local facilitation and colonization rate

    NASA Astrophysics Data System (ADS)

    Corrado, Raffaele; Cherubini, Anna Maria; Pennetta, Cecilia

    2015-05-01

    In this work we study the effect of two different ecological mechanisms on the desertification transition in arid or semi-arid ecosystems, modeled by a stochastic cellular automaton. Namely we consider the role of the facilitation mechanism, i.e. the local positive effects of plants on their neighborhood and of colonization factors, such as seed production, survival and germination probabilities. Within the model, the strength of these two mechanisms is determined by the parameters f and b, respectively controlling the rates of the recovery and colonization processes. In particular we focus on the full desertification transition occurring at increasing value of the mortality rate m and we discuss how the values of f and b affect the critical mortality mc , the critical exponents β and γσ‧, determining the power-law scaling of the average vegetation density and of the root-mean-square deviation of the density fluctuations, and the character of the transition: continuous or abrupt. We show that mc strongly depends on both f and b, a dependence which accounts for the higher resilience of the ecosystems to external stresses as a consequence of an increased effectiveness of positive feedback effects. On the other hand, concerning the value of the exponents and the character of the transition, our results point out that both these features are unaffected by changes in the strength of the local facilitation. Viceversa, we show that an increase of the colonization factor b significantly modifies the values of the exponents and the order of the transition, changing a continuous transition into an abrupt one. We explain these results in terms of the different range of the interactions characterizing facilitation and colonization mechanisms.

  10. Black holes in short period X-ray binaries and the transition to radiatively inefficient accretion

    NASA Astrophysics Data System (ADS)

    Knevitt, G.; Wynn, G. A.; Vaughan, S.; Watson, M. G.

    2014-02-01

    By comparing the orbital period distributions of black hole and neutron star low-mass X-ray binaries (LMXBs) in the Ritter-Kolb catalogue we show that there is statistical evidence for a dearth of black hole systems at short orbital periods (Porb < 4 h). This could either be due to a true divergence in orbital period distributions of these two types of system, or to black hole LMXBs being preferentially hidden from view at short orbital periods. We explore the latter possibility, by investigating whether black hole LMXBs could be concealed by a switch to radiatively inefficient accretion at low luminosities. The peak luminosity and the duration of X-ray binary outbursts are related to the disc radius and, hence, the orbital period. At short periods, where the peak outburst luminosity drops close to the threshold for radiatively inefficient accretion, black hole LMXBs have lower outburst luminosities, shorter outburst durations and lower X-ray duty cycles than comparable neutron star systems. These factors can combine to severely reduce the detection probability of short period black hole LMXBs relative to those containing neutron stars. We estimate the outburst properties and orbital period distribution of black hole LMXBs using two models of the transition to radiatively inefficient accretion: an instantaneous drop in accretion efficiency (η) to zero, at a fraction (f) of the Eddington luminosity (LEdd) and a power-law efficiency decrease, η ∝ dot{M}^n, for L < f LEdd. We show that a population of black hole LMXBs at short orbital periods can only be hidden by a sharp drop in efficiency, either instantaneous or for n ≳ 3. This could be achieved by a genuine drop in luminosity or through abrupt spectral changes that shift the accretion power out of a given X-ray band.

  11. Low-dose or low-dose-rate ionizing radiation-induced bioeffects in animal models.

    PubMed

    Tang, Feng Ru; Loke, Weng Keong; Khoo, Boo Cheong

    2017-03-01

    Animal experimental studies indicate that acute or chronic low-dose ionizing radiation (LDIR) (≤100 mSv) or low-dose-rate ionizing radiation (LDRIR) (<6 mSv/h) exposures may be harmful. It induces genetic and epigenetic changes and is associated with a range of physiological disturbances that includes altered immune system, abnormal brain development with resultant cognitive impairment, cataractogenesis, abnormal embryonic development, circulatory diseases, weight gain, premature menopause in female animals, tumorigenesis and shortened lifespan. Paternal or prenatal LDIR/LDRIR exposure is associated with reduced fertility and number of live fetuses, and transgenerational genomic aberrations. On the other hand, in some experimental studies, LDIR/LDRIR exposure has also been reported to bring about beneficial effects such as reduction in tumorigenesis, prolonged lifespan and enhanced fertility. The differences in reported effects of LDIR/LDRIR exposure are dependent on animal genetic background (susceptibility), age (prenatal or postnatal days), sex, nature of radiation exposure (i.e. acute, fractionated or chronic radiation exposure), type of radiation, combination of radiation with other toxic agents (such as smoking, pesticides or other chemical toxins) or animal experimental designs. In this review paper, we aimed to update radiation researchers and radiologists on the current progress achieved in understanding the LDIR/LDRIR-induced bionegative and biopositive effects reported in the various animal models. The roles played by a variety of molecules that are implicated in LDIR/LDRIR-induced health effects will be elaborated. The review will help in future investigations of LDIR/LDRIR-induced health effects by providing clues for designing improved animal research models in order to clarify the current controversial/contradictory findings from existing studies. © The Author 2017. Published by Oxford University Press on behalf of The Japan Radiation Research

  12. Transitions.

    ERIC Educational Resources Information Center

    Nathanson, Jeanne H., Ed.

    1993-01-01

    This theme issue on transitions for individuals with disabilities contains nine papers discussing transition programs and issues. "Transition Issues for the 1990s," by Michael J. Ward and William D. Halloran, discusses self-determination, school responsibility for transition, continued educational engagement of at-risk students, and service…

  13. Terrestrial gamma radiation dose rate in Ryukyu Islands, subtropical region of Japan.

    PubMed

    Furukawa, M; Kina, S; Shiroma, M; Shiroma, Y; Masuda, N; Motomura, D; Hiraoka, H; Fujioka, S; Kawakami, T; Yasuda, Y; Arakawa, K; Fukahori, K; Jyunicho, M; Ishikawa, S; Ohomoto, T; Shingaki, R; Akata, N; Zhuo, W; Tokonami, S

    2015-11-01

    In order to explain the distribution of natural radiation level in the Asia, in situ measurements of dose rate in air due to terrestrial gamma radiation have been conducted in a total of 21 islands that belong to Ryukyu Islands (Ryukyu Archipelago), subtropical rejoin of southwest Japan. Car-borne surveys have also been carried out in Okinawa-jima, the biggest island of the archipelago. Based on the results for these measurements, arithmetic mean, the maximum and the minimum of the dose rates at 1 m in height from the unpaved soil ground in the archipelago were estimated to be 47, 165 and 8 nGy h(-1), respectively. A comparative study of car-borne data obtained prior to and subsequent to the 2011 Fukushima nuclear accident, as for Okinawa-jima, indicated that the nuclear accident has no impact on the environmental radiation at the present time.

  14. Remote Sensing of Radiation Dose Rate by Customizing an Autonomous Robot

    NASA Astrophysics Data System (ADS)

    Kobayashi, T.; Nakahara, M.; Morisato, K.; Takashina, T.; Kanematsu, H.

    2012-03-01

    Distribution of radiation dose was measured by customizing an autonomous cleaning robot "Roomba" and a scintillation counter. The robot was used as a vehicle carrying the scintillation survey meter, and was additionally equipped with an H8 micro computer to remote-control the vehicle and to send measured data. The data obtained were arranged with position data, and then the distribution map of the radiation dose rate was produced. Manual, programmed and autonomous driving tests were conducted, and all performances were verified. That is, for each operational mode, the measurements both with moving and with discrete moving were tried in and outside of a room. Consequently, it has been confirmed that remote sensing of radiation dose rate is possible by customizing a robot on market.

  15. Dominant Frequency Increase Rate Predicts Transition from Paroxysmal to Long-Term Persistent Atrial Fibrillation

    PubMed Central

    Martins, Raphael P.; Kaur, Kuljeet; Hwang, Elliot; Ramirez, Rafael J.; Willis, B. Cicero; Filgueiras-Rama, David; Ennis, Steven R.; Takemoto, Yoshio; Ponce-Balbuena, Daniela; Zarzoso, Manuel; O’Connell, Ryan P.; Musa, Hassan; Guerrero-Serna, Guadalupe; Avula, Uma Mahesh R.; Swartz, Michael F.; Bhushal, Sandesh; Deo, Makarand; Pandit, Sandeep V.; Berenfeld, Omer; Jalife, José

    2014-01-01

    Background Little is known about the mechanisms underlying the transition from paroxysmal to persistent atrial fibrillation (AF). In an ovine model of long-standing persistent AF (LS-PAF) we tested the hypothesis that the rate of electrical and/or structural remodeling, assessed by dominant frequency (DF) changes, determines the time at which AF becomes persistent. Methods and Results Self-sustained AF was induced by atrial tachypacing. Seven sheep were sacrificed 11.5±2.3 days after the transition to persistent AF and without reversal to sinus rhythm (SR); 7 sheep were sacrificed after 341.3±16.7 days of LS-PAF. Seven sham-operated animals were in SR for 1 year. DF was monitored continuously in each group. RT-PCR, western blotting, patch-clamping and histological analyses were used to determine changes in functional ion channel expression and structural remodeling. Atrial dilatation, mitral valve regurgitation, myocyte hypertrophy, and atrial fibrosis occurred progressively and became statistically significant after the transition to persistent AF, with no evidence for left ventricular dysfunction. DF increased progressively during the paroxysmal-to-persistent AF transition and stabilized when AF became persistent. Importantly, the rate of DF increase (dDF/dt) correlated strongly with the time to persistent AF. Significant action potential duration (APD) abbreviation, secondary to functional ion channel protein expression changes (CaV1.2, NaV1.5 and KV4.2 decrease; Kir2.3 increase), was already present at the transition and persisted for one-year follow up. Conclusions In the sheep model of LS-PAF, the rate of DF increase predicts the time at which AF stabilizes and becomes persistent, reflecting changes in APD and densities of sodium, L-type calcium and inward rectifier currents. PMID:24463369

  16. Characterization of amorphous solids with weak glass transitions using high ramp rate differential scanning calorimetry.

    PubMed

    Katayama, Derrick S; Carpenter, John F; Manning, Mark Cornell; Randolph, Theodore W; Setlow, Peter; Menard, Kevin P

    2008-02-01

    Measurement of the glass transition temperature (T(g)) of proteins and other high molecular weight polymers in the amorphous state is often difficult, since the transition is extremely weak, that is, the DeltaC(p) at the glass transition temperature is small. For example, little is known about the solid-state properties of hydroxyethyl starch (HES), which is beginning to become more commonly evaluated as a bulking agent in pharmaceutical products. For weak thermal events, such as the change in heat capacity at the T(g) of a pure protein or large synthetic polymer, increased heating rate should produce greater sensitivity in terms of heat flow. Recent innovations in rapid scanning technology for differential scanning calorimetry (DSC) allow measurements on materials where the thermal events are difficult to detect by conventional DSC. In the current study, measurements of the T(g) of proteins in the solid state, amorphous pharmaceutical excipients which have small DeltaC(p) at the glass transition temperature, and bacterial spores, have all been made using high ramp rate DSC, providing information on materials that was inaccessible using conventional DSC methods.

  17. Radiosensitization of Human Cervical Cancer Cells by Inhibiting Ribonucleotide Reductase: Enhanced Radiation Response at Low-Dose Rates

    SciTech Connect

    Kunos, Charles A.; Colussi, Valdir C.; Pink, John; Radivoyevitch, Tomas; Oleinick, Nancy L.

    2011-07-15

    Purpose: To test whether pharmacologic inhibition of ribonucleotide reductase (RNR) by 3-aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP, NSC no. 663249) enhances radiation sensitivity during low-dose-rate ionizing radiation provided by a novel purpose-built iridium-192 cell irradiator. Methods and Materials: The cells were exposed to low-dose-rate radiation (11, 23, 37, 67 cGy/h) using a custom-fabricated cell irradiator or to high-dose-rate radiation (330 cGy/min) using a conventional cell irradiator. The radiation sensitivity of human cervical (CaSki, C33-a) cancer cells with or without RNR inhibition by 3-AP was evaluated using a clonogenic survival and an RNR activity assay. Alteration in the cell cycle distribution was monitored using flow cytometry. Results: Increasing radiation sensitivity of both CaSki and C33-a cells was observed with the incremental increase in radiation dose rates. 3-AP treatment led to enhanced radiation sensitivity in both cell lines, eliminating differences in cell cytotoxicity from the radiation dose rate. RNR blockade by 3-AP during low-dose-rate irradiation was associated with low RNR activity and extended G{sub 1}-phase cell cycle arrest. Conclusions: We conclude that RNR inhibition by 3-AP impedes DNA damage repair mechanisms that rely on deoxyribonucleotide production and thereby increases radiation sensitivity of human cervical cancers to low-dose-rate radiation.

  18. Multi-Level Effects of Low Dose Rate Ionizing Radiation on Southern Toad, Anaxyrus [Bufo] terrestris

    PubMed Central

    Stark, Karolina; Scott, David E.; Tsyusko, Olga; Coughlin, Daniel P.; Hinton, Thomas G.

    2015-01-01

    Despite their potential vulnerability to contaminants from exposure at multiple life stages, amphibians are one of the least studied groups of vertebrates in ecotoxicology, and research on radiation effects in amphibians is scarce. We used multiple endpoints to assess the radiosensitivity of the southern toad (Anaxyrus [Bufo] terrestris) during its pre-terrestrial stages of development –embryonic, larval, and metamorphic. Toads were exposed, from several hours after oviposition through metamorphosis (up to 77 days later), to four low dose rates of 137Cs at 0.13, 2.4, 21, and 222 mGy d-1, resulting in total doses up to 15.8 Gy. Radiation treatments did not affect hatching success of embryos, larval survival, or the length of the larval period. The individual family variation in hatching success of embryos was larger than the radiation response. In contrast, newly metamorphosed individuals from the higher dose-rate treatments had higher mass and mass/length body indices, a measure which may relate to higher post-metamorphic survival. The increased mass and index at higher dose rates may indicate that the chronic, low dose rate radiation exposures triggered secondary responses. Additionally, the increases in growth were linked to a decrease in DNA damage (as measured by the Comet Assay) in red blood cells at a dose rate of 21 mGy d-1 and a total dose of 1.1 Gy. In conclusion, the complex effects of low dose rates of ionizing radiation may trigger growth and cellular repair mechanisms in amphibian larvae. PMID:25927361

  19. Multi-level effects of low dose rate ionizing radiation on southern toad, Anaxyrus [Bufo] terrestris

    DOE PAGES

    Stark, Karolina; Scott, David E.; Tsyusko, Olga; ...

    2015-04-30

    Despite their potential vulnerability to contaminants from exposure at multiple life stages, amphibians are one of the least studied groups of vertebrates in ecotoxicology, and research on radiation effects in amphibians is scarce. We used multiple endpoints to assess the radiosensitivity of the southern toad (Anaxyrus [Bufo] terrestris) during its pre-terrestrial stages of development –embryonic, larval, and metamorphic. Toads were exposed, from several hours after oviposition through metamorphosis (up to 77 days later), to four low dose rates of ¹³⁷Cs at 0.13, 2.4, 21, and 222 mGy d⁻¹, resulting in total doses up to 15.8 Gy. Radiation treatments did notmore » affect hatching success of embryos, larval survival, or the length of the larval period. The individual family variation in hatching success of embryos was larger than the radiation response. In contrast, newly metamorphosed individuals from the higher dose-rate treatments had higher mass and mass/length body indices, a measure which may relate to higher post-metamorphic survival. The increased mass and index at higher dose rates may indicate that the chronic, low dose rate radiation exposures triggered secondary responses. Additionally, the increases in growth were linked to a decrease in DNA damage (as measured by the Comet Assay) in red blood cells at a dose rate of 21mGy d⁻¹ and a total dose of 1.1 Gy. In conclusion, the complex effects of low dose rates of ionizing radiation may trigger growth and cellular repair mechanisms in amphibian larvae.« less

  20. Multi-Level Effects of Low Dose Rate Ionizing Radiation on Southern Toad, Anaxyrus [Bufo] terrestris.

    PubMed

    Stark, Karolina; Scott, David E; Tsyusko, Olga; Coughlin, Daniel P; Hinton, Thomas G

    2015-01-01

    Despite their potential vulnerability to contaminants from exposure at multiple life stages, amphibians are one of the least studied groups of vertebrates in ecotoxicology, and research on radiation effects in amphibians is scarce. We used multiple endpoints to assess the radiosensitivity of the southern toad (Anaxyrus [Bufo] terrestris) during its pre-terrestrial stages of development -embryonic, larval, and metamorphic. Toads were exposed, from several hours after oviposition through metamorphosis (up to 77 days later), to four low dose rates of 137Cs at 0.13, 2.4, 21, and 222 mGy d-1, resulting in total doses up to 15.8 Gy. Radiation treatments did not affect hatching success of embryos, larval survival, or the length of the larval period. The individual family variation in hatching success of embryos was larger than the radiation response. In contrast, newly metamorphosed individuals from the higher dose-rate treatments had higher mass and mass/length body indices, a measure which may relate to higher post-metamorphic survival. The increased mass and index at higher dose rates may indicate that the chronic, low dose rate radiation exposures triggered secondary responses. Additionally, the increases in growth were linked to a decrease in DNA damage (as measured by the Comet Assay) in red blood cells at a dose rate of 21 mGy d-1 and a total dose of 1.1 Gy. In conclusion, the complex effects of low dose rates of ionizing radiation may trigger growth and cellular repair mechanisms in amphibian larvae.

  1. Development rate of PMMA exposed to synchrotron x-ray radiation for LIGA applications

    NASA Astrophysics Data System (ADS)

    McNamara, Shamus

    2011-01-01

    This paper investigates the development rate of poly(methyl methacrylate) (PMMA) after it is exposed to synchrotron x-ray radiation. The x-ray exposures were performed at both Synchrotron Radiation Center and Brookhaven National Laboratories. The development rate of PMMA in a variety of developers was measured as a function of absorbed x-ray dose (J cm-3). The development rate of four different types of PMMA was investigated: unexposed 950k PMMA, Cryo GMS PMMA, Goodfellow CQ PMMA, and Crosslinked PMMA. It was found that the development rate is the same for all types of PMMA studied. The temperature dependence of one developer, GG developer, was studied in detail and it is shown that the selectivity of exposed to unexposed PMMA increases as the temperature is reduced. This work was performed in part at the University of Wisconsin.

  2. Accelerated tests for bounding the low dose rate radiation response of lateral PNP bipolar junction transistors

    SciTech Connect

    Witczak, S.C.; Schrimpf, R.D.; Galloway, K.F.; Schmidt, D.M.; Fleetwood, D.M.; Pease, R.L.; Coombs, W.E.; Suehle, J.S.

    1996-03-01

    Low dose rate gain degradation of lateral pnp bipolar transistors can be simulated by accelerated irradiations performed at approximately 135 degrees C. Degradation enhancement is explained by temperature- dependent radiation-induced interface trap formation above the transistor`s base.

  3. Influence of Space Radiation on the Outgassing Rate of a Patterned Polymeric Composite in Vacuum

    SciTech Connect

    Khasanshin, R. H.; Timofeev, A. N.; Ivanov, M. F.

    2009-01-05

    Experimental results on outgassing rates of patterned polymeric composites preliminary subjected to separate and combined radiation have been analyzed and presented. Mathematical models describing the outgassing processes in these materials were used for interpretation of the experimental data. Numerical results found using the models are presented.

  4. Nested radiations and the pulse of angiosperm diversification: increased diversification rates often follow whole genome duplications.

    PubMed

    Tank, David C; Eastman, Jonathan M; Pennell, Matthew W; Soltis, Pamela S; Soltis, Douglas E; Hinchliff, Cody E; Brown, Joseph W; Sessa, Emily B; Harmon, Luke J

    2015-07-01

    Our growing understanding of the plant tree of life provides a novel opportunity to uncover the major drivers of angiosperm diversity. Using a time-calibrated phylogeny, we characterized hot and cold spots of lineage diversification across the angiosperm tree of life by modeling evolutionary diversification using stepwise AIC (MEDUSA). We also tested the whole-genome duplication (WGD) radiation lag-time model, which postulates that increases in diversification tend to lag behind established WGD events. Diversification rates have been incredibly heterogeneous throughout the evolutionary history of angiosperms and reveal a pattern of 'nested radiations' - increases in net diversification nested within other radiations. This pattern in turn generates a negative relationship between clade age and diversity across both families and orders. We suggest that stochastically changing diversification rates across the phylogeny explain these patterns. Finally, we demonstrate significant statistical support for the WGD radiation lag-time model. Across angiosperms, nested shifts in diversification led to an overall increasing rate of net diversification and declining relative extinction rates through time. These diversification shifts are only rarely perfectly associated with WGD events, but commonly follow them after a lag period. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  5. High-rate deposition of MgO by reactive ac pulsed magnetron sputtering in the transition mode

    SciTech Connect

    Kupfer, H.; Kleinhempel, R.; Richter, F.; Peters, C.; Krause, U.; Kopte, T.; Cheng, Y.

    2006-01-15

    A reactive ac pulsed dual magnetron sputtering process for MgO thin-film deposition was equipped with a closed-loop control of the oxygen flow rate (F{sub O2}) using the 285 nm magnesium radiation as input. Owing to this control, most of the unstable part of the partial pressure versus flowrate curve became accessible. The process worked steadily and reproducible without arcing. A dynamic deposition rate of up to 35 nm m/min could be achieved, which was higher than in the oxide mode by about a factor of 18. Both process characteristics and film properties were investigated in this work in dependence on the oxygen flow, i.e., in dependence on the particular point within the transition region where the process is operated. The films had very low extinction coefficients (<5x10{sup -5}) and refractive indices close to the bulk value. They were nearly stoichiometric with a slight oxygen surplus (Mg/O=48/52) which was independent of the oxygen flow. X-ray diffraction revealed a prevailing (111) orientation. Provided that appropriate rf plasma etching was performed prior to deposition, no other than the (111) peak could be detected. The intensity of this peak increased with increasing F{sub O{sub 2}}, indicating an even more pronounced (111) texture. The ion-induced secondary electron emission coefficient (iSEEC) was distinctly correlated with the markedness of the (111) preferential orientation. Both refractive index and (111) preferred orientation (which determines the iSEEC) were found to be improved in comparison with the MgO growth in the fully oxide mode. Consequently, working in the transition mode is superior to the oxide mode not only with respect to the growth rate, but also to most important film properties.

  6. Excitation energies, radiative and autoionization rates, dielectronic satellite lines, and dielectronic recombination rates for excited states of Yb-like W

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, P.; Safronova, U. I.; Safronova, A. S.

    2012-06-01

    Energy levels, radiative transition probabilities, and autoionization rates for [Cd]4f^145p^65l'nl, [Cd]4f^145p^66l''nl, [Cd]4f^145p^55d^2nl, [Cd]4f^145p^55d6l''nl, [Cd]4f^135p^65d^2nl, and [Cd]4f^135p^65d6l''nl (l'=d, f, g , l''=s,p,d,f, g, n=5-7) states of Yb-like tungsten (W^4+) are calculated using the RMBPT, HULLAC, and COWAN codes. Branching ratios relative to the [Cd]4f^145p^65d, [Cd]4f^145p^66s, and [Cd]4f^145p^66p thresholds in Tm-like tungsten and intensity factors are calculated for satellite lines, and dielectronic recombination (DR) rate coefficients are determined for the singly excited, as well as non-autoionizing core-excited states in Yb-like tungsten. Contributions from the autoionizing doubly excited states and core-excited states (with n up to 100), which are particulary important for calculating total DR rates, are estimated. Synthetic dielectronic satellite spectra from Yb-like W are simulated in a broad spectral range from 200 to 1400 å. These calculations provide recommended values critically evaluated for their accuracy for a number of W^4+ properties useful for a variety of applications including for fusion applications.

  7. Tumor cure studies on the rat sarcoma BA1112 using continuous low-dose-rate radiation

    SciTech Connect

    Peschel, R.E.; Martin, D.F.; Fischer, J.J.

    1984-09-01

    Delivery of continous low-dose-rate radiation at a constant rate using an afterloading plastic helmet system can achieve the local cure of the BA1112 rat sarcoma. Complete dose response curves for local tumor cure have been obtained at 170 rad (1.7 Gy) and 130 rad (1.3 Gy) per hour. The results are consistent with the known radiobiological properties of the BA1112 tumor.

  8. An analysis of the SEU rate of microcircuits exposed by the various components of space radiation.

    PubMed

    Bashkirov, V F; Kuznetsov, N V; Nymmik, R A

    1999-06-01

    In the present paper the experimental and calculated data of SEU rate in microcircuits operating onboard spacecraft are compared. The main features of models and the calculation methods, which are incorporated in the SEREIS software package, are considered. The main features of models, and the calculation methods are considered. The contribution of the different space radiation components (ERB Protons; GCR particles and SEPs) to the SEU rate is discussed with an allowance for the shielding thickness.

  9. Space Radiation Quality Factors and the Delta Ray Dose and Dose-Rate Reduction Effectiveness Factor.

    PubMed

    Cucinotta, Francis A; Cacao, Eliedonna; Alp, Murat

    2016-03-01

    In this paper, the authors recommend that the dose and dose-rate effectiveness factor used for space radiation risk assessments should be based on a comparison of the biological effects of energetic electrons produced along a cosmic ray particles path in low fluence exposures to high dose-rate gamma-ray exposures of doses of about 1 Gy. Methods to implement this approach are described.

  10. Deducing the Kinetics of Protein Synthesis In Vivo from the Transition Rates Measured In Vitro

    PubMed Central

    Rudorf, Sophia; Thommen, Michael; Rodnina, Marina V.; Lipowsky, Reinhard

    2014-01-01

    The molecular machinery of life relies on complex multistep processes that involve numerous individual transitions, such as molecular association and dissociation steps, chemical reactions, and mechanical movements. The corresponding transition rates can be typically measured in vitro but not in vivo. Here, we develop a general method to deduce the in-vivo rates from their in-vitro values. The method has two basic components. First, we introduce the kinetic distance, a new concept by which we can quantitatively compare the kinetics of a multistep process in different environments. The kinetic distance depends logarithmically on the transition rates and can be interpreted in terms of the underlying free energy barriers. Second, we minimize the kinetic distance between the in-vitro and the in-vivo process, imposing the constraint that the deduced rates reproduce a known global property such as the overall in-vivo speed. In order to demonstrate the predictive power of our method, we apply it to protein synthesis by ribosomes, a key process of gene expression. We describe the latter process by a codon-specific Markov model with three reaction pathways, corresponding to the initial binding of cognate, near-cognate, and non-cognate tRNA, for which we determine all individual transition rates in vitro. We then predict the in-vivo rates by the constrained minimization procedure and validate these rates by three independent sets of in-vivo data, obtained for codon-dependent translation speeds, codon-specific translation dynamics, and missense error frequencies. In all cases, we find good agreement between theory and experiment without adjusting any fit parameter. The deduced in-vivo rates lead to smaller error frequencies than the known in-vitro rates, primarily by an improved initial selection of tRNA. The method introduced here is relatively simple from a computational point of view and can be applied to any biomolecular process, for which we have detailed information

  11. Determination of the ductile-brittle transition temperature from the microplastic-strain rate

    NASA Astrophysics Data System (ADS)

    Andreev, A. K.; Solntsev, Yu. P.

    2008-04-01

    The possibility of the determination of the tendency of cast and deformed steels to brittle fracture using the temperature dependence of the small-plastic-strain rate is studied. The temperature corresponding to the maximum in this curve is found to indicate an abrupt decrease in the steel plasticity, which makes it possible to interpret it as the ductile-brittle transition temperature depending only on the structure of a material.

  12. Optimal Control of Markov Processes with Age-Dependent Transition Rates

    SciTech Connect

    Ghosh, Mrinal K. Saha, Subhamay

    2012-10-15

    We study optimal control of Markov processes with age-dependent transition rates. The control policy is chosen continuously over time based on the state of the process and its age. We study infinite horizon discounted cost and infinite horizon average cost problems. Our approach is via the construction of an equivalent semi-Markov decision process. We characterise the value function and optimal controls for both discounted and average cost cases.

  13. A general method for calculating the mean transit times and distribution rate parameters of catenary metabolites.

    PubMed

    Cheng, H

    1992-04-01

    A general method for calculating the mean transit times and distribution rate parameters is described. The calculations require the AUC, AUMC, and derivatives of the plasma concentration profiles of the metabolites and its precursor. The method is applicable to catenary metabolites with any precursor order and does not require separate administration of the metabolite. The approach is applied to published data for the primary and secondary metabolites of ketamine.

  14. Using RADFET for the real-time measurement of gamma radiation dose rate

    NASA Astrophysics Data System (ADS)

    Andjelković, Marko S.; Ristić, Goran S.; Jakšić, Aleksandar B.

    2015-02-01

    RADFETs (RADiation sensitive Field Effect Transistors) are integrating ionizing radiation dosimeters operating on the principle of conversion of radiation-induced threshold voltage shift into absorbed dose. However, one of the major drawbacks of RADFETs is the inability to provide the information on the dose rate in real-time using the conventional absorbed dose measurement technique. The real-time monitoring of dose rate and absorbed dose can be achieved with the current mode dosimeters such as PN and PIN diodes/photodiodes, but these dosimeters have some limitations as absorbed dose meters and hence they are often not a suitable replacement for RADFETs. In that sense, this paper investigates the possibility of using the RADFET as a real-time dose rate meter so that it could be applied for simultaneous online measurement of the dose rate and absorbed dose. A RADFET sample, manufactured by Tyndall National Institute, Cork, Ireland, was tested as a dose rate meter under gamma irradiation from a Co-60 source. The RADFET was configured as a PN junction, such that the drain, gate and source terminals were grounded, while the radiation-induced current was measured at the bulk terminal, whereby the bulk was successively biased with 0 , 10 , 20  and 30 V. In zero-bias mode the radiation-induced current was unstable, but in the biased mode the current response was stable for the investigated dose rates from 0.65  to 32.1 Gy h-1 and up to the total absorbed dose of 25 Gy. The current increased with the dose rate in accordance with the power law, whereas the sensitivity of the current read-out was linear with respect to the applied bias voltage. Comparison with previously analyzed PIN photodiodes has shown that the investigated RADFET is competitive with PIN photodiodes as a gamma radiation dose rate meter and therefore has the potential to be employed for the real-time monitoring of the dose rate and absorbed dose.

  15. Rates of change in natural and anthropogenic radiative forcing over the past 20,000 years

    PubMed Central

    Joos, Fortunat; Spahni, Renato

    2008-01-01

    The rate of change of climate codetermines the global warming impacts on natural and socioeconomic systems and their capabilities to adapt. Establishing past rates of climate change from temperature proxy data remains difficult given their limited spatiotemporal resolution. In contrast, past greenhouse gas radiative forcing, causing climate to change, is well known from ice cores. We compare rates of change of anthropogenic forcing with rates of natural greenhouse gas forcing since the Last Glacial Maximum and of solar and volcanic forcing of the last millennium. The smoothing of atmospheric variations by the enclosure process of air into ice is computed with a firn diffusion and enclosure model. The 20th century increase in CO2 and its radiative forcing occurred more than an order of magnitude faster than any sustained change during the past 22,000 years. The average rate of increase in the radiative forcing not just from CO2 but from the combination of CO2, CH4, and N2O is larger during the Industrial Era than during any comparable period of at least the past 16,000 years. In addition, the decadal-to-century scale rate of change in anthropogenic forcing is unusually high in the context of the natural forcing variations (solar and volcanoes) of the past millennium. Our analysis implies that global climate change, which is anthropogenic in origin, is progressing at a speed that is unprecedented at least during the last 22,000 years. PMID:18252830

  16. Rates of change in natural and anthropogenic radiative forcing over the past 20,000 years.

    PubMed

    Joos, Fortunat; Spahni, Renato

    2008-02-05

    The rate of change of climate codetermines the global warming impacts on natural and socioeconomic systems and their capabilities to adapt. Establishing past rates of climate change from temperature proxy data remains difficult given their limited spatiotemporal resolution. In contrast, past greenhouse gas radiative forcing, causing climate to change, is well known from ice cores. We compare rates of change of anthropogenic forcing with rates of natural greenhouse gas forcing since the Last Glacial Maximum and of solar and volcanic forcing of the last millennium. The smoothing of atmospheric variations by the enclosure process of air into ice is computed with a firn diffusion and enclosure model. The 20th century increase in CO(2) and its radiative forcing occurred more than an order of magnitude faster than any sustained change during the past 22,000 years. The average rate of increase in the radiative forcing not just from CO(2) but from the combination of CO(2), CH(4), and N(2)O is larger during the Industrial Era than during any comparable period of at least the past 16,000 years. In addition, the decadal-to-century scale rate of change in anthropogenic forcing is unusually high in the context of the natural forcing variations (solar and volcanoes) of the past millennium. Our analysis implies that global climate change, which is anthropogenic in origin, is progressing at a speed that is unprecedented at least during the last 22,000 years.

  17. Grazing rates of Calanus finmarchicus on Thalassiosira weissflogii cultured under different levels of ultraviolet radiation.

    PubMed

    Fields, David M; Durif, Caroline M F; Bjelland, Reidun M; Shema, Steven D; Skiftesvik, Anne B; Browman, Howard I

    2011-01-01

    UVB alters photosynthetic rate, fatty acid profiles and morphological characteristics of phytoplankton. Copepods, important grazers of primary production, select algal cells based upon their size, morphological traits, nutritional status, and motility. We investigated the grazing rates of the copepod Calanus finmarchicus on the diatom Thalassiosira weissflogii cultured under 3 levels of ultraviolet radiation (UVR): photosynthetically active radiation (PAR) only (4 kJ-m(-2)/day), and PAR supplemented with UVR radiation at two intensities (24 kJ-m(-2)/day and 48 kJ-m(-2)/day). There was no significant difference in grazing rates between the PAR only treatment and the lower UVR treatment. However, grazing rates were significantly (∼66%) higher for copepods feeding on cells treated with the higher level of UVR. These results suggest that a short-term increase in UVR exposure results in a significant increase in the grazing rate of copepods and, thereby, potentially alters the flow rate of organic matter through this component of the ecosystem.

  18. Gamma radiation at a human relevant low dose rate is genotoxic in mice

    NASA Astrophysics Data System (ADS)

    Graupner, Anne; Eide, Dag M.; Instanes, Christine; Andersen, Jill M.; Brede, Dag A.; Dertinger, Stephen D.; Lind, Ole C.; Brandt-Kjelsen, Anicke; Bjerke, Hans; Salbu, Brit; Oughton, Deborah; Brunborg, Gunnar; Olsen, Ann K.

    2016-09-01

    Even today, 70 years after Hiroshima and accidents like in Chernobyl and Fukushima, we still have limited knowledge about the health effects of low dose rate (LDR) radiation. Despite their human relevance after occupational and accidental exposure, only few animal studies on the genotoxic effects of chronic LDR radiation have been performed. Selenium (Se) is involved in oxidative stress defence, protecting DNA and other biomolecules from reactive oxygen species (ROS). It is hypothesised that Se deficiency, as it occurs in several parts of the world, may aggravate harmful effects of ROS-inducing stressors such as ionising radiation. We performed a study in the newly established LDR-facility Figaro on the combined effects of Se deprivation and LDR γ exposure in DNA repair knockout mice (Ogg1‑/‑) and control animals (Ogg1+/‑). Genotoxic effects were seen after continuous radiation (1.4 mGy/h) for 45 days. Chromosomal damage (micronucleus), phenotypic mutations (Pig-a gene mutation of RBCCD24‑) and DNA lesions (single strand breaks/alkali labile sites) were significantly increased in blood cells of irradiated animals, covering three types of genotoxic activity. This study demonstrates that chronic LDR γ radiation is genotoxic in an exposure scenario realistic for humans, supporting the hypothesis that even LDR γ radiation may induce cancer.

  19. Gamma radiation at a human relevant low dose rate is genotoxic in mice

    PubMed Central

    Graupner, Anne; Eide, Dag M.; Instanes, Christine; Andersen, Jill M.; Brede, Dag A.; Dertinger, Stephen D.; Lind, Ole C.; Brandt-Kjelsen, Anicke; Bjerke, Hans; Salbu, Brit; Oughton, Deborah; Brunborg, Gunnar; Olsen, Ann K.

    2016-01-01

    Even today, 70 years after Hiroshima and accidents like in Chernobyl and Fukushima, we still have limited knowledge about the health effects of low dose rate (LDR) radiation. Despite their human relevance after occupational and accidental exposure, only few animal studies on the genotoxic effects of chronic LDR radiation have been performed. Selenium (Se) is involved in oxidative stress defence, protecting DNA and other biomolecules from reactive oxygen species (ROS). It is hypothesised that Se deficiency, as it occurs in several parts of the world, may aggravate harmful effects of ROS-inducing stressors such as ionising radiation. We performed a study in the newly established LDR-facility Figaro on the combined effects of Se deprivation and LDR γ exposure in DNA repair knockout mice (Ogg1−/−) and control animals (Ogg1+/−). Genotoxic effects were seen after continuous radiation (1.4 mGy/h) for 45 days. Chromosomal damage (micronucleus), phenotypic mutations (Pig-a gene mutation of RBCCD24−) and DNA lesions (single strand breaks/alkali labile sites) were significantly increased in blood cells of irradiated animals, covering three types of genotoxic activity. This study demonstrates that chronic LDR γ radiation is genotoxic in an exposure scenario realistic for humans, supporting the hypothesis that even LDR γ radiation may induce cancer. PMID:27596356

  20. Lost life expectancy rate: An application to environmental levels of radiation

    SciTech Connect

    Johnson, W.H.; Kearfott, K.J.

    1997-08-01

    The risk index Lost Life Expectancy Rate (LLER) provides a unitless number (time of life expectancy lost per time exposed) describing the risk from exposure to a given hazard or from partaking in a given activity. Simple equations to calculate the LLER from radiation-induced cancers caused by an exposure to low-level radiation were derived using the relative risk models developed by the Nuclear Regulatory Commission (upper bound estimate), the United Nations Scientific Committee on the Effects of Atomic Radiation-1988, and the National Academy of Science`s Committee on the Biological Effects of Ionizing Radiation (BEIR V). Estimates of the LLER to an average person from a continuous exposure to 0.1 {mu}Sv h{sup -1} based on these models, respectively, are 5.5 x 10{sup -4}, 9.5 x 10{sup -4}, and 9.4 x 10{sup -4}. These values compare to LLERs of 0.015 from occupational accidents, 0.25 from being an automobile passenger, and 2.0 from cigarette smoking. Factors effecting LLER from radiation exposures examined in this work include dose rate, age, sex, race and smoking status. 22 refs., 3 figs., 2 tabs.

  1. Origins of Deviations from Transition-State Theory: Formulating a New Kinetic Rate Law for Dissolution of Silicates

    SciTech Connect

    Andreas Luttge; Jonathan Icenhower

    2005-12-20

    Present models for dissolution of silicate minerals and glasses, based on Transition-State Theory (TST), overestimate the reaction rate as solution compositions approach saturation with respect to the rate-governing solid.

  2. A critical firing rate associated with tonic-to-bursting transitions in synchronized gap-junction coupled neurons

    NASA Astrophysics Data System (ADS)

    Shaffer, Annabelle; Follmann, Rosangela; Harris, Allison L.; Postnova, Svetlana; Braun, Hans; Rosa, Epaminondas

    2017-06-01

    A transition between tonic and bursting neuronal behaviors is studied using a linear chain of three electrically coupled model neurons. Numerical simulations show that, depending on their individual dynamical states, the neurons first synchronize either in a tonic or in a bursting regime. Additionally, a characteristic firing rate, mediating tonic-to-bursting transitions in networked neurons, is found to be associated with a firing rate encountered in the single neuron's equivalent transition. A few cases describing this peculiar phenomenon are presented.

  3. Using Nice-Ohvms Lineshapes to Study Relaxation Rates and Transition Dipole Moments

    NASA Astrophysics Data System (ADS)

    Hodges, James N.; McCall, Benjamin J.

    2016-06-01

    Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy (NICE-OHVMS) is a successful technique that we have developed to sensitively, precisely, and accurately record transitions of molecular ions. It has been used exclusively as a method for precise transition frequency measurement via saturation and fitting of the resultant Lamb dips. NICE-OHVMS has been employed to improve the uncertainties on H_3^+, CH_5^+, HeH^+, and OH^+, reducing the transition frequency uncertainties by two orders of magnitude. Because NICE-OHVMS is a saturation technique, this provides a unique opportunity to access information about the ratio of the transition dipole moment to the relaxation rate of the transition. This can be done in two ways, either through comparison of Lamb dip depth to the transition profile or comparison of the absorption intensity and dispersion intensity. Due to the complexity of the modulation scheme, there are many parameters that affect the apparent intensity of the recorded lineshape. A complete understanding of the lineshape is required to make the measurements of interest. Here we present a model that accounts for the heterodyne modulation and velocity modulation, assuming that the fundamental lineshape is represented by a Voigt profile. Fits to data are made and interpreted in order to extract the saturation parameter. K.N. Crabtree et al., Chem. Phys. Lett. 551, 1 (2012). J.N. Hodges et al., J. Chem. Phys. 139, 164201 (2013). A.J. Perry et al., J. Mol. Spectrosc. 317, 71 (2015). A.J. Perry et al., J. Chem. Phys. 141, 101101 (2014). C.R. Marcus et al., Astrophys. J. 817, 138 (2016).

  4. Tuning the glass transition of asphalt binder based on viscosity criteria under zero shear rates

    NASA Astrophysics Data System (ADS)

    Kwang-Hua, Chu Rainer

    2017-05-01

    With the theory of absolute reaction rate or transition-state approach together with the boundary perturbation method we calculate the possible temperature-dependent viscosity of bitumen or asphalt binder via tuning of activation volume as well as activation energy for the first time under zero shear rates. Before we present our novel approach and numerical results we firstly verify our calculations with both ambient temperature and high temperature viscosity measurements for bitumen conducted previously. Our tuning activation volume of bitumen will be useful to the current needs of intelligent compaction and application of nanotechnology to easily handling or processing asphalt binder.

  5. Radiation response of industrial materials: Dose-rate and morphology implications

    NASA Astrophysics Data System (ADS)

    Berejka, Anthony J.

    2007-08-01

    Industrial uses of ionizing radiation mostly rely upon high current, high dose-rate (100 kGy/s) electron beam (EB) accelerators. To a lesser extent, industry uses low dose-rate (2.8 × 10-3 kGy/s) radioactive Cobalt-60 as a gamma source, generally for some rather specific purposes, as medical device sterilization and the treatment of food and foodstuffs. There are nearly nine times as many (∼1400) high current EB units in commercial operation than gamma sources (∼160). However, gamma sources can be easily scaled-down so that much research on materials effects is conducted using gamma radiation. Likewise, laboratories are more likely to have very low beam current and consequently low dose-rate accelerators such as Van de Graaff generators and linear accelerators. With the advent of very high current EB accelerators, X-ray processing has become an industrially viable option. With X-rays from high power sources, dose-rates can be modulated based upon accelerator power and the attenuation of the X-ray by the distance of the material from the X-ray target. Dose and dose-rate dependence has been found to be of consequence in several commercial applications which can employ the use of ionizing radiation. The combination of dose and dose-rate dependence of the polymerization and crosslinking of wood impregnants and of fiber composite matrix materials can yield more economically viable results which have promising commercial potential. Monomer and oligomer structure also play an important role in attaining these desirable results. The influence of morphology is shown on the radiation response of olefin polymers, such as ethylene, propylene and isobutylene polymers and their copolymers. Both controlled morphology and controlled dose-rate have commercial consequences. These are also impacted both by the adroit selection of materials and through the possible use of X-ray processing.

  6. Effect of radiation dose-rate on hematopoietic cell engraftment in adult zebrafish.

    PubMed

    Glass, Tiffany J; Hui, Susanta K; Blazar, Bruce R; Lund, Troy C

    2013-01-01

    Although exceptionally high radiation dose-rates are currently attaining clinical feasibility, there have been relatively few studies reporting the biological consequences of these dose-rates in hematopoietic cell transplant (HCT). In zebrafish models of HCT, preconditioning before transplant is typically achieved through radiation alone. We report the comparison of outcomes in adult zebrafish irradiated with 20 Gy at either 25 or 800 cGy/min in the context of experimental HCT. In non-transplanted irradiated fish we observed no substantial differences between dose-rate groups as assessed by fish mortality, cell death in the kidney, endogenous hematopoietic reconstitution, or gene expression levels of p53 and ddb2 (damage-specific DNA binding protein 2) in the kidney. However, following HCT, recipients conditioned with the higher dose rate showed significantly improved donor-derived engraftment at 9 days post transplant (p ≤ 0.0001), and improved engraftment persisted at 31 days post transplant. Analysis for sdf-1a expression, as well as transplant of hematopoietic cells from cxcr4b -/- zebrafish, (odysseus), cumulatively suggest that the sdf-1a/cxcr4b axis is not required of donor-derived cells for the observed dose-rate effect on engraftment. Overall, the adult zebrafish model of HCT indicates that exceptionally high radiation dose-rates can impact HCT outcome, and offers a new system for radiobiological and mechanistic interrogation of this phenomenon. Key words: Radiation dose rate, Total Marrow Irradiation (TMI), Total body irradiation (TBI), SDF-1, Zebrafish, hematopoietic cell transplant.

  7. Transition from Ignition to Flame Growth under External Radiation in Three Dimensions (TIGER-3D)

    NASA Technical Reports Server (NTRS)

    Kashiwagi, Takashi; Nakamura, Yuji; Olson, Sandra L.; Mell, William

    2004-01-01

    This study focuses on localized ignition by external radiant flux and subsequent flame growth over thin polymeric materials (plastic and paper) in microgravity. Two transition stages were observed. The first transition stage covers the period from the onset of ignition to the formation of stabilized flame near the ignited area. This is followed by the second transition of the flame growth stage from the initial stabilized flame to sustained fire growth away from the ignited area. For the first stage, ignition experiments of thin PMMA sheets were conducted using a CO2 laser as an external source in the 10 s drop tower. The results of front side surface ignition and of backside surface ignition were observed. The effects of imposed flow velocity, sample thickness, and ambient oxygen concentration on ignition are obtained. Numerical study was conducted to investigate to understand and predict ignition behavior observed in the experiments. For the second stage, numerical study is being conducted to describe the effects of gravity on heat release rate of a PMMA sheet. The gravity level was varied from zero to normal gravity. The preliminary results show that the maximum heat release occurs at around 0.02 g.

  8. Transition from Ignition to Flame Growth under External Radiation in 3D

    NASA Technical Reports Server (NTRS)

    Kashiwagi, Takashi; Nakamura, Yuji; Mell, William E.; Olson, Sandra L.

    2004-01-01

    This study focuses on localized ignition by external radiant flux and subsequent flame growth over thin polymeric materials (plastic and paper) in microgravity. Two transition stages were observed. The first transition stage covers the period from the onset of ignition to the formation of stabilized flame near the ignited area. This is followed by the second transition of the flame growth stage from the initial stabilized flame to sustained fire growth away from the ignited area. For the first stage, ignition experiments of thin PMMA sheets were conducted using a CO2 laser as an external source in the 10 s drop tower. The results of front side surface ignition and of backside surface ignition were observed. The effects of imposed flow velocity, sample thickness, and ambient oxygen concentration on ignition are obtained. Numerical study was conducted to investigate to understand and predict ignition behavior observed in the experiments. For the second stage, numerical study is being conducted to describe the effects of gravity on heat release rate of a PMMA sheet. The gravity level was varied from zero to normal gravity. The preliminary results show that the maximum heat release occurs at around 0.02 g.

  9. Theory of molecular rate processes in the presence of intense laser radiation

    NASA Technical Reports Server (NTRS)

    George, T. F.; Zimmerman, I. H.; Devries, P. L.; Yuan, J.-M.; Lam, K.-S.; Bellum, J. C.; Lee, H.-W.; Slutsky, M. S.; Lin, J.-T.

    1979-01-01

    The present paper deals with the influence of intense laser radiation on gas-phase molecular rate processes. Representations of the radiation field, the particle system, and the interaction involving these two entities are discussed from a general rather than abstract point of view. The theoretical methods applied are outlined, and the formalism employed is illustrated by application to a variety of specific processes. Quantum mechanical and semiclassical treatments of representative atom-atom and atom-diatom collision processes in the presence of a field are examined, and examples of bound-continuum processes and heterogeneous catalysis are discussed within the framework of both quantum-mechanical and semiclassical theories.

  10. Theory of molecular rate processes in the presence of intense laser radiation

    NASA Technical Reports Server (NTRS)

    George, T. F.; Zimmerman, I. H.; Devries, P. L.; Yuan, J.-M.; Lam, K.-S.; Bellum, J. C.; Lee, H.-W.; Slutsky, M. S.; Lin, J.-T.

    1979-01-01

    The present paper deals with the influence of intense laser radiation on gas-phase molecular rate processes. Representations of the radiation field, the particle system, and the interaction involving these two entities are discussed from a general rather than abstract point of view. The theoretical methods applied are outlined, and the formalism employed is illustrated by application to a variety of specific processes. Quantum mechanical and semiclassical treatments of representative atom-atom and atom-diatom collision processes in the presence of a field are examined, and examples of bound-continuum processes and heterogeneous catalysis are discussed within the framework of both quantum-mechanical and semiclassical theories.

  11. Remote Sensing of Radiation Dose Rate by a Robot for Outdoor Usage

    NASA Astrophysics Data System (ADS)

    Kobayashi, T.; Doi, K.; Kanematsu, H.; Utsumi, Y.; Hashimoto, R.; Takashina, T.

    2013-04-01

    In the present paper, the design and prototyping of a telemetry system, in which GPS, camera, and scintillation counter were mounted on a crawler type traveling vehicle, were conducted for targeting outdoor usage such as school playground. As a result, the crawler type traveling vehicle can be operated smoothly in the school grounds of brick and asphalt. The results were as follows: (1) It was confirmed that the crawler type traveling vehicle can be operated smoothly in the school grounds of brick and asphalt (running speed: 17[m/min]). (2) It was confirmed that the location information captured by GPS is visible on the Google map, and that the incorporation of video information is also possible to play. (3)A radiation dose rate of 0.09[μSv / h] was obtained in the ground. The value is less than the 1/40 ([3.8μSv / h]) allowable radiation dose rate for children in Fukushima Prefecture.(4)As a further work, modifying to program traveling, the measurement of the distribution of the radiation dose rate in a school of Fukushima Prefecture, and class delivery on radiation measurement will be carried out.

  12. A Global Model Simulation of Aerosol Effects of Surface Radiation Budget- Toward Understanding of the "Dimming to Brightening" Transition

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Diehl, Thomas; Bian, Huisheng; Yu, Hongbin

    2008-01-01

    We present a global model study on the role aerosols play in the change of solar radiation at Earth's surface that transitioned from a decreasing (dimming) trend to an increasing (brightening) trend. Our primary objective is to understand the relationship between the long-term trends of aerosol emission, atmospheric burden, and surface solar radiation. More specifically, we use the recently compiled comprehensive global emission datasets of aerosols and precursors from fuel combustion, biomass burning, volcanic eruptions and other sources from 1980 to 2006 to simulate long-term variations of aerosol distributions and optical properties, and then calculate the multi-decadal changes of short-wave radiative fluxes at the surface and at the top of the atmosphere by coupling the GOCART model simulated aerosols with the Goddard radiative transfer model. The model results are compared with long-term observational records from ground-based networks and satellite data. We will address the following critical questions: To what extent can the observed surface solar radiation trends, known as the transition from dimming to brightening, be explained by the changes of anthropogenic and natural aerosol loading on global and regional scales? What are the relative contributions of local emission and long-range transport to the surface radiation budget and how do these contributions change with time?

  13. A Global Model Simulation of Aerosol Effects of Surface Radiation Budget- Toward Understanding of the "Dimming to Brightening" Transition

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Diehl, Thomas; Bian, Huisheng; Yu, Hongbin

    2008-01-01

    We present a global model study on the role aerosols play in the change of solar radiation at Earth's surface that transitioned from a decreasing (dimming) trend to an increasing (brightening) trend. Our primary objective is to understand the relationship between the long-term trends of aerosol emission, atmospheric burden, and surface solar radiation. More specifically, we use the recently compiled comprehensive global emission datasets of aerosols and precursors from fuel combustion, biomass burning, volcanic eruptions and other sources from 1980 to 2006 to simulate long-term variations of aerosol distributions and optical properties, and then calculate the multi-decadal changes of short-wave radiative fluxes at the surface and at the top of the atmosphere by coupling the GOCART model simulated aerosols with the Goddard radiative transfer model. The model results are compared with long-term observational records from ground-based networks and satellite data. We will address the following critical questions: To what extent can the observed surface solar radiation trends, known as the transition from dimming to brightening, be explained by the changes of anthropogenic and natural aerosol loading on global and regional scales? What are the relative contributions of local emission and long-range transport to the surface radiation budget and how do these contributions change with time?

  14. Low doses ionizing radiation enhances the invasiveness of breast cancer cells by inducing epithelial-mesenchymal transition

    SciTech Connect

    Zhang, Xin; Li, Xiaoyan; Zhang, Ning; Yang, Qifeng; Moran, Meena S.

    2011-08-19

    Highlights: {yields} Low doses ionizing irradiation would enhance the invasiveness of breast cancer cells by inducing EMT. {yields} Low doses ionizing radiation induced morphologic changes in breast cancer cells. {yields} Low doses ionizing radiation led to upregulation of mesenchymal markers and down-regulation of epithelial markers. {yields} Low doses ionizing radiation increased migration and invasion of breast cancer cells. -- Abstract: Epithelial-mesenchymal transition (EMT) is a process cellular morphologic and molecular alterations facilitate cell invasion. We hypothesized that low dose ionizing irradiation (LDIR) enhances the invasiveness of breast cancer cells by inducing EMT. The effects of LDIR on cellular morphology and the EMT markers of MCF-7 breast cancer cells were analyzed by western blot/RT-PCR and migration/invasion was examined using the transwell assay. We found that LDIR led to the phenotypic changes of EMT in MCF-7 cells and down-regulation of epithelial differentiation markers and transcriptional induction of mesenchymal markers. Furthermore, the radiated cells demonstrated enhanced migration/invasion MCF-7 cells compared with non-radiated cells. In summary, LDIR promotes the invasiveness of breast cancer cells through epithelial to mesenchymal transition. These findings may ultimately provide a new targeted approach for improving the therapeutic effectiveness of radiation in breast cancer.

  15. A Complete Set of Radiative and Auger Rates for K-vacancy States in Fe XVIII-Fe-XXV

    NASA Technical Reports Server (NTRS)

    Palmeri, P.; Mendoza, C.; Kallman, T. R.; Bautista, M. A.

    2003-01-01

    A complete set of level energies, wavelengths, A-values, and total and partial Auger rates have been computed for transitions involving the K-vacancy states within the n = 2 complex of Fe XVIII-Fe XXV. Three different standard numerical packages are used for this purpose, namel y AUTOSTRUCTURE, the Breit-Pauli R-matrix suite (BPRM) and HFR, which allow reliable estimates of the physical effects involved and of the accuracy of the resulting data sets. The Breit interaction is taken i nto account because its contributions to the small A-values and partial Auger rates cannot be neglected with increasing electron occupancy. Semiempirical adjustments can also lead to large differences in both the radiative and Auger decay data of strongly mixed levels. Several experimental level energies and wavelengths are questioned, and significant discrepancies are found with previously computed decay rates th at are attributed to numerical problems. The statistical accuracy of the present level energies and wavelengths is ranked at +/-3 eV and +/ -2 mA, respectively, and that for A-values and partial Auger rates greater than lO(exp 13)/s at better than 20%.

  16. A Complete Set of Radiative and Auger Rates for K-vacancy States in Fe XVIII-Fe XXV

    NASA Technical Reports Server (NTRS)

    Palmeri, P.; Mendoza, C.; Kallman, T. R.; Bautista, M. A.

    2002-01-01

    A complete set of level energies, wavelengths, A-values, and total and partial Auger rates have been computed for transitions involving the K-vacancy states within the n = 2 complex of Fe XVIII-Fe XXV. Three different standard numerical packages are used for this purpose, namely AUTOSTRUCTURE, the Breit-Pauli R-matrix suite (BPRM) and HFR, which allow reliable estimates of the physical effects involved and of the accuracy of the resulting data sets. It is found that the Breit interaction must be always taken into account as the contributions to the small A-values and partial Auger rates does not decrease with electron occupancy. Semi-empirical adjustments can also lead to large differences in both the radiative and Auger decay data of strongly mixed levels. Several experimental energy levels and wavelengths are questioned, and significant discrepancies are found with previously computed decay rates that are attributed to numerical problems. The statistical accuracy of the present level energies and wavelengths is ranked at plus or minus 3 eV and plus or minus 2 mAngstroms, respectively, whereas that for A-values and partial Auger rates greater than 10(exp 13) per second is estimated at better than 20%.

  17. A Complete Set of Radiative and Auger Rates for K-vacancy States in Fe XVIII-Fe-XXV

    NASA Technical Reports Server (NTRS)

    Palmeri, P.; Mendoza, C.; Kallman, T. R.; Bautista, M. A.

    2003-01-01

    A complete set of level energies, wavelengths, A-values, and total and partial Auger rates have been computed for transitions involving the K-vacancy states within the n = 2 complex of Fe XVIII-Fe XXV. Three different standard numerical packages are used for this purpose, namel y AUTOSTRUCTURE, the Breit-Pauli R-matrix suite (BPRM) and HFR, which allow reliable estimates of the physical effects involved and of the accuracy of the resulting data sets. The Breit interaction is taken i nto account because its contributions to the small A-values and partial Auger rates cannot be neglected with increasing electron occupancy. Semiempirical adjustments can also lead to large differences in both the radiative and Auger decay data of strongly mixed levels. Several experimental level energies and wavelengths are questioned, and significant discrepancies are found with previously computed decay rates th at are attributed to numerical problems. The statistical accuracy of the present level energies and wavelengths is ranked at +/-3 eV and +/ -2 mA, respectively, and that for A-values and partial Auger rates greater than lO(exp 13)/s at better than 20%.

  18. Radiation bronchitis and stenosis secondary to high dose rate endobronchial irradiation

    SciTech Connect

    Speiser, B.L. ); Spratling, L.

    1993-03-15

    The purpose of the study was to describe a new clinical entity observed in follow-up bronchoscopies in patients who were treated with high dose rate and medium dose rate remote afterloading brachytherapy of the tracheobronchial tree. Patients were treated by protocol with medium dose rate, 47 patients receiving 1000 cGy at a 5 mm depth times three fractions, high dose rate 144 patients receiving 1000 cGy at a 10 mm depth for three fractions and high dose rate 151 patients receiving cGy at a 10 mm depth for three fractions followed by bronchoscopy. Incidence of this entity was 9% for the first group, 12% for the second, and 13% for the third group. Reactions were grade 1 consisting of mild inflammatory response with a partial whitish circumferential membrane in an asymptomatic patient; grade 2, thicker complete white circumferential membrane with cough and/or obstructive problems requiring intervention; grade 3, severe inflammatory response with marked membranous exudate and mild fibrotic reaction; and grade 4 a predominant fibrotic reaction with progressive stenosis. Variables associated with a slightly increased incidence of radiation bronchitis and stenosis included: large cell carcinoma histology, curative intent, prior laser photoresection, and/or concurrent external radiation. Survival was the strongest predictor of the reaction. Radiation bronchitis and stenosis is a new clinical entity that must be identified in bronchial brachytherapy patients and treated appropriately. 23 refs., 3 figs., 7 tabs.

  19. Estimating transition rates in aggregated Markov models of ion channel gating with loops and with nearly equal dwell times

    PubMed Central

    Wagner, M.; Michalek, S.; Timmer, J.

    1999-01-01

    A typical task in the application of aggregated Markov models to ion channel data is the estimation of the transition rates between the states. Realistic models for ion channel data often have one or more loops. We show that the transition rates of a model with loops are not identifiable if the model has either equal open or closed dwell times. This non-identifiability of the transition rates also has an effect on the estimation of the transition rates for models which are not subject to the constraint of either equal open or closed dwell times. If a model with loops has nearly equal dwell times, the Hessian matrix of its likelihood function will be ill-conditioned and the standard deviations of the estimated transition rates become extraordinarily large for a number of data points which are typically recorded in experiments.

  20. Structural relaxation time and cooling rate of a melt in the glass transition region

    NASA Astrophysics Data System (ADS)

    Sanditov, D. S.; Sydykov, B. S.

    2015-03-01

    The nature of the parameter involved in the Bartenev equation qτg = C relating the cooling rate of a glass-forming melt to its structural relaxation time in the glass transition region is discussed on the basis of the Volkenshtein-Ptitsyn theory using a number of known relationships. It is established that parameter C for amorphous substances with the same fragility is linearly temperature dependent. This parameter is shown to equal the narrow temperature range δ T g characterizing the liquid-glass transition region (by Nemilov); i.e., C = δ T g. It is concluded that δ T g for most glassy systems is only ˜0.7% of the glass transition temperature T g. The narrowness of temperature range δ T g is explained by the small fluctuation volume fraction f g "frozen" at the glass transition temperature. The concept of a close relationship between constant C and the structural order at T g (i.e., the characteristic of the inner state of a nonequilibrium "frozen" amorphous system) is developed.

  1. Transitions.

    ERIC Educational Resources Information Center

    Field, David; And Others

    1992-01-01

    Includes four articles: "Career Aspirations" (Field); "Making the Transition to a New Curriculum" (Baker, Householder); "How about a 'Work to School' Transition?" (Glasberg); and "Technological Improvisation: Bringing CNC to Woodworking" (Charles, McDuffie). (SK)

  2. The Evaporation Rate and Net Radiation of white Class A Evaporation Pan

    NASA Astrophysics Data System (ADS)

    CHU, C. R.

    2015-12-01

    This study experimentally investigates the influence of color on the evaporation rate of the Class A evaporation pan. Two Class A evaporation pans, one in the original galvanized metal color and the other painted white, are placed in the same meteorological station for eighteen months. Since the wind speed, air temperature and vapor pressure deficit are the same for both pans, the color and the resulting net radiation are the only causes for the difference in the evaporation rate. The results reveal that the average net radiation of the white pan is about 90% that of the metal-colored pan. This leads to the annual evaporation rate of the white pan (1041 mm/year) being only 75% of the evaporation rate (1392 mm/year) of the metal-colored pan. In addition, the prediction error of the daily evaporation rates by the energy budget method is lower than that of the Penman-Monteith type models. The differences between the measured evaporation rates of the two pans are analyzed to examine the role of irradiance on the pan evaporation rate. The results indicate that the irradiance absorbed by the pan wall can affect the energy budget and evaporation rate of the pan.

  3. Diet and mortality rates in Sub-Saharan Africa: Stages in the nutrition transition

    PubMed Central

    2011-01-01

    Background During the last century we have seen wide-reaching changes in diet, nutritional status and life expectancy. The change in diet and physical activity patterns has become known as the nutrition transition. At any given time, a country or region within a country may be at different stages within this transition. This paper examines a range of nutrition-related indicators for countries in Sub-Saharan Africa (SSA) and attempts to develop a typical model of a country in transition. Methods Based on the availability of data, 40 countries in SSA were selected for analysis. Data were obtained from the World Health Organisation, Demographic and Health Surveys and the Food and Agriculture Organisation of the United Nations. Multiple linear regression analysis (MLRA) was used to explore the determinants of infant mortality. A six point score was developed to identify each country's stage in the nutrition transition. Results MLRA showed that underweight-for-age, protein and the percentage of exclusively breastfed infants were associated with the infant mortality rate (IMR). The majority of countries (n = 26) used in the analysis had nutrition transition scores of zero and one. Most of them had a high prevalence of infant mortality, children that were stunted or underweight-for-age, small percentages of women that were overweight and obese, and low intakes of energy, protein, and fat. Countries with the highest scores include South Africa, Ghana, Gabon, Cape Verde and Senegal which had relatively low IMRs, high levels of obesity/overweight, and low levels of underweight in women, as well as high intakes of energy and fat. These countries display classic signs of a population well established in the nutrition-related non-communicable disease phase of the nutrition transition. Conclusions Countries in SSA are clearly undergoing a nutrition transition. More than half of them are still in the early stage, while a few have reached a point where changes in dietary patterns

  4. Risk of solid cancer in low dose-rate radiation epidemiological studies and the dose-rate effectiveness factor.

    PubMed

    Shore, Roy; Walsh, Linda; Azizova, Tamara; Rühm, Werner

    2017-10-01

    Estimated radiation risks used for radiation protection purposes have been based primarily on the Life Span Study (LSS) of atomic bomb survivors who received brief exposures at high dose rates, many with high doses. Information is needed regarding radiation risks from low dose-rate (LDR) exposures to low linear-energy-transfer (low-LET) radiation. We conducted a meta-analysis of LDR epidemiologic studies that provide dose-response estimates of total solid cancer risk in adulthood in comparison to corresponding LSS risks, in order to estimate a dose rate effectiveness factor (DREF). We identified 22 LDR studies with dose-response risk estimates for solid cancer after minimizing information overlap. For each study, a parallel risk estimate was derived from the LSS risk model using matching values for sex, mean ages at first exposure and attained age, targeted cancer types, and accounting for type of dosimetric assessment. For each LDR study, a ratio of the excess relative risk per Gy (ERR Gy(-1)) to the matching LSS ERR risk estimate (LDR/LSS) was calculated, and a meta-analysis of the risk ratios was conducted. The reciprocal of the resultant risk ratio provided an estimate of the DREF. The meta-analysis showed a LDR/LSS risk ratio of 0.36 (95% confidence interval [CI] 0.14, 0.57) for the 19 studies of solid cancer mortality and 0.33 (95% CI 0.13, 0.54) when three cohorts with only incidence data also were added, implying a DREF with values around 3, but statistically compatible with 2. However, the analyses were highly dominated by the Mayak worker study. When the Mayak study was excluded the LDR/LSS risk ratios increased: 1.12 (95% CI 0.40, 1.84) for mortality and 0.54 (95% CI 0.09, 0.99) for mortality + incidence, implying a lower DREF in the range of 1-2. Meta-analyses that included only cohorts in which the mean dose was <100 mGy yielded a risk ratio of 1.06 (95% CI 0.30, 1.83) for solid cancer mortality and 0.58 (95% CI 0.10, 1.06) for mortality

  5. Meta-analysis of non-tumour doses for radiation-induced cancer on the basis of dose-rate.

    PubMed

    Tanooka, Hiroshi

    2011-07-01

    Quantitative analysis of cancer risk of ionising radiation as a function of dose-rate. Non-tumour dose, D(nt), defined as the highest dose of radiation at which no statistically significant tumour increase was observed above the control level, was analysed as a function of dose-rate of radiation. An inverse correlation was found between D(nt) and dose-rate of the radiation. D(nt) increased 20-fold with decreasing dose-rate from 1-10(-8) Gy/min for whole body irradiation with low linear energy transfer (LET) radiation. Partial body radiation also showed a dose-rate dependence with a 5- to 10-fold larger D(nt) as dose rate decreased. The dose-rate effect was also found for high LET radiation but at 10-fold lower D(nt) levels. The cancer risk of ionising radiation varies 1000-fold depending on the dose-rate of radiation and exposure conditions. This analysis explains the discrepancy of cancer risk between A-bomb survivors and radium dial painters.

  6. Ultraviolet radiation detector to obtain the rate of particles at different heights

    NASA Astrophysics Data System (ADS)

    Ponce, E.; Flores, E.; Conde, R.

    2016-10-01

    The nature and origin of cosmic rays remains one of the greatest puzzles of modern astrophysics after more than 50 years since their first registration. Several ground experiments have reported the rate registered at its height of operation. To continue with the study of cosmic rays, we propose obtain the rate at different heights in the Earth's atmosphere, developing a small and portable ultraviolet radiation detector, consisting of a scintillation plastic, a PMT, and a fast DAQ system. In this work we present the design and construction of the UV detector and the rate recorded in the Sierra Negra Volcano near Puebla, Mexico (4200 m.a.s.l).

  7. Differences in rates of decrease of environmental radiation dose rates by ground surface property in Fukushima City after the Fukushima Daiichi nuclear power plant accident.

    PubMed

    Kakamu, Takeyasu; Kanda, Hideyuki; Tsuji, Masayoshi; Kobayashi, Daisuke; Miyake, Masao; Hayakawa, Takehito; Katsuda, Shin-ichiro; Mori, Yayoi; Okouchi, Toshiyasu; Hazama, Akihiro; Fukushima, Tetsuhito

    2013-01-01

    After the Great East Japan Earthquake on 11 March 2011, the environmental radiation dose in Fukushima City increased. On 11 April, 1 mo after the earthquake, the environmental radiation dose rate at various surfaces in the same area differed greatly by surface property. Environmental radiation measurements continue in order to determine the estimated time to 50% reduction in environmental radiation dose rates by surface property in order to make suggestions for decontamination in Fukushima. The measurements were carried out from 11 April to 11 November 2011. Forty-eight (48) measurement points were selected, including four kinds of ground surface properties: grass (13), soil (5), artificial turf (7), and asphalt (23). Environmental radiation dose rate was measured at heights of 100 cm above the ground surface. Time to 50% reduction of environmental radiation dose rates was estimated for each ground surface property. Radiation dose rates on 11 November had decreased significantly compared with those on 11 April for all surface properties. Artificial turf showed the longest time to 50% reduction (544.32 d, standard error: 96.86), and soil showed the shortest (213.20 d, standard error: 35.88). The authors found the environmental radiation dose rate on artificial materials to have a longer 50% reduction time than that on natural materials. These results contribute to determining an order of priority for decontamination after nuclear disasters.

  8. Predicted Rates of Secondary Malignancies From Proton Versus Photon Radiation Therapy for Stage I Seminoma

    SciTech Connect

    Simone, Charles B.; Kramer, Kevin; O'Meara, William P.; Bekelman, Justin E.; Belard, Arnaud; McDonough, James; O'Connell, John

    2012-01-01

    Purpose: Photon radiotherapy has been the standard adjuvant treatment for stage I seminoma. Single-dose carboplatin therapy and observation have emerged as alternative options due to concerns for acute toxicities and secondary malignancies from radiation. In this institutional review board-approved study, we compared photon and proton radiotherapy for stage I seminoma and the predicted rates of excess secondary malignancies for both treatment modalities. Methods and Material: Computed tomography images from 10 consecutive patients with stage I seminoma were used to quantify dosimetric differences between photon and proton therapies. Structures reported to be at increased risk for secondary malignancies and in-field critical structures were contoured. Reported models of organ-specific radiation-induced cancer incidence rates based on organ equivalent dose were used to determine the excess absolute risk of secondary malignancies. Calculated values were compared with tumor registry reports of excess secondary malignancies among testicular cancer survivors. Results: Photon and proton plans provided comparable target volume coverage. Proton plans delivered significantly lower mean doses to all examined normal tissues, except for the kidneys. The greatest absolute reduction in mean dose was observed for the stomach (119 cGy for proton plans vs. 768 cGy for photon plans; p < 0.0001). Significantly more excess secondary cancers per 10,000 patients/year were predicted for photon radiation than for proton radiation to the stomach (4.11; 95% confidence interval [CI], 3.22-5.01), large bowel (0.81; 95% CI, 0.39-1.01), and bladder (0.03; 95% CI, 0.01-0.58), while no difference was demonstrated for radiation to the pancreas (0.02; 95% CI, -0.01-0.06). Conclusions: For patients with stage I seminoma, proton radiation therapy reduced the predicted secondary cancer risk compared with photon therapy. We predict a reduction of one additional secondary cancer for every 50 patients

  9. Transitions in genetic toggle switches driven by dynamic disorder in rate coefficients

    NASA Astrophysics Data System (ADS)

    Chen, Hang; Thill, Peter; Cao, Jianshu

    2016-05-01

    In biochemical systems, intrinsic noise may drive the system switch from one stable state to another. We investigate how kinetic switching between stable states in a bistable network is influenced by dynamic disorder, i.e., fluctuations in the rate coefficients. Using the geometric minimum action method, we first investigate the optimal transition paths and the corresponding minimum actions based on a genetic toggle switch model in which reaction coefficients draw from a discrete probability distribution. For the continuous probability distribution of the rate coefficient, we then consider two models of dynamic disorder in which reaction coefficients undergo different stochastic processes with the same stationary distribution. In one, the kinetic parameters follow a discrete Markov process and in the other they follow continuous Langevin dynamics. We find that regulation of the parameters modulating the dynamic disorder, as has been demonstrated to occur through allosteric control in bistable networks in the immune system, can be crucial in shaping the statistics of optimal transition paths, transition probabilities, and the stationary probability distribution of the network.

  10. Efficient dynamical correction of the transition state theory rate estimate for a flat energy barrier.

    PubMed

    Mökkönen, Harri; Ala-Nissila, Tapio; Jónsson, Hannes

    2016-09-07

    The recrossing correction to the transition state theory estimate of a thermal rate can be difficult to calculate when the energy barrier is flat. This problem arises, for example, in polymer escape if the polymer is long enough to stretch between the initial and final state energy wells while the polymer beads undergo diffusive motion back and forth over the barrier. We present an efficient method for evaluating the correction factor by constructing a sequence of hyperplanes starting at the transition state and calculating the probability that the system advances from one hyperplane to another towards the product. This is analogous to what is done in forward flux sampling except that there the hyperplane sequence starts at the initial state. The method is applied to the escape of polymers with up to 64 beads from a potential well. For high temperature, the results are compared with direct Langevin dynamics simulations as well as forward flux sampling and excellent agreement between the three rate estimates is found. The use of a sequence of hyperplanes in the evaluation of the recrossing correction speeds up the calculation by an order of magnitude as compared with the traditional approach. As the temperature is lowered, the direct Langevin dynamics simulations as well as the forward flux simulations become computationally too demanding, while the harmonic transition state theory estimate corrected for recrossings can be calculated without significant increase in the computational effort.

  11. Ultra-high-rate pseudocapacitive energy storage in two-dimensional transition metal carbides

    NASA Astrophysics Data System (ADS)

    Lukatskaya, Maria R.; Kota, Sankalp; Lin, Zifeng; Zhao, Meng-Qiang; Shpigel, Netanel; Levi, Mikhael D.; Halim, Joseph; Taberna, Pierre-Louis; Barsoum, Michel W.; Simon, Patrice; Gogotsi, Yury

    2017-08-01

    The use of fast surface redox storage (pseudocapacitive) mechanisms can enable devices that store much more energy than electrical double-layer capacitors (EDLCs) and, unlike batteries, can do so quite rapidly. Yet, few pseudocapacitive transition metal oxides can provide a high power capability due to their low intrinsic electronic and ionic conductivity. Here we demonstrate that two-dimensional transition metal carbides (MXenes) can operate at rates exceeding those of conventional EDLCs, but still provide higher volumetric and areal capacitance than carbon, electrically conducting polymers or transition metal oxides. We applied two distinct designs for MXene electrode architectures with improved ion accessibility to redox-active sites. A macroporous Ti3C2Tx MXene film delivered up to 210 F g‑1 at scan rates of 10 V s‑1, surpassing the best carbon supercapacitors known. In contrast, we show that MXene hydrogels are able to deliver volumetric capacitance of ∼1,500 F cm‑3 reaching the previously unmatched volumetric performance of RuO2.

  12. Excitation energies, polarizabilities, multipole transition rates, and lifetimes of ions along the francium isoelectronic sequence

    SciTech Connect

    Safronova, U. I.; Johnson, W. R.; Safronova, M. S.

    2007-10-15

    Relativistic many-body perturbation theory is applied to study properties of ions of the francium isoelectronic sequence. Specifically, energies of the 7s, 7p, 6d, and 5f states of Fr-like ions with nuclear charges Z=87-100 are calculated through third order; reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for 7s-7p, 7p-6d, and 6d-5f electric-dipole transitions; and 7s-6d, 7s-5f, and 5f{sub 5/2}-5f{sub 7/2} multipole matrix elements are evaluated to obtain the lifetimes of low-lying excited states. Moreover, for the ions Z=87-92 calculations are also carried out using the relativistic all-order single-double method, in which single and double excitations of Dirac-Fock wave functions are included to all orders in perturbation theory. With the aid of the single-double wave functions, we obtain accurate values of energies, transition rates, oscillator strengths, and the lifetimes of these six ions. Ground state scalar polarizabilities in Fr I, Ra II, Ac III, and Th IV are calculated using relativistic third-order and all-order methods. Ground state scalar polarizabilities for other Fr-like ions are calculated using a relativistic second-order method. These calculations provide a theoretical benchmark for comparison with experiment and theory.

  13. Ab initio calculations of energy levels, transition rates and lifetimes in Ni xii

    NASA Astrophysics Data System (ADS)

    Bilal, M.; Beerwerth, R.; Volotka, A. V.; Fritzsche, S.

    2017-08-01

    We report large-scale multi-configuration Dirac-Hartree-Fock calculations and relativistic configuration interaction calculations for allowed E1 and forbidden transitions (M1, E2, M2) among the fine structure levels of the 3s23p5, 3s3p6 and 3s23p43d configurations for Ni xii. In our systematically enlarged wave functions, we incorporated the effects of relativity, all important electron correlations and rearrangement of the bound electron density within two different computational models. We compare our calculated energies for the fine structure levels with previous calculations and experiments. We validate all the tentative experimental lines recently identified by Del Zanna & Badnell with one exception. We discuss the consistency of our transition rates in comparison to semi-empirical predictions. We present ab initio lifetime values by taking into account all allowed E1 and forbidden transitions (M1, E2, M2) rates among lowest 31 levels. Our results for lifetime values are better than previously reported ab initio and semi-empirical values as compared to available experiments, thus, providing reliable predictions in the prospects of future experiments.

  14. Project on the superposition of beamlines for parametric X-ray radiation and coherent transition radiation in the THz region at LEBRA

    NASA Astrophysics Data System (ADS)

    Hayakawa, Y.; Hayakawa, K.; Inagaki, M.; Kaneda, T.; Nakao, K.; Nogami, K.; Sakae, T.; Sakai, T.; Sei, N.; Takahashi, Y.; Tanaka, T.

    2016-07-01

    A new project to develop a terahertz (THz)-wave light source is in progress at the parametric X-ray (PXR) beamline of the Laboratory for Electron Beam Research and Application (LEBRA) at Nihon University. The THz-wave source is based on coherent transition radiation (CTR) emitted from a metal foil inserted downstream from a crystal target that is the PXR radiator. Beryllium or titanium foil is the most promising candidate for a THz-wave radiator. Since the electron linac of LEBRA was developed for a free electron laser (FEL), electron beam with bunch length of 1 ps (rms) can be provided by magnetic bunching at the bending magnet section. Thus, very intense coherent transition radiation (CTR) can be obtained in the frequency region around 1 THz. The results of preliminary experiments for CTR production suggested that sufficiently intense THz-CTR can be obtained using the LEBRA linac. In order to realize a THz-wave source for practical application studies, we have a plan to add the extraction feature for THz waves to the PXR beamline.

  15. VizieR Online Data Catalog: Energies & radiative transition from ArXII to ZnXXIV (Wang+, 2016)

    NASA Astrophysics Data System (ADS)

    Wang, K.; Si, R.; Dang, W.; Jonsson, P.; Guo, X. L.; Li, S.; Chen, Z. B.; Zhang, H.; Long, F. Y.; Liu, H. T.; Li, D. F.; Hutton, R.; Chen, C. Y.; Yan, J.

    2016-04-01

    Combined relativistic configuration interaction and many-body perturbation calculations are performed for the 359 fine-structure levels of the 2s22p3, 2s2p4, 2p5, 2s22p23l, 2s2p33l, 2p43l, and 2s22p24l configurations in N-like ions from Ar XII to Zn XXIV. Complete and consistent data sets of energies, wavelengths, radiative rates, oscillator strengths, and line strengths for all possible electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among the 359 levels are given for each ion. The present work significantly increases the amount of accurate data for ions in the nitrogen-like sequence, and the accuracy of the energy levels is high enough to enable the identification and interpretation of observed spectra involving the n=3, 4 levels, for which experimental values are largely scarce. Meanwhile, the results should be of great help for modeling and diagnosing astrophysical and fusion plasmas. (2 data files).

  16. Impact of gamma radiation on the eruption rate of rat incisors

    NASA Astrophysics Data System (ADS)

    El-Faramawy, Nabil; El-Haddad, Khaled; Ali, Mohamed; Talaat, Mona

    2015-09-01

    The present work aims to test the effect of gamma radiation on the rate of eruption of rat incisors. One hundred and five adult male albino rats were used and irradiated at different gamma doses. The effects of irradiation were investigated by numerical measurements of eruption rate, histological investigation using light microscope and spectral analysis using Fourier Transform Infra-Red (FTIR). No detectable changes were observed in the groups with smaller radiation doses. There was a significant decrease in the eruption rate starting from the 4 Gy radiation dose. The observation of histological sections revealed disturbance in cellular elements responsible for eruption as well as periodontal disturbance in the samples irradiated with 4 and 6 Gy. FTIR Spectroscopy of control group and the group irradiated by 0.5 Gy showed similar absorption bands with minor differences. However, samples irradiated by 1 Gy showed significant changes in both molecular structure and conformation related to carbonates and hydroxyl groups. From the previous results, it could be concluded that gamma irradiation negatively affects the eruption rate of the rat incisors especially with higher doses.

  17. Measuring radiation induced changes in the error rate of fiber optic data links

    NASA Astrophysics Data System (ADS)

    Decusatis, Casimer; Benedict, Mel

    1996-12-01

    The purpose of this work is to investigate the effects of ionizing (gamma) radiation exposure on the bit error rate (BER) of an optical fiber data communication link. While it is known that exposure to high radiation dose rates will darken optical fiber permanently, comparatively little work has been done to evaluate modern dose rates. The resulting increase in fiber attenuation over time represents an additional penalty in the link optical power budget, which can degrade the BER if it is not accounted for in the link design. Modeling the link to predict this penalty is difficult, and it requires detailed information about the fiber composition that may not be available to the link designer. We describe a laboratory method for evaluating the effects of moderate dose rates on both single-mode and multimode fiber. Once a sample of fiber has been measured, the data can be fit to a simple model for predicting (at least to first order) BER as a function of radiation dose for fibers of similar composition.

  18. Transition dipole function and radiative lifetimes for the A and C 1Σ+ states of the LiH molecule

    NASA Astrophysics Data System (ADS)

    Berriche, Hamid; Gadéa, Florent Xavier

    2016-01-01

    The transition dipole moments of the first eight 1Σ+ states of the LiH molecule have been calculated using ab initio approach based on the pseudopotential technique. Such transition dipole moments have been used to determine the radiative lifetimes for all vibrational levels of the first and the second excited states, A and C 1Σ+, using accurate adiabatic potential energy curves. In addition to the bound-bound transitions, we have included the bound-free emissions probabilities. The latter was calculated exactly and using the Franck-Condon approximation and then included in the total radiative lifetime. A significant change in these lifetimes has been observed, particularly for the higher excited vibrational levels for which the approximate evaluation breaks down. The radiative lifetimes of the vibrational levels of the A1Σ+ exited sate are in very good agreement with the few available theoretical and experimental results. However, the radiative lifetimes associated to the C1Σ+ state are presented here for the first time.

  19. A new transition radiation detector to detect heavy nuclei around the knee

    NASA Astrophysics Data System (ADS)

    Boyle, Patrick J.; Swordy, Simon P.; Wakely, Scott P.

    2003-02-01

    The overall cosmic ray intensity spectrum falls as a constant power law over at least 11 decades of particle energy. One of the only features in this spectrum is the slight change in power law index near 1015 eV, often called the ‘knee" of the spectrum. Accurate measurements of cosmic ray elemental abundances into this energy region are expected to reveal the origin of this feature, and possibly the nature of cosmic ray sources. The extremely low intensity of particles at these energies (a few per m2 per year) makes the detection challenging. Since only direct measurements have so far proved reliable for the accurate determination of elemental composition, a large-area, light weight, device is needed to achieve long exposures above the atmosphere either on high-altitude balloons or spacecraft. Here we report on a detector which uses the x-ray transition radiation yield from plastic foams to provide a response into the knee region for heavy elements. We use individual xenon-filled gas proportional tubes as detectors, combined with Amplex ASIC chip electronics for readout. The construction of this type of detector, and its implementation in the upcoming NASA CREAM 100 day high-altitude balloon payload is described. Also discussed is the calibration of the detector in an accelerator beam at CERN and a comparison with GEANT4 Monet Carlo simulations.

  20. Instantaneous electron beam emittance measurement system based on the optical transition radiation principle

    NASA Astrophysics Data System (ADS)

    Jiang, Xiao-Guo; Wang, Yuan; Zhang, Kai-Zhi; Yang, Guo-Jun; Shi, Jin-Shui; Deng, Jian-Jun; Li, Jin

    2014-01-01

    One kind of instantaneous electron beam emittance measurement system based on the optical transition radiation principle and double imaging optical method has been set up. It is mainly adopted in the test for the intense electron-beam produced by a linear induction accelerator. The system features two characteristics. The first one concerns the system synchronization signal triggered by the following edge of the main output waveform from a Blumlein switch. The synchronous precision of about 1 ns between the electron beam and the image capture time can be reached in this way so that the electron beam emittance at the desired time point can be obtained. The other advantage of the system is the ability to obtain the beam spot and beam divergence in one measurement so that the calculated result is the true beam emittance at that time, which can explain the electron beam condition. It provides to be a powerful beam diagnostic method for a 2.5 kA, 18.5 MeV, 90 ns (FWHM) electron beam pulse produced by Dragon I. The ability of the instantaneous measurement is about 3 ns and it can measure the beam emittance at any time point during one beam pulse. A series of beam emittances have been obtained for Dragon I. The typical beam spot is 9.0 mm (FWHM) in diameter and the corresponding beam divergence is about 10.5 mrad.

  1. A novel coaxial Ku-band transit radiation oscillator without external guiding magnetic field

    SciTech Connect

    Ling, Junpu Zhang, Jiande; He, Juntao; Jiang, Tao

    2014-02-15

    A novel coaxial transit radiation oscillator without external guiding magnetic field is designed to generate high power microwave at Ku-band. By using a coaxial structure, the space-charge potential energy is suppressed significantly, that is good for enhancing efficient beam-wave interaction. In order to improve the transmission stability of the unmagnetized intense relativistic electron beam, a Pierce-like cathode is employed in the novel device. By contrast with conventional relativistic microwave generators, this kind of device has the advantages of high stability, non-guiding magnetic field, and high efficiency. Moreover, with the coaxial design, it is possible to improve the power-handing capacity by increasing the radial dimension of the Ku-band device. With a 550 keV and 7.5 kA electron beam, a 1.25 GW microwave pulse at 12.08 GHz has been obtained in the simulation. The power conversion efficiency is about 30%.

  2. Detector control system for the ATLAS Transition Radiation Tracker: architecture and development techniques

    NASA Astrophysics Data System (ADS)

    Banaś, ElŻbieta; Hajduk, Zbigniew; Olszowska, Jolanta

    2012-05-01

    The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three sub-systems of the ATLAS Inner Detector at the Large Hadron Collider at CERN. With ~300000 drift tube proportional counters (straws) filled with stable gas mixture and high voltage biased it provides precise quasi-continuous tracking and particles identification. Safe, coherent and efficient operation of the TRT is fulfilled with the help of the Detector Control System (DCS) running on 11 computers as PVSS (industrial SCADA) projects. Standard industrial and custom developed server applications and protocols are used for reading hardware parameters. Higher level control system layers based on the CERN JCOP framework allow for automatic control procedures, efficient error recognition and handling and provide a synchronization mechanism with the ATLAS data acquisition system. Different data bases are used to store the detector online parameters, the configuration parameters and replicate a subset of them used to flag data quality for physics reconstruction. The TRT DCS is fully integrated with the ATLAS Detector Control System.

  3. Transition radiation model for LF radio emission produced by ultrahigh-energy cosmic rays

    NASA Astrophysics Data System (ADS)

    Rahman, M.; Boruah, K.

    2016-03-01

    Wide-band radio emission from cosmic ray-induced extensive air showers is now well established. The electromagnetic component of the extensive air shower, during their propagation through atmosphere, interacts with their surroundings emitting radio pulses which can be detected from the very low frequency to the very high frequency. Conventional detection techniques, although effective, have lower duty cycles and are expensive. The radio method, on the other hand, provides almost 100 % duty cycle after suppressing the radio frequency interferences and is also cost-effective. Correlation studies show that there must be at least two separate mechanisms responsible for radio emission at low and high frequencies. So far, theoretical models based on computer simulations have been successful in explaining the emission at high frequencies. However, at low frequencies, the available theories have been incapable of explaining the observed field strengths as high as 750 μV/m/MHz. In this paper, a mathematical model based on transition radiation is proposed to explain the low-frequency radio emission that uses realistic particle distribution obtained from the Monte Carlo simulation code CORSIKA.

  4. Theoretical considerations on imaging of micron size electron beam with optical transition radiation

    NASA Astrophysics Data System (ADS)

    Xiang, Dao; Huang, Wen-Hui

    2007-01-01

    Optical transition radiation (OTR) has been widely used to image electron beam profile. In this paper, we systematically investigated the issues related to imaging of electron beam with OTR. It is found that the point-spread function (PSF) largely depends on the acceptance angle of the lens and is only very weakly dependent on beam energy and the distance from the OTR target to the lens. This excludes the potential obstacles to imaging of high-energy electron beam for which, the photons are emitted in a relatively small cone and the far field condition is hard to fulfill. The image of a whole beam is found by convoluting the real beam distribution with the PSF. It is shown that for micron size beam, the image formed with OTR largely deviates from the real beam distribution. And the real beam distribution could be restored from deconvoluting the image with the PSF. The effectiveness of the restoration is demonstrated, which opens up the possibility of measuring micron size beam profile with OTR.

  5. Energies, radiative and Auger transitions of the core-excited states for the boron atom

    NASA Astrophysics Data System (ADS)

    Chen, Chao; Sun, Yan; Cong Gou, Bing

    2014-09-01

    Energies, radiative and Auger transitions of the 1s vacancy resonances 1s2s22p2, 1s2s22p3p, 1s2s2p3, 1s2p4, and 1s2p33p, 4L (L=S, P, D) for the neutral boron atom are calculated using the saddle-point variation and saddle-point complex-rotation methods. Large-scale wave functions are used to obtain reliable results. Relativistic and mass polarization corrections are included by the first-order perturbation theory. The calculated term energies, x-ray wavelengths, and Auger electron energies for these core-excited states are compared with available theoretical and experimental results. Auger electron energies and branching ratios are used to identify high-resolution B Auger spectrum produced in 300 keV B+ on CH4 collision experiment. It is found that the Auger decay of core-excited states of the boron atom gives significant contributions to Auger spectrum in the range of 165-210 eV, and many previously unknown line identifications are presented.

  6. Zeeman Tuning Rate for Q Branch Transitions in the v3 Band of NO2

    NASA Technical Reports Server (NTRS)

    Mahon, C. R.; Chackerian, C., Jr.; Gore, Warren J. Y. (Technical Monitor)

    1997-01-01

    Zeeman tuning rates have bee a measured for Q branch transitions in the v3 band of NO2(approx.1610/cm) for magnetic fields of up to 564 Gauss. The average measured tuning rate is 0.1815(53) x 10(exp -3)/cm/Gauss with no dependence on Ka within the approx. equal to 3% standard deviation. Despite significant ,pin-rotation interaction between several of the observed levels the result agrees with the simple linear model for Honda case (be molecules (tuning rate = 2muogs = 0.18696 x 10(exp -3)/cm/Gauss) which neglects the spin-rotation interaction between different J states. The Zeeman effect is analyzed in a full treatment of the Hamiltonian, including spin-rotation interaction, in order to account for the agreement with 2muogs and to explore the onset of spin-rotation effects in the spectra as the magnetic field is increased.

  7. Zeeman Tuning Rates for Q-Branch Transitions in the nu3 Band of NO2

    PubMed

    Mahon; Chackerian

    1998-06-01

    Zeeman tuning rates have been measured for Q-branch transitions in the nu3 band of NO2 ( approximately 1610 cm-1) for magnetic fields of up to 564 Gauss. The average measured tuning rate is 0.1815(53) x 10(-3) cm-1/Gauss with no dependence on Ka within the approximately 3% standard deviation. Despite significant spin-rotation interaction between several of the observed levels the result agrees with the simple linear model for Hunds case (b) molecules (tuning rate = 2µogs = 0.18696 x 10(-3) cm-1/G), which neglects the spin-rotation interaction between different J states. The Zeeman effect is analyzed in a full treatment of the Hamiltonian, including spin-rotation interaction, in order to account for the agreement with 2µogs and to explore the onset of spin-rotation effects in the spectra as the magnetic field is increased. Copyright 1998 Academic Press.

  8. Chloroquine Improves Survival and Hematopoietic Recovery After Lethal Low-Dose-Rate Radiation

    SciTech Connect

    Lim Yiting; Hedayati, Mohammad; Merchant, Akil A.; Zhang Yonggang; Yu, Hsiang-Hsuan M.; Kastan, Michael B.; Matsui, William; DeWeese, Theodore L.

    2012-11-01

    Purpose: We have previously shown that the antimalarial agent chloroquine can abrogate the lethal cellular effects of low-dose-rate (LDR) radiation in vitro, most likely by activating the ataxia-telangiectasia mutated (ATM) protein. Here, we demonstrate that chloroquine treatment also protects against lethal doses of LDR radiation in vivo. Methods and Materials: C57BL/6 mice were irradiated with a total of 12.8 Gy delivered at 9.4 cGy/hour. ATM null mice from the same background were used to determine the influence of ATM. Chloroquine was administered by two intraperitoneal injections of 59.4 {mu}g per 17 g of body weight, 24 hours and 4 hours before irradiation. Bone marrow cells isolated from tibia, fibula, and vertebral bones were transplanted into lethally irradiated CD45 congenic recipient mice by retroorbital injection. Chimerism was assessed by flow cytometry. In vitro methylcellulose colony-forming assay of whole bone marrow cells and fluorescence activated cell sorting analysis of lineage depleted cells were used to assess the effect of chloroquine on progenitor cells. Results: Mice pretreated with chloroquine before radiation exhibited a significantly higher survival rate than did mice treated with radiation alone (80% vs. 31%, p = 0.0026). Chloroquine administration before radiation did not affect the survival of ATM null mice (p = 0.86). Chloroquine also had a significant effect on the early engraftment of bone marrow cells from the irradiated donor mice 6 weeks after transplantation (4.2% vs. 0.4%, p = 0.015). Conclusion: Chloroquine administration before radiation had a significant effect on the survival of normal but not ATM null mice, strongly suggesting that the in vivo effect, like the in vitro effect, is also ATM dependent. Chloroquine improved the early engraftment of bone marrow cells from LDR-irradiated mice, presumably by protecting the progenitor cells from radiation injury. Chloroquine thus could serve as a very useful drug for protection

  9. Chloroquine improves survival and hematopoietic recovery following lethal low dose- rate radiation

    PubMed Central

    Lim, Yiting; Hedayati, Mohammad; Merchant, Akil A.; Zhang, Yonggang; Yu, Hsiang-Hsuan M; Kastan, Michael B.; Matsui, William; DeWeese, Theodore L.

    2012-01-01

    Purpose We have previously shown that the anti-malarial agent chloroquine can abrogate the lethal cellular effects of low dose-rate (LDR) radiation in vitro, most likely by activating the ataxia-telangiectasia mutated (ATM) protein. Here, we demonstrate that chloroquine treatment also protects against lethal doses of LDR radiation in vivo. Methods and Materials C57BL/6 mice were irradiated with total of 12.8 Gy delivered at 9.4 cGy/hr. ATM null mice from the same background were used to determine the influence of ATM. Chloroquine was administered by two intraperitoneal injections of 59.4 μg per 17 g of body weight, 24 hrs and 4 hrs before irradiation. Bone marrow cells isolated from tibia, fibula and vertebral bones were transplanted into lethally irradiated CD45 congenic recipient mice by retro orbital injection. Chimerism was assessed by flow cytometry. In vitro methyl cellulose colony forming assay of whole bone marrow cells as well as FACS analysis of lineage depleted cells was used to assess the effect of chloroquine on progenitor cells. Results Mice pretreated with chloroquine prior to radiation exhibited a significantly higher survival rate compared to mice treated with radiation alone (80 vs.31 percent, p=0.0026). Chloroquine administration prior to radiation did not impact the survival of ATM null mice (p=0.86). Chloroquine also had a significant effect on the early engraftment of bone marrow cells from the irradiated donor mice 6 weeks after the transplantation (4.2 percent vs. 0.4 percent, p=0.015). Conclusion Chloroquine administration prior to radiation had a significant effect on the survival of normal but not ATM null mice strongly suggesting that the in vivo effect like the in vitro effect is also ATM dependent. Chloroquine improved the early engraftment of bone marrow cells from LDR irradiated mice, presumably by protecting the progenitor cells from radiation injury. Chloroquine thus could serve as a very useful drug for protection against the

  10. Biological impact of low dose-rate simulated solar particle event radiation in vivo.

    PubMed

    Chang, P Y; Doppalapudi, R; Bakke, J; Wang, A; Menda, S; Davis, Z

    2010-08-01

    C57Bl6-lacZ animals were exposed to a range of low dose-rate simulated solar particle event (sSPE) radiation at the NASA-sponsored Research Laboratory (NSRL) at Brookhaven National Laboratory (BNL). Peripheral blood was harvested from animals from 1 to 12 days after total body irradiation (TBI) to quantify the level of circulating reticulocytes (RET) and micronucleated reticulocytes (MN-RET) as an early indicator of radiation-induced genotoxicity. Bone marrow lymphocytes and hippocampal tissues from each animal were collected at 12 days and up to two months, to evaluate dose-dependent late effects after sSPE exposure. Early hematopoietic changes show that the % RET was reduced up to 3 days in response to radiation exposure but recovered at 12 days postirradiation. The % MN-RET in peripheral blood was temporally regulated and dependant on the total accumulated dose. Total chromosome aberrations in lymphocytes increased linearly with dose within a week after radiation and remained significantly higher than the control values at 4 weeks after exposure. The level of aberrations in the irradiated animals returned to control levels by 8 weeks postirradiation. Measurements of chromosome 2 and 8 specific aberrations indicate that, consistent with conventional giemsa-staining methods, the level of aberrations is also not significantly higher than in control animals at 8 weeks postirradiation. The hippocampus was surveyed for differential transcriptional regulation of genes known to be associated with neurogenesis. Our results showed differential expression of neurotrophin and their associated receptor genes within 1 week after sSPE exposure. Progressive changes in the profile of expressed genes known to be involved in neurogenic signaling pathways were dependent on the sSPE dose. Our results to date suggest that radiation-induced changes in the hematopoietic system, i.e., chromosome aberrations in lymphocytes, are transient and do not persist past 4 weeks after radiation

  11. Monte Carlo calculation of artificial radionuclide radiation dose rates for marine species in the Western Pacific.

    PubMed

    Su, Jian; Yu, Wen; Zeng, Zhi; Ma, Hao; Chen, Liqi; Cheng, Jianping

    2014-03-01

    After the Fukushima nuclear accident, there is a widespread concern over the radioactive contamination of the marine environment. To protect non-human species, a radiation dose rate calculation model for Western Pacific marine species was established. Ten kinds of marine species in the Western Pacific were modelled by Geant4 for Monte Carlo simulation. Organisms were modelled with two ellipsoids: one represented organs and the other represented muscle. The enhanced dose rates by 10 main kinds of nuclides were calculated. According to the reported activities of three main nuclides ((134)Cs, (137)Cs and (131)I) in seawater near Fukushima coastal, the radiation risks of marine species were estimated. The results showed that the marine species near the Fukushima accident drain outlets might be at risk. But organisms that were >15 km away from the drain outlets were relatively safe.

  12. Rate coefficient of CN formation through radiative association: a theoretical study of quantum effects.

    PubMed

    Antipov, Sergey V; Sjölander, Tobias; Nyman, Gunnar; Gustafsson, Magnus

    2009-08-21

    Radiative association of CN is simulated using a quantum dynamical as well as a semiclassical approach. A comparison of the resulting energy-resolved cross sections reveals striking quantum effects that are due to shape resonances. These, in turn, arise because of states that are quasibound by the centrifugal barrier. The quantal rate coefficient for temperatures from 40 to 1900 K has been computed using the Breit-Wigner theory to account for the resonances. Comparison with the results obtained by Singh and Andreazza [Astrophys. J. 537, 261 (2000)] shows that the semiclassical method, which completely omits the shape resonances, is accurate to within 25% above room temperature. At lower temperatures the contribution from the shape resonances to the radiative association rate is more significant.

  13. The mass transfer rate in X1916-053 - It is driven by gravitational radiation?

    NASA Technical Reports Server (NTRS)

    Swank, J. H.; Taam, R. E.; White, N. E.

    1985-01-01

    A 50-minute period for a binary system harboring an X-ray burster would allow several alternatives for the mass-giving secondary, including an H-shell burning-plus-He degenerate core composite model. The burst properties of X1916-053 are presently used to argue against the He degenerate as well as the He main sequence solutions and to estimate whether, for any of the other solutions, the mass transfer rate could be consistent with that expected from gravitational radiation (GR). Within an uncertainty of a factor of 2, the transfer rate for the composite model solution is consistent with gravitational radiation, but enhancement by other mechanisms should be investigated.

  14. β+ Gamow-Teller transition strengths from 46Ti and stellar electron-capture rates.

    PubMed

    Noji, S; Zegers, R G T; Austin, Sam M; Baugher, T; Bazin, D; Brown, B A; Campbell, C M; Cole, A L; Doster, H J; Gade, A; Guess, C J; Gupta, S; Hitt, G W; Langer, C; Lipschutz, S; Lunderberg, E; Meharchand, R; Meisel, Z; Perdikakis, G; Pereira, J; Recchia, F; Schatz, H; Scott, M; Stroberg, S R; Sullivan, C; Valdez, L; Walz, C; Weisshaar, D; Williams, S J; Wimmer, K

    2014-06-27

    The Gamow-Teller strength in the β(+) direction to (46)Sc was extracted via the (46)Ti(t,(3)He + γ) reaction at 115  MeV/u. The γ-ray coincidences served to precisely measure the very weak Gamow-Teller transition to a final state at 991 keV. Although this transition is weak, it is crucial for accurately estimating electron-capture rates in astrophysical scenarios with relatively low stellar densities and temperatures, such as presupernova stellar evolution. Shell-model calculations with different effective interactions in the pf shell-model space do not reproduce the experimental Gamow-Teller strengths, which is likely due to sd-shell admixtures. Calculations in the quasiparticle random phase approximation that are often used in astrophysical simulations also fail to reproduce the experimental Gamow-Teller strength distribution, leading to strongly overestimated electron-capture rates. Because reliable theoretical predictions of Gamow-Teller strengths are important for providing astrophysical electron-capture reaction rates for a broad set of nuclei in the lower pf shell, we conclude that further theoretical improvements are required to match astrophysical needs.

  15. Rate-dependent phase transitions in Li2FeSiO4 cathode nanocrystals

    PubMed Central

    Lu, Xia; Wei, Huijing; Chiu, Hsien-Chieh; Gauvin, Raynald; Hovington, Pierre; Guerfi, Abdelbast; Zaghib, Karim; Demopoulos, George P.

    2015-01-01

    Nanostructured lithium metal orthosilicate materials hold a lot of promise as next generation cathodes but their full potential realization is hampered by complex crystal and electrochemical behavior. In this work Li2FeSiO4 crystals are synthesized using organic-assisted precipitation method. By varying the annealing temperature different structures are obtained, namely the monoclinic phase at 400°C, the orthorhombic phase at 900°C, and a mixed phase at 700°C. The three Li2FeSiO4 crystal phases exhibit totally different charge/discharge profiles upon delithiation/lithiation. Thus the 400°C monoclinic nanocrystals exhibit initially one Li extraction via typical solid solution reaction, while the 900°C orthorhombic crystals are characterized by unacceptably high cell polarization. In the meantime the mixed phase Li2FeSiO4 crystals reveal a mixed cycling profile. We have found that the monoclinic nanocrystals undergo phase transition to orthorhombic structure resulting in significant progressive deterioration of the material's Li storage capability. By contrast, we discovered when the monoclinic nanocrystals are cycled initially at higher rate (C/20) and subsequently subjected to low rate (C/50) cycling the material's intercalation performance is stabilized. The discovered rate-dependent electrochemically-induced phase transition and stabilization of lithium metal silicate structure provides a novel and potentially rewarding avenue towards the development of high capacity Li-ion cathodes. PMID:25715655

  16. β+ Gamow-Teller Transition Strengths from Ti46 and Stellar Electron-Capture Rates

    NASA Astrophysics Data System (ADS)

    Noji, S.; Zegers, R. G. T.; Austin, Sam M.; Baugher, T.; Bazin, D.; Brown, B. A.; Campbell, C. M.; Cole, A. L.; Doster, H. J.; Gade, A.; Guess, C. J.; Gupta, S.; Hitt, G. W.; Langer, C.; Lipschutz, S.; Lunderberg, E.; Meharchand, R.; Meisel, Z.; Perdikakis, G.; Pereira, J.; Recchia, F.; Schatz, H.; Scott, M.; Stroberg, S. R.; Sullivan, C.; Valdez, L.; Walz, C.; Weisshaar, D.; Williams, S. J.; Wimmer, K.

    2014-06-01

    The Gamow-Teller strength in the β+ direction to Sc46 was extracted via the Ti46(t ,He3+γ) reaction at 115 MeV /u. The γ-ray coincidences served to precisely measure the very weak Gamow-Teller transition to a final state at 991 keV. Although this transition is weak, it is crucial for accurately estimating electron-capture rates in astrophysical scenarios with relatively low stellar densities and temperatures, such as presupernova stellar evolution. Shell-model calculations with different effective interactions in the pf shell-model space do not reproduce the experimental Gamow-Teller strengths, which is likely due to sd-shell admixtures. Calculations in the quasiparticle random phase approximation that are often used in astrophysical simulations also fail to reproduce the experimental Gamow-Teller strength distribution, leading to strongly overestimated electron-capture rates. Because reliable theoretical predictions of Gamow-Teller strengths are important for providing astrophysical electron-capture reaction rates for a broad set of nuclei in the lower pf shell, we conclude that further theoretical improvements are required to match astrophysical needs.

  17. Self-similar characteristics of the currency exchange rate in an economy in transition

    NASA Astrophysics Data System (ADS)

    Scarlat, E. I.; Stan, Cristina; Cristescu, C. P.

    2007-06-01

    In this paper, we present an analysis of the self-similar characteristics of the temporal series describing the daily exchange rate of the Romanian currency unit “Leu” (ROL) with respect to the US Dollar (USD). The relevance of this investigation consists in the exchange rate being a proper indicator for the dynamics of an economy in transition from a command-type structure towards an open market one. The time series is exhibiting self-similar cells of dimensions obeying a definite power law scaling rule that is related to different categories of economic agents. By using a crossing-type analysis based on the Hurst exponent and the frequency spectrum, five categories were detected. A simple model based on active filters with prevailing feedforward loops working close to the unstable regime, each one describing an economic agent under the stress of a hostile economic environment, is proposed for the dynamics of the fragmentation-defragmentation process. The model qualitatively reproduces the self-similarity characteristics of the currency exchange rate of an economy in transition, subjected to deep structural changes. We observe that the “in-phase evolution” of the economic agents causes the statistical self-similarity to resemble a theoretical self-similarity.

  18. Evaluation of radiative heating rate profiles in eight GCMs using A-train satellite observations

    NASA Astrophysics Data System (ADS)

    Cesana, Gregory; Waliser, D. E.; L'Ecuyer, T.; Jiang, X.; Li, J.-L.

    2017-02-01

    In this study, we take advantage of two modeling experiments and A-train satellite observations to characterize the impact of cloud biases in the vertical distribution of radiative heating rates in eight general circulation models General Circulation Models (GCMs). We compare the modeled vertical distribution of clouds against the GCM-Oriented Cloud-Aerosols Lidar and Infrared Pathfinder Satellite Observations Cloud Product (CALIPSO-GOCCP) using a simulator approach. Although the overall pattern of modeled zonal cloud frequency profiles is relatively good (r=0.92 for the multi-model mean), we show two main systematic biases in the cloud frequency profiles: a positive bias above 7km (up to 10%), particularly in the tropics; and a negative bias below 3km (up to -10%), which reaches a maximum over the stratocumulus cloud regions. Using radiative heating rate profiles calculated with constraints from CloudSat, CALIPSO and other satellite observations, we show that the excess of clouds in the upper troposphere (>7km) results in excess infrared and solar heating in the vicinity of the clouds as well as more infrared heating for the entire column below the cloud. On the other hand, the lack of clouds in the lower troposphere reduces the infrared cooling near the missing cloud levels and increases the absorption of solar radiation by water vapor below. The global radiative heating rate between 50°S and 50°N is too warm in the models (-0.81K/day vs. -1.01K/day). The representation of clouds in GCMs remains challenging, but reducing the cloud biases would lead to an improvement of the heating rate profiles, which in turn would help in improving other aspects of models' simulations such as the dynamics, cloud feedbacks and surface-atmosphere interactions.

  19. Emesis as a Screening Diagnostic for Low Dose Rate (LDR) Total Body Radiation Exposure

    PubMed Central

    Camarata, A. S.; Switchenko, J. M.; Demidenko, E.; Flood, A. B.; Swartz, H. M.; Ali, A. N.

    2015-01-01

    Current radiation disaster manuals list the time-to-emesis (TE) as the key triage indicator of radiation dose. The data used to support TE recommendations were derived primarily from nearly instantaneous, high dose rate exposures as part of variable condition accident databases. To date, there has not been a systematic differentiation between triage dose estimates associated with high and low dose rate (LDR) exposures, even though it is likely that after a nuclear detonation or radiologic disaster, many surviving casualties would have received a significant portion of their total exposure from fallout (LDR exposure) rather than from the initial nuclear detonation or criticality event (high dose rate exposure). This commentary discusses the issues surrounding the use of emesis as a screening diagnostic for radiation dose after LDR exposure. As part of this discussion, previously published clinical data on emesis after LDR total body irradiation (TBI) is statistically re-analyzed as an illustration of the complexity of the issue and confounding factors. This previously published data includes 107 patients who underwent TBI up to 10.5 Gy in a single fraction delivered over several hours at 0.02 to 0.04 Gy/min. Estimates based on these data for the sensitivity of emesis as a screening diagnostic for low dose rate radiation exposure range from 57.1% to 76.6%, and the estimates for specificity range from 87.5% to 99.4%. Though the original data contain multiple confounding factors, the evidence regarding sensitivity suggests that emesis appears to be quite poor as a medical screening diagnostic for LDR exposures. PMID:26910032

  20. Vibrational levels of the transition state and rate of dissociation of triplet acetaldehyde

    NASA Astrophysics Data System (ADS)

    Leu, Gen-Hou; Huang, Cheng-Liang; Lee, Shih-Huang; Lee, Yu-Chang; Chen, I.-Chia

    1998-12-01

    Fluorescence decay of the S1 state of d4-acetaldehyde is measured. Below the dissociation threshold for formation of fragments of formyl and methyl radicals, single exponential decays of fluorescence are observed. Biexponential decay is observed when the excitation energies are near and above the dissociation threshold. Hence, in this region the mechanism for intramolecular relaxation of energy reaches the "intermediate case." Strong coupling between S1 and T1 states or reversible reaction for S1↔T1 results in this biexponential behavior in the fluorescence decay of S1. Rates of appearance of DCO from dissociation of acetaldehyde are measured. The stepwise increases in plots of both rate of appearance of formyl radicals and rate of decay of excited acetaldehyde versus excitation energy for both isotopic variants of acetaldehyde are observed. According to fits to Rice-Ramsperger-Kassel-Marcus (RRKM) theory, these sharp increases correspond to vibrational levels of transition state in the triplet surface. Frequencies of torsional and C-C-O bending modes are determined to be (73±10) and (200±10) cm-1 for the transition state of CD3CDO and the torsional frequency (80±10) cm-1 for CH3CHO. That these fitted frequencies are less than values calculated with methods B3LYP and MP2 indicates a looser transition state than calculated for dissociation. From these fits the dissociation threshold for formation of radical fragments is determined to be 31 845 for CD3CDO and 31 650 cm-1 for CH3CHO.

  1. Dose-rate dependent stochastic effects in radiation cell-survival models.

    PubMed

    Sachs, R K; Hlatky, L R

    1990-01-01

    When cells are subjected to ionizing radiation the specific energy rate (microscopic analog of dose-rate) varies from cell to cell. Within one cell, this rate fluctuates during the course of time; a crossing of a sensitive cellular site by a high energy charged particle produces many ionizations almost simultaneously, but during the interval between events no ionizations occur. In any cell-survival model one can incorporate the effect of such fluctuations without changing the basic biological assumptions. Using stochastic differential equations and Monte Carlo methods to take into account stochastic effects we calculated the dose-survival relationships in a number of current cell survival models. Some of the models assume quadratic misrepair; others assume saturable repair enzyme systems. It was found that a significant effect of random fluctuations is to decrease the theoretically predicted amount of dose-rate sparing. In the limit of low dose-rates neglecting the stochastic nature of specific energy rates often leads to qualitatively misleading results by overestimating the surviving fraction drastically. In the opposite limit of acute irradiation, analyzing the fluctuations in rates merely amounts to analyzing fluctuations in total specific energy via the usual microdosimetric specific energy distribution function, and neglecting fluctuations usually underestimates the surviving fraction. The MOnte Carlo methods interpolate systematically between the low dose-rate and high dose-rate limits. As in other approaches, the slope of the survival curve at low dose-rates is virtually independent of dose and equals the initial slope of the survival curve for acute radiation.

  2. Single-cycle Terahertz Pulses with >0.2 V/A Field Amplitudes via Coherent Transition Radiation

    SciTech Connect

    Daranciang, Dan; Goodfellow, John; Fuchs, Matthias; Wen, Haidan; Ghimire, Shambhu; Reis, David A.; Loos, Henrik; Fisher, Alan S.; Lindenberg, Aaron M.; /Stanford U. Materials Sci. Dept. /SIMES, Stanford /SLAC, PULSE

    2012-02-15

    We demonstrate terahertz pulses with field amplitudes exceeding 0.2 V/{angstrom} generated by coherent transition radiation. Femtosecond, relativistic electron bunches generated at the Linac Coherent Light Source are passed through a beryllium foil, and the emitted radiation is characterized as a function of the bunch duration and charge. Broadband pulses centered at a frequency of 10 THz with energies of 140 {mu}J are measured. These far-below-bandgap pulses drive a nonlinear optical response in a silicon photodiode, with which we perform nonlinear autocorrelations that yield information regarding the terahertz temporal profile. Simulations of the spatiotemporal profile agree well with experimental results.

  3. Transition rate and the photoelectric effect in the presence of a minimal length

    NASA Astrophysics Data System (ADS)

    Khosropour, Behrooz

    2017-01-01

    In this work, according to the generalized uncertainty principle (GUP) and time-dependent perturbation theory, the transition rate in the present of a minimal length based on the Kempf algebra is studied. Also, we find the absorption cross section in the framework of the GUP. The modified photoelectric effect is investigated and we show that the differential cross section of the photoelectric effect in the framework of the GUP is related to the isotropic minimal length scale. The upper bound on the isotropic minimal length is estimated.

  4. Radiative decay rate of excitons in square quantum wells: Microscopic modeling and experiment

    SciTech Connect

    Khramtsov, E. S.; Grigoryev, P. S.; Ignatiev, I. V.; Verbin, S. Yu.; Belov, P. A. Efimov, Yu. P.; Eliseev, S. A.; Lovtcius, V. A.; Petrov, V. V.; Yakovlev, S. L.

    2016-05-14

    The binding energy and the corresponding wave function of excitons in GaAs-based finite square quantum wells (QWs) are calculated by the direct numerical solution of the three-dimensional Schrödinger equation. The precise results for the lowest exciton state are obtained by the Hamiltonian discretization using the high-order finite-difference scheme. The microscopic calculations are compared with the results obtained by the standard variational approach. The exciton binding energies found by two methods coincide within 0.1 meV for the wide range of QW widths. The radiative decay rate is calculated for QWs of various widths using the exciton wave functions obtained by direct and variational methods. The radiative decay rates are confronted with the experimental data measured for high-quality GaAs/AlGaAs and InGaAs/GaAs QW heterostructures grown by molecular beam epitaxy. The calculated and measured values are in good agreement, though slight differences with earlier calculations of the radiative decay rate are observed.

  5. Ensemble Monte Carlo calculation of the hole initiated impact ionization rate in bulk GaAs and silicon using a k-dependent, numerical transition rate formulation

    NASA Technical Reports Server (NTRS)

    Oguzman, Ismail H.; Wang, Yang; Kolnik, Jan; Brennan, Kevin F.

    1995-01-01

    The hole initiated impact ionization rate in bulk silicon and GaAs is calculated using a numerical formulation of the impact ionization transition rate incorporated into an ensemble Monte Carlo simulation. The transition rate is calculated from Fermi's golden rule using a two-body screened Coulomb interaction including a wavevector dependent dielectric function. It is found that the effective threshold for hole initiated ionization is relatively soft in both materials, that the split-off band dominates the ionization process in GaAs. and that no clear dominance by any one band is observed in silicon, though the rate out of the light hole band is greatest.

  6. Rates of E1, E2, M1, and M2 transitions in Ni II

    NASA Astrophysics Data System (ADS)

    Cassidy, C. M.; Hibbert, A.; Ramsbottom, C. A.

    2016-03-01

    Aims: We present rates for all E1, E2, M1, and M2 transitions among the 295 fine-structure levels of the configurations 3d9, 3d84s, 3d74s2, 3d84p, and 3d74s4p, determined through an extensive configuration interaction calculation. Methods: The CIV3 code developed by Hibbert and coworkers is used to determine for these levels configuration interaction wave functions with relativistic effects introduced through the Breit-Pauli approximation. Results: Two different sets of calculations have been undertaken with different 3d and 4d functions to ascertain the effect of such variation. The main body of the text includes a representative selection of data, chosen so that key points can be discussed. Some analysis to assess the accuracy of the present data has been undertaken, including comparison with earlier calculations and the more limited range of experimental determinations. The full set of transition data is given in the supplementary material as it is very extensive. Conclusions: We believe that the present transition data are the best currently available. Full Table 4 and Tables 5-8 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A107

  7. The dose rate effect with radiation processing of water—an interpretative approach

    NASA Astrophysics Data System (ADS)

    Gehringer, Peter; Eschweiler, Helmut

    2002-11-01

    Hydrogen peroxide, nitrous oxide and oxygen as well were added before irradiation to tap water contaminated with trace amounts of perchloroethylene (PCE) to study their impact to the existing dose rate effect recorded with radiation-induced PCE decomposition. Hydrogen peroxide and oxygen addition as well had almost no effect at all to PCE decomposition; addition of nitrous oxide resulted in some improvement but one order of magnitude less than adequate ozone addition brought about. At present there is no alternative for ozone to eliminate the disadvantage caused by the dose rate effect.

  8. Radiative transitions involving the (2p2)(3 Pe) metastable autodetaching of H(-)

    NASA Technical Reports Server (NTRS)

    Jacobs, V. L.; Bhatia, A. K.; Temkin, A.

    1974-01-01

    The absorption coefficient for the free-bound transition H (ls) + e(-)+ h omega yields H(-)(2 sq p,(3)P(e)) is calculated (together with the differential emission rate for the inverse process) using ls - 2s - 2p close coupling continuum wave functions and a Hylleraas bound state wave function. A maximum in the absorption and emission spectra is found to occur at a photon wavelength of 1219.5 A, which is 2 A closer to the Lyman alpha line than predicted by the calculations of Drake, and is in closer agreement with the stellar absorption feature identified by Heap and Stecher. The free-bound absorption process appears to be a significant source of continuous ultraviolet opacity.

  9. Optimal Body Temperature in Transitional ELBW Infants Using Heart Rate and Temperature as Indicators

    PubMed Central

    Knobel, Robin B.; Holditch-Davis, Diane; Schwartz, Todd A.

    2013-01-01

    Extremely low birth weight (ELBW) infants are vulnerable to cold stress after birth. Therefore, caregivers need to control body temperature optimally to minimize energy expenditure. Objective We explored body temperature in relationship to heart rate in ELBW infants during their first 12 hours to help identify the ideal set point for incubator control of body temperature. Design Within subject, multiple-case design. Setting A tertiary NICU in North Carolina. Participants 10 infants, born less than 29 weeks gestation and weighing 400-1000 grams. Methods Heart rate and abdominal body temperature were measured at 1-minute intervals for 12 hours. Heart rates were considered normal if they were between the 25th and 75th percentile for each infant. Results Abdominal temperatures were low throughout the 12-hour study period (mean 35.17° C-36.68° C). Seven of ten infants had significant correlations between abdominal temperature and heart rate. Heart rates above the 75th percentile were associated with low and high abdominal temperatures; heart rates less than the 25th percentile were associated with very low abdominal temperatures. The extent to which abdominal temperature was abnormally low was related the extent to which the heart rate trended away from normal in six of the ten infants. Optimal temperature control point that maximized normal heart rate observations for each infant was between 36.8° C and 37° C. Conclusions Hypothermia was associated with abnormal heart rates in transitional ELBW infants. We suggest nurses set incubator servo between 36.8° C and 36.9° C to optimally control body temperature for ELBW infants. PMID:20409098

  10. Conditionally-Sampled Turbulent and Nonturbulent Measurements of Entropy Generation Rate in the Transition Region of Boundary Layers

    SciTech Connect

    D. M. McEligot; J. R. Wolf; K. P. Nolan; E. J. Walsh; R. J. Volino

    2006-05-01

    Conditionally-sampled boundary layer data for an accelerating transitional boundary layer have been analyzed to calculate the entropy generation rate in the transition region. By weighing the nondimensional dissipation coefficient for the laminar-conditioned-data and turbulent-conditioned-data with the intermittency factor the average entropy generation rate in the transition region can be determined and hence be compared to the time averaged data and correlations for steady laminar and turbulent flows. It is demonstrated that this method provides, for the first time, an accurate and detailed picture of the entropy generation rate during transition. The data used in this paper have been taken from detailed boundary layer measurements available in the literature. This paper provides, using an intermittency weighted approach, a methodology for predicting entropy generation in a transitional boundary layer.

  11. Dose rate effects in radiation degradation of polymer-based cable materials

    NASA Astrophysics Data System (ADS)

    Plaček, V.; Bartoníček, B.; Hnát, V.; Otáhal, B.

    2003-08-01

    Cable ageing under the nuclear power plant (NPP) conditions must be effectively managed to ensure that the required plant safety and reliability are maintained throughout the plant service life. Ionizing radiation is one of the main stressors causing age-related degradation of polymer-based cable materials in air. For a given absorbed dose, radiation-induced damage to a polymer in air environment usually depends on the dose rate of the exposure. In this work, the effect of dose rate on the degradation rate has been studied. Three types of NPP cables (with jacket/insulation combinations PVC/PVC, PVC/PE, XPE/XPE) were irradiated at room temperature using 60Co gamma ray source at average dose rates of 7, 30 and 100 Gy/h with the doses up to 590 kGy. The irradiated samples have been tested for their mechanical properties, thermo-oxidative stability (using differential scanning calorimetry, DSC), and density. In the case of PVC and PE samples, the tested properties have shown evident dose rate effects, while the XPE material has shown no noticeable ones. The values of elongation at break and the thermo-oxidative stability decrease with the advanced degradation, density tends to increase with the absorbed dose. For XPE samples this effect can be partially explained by the increase of crystallinity. It was tested by the DSC determination of the crystalline phase amount.

  12. Equatorial Pacific Reactive Phosphorus Accumulation Rates across the Eocene/Oligocene Transition

    NASA Astrophysics Data System (ADS)

    Faul, K. L.; Stewart, K. L.

    2007-12-01

    Paired benthic foraminiferal stable isotope and trace metal records from ODP Site 1218 in the equatorial Pacific have shown that the Eocence/Oligocene (E/O) transition (~34 Ma) represents a major increase in Antarctic ice accumulation and a rapid deepening of the global calcite compensation depth (CCD) occurring in two steps [e.g., Lear et al., 2000; Lear et al., 2004; Coxall et al., 2005; Palike et al., 2006]. Simultaneous increases in biogenic mass accumulation rates (MARs) around Australia and in the Atlantic Ocean have been interpreted as representing increased productivity and/or organic carbon (C) burial possibly linked to cooling and ice sheet growth [Diester-Hass and Zahn, 2001; Anderson and Delaney, 2005]. Because the global CCD deepens across the transition, there is a need to distinguish organic C burial changes from CCD changes. We are determining reactive phosphorus (P, micromol P cm-2 kyr-1) MARs as an indicator of organic C burial for Site 1218 to help constrain the relative role of productivity during the E/O climatic transition. Reactive phosphorus (the sum of oxide associated, authigenic, and organic P; sequentially extracted from bulk sediment), delivered to the sediment water interface with organic C, is well preserved in oxygenated sediments. Preliminary results show an order of magnitude decrease in reactive P concentrations (from ~100 to ~10 micromol P g-1) across the E/O boundary. This may indicate that absolute organic C burial as well as the ratio of organic C burial to calcite burial may have decreased across the E/O transition in the equatorial Pacific upwelling zone.

  13. Modeling of transient ionizing radiation effects in bipolar devices at high dose-rates

    SciTech Connect

    FJELDLY,T.A.; DENG,Y.; SHUR,M.S.; HJALMARSON,HAROLD P.; MUYSHONDT,ARNOLDO

    2000-04-25

    -n junctions was developed by Isaque et al. They used a more complete ambipolar transport equation, which included the dependencies of the transport parameters (ambipolar diffusion constant, mobility, and recombination rate) on the excess minority carrier concentration. The expression used for the recombination rate was that of Shockley-Reed-Hall (SRH) recombination which is dominant for low to mid-level radiation intensities. However, at higher intensities, Auger recombination becomes important eventually dominant. The complete ambipolar transport equation including the complicated dependence of transport parameters on the radiation intensity, cannot be solved analytically. This solution is obtained for each of the regimes where a given recombination mechanism dominates, and then by joining these solutions using appropriate smoothing functions. This approach allows them to develop a BJT model accounting for the photoelectric effect of the ionizing radiation that can be implemented in SPICE.

  14. Radiative energy balance of Venus: An approach to parameterize thermal cooling and solar heating rates

    NASA Astrophysics Data System (ADS)

    Haus, R.; Kappel, D.; Arnold, G.

    2017-03-01

    Thermal cooling rates QC and solar heating rates QH in the atmosphere of Venus at altitudes between 0 and 100 km are investigated using the radiative transfer and radiative balance simulation techniques described by Haus et al. (2015b, 2016). QC strongly responds to temperature profile and cloud parameter changes, while QH is less sensitive to these parameters. The latter mainly depends on solar insolation conditions and the unknown UV absorber distribution. A parameterization approach is developed that permits a fast and reliable calculation of temperature change rates Q for different atmospheric model parameters and that can be applied in General Circulation Models to investigate atmospheric dynamics. A separation of temperature, cloud parameter, and unknown UV absorber influences is performed. The temperature response parameterization relies on a specific altitude and latitude-dependent cloud model. It is based on an algorithm that characterizes Q responses to a broad range of temperature perturbations at each level of the atmosphere using the Venus International Reference Atmosphere (VIRA) as basis temperature model. The cloud response parameterization considers different temperature conditions and a range of individual cloud mode factors that additionally change cloud optical depths as determined by the initial latitude-dependent model. A QH response parameterization for abundance changes of the unknown UV absorber is also included. Deviations between accurate calculation and parameterization results are in the order of a few tenths of K/day at altitudes below 90 km. The parameterization approach is used to investigate atmospheric radiative equilibrium (RE) conditions. Polar mesospheric RE temperatures above the cloud top are up to 70 K lower and equatorial temperatures up to 10 K higher than observed values. This radiative forcing field is balanced by dynamical processes that maintain the observed thermal structure.

  15. New method of proportional counter feedback biasing for wide-range radiation dose-rate monitors

    SciTech Connect

    Kopp, M.K.; Valentine, K.H.; Guerrant, G.C.; Manning, F.W.

    1984-01-01

    A prototypic wide-range radiation dose-rate monitor for civil defense applications has been developed and tested. The specified dose-rate range (0 to 500 R/h) was displayed on a single readout scale by using feedback-controlled biasing of a proportional counter. This new method is based on controlling the avalanche multiplication factor (gas gain) of the counter by varying its bias voltage in response to its measured output current (i.e., detected dose rate). The counter output current varies between 0 and 1.5 nA in a quasi-logarithmic response to dose rates between 0 and 500 R/h. The corresponding values of gas gain and bias voltage range from 1 to 300 and 200 to 1900 V respectively.

  16. High-Dose-Rate Intraoperative Radiation Therapy for Recurrent Head-and-Neck Cancer

    SciTech Connect

    Perry, David J.; Chan, Kelvin; Wolden, Suzanne; Zelefsky, Michael J.; Chiu, Johnny; Cohen, Gilad; Zaider, Marco; Kraus, Dennis; Shah, Jatin; Lee, Nancy

    2010-03-15

    Purpose: To report the use of high-dose-rate intraoperative radiation therapy (HDR-IORT) for recurrent head-and-neck cancer (HNC) at a single institution. Methods and Materials: Between July 1998 and February 2007, 34 patients with recurrent HNC received 38 HDR-IORT treatments using a Harrison-Anderson-Mick applicator with Iridium-192. A single fraction (median, 15 Gy; range, 10-20 Gy) was delivered intraoperatively after surgical resection to the region considered at risk for close or positive margins. In all patients, the target region was previously treated with external beam radiation therapy (median dose, 63 Gy; range, 24-74 Gy). The 1- and 2-year estimates for in-field local progression-free survival (LPFS), locoregional progression-free survival (LRPFS), distant metastases-free survival (DMFS), and overall survival (OS) were calculated. Results: With a median follow-up for surviving patients of 23 months (range, 6-54 months), 8 patients (24%) are alive and without evidence of disease. The 1- and 2-year LPFS rates are 66% and 56%, respectively, with 13 (34%) in-field recurrences. The 1- and 2-year DMFS rates are 81% and 62%, respectively, with 10 patients (29%) developing distant failure. The 1- and 2-year OS rates are 73% and 55%, respectively, with a median time to OS of 24 months. Severe complications included cellulitis (5 patients), fistula or wound complications (3 patients), osteoradionecrosis (1 patient), and radiation-induced trigeminal neuralgia (1 patient). Conclusions: HDR-IORT has shown encouraging local control outcomes in patients with recurrent HNC with acceptable rates of treatment-related morbidity. Longer follow-up with a larger cohort of patients is needed to fully assess the benefit of this procedure.

  17. Effects of low sampling rate in the digital data-transition tracking loop

    NASA Technical Reports Server (NTRS)

    Mileant, A.; Million, S.; Hinedi, S.

    1994-01-01

    This article describes the performance of the all-digital data-transition tracking loop (DTTL) with coherent and noncoherent sampling using nonlinear theory. The effects of few samples per symbol and of noncommensurate sampling and symbol rates are addressed and analyzed. Their impact on the probability density and variance of the phase error are quantified through computer simulations. It is shown that the performance of the all-digital DTTL approaches its analog counterpart when the sampling and symbol rates are noncommensurate (i.e., the number of samples per symbol is an irrational number). The loop signal-to-noise ratio (SNR) (inverse of phase error variance) degrades when the number of samples per symbol is an odd integer but degrades even further for even integers.

  18. Transition.

    ERIC Educational Resources Information Center

    Thompson, Sandy, Ed.; And Others

    1990-01-01

    This "feature issue" focuses on transition from school to adult life for persons with disabilities. Included are "success stories," brief program descriptions, and a list of resources. Individual articles include the following titles and authors: "Transition: An Energizing Concept" (Paul Bates); "Transition…

  19. High count-rate study of two TES x-ray microcalorimeters with different transition temperatures

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Jun; Adams, Joseph S.; Bandler, Simon R.; Betancourt-Martinez, Gabriele L.; Chervenak, James A.; Eckart, Megan E.; Finkbeiner, Fred M.; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, Frederick S.; Sadleir, John E.; Smith, Stephen J.; Wassell, Edward J.

    2017-10-01

    We have developed transition-edge sensor (TES) microcalorimeter arrays with high count-rate capability and high energy resolution to carry out x-ray imaging spectroscopy observations of various astronomical sources and the Sun. We have studied the dependence of the energy resolution and throughput (fraction of processed pulses) on the count rate for such microcalorimeters with two different transition temperatures (T c). Devices with both transition temperatures were fabricated within a single microcalorimeter array directly on top of a solid substrate where the thermal conductance of the microcalorimeter is dependent upon the thermal boundary resistance between the TES sensor and the dielectric substrate beneath. Because the thermal boundary resistance is highly temperature dependent, the two types of device with different T cs had very different thermal decay times, approximately one order of magnitude different. In our earlier report, we achieved energy resolutions of 1.6 and 2.3 eV at 6 keV from lower and higher T c devices, respectively, using a standard analysis method based on optimal filtering in the low flux limit. We have now measured the same devices at elevated x-ray fluxes ranging from 50 Hz to 1000 Hz per pixel. In the high flux limit, however, the standard optimal filtering scheme nearly breaks down because of x-ray pile-up. To achieve the highest possible energy resolution for a fixed throughput, we have developed an analysis scheme based on the so-called event grade method. Using the new analysis scheme, we achieved 5.0 eV FWHM with 96% throughput for 6 keV x-rays of 1025 Hz per pixel with the higher T c (faster) device, and 5.8 eV FWHM with 97% throughput with the lower T c (slower) device at 722 Hz.

  20. Measuring the Transition Rates of Coalescence Events during Double Phase Separation in Microgravity.

    PubMed

    Oprisan, Ana; Garrabos, Yves; Lecoutre, Carole; Beysens, Daniel

    2017-07-06

    Phase transition is a ubiquitous phenomenon in nature, science and technology. In general, the phase separation from a homogeneous phase depends on the depth of the temperature quench into the two-phase region. Earth's gravity masks the details of phase separation phenomena, which is why experiments were performed under weightlessness. Under such conditions, the pure fluid sulphur hexafluoride (SF 6 ) near its critical point also benefits from the universality of phase separation behavior and critical slowing down of dynamics. Initially, the fluid was slightly below its critical temperature with the liquid matrix separated from the vapor phase. A 0.2 mK temperature quench further cooled down the fluid and produced a double phase separation with liquid droplets inside the vapor phase and vapor bubbles inside the liquid matrix, respectively. The liquid droplets and the vapor bubbles respective distributions were well fitted by a lognormal function. The evolution of discrete bins of different radii allowed the derivation of the transition rates for coalescence processes. Based on the largest transition rates, two main coalescence mechanisms were identified: (1) asymmetric coalescences between one small droplet of about 20 μ m and a wide range of larger droplets; and (2) symmetric coalescences between droplets of large and similar radii. Both mechanisms lead to a continuous decline of the fraction of small radii droplets and an increase in the fraction of the large radii droplets. Similar coalescence mechanisms were observed for vapor bubbles. However, the mean radii of liquid droplets exhibits a t 1 / 3 evolution, whereas the mean radii of the vapor bubbles exhibit a t 1 / 2 evolution.