Secondary Electron Yield on Cryogenic Surfaces as a Function of Physisorbed Gases

CERN Document Server

Kuzucan, Asena; Taborelli, Mauro

2011-01-01

In LHC the electron cloud induced by photoelectrons, gas ionization and secondary electrons emitted from the beam pipe walls could be a limitation of the performance. The electron cloud induce heat load on the cryogenic system, cause pressure rise, emittance growth and beam instabilities, which in the end will limit the beam’s lifetime. Beam- induced multipacting, which can arise through oscillatory motion of photoelectrons and low-energy secondary electrons bouncing back and forth between opposite walls of the vacuum chamber during successive passage of proton bunches, represent therefore a potential problem for the machine. The secondary electron yield (SEY) is one of the key parameters for the electron cloud build up and multipacting phenomenon. An electron cloud occurs if the metal surface secondary electron yield is high enough for electron multiplication. This parameter has been extensively studied on room temperature samples but uncertainties remain for samples at cryogenic temperature. Indeed, at l...

Comparison of breeding methods for forage yield in red clover

Directory of Open Access Journals (Sweden)

Libor Jalůvka

2009-01-01

Full Text Available Three methods of red clover (Trifolium pratense L. breeding for forage yield in two harvest years on locations in Bredelokke (Denmark, Hladké Životice (Czech Republic and Les Alleuds (France were compared. Three types of 46 candivars1, developed by A recurrent selection in subsequent generations (37 candivars, divided into early and late group, B polycross progenies (4 candivars and C ge­no-phe­no­ty­pic selection (5 candivars were compared. The trials were sown in 2005 and cut three times in 2006 and 2007; their evaluation is based primarily on total yield of dry matter. The candivars developed by polycross and geno-phenotypic selections gave significantly higher yields than candivars from the recurrent selection. However, the candivars developed by the methods B and C did not differ significantly. The candivars developed by these progressive methods were suitable for higher yielding and drier environment in Hladké Životice (where was the highest yield level even if averaged annual precipitation were lower by 73 and 113 mm in comparison to other locations, respectively; here was ave­ra­ge yield higher by 19 and 13% for B and C in comparison to A method. Highly significant interaction of the candivars with locations was found. It can be concluded that varieties specifically aimed to different locations by the methods B and C should be bred; also the parental entries should be selected there.

Neutron yield and induced radioactivity: a study of 235-MeV proton and 3-GeV electron accelerators

International Nuclear Information System (INIS)

Hsu, Yung-Cheng; Lai, Bo-Lun; Sheu, Rong-Jiun

2016-01-01

This study evaluated the magnitude of potential neutron yield and induced radioactivity of two new accelerators in Taiwan: a 235-MeV proton cyclotron for radiation therapy and a 3-GeV electron synchrotron serving as the injector for the Taiwan Photon Source. From a nuclear interaction point of view, neutron production from targets bombarded with high-energy particles is intrinsically related to the resulting target activation. Two multi-particle interaction and transport codes, FLUKA and MCNPX, were used in this study. To ensure prediction quality, much effort was devoted to the associated benchmark calculations. Comparisons of the accelerators' results for three target materials (copper, stainless steel and tissue) are presented. Although the proton-induced neutron yields were higher than those induced by electrons, the maximal neutron production rates of both accelerators were comparable according to their respective beam outputs during typical operation. Activation products in the targets of the two accelerators were unexpectedly similar because the primary reaction channels for proton- and electron-induced activation are (p,pn) and (γ,n), respectively. The resulting residual activities and remnant dose rates as a function of time were examined and discussed. (authors)

Neutron yield of medical electron accelerators

International Nuclear Information System (INIS)

McCall, R.C.

1988-01-01

Shielding calculations for medical electron accelerators above about 10 MeV require some knowledge of the neutron emission from the machine. This knowledge might come from the manufacturer's specifications or from published measurements of the neutron leakage of that particular model and energy of accelerator. In principle, the yield can be calculated if details of the accelerator design are known. These details are often not available because the manufacturer considers them proprietary. A broader knowledge of neutron emission would be useful and it is the purpose of this paper to present such information

Neutron yield from thick lead target by the action of high-energy electrons

International Nuclear Information System (INIS)

Noga, V.I.; Ranyuk, Yu.N.; Telegin, Yu.N.; Sorokin, P.V.

1978-01-01

The results are presented of studying the complete neutron yield from a lead target bombarded by high-energy electrons. Neutrons were recorded by the method of radio-active indicators. The dependence of the neutron yield on the target thickness varying from 0.2 to 8 cm was obtained at the energies of electrons of 230 and 1200 MeV. The neutron yield for the given energies with the target of 6 cm in thickness is in the range of saturation and is 0.1 +-0.03 and 0.65+-0.22 (neutr./MeV.el.), respectively. The neutron angular distributions were measured for different thicknesses of targets at the 201, 230 and 1200 MeV electrons. Within the error limits the angular distributions are isotropic. The dependence of neutron yield on the electron energy was examined for a 3 cm thick target. In the energy range of 100-1200 MeV these values are related by a linear dependence with the proportionality coefficient C=3x10 -4 (neutr./MeV.el.)

Engineered Surfaces to Control Secondary Electron Yield for Multipactor Suppression

Science.gov (United States)

2017-09-14

Air Force Institute of Technology AFIT Scholar Theses and Dissertations 9-14-2017 Engineered Surfaces to Control Secondary Electron Yield for...Multipactor Suppression James M. Sattler Follow this and additional works at: https://scholar.afit.edu/etd Part of the Electrical and Electronics Commons... TECHNOLOGY Wright-Patterson Air Force Base, Ohio DISTRIBUTION STATEMENT A. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED

A comparison of experiment, CEPXS/ONETRAN, TIGERP, and TIGER net electron emission coefficients for various bremsstrahlung spectra

International Nuclear Information System (INIS)

Ballard, W.P.; Lorence, L.J. Jr.; Snowden, D.P.; Van Lint, V.A.J.; Beale, E.S.

1987-01-01

This work compares a carefully designed experiment to measure photoemission with the predictions of three different codes (CEPXS/ONETRAN, TIGERP, and TIGER) for the complex bremsstrahlung spectra typical of very intense pulsed power x-ray generators. The Monte Carlo codes TIGER and TIGERP can calculate the net photon-induced electron emission but accurate results may require that statistical error be minimized. CEPXS/ONETRAN is a new deterministic coupled electron/photon transport code that is faster than Monte Carlo and is not subject to statistical error. The comparison of net yields is a sensitive test of the relative accuracy and efficiency of these various codes. The authors find that all of the codes substantially agree with the experiments for the forward net yields. However, for reverse net yields from high-Z materials, the codes overpredict relative to measurements

Neutron yield and induced radioactivity: a study of 235-MeV proton and 3-GeV electron accelerators.

Science.gov (United States)

Hsu, Yung-Cheng; Lai, Bo-Lun; Sheu, Rong-Jiun

2016-01-01

This study evaluated the magnitude of potential neutron yield and induced radioactivity of two new accelerators in Taiwan: a 235-MeV proton cyclotron for radiation therapy and a 3-GeV electron synchrotron serving as the injector for the Taiwan Photon Source. From a nuclear interaction point of view, neutron production from targets bombarded with high-energy particles is intrinsically related to the resulting target activation. Two multi-particle interaction and transport codes, FLUKA and MCNPX, were used in this study. To ensure prediction quality, much effort was devoted to the associated benchmark calculations. Comparisons of the accelerators' results for three target materials (copper, stainless steel and tissue) are presented. Although the proton-induced neutron yields were higher than those induced by electrons, the maximal neutron production rates of both accelerators were comparable according to their respective beam outputs during typical operation. Activation products in the targets of the two accelerators were unexpectedly similar because the primary reaction channels for proton- and electron-induced activation are (p,pn) and (γ,n), respectively. The resulting residual activities and remnant dose rates as a function of time were examined and discussed. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A Comparison of Machine Learning Approaches for Corn Yield Estimation

Science.gov (United States)

Kim, N.; Lee, Y. W.

2017-12-01

Machine learning is an efficient empirical method for classification and prediction, and it is another approach to crop yield estimation. The objective of this study is to estimate corn yield in the Midwestern United States by employing the machine learning approaches such as the support vector machine (SVM), random forest (RF), and deep neural networks (DNN), and to perform the comprehensive comparison for their results. We constructed the database using satellite images from MODIS, the climate data of PRISM climate group, and GLDAS soil moisture data. In addition, to examine the seasonal sensitivities of corn yields, two period groups were set up: May to September (MJJAS) and July and August (JA). In overall, the DNN showed the highest accuracies in term of the correlation coefficient for the two period groups. The differences between our predictions and USDA yield statistics were about 10-11 %.

Lactation yield: Interval level comparison of milk records for genetic ...

African Journals Online (AJOL)

1220 records ... Lactation yield: Interval level comparison of milk records for genetic improvement in Friesian vs Arsi crossbred cows in the highlands of south eastern. Ethiopia. Dumar Wabe1 and Kassahun Asmare2. 1Allage Agricultural Technical, Vocational Education Training College, P.O. Box 077. 2School of Veterinary ...

Comparison of the methods for determination of scintillation light yield

CERN Document Server

Sysoeva, E; Zelenskaya, O

2002-01-01

One of the most important characteristics of scintillators is the light yield. It depends not only on the properties of scintillators, but also on the conditions of measurements. Even for widely used crystals, such as alkali halide scintillators NaI(Tl) and CsI(Tl), light yield data, obtained by various authors, are different. Therefore, it is very important to choose the convenient method of the light yield measurements. In the present work, methods for the determination of the physical light yield, based on measurements of pulse amplitude, single-electron pulses and intrinsic photomultiplier resolution are discussed. These methods have been used for the measurements of light yield of alkali halide crystals and oxide scintillators. Repeatability and reproducibility of results were determined. All these methods are rather complicated in use, not for measurements, but for further data processing. Besides that, they demand a precise determination of photoreceiver's parameters, as well as determination of light ...

Simulation of Electron-Cloud Build-Up for the Cold Arcs of the LHC and Comparison with Measured Data

CERN Document Server

Maury Cuna, H; Rumolo, G; Tavian, L; Zimmermann, F

2011-01-01

The electron cloud generated by synchrotron radiation or residual gas ionization is a concern for LHC operation and performance. We report the results of simulations studies which examine the electron cloud build-up, at injection energy, 3.5 TeV for various operation parameters. In particular, we determine the value of the secondary emission yield corresponding to the multipacting threshold, and investigate the electron density, and heat as a function of bunch intensity for dipoles and field-free regions. We also include a comparison between simulations results and measured heat-load data from the LHC scrubbing runs in 2011.

Secondary electron emission yield on poled silica based thick films

DEFF Research Database (Denmark)

Braga, D.; Poumellec, B.; Cannas, V.

2004-01-01

Studies on the distribution of the electric field produced by a thermal poling process in a layer of Ge-doped silica on silicon substrate, by using secondary electron emission yield (SEEY) measurements () are presented. Comparing 0 between poled and unpoled areas, the SEEY at the origin of electr...

A comparison of experiment, CEPXS/ONETRAN, TIGERP, and QUICKE2 net electron emission coefficients for various bremsstrahlung spectra

International Nuclear Information System (INIS)

Ballard, W.P.; Lorence, L.J. Jr.; Snowden, D.P.; van Lint, V.A.J.; Beale, E.S.

1987-01-01

This work compares a carefully designed experiment with the predictions of four different codes (CEPXS/ONETRAN, TIGERP, TIGER and QUICKE2) for the complex bremsstrahlung spectra typical of very intense pulsed power x-ray generators. Accurate calculation of net photon-induced electron emission yields at material interfaces using Monte Carlo codes can be particularly difficult if the forward and reverse partial yields are of similar magnitudes. In such a circumstance, the statistical error in the Monte Carlo solution (TIGER or TIGERP) must be kept to a minimum to accurately resolve the difference. CEPXS/ONETRAN is a new deterministic coupled electron/photon transport code that is faster than Monte Carlo and is not subject to statistical error. QUICKE2 evaluates an analytical approximation and is also much less expensive to run than the Monte Carlo codes. The comparison of net yields is a sensitive test of the relative accuracy and efficiency of these various codes. We find that all of the codes except QUICKE2 substantially agree with the experiments for the forward net yields. Howver, for reverse net yields from high-Z materials, all the codes overpredict relative to measurements

Calculation of the total electron excitation cross section in the Born approximation using Slater wave functions for the Li (2s yields 2p), Li (2s yields 3p), Na (3s yields 4p), Mg (3p yields 4s), Ca (4s yields 4p) and K (4s yields 4p) excitations. M.S. Thesis

Science.gov (United States)

Simsic, P. L.

1974-01-01

Excitation of neutral atoms by inelastic scattering of incident electrons in gaseous nebulae were investigated using Slater Wave functions to describe the initial and final states of the atom. Total cross sections using the Born Approximation are calculated for: Li(2s yields 2p), Na(3s yields 4p), k(4s yields 4p). The intensity of emitted radiation from gaseous nebulae is also calculated, and Maxwell distribution is employed to average the kinetic energy of electrons.

Yield estimation based on calculated comparisons to particle velocity data recorded at low stress

International Nuclear Information System (INIS)

Rambo, J.

1993-01-01

This paper deals with the problem of optimizing the yield estimation process if some of the material properties are known from geophysical measurements and others are inferred from in-situ dynamic measurements. The material models and 2-D simulations of the event are combined to determine the yield. Other methods of yield determination from peak particle velocity data have mostly been based on comparisons of nearby events in similar media at NTS. These methods are largely empirical and are subject to additional error when a new event has different properties than the population being used for a basis of comparison. The effect of material variations can be examined using LLNL's KDYNA computer code. The data from an NTS event provide the instructive example for simulation

Electron mobility and saturation of ion yield in 2,2,4,4-tetramethylpentane

International Nuclear Information System (INIS)

Poffenberger, P.R.; Astbury, A.; Fincke-Keeler, M.; Keeler, R.K.; Li, Y.; Robertson, L.P.; Rosvick, M.; Schenk, P.; Oram, C.; Sobie, R.

1993-01-01

The electron drift mobility μ and zero field free ion yield G fi 0 have been measured for liquid 2,2,4,4-tetramethylpentane using a waveform analysis. The saturation of the ion yield for highly ionizing radiation has also been investigated and parameterized using the Birks' equation. The results obtained are μ=26.3±0.8 cm 2 /V s, G fi 0 =0.743±0.029 electrons/100 eV, and a Birks' factor ranging from kB=0.222±0.014 cm/MeV at 604 V/cm to kB=0.141±0.021 cm/MeV at 3625 V/cm. (orig.)

Measurements of inner-shell characteristic X-ray yields of thick W, Mo and Zr targets by low-energy electron impact and comparison with Monte Carlo simulations

International Nuclear Information System (INIS)

Li, X.L.; Zhao, J.L.; Tian, L.X.; An, Z.; Zhu, J.J.; Liu, M.T.

2014-01-01

Highlights: •We measured characteristic X-ray yields of thick W, Mo, Zr by 5–29 keV electrons. •Our measured data are in general in good agreement with the MC results with ∼10%. •Error of 10% of characteristic X-ray yields will produce errors of 2–7% for BIXS. -- Abstract: Inner-shell characteristic X-ray yields are one of the important ingredients in the β-ray induced X-ray spectrometry (BIXS) technique which can be used to perform tritium content and depth distribution analyses in plasma facing materials (PLMs) and other tritium-containing materials, such as W, Mo, Zr. In this paper, the measurements of K, L, M-shell X-ray yields Y(E) of pure thick W (Z = 74), Mo (Z = 42) and Zr (Z = 40) element targets produced by electron impact in the energy range of 5–29 keV are presented. The experimental data for Y(E) are compared with the corresponding predictions from Monte Carlo (MC) calculations using the general purpose MC code PENELOPE. In general, a good agreement is obtained between the experiment and the MC calculations for the variation of Y(E) with the impact energy both in shape and in magnitude with ∼10%. The effect of uncertainty of inner-shell characteristic X-ray yields on the BIXS technique is also discussed

Comparison of Smoke Yield Data Collected from Different Laboratories

Directory of Open Access Journals (Sweden)

Teillet B

2014-12-01

Full Text Available In the context of increasing tobacco product regulations, more requirements are observed for the reporting of smoke constituent yield data and its variability e.g., US Food and Drug Administration (FDA. The objective of this work was to evaluate the relevance of the short term standard deviation to describe the variability of measurements using the dataset of the CORESTA 2006 Joint Experiment which included a number of cigarette smoke constituents more recently identified by FDA for reporting. Their testing protocol required the analysis of Kentucky Reference cigarettes 2R4F and 1R5F performing five replicates run over consecutive days, repeated during three different time periods. This dataset provided access to different sources of smoke yield variability across measurements: short term and medium term within-laboratory variability and among-laboratory variability. For each reference cigarette, analysis of variance on one factor (laboratory combined with the Newman-Keuls multiple range test was performed to compare data generated across laboratories. Results showed that the expression of yield variability as an individual standard deviation (describing repeatability gives erroneous conclusions due to the major contribution of amonglaboratory variability not being taken into account. The different sources of variability can be taken into account in the comparison using the critical difference, as described in the ISO Standard 5725 part 6. This paper shows the importance of having i the appropriate statistical methods to compare results from different laboratories in order to avoid erroneous conclusions, and ii validated and standardized methods with known precision across laboratories. Moreover, it was demonstrated that the number of replicates had only a minor effect on product comparison on the basis of the critical difference as a function of repeatability and reproducibility of the methods.

An analytical model of nonproportional scintillator light yield in terms of recombination rates

International Nuclear Information System (INIS)

Bizarri, G.; Moses, W. W.; Singh, J.; Vasil'ev, A. N.; Williams, R. T.

2009-01-01

Analytical expressions for the local light yield as a function of the local deposited energy (-dE/dx) and total scintillation yield integrated over the track of an electron of initial energy E are derived from radiative and/or nonradiative rates of first through third order in density of electronic excitations. The model is formulated in terms of rate constants, some of which can be determined independently from time-resolved spectroscopy and others estimated from measured light yield efficiency as a constraint assumed to apply in each kinetic order. The rates and parameters are used in the theory to calculate scintillation yield versus primary electron energy for comparison to published experimental results on four scintillators. Influence of the track radius on the yield is also discussed. Results are found to be qualitatively consistent with the observed scintillation light yield. The theory can be applied to any scintillator if the rates of the radiative and nonradiative processes are known

Electron beam irradiation enhances the digestibility and fermentation yield of water-soaked lignocellulosic biomass

Directory of Open Access Journals (Sweden)

Jin Seop Bak

2014-12-01

Full Text Available In order to overcome the limitation of commercial electron beam irradiation (EBI, lignocellulosic rice straw (RS was pretreated using water soaking-based electron beam irradiation (WEBI. This environment-friendly pretreatment, without the formation (or release of inhibitory compounds (especially hydroxymethylfurfural and furfural, significantly increased the enzymatic hydrolysis and fermentation yields of RS. Specifically, when water-soaked RS (solid:liquid ratio of 100% was treated with WEBI doses of 1 MeV at 80 kGy, 0.12 mA, the glucose yield after 120 h of hydrolysis was 70.4% of the theoretical maximum. This value was predominantly higher than the 29.5% and 52.1% measured from untreated and EBI-treated RS, respectively. Furthermore, after simultaneous saccharification and fermentation for 48 h, the ethanol concentration, production yield, and productivity were 9.3 g/L, 57.0% of the theoretical maximum, and 0.19 g/L h, respectively. Finally, scanning electron microscopy images revealed that WEBI induced significant ultrastructural changes to the surface of lignocellulosic fibers.

Mean secondary electron yield of avalanche electrons in the channels of a microchannel plate detector

International Nuclear Information System (INIS)

Funsten, H.O.; Suszcynsky, D.M.; Harper, R.W.

1996-01-01

By modeling the statistical evolution of an avalanche created by 20 keV protons impacting the input surface of a z-stack microchannel plate (MCP) detector, the mean secondary electron yield γ C of avalanche electrons propagating through a MCP channel is measured to equal 1.37 for 760 V per MCP in the z stack. This value agrees with other studies that used MCP gain measurements to infer γ C . The technique described here to measure γ C is independent of gain saturation effects and simplifying assumptions used in the segmented dynode model, both of which can introduce errors when inferring γ C through gain measurements. copyright 1996 American Institute of Physics

Secondary scintillation yield from GEM and THGEM gaseous electron multipliers for direct dark matter search

Science.gov (United States)

Monteiro, C. M. B.; Fernandes, L. M. P.; Veloso, J. F. C. A.; Oliveira, C. A. B.; dos Santos, J. M. F.

2012-07-01

The search for alternatives to PMTs as photosensors in optical TPCs for rare event detection has significantly increased in the last few years. In particular, in view of the next generation large volume detectors, the use of photosensors with lower natural radioactivity, such as large area APDs or GM-APDs, with the additional possibility of sparse surface coverage, triggered the intense study of secondary scintillation production in micropattern electron multipliers, such as GEMs and THGEMs, as alternatives to the commonly used uniform electric field region between two parallel meshes. The much higher scintillation output obtained from the electron avalanches in such microstructures presents an advantage in those situations. The accurate knowledge of the amount of such scintillation is important for correct detector simulation and optimization. It will also serve as a benchmark for software tools developed and/or under development for the calculation of the amount of such scintillation.The secondary scintillation yield, or electroluminescence yield, in the electron avalanches of GEMs and THGEMs operating in gaseous xenon and argon has been determined for different gas pressures. At 1 bar, THGEMs deliver electroluminescence yields that are more than one order of magnitude higher when compared to those achieved in GEMs and two orders of magnitude when compared to those achieved in a uniform field gap. The THGEM electroluminescence yield presents a faster decrease with pressure when comparing to the GEM electroluminescence yield, reaching similar values to what is achieved in GEMs for xenon pressures of 2.5 bar, but still one order of magnitude higher than that produced in a uniform field gap. Another exception is the GEM operating in argon, which presents an electroluminescence yield similar to that produced in a uniform electric field gap, while the THGEM achieves yields that are more than one order of magnitude higher.

Improved Electron Yield and Spin-Polarization from III-V Photocathodes Via Bias Enhanced Carrier Drift

International Nuclear Information System (INIS)

Mulhollan, Gregory A.; Bierman, John; Brachmann, Axel; Clendenin, James E.; Garwin, Edward; Kirby, Robert; Luh, Dah-An

2005-01-01

Spin-polarized electrons are commonly used in high energy physics. Future work will benefit from greater polarization. Polarizations approaching 90% have been achieved at the expense of yield. The primary paths to higher polarization are material design and electron transport. Our work addresses the latter. Photoexcited electrons may be preferentially emitted or suppressed by an electric field applied across the active region. We are tuning this forward bias for maximum polarization and yield, together with other parameters, e.g., doping profile. Preliminary measurements have been carried out on bulk and thin film GaAs. As expected, the yield change far from the bandgap is quite large for bulk material. The bias is applied to the bottom (non-activated) side of the cathode so that the accelerating potential as measured with respect to the ground potential chamber walls is unchanged for different front-to-back cathode bias values. The size of the bias to cause an appreciable effect is rather small reflecting the low drift kinetic energy in the zero bias case

Secondary Electron Yield Measurements and Groove Chambers Tests in the PEP-II Beam Line Straights Sections

International Nuclear Information System (INIS)

Pivi, M

2008-01-01

Beam instability caused by the electron cloud has been observed in positron and proton storage rings and it is expected to be a limiting factor in the performance of the positron Damping Ring (DR) of future Linear Colliders such as ILC and CLIC [1, 2]. In the Positron Low Energy Ring (LER) of the PEP-II accelerator, we have installed vacuum chambers with rectangular grooves in a straight magnetic-free section to test this promising possible electron cloud mitigation technique. We have also installed a special chamber to monitor the secondary electron yield of TiN and TiZrV (NEG) coating, Copper, Stainless Steel and Aluminum under the effect of electron and photon conditioning in situ in the beam line. In this paper, we describe the ongoing R and D effort to mitigate the electron cloud effect for the ILC damping ring, the latest results on in situ secondary electron yield conditioning and recent update on the groove tests in PEP-II

Photo-neutron yields from thin and thick targets irradiated by 2.0 GeV electrons

International Nuclear Information System (INIS)

Hee-Seock, Lee; Syuichi, Ban; Toshiya, Sanami; Kazutoshi, Takahashi; Tatsuhiko, Sato; Kazuo, Shin

2005-01-01

The photo-neutron yields from thin and thick targets irradiated by high energy electrons were studied. The photo-neutron spectra at 90 deg C relative to the incident 2.0 GeV electrons were measured by the pulsed beam time-of-flight technique using the Pilot-U plastic scintillator and the NE213 liquid scintillator with 2 inches in length and 2 inches in diameter. Targets, from low-Z element (carbon) to high-Z element (bismuth) and with thin (0.5 Xo) and thick (10 Xo) thickness, were used in this study. The differential photo-neutron yields between 2 MeV (mainly 8 MeV) and 400 MeV were obtained. The systematics was studied to make empirical yield terms for shielding application. Recently, the study of the angular distributed yields was conducted at two other observing angles, 48 deg C and 140 deg C. The photo-neutron yields between 8 MeV and 250 MeV were obtained for thick targets. The experimental data were compared with results calculated using the EGS4+PICA3 or the MCNPX 2.5d code. (authors)

Electron thermalization distances and free-ion yields in dielectric fluids: Effect of electron scavengers

International Nuclear Information System (INIS)

Gee, N.; Freeman, G.R.

1985-01-01

Free-ion yields were measured in isobutane and in solutions containing sulfur hexafluoride, at densities from the liquid at 295 K to the supercritical fluid. A modified Onsager model was used to estimate the most probable thermalization distances b/sub GP/ (GP denotes a Gaussian power-law distribution). The density-normalized distance b/sub GP/d in isobutane increased from 6.3 x 10 -6 kg/m 2 at 295 K to a maximum of 10.5 x 10 -6 kg/m 2 at 395 K, and then decreased to 5.6 x 10 -6 kg/m 2 at 408 K (T/sub c/). The maximum, which is evidence of conduction-band enhancement of b/sub GP/, was suppressed in solutions containing small amounts of SF 6 . The SF 6 captured the electrons while they were still at epithermal energies, and terminated their flight away from their sibling ions. The values of b/sub GP/ and the free-ion yields were thereby decreased

Total yield and escape depth of electrons from heavy ion solid interactions

International Nuclear Information System (INIS)

Frischkorn, H.J.; Burkhard, M.; Groenveld, K.O.; Hofmann, D.; Koschar, P.; Latz, R.; Schader, J.

1983-01-01

At high projectile energies ( aboutMeV/U) several mechanisms for electron production are discussed as e.g. direct ionization collisions, recoil particle cascades, collective electron emission. Results are presented of total electron yield (#betta#) measurements over a wide projectile energy E /SUB p/ range (40 keV/U< E /SUB p/ /M <12 MeV/U) and a wide projectile Z /SUB p/ range (1<2 /SUB p-/ <92) of both monoionic and molecular projectiles and of different target thicknesses. From the target thickness dependence of #betta# the mean free path lambda of electrons in carbon can be calculated. The data are discussed in the frame of current theories. Significant deviations from calculated values and predicted dependencies are found, in particular for projectile velocities v /SUB p/ close to the Fermi velocity v /SUB F/ of target electrons and for molecular projectile ions

Characteristic and non-characteristic X-ray yields produced from thick Ti element by sub-relativistic electrons

International Nuclear Information System (INIS)

Yadav, Namita; Kumar, Sunil; Bhatt, Pragya; Singh, Raj; Singh, B.K.; Shanker, R.

2012-01-01

Highlights: ► The X-ray spectra of a thick Ti element by 10–25 keV electron impact are obtained. ► Measured Ti K α yields are found to be in good agreement with PWBA theory. ► Doubly differential bremsstrahlung yields agree reasonably with MC simulation. ► Average value of the ratio K α /(K α + K β ) of Ti is found to be 0.881 ± 0.003. -- Abstract: Measurements are performed to study the electron impact energy dependence of doubly differential bremsstrahlung yields (DDBY) and of characteristic Ti K α line yields produced from sub-relativistic electrons (10–25 keV) colliding with a thick Ti (Z = 22) target. The emitted radiation is detected by a Si-PIN photo-diode detector with energy resolution (FWHM) of 180 eV at 5.9 keV. The measured data of DDBY are compared with the results predicted by Monte-Carlo (MC) simulations using the general purpose PENELOPE code. A reasonable agreement is found between experimental and simulation results within the experimental uncertainty of measurements of 12%. Characteristic Ti K α yields are obtained for the considered impact energy range and they are compared with the existing theoretical results. A good agreement is found between the present measurements and the theoretical calculations. Furthermore, data are presented for impact energy dependence of the ratio K α /(K α + K β ) of a thick Ti target under impact of 10–25 keV electrons. The ratio shows a very weak dependence on impact energy in the studied range. The average value of the ratio is found to be 0.881 ± 0.003.

Determination of secondary electron yields from low pressure breakdown

International Nuclear Information System (INIS)

Maric, D; Zivanov, S.; Strinic, A.; Malovic, G.; Djuric, M.; Petrovic, Z. Lj.

2000-01-01

In order to model accurately the secondary yields in gas breakdown and collisional plasmas both the numerous processes discussed in related experiments must be included and also proper determination of γ (E/n) must be provided. In addition to the application of the correct ionization rate it is also essential to include the nonequilibrium region where electrons gain energy and achieve hydrodynamics equilibrium. For lower values of E/n, greater values of γ than those based on the literature data for αn(E/n) have been found, possibly due to existence of the photoelectric effects

Secondary electron yields of carbon-coated and polished stainless steel

International Nuclear Information System (INIS)

Ruzic, D.; Moore, R.; Manos, D.; Cohen, S.

1982-01-01

To increase the power throughput to a plasma of an existing lower hybrid waveguide, secondary electron production on the walls and subsequent electron multiplication must be reduced. Since carbon has a low secondary electron coefficient (delta), measurements were performed for several UHV compatible carbon coatings (Aquadag/sup X/, vacuum pyrolyzed Glyptal/sup X/, and lamp black deposited by electrophoresis) as a function of primary beam voltage (35 eV to 10 keV), surface roughness (60 through 600 grit mechanical polishing and electropolishing), coating thickness, and angle of incidence (theta). Also measured were uncoated stainless steel, Mo, Cu, Ti, TiC, and ATJ graphite. The yields were obtained by varying the sample bias and measuring the collected current while the samples were in the electron beam of a scanning Auger microprobe. This technique allows delta measurements of Auger characterized surfaces with < or =0.3 mm spatial resolution. Results show delta to have a typical energy dependence, with a peak occurring at 200 to 300 eV for normal incidence, and at higher energy for larger theta. In general, delta increases with theta more for smooth surfaces than for rough ones. Ninety percent of the secondary electrons have energies less than 25 eV. Some carbonized coating and surface treatment combinations give delta/sub max/ = 0.88 +- 0.01 for normal electron beam incidence: a reduction of almost 40% compared to untreated stainless steel

Global Annual Final AC Yield Comparison between HCPV and c-Si PV

Directory of Open Access Journals (Sweden)

Juan Pablo Ferrer-Rodríguez

2015-01-01

Full Text Available A worldwide comparison of the annual yield between conventional c-Si photovoltaic (PV technology and high concentrated photovoltaic (HCPV technology is presented. The idea of this paper is to find the most appropriate locations for HCPV systems in terms of the annual energy produced when comparing to fixed tilt PV systems and two-axis oriented PY systems. For estimating the annual energy generation, the method of the Performance Ratio is used. For some locations with high annual direct normal irradiation values, which are distributed around the world, HCPV systems are found to be more advantageous than fixed tilt PV systems. World maps showing this comparison are presented.

Ionization of liquid argon by x-rays: effect of density on electron thermalization and free ion yields

International Nuclear Information System (INIS)

Huang, S.S.-S.; Gee, N.; Freeman, G.R.

1991-01-01

Free ion yields were measured in liquid argon as a function of electric field strength at densities 736-1343 kg/m 3 (temperatures 149-95 K). The field dependence of the yields was parametrized using the extended Onsager and box models. Over the present density range the total ion yield was constant within 1% and was taken as 4.4, the average of earlier values at 87-91 K. The absence of internal vibrational modes in argon makes its electron thermalizing ability smaller than that of methane. The electron thermalization distance b GP in liquid argon is 3-5 times longer than that in liquid methane at a given d/d c (d c = critical fluid density). (author)

Comparison of optical and electron spectra in an infra-red free electron laser

Energy Technology Data Exchange (ETDEWEB)

MacLeod, A.M.; Gillespie, W.A.; Martin, P.F. [Univ. of Abertay, Dundee (United Kingdom)] [and others

1995-12-31

Time-resolved electron and optical spectra recently acquired at the FELIX facility are presented, showing the evolution of the respective macropulses. A comparison is made between the optical power output during the macropulse and the measured power extracted from the electron beam using a simple model of the cavity losses. Data are available for a wide range of operating conditions: the wavelength range is from 9 {mu}m to 28 {mu}m and detuning are between 1/4{lambda} and 2{lambda}. The effect of rapid electron beam energy changes on the optical and electron spectra will also be discussed.

Top layer's thickness dependence on total electron-yield X-ray standing-wave

International Nuclear Information System (INIS)

Ejima, Takeo; Yamazaki, Atsushi; Banse, Takanori; Hatano, Tadashi

2005-01-01

A Mo single-layer film with a stepwise thickness distribution was fabricated on the same Mo/Si reflection multilayer film. Total electron-yield X-ray standing-wave (TEY-XSW) spectra of the aperiodic multilayer were measured with reflection spectra. The peak positions of the standing waves in the TEY-XSW spectra changed as the film thickness of the top Mo-layer increased

The Dose Rate Dependence of the Yield of Trapped Electrons in Crystalline Ice

DEFF Research Database (Denmark)

Nilsson, Johan Daniel Göran; Pagsberg, Palle Bjørn

1980-01-01

in competition with other reactions and we propose a simple model where we assume that the mobile electrons can undergo bimolecular bulk reactions with protons and OH radicals. Rate constants of 3.0 × 1015 M−1 S−1 and 1.4 × 1014 M−1 S−1 for the two reactions were required in the model in order to account......The yield of localized excess electrons in crystalline H2O ice has been studied as a function of the dose rate at various temperatures in the range −10 to −40°C. The G value was found to decrease significantly with increasing dose rate. Thus it appears that the localization of electrons takes place...

Perpendicular electron cyclotron emission from hot electrons in TMX-U

International Nuclear Information System (INIS)

James, R.A.; Ellis, R.F.; Lasnier, C.J.; Casper, T.A.; Celata, C.M.

1984-01-01

Perpendicular electron cyclotron emission (PECE) from the electron cyclotron resonant heating of hot electrons in TMX-U is measured at 30 to 40 and 50 to 75 GHz. This emission is optically thin and is measured at the midplane, f/sub ce/ approx. = 14 GHz, in either end cell. In the west end cell, the emission can be measured at different axial positions thus yielding the temporal history of the hot electron axial profile. These profiles are in excellent agreement with the axial diamagnetic signals. In addition, the PECE signal level correlates well with the diamagnetic signal over a wide range of hot electron densities. Preliminary results from theoretical modeling and comparisons with other diagnostics are also presented

Low Secondary Electron Yield Carbon Coatings for Electron-cloud Mitigation in Modern Particle Accelerators

CERN Document Server

Yin Vallgren, Christina; Calatroni, Sergio; Chiggiato, Paolo; Costa Pinto, Pedro; Marques, Hugo; Neupert, Holger; Taborelli, Mauro; Vollenberg, Wilhelmus; Wevers, Ivo; Yaqub, Kashif

2010-01-01

Electron-cloud is one of the main limitations for particle accelerators with positively charged beams of high intensity and short bunch spacing, as the SPS at CERN. The Secondary Electron Yield (SEY) of the inner surface of the vacuum chamber is the main parameter governing the phenomenon. The effect could be eliminated by coating the vacuum chambers with a material of low SEY, which does not require bake-out and is robust against air exposure. For such a purpose amorphous carbon (a-C) coatings were produced by magnetron sputtering of graphite targets. They exhibit maximum SEY between 0.95 and 1.05 after air transfer to the measuring instrument. After 1 month of air exposure the SEY rises by 10 - 20 % of the initial values. Storage in desiccator or by packaging in Al foil makes this increase negligible. The coatings have a similar X-ray photoelectron spectroscopy (XPS) C1s spectrum for a large set of deposition parameters and exhibit an enlarged linewidth compared to HOPG graphite. The static outgassing witho...

A study of Al/Si interface by photoemission, Auger electron yield and Auger electron spectroscopies

International Nuclear Information System (INIS)

Kobayashi, K.L.I.; Barth, J.; Gerken, F.; Kunz, C.; Deutsches Elektronen-Synchrotron

1980-06-01

Photoemission, Auger electron yield and Auger electron spectra were observed for Al/Si(111) interfaces with various Al coverage prepared by successive deposition using a molecular beam source. The Al 3p derived states are introduced at around the top of the valence band by the Al coverage of less than one monolayer. The Al surface layer behaves as a 'metal' and the Fermi level is stabilized in the Al 3p derived states at about 0.3 eV above the top of the valence band of Si. The Schottky barrier height in this stage is about 0.8 eV and further increase in Al coverage does not change the barrier height. A covalent bonding model of the Al/Si interface based on the experimental results is proposed. The present result favors the on-top geometry of Al atoms on Si(111) surface among the geometries used in the pseudopotential calculation by Zhang and Schlueter. (orig.)

Total yield of channeling radiation from relativistic electrons in thin Si and W crystals

International Nuclear Information System (INIS)

Abdrashitov, S.V.; Bogdanov, O.V.; Dabagov, S.B.; Pivovarov, Yu.L.; Tukhfatullin, T.A.

2013-01-01

Orientation dependences of channeling radiation total yield from relativistic 155–855 MeV electrons at both 〈1 0 0〉 axial and (1 0 0) planar channeling in thin silicon and tungsten crystals are studied by means of computer simulations. The model as well as computer code developed allows getting the quantitative results for orientation dependence of channeling radiation that can be used for crystal alignment in channeling experiments and/or for diagnostics of initial angular divergence of electron beam

Experimental Observations of In-Situ Secondary Electron Yield Reduction in the PEP-II Particle Accelerator Beam Line

International Nuclear Information System (INIS)

Pivi, Mauro

2010-01-01

Beam instability caused by the electron cloud has been observed in positron and proton storage rings and it is expected to be a limiting factor in the performance of the positron Damping Ring (DR) of future Linear Colliders (LC) such as ILC and CLIC. To test a series of promising possible electron cloud mitigation techniques as surface coatings and grooves, in the Positron Low Energy Ring (LER) of the PEP-II accelerator, we have installed several test vacuum chambers including (i) a special chamber to monitor the variation of the secondary electron yield of technical surface materials and coatings under the effect of ion, electron and photon conditioning in situ in the beam line; (ii) chambers with grooves in a straight magnetic-free section; and (iii) coated chambers in a dedicated newly installed 4-magnet chicane to study mitigations in a magnetic field region. In this paper, we describe the ongoing R and D effort to mitigate the electron cloud effect for the LC damping ring, focusing on the first experimental area and on results of the reduction of the secondary electron yield due to in situ conditioning.

Comparison of growth, milk yield and draughtability of Murrah-Philippine crossbred and Philippine native buffaloes

NARCIS (Netherlands)

Salas, R.C.S.; Lende, van der T.; Udo, H.M.J.; Mamuad, F.V.; Garillo, E.P.; Cruz, L.C.

2000-01-01

Data collected between 1981 and 1991 at the Philippine Carabao Center at Central Luzon State University (PCC-CLSU) were used for the comparison of growth, milk yield and draughtability of Murrah-Philippine crossbred and Philippine native buffaloes. Body weights and body measurements were available

Radiolysis of liquid water: an attempt to reconcile Monte-Carlo calculations with new experimental hydrated electron yield data at early times

International Nuclear Information System (INIS)

Muroya, Y.; Meesungnoen, J.; Jay-Gerin, J.-P.; Filali-Mouhim, A.; Goulet, T.; Katsumura, Y.; Mankhetkorn, S.

2002-01-01

A re-examination of our Monte-Carlo modeling of the radiolysis of liquid water by low linear-energy-transfer (LET ∼ 0.3 keV μm -1 ) radiation is undertaken herein in an attempt to reconcile the results of our simulation code with recently revised experimental hydrated electron (e aq - ) yield data at early times. The thermalization distance of subexcitation electrons, the recombination cross section of the electrons with their water parent cations prior to thermalization, and the branching ratios of the different competing mechanisms in the dissociative decay of vibrationally excited states of water molecules were taken as adjustable parameters in our simulations. Using a global-fit procedure, we have been unable to find a set of values for those parameters to simultaneously reproduce (i) the revised e aq - yield of 4.0 ± 0.2 molecules per 100 eV at 'time zero' (that is, a reduction of ∼20% over the hitherto accepted value of 4.8 molecules per 100 eV), (ii) the newly measured e aq - decay kinetic profile from 100 ps to 10 ns, and (iii) the time-dependent yields of the other radiolytic species H . , . OH, H 2 , and H 2 O 2 (up to ∼1 μs). The lowest possible limiting 'time-zero' yield of e aq - that we could in fact obtain, while ensuring an acceptable agreement between all computed and experimental yields, was ∼4.4 to 4.5 molecules per 100 eV. Under these conditions, the mean values of the electron thermalization distance and of the geminate electron-cation recombination probability, averaged over the subexcitation electron 'entry spectrum,' are found to be equal to ∼139 A and ∼18%, respectively. These values are to be compared with those obtained in our previous simulations of liquid water radiolysis, namely ∼88 A and ∼5.5%, respectively. Our average electron thermalization distance is also to be compared with the typical size (∼64-80 A) of the initial hydrated electron distributions estimated in current deterministic models of 'spur' chemistry

Low-energy positron and electron diffraction and positron-stimulated secondary electron emission from Cu(100)

International Nuclear Information System (INIS)

Weiss, A.H.

1983-01-01

The results of two series of experiments are reported. In the first, an electrostatically guided beam of low-energy (40-400 eV) positrons, delta/sub p/ was used to study low-energy positron diffraction (LEPD) from a Cu(100) surface under ultrahigh-vacuum conditions. Low-energy electron diffraction (LEED) data were obtained from the same sample in the same apparatus. Comparison of LEPD and LEED intensity versus energy data with model calculations made using computer programs developed by C.B. Duke and collaborators indicated that: LEPD data is adequately modeled using potentials with no exchange-correlation term. The inelastic mean free path, lambda/sub ee/, is shorter for positrons than for electrons at low (< approx.80 eV). LEED is better than LEPD at making a determination of the first-layer spacing of Cu(100) for the particular data set reported. In the second set of experiments, the same apparatus and sample were used to compare positron- and electron-stimulated secondary-electron emission (PSSEE and ESSEE). The results were found to be consistent with existing models of secondary-electron production for metals. The energy distributions of secondary-electrons had broad low-energy (<10 eV) peaks for both positron and electron stimulation. But the PSEE distribution showed no elastic peak. Measurements of secondary-electron angular distributions, found to be cosine-like in both the PSSEE and ESSEE case, were used to obtain total secondary yield ratios, delta, at four beam energies ranging from 40-400 eV. The secondary yield ratio for primary positrons and the yield for primary electrons, delta/sub e/, were similar at these energies. For 400-eV primary particles the secondary yields were found to be delta/sub p/ = 0.94 +/- 0.12 and delta/sub e/ = 0.94 +/- 0./12, giving a ratio of unity for positron-stimulated secondary yield to electron-stimulated secondary yield

Electron states in semiconductor quantum dots

International Nuclear Information System (INIS)

Dhayal, Suman S.; Ramaniah, Lavanya M.; Ruda, Harry E.; Nair, Selvakumar V.

2014-01-01

In this work, the electronic structures of quantum dots (QDs) of nine direct band gap semiconductor materials belonging to the group II-VI and III-V families are investigated, within the empirical tight-binding framework, in the effective bond orbital model. This methodology is shown to accurately describe these systems, yielding, at the same time, qualitative insights into their electronic properties. Various features of the bulk band structure such as band-gaps, band curvature, and band widths around symmetry points affect the quantum confinement of electrons and holes. These effects are identified and quantified. A comparison with experimental data yields good agreement with the calculations. These theoretical results would help quantify the optical response of QDs of these materials and provide useful input for applications

Comparison of Grain Yield and Some Characteristics of Hulled, Durum and Bread Wheat Genotypes Varieties

Directory of Open Access Journals (Sweden)

Bekir Atar

2017-02-01

Full Text Available In spite of the low grain yield they produce, the hulled wheat have become even more important in recent years because of their resistance to negative environmental conditions and healthy nutritional content. The research was carry out in order to comparison the yield and yield characteristics of durum (Kiziltan-91 and C-1252, hulled (Einkorn and Emmer and bread wheat (Tir varieties in Isparta ecological conditions in 2013-14 and 2014-15 vegetation periods. In both years, the highest grain yield was obtained in Kiziltan-91 variety (3992 and 3758 kg ha-1 respectively. The grain yield of hulled wheats in the first year (Einkorn 1269 kg ha-1, Emmer 2125 kg ha-1 was around Turkey averages. However, grain yield decreased of commercial wheat varieties due to the negative effect of high amount of rainfall in June in the second year, but considerably increased in (Einkorn 2150 kg ha-1, Emmer 2533 kg ha-1. N uptake was found to be lower in the than durum wheats. In terms of grain protein content, the highest values were obtained in Emmer variety (16.4%-15.3%.

Model Comparison for Electron Thermal Transport

Science.gov (United States)

Moses, Gregory; Chenhall, Jeffrey; Cao, Duc; Delettrez, Jacques

2015-11-01

Four electron thermal transport models are compared for their ability to accurately and efficiently model non-local behavior in ICF simulations. Goncharov's transport model has accurately predicted shock timing in implosion simulations but is computationally slow and limited to 1D. The iSNB (implicit Schurtz Nicolai Busquet electron thermal transport method of Cao et al. uses multigroup diffusion to speed up the calculation. Chenhall has expanded upon the iSNB diffusion model to a higher order simplified P3 approximation and a Monte Carlo transport model, to bridge the gap between the iSNB and Goncharov models while maintaining computational efficiency. Comparisons of the above models for several test problems will be presented. This work was supported by Sandia National Laboratory - Albuquerque and the University of Rochester Laboratory for Laser Energetics.

Signal yields of keV electronic recoils and their discrimination from nuclear recoils in liquid xenon

Science.gov (United States)

Aprile, E.; Aalbers, J.; Agostini, F.; Alfonsi, M.; Amaro, F. D.; Anthony, M.; Arneodo, F.; Barrow, P.; Baudis, L.; Bauermeister, B.; Benabderrahmane, M. L.; Berger, T.; Breur, P. A.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Bütikofer, L.; Calvén, J.; Cardoso, J. M. R.; Cervantes, M.; Cichon, D.; Coderre, D.; Colijn, A. P.; Conrad, J.; Cussonneau, J. P.; Decowski, M. P.; de Perio, P.; di Gangi, P.; di Giovanni, A.; Diglio, S.; Eurin, G.; Fei, J.; Ferella, A. D.; Fieguth, A.; Fulgione, W.; Gallo Rosso, A.; Galloway, M.; Gao, F.; Garbini, M.; Geis, C.; Goetzke, L. W.; Grandi, L.; Greene, Z.; Grignon, C.; Hasterok, C.; Hogenbirk, E.; Howlett, J.; Itay, R.; Kaminsky, B.; Kazama, S.; Kessler, G.; Kish, A.; Landsman, H.; Lang, R. F.; Lellouch, D.; Levinson, L.; Lin, Q.; Lindemann, S.; Lindner, M.; Lombardi, F.; Lopes, J. A. M.; Mahlstedt, J.; Manfredini, A.; Maris, I.; Marrodán Undagoitia, T.; Masbou, J.; Massoli, F. V.; Masson, D.; Mayani, D.; Messina, M.; Micheneau, K.; Molinario, A.; Morâ, K.; Murra, M.; Naganoma, J.; Ni, K.; Oberlack, U.; Pakarha, P.; Pelssers, B.; Persiani, R.; Piastra, F.; Pienaar, J.; Pizzella, V.; Piro, M.-C.; Plante, G.; Priel, N.; Ramírez García, D.; Rauch, L.; Reichard, S.; Reuter, C.; Rizzo, A.; Rupp, N.; Saldanha, R.; Dos Santos, J. M. F.; Sartorelli, G.; Scheibelhut, M.; Schindler, S.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Shagin, P.; Shockley, E.; Silva, M.; Simgen, H.; Sivers, M. V.; Stein, A.; Thers, D.; Tiseni, A.; Trinchero, G.; Tunnell, C.; Vargas, M.; Wang, H.; Wang, Z.; Wei, Y.; Weinheimer, C.; Wittweg, C.; Wulf, J.; Ye, J.; Zhang, Y.; Zhu, T.; Xenon Collaboration

2018-05-01

We report on the response of liquid xenon to low energy electronic recoils below 15 keV from beta decays of tritium at drift fields of 92 V /cm , 154 V /cm and 366 V /cm using the XENON100 detector. A data-to-simulation fitting method based on Markov Chain Monte Carlo is used to extract the photon yields and recombination fluctuations from the experimental data. The photon yields measured at the two lower fields are in agreement with those from literature; additional measurements at a higher field of 366 V /cm are presented. The electronic and nuclear recoil discrimination as well as its dependence on the drift field and photon detection efficiency are investigated at these low energies. The results provide new measurements in the energy region of interest for dark matter searches using liquid xenon.

Detailed characterization of electron sources yielding first demonstration of European X-ray Free-Electron Laser beam quality

Directory of Open Access Journals (Sweden)

F. Stephan

2010-02-01

Full Text Available The photoinjector test facility at DESY, Zeuthen site (PITZ, was built to develop and optimize photoelectron sources for superconducting linacs for high-brilliance, short-wavelength free-electron laser (FEL applications like the free-electron laser in Hamburg (FLASH and the European x-ray free-electron laser (XFEL. In this paper, the detailed characterization of two laser-driven rf guns with different operating conditions is described. One experimental optimization of the beam parameters was performed at an accelerating gradient of about 43  MV/m at the photocathode and the other at about 60  MV/m. In both cases, electron beams with very high phase-space density have been demonstrated at a bunch charge of 1 nC and are compared with corresponding simulations. The rf gun optimized for the lower gradient has surpassed all the FLASH requirements on beam quality and rf parameters (gradient, rf pulse length, repetition rate and serves as a spare gun for this facility. The rf gun studied with increased accelerating gradient at the cathode produced beams with even higher brightness, yielding the first demonstration of the beam quality required for driving the European XFEL: The geometric mean of the normalized projected rms emittance in the two transverse directions was measured to be 1.26±0.13  mm mrad for a 1-nC electron bunch. When a 10% charge cut is applied excluding electrons from those phase-space regions where the measured phase-space density is below a certain level and which are not expected to contribute to the lasing process, the normalized projected rms emittance is about 0.9 mm mrad.

Ion induced electron emission statistics under Agm- cluster bombardment of Ag

Science.gov (United States)

Breuers, A.; Penning, R.; Wucher, A.

2018-05-01

The electron emission from a polycrystalline silver surface under bombardment with Agm- cluster ions (m = 1, 2, 3) is investigated in terms of ion induced kinetic excitation. The electron yield γ is determined directly by a current measurement method on the one hand and implicitly by the analysis of the electron emission statistics on the other hand. Successful measurements of the electron emission spectra ensure a deeper understanding of the ion induced kinetic electron emission process, with particular emphasis on the effect of the projectile cluster size to the yield as well as to emission statistics. The results allow a quantitative comparison to computer simulations performed for silver atoms and clusters impinging onto a silver surface.

In-situ measurements of the secondary electron yield in an accelerator environment: Instrumentation and methods

International Nuclear Information System (INIS)

Hartung, W.H.; Asner, D.M.; Conway, J.V.; Dennett, C.A.; Greenwald, S.; Kim, J.-S.; Li, Y.; Moore, T.P.; Omanovic, V.; Palmer, M.A.; Strohman, C.R.

2015-01-01

The performance of a particle accelerator can be limited by the build-up of an electron cloud (EC) in the vacuum chamber. Secondary electron emission from the chamber walls can contribute to EC growth. An apparatus for in-situ measurements of the secondary electron yield (SEY) in the Cornell Electron Storage Ring (CESR) was developed in connection with EC studies for the CESR Test Accelerator program. The CESR in-situ system, in operation since 2010, allows for SEY measurements as a function of incident electron energy and angle on samples that are exposed to the accelerator environment, typically 5.3 GeV counter-rotating beams of electrons and positrons. The system was designed for periodic measurements to observe beam conditioning of the SEY with discrimination between exposure to direct photons from synchrotron radiation versus scattered photons and cloud electrons. The samples can be exchanged without venting the CESR vacuum chamber. Measurements have been done on metal surfaces and EC-mitigation coatings. The in-situ SEY apparatus and improvements to the measurement tools and techniques are described

In-situ measurements of the secondary electron yield in an accelerator environment: Instrumentation and methods

Energy Technology Data Exchange (ETDEWEB)

Hartung, W.H., E-mail: wh29@cornell.edu; Asner, D.M.; Conway, J.V.; Dennett, C.A.; Greenwald, S.; Kim, J.-S.; Li, Y.; Moore, T.P.; Omanovic, V.; Palmer, M.A.; Strohman, C.R.

2015-05-21

The performance of a particle accelerator can be limited by the build-up of an electron cloud (EC) in the vacuum chamber. Secondary electron emission from the chamber walls can contribute to EC growth. An apparatus for in-situ measurements of the secondary electron yield (SEY) in the Cornell Electron Storage Ring (CESR) was developed in connection with EC studies for the CESR Test Accelerator program. The CESR in-situ system, in operation since 2010, allows for SEY measurements as a function of incident electron energy and angle on samples that are exposed to the accelerator environment, typically 5.3 GeV counter-rotating beams of electrons and positrons. The system was designed for periodic measurements to observe beam conditioning of the SEY with discrimination between exposure to direct photons from synchrotron radiation versus scattered photons and cloud electrons. The samples can be exchanged without venting the CESR vacuum chamber. Measurements have been done on metal surfaces and EC-mitigation coatings. The in-situ SEY apparatus and improvements to the measurement tools and techniques are described.

Fission product yields

International Nuclear Information System (INIS)

Valenta, V.; Hep, J.

1978-01-01

Data are summed up necessary for determining the yields of individual fission products from different fissionable nuclides. Fractional independent yields, cumulative and isobaric yields are presented here for the thermal fission of 235 U, 239 Pu, 241 Pu and for fast fission (approximately 1 MeV) of 235 U, 238 U, 239 Pu, 241 Pu; these values are included into the 5th version of the YIELDS library, supplementing the BIBFP library. A comparison is made of experimental data and possible improvements of calculational methods are suggested. (author)

Molecular dynamics simulations with electronic stopping can reproduce experimental sputtering yields of metals impacted by large cluster ions

Science.gov (United States)

Tian, Jiting; Zhou, Wei; Feng, Qijie; Zheng, Jian

2018-03-01

An unsolved problem in research of sputtering from metals induced by energetic large cluster ions is that molecular dynamics (MD) simulations often produce sputtering yields much higher than experimental results. Different from the previous simulations considering only elastic atomic interactions (nuclear stopping), here we incorporate inelastic electrons-atoms interactions (electronic stopping, ES) into MD simulations using a friction model. In this way we have simulated continuous 45° impacts of 10-20 keV C60 on a Ag(111) surface, and found that the calculated sputtering yields can be very close to the experimental results when the model parameter is appropriately assigned. Conversely, when we ignore the effect of ES, the yields are much higher, just like the previous studies. We further expand our research to the sputtering of Au induced by continuous keV C60 or Ar100 bombardments, and obtain quite similar results. Our study indicates that the gap between the experimental and the simulated sputtering yields is probably induced by the ignorance of ES in the simulations, and that a careful treatment of this issue is important for simulations of cluster-ion-induced sputtering, especially for those aiming to compare with experiments.

Calculated /alpha/-induced thick target neutron yields and spectra, with comparison to measured data

International Nuclear Information System (INIS)

Wilson, W.B.; Bozoian, M.; Perry, R.T.

1988-01-01

One component of the neutron source associated with the decay of actinide nuclides in many environments is due to the interaction of decay /alpha/ particles in (/alpha/,n) reactions on low Z nuclides. Measurements of (/alpha/,n) thick target neutron yields and associated neutron spectra have been made for only a few combinations of /alpha/ energy and target nuclide or mixtures of actinide and target nuclides. Calculations of thick target neutron yields and spectra with the SOURCES code require /alpha/-energy-dependent cross sections for (/alpha/,n) reactions, as well as branching fractions leading to the energetically possible levels of the product nuclides. A library of these data has been accumulated for target nuclides of Z /le/ 15 using that available from measurements and from recent GNASH code calculations. SOURCES, assuming neutrons to be emitted isotopically in the center-of-mass system, uses libraries of /alpha/ stopping cross sections, (/alpha/,n) reaction cross reactions, product nuclide level branching fractions, and actinide decay /alpha/ spectra to calculate thick target (/alpha/,n) yields and neutron spectra for homogeneous combinations of nuclides. The code also calculates the thick target yield and angle intergrated neutron spectrum produced by /alpha/-particle beams on targets of homogeneous mixtures of nuclides. Illustrative calculated results are given and comparisons are made with measured thick target yields and spectra. 50 refs., 1 fig., 2 tabs

Comparison ofYield of TwelveBasilCultivarsinTwo Provinces:Isfahan and Mazandaran

Directory of Open Access Journals (Sweden)

Nahid Amoli

2017-12-01

Full Text Available Introduction: Basil(Ocimumbasilicum L.is a diploid plant with48chromosomes. Basil isthe aromatic annual herbofthe Lamiaceae familyofleafy vegetablesandhas mentionedand originated inIndiaandIran. Basilhasiron, calcium, magnesium, potassiumandvitamins Aand B. More than 60 varietiesof basilhave been identifiedthathavegreenleavesandredto purple.The performance of15varietiesof basilin Mazandaran province were studied, genotypescollected fromSari(darkgreen withthe23.63 tha-1(fresh weight had thehighestyield. In comparison, 38the massbasil, withtwocultivars(Opal andKashkanyLulu, localpopulationsofmanyof the traits(e.g.,length and width ofleavesandfresh and dry weight showed superiority than cultivars. Incomparing the performance of38varietiesof basilinItaly, drymatter yieldper hectarerangedfrom1812 to6165kg ha-1thatthis wasmore attributestobegenetic aspects. Landraces ofbasilhavevaluabletraitssuch asdrought resistance, saltresistance, resistancetodisease, resistancetocoldandheat. In order to achieveoptimalpopulationpurple basil with high-performance inIsfahan andMazandaran, the present studywas conducted usingsomeof the populationinthese two provinces. Materials and Methods: The number of populations of purple basil wasstudied toselect superior genotypes according to the yield and adaptation to climatic conditions in two provinces at Agricultural Research Station Gharahil of Mazandaran and Kabootarabad of Isfahan. The experiment was conducted as a randomized complete block design with three replications with seeds collected from two areas of the province (a total of 12 varieties of basil during one year. Land preparationwas consisted ofplowanddiscperpendicular to each other(for crushinghunk and thenlevelingandplotsofland. Inprovinces, nitrogen, phosphorusandpotassiumfertilizerwas used based on soiltest.In this experiment,harvest time was4st. for every two region. Duringthe growing seasonweed controlwascarried outmechanically. Result and Discussions: In

Comparison of heavy metal loads in stormwater runoff from major and minor urban roads using pollutant yield rating curves

International Nuclear Information System (INIS)

Davis, Brett; Birch, Gavin

2010-01-01

Trace metal export by stormwater runoff from a major road and local street in urban Sydney, Australia, is compared using pollutant yield rating curves derived from intensive sampling data. The event loads of copper, lead and zinc are well approximated by logarithmic relationships with respect to total event discharge owing to the reliable appearance of a first flush in pollutant mass loading from urban roads. Comparisons of the yield rating curves for these three metals show that copper and zinc export rates from the local street are comparable with that of the major road, while lead export from the local street is much higher, despite a 45-fold difference in traffic volume. The yield rating curve approach allows problematic environmental data to be presented in a simple yet meaningful manner with less information loss. - A simple method for representing data onroad runoff pollution allows comparisons among dissimilar sites and could form the basis for a pollution database.

Electron transport phosphorylation in rumen butyrivibrios: unprecedented ATP yield for glucose fermentation to butyrate

Directory of Open Access Journals (Sweden)

Timothy eHackmann

2015-06-01

Full Text Available From a genomic analysis of rumen butyrivibrios (Butyrivibrio and Pseudobutyrivibrio spp., we have re-evaluated the contribution of electron transport phosphorylation to ATP formation in this group. This group is unique in that most (76% genomes were predicted to possess genes for both Ech and Rnf transmembrane ion pumps. These pumps act in concert with the NifJ and Bcd-Etf to form a electrochemical potential (ΔμH+ and ΔμNa+, which drives ATP synthesis by electron transport phosphorylation. Of the 62 total butyrivibrio genomes currently available from the Hungate 1000 project, all 62 were predicted to possess NifJ, which reduces oxidized ferredoxin (Fdox during pyruvate conversion to acetyl-CoA. All 62 possessed all subunits of Bcd-Etf, which reduces Fdox and oxidizes reduced NAD (NADred during crotonyl-CoA reduction. Additionally, 61 genomes possessed all subunits of the Rnf, which generates ΔμH+ or ΔμNa+ from oxidation of reduced Fd and reduction of oxidized NAD (NADox. Further, 47 genomes possessed all 6 subunits of the Ech, which generates ΔμH+ from oxidation of reduced Fd (Fdred. For glucose fermentation to butyrate and H2, the electrochemical potential established should drive synthesis of ~1.5 ATP by the F0F1-ATP synthase (possessed by all 62 genomes. The total yield is ~4.5 ATP/glucose after accounting for 3 ATP formed by classic substrate-level phosphorylation, and it is one the highest yields for any glucose fermentation. The yield was the same when unsaturated fatty acid bonds, not H+, served as the electron acceptor (as during biohydrogenation. Possession of both Ech and Rnf had been previously documented in only a few sulfate-reducers, was rare in other rumen prokaryotic genomes in our analysis, and may confer an energetic advantage to rumen butyrivibrios. This unique energy conservation system might enhance the butyrivibrios’ ability to overcome growth inhibition by unsaturated fatty acids, as postulated herein.

Characterization of Carbon Coatings with Low Secondary Electron Yield

CERN Document Server

Yin Vallgren, C; Costa Pinto, P; Kuzucan, A; Neupert, H; Taborelli, M

2011-01-01

Amorphous carbon (a-C) coatings can reliably be produced with a maximum secondary electron yield (SEY) close to 1 at room temperature. Measurements at low temperature (LHe) are in progress. Analysis by X-ray Photoemission Spectroscopy (XPS) shows a correlation between the lineshape of C1s spectrum in XPS and the maximum SEY of the investigated samples. The initial level of oxygen on the surface of the various samples does not seem to be related to the initial maximum SEY value. However, the increase of the SEY with air exposure time on each individual sample is related to the amount of oxygen containing adsorbates. Storage in different environments has been investigated (static vacuum, aluminium foil, dry nitrogen and desiccators), and shows significant differences in the “aging” behaviour. Aging is very moderate when storing samples wrapped in aluminium foil in air. Samples which have undergone aging due to inappropriate storage can be recovered nearly to the initial value of their SEY by surface treatme...

Signal yields, energy resolution, and recombination fluctuations in liquid xenon

Science.gov (United States)

Akerib, D. S.; Alsum, S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Biesiadzinski, T. P.; Boulton, E. M.; Bramante, R.; Brás, P.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Chiller, A. A.; Chiller, C.; Currie, A.; Cutter, J. E.; Davison, T. J. R.; Dobi, A.; Dobson, J. E. Y.; Druszkiewicz, E.; Edwards, B. N.; Faham, C. H.; Fiorucci, S.; Gaitskell, R. J.; Gehman, V. M.; Ghag, C.; Gibson, K. R.; Gilchriese, M. G. D.; Hall, C. R.; Hanhardt, M.; Haselschwardt, S. J.; Hertel, S. A.; Hogan, D. P.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Ihm, M.; Jacobsen, R. G.; Ji, W.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Knoche, R.; Larsen, N. A.; Lee, C.; Lenardo, B. G.; Lesko, K. T.; Lindote, A.; Lopes, M. I.; Manalaysay, A.; Mannino, R. L.; Marzioni, M. F.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morad, J. A.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; O'Sullivan, K.; Oliver-Mallory, K. C.; Palladino, K. J.; Pease, E. K.; Phelps, P.; Reichhart, L.; Rhyne, C.; Shaw, S.; Shutt, T. A.; Silva, C.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Stephenson, S.; Sumner, T. J.; Szydagis, M.; Taylor, D. J.; Taylor, W. C.; Tennyson, B. P.; Terman, P. A.; Tiedt, D. R.; To, W. H.; Tripathi, M.; Tvrznikova, L.; Uvarov, S.; Verbus, J. R.; Webb, R. C.; White, J. T.; Whitis, T. J.; Witherell, M. S.; Wolfs, F. L. H.; Xu, J.; Yazdani, K.; Young, S. K.; Zhang, C.; LUX Collaboration

2017-01-01

This work presents an analysis of monoenergetic electronic recoil peaks in the dark-matter-search and calibration data from the first underground science run of the Large Underground Xenon (LUX) detector. Liquid xenon charge and light yields for electronic recoil energies between 5.2 and 661.7 keV are measured, as well as the energy resolution for the LUX detector at those same energies. Additionally, there is an interpretation of existing measurements and descriptions of electron-ion recombination fluctuations in liquid xenon as limiting cases of a more general liquid xenon recombination fluctuation model. Measurements of the standard deviation of these fluctuations at monoenergetic electronic recoil peaks exhibit a linear dependence on the number of ions for energy deposits up to 661.7 keV, consistent with previous LUX measurements between 2 and 16 keV with 3H. We highlight similarities in liquid xenon recombination for electronic and nuclear recoils with a comparison of recombination fluctuations measured with low-energy calibration data.

Boosting biomethane yield and production rate with graphene: The potential of direct interspecies electron transfer in anaerobic digestion.

Science.gov (United States)

Lin, Richen; Cheng, Jun; Zhang, Jiabei; Zhou, Junhu; Cen, Kefa; Murphy, Jerry D

2017-09-01

Interspecies electron transfer between bacteria and archaea plays a vital role in enhancing energy efficiency of anaerobic digestion (AD). Conductive carbon materials (i.e. graphene nanomaterial and activated charcoal) were assessed to enhance AD of ethanol (a key intermediate product after acidogenesis of algae). The addition of graphene (1.0g/L) resulted in the highest biomethane yield (695.0±9.1mL/g) and production rate (95.7±7.6mL/g/d), corresponding to an enhancement of 25.0% in biomethane yield and 19.5% in production rate. The ethanol degradation constant was accordingly improved by 29.1% in the presence of graphene. Microbial analyses revealed that electrogenic bacteria of Geobacter and Pseudomonas along with archaea Methanobacterium and Methanospirillum might participate in direct interspecies electron transfer (DIET). Theoretical calculations provided evidence that graphene-based DIET can sustained a much higher electron transfer flux than conventional hydrogen transfer. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nature of the concentration thresholds of europium atom yield from the oxidized tungsten surface under electron stimulated desorption

CERN Document Server

Davydov, S Y

2002-01-01

The nature of the electron-stimulated desorption (ESD) of the europium atoms by the E sub e irradiating electrons energies, equal to 50 and 80 eV, as well as peculiarities of the Eu atoms yield dependence on their concentration on the oxidized tungsten surface are discussed. It is shown, that the ESD originates by the electron transition from the interval 5p- or 5s shell of the tungsten surface atom onto the oxygen external unfilled 2p-level

Studying sulfur functional groups in Norway spruce year rings using S L-edge total electron yield spectroscopy

International Nuclear Information System (INIS)

Struis, Rudolf P.W.J.; Ludwig, Christian; Barrelet, Timothee; Kraehenbuehl, Urs; Rennenberg, Heinz

2008-01-01

Profiles of the major sulfur functional groups in mature Norway spruce wood tissue have been established for the first time. The big challenge was the development of a method suitable for sulfur speciation in samples with very low sulfur content (< 100 ppm). This became possible by synchrotron X-ray absorption spectroscopy at the sulfur L-edge in total electron yield (TEY) detection mode with thin gold-coated wood slices. Functional groups were identified using sulfur compound spectra as fingerprints. Latewood of single year rings revealed metabolic plausible sulfur forms, particularly inorganic sulfide, organic disulfide, methylthiol, and highly oxidized sulfur. Form-specific profiles with Norway spruces from three different Swiss forest sites revealed high, but hitherto little-noticed, sulfur intensities attributable to natural heartwood formation and a common, but physiologically unexpected maximum around year ring 1986 with trees from the industrialized Swiss Plateau. It is hypothesized whether it may have resulted from the huge reduction in sulfur emissions after 1980 due to Swiss policy. Comparison with total S content profiles from optical emission spectroscopy underlined the more accurate and temporally better resolved TEY data with single wood year rings and it opened novel insights into the wood cell chemistry

Core-excitation processes of O(1s) in CO, CO{sub 2} and OCS molecules by electron impact

Energy Technology Data Exchange (ETDEWEB)

Arretche, F; Mazon, K T; Falck, A S; Marin, A; Oliveira, H L; Pessoa, O A; Travessini, D; Michelin, S E; Fujimoto, M M; Lee, M T [Departamento de Fisica, UFSC, 88040-900 Florianopolis, SC (Brazil) and Departamento de Fisica, UFPR, 81531-990 Curitiba, PR (Brazil) and Departamento de Quimica, UFSCar, 13565-905, Sao Carlos, SP (Brazil)], E-mail: farretche@hotmail.com

2008-05-15

Distorted-wave approximation is applied to study electron-impact excitation of core electrons in CO{sub 2}, CO and OCS. Differential and integral cross sections for the transitions: X{sup 1}{sigma}{sup +}{sub g} {yields} {sup 1,3} {pi}{sub u}(1{sigma}{sub g} {yields} 2{pi}{sub u}) in CO{sub 2}, X{sup 1}{sigma}{sup +} {yields} {sup 1,3} {pi} (2{sigma} {yields} 4{pi}) in OCS, and X{sup 1}{sigma}{sup +} {yields} {sup 1,3} {pi} (1{sigma} {yields} 2{pi}) in CO are calculated and reported in the (550-1000)-eV incident energy range. Comparison is made among the calculated data for the three targets. The physical origins of the similarity and difference of these data are also discussed. In addition, the generalized oscillator strengths for singlet 1{sigma}{sub g} {yields} 2{pi}{sub u} and 1{sigma}{sub u} {yields} 2{pi}{sub u} transitions for CO{sub 2} are calculated at 1300 eV. The comparison of these results with the available data in the literature is encouraging.{sup 1}.

Note: Theoretical study on the gas pressure dependence of x-ray yield in TE111 cavity based electron cyclotron resonance x-ray source

International Nuclear Information System (INIS)

Selvakumaran, T. S.; Sen, Soubhadra; Baskaran, R.

2014-01-01

Adopting Langevin methodology, a pressure dependent frictional force term which represents the collisional effect is added to the Lorentz equation. The electrons are assumed to be starting from the uniformly distributed co-ordinates on the central plane. The trajectory of each electron is numerically simulated by solving the modified Lorentz equation for a given pressure. The Bremsstrahlung x-ray energy spectrum for each electron crossing the cavity wall boundary is obtained using the Duane-Hunt law. The total x-ray yield is estimated by adding the spectral contribution of each electron. The calculated yields are compared with the experimental results and a good agreement is found

Independent Yields of Kr Isotopes at Photofission of $^{232}$Th and $^{238}$U

CERN Document Server

Gangrsky, Yu P; Zemlyanoi, S G; Maslova, N Yu; Myshinskii, G V; Norov, K S; Penionzhkevich, Yu E; Selesh, O

2002-01-01

The yields of the primary fission fragments - Kr isotopes - at the photofission of ^{232}Th and ^{238}U were measured. The experiments were performed at the microtron of FLNR, JINR, with the energy of the accelerated electrons 25 MeV. The methodic of fission fragments transportation by the gas flow through the capillary and condensation of the inert gases in the cryostat at the liquid nitrogen temperature was used. The fission fragments of other elements were stopped by the filter on the entrance of the capillary. The identification of the Kr isotopes was performed using the gamma-spectra of their daughter products. The mass distribution of the Kr isotopes independent yields was obtained and the comparison with yields at the prompt and thermal neutron fission was discussed.

Comparison of secondary ion emission yields for poly-tyrosine between cluster and heavy ion impacts

International Nuclear Information System (INIS)

Hirata, K.; Saitoh, Y.; Chiba, A.; Yamada, K.; Takahashi, Y.; Narumi, K.

2010-01-01

Emission yields of secondary ions necessary for the identification of poly-tyrosine were compared for incident ion impacts of energetic cluster ions (0.8 MeV C 8 + , 2.4 MeV C 8 + , and 4.0 MeV C 8 + ) and swift heavy monoatomic molybdenum ions (4.0 MeV Mo + and 14 MeV Mo 4+ ) with similar mass to that of the cluster by time-of-flight secondary ion mass analysis combined with secondary ion electric current measurements. The comparison revealed that (1) secondary ion emission yields per C 8 + impact increase with increasing incident energy within the energy range examined, (2) the 4.0 MeV C 8 + impact provides higher emission yields than the impact of the monoatomic Mo ion with the same incident energy (4.0 MeV Mo + ), and (3) the 2.4 MeV C 8 + impact exhibits comparable emission yields to that for the Mo ion impact with higher incident energy (14 MeV Mo 4+ ). Energetic cluster ion impacts effectively produce the characteristic secondary ions for poly-tyrosine, which is advantageous for highly sensitive amino acid detection in proteins using time-of-flight secondary ion mass analysis.

Convenient determination of luminescence quantum yield using a combined electronic absorption and emission spectrometer

Energy Technology Data Exchange (ETDEWEB)

Prakash, John; Mishra, Ashok Kumar [Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India)

2016-01-15

It is possible to measure luminescence quantum yield in a facile way, by designing an optical spectrometer capable of obtaining electronic absorption as well as luminescence spectra, with a setup that uses the same light source and detector for both the spectral measurements. Employment of a single light source and single detector enables use of the same correction factor profile for spectral corrections. A suitable instrumental scaling factor is used for adjusting spectral losses.

Projectile- and charge-state-dependent electron yields from ion penetration of solids as a probe of preequilibrium stopping power

DEFF Research Database (Denmark)

Rothard, H.; Schou, Jørgen; Groeneveld, K.-O.

1992-01-01

Kinetic electron-emission yields gamma from swift ion penetration of solids are proportional to the (electronic) stopping power gamma approximately Beta-S*, if the preequilibrium evolution of the charge and excitation states of the positively charged ions is taken into account. We show...... by investigating the "transport factor" beta, the energy spectrum of directly ejected recoil electrons and the evolution of ionic charge state inside solids. Estimates of the energy-loss fraction leading to electron emission and the effective charges of the ions near the surface allow a quantitative description...

Chlorella vulgaris vs cyanobacterial biomasses: Comparison in terms of biomass productivity and biogas yield

International Nuclear Information System (INIS)

Mendez, Lara; Mahdy, Ahmed; Ballesteros, Mercedes; González-Fernández, Cristina

2015-01-01

Highlights: • Cyanobacteria and C. vulgaris were compared in terms of growth and methane production. • Biomasses were subjected to anaerobic digestion without applying any disruption method. • Cyanobacteria showed an increased methane yield in comparison with C. vulgaris. - Abstract: The aim of the present study was to compare cyanobacteria strains (Aphanizomenon ovalisporum, Anabaena planctonica, Borzia trilocularis and Synechocystis sp.) and microalgae (Chlorella vulgaris) in terms of growth rate, biochemical profile and methane production. Cyanobacteria growth rate ranged 0.5–0.6 day −1 for A. planctonica, A. ovalisporum and Synecochystis sp. and 0.4 day −1 for B. tricularis. Opposite, C. vulgaris maximum growth rate was double (1.2 day −1 ) than that of cyanobacteria. Regarding the methane yield, microalgae C. vulgaris averaged 120 mL CH 4 g COD in −1 due to the presence of a strong cell wall. On the other hand, anaerobic digestion of cyanobacteria supported higher methane yields. B. trilocularis and A. planctonica presented 1.42-fold higher methane yield than microalgae while this value was raised to approximately 1.85-fold for A. ovalisporum and Synechochystis sp. In the biogas production context, this study showed that the low growth rates of cyanobacteria can be overcome by their increased anaerobic digestibility when compared to their microalgae counterpartners, such is the case of C. vulgaris

Time-dependent radiolytic yields at room temperature and temperature-dependent absorption spectra of the solvated electrons in polyols

International Nuclear Information System (INIS)

Lin Mingzhang; Mostafavi, M.; Lampre, I.; Muroya, Y.; Katsumura, Y.

2007-01-01

The molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900, 970, and 1000 mol -1 ·m 2 for 1,2-ethanediol (12ED), 1,2-propanediol (12PD), and 1,3-propanediol (13PD), respectively. These values are two-third or three-fourth of the value usually reported in the published report. Picosecond pulse radiolysis studies have aided in depicting the radiolytic yield of the solvated electron in these solvents as a function of time from picosecond to microsecond. The radiolytic yield in these viscous solvents is found to be strongly different from that of the water solution. The temperature dependent absorption spectra of the solvated electron in 12ED, 12PD, and 13PD have been also investigated. In all the three solvents, the optical spectra shift to the red with increasing temperature. While the shape of the spectra does not change in 13PD, a widening on the blue side of the absorption band is observed in 12ED and 12PD at elevated temperatures. (authors)

Secondary electron emission yield in the limit of low electron energy

CERN Document Server

Andronov, A.N.; Kaganovich, I.D.; Startsev, E.A.; Raitses, Y.; Demidov, V.I.

2013-04-22

Secondary electron emission (SEE) from solids plays an important role in many areas of science and technology.1 In recent years, there has been renewed interest in the experimental and theoretical studies of SEE. A recent study proposed that the reflectivity of very low energy electrons from solid surface approaches unity in the limit of zero electron energy2,3,4, If this was indeed the case, this effect would have profound implications on the formation of electron clouds in particle accelerators,2-4 plasma measurements with electrostatic Langmuir probes, and operation of Hall plasma thrusters for spacecraft propulsion5,6. It appears that, the proposed high electron reflectivity at low electron energies contradicts to numerous previous experimental studies of the secondary electron emission7. The goal of this note is to discuss possible causes of these contradictions.

Unique electron polarimeter analyzing power comparison and precision spin-based energy measurement

International Nuclear Information System (INIS)

Joseph Grames; Charles Sinclair; Joseph Mitchell; Eugene Chudakov; Howard Fenker; Arne Freyberger; Douglas Higinbotham; Poelker, B.; Michael Steigerwald; Michael Tiefenback; Christian Cavata; Stephanie Escoffier; Frederic Marie; Thierry Pussieux; Pascal Vernin; Samuel Danagoulian; Kahanawita Dharmawardane; Renee Fatemi; Kyungseon Joo; Markus Zeier; Viktor Gorbenko; Rakhsha Nasseripour; Brian Raue; Riad Suleiman; Benedikt Zihlmann

2004-01-01

Precision measurements of the relative analyzing powers of five electron beam polarimeters, based on Compton, Moller, and Mott scattering, have been performed using the CEBAF accelerator at the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory). A Wien filter in the 100 keV beamline of the injector was used to vary the electron spin orientation exiting the injector. High statistical precision measurements of the scattering asymmetry as a function of the spin orientation were made with each polarimeter. Since each polarimeter receives beam with the same magnitude of polarization, these asymmetry measurements permit a high statistical precision comparison of the relative analyzing powers of the five polarimeters. This is the first time a precise comparison of the analyzing powers of Compton, Moller, and Mott scattering polarimeters has been made. Statistically significant disagreements among the values of the beam polarization calculated from the asymmetry measurements made with each polarimeter reveal either errors in the values of the analyzing power, or failure to correctly include all systematic effects. The measurements reported here represent a first step toward understanding the systematic effects of these electron polarimeters. Such studies are necessary to realize high absolute accuracy (ca. 1%) electron polarization measurements, as required for some parity violation measurements planned at Jefferson Laboratory. Finally, a comparison of the value of the spin orientation exiting the injector that provides maximum longitudinal polarization in each experimental hall leads to an independent and very precise (better than 10-4) absolute measurement of the final electron beam energy

On the regularities of gamma-ray initiated emission of really-secondary electrons

International Nuclear Information System (INIS)

Grudskij, M.Ya.; Roldugin, N.N.; Smirnov, V.V.

1982-01-01

Emission regularities of the really-secondary electrons from metals are discussed on the basis of experimental data on electron emission characteristics under gamma radiation of incident quanta produced for a wide energy range (Esub(γ)=0.03+-2 MeV) and atomic numbers of target materials (Z=13+-79). Comparison with published experimental and calculated data is performed. It is shown that yield of the really-secondary electrons into vacuum from the target surface bombarded with a normally incident collimated beam of gamma radiation calculating on energy unit absorbed in the yield zone of the really-secondary electrons is determined only with the target material emittivity and can be calculated if spatial-energy distributions and the number of secondary fast electrons emitted out of the target are known

A comparison of footprint indexes calculated from ink and electronic footprints.

Science.gov (United States)

Urry, S R; Wearing, S C

2001-04-01

Pressure platforms offer the potential to measure and record electronic footprints rapidly; however, the accuracy of geometric indexes derived from these prints has not been investigated. A comparison of conventional ink footprints with simultaneously acquired electronic prints revealed significant differences in several geometric indexes. The contact area was consistently underestimated by the electronic prints and resulted in a significant change in the arch index. The long plantar angle was poorly correlated between techniques. This study demonstrated that electronic footprints, derived from a pressure platform, are not representative of the equivalent ink footprints and, consequently, should not be interpreted with reference to literature on conventional footprints.

A Comparison of Response Rate, Response Time, and Costs of Mail and Electronic Surveys.

Science.gov (United States)

Shannon, David M.; Bradshaw, Carol C.

2002-01-01

Compared response rates, response time, and costs of mail and electronic surveys using a sample of 377 college faculty members. Mail surveys yielded a higher response rate and a lower rate of undeliverable surveys, but response time was longer and costs were higher than for electronic surveys. (SLD)

The photoneutron yield predictions by PICA and comparison with the measurements

International Nuclear Information System (INIS)

Job, P.K.; Gabriel, T.A.

1995-01-01

The photoneutron yields at higher photon energies have become very important since the advent of high energy electron accelerators. Bremsstrahlung is produced when the particle beam interacts with the storage-ring components or residual-gas molecules in the storage-ring vacuum. Bremsstrahlung thus produced interacts with the high-Z materials in the beamline like the beam dumps and collimators to produce photoneutrons. There are three modes of neutron production by bremsstrahlung. At low energies (≥525 MeV), photons are absorbed by the dipole interaction and the compound nucleus thus formed decays emitting protons and neutrons and other heavier particles. At higher energies (≥25 MeV), photon interacts with the nucleus through absorption on a quasi-deuteron, which subsequently decays producing a neutron and proton pair which can interact with the rest of the nucleus. At still higher energies the photopion production becomes possible and competes with the quasi-deuteron process. In this paper we have calculated the photoneutron yield from a thick copper target using the photonuclear interaction code PICA. Using this as the neutron source, we have calculated the dose rates through heavy concrete and compared it with the measurements made at the Advanced Photon Source at Argonne National Lab

submitter Measurement of LYSO Intrinsic Light Yield Using Electron Excitation

CERN Document Server

Martinez Turtos, Rosana; Pizzichemi, Marco; Ghezzi, Alessio; Pauwels, Kristof; Auffray, Etiennette; Lecoq, Paul; Paganoni, Marco

2016-01-01

The determination of the intrinsic light yield $(LY_{int})$ of scintillating crystals, i.e. number of optical photons created per amount of energy deposited, constitutes a key factor in order to characterize and optimize their energy and time resolution. However, until now measurements of this quantity are affected by large uncertainties and often rely on corrections for bulk absorption and surface/edge state. The novel idea presented in this contribution is based on the confinement of the scintillation emission in the central upper part of a 10 mm cubic crystal using a 1.5 MeV electron beam with diameter of 1 mm. A black non-reflective pinhole aligned with the excitation point is used to fix the light extraction solid angle (narrower than total reflection angle), which then sets a light cone travel path through the crystal. The final number of photoelectrons detected using a Hamamatsu R2059 photomultiplier tube (PMT) was corrected for the extraction solid angle, the Fresnel reflection coefficient and quantum...

A comparison of chemical and ionization dosimetry for high-energy x-ray and electron beams

International Nuclear Information System (INIS)

Durocher, J.J.; Boese, H.; Cormack, D.V.; Holloway, A.F.

1981-01-01

A comparison was made of ferrous sulfate (Fricke) and ionometric methods for determining the absorbed dose in a phantom irradiated with 4-MV x-rays, 25-MV x-rays, or electron beams having various incident energies between 10 and 32 MeV. Both chemical and ionization instruments were calibrated in a 60 Co beam at a point in water where the absorbed dose had been previously determined. The chemical yield measurements were corrected for spatial variations in dose within the volume of the solution and used to obtain a value of the absorbed dose for each of the x-ray and electron beams. The ratios of G-values required for these determinations were taken from ICRU reports 14 and 21. Ionization instrument readings from three types of commercial ionization chambers were used to obtain alternate values of the absorbed dose for each radiation. C lambda and CE values used in determining these ionization values of dose were also taken from the above ICRU reports. For 4-MV x-rays the values of absorbed dose obtained from chemical measurements agreed to within 0.5% with values obtained from ionization measurements; for 25-MV x-rays the chemical values were about 1% higher than the ionization values; for the electron beams the chemical values were 1%-4% below the ionization values. These discrepancies suggest an inconsistency among the recommended G, C lambda, and CE values similar to that which has been noted by other workers

Status of fission yield data

International Nuclear Information System (INIS)

England, T.R.; Blachot, J.

1988-01-01

In this paper we summarize the current status of the recent US evaluation for 34 fissioning nuclides at one or more neutron incident energies and for spontaneous fission. Currently there are 50 yields sets, and for each we have independent and cumulative yields and uncertainties for approximately 1100 fission products. When finalized the recommended data will become part of Version VI of the US ENDF/B. Other major evaluations in progress that are included in a recently formed IAEA Coordinated Research Program are also summarized. In a second part we review two empirical models in use to estimate independent yields. Comparison of model estimates with measured data is presented, including a comparison with some recent data obtained from Lohengrin (Cf-249 T). 18 refs., 13 figs., 3 tabs

Electron and ion temperatures: a comparison of ground-based incoherent scatter and AE-C satellite measurements

International Nuclear Information System (INIS)

Benson, R.F.; Bauer, P.; Brace, L.H.; Carlson, H.C.; Hagen, J.; Hanson, W.B.; Hoegy, W.R.; Torr, M.R.; Wickwar, V.B.

1977-01-01

The Atmosphere Exploere-C satellite (AE-C) is uniquely suited for correlative studies with ground-based stations because its on-board propulsion system enables a desired ground station overflight condition to be maintained for a period of several weeks. It also provides the first low-altitude (below 260 km) comparison of satellite and incoherent scatter electron and ion temperatures. More than 40 comparisons of remote and in situ measurements were made by using data from AE-C and four incoherent scatter stations (Arecibo, Chatanika, Millstone Hill, and St. Santin). The results indicate very good agreement between satellite and ground measurements of the ion temperature, the average satellite retarding potential analyzer temperatures differing from the average incoherent scatter temperatures by -2% at St. Santin, +3% at Millstone Hill, and +2% at Arecibo. The electron temperatures also agree well, the average satellite temperatures exceeding the average incoherent scatter temperatures by 3% at St. Santin, 2% at Arecibo, and 11% at Millstone Hill. Several temperature comparisons were made between AE-C and Chatanika. In spite of the highly variable ionosphere often encountered at this high-latitude location, good agreement was obtained between the in situ and remote measurements of electron and ion temperatures. Longitudinal variations are found to be very important in the comparisons of electron temperature in some locations. The agreement between the electron temperatures is considerably better than that found in some earlier comparisons involving satellities at higher altitudes

On novel mechanisms of slow ion induced electron emission

International Nuclear Information System (INIS)

Eder, H.

2000-09-01

The present work has contributed in new ways to the field of slow ion induced electron emission. First, measurements of the total electron yield γ for impact of slow singly and multiply charged ions on atomically clean polycrystalline gold and graphite have been made. The respective yields were determined by current measurements and measurements of the electron number statistics. A new mechanism for kinetic emission (KE) below the so called 'classical threshold' was found and discussed. For a given ion species and impact velocity a slight decrease of the yields was found for ion charge state q = 1 toward 3, but no significant differences in KE yields for higher q values. Comparison of the results from gold and graphite showed overall similar behavior, but for C+ a relatively strong difference was observed and ascribed to more effective electron promotion in the C-C- than in the C-Au system. Secondly, for the very specific system H0 on LiF we investigated single electron excitation processes under grazing incidence conditions. In this way long-range interactions of hydrogen atoms with the ionic crystal surface could be probed. Position- and velocity-dependent electron production rates were found which indicate that an electron promotion mechanism is responsible for the observed electron emission. Thirdly, in order to investigate the importance of plasmon excitation and -decay in slow ion induced electron emission, measurements of electron energy distributions from impact of singly and doubly charged ions on poly- and monocrystalline aluminum surfaces were performed. From the results we conclude that direct plasmon excitation by slow ions occurs due to the potential energy of the projectile in a quasi-resonant fashion. The highest relative plasmon intensities were found for impact of 5 keV Ne+ on Al(111) with 5 % of the total yield. For impact of H + and H 2 + characteristical differences were observed for Al(111) and polycrystalline aluminum. We show that

Free ion yield observed in liquid isooctane irradiated by γ rays. Comparison with the Onsager theory

International Nuclear Information System (INIS)

Pardo, J; Franco, L; Gomez, F; Iglesias, A; Lobato, R; Mosquera, J; Pazos, A; Pena, J; Pombar, M; RodrIguez, A; Sendon, J

2004-01-01

We have analysed data on the free ion yield observed in liquid isooctane irradiated by 60 Co γ rays within the framework of the Onsager theory about initial recombination. Several distribution functions describing the electron thermalization distance have been used and compared with the experimental results: a delta function, a Gaussian-type function and an exponential function. A linear dependence between the free ion yield and the external electric field has been found at low-electric-field values (E ≤ 1.2 x 10 3 V mm -1 ) in excellent agreement with the Onsager theory. At higher electric field values, we obtain a solution in power series of the external field using the Onsager theory

Free ion yield observed in liquid isooctane irradiated by {gamma} rays. Comparison with the Onsager theory

Energy Technology Data Exchange (ETDEWEB)

Pardo, J [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Franco, L [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Gomez, F [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Iglesias, A [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Lobato, R [Hospital ClInico Universitario de Santiago, Santiago de Compostela (Spain); Mosquera, J [Hospital ClInico Universitario de Santiago, Santiago de Compostela (Spain); Pazos, A [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Pena, J [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Pombar, M [Hospital ClInico Universitario de Santiago, Santiago de Compostela (Spain); RodrIguez, A [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Sendon, J [Hospital ClInico Universitario de Santiago, Santiago de Compostela (Spain)

2004-05-21

We have analysed data on the free ion yield observed in liquid isooctane irradiated by {sup 60}Co {gamma} rays within the framework of the Onsager theory about initial recombination. Several distribution functions describing the electron thermalization distance have been used and compared with the experimental results: a delta function, a Gaussian-type function and an exponential function. A linear dependence between the free ion yield and the external electric field has been found at low-electric-field values (E {<=} 1.2 x 10{sup 3} V mm{sup -1}) in excellent agreement with the Onsager theory. At higher electric field values, we obtain a solution in power series of the external field using the Onsager theory.

1D numerical simulation of charge trapping in an insulator submitted to an electron beam irradiation. Part I: Computation of the initial secondary electron emission yield

International Nuclear Information System (INIS)

Aoufi, A.; Damamme, G.

2011-01-01

The aim of this work is to study by numerical simulation a mathematical modelling technique describing charge trapping during initial charge injection in an insulator submitted to electron beam irradiation. A two-fluxes method described by a set of two stationary transport equations is used to split the electron current j e (z) into coupled forward j e+ (z) and backward j e (z) currents and such that j e (z) = j e+ (z) - j e- (z). The sparse algebraic linear system, resulting from the vertex-centered finite-volume discretization scheme is solved by an iterative decoupled fixed point method which involves the direct inversion of a bi-diagonal matrix. The sensitivity of the initial secondary electron emission yield with respect to the energy of incident primary electrons beam, that is penetration depth of the incident beam, or electron cross sections (absorption and diffusion) is investigated by numerical simulations. (authors)

Local conditions for the Pauli potential in order to yield self-consistent electron densities exhibiting proper atomic shell structure

Energy Technology Data Exchange (ETDEWEB)

Finzel, Kati, E-mail: kati.finzel@liu.se [Linköpings University, IFM Department of Physics, 58183 Linköping (Sweden)

2016-01-21

The local conditions for the Pauli potential that are necessary in order to yield self-consistent electron densities from orbital-free calculations are investigated for approximations that are expressed with the help of a local position variable. It is shown that those local conditions also apply when the Pauli potential is given in terms of the electron density. An explicit formula for the Ne atom is given, preserving the local conditions during the iterative procedure. The resulting orbital-free electron density exhibits proper shell structure behavior and is in close agreement with the Kohn-Sham electron density. This study demonstrates that it is possible to obtain self-consistent orbital-free electron densities with proper atomic shell structure from simple one-point approximations for the Pauli potential at local density level.

Multi-dimensional free-electron laser simulation codes: a comparison study

CERN Document Server

Biedron, S G; Dejus, Roger J; Faatz, B; Freund, H P; Milton, S V; Nuhn, H D; Reiche, S

2000-01-01

A self-amplified spontaneous emission (SASE) free-electron laser (FEL) is under construction at the Advanced Photon Source (APS). Five FEL simulation codes were used in the design phase: GENESIS, GINGER, MEDUSA, RON, and TDA3D. Initial comparisons between each of these independent formulations show good agreement for the parameters of the APS SASE FEL.

Multi-dimensional free-electron laser simulation codes: a comparison study

International Nuclear Information System (INIS)

Biedron, S. G.; Chae, Y. C.; Dejus, R. J.; Faatz, B.; Freund, H. P.; Milton, S. V.; Nuhn, H.-D.; Reiche, S.

1999-01-01

A self-amplified spontaneous emission (SASE) free-electron laser (FEL) is under construction at the Advanced Photon Source (APS). Five FEL simulation codes were used in the design phase: GENESIS, GINGER, MEDUSA, RON, and TDA3D. Initial comparisons between each of these independent formulations show good agreement for the parameters of the APS SASE FEL

Improved Electron Yield and Spin-Polarization from III-V Photocathodes via Bias Enhanced Carrier Drift: Final Report

International Nuclear Information System (INIS)

Mulhollan, Gregory A.

2006-01-01

In this DOE STTR program, Saxet Surface Science, with the Stanford Linear Accelerator Center as partner, designed, built and tested photocathode structures such that optimal drift-enhanced spin-polarization from GaAs based photoemitters was achieved with minimal bias supply requirements. The forward bias surface grid composition was optimized for maximum polarization and yield, together with other construction parameters including doping profile. This program has culminated in a cathode bias structure affording increased electron spin polarization when applied to III-V based photocathodes. The optimized bias structure has been incorporated into a cathode mounting and biasing design for use in a polarized electron gun.

Pulse radiolysis study on temperature and pressure dependence of the yield of solvated electron in methanol from room temperature to supercritical condition

International Nuclear Information System (INIS)

Han, Zhenhui; He, Hui; Lin, Mingzhang; Muroya, Yusa; Katsumura, Yosuke

2012-09-01

A new concept of nuclear reactor, supercritical water-cooled reactor (SCWR), has been proposed, which is based on the success of the use of supercritical water (SCW) in fossil fuel power plants for more than three decades. This new concept reactor has advantages of higher thermal conversion efficiency, simplicity in structure, safety, etc, and it has been selected as one of the reactor concepts for the next generation nuclear reactor systems. In these reactors, the same as in boiling water reactors (BWR) and pressurized water reactors (PWR), water is used not only as a coolant but also as a moderator. It is very important to understand the behavior of the radiolysis products of water under the supercritical condition, since the water is exposed to a strong radiation field under very high temperature condition. Usually, in order to predict the concentrations of water decomposition products with carrying out some kinds of computer simulations, knowledge of the temperature and/or pressure dependent G-values (denoting the experimentally measured radiolytic yields) as well as of the rate constants of a set of reactions becomes very important. Therefore, in recent years, two groups from Argonne National Laboratory and The University of Tokyo, simultaneously conducted two projects aimed at obtaining basic data on radiolysis of SCW. However, it is still lack of reliable radiolytic yields of water decomposition products in very high temperature region. As we known, the properties of solvated electrons in polar liquid are very helpful for our understanding how they play a central role in many processes, such as solvation and reducing reactions. The solvated electron can also be used as a probe to determine the dynamic nature of the polar liquid systems. Comparing to water, the primary alcohols have much milder critical points, for example, for water and methanol, the critical temperature and pressure are 374 deg. C and 22.1 MPa and 239.5 deg. C and 8.1 MPa, respectively

Comparison of thick-target (alpha,n yield calculation codes

Directory of Open Access Journals (Sweden)

Fernandes Ana C.

2017-01-01

Full Text Available Neutron production yields and energy distributions from (α,n reactions in light elements were calculated using three different codes (SOURCES, NEDIS and USD and compared with the existing experimental data in the 3.5-10 MeV alpha energy range. SOURCES and NEDIS display an agreement between calculated and measured yields in the decay series of 235U, 238U and 232Th within ±10% for most materials. The discrepancy increases with alpha energy but still an agreement of ±20% applies to all materials with reliable elemental production yields (the few exceptions are identified. The calculated neutron energy distributions describe the experimental data, with NEDIS retrieving very well the detailed features. USD generally underestimates the measured yields, in particular for compounds with heavy elements and/or at high alpha energies. The energy distributions exhibit sharp peaks that do not match the observations. These findings may be caused by a poor accounting of the alpha particle energy loss by the code. A big variability was found among the calculated neutron production yields for alphas from Sm decay; the lack of yield measurements for low (~2 MeV alphas does not allow to conclude on the codes’ accuracy in this energy region.

Comparison of n-γ discrimination by zero-crossing and digital charge comparison methods

International Nuclear Information System (INIS)

Wolski, D.; Moszynski, M.; Ludziejewski, T.; Johnson, A.; Klamra, W.; Skeppstedt, Oe.

1995-01-01

A comparative study of the n-γ discrimination done by the digital charge comparison and zero-crossing methods was carried out for a 130 mm in diameter and 130 mm high BC501A liquid scintillator coupled to a 130 mm diameter XP4512B photomultiplier. The high quality of the tested detector was reflected in a photoelectron yield of 2300±100 phe/MeV and excellent n-γ discrimination properties with energy discrimination thresholds corresponding to very low neutron (or electron) energies. The superiority of the Z/C method was demonstrated for the n-γ discrimination method alone, as well as, for the simultaneous separation by the pulse shape discrimination and the time-of-flight methods down to about 30 keV recoil electron energy. The digital charge comparison method fails for a large dynamic range of energy and its separation is weakly improved by time-of-flight method for low energies. (orig.)

Reduction of secondary electron yield for E-cloud mitigation by laser ablation surface engineering

Energy Technology Data Exchange (ETDEWEB)

Valizadeh, R., E-mail: reza.valizadeh@stfc.ac.uk [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Malyshev, O.B. [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Wang, S. [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Department of Physics, Loughborough University, Loughborough LE11 3TU (United Kingdom); Sian, T. [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); The Photon Science Institute, The University of Manchester, Manchester M13 9PL (United Kingdom); Cropper, M.D. [Department of Physics, Loughborough University, Loughborough LE11 3TU (United Kingdom); Sykes, N. [Micronanics Ltd., Didcot, Oxon OX11 0QX (United Kingdom)

2017-05-15

Highlights: • SEY below 1 can be achieved with Laser ablation surface engineering. • SEY <1 surface can be produced with different types of nanosecond lasers. • Both microstructure (groves) and nano-structures are playing a role in reducing SEY. - Abstract: Developing a surface with low Secondary Electron Yield (SEY) is one of the main ways of mitigating electron cloud and beam-induced electron multipacting in high-energy charged particle accelerators. In our previous publications, a low SEY < 0.9 for as-received metal surfaces modified by a nanosecond pulsed laser was reported. In this paper, the SEY of laser-treated blackened copper has been investigated as a function of different laser irradiation parameters. We explore and study the influence of micro- and nano-structures induced by laser surface treatment in air of copper samples as a function of various laser irradiation parameters such as peak power, laser wavelength (λ = 355 nm and 1064 nm), number of pulses per point (scan speed and repetition rate) and fluence, on the SEY. The surface chemical composition was determined by x-ray photoelectron spectroscopy (XPS) which revealed that heating resulted in diffusion of oxygen into the bulk and induced the transformation of CuO to sub-stoichiometric oxide. The surface topography was examined with high resolution scanning electron microscopy (HRSEM) which showed that the laser-treated surfaces are dominated by microstructure grooves and nanostructure features.

On the e-linac-based neutron yield

International Nuclear Information System (INIS)

Bunatyan, G.G.; Nikolenko, V.G.; Popov, A.B.

2010-01-01

We treat neutron generating in high atomic number materials due to the photonuclear reactions induced by the Bremsstrahlung of an electron beam produced by linear electron accelerator (e-linac). The dependence of neutron yield on the electron energy and the irradiated sample size is considered for various sample materials. The calculations are performed without resort to the so-called 'numerical Monte Carlo simulation'. The acquired neutron yields are well correlated with the data asserted in investigations performed at a number of the e-linac-driven neutron sources

Comparison of dose distribution for proton beams and electrons: advantages and disadvantages; Comparacao de distribuicao de dose para feixes de protons e eletrons: vantagens e desvantagens

Energy Technology Data Exchange (ETDEWEB)

Neto, Joao T.M.; Ferreira, Maira B.; Braga, Victor B. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil)

2016-07-01

This study consists of a simulation of cancer therapy using a beam of protons and electrons. By comparing dose distribution curves for both beams we have showed the advantages and disadvantages of both therapies. The study was performed with Monte Carlo simulations using Geant4 code for a brain tumor, and it was found that the presence of the Bragg peak in proton beam allows a higher dose deposition in tumor and protection of adjacent tissues, while the electron beam has an entry dose in the tissue higher than the proton, yielding to the tissue neighbors of the tumor, unnecessary radiation. Moreover, it was also found significant production of neutrons from the proton beam, showing its main disadvantage. The continuation of this work will add the comparison with clinical beams of photons. (author)

The Effect of Gas Ion Bombardment on the Secondary Electron Yield of TiN, TiCN and TiZrV Coatings For Suppressing Collective Electron Effects in Storage Rings

International Nuclear Information System (INIS)

Le Pimpec, F.; Kirby, R.E.; King, F.K.; Pivi, M.

2006-01-01

In many accelerator storage rings running positively charged beams, ionization of residual gas and secondary electron emission (SEE) in the beam pipe will give rise to an electron cloud which can cause beam blow-up or loss of the circulating beam. A preventative measure that suppresses electron cloud formation is to ensure that the vacuum wall has a low secondary emission yield (SEY). The SEY of thin films of TiN, sputter deposited Non-Evaporable Getters and a novel TiCN alloy were measured under a variety of conditions, including the effect of re-contamination from residual gas

Study of the yield of the Fricke dosimetry for electron energies from 2 to 90 MeV

International Nuclear Information System (INIS)

Berkvens, I.P.

1988-01-01

The chemical yield for the ferrous sulphate dosimeters was determined for 60 Co-γ radiation and for electron beams of mean energies in the points of measurements, between 2.7 and about 9 MeV. As references, absolute determinations of absorbed dose based on calorimetric measurements, were used. The irradiation geometry for the ferrous sulphate dosimeter differ always due to technical reasons somewhat from that for the absorber of the calorimeter. The investigators took this difference into account. Perturbation correction factors that correct for the difference in electron scattering in the air gaps around the absorber of the calorimeter and in the graphite, were computed with the Monte Carlo method. Also the ''reference volume method'' recently introduced by the ICRU (report No.35), was applied to correct for the introduction of a ferrous sulphate dosimeter in a graphite phantom. This correction is necessary as the electrons are stopped and scattered in a different way in graphite and water. The results indicated that there is no energy dependence of the chemical yield (G-value) of the dosimeter in the energy range 2.7 to about 9 MeV. A mean G-value of 1,584 (± 0.006) μ mol/J was obtained. For 60 Co-γ a G-value of 1.601 μ mol/J was determined. However, this difference might not be real but due to the present uncertainty in the stopping-power ratios graphite to water. These ratios are thus made use of to determine the G-value from measurements of the absorbed dose to graphite. Previous investigations, by the group from Gent, indicated a small increase of the G-value with the electron energy. These more accurate determinations thus instead indicate a constant G-value. Refs, figs, tabs

Electron Conditioning of Technical Aluminium Surfaces: Effect on the Secondary Electron Yield

Energy Technology Data Exchange (ETDEWEB)

Le Pimpec, F.

2004-12-13

The effect of electron conditioning on commercially aluminium alloys 1100 and 6063 were investigated. Contrary to the assumption that electron conditioning, if performed long enough, can reduce and stabilize the SEY to low values (< 1.3, value of many pure elements [1] ), the SEY of aluminium did not go lower than 1.8. In fact, it reincreases with continued electron exposure dose.

The electron beam characteristics of energies up to 20 MeV and comparison of electron parameters of linear accelerators

International Nuclear Information System (INIS)

Awada, M.; Elleithy, M.A.; ElWihady, G.F.; Mostafa, K.A.

2005-01-01

The electron beams characteristics studded for the energies 4-20 MeV of Varian 23 EX ,experimental results are presented and compared with the published data. The CADD curves are measured for all energies and carried out the PDD of different applicator sizes ,that compared with the PDD of in the BJR. The quality beam parameters are determined from the CADD curves and calculated the yielded parameters of the corresponding electron energies which compared with the published data of other accelerators and theoretical Monte-Carlo calculation. The beam profiles are measured at different depths to construct the isodose distribution

Electron energy distribution in a weakly ionized plasma

International Nuclear Information System (INIS)

Cesari, C.

1967-03-01

The aim of this work is to determine from both the theoretical and experimental points of view the type of distribution function for the electronic energies existing in a positive-column type cold laboratory plasma having an ionization rate of between 10 -6 and 10 -7 . The theoretical analysis, based on the imperfect Lorentz model and taking into account inelastic collisions is developed from the Boltzmann equation. The experimental method which we have employed for making an electrostatic analysis of the electronic energies makes use of a Langmuir probe used in conjunction with a transistorized electronic device. A comparison between the experimental and theoretical results yields information concerning the mechanisms governing electronic energy transfer on a microscopic scale. (author) [fr

Technological yields of sources for radiation processing

International Nuclear Information System (INIS)

Zagorski, Z.P.

1990-01-01

The present report is prepared for planners of radiation processing of any material. Sources with cobalt-60 are treated marginally, because most probably, there will be no installation of technically meaningful activity in Poland before the year 2000. Calculations are focused on accelerators of electrons, divided into two groups: versatile linacs of energy up to 13 MeV and accelerators of lower energy, below 2 MeV, of better energetical yield but of limited applications. The calculations are connected with the confrontation of the author's technological expectations during the preparation of the linac project in the late '60s, with the results of twenty years of exploitation of the machine. One has to realize that from the 150 kV input power from the mains, only 5 kV of bent and scanned beam is recovered on the conveyor. That power is only partially used for radiation induced phenomena, sometimes only a few percent, because of the demanded homogeneity of the dose, of the mode of packing of the object and its shape, of losses at the edges of the scanned area and in the spaces between boxes, and of losses during the dead time due to the tuning of the machine and dosimetric operations. The use of lower energy accelerators may be more economical in case of objects of optimum type. At the first stage, that is of the conversion of electrical power into that of the low energy electron beam, the yield is 2-3 times better than in the case of linacs. Attention has been paid to the technological aspects of electron beam conversion into the more penetrating bremsstrahlung similar to gamma radiation. The advantages of these technologies, which make it possible to control the shape of the processed object are stressed. Ten parameters necessary for a proper calculation of technological yields of radiation processing are listed. Additional conditions which must be taken into account in the comparison of the cost of radiation processing with the cost of other technologies are also

Diamond surface: atomic and electronic structure

International Nuclear Information System (INIS)

Pate, B.B.

1984-01-01

Experimental studies of the diamond surface (with primary emphasis on the (111) surface) are presented. Aspects of the diamond surface which are addressed include (1) the electronic structure, (2) the atomic structure, and (3) the effect of termination of the lattice by foreign atoms. Limited studies of graphite are discussed for comparison with the diamond results. Experimental results from valence band and core level photoemission spectroscopy (PES), Auger electron spectroscopy (AES), low energy electron diffraction (LEED), and carbon 1s near edge x-ray absorption fine structure (NEXAFS) spectroscopy (both the total electron yield (TEY) and Auger electron yield (AEY) techniques) are used to study and characterize both the clean and hydrogenated surface. In addition, the interaction of hydrogen with the diamond surface is examined using results from vibrational high resolution low energy electron loss spectroscopy (in collaboration with Waclawski, Pierce, Swanson, and Celotta at the National Bureau of Standards) and photon stimulated ion desorption (PSID) yield at photon energies near the carbon k-edge (hv greater than or equal to 280 eV). Both EELS and PSID verify that the mechanically polished 1 x 1 surface is hydrogen terminated and also that the reconstructed surface is hydrogen free. The (111) 2 x 2/2 x 1 reconstructed surface is obtained from the hydrogenated (111) 1 x 1:H surface by annealing to approx. = 1000 0 C. We observe occupied intrinsic surface states and a surface chemical shift (0.95 +- 0.1 eV) to lower binding energy of the carbon 1s level on the hydrogen-free reconstructed surface. Atomic hydrogen is found to be reactive with the reconstructed surface, while molecular hydrogen is relatively inert. Exposure of the reconstructed surface to atomic hydrogen results in chemisorption of hydrogen and removal of the intrinsic surface state emission in and near the band gap region

Experimental and theoretical studies on X-ray induced secondary electron yields in Ti and TiO2

International Nuclear Information System (INIS)

Iyasu, Takeshi; Tamura, Keiji; Shimizu, Ryuichi; Vlaicu, Mihai Aurel; Yoshikawa, Hideki

2006-01-01

Generation of X-ray induced secondary electrons in Ti and TiO 2 was studied from both experimental and theoretical approaches, using X-ray photoelectron spectroscopy (XPS) attached to a synchrotron radiation facility and Monte Carlo simulation, respectively. The experiment revealed that the yields of secondary electrons induced by X-rays (electrons/photon) at photon energies to 4950 and 5000eV for Ti and TiO 2 are δ Ti (4950eV)=0.002 and δ Ti (5000eV)=0.014 while those for TiO 2 are δ TiO 2 (4950eV)=0.003 and δ TiO 2 (5000eV)=0.018. A novel approach to obtain the escape depth of secondary electrons has been proposed and applied to Ti and TiO 2 . The approach agreed very well with the experimental data reported so far. The Monte Carlo simulation predicted; δ Ti * (4950eV)=0.002 and δ Ti * (5000eV)=0.011 while δ TiO 2 * (4950eV)=0.003 and δ TiO 2 * (5000eV)=0.015. An experimental examination on the contribution of X-ray induced secondary electrons to photocatalysis in TiO 2 has also been proposed

Deriving the coronal hole electron temperature: electron density dependent ionization / recombination considerations

International Nuclear Information System (INIS)

Doyle, John Gerard; Perez-Suarez, David; Singh, Avninda; Chapman, Steven; Bryans, Paul; Summers, Hugh; Savin, Daniel Wolf

2010-01-01

Comparison of appropriate theoretically derived line ratios with observational data can yield estimates of a plasma's physical parameters, such as electron density or temperature. The usual practice in the calculation of the line ratio is the assumption of excitation by electrons/protons followed by radiative decay. Furthermore, it is normal to use the so-called coronal approximation, i.e. one only considers ionization and recombination to and from the ground-state. A more accurate treatment is to include ionization/recombination to and from metastable levels. Here, we apply this to two lines from adjacent ionization stages, Mg IX 368 A and Mg X 625 A, which has been shown to be a very useful temperature diagnostic. At densities typical of coronal hole conditions, the difference between the electron temperature derived assuming the zero density limit compared with the electron density dependent ionization/recombination is small. This, however, is not the case for flares where the electron density is orders of magnitude larger. The derived temperature for the coronal hole at solar maximum is around 1.04 MK compared to just below 0.82 MK at solar minimum.

SU-E-T-210: Comparison of Proton with Electron Boost in Breast Cancer Treatment

Energy Technology Data Exchange (ETDEWEB)

Zheng, Y; Chang, A [Procure Proton Therapy Center, Oklahoma City, OK (United States); Liu, Y [INTEGRIS Cancer Institute of Oklahoma, Oklahoma City, OK (United States)

2015-06-15

Purpose: Electron beams are commonly used for boost radiation following whole breast irradiation (WBI) to improve the in-breast local control. Proton beams have a finite range and a sharper distal dose falloff compared to electron beams, thus potentially sparing more heart and lung in breast treatment. The purpose of the study is to compare protons with electrons for boost breast treatment in terms of target coverage and normal tissue sparing. Methods: Six breast cancer patients were included in this study. All women received WBI to 45–50 Gy, followed by a 10–16.2 Gy boost with standard fractionation. If proton beams were used for the boost treatment, an electron plan was retrospectively generated for comparison using the same CT set and structures, and vice versa if electron beams were used for treatment. Proton plans were generated using the treatment planning system (TPS) with two to three uniform scanning proton beams. Electron plans were generated using the Pinnacle TPS with one single en face beam. Dose-volume histograms (DVH) were calculated and compared between proton and electron boost plans. Results: Proton plans show a similar boost target coverage, similar skin dose, and much better heart and lung sparing. For an example patient, V95% for PTV was 99.98% and skin (5 mm shell) received a max dose close to the prescription dose for both protons and electrons; however, V2 and V5 for the ipsilateral lung and heart were 37.5%, 17.9% and 19.9%, 4.9% respectively for electrons, but were essentially 0 for protons. Conclusions: This dosimetric comparison demonstrates that while both proton therapy and electron therapy provided similar coverage and skin dose, proton therapy could largely reduce the dose to lung and heart, thus leading to potential less side effects.

Simulation of spring barley yield in different climatic zones of Northern and Central Europe. A comparison of nine crop models

Czech Academy of Sciences Publication Activity Database

Rötter, R.P.; Palosuo, T.; Kersebaum, K. C.; Angulo, C.; Bindi, M.; Ewert, F.; Ferrise, R.; Hlavinka, P.; Moriondo, M.; Nendel, C.; Olesen, J. E.; Patil, R. H.; Ruget, F.; Takáč, J.; Trnka, Miroslav

2012-01-01

Roč. 133, July 2012 (2012), s. 23-36 ISSN 0378-4290 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional research plan: CEZ:AV0Z60870520 Keywords : Climate * Crop growth simulation * Model comparison * Spring barley * Yield variability * Uncertainty Subject RIV: EH - Ecology, Behaviour Impact factor: 2.474, year: 2012

A re-evaluation of the initial yield of the hydrated electron in the picosecond time range

International Nuclear Information System (INIS)

Muroya, Yusa; Lin Mingzhang; Wu, Guozhong; Iijima, Hokuto; Yoshii, Koji; Ueda, Toru; Kudo, Hisaaki; Katsumura, Yosuke

2005-01-01

The yield of the hydrated electron in the picosecond time range has been re-evaluated with an ultrafast pulse radiolysis system using a laser photocathode RF-gun in combination with a conventional one, and a value of 4.1±0.2 per 100 eV of absorbed energy at 20 ps was derived. This is consistent with recent experimental results using a time correlation method [Bartels et al., J. Phys. Chem. A 104, 1686-1691 (2000)] and with Monte-Carlo calculations [Muroya et al., Can. J. Chem. 80 1367-1374 (2002)

Auscultation in flight: comparison of conventional and electronic stethoscopes.

Science.gov (United States)

Tourtier, J P; Libert, N; Clapson, P; Tazarourte, K; Borne, M; Grasser, L; Debien, B; Auroy, Y

2011-01-01

The ability to auscultate during air medical transport is compromised by high ambient-noise levels. The aim of this study was to assess the capabilities of a traditional and an electronic stethoscope (which is expected to amplify sounds and reduce ambient noise) to assess heart and breath sounds during medical transport in a Boeing C135. We tested one model of a traditional stethoscope (3MTM Littmann Cardiology IIITM) and one model of an electronic stethoscope (3MTM Littmann Stethoscope Model 3000). We studied heart and lung auscultation during real medical evacuations aboard a medically configured C135. For each device, the quality of auscultation was described using a visual rating scale (ranging from 0 to 100 mm, 0 corresponding to "I hear nothing," 100 to "I hear perfectly"). Comparisons were accomplished using a t-test for paired values. A total of 36 comparative evaluations were performed. For cardiac auscultation, the value of the visual rating scale was 53 ± 24 and 85 ± 11 mm, respectively, for the traditional and electronic stethoscope (paired t-test: P = .0024). For lung sounds, quality of auscultation was estimated at 27 ± 17 mm for traditional stethoscope and 68 ± 13 for electronic stethoscope (paired t-test: P = .0003). The electronic stethoscope was considered to be better than the standard model for hearing heart and lung sounds. Flight practitioners involved in air medical evacuation in the C135 aircraft are better able to practice auscultation with this electronic stethoscope than with a traditional one. Copyright © 2011 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved.

Determination of the Effective Detector Area of an Energy-Dispersive X-Ray Spectrometer at the Scanning Electron Microscope Using Experimental and Theoretical X-Ray Emission Yields.

Science.gov (United States)

Procop, Mathias; Hodoroaba, Vasile-Dan; Terborg, Ralf; Berger, Dirk

2016-12-01

A method is proposed to determine the effective detector area for energy-dispersive X-ray spectrometers (EDS). Nowadays, detectors are available for a wide range of nominal areas ranging from 10 up to 150 mm2. However, it remains in most cases unknown whether this nominal area coincides with the "net active sensor area" that should be given according to the related standard ISO 15632, or with any other area of the detector device. Moreover, the specific geometry of EDS installation may further reduce a given detector area. The proposed method can be applied to most scanning electron microscope/EDS configurations. The basic idea consists in a comparison of the measured count rate with the count rate resulting from known X-ray yields of copper, titanium, or silicon. The method was successfully tested on three detectors with known effective area and applied further to seven spectrometers from different manufacturers. In most cases the method gave an effective area smaller than the area given in the detector description.

Quantum yields and mechanism in TiO[sub 2] mediated photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Sun, Lizhong

1994-01-01

The photocatalytic pathway in TiO[sub 2] suspensions was examined using a spin trap/electron paramagnetic resonance spectroscopy technique within a competition kinetic scheme. Experimental results from competition reactions show that there is a marked difference in kinetic behaviors between the systems with (heterogeneous) and without (homogeneous) TiO[sub 2] suspension, confirming that the reaction pathway of OH- radicals in the TiO[sub 2] suspension is at least partly heterogeneous. A photocatalytic mechanism is proposed. A method of determining the trapping efficiency of OH- radicals was developed, using the spin trap DMPO (5,5-dimethyl-1-pyrroline N-oxide), for measuring growth rates of the spin adduct DMPO-OH and high pressure liquid chromatography for measuring the OH- radical generation rates. The reliability of the measurement method was confirmed by comparison with published values. The trapping efficiency in the heterogeneous (TiO[sub 2]) system was found to be ca 0.28. A method for quantum yield determinations in heterogeneous systems was developed, based on measurements of OH- radical generation rates and the flux of absorbed photons by TiO[sub 2] suspensions. A chemical actinometer was used to measure absorbed-photon flux. Good agreement with literature values was obtained for quantum yield measurements in p-benzoquinone and H[sub 2]O[sub 2] systems. Accordingly, the quantum yield of OH- radical generation in TiO[sub 2] suspensions was determined to be ca 0.040 at pH 7. Effects of suspension loading, light intensity, electron acceptor addition, and dissolved oxygen concentration on the quantum yield were observed. The effects of pH and buffer concentration on the formation rate of DMPO-OH spin adduct are discussed. 117 refs., 50 figs., 8 tabs.

LET dependence of scintillation yields in liquid argon

Energy Technology Data Exchange (ETDEWEB)

Doke, Tadayoshi; Hitachi, Akira; Kikuchi, Jun; Crawford, H J; Lindstrom, P J; Masuda, Kimiaki; Shibamura, Eido; Takahashi, Tan

1988-06-01

Scintillation yields (scintillation intensity per unit absorbed energy) in liquid argon for ionizing particles are reviewed as a function of LET for the particles. The maximum scintillation yield, which is obtained for relativistic heavy ions from Ne to La, is about 1.2 times larger than that for gamma rays in NaI(Tl) crystal. In the low LET region, the scintillation yields for relativistic electrons, protons and He ions are 10-20% lower than the maximum yield. This tendency can be explained by taking into account the existence of the electrons which have escaped from their parent ions. In the high LET region, a quenching effect due to high ionization density is observed for alpha particles, fission fragments and relativistic Au ions.

Study of the ionization of alkane-electron scavenger reactant mixtures irradiated by 60Co gamma rays

International Nuclear Information System (INIS)

Bonnet, Jacques.

1977-01-01

This study deals with ionization of alkane-electron scavenger reactant mixtures, irradiated by 60 Co γ-rays. It is shown that the extrapolated free-ion yields (extrapolated yield method) decrease with the reactant concentration. On the basis of ONSAGER model and theoretical treatment of MOZUMDER, the cross sections of epithermal electron attachment in hexane, cyclohexane, 2,2-dimethylbutane, cyclopentane, 2,2,4-trimethylpentane for CCl 4 , C 7 F 14 , C 6 H 5 Br, C 6 H 5 Cl, C 6 F 14 , (C 6 H 5 ) 2 are determined. A comparison between gas-phase and liquid-phase cross sections is established [fr

Comparisons between MCNP, EGS4 and experiment for clinical electron beams.

Science.gov (United States)

Jeraj, R; Keall, P J; Ostwald, P M

1999-03-01

Understanding the limitations of Monte Carlo codes is essential in order to avoid systematic errors in simulations, and to suggest further improvement of the codes. MCNP and EGS4, Monte Carlo codes commonly used in medical physics, were compared and evaluated against electron depth dose data and experimental backscatter results obtained using clinical radiotherapy beams. Different physical models and algorithms used in the codes give significantly different depth dose curves and electron backscattering factors. The default version of MCNP calculates electron depth dose curves which are too penetrating. The MCNP results agree better with experiment if the ITS-style energy-indexing algorithm is used. EGS4 underpredicts electron backscattering for high-Z materials. The results slightly improve if optimal PRESTA-I parameters are used. MCNP simulates backscattering well even for high-Z materials. To conclude the comparison, a timing study was performed. EGS4 is generally faster than MCNP and use of a large number of scoring voxels dramatically slows down the MCNP calculation. However, use of a large number of geometry voxels in MCNP only slightly affects the speed of the calculation.

Electron ejection from solids induced by fast highly-charged ions

Energy Technology Data Exchange (ETDEWEB)

Schiwietz, G. [Hahn-Meitner-Inst. GmbH, Berlin (Germany). Abt. FD; Xiao, G. [Hahn-Meitner-Inst. GmbH, Berlin (Germany). Abt. FD

1996-02-01

Total electron-ejection yields and Auger-electron spectra for highly-charged ions interacting with different foil targets have been investigated in this work. New experimental and theoretical data for normal incident 5 MeV/u heavy ions on graphite and polypropylene foils are presented and discussed. These two materials have been selected as model systems representing conductors and insulator targets. Our measured projectile nuclear-charge dependence of the total electron yield from carbon foils clearly deviates from results of some transport models that predict a proportionality with respect to the electronic stopping power of the projectiles. Possible reasons for this deviation are discussed. We have also extended our measurements on cascade-induced C-KLL Auger-electron production. The corresponding results for 5 MeV/u S ions on carbon were obtained with a new method and agree fairly well with previous data. Furthermore, we have performed an experimental and theoretical investigation on the nuclear-track potential in insulators. Comparison of experimental data with theoretical results for N{sup 7+}, Ne{sup 9+}, Ar{sup 16+} and Ni{sup 23+} ions allow for an estimate of the electron/hole pair recombination time at the center of the track in polypropylene. (orig.).

A novel comparison of Møller and Compton electron-beam polarimeters

Directory of Open Access Journals (Sweden)

J.A. Magee

2017-03-01

Full Text Available We have performed a novel comparison between electron-beam polarimeters based on Møller and Compton scattering. A sequence of electron-beam polarization measurements were performed at low beam currents (<5 μA during the Qweak experiment in Hall-C at Jefferson Lab. These low current measurements were bracketed by the regular high current (180 μA operation of the Compton polarimeter. All measurements were found to be consistent within experimental uncertainties of 1% or less, demonstrating that electron polarization does not depend significantly on the beam current. This result lends confidence to the common practice of applying Møller measurements made at low beam currents to physics experiments performed at higher beam currents. The agreement between two polarimetry techniques based on independent physical processes sets an important benchmark for future precision asymmetry measurements that require sub-1% precision in polarimetry.

Calculation of Bremsstrahlung yield for thin target

International Nuclear Information System (INIS)

Demir, N.; Akkurt, I.; Tekin, H. O.; Cakirli, R. B.; Akkus, B.; Kupa, I.

2010-01-01

The Bremsstrahlung photon is created by de-accelerating electron beam in an electric field which is usually a thin material so-called radiator. The obtained Bremsstrahlung yield depends on some parameter such as incoming electron beam energy, the thickness and also Z number of the radiator. The main aim of this work is to obtain optimum radiator to be used at Bremsstrahlung photon beam facility at TAC. For this purposes the Bremsstrahlung photon yield has been obtained using FLUKA code for different types materials.

Comparison of stability statistics for yield in barley (Hordeum vulgare ...

African Journals Online (AJOL)

STORAGESEVER

2010-03-15

Mar 15, 2010 ... statistics and yield indicated that only TOP method would be useful for simultaneously selecting for high yield and ... metric stability methods; i) they reduce the bias caused by outliers, ii) ...... Biometrics, 43: 45-53. Sabaghnia N ...

SU-E-T-05: Comparing DNA Strand Break Yields for Photons under Different Irradiation Conditions with Geant4-DNA.

Science.gov (United States)

Pater, P; Bernal, M; Naqa, I El; Seuntjens, J

2012-06-01

To validate and scrutinize published DNA strand break data with Geant4-DNA and a probabilistic model. To study the impact of source size, electronic equilibrium and secondary electron tracking cutoff on direct relative biological effectiveness (DRBE). Geant4 (v4.9.5) was used to simulate a cylindrical region of interest (ROI) with r = 15 nm and length = 1.05 mm, in a slab of liquid water of 1.06 g/cm 3 density. The ROI was irradiated with mono-energetic photons, with a uniformly distributed volumetric isotropic source (0.28, 1.5 keV) or a plane beam (0.662, 1.25 MeV), of variable size. Electrons were tracked down to 50 or 10 eV, with G4-DNA processes and energy transfer greater than 10.79 eV was scored. Based on volume ratios, each scored event had a 0.0388 probability of happening on either DNA helix (break). Clusters of at least one break on each DNA helix within 3.4 nm were found using a DBSCAN algorithm and categorized as double strand breaks (DSB). All other events were categorized as single strand breaks (SSB). Geant4-DNA is able to reproduce strand break yields previously published. Homogeneous irradiation conditions should be present throughout the ROI for DRBE comparisons. SSB yields seem slightly dependent on the primary photon energy. DRBEs show a significant increasing trend for lower energy incident photons. A lower electron cutoff produces higher SSB yields, but decreases the SSB/DSB yields ratio. The probabilistic and geometrical DNA models can predict equivalent results. Using Geant4, we were able to reproduce previously published results on the direct strand break yields of photon and study the importance of irradiation conditions. We also show an ascending trend for DRBE with lower incident photon energies. A probabilistic model coupled with track structure analysis can be used to simulate strand break yields. NSERC, CIHR. © 2012 American Association of Physicists in Medicine.

The unbearable lightness of "light" cigarettes: a comparison of smoke yields in six varieties of Canadian "light" cigarettes.

Science.gov (United States)

Gendreau, Paul L; Vitaro, Frank

2005-01-01

these varieties of cigarettes. Only yields of formaldehyde, crotonaldehyde, 1-aminonaphtalene, and proprionaldehyde were systematically reduced in all varieties of "light" cigarettes. The six varieties of "light" cigarettes examined in this study do not differ substantially from "regular" cigarettes in terms of smoke yields. We argue that the modified ISO protocol should be implemented for a more valid comparison of potential smoke yields in all varieties of cigarettes and that labelling based on this protocol should be promoted.

Free-ion yield for tetramethylsilane and tetramethylgermanium

International Nuclear Information System (INIS)

Hoshi, Y.; Higuchi, M.; Iso, H.; Sakamoto, M.; Ooyama, K.; Kikuchi, R.; Miyano, K.

1993-01-01

In high energy physics experiments, calorimeters are used to measure the total energy dissipated by the primary particles produced from high energy collisions. In one type of calorimeter, ionization chambers filled with liquid argon are used. The necessity of a cryostat in many cases prevents a compact chamber design. Hence, it is very desirable to have liquid ionization chambers operating at room temperature. From this view point, hydrocarbon liquids are intensively investigated as calorimeter media in high energy physics experiments. TMS and TMG are promising liquid materials because they have the properties of a large electron drift velocity and a large free-ion yield. The free-ion yield determines the sensitivity of the chamber and amplifier system to ionizing particles. Here, free-ion yields from 207 Bi conversion electrons were measured as a function of applied electric field in an ionization chamber filled with tetramethylsilane (TMS) or tetramethylgermanium (TMG), which were purified by simple methods. Also, the mean thermalization length of electrons liberated in the liquid was calculated by fitting a Gaussian form for the distribution function. The total free-ion yield and thermalization length in TMS and TMG were obtained to be 3.1 ± 0.3, 3.5 ± 0.2 and 191 ± 12 angstrom, respectively, including the impurity effect in liquid

Comparisons between MCNP, EGS4 and experiment for clinical electron beams

International Nuclear Information System (INIS)

Jeraj, R.; Keall, P.J.; Ostwald, P.M.

1999-01-01

Understanding the limitations of Monte Carlo codes is essential in order to avoid systematic errors in simulations, and to suggest further improvement of the codes. MCNP and EGS4, Monte Carlo codes commonly used in medical physics, were compared and evaluated against electron depth dose data and experimental backscatter results obtained using clinical radiotherapy beams. Different physical models and algorithms used in the codes give significantly different depth dose curves and electron backscattering factors. The default version of MCNP calculates electron depth dose curves which are too penetrating. The MCNP results agree better with experiment if the ITS-style energy-indexing algorithm is used. EGS4 underpredicts electron backscattering for high- Z materials. The results slightly improve if optimal PRESTA-I parameters are used. MCNP simulates backscattering well even for high- Z materials. To conclude the comparison, a timing study was performed. EGS4 is generally faster than MCNP and use of a large number of scoring voxels dramatically slows down the MCNP calculation. However, use of a large number of geometry voxels in MCNP only slightly affects the speed of the calculation. (author)

Yields of historical exploration programs

International Nuclear Information System (INIS)

Huslende, T.

1995-01-01

The paper relates to an method of evaluation developed for analysing the yield of historical exploration programs by computerized simulation. The most important elements show in coarse features how the results can be used in the different analyses. The evaluation is to be executed annually for the comparison and sorting of data from different offshore sites. Topics are exploration evaluation study, evaluation process, handling of exploration costs, discovered reserves, development projects, cash flow analysis, analysis of results, finding cost, international comparison. 1 ref., 11 figs

Analysis of the Photoneutron Yield and Thermal Neutron Flux in an Unreflected Electron Accelerator-Driven Neutron Source

International Nuclear Information System (INIS)

Dale, Gregory E.; Gahl, John M.

2005-01-01

There are several potential uses for a high-flux thermal neutron source in both industrial and clinical applications. The viable commercial implementation of these applications requires a low-cost, high-flux thermal neutron generator suitable for installation in industrial and clinical environments. This paper describes the Monte Carlo for N-Particle modeling results of a high-flux thermal neutron source driven with an electron accelerator. An electron linear accelerator (linac), fitted with a standard X-ray converter, can produce high neutron yields in materials with low photonuclear threshold energies, such as D and 9 Be. Results indicate that a 10-MeV, 10-kW electron linac can produce on the order of 10 12 n/s in a heavy water photoneutron target. The thermal neutron flux in an unreflected heavy water target is calculated to be on the order of 10 10 n.cm -2 .s. The sensitivity of these answers to heavy water purity is also investigated, specifically the dilution of heavy water with light water. It is shown that the peak thermal neutron flux is not adversely effected by dilution up to a light water weight fraction of 35%

Comparison of initial damage rates using neutron and electron irradiations

International Nuclear Information System (INIS)

Goldstone, J.A.R.

1978-08-01

The purpose of this experiment was twofold: (1) The number of interstitials that pin dislocations was studied as a function of neutron energy. (2) By comparison with electron irradiations on the sample, a correlation between the predicted and measured numbers of defects was found. All irradiations were performed on the same high purity copper sample. The sample was machined in the form of a cantilever beam with a flexural resonant frequency of 770 Hz. Changes in Young's modulus at constant strain amplitude were monitored continuously through changes in the resonant frequency of the sample. These changes in the modulus can be related to the number of pinning points added to dislocation lines, which are in turn related to the number of free interstitials produced. Neutron energy dependence experiments were done from 2 to 24 MeV on the copper sample and at 14 MeV on a gold sample. By equating pinning rates from electron and neutron irradiations and using the free interstitial production rate obtained from electron irradiations, an estimate of the free interstitial production cross section for neutrons of 2 to 24 MeV was made

Yield surface evolution for columnar ice

Science.gov (United States)

Zhou, Zhiwei; Ma, Wei; Zhang, Shujuan; Mu, Yanhu; Zhao, Shunpin; Li, Guoyu

A series of triaxial compression tests, which has capable of measuring the volumetric strain of the sample, were conducted on columnar ice. A new testing approach of probing the experimental yield surface was performed from a single sample in order to investigate yield and hardening behaviors of the columnar ice under complex stress states. Based on the characteristic of the volumetric strain, a new method of defined the multiaxial yield strengths of the columnar ice is proposed. The experimental yield surface remains elliptical shape in the stress space of effective stress versus mean stress. The effect of temperature, loading rate and loading path in the initial yield surface and deformation properties of the columnar ice were also studied. Subsequent yield surfaces of the columnar ice have been explored by using uniaxial and hydrostatic paths. The evolution of the subsequent yield surface exhibits significant path-dependent characteristics. The multiaxial hardening law of the columnar ice was established experimentally. A phenomenological yield criterion was presented for multiaxial yield and hardening behaviors of the columnar ice. The comparisons between the theoretical and measured results indicate that this current model is capable of giving a reasonable prediction for the multiaxial yield and post-yield properties of the columnar ice subjected to different temperature, loading rate and path conditions.

Comparison of dosimetric protocols to beamy of photons and electrons

Energy Technology Data Exchange (ETDEWEB)

Anglesio, S; Ragona, R; Cesana, P; Spandonari, T

1986-01-01

I+n this work different methods for the calculus of the absorbed dose at different photon and electron energies are utilized and the differences between their yields are evaluated. One of these methods is based on the consideration of the factors Csub(lambda) and Csub(E) (ICRU, HPA, AAPM protocols before 1980); by means of the others (AAPM-Task Group 21, NACP) we seek to obtain a better accuracy introducing new conversion factors. Our measurements were performed using cylindrical and flat ionisation chambers. In the considered energy range we obtained the following results: the new conversion factors have a higher avalue than Csub(lambda) and always smaller than Csub(E).

Comparison of macroscopic properties of electrons in plasmas of beam-plasma and glow discharges

International Nuclear Information System (INIS)

Winkler, R.; Wilhelm, J.; Starykh, V.V.

1979-01-01

The theoretical basis of the comparison are adequate Boltzmann equations for the electron component of the beam discharge plasma and the glow discharge plasma. We included the turbulent field or the direct electric field in the mentioned plasma types and all important binary collision processes as well as the Coulomb interaction between the charged particles. The comparison was performed in hydrogen under the condition of equal power input per volumen unit of both plasmas in dependence of the turbulence energy per one electron U, for the ionization degree (nsub(e)/N)sub(g) = 10 -6 and the pressure p 0 sup(g) = 1 Torr of the glow discharge plasma and for the ionization degrees (nsub(e)/N)sub(b) = 10 -3 , 10 -2 , 10 -1 and the pressure p 0 sup(b) = 10 -2 Torr of the beam discharge plasma which are typical for the existence of both plasma types. Based upon the numerical solutions of the Boltzmann equations under the mentioned additional conditions we compared the energy distribution functions of the electrons, the mean energy and the power losses of the electrons due to the different collision processes with the molecules and the ions. Especially a law for similarity of the electron kinetics of the two collision dominated plasma types was found and the main channels for the transfer of the field energy in both plasmas were determined. The results obtained were applied for assesing the perspectives of the beam discharged plasma as a plasmachemical reactor. (author)

Measurement of activity yields for 12C(#betta#, n)11C, 14N(#betta#, n)13N, and 16O(#betta#, n)15O reactions as a function of electron beam energy and angle from the electron beam using thick target produced bremsstrahlung

International Nuclear Information System (INIS)

Piltingsrud, H.V.

1983-01-01

The calculation of activity yields from practical photonuclear target systems designed to produce short-lived positron emitting radionuclides for nuclear medicine purposes requires certain basic information. These include a knowledge of the photon source (bremsstrahlung energy spectrum and intensity as a function of angle from the electron beam) and the #betta#, n activation cross section of the secondary target element. A lack of adequate information concerning these parameters motivated the present study in which activity yields for the reactions 12 C(#betta#, n) 11 C, 14 N(#betta#, n) 13 N, and 16 O(#betta#, n) 15 O were measured as a function of energy of and angle from the electron beam between 16 and 30 MeV and 0 0 and 30.5 0 , respectively. The data indicate highly complex relationships between the activity yield and the experimental variables. Also indicated are possible applications of the data to indicate the energy of an electron beam producing a given bremsstrahlung field in which activation measurements are made

The Activation of Non-evaporable Getters Monitored by AES, XPS, SSIMS and Secondary Electron Yield Measurements

CERN Document Server

Scheuerlein, C

2002-01-01

In this thesis the potential of the three classical surface analysis techniques Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SSIMS) for the characterisation of non-evaporable getter (NEG) materials is assessed and artefacts are described. The various NEG samples have been analysed in the context of the development of NEG thin film coatings for use in accelerator ultra high vacuum (UHV) systems. The secondary electron yield (SEY), which is a functional surface property of great importance for the application of NEG to accelerators, has been measured. The maximum SEY of an air exposed TiZr and TiZrV coating can be reduced from above 2.0 to below 1.1 during a 2 h heat treatment at 250 and 200 °C, respectively. Saturating an activated TiZrV surface in UHV increases the maximum SEY by about 0.1. Thus, in UHV the SEY of an activated NEG coating does not exceed the threshold value of 1.35, above which multipacting is predicted to occur in th...

A computer code package for Monte Carlo photon-electron transport simulation Comparisons with experimental benchmarks

International Nuclear Information System (INIS)

Popescu, Lucretiu M.

2000-01-01

A computer code package (PTSIM) for particle transport Monte Carlo simulation was developed using object oriented techniques of design and programming. A flexible system for simulation of coupled photon, electron transport, facilitating development of efficient simulation applications, was obtained. For photons: Compton and photo-electric effects, pair production and Rayleigh interactions are simulated, while for electrons, a class II condensed history scheme was considered, in which catastrophic interactions (Moeller electron-electron interaction, bremsstrahlung, etc.) are treated in detail and all other interactions with reduced individual effect on electron history are grouped together using continuous slowing down approximation and energy straggling theories. Electron angular straggling is simulated using Moliere theory or a mixed model in which scatters at large angles are treated as distinct events. Comparisons with experimentally benchmarks for electron transmission and bremsstrahlung emissions energy and angular spectra, and for dose calculations are presented

Pulsed electron-beam-sustained discharge in oxygen-containing gas mixtures: electrical characteristics, spectroscopy,and singlet oxygen yield

International Nuclear Information System (INIS)

Vagin, Nikolai P; Ionin, Andrei A; Klimachev, Yu M; Kotkov, A A; Podmar'kov, Yu P; Seleznev, L V; Sinitsyn, D V; Frolov, M P; Yuryshev, Nikolai N; Kochetov, Igor' V; Napartovich, A P; Hager, G D

2004-01-01

The electrical and spectroscopic characteristics of electron-beam-sustained discharge (EBSD) in oxygen and oxygen-containing gas mixtures are studied experimentally under gas pressures up to 100 Torr in a large excitation volume (∼18 L). It is shown that the EBSD in pure oxygen and its mixtures with inert gases is unstable and is characterised by a small specific energy contribution. The addition of small amounts (∼1%-10%) of carbon monoxide or hydrogen to oxygen or its mixtures with inert gases considerably improves the stability of the discharge, while the specific energy contribution W increases by more then an order of magnitude, achieving ∼6.5 kJ L -1 atm -1 per molecular component of the gas mixture. A part of the energy supplied to the EBSD is spent to excite vibrational levels of molecular additives. This was demonstrated experimentally by the initiation of a CO laser based on the O 2 : Ar : CO = 1 : 1 : 0.1 mixture. Experimental results on spectroscopy of the excited electronic states O 2 (a 1 Δ g ) and O 2 (b 1 Σ g + ), of oxygen formed in the EBSD are presented. A technique was worked out for measuring the concentration of singlet oxygen in the O 2 (a 1 Δ g ) state in the afterglow of the pulsed EBSD by comparing with the radiation intensity of singlet oxygen of a given concentration produced in a chemical generator. Preliminary measurements of the singlet-oxygen yield in the EBSD show that its value ∼3% for W ∼ 1.0 kJ L -1 atm -1 is in agreement with the theoretical estimate. Theoretical calculations performed for W ∼ 6.5 kJ L -1 atm -1 at a fixed temperature show that the singlet-oxygen yield may be ∼20%, which is higher than the value required to achieve the lasing threshold in an oxygen-iodine laser at room temperature. (laser applications and other topics in quantum electronics)

The secondary electron yield of TiZr and TiZrV non evaporable getter thin film coatings

CERN Document Server

Scheuerlein, C; Hilleret, Noël; Taborelli, M

2001-01-01

The secondary electron yield (SEY) of two different non evaporable getter (NEG) samples has been measured 'as received' and after thermal treatment. The investigated NEGs are TiZr and TiZrV thin film coatings of 1 mm thickness, which are sputter deposited onto copper substrates. The maximum SEY dmax of the air exposed TiZr and TiZrV coating decreases from above 2.0 to below 1.1 during a 2 hour heat treatment at 250 °C and 200 °C, respectively. Saturating an activated TiZrV surface under vacuum with the gases typically present in ultra high vacuum systems increases dmax by about 0.1. Changes in elemental surface composition during the applied heat treatments were monitored by Auger electron spectroscopy (AES). After activation carbon, oxygen and chlorine were detected on the NEG surfaces. The potential of AES for detecting the surface modifications which cause the reduction of SE emission during the applied heat treatments is critically discussed.

An analysis of the impact of native oxide, surface contamination and material density on total electron yield in the absence of surface charging effects

Energy Technology Data Exchange (ETDEWEB)

Iida, Susumu, E-mail: susumu.iida@toshiba.co.jp [EUVL Infrastructure Development Center, Inc., 16-1 Onogawa, Tsukuba-shi, Ibaraki-ken, 305-8569 (Japan); Ohya, Kaoru [Institute of Technology and Science, The University of Tokushima, 2-1 Minamijyousanjima-cho,Tokushima, 770-8506 (Japan); Hirano, Ryoichi; Watanabe, Hidehiro [EUVL Infrastructure Development Center, Inc., 16-1 Onogawa, Tsukuba-shi, Ibaraki-ken, 305-8569 (Japan)

2016-10-30

Highlights: • Total electron yields were assessed in the absence of any surface charging effect. • Experimental and simulation results showed a low native oxide energy barrier. • The yield enhancement effect of a native oxide layer was confirmed. • The yield enhancement effect of a thin surface contamination layer was confirmed. • Deviations in the material density from the theoretical values were evaluated. - Abstract: The effects of the presence of a native oxide film or surface contamination as well as variations in material density on the total electron yield (TEY) of Ru and B{sub 4}C were assessed in the absence of any surface charging effect. The experimental results were analyzed using semi-empirical Monte Carlo simulations and demonstrated that a native oxide film increased the TEY, and that this effect varied with film thickness. These phenomena were explained based on the effect of the backscattered electrons (BSEs) at the interface between Ru and RuO{sub 2}, as well as the lower potential barrier of RuO{sub 2}. Deviations in the material density from the theoretical values were attributed to the film deposition procedure based on fitting simulated TEY curves to experimental results. In the case of B{sub 4}C, the TEY was enhanced by the presence of a 0.8-nm-thick surface contamination film consisting of oxygenated hydrocarbons. The effect of the low potential barrier of the contamination film was found to be significant, as the density of the B{sub 4}C was much lower than that of the Ru. Comparing the simulation parameters generated in the present work with Joy’s database, it was found that the model and the input parameters used in the simulations were sufficiently accurate.

Impacts of varying agricultural intensification on crop yield and groundwater resources: comparison of the North China Plain and US High Plains

International Nuclear Information System (INIS)

Pei, Hongwei; Shen, Yanjun; Liu, Changming; Scanlon, Bridget R; Reedy, Robert C; Long, Di

2015-01-01

Agricultural intensification is often considered the primary approach to meet rising food demand. Here we compare impacts of intensive cultivation on crop yield in the North China Plain (NCP) with less intensive cultivation in the US High Plains (USHP) and associated effects on water resources using spatial datasets. Average crop yield during the past decade from intensive double cropping of wheat and corn in the NCP was only 15% higher than the yield from less intensive single cropping of corn in the USHP, although nitrogen fertilizer application and percent of cropland that was irrigated were both ∼2 times greater in the NCP than in the USHP. Irrigation and fertilization in both regions have depleted groundwater storage and resulted in widespread groundwater nitrate contamination. The limited response to intensive management in the NCP is attributed in part to the two month shorter growing season for corn to accommodate winter wheat than that for corn in the USHP. Previous field and modeling studies of crop yield in the NCP highlight over application of N and water resulting in low nitrogen and water use efficiencies and indicate that cultivars, plant densities, soil fertility and other factors had a much greater impact on crop yields over the past few decades. The NCP–USHP comparison along with previous field and modeling studies underscores the need to weigh the yield returns from intensive management relative to the negative impacts on water resources. Future crop management should consider the many factors that contribute to yield along with optimal fertilization and irrigation to further increase crop yields while reducing adverse impacts on water resources. (letter)

Project on comparison of structural parameters and electron density maps of oxalic acid dihydrate

NARCIS (Netherlands)

Coppens, Philip; Dam, J.; Harkema, Sybolt; Feil, D.

1984-01-01

Results obtained from four X-ray and five neutron data sets collected under a project sponsored by the Commission on Charge, Spin and Momentum Densities are analyzed by comparison of thermal parameters, positional parameters and X - N electron density maps. Three sets of theoretical calculations are

Effects of nitrogen application method and weed control on corn yield and yield components.

Science.gov (United States)

Sepahvand, Pariya; Sajedi, Nurali; Mousavi, Seyed Karim; Ghiasvand, Mohsen

2014-04-01

The effects of nitrogen fertilizer application and different methods for weed control on yield and yield components of corn was evaluated in Khorramabad in 2011. The experiment was conducted as a split plot based on randomized complete block design in 3 replications. Nitrogen application was as main plot in 4 levels (no nitrogen, broadcasting nitrogen, banding nitrogen and sprayed nitrogen) and methods of weed control were in 4 levels (non-control weeds, application Equip herbicide, once hand control of weeds and application Equip herbicide+once time weeding) was as subplots. Result illustrated that effects of nitrogen fertilizer application were significant on grain and forage yield, 100 seeds weight, harvest index, grain number per row and cob weight per plant. Grain yield increased by 91.4 and 3.9% in application banding and broadcasting for nitrogen fertilizer, respectively, compared to the no fertilizer treatment. The results show improved efficiency of nitrogen utilization by banding application. Grain yield, harvest index, seed rows per cob, seeds per row and cob weight were increased by weed control. In the application of Equip herbicide+ hand weeding treatment corn grain yield was increased 126% in comparison to weedy control. It represents of the intense affects of weed competition with corn. The highest corn grain yield (6758 kg h(-1)) was related to the application banding of nitrogen fertilizer and Equip herbicide+once hand weeding.

Comparison of decay and yield data between JNDC2 and ENDF/B-VI

Energy Technology Data Exchange (ETDEWEB)

Oyamatsu, K.; Sagosaka, M.; Miyazono, T. [Nagoya Univ. (Japan)

1997-03-01

This work is intended to be our first step to solve disagreements of the decay heat powers between measurements and summation calculations. We examine differences between nuclear data libraries to complement our uncertainty evaluation of the decay heat summation calculations only with ENDF/B-VI. The comparison is made mainly between JNDC2 and ENDF/B-VI while JEF2.2 decay data is also discussed. In this study, we propose and use a simple method which is an analogue of the overlap integral of two wave functions in quantum mechanics. As the first step, we compare the whole input nuclear data for the summation calculations as a whole. We find a slight difference of the fission yields especially for high-energy neutron induced fissions between JNDC2 and ENDF/B-VI. As for the decay energies, JNDC2, ENDF/B-VI are quite similar while JEF2.2 is found significantly different from these two libraries. We find substantial differences in the decay constant values among the three libraries. As the second step, we calculate the decay heat powers with FPGS90 using JNDC2 and ENDF/B-VI. The total decay heat powers with the two libraries differ by more than 10% at short cooling times while they agree well on the average at cooling times longer that 100 (s). We also point out nuclides whose contributions are significantly different between the two libraries even though the total decay heats agree well. These nuclides may cause some problems in predicting aggregate spectra of {beta} and {gamma} rays as well as delayed neutrons, and are to be reviewed in the future revision of decay and yield data. (author)

Electron temperature determination in LTE and non-LTE plasmas

International Nuclear Information System (INIS)

Eddy, T.L.

1983-01-01

This article discusses how most experimental investigations assume a type of ''thermal equilibrium'' in which the excited levels are assumed to be populated according to the electron kinetic temperature, in the determination of electron temperature in LTE and non-LTE plasmas. This is justified on the basis that electron collisions dominate the equilibration of adjacent excited levels as shown by Byron, Stabler and Boartz. The comparison of temperature values calculated by various common methods as a check for local thermodynamic equilibrium (LTDE) or local thermal equilibrium (LTE) of the upper excited levels and the free electrons has been shown to indicate the excitation temperature in all cases utilized. Thomas shows that the source function of the first excited level may be dominated by non-local radiation, which would usually result in a different population than local collisional excitation would provide. Ionization from upper levels is by collisional means. The result may yield different valued excitation and electron temperatures

Effects of high energy electrons on the properties of polyethylene / multiwalled carbon nanotubes composites: Comparison of as-grown and oxygen-functionalised MWCNT

International Nuclear Information System (INIS)

Krause, B.; Pötschke, P.; Gohs, U.

2014-01-01

Polymer modification with high energy electrons (EB) is well established in different applications for many years. It is used for crosslinking, curing, degrading, grafting of polymeric materials and polymerisation of monomers. In contrast to this traditional method, electron induced reactive processing (EIReP) combines the polymer modification with high energy electrons and the melt mixing process. This novel reactive method was used to prepare polymer blends and composites. In this study, both methods were used for the preparation of polyethylene (PE)/ multiwalled carbon nanotubes (MWCNT) composites in the presence of a coupling agent. The influence of MWCNT and type of electron treatment on the gel content, the thermal conductivity, rheological, and electrical properties was investigated whereby as-grown and oxidised MWCNT were used. In the presence of a coupling agent and at an absorbed dose of 40 kGy, the gel content increased from 57 % for the pure PE to 74 % or 88 % by the addition of as-grown (Baytubes® C150P) or oxidised MWCNT, respectively. In comparison to the composites containing the as-grown MWCNTs, the use of the oxidised MWCNTs led to higher melt viscosity and higher storage modulus due to higher yield of filler polymer couplings. The melt viscosity increased due to the addition of MWCNT and crosslinking of PE. The thermal conductivity increased to about 150 % and showed no dependence on the kind of MWCNT and the type of electron treatment. In contrast, the lowest value of electrical volume resistivity was found for the non-irradiated samples and after state of the art electron treatment without any influence of the type of MWCNT. In the case of EIReP, the volume resistivity increased by 2 (as-grown MWCNT) or 3 decades (oxidised MWCNT) depending on the process parameters

Modeling sediment yield in small catchments at event scale: Model comparison, development and evaluation

Science.gov (United States)

Tan, Z.; Leung, L. R.; Li, H. Y.; Tesfa, T. K.

2017-12-01

Sediment yield (SY) has significant impacts on river biogeochemistry and aquatic ecosystems but it is rarely represented in Earth System Models (ESMs). Existing SY models focus on estimating SY from large river basins or individual catchments so it is not clear how well they simulate SY in ESMs at larger spatial scales and globally. In this study, we compare the strengths and weaknesses of eight well-known SY models in simulating annual mean SY at about 400 small catchments ranging in size from 0.22 to 200 km2 in the US, Canada and Puerto Rico. In addition, we also investigate the performance of these models in simulating event-scale SY at six catchments in the US using high-quality hydrological inputs. The model comparison shows that none of the models can reproduce the SY at large spatial scales but the Morgan model performs the better than others despite its simplicity. In all model simulations, large underestimates occur in catchments with very high SY. A possible pathway to reduce the discrepancies is to incorporate sediment detachment by landsliding, which is currently not included in the models being evaluated. We propose a new SY model that is based on the Morgan model but including a landsliding soil detachment scheme that is being developed. Along with the results of the model comparison and evaluation, preliminary findings from the revised Morgan model will be presented.

Simulation of the molecular recombination yield for swift H2+ ions through thin carbon foils

International Nuclear Information System (INIS)

Garcia-Molina, Rafael; Barriga-Carrasco, Manuel D.

2003-01-01

We have calculated the recombination yield for swift H 2 + molecular ions at the exit of thin amorphous carbon foils, as a function of the dwell time and incident energy. Our results are based on a detailed simulation of the motion through the target of the H 2 + molecular ion (before dissociation takes place) and its constituent fragments (after dissociation), including the following effects: Coulomb repulsion, nuclear scattering, electron capture and loss, as well as self-retarding and wake forces, which provide the relative distance and velocity of the dissociated fragments at the foil exit. The recombination of an H 2 + ion at the exit of the foil depends on the interproton separation and internal energy of the dissociated fragments, and on their probability to capture an electron. Comparison of our results with the available experimental data shows a good agreement

First observation of Smith-Purcell radiation from relativistic electrons

International Nuclear Information System (INIS)

Doucas, G.; Mulvey, J.H.; Omori, M.; Walsh, J.; Kimmitt, M.F.

1992-01-01

A beam of 3.6 MeV electrons has been used to study the generation of radiation in far infra-red (FIR) by the Smith-Purcell mechanism. The dependence of wavelength on angle of emission, over angles from 56 deg to 150 deg and wavelengths from 350 μm to 1860 μm, is in excellent agreement with the Smith-Purcell dispersion relation. Comparison of the yield with that from a 5000 K source suggests that the spontaneous Smith-Purcell effect offers an easily tunable alternative to the synchrotron as a coherent FIR source, and could form the basis of a cheap, compact Free Electron Laser (FEL). (author) 6 refs.; 5 figs

Direct Signal-to-Noise Quality Comparison between an Electronic and Conventional Stethoscope aboard the International Space Station

Science.gov (United States)

Marshburn, Thomas; Cole, Richard; Ebert, Doug; Bauer, Pete

2014-01-01

Introduction: Evaluation of heart, lung, and bowel sounds is routinely performed with the use of a stethoscope to help detect a broad range of medical conditions. Stethoscope acquired information is even more valuable in a resource limited environments such as the International Space Station (ISS) where additional testing is not available. The high ambient noise level aboard the ISS poses a specific challenge to auscultation by stethoscope. An electronic stethoscope's ambient noise-reduction, greater sound amplification, recording capabilities, and sound visualization software may be an advantage to a conventional stethoscope in this environment. Methods: A single operator rated signal-to-noise quality from a conventional stethoscope (Littman 2218BE) and an electronic stethoscope (Litmann 3200). Borborygmi, pulmonic, and cardiac sound quality was ranked with both stethoscopes. Signal-to-noise rankings were preformed on a 1 to 10 subjective scale with 1 being inaudible, 6 the expected quality in an emergency department, 8 the expected quality in a clinic, and 10 the clearest possible quality. Testing took place in the Japanese Pressurized Module (JPM), Unity (Node 2), Destiny (US Lab), Tranquility (Node 3), and the Cupola of the International Space Station. All examinations were conducted at a single point in time. Results: The electronic stethoscope's performance ranked higher than the conventional stethoscope for each body sound in all modules tested. The electronic stethoscope's sound quality was rated between 7 and 10 in all modules tested. In comparison, the traditional stethoscope's sound quality was rated between 4 and 7. The signal to noise ratio of borborygmi showed the biggest difference between stethoscopes. In the modules tested, the auscultation of borborygmi was rated between 5 and 7 by the conventional stethoscope and consistently 10 by the electronic stethoscope. Discussion: This stethoscope comparison was limited to a single operator. However, we

Evaluation of yield and yield components and some agronomic traits of white bean genotypes under Karaj climate

Directory of Open Access Journals (Sweden)

M. Ebrahimi

2016-04-01

Full Text Available In order to study compatibility of 30 white bean genotypes under Karaj climate, an experiment was conducted based on randomized Complete Block Design with four replications. Evaluation and statistical analysis was performed for 18 important traits. Analysis of variance results showed that there are significant differences between varieties for all traits. Results of genotypes means comparison with Duncan’s multiple range test showed that genotype No. 29 was better than others in plant height, yield, and biological yield, seed no. per plant and pod weight traits. Simple correlation coefficients were significant between yield and weight of pod, biological yield, number of seed per plant, number of pod per plant, plant height, width of pod and number of seed per pod. Only pod length was negative correlated with yield between all investigated traits. Cluster analysis with UPGMA method arrangement genotypes into three groups. According to this experiment results we can recommend 29 and 30 genotypes for Karaj condition

Noise in secondary electron emission: the low yield case

Czech Academy of Sciences Publication Activity Database

Frank, Luděk

2005-01-01

Roč. 54, č. 4 (2005), s. 361-365 ISSN 0022-0744 R&D Projects: GA AV ČR(CZ) IAA1065304 Keywords : secondary electrons * noise * SEM image noise * secondary emission noise * statistics of secondary electrons * non-Poisson factor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.720, year: 2005

Comparison of thermal cracking and hydro-cracking yield distributions

Energy Technology Data Exchange (ETDEWEB)

Romero, S.; Sayles, S. [KBC Advanced Technologies Inc., Houston, TX (United States)

2009-07-01

Operators of bitumen upgraders are faced with the challenge of obtaining maximum performance from existing equipment whose performance is already pushed to the limits. The main constraint is the primary upgrader processes, notably coking and hydrocracking. Under the current economic conditions, funding for new equipment is difficult. However, changes can be made to optimize unit performance by better understanding the basic kinetics in thermal cracking and hydrocracking. This paper reviewed the yield distribution differences between thermal cracking and hydrocracking to provide insight into the basic components of operational changes. The objective was to compare yields, product quality distributions and the elemental balances. The opportunities to increase production and improve performance were then analyzed quantitatively within the existing unit equipment limits. tabs., figs.

Evidence for charge exchange effects in electronic excitations in Al by slow singly charged He ions

Energy Technology Data Exchange (ETDEWEB)

Riccardi, P., E-mail: Pierfrancesco.riccardi@fis.unical.it [Dipartimento di Fisica, Università della Calabria and INFN Gruppo collegato di Cosenza, Via P. Bucci cubo 31C, 87036 – Arcavacata di Rende, Cosenza (Italy); Sindona, A. [Dipartimento di Fisica, Università della Calabria and INFN Gruppo collegato di Cosenza, Via P. Bucci cubo 31C, 87036 – Arcavacata di Rende, Cosenza (Italy); Dukes, C.A. [Laboratory for Astrophysics and Surface Physics, Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States)

2016-09-01

We report on experiments of secondary electron emission in the interaction of helium ions with aluminum surfaces. Comparison between the electron emission induced by the impact of {sup 3}He{sup +} and {sup 4}He{sup +} on Al illustrates similarities and differences between the two projectiles. The intensity of emission shows the same dependence on velocity for the two isotopes, showing that KEE yields for helium ions impact on Al are dominated by direct excitation of valence electrons and not by electron promotion. Electron promotion and charge transfer processes are unambiguously identified by the observation of Auger electron emission from Al, at energies below the excitation threshold of Al–Al collisions, indicating energy losses for the projectiles higher than those commonly considered.

Electron emission from materials at low excitation energies

International Nuclear Information System (INIS)

Urma, N.; Kijek, M.; Millar, J.J.

1996-01-01

Full text: An experimental system has been designed and developed with the purpose of measuring the total electron emission yield from materials at low energy excitation. In the first instance the reliability of the system was checked by measuring the total electron emission yield for a well defined surface (aluminium 99.45%). The obtained data was in the expected range given by the literature, and consequently the system will be used further for measuring the total electron yield for a range of materials with interest in the instrumentation industry. We intend to measure the total electron emission yield under electron bombardment as a function of incident electron energy up to 1200 eV, angle of incidence, state of the surface and environment to which the surface has been exposed. Dependence of emission on total electron irradiated dose is also of interest. For many practical application of the 'Secondary Electron Emission', the total electron yield is desired to be as large as possible. The above phenomenon has practical applicability in electron multiplier tube and Scanning electron microscopy - when by means of the variation of the yield of the emitted electrons one may produce visible images of small sample areas. The electron multiplier tube, is a device which utilises the above effect to detect and amplify both single particles and low currents streams of charged particles. The majority of electron tubes use electrons with low energy, hundreds of eV. Not a lot has been published in the literature about this regime and also about the emission when the impinging electrons have small energy, up to 1 KeV. The information obtained from the experimental measurements concerning the total electron emission yield is used to asses the investigated materials as a potential electron emitting surfaces or dynodes in an electron multiplier tube

Measurements of beryllium sputtering yields at JET

Science.gov (United States)

Jet-Efda Contributors Stamp, M. F.; Krieger, K.; Brezinsek, S.

2011-08-01

The lifetime of the beryllium first wall in ITER will depend on erosion and redeposition processes. The physical sputtering yields for beryllium (both deuterium on beryllium (Be) and Be on Be) are of crucial importance since they drive the erosion process. Literature values of experimental sputtering yields show an order of magnitude variation so predictive modelling of ITER wall lifetimes has large uncertainty. We have reviewed the old beryllium yield experiments on JET and used current beryllium atomic data to produce revised beryllium sputtering yields. These experimental measurements have been compared with a simple physical sputtering model based on TRIM.SP beryllium yield data. Fair agreement is seen for beryllium yields from a clean beryllium limiter. However the yield on a beryllium divertor tile (with C/Be co-deposits) shows poor agreement at low electron temperatures indicating that the effect of the higher sputtering threshold for beryllium carbide is important.

Comparison of AC electronic monitoring and field data for estimating tolerance to Empoasca kraemeri (Homoptera: Cicadellidae) in common bean genotypes.

Science.gov (United States)

Serrano, M S; Backus, E A; Cardona, C

2000-12-01

Two methods for estimating the tolerance of common bean genotypes to Empoasca kraemeri Ross & Moore were compared, using a yield trial carried out at Centro Internacional de Agricultura Tropical (CIAT), Cali, Colombia, versus stylet penetration tactics measured by AC electronic feeding monitors. A stylet penetration index was devised based on principal component scores of three penetration tactics identified (pulsing laceration, cell rupturing, and lancing sap ingestion), combined with knowledge of the hopperburn symptoms caused by each tactic. Tolerant genotypes, as classified by the CIAT yield index, showed significantly more unprotected yield and lower hopperburn scores than the susceptible control. They also induced performance of less pulsing laceration (the tactic considered most damaging to the plant), and more of the other two, mitigating tactics, especially cell rupturing. When index values were calculated for each genotype, stylet penetration index values matched those of the yield index for three out of five genotypes: two EMP-coded tolerant lines ('EMP 385' and 'EMP 392') and the susceptible control 'BAT 41'. Thus, for these three genotypes, all subsequent hoppereburn symptoms are predictable by the type of feeding behavior performed on them. 'Porrillo Sintético' and 'EMP 84', considered borderline genotypes by the yield index, were overestimated and underestimated respectively, by the stylet penetration index. We postulate that, for these two genotypes, plant physiological responses to feeding (either compensatory or heightened sensitivity, respectively) synergize with type of feeding performed to generate the overall hopperburn condition. This multivariate analysis of electronic monitoring data was successfully used to devise an index of resistance. The implications of using the stylet penetration index and the advantages of using electronic monitoring in a bean-breeding program are discussed.

Bremsstrahlung spectra from thick-target electron beams with noncollisional energy losses

International Nuclear Information System (INIS)

Brown, J.C.; MacKinnon, A.L.

1985-01-01

We consider what can be learned from the bremsstrahlung radiation of fast electrons in a thick target, generalized to include electron energy losses additional to collisions. We show that the observed photon spectrum can, in principle, be inverted to yield an integral functional of the electron spectrum and the effective energy loss rate. In the light of this result, there seems no reason to suppose, in the absence of a priori information to the contrary, that the photon spectrum is symptomatic more of the fast electron distribution than of the energy loss processes. In cases where the electron injection spectrum is known on independent observational or theoretical grounds, it is possible to infer an effective, ''phenomenological'' energy loss function. In the more general case, however, fullest possible modeling of the physical situation and comparison of the resulting spectrum with observations is all that can be attempted

Secondary electron emission from metals and semi-conductor compounds

International Nuclear Information System (INIS)

Ono, Susumu; Kanaya, Koichi

1979-01-01

Attempt was made to present the sufficient solution of the secondary electron yield of metals and semiconductor compounds except insulators, applying the free electron scattering theory to the absorption of secondary electrons generated within a solid target. The paper is divided into the sections describing absorption coefficient and escape depth, quantitative characteristics of secondary yield, angular distribution of secondary electron emission, effect of incident angle to secondary yield, secondary electron yield transmitted, and lateral distribution of secondary electron emission, besides introduction and conclusion. The conclusions are as follows. Based on the exponential power law for screened atomic potential, secondary electron emission due to both primary and backscattered electrons penetrating into metallic elements and semi-conductive compounds is expressed in terms of the ionization loss in the first collision for escaping secondary electrons. The maximum yield and the corresponding primary energy can both consistently be derived as the functions of three parameters: atomic number, first ionization energy and backscattering coefficient. The yield-energy curve as a function of the incident energy and the backscattering coefficient is in good agreement with the experimental results. The energy dependence of the yield in thin films and the lateral distribution of secondary yield are derived as the functions of the backscattering coefficient and the primary energy. (Wakatsuki, Y.)

Single electron yields from semileptonic charm and bottom hadron decays in Au +Au collisions at √{sN N}=200 GeV

Science.gov (United States)

Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Alexander, J.; Alfred, M.; Aoki, K.; Apadula, N.; Aramaki, Y.; Asano, H.; Aschenauer, E. C.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bandara, N. S.; Bannier, B.; Barish, K. N.; Bassalleck, B.; Bathe, S.; Baublis, V.; Baumgart, S.; Bazilevsky, A.; Beaumier, M.; Beckman, S.; Belmont, R.; Berdnikov, A.; Berdnikov, Y.; Black, D.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Bryslawskyj, J.; Buesching, H.; Bumazhnov, V.; Butsyk, S.; Campbell, S.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choi, S.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Connors, M.; Cronin, N.; Crossette, N.; Csanád, M.; Csörgő, T.; Dairaku, S.; Danley, T. W.; Datta, A.; Daugherity, M. S.; David, G.; Deblasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dietzsch, O.; Ding, L.; Dion, A.; Diss, P. B.; Do, J. H.; Donadelli, M.; D'Orazio, L.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Edwards, S.; Efremenko, Y. V.; Engelmore, T.; Enokizono, A.; Esumi, S.; Eyser, K. O.; Fadem, B.; Feege, N.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Fusayasu, T.; Gainey, K.; Gal, C.; Gallus, P.; Garg, P.; Garishvili, A.; Garishvili, I.; Ge, H.; Giordano, F.; Glenn, A.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gu, Y.; Gunji, T.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamilton, H. F.; Han, S. Y.; Hanks, J.; Hasegawa, S.; Haseler, T. O. S.; Hashimoto, K.; Hayano, R.; Hayashi, S.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Homma, K.; Hong, B.; Horaguchi, T.; Hoshino, T.; Hotvedt, N.; Huang, J.; Huang, S.; Ichihara, T.; Iinuma, H.; Ikeda, Y.; Imai, K.; Imazu, Y.; Imrek, J.; Inaba, M.; Iordanova, A.; Isenhower, D.; Isinhue, A.; Ivanishchev, D.; Jacak, B. V.; Javani, M.; Jezghani, M.; Jia, J.; Jiang, X.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kamin, J.; Kanda, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Karatsu, K.; Kawall, D.; Kazantsev, A. V.; Kempel, T.; Key, J. A.; Khachatryan, V.; Khandai, P. K.; Khanzadeev, A.; Kijima, K. M.; Kim, B. I.; Kim, C.; Kim, D. J.; Kim, E.-J.; Kim, G. W.; Kim, M.; Kim, Y.-J.; Kim, Y. K.; Kimelman, B.; Kinney, E.; Kistenev, E.; Kitamura, R.; Klatsky, J.; Kleinjan, D.; Kline, P.; Koblesky, T.; Komkov, B.; Koster, J.; Kotchetkov, D.; Kotov, D.; Krizek, F.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S.; Lee, S. H.; Lee, S. R.; Leitch, M. J.; Leite, M. A. L.; Leitgab, M.; Lewis, B.; Li, X.; Lim, S. H.; Linden Levy, L. A.; Liu, M. X.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Makek, M.; Manion, A.; Manko, V. I.; Mannel, E.; Maruyama, T.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Meles, A.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Midori, J.; Mignerey, A. C.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Miyasaka, S.; Mizuno, S.; Mohanty, A. K.; Mohapatra, S.; Montuenga, P.; Moon, H. J.; Moon, T.; Morrison, D. P.; Moskowitz, M.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Mwai, A.; Nagae, T.; Nagamiya, S.; Nagashima, K.; Nagle, J. L.; Nagy, M. I.; Nakagawa, I.; Nakagomi, H.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nattrass, C.; Netrakanti, P. K.; Nihashi, M.; Niida, T.; Nishimura, S.; Nouicer, R.; Novák, T.; Novitzky, N.; Nukariya, A.; Nyanin, A. S.; Obayashi, H.; O'Brien, E.; Ogilvie, C. A.; Okada, K.; Orjuela Koop, J. D.; Osborn, J. D.; Oskarsson, A.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, J. S.; Park, S.; Park, S. K.; Pate, S. F.; Patel, L.; Patel, M.; Pei, H.; Peng, J.-C.; Perepelitsa, D. V.; Perera, G. D. N.; Peressounko, D. Yu.; Perry, J.; Petti, R.; Pinkenburg, C.; Pinson, R.; Pisani, R. P.; Purschke, M. L.; Qu, H.; Rak, J.; Ramson, B. J.; Ravinovich, I.; Read, K. F.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richardson, E.; Rinn, T.; Riveli, N.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rowan, Z.; Rubin, J. G.; Ryu, M. S.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sako, H.; Samsonov, V.; Sarsour, M.; Sato, S.; Sawada, S.; Schaefer, B.; Schmoll, B. K.; Sedgwick, K.; Seidl, R.; Sen, A.; Seto, R.; Sett, P.; Sexton, A.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Skolnik, M.; Slunečka, M.; Snowball, M.; Solano, S.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Steinberg, P.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sumita, T.; Sun, J.; Sziklai, J.; Takagui, E. M.; Takahara, A.; Taketani, A.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Tieulent, R.; Timilsina, A.; Todoroki, T.; Tomášek, M.; Torii, H.; Towell, C. L.; Towell, R.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Vale, C.; van Hecke, H. W.; Vargyas, M.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Virius, M.; Voas, B.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Whitaker, S.; White, A. S.; White, S. N.; Winter, D.; Wolin, S.; Woody, C. L.; Wysocki, M.; Xia, B.; Xue, L.; Yalcin, S.; Yamaguchi, Y. L.; Yanovich, A.; Ying, J.; Yokkaichi, S.; Yoo, J. H.; Yoon, I.; You, Z.; Younus, I.; Yu, H.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zhou, S.; Zou, L.; Phenix Collaboration

2016-03-01

The PHENIX Collaboration at the Relativistic Heavy Ion Collider has measured open heavy flavor production in minimum bias Au +Au collisions at √{sN N}=200 GeV via the yields of electrons from semileptonic decays of charm and bottom hadrons. Previous heavy flavor electron measurements indicated substantial modification in the momentum distribution of the parent heavy quarks owing to the quark-gluon plasma created in these collisions. For the first time, using the PHENIX silicon vertex detector to measure precision displaced tracking, the relative contributions from charm and bottom hadrons to these electrons as a function of transverse momentum are measured in Au +Au collisions. We compare the fraction of electrons from bottom hadrons to previously published results extracted from electron-hadron correlations in p +p collisions at √{sN N}=200 GeV and find the fractions to be similar within the large uncertainties on both measurements for pT>4 GeV/c . We use the bottom electron fractions in Au +Au and p +p along with the previously measured heavy flavor electron RA A to calculate the RA A for electrons from charm and bottom hadron decays separately. We find that electrons from bottom hadron decays are less suppressed than those from charm for the region 3

Study on the Secondary Electron Yield γ of Insulator for PDP Cathode

Science.gov (United States)

Motoyama, Y.; Ushirozawa, M.; Matsuzaki, H.; Takano, Y.; Seki, M.

1999-10-01

The secondary electron yield γ of the Plasma Display Panel (PDP) cathode is an important research object because it is closely related to the discharge voltages etc. For metal cathodes, we made a comprehensive examination^1 of γ for all rare gas ions and metastables according to Hagstrum's theory.^2 For γ of MgO, which is the useful insulator cathode, Aboelfotoh et al.^3 calculated the values for Ne and Ar ions supposing a monochrome PDP. However, the values of γ for other rare gas ions and their metastables necessary for a full color PDP have not yet been calculated. These values are calculated in the present study after them. The results are as follows: For ions, He:0.481 and Kr,Xe:0, assuming that there are no impurity levels in MgO; For metastables, He:0.491, Ne:0.489, Ar:0.428, Kr:0.381, and Xe:0.214. These results should serve as useful parameters in discharge simulation for the PDP. ^1H. Matsuzaki: Trans. IEE Jpn., 111-A, 971 (1991). ^2H.D. Hagstrum: Phys. Rev., 96, 336 (1954), ibid., 122, 83 (1961). ^3M.O. Aboelfotoh and J.A. Lorenzen: J. Appl. Phys., 48, 4754 (1977).

Study of inner-shell excitation processes from N(1s) orbitals in N{sub 2}O molecules by electron impact

Energy Technology Data Exchange (ETDEWEB)

Michelin, S E [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Arretche, F [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Mazon, K T [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Piacentini, J J [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Marin, A [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Oliveira, H L [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Travessini, D [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Lee, M-T [Departamento de Quimica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, SP (Brazil); Iga, I [Departamento de Quimica, Universidade Federal de Sao Carlos, 13565-905 Sao Carlos, SP (Brazil); Fujimoto, M M [Departamento de Fisica, Universidade Federal do Parana, 81531-990 Curitiba, PR (Brazil)

2007-11-28

A combination of the iterative Schwinger variational method with the distorted-wave approximation is applied to study excitations of a core-level electron in a triatomic molecule by electron impact. More specifically, we report calculated differential and integral cross sections for the X{sup 1}{sigma}{sup +} {yields} {sup 1,3}{pi}(2{sigma} {yields} 3{pi}) and X{sup 1}{sigma}{sup +} {yields} {sup 1,3}{pi}(3{sigma} {yields} 3{pi}) transitions in N{sub 2}O in the 415-900 eV incident energy range. The RI(1:3) ratios, obtained via dividing the distorted-wave integral cross sections for transitions leading to the singlet core-excited states by those leading to triplet states, are also reported. The generalized oscillator-strength profiles for the singlet transitions have also been calculated at the incident energy of 3400 eV. The comparison of these quantities with the available theoretical and experimental data reported in the literature is encouraging.

Evaluation of alanine as a reference dosimeter for therapy level dose comparisons in megavoltage electron beams

International Nuclear Information System (INIS)

McEwen, Malcolm; Sharpe, Peter; Voros, Sandor

2015-01-01

When comparing absorbed dose standards from different laboratories (e.g. National Measurement Institutes, NMIs, for Key or Supplementary comparisons) it is rarely possible to carry out a direct comparison of primary standard instruments, and therefore some form of transfer detector is required. Historically, air-filled, unsealed ionization chambers have been used because of the long history of using these instruments, very good stability over many years, and ease of transport. However, the use of ion chambers for therapy-level comparisons is not without its problems. Findings from recent investigations suggest that ion chambers are prone to non-random variations, they are not completely robust to standard courier practices, and failure at any step in a comparison can render all measurements potentially useless. An alternative approach is to identify a transfer system that is insensitive to some of these concerns - effectively a dosimeter that is inexpensive, simple to use, robust, but with sufficient precision and of a size relevant to the disseminated quantity in question. The alanine dosimetry system has been successfully used in a number of situations as an audit dosimeter and therefore the purpose of this investigation was to determine whether alanine could also be used as the transfer detector for dosimetric comparisons, which require a lower value for the measurement uncertainty. A measurement protocol was developed for comparing primary standards of absorbed dose to water in high-energy electron beams using alanine pellets irradiated in a water-equivalent plastic phantom. A trial comparison has been carried out between three NMIs and has indicated that alanine is a suitable alternative to ion chambers, with the system used achieving a precision of 0.1%. Although the focus of the evaluation was on the performance of the dosimeter, the comparison results are encouraging, showing agreement at the level of the combined uncertainties (∼0.6%). Based on this

Study of Coulomb effects using the comparison of positrons and electrons elastic scattering on nuclei

International Nuclear Information System (INIS)

Breton, Vincent

1990-01-01

We have studied Coulomb effects in the electron-nucleus interaction by measuring electron and positron elastic scattering. The Coulomb field of the nucleus acts differently on theses particles because of their opposite charges. The experiment took place at the Accelerateur Lineaire de Saclay, with 450 MeV electrons and positrons. We measured the emittance of the positron and electron beams. We compared electron and positron beams having the same energy, the same emittance and the same intensity. This way, we measured positron scattering cross sections with 2 % systematic error. By comparing positron and electron elastic scattering cross sections for momentum transfers between 1 and 2 fm -1 , on a Lead 208 target, we showed that the calculations of Coulomb effects in elastic scattering are in perfect agreement with experimental results. The comparison of positron and electron elastic scattering cross sections on Carbon showed that dispersive effects are smaller than 2 % outside the diffraction minima. These two results demonstrate in a definitive way that electron scattering allows to measure charge densities in the center of nuclei with an accuracy of the order of 1 %. (author) [fr

Oblique incidence of electron beams - comparisons between calculated and measured dose distributions

International Nuclear Information System (INIS)

Karcher, J.; Paulsen, F.; Christ, G.

2005-01-01

Clinical applications of high-energy electron beams, for example for the irradiation of internal mammary lymph nodes, can lead to oblique incidence of the beams. It is well known that oblique incidence of electron beams can alter the depth dose distribution as well as the specific dose per monitor unit. The dose per monitor unit is the absorbed dose in a point of interest of a beam, which is reached with a specific dose monitor value (DIN 6814-8[5]). Dose distribution and dose per monitor unit at oblique incidence were measured with a small-volume thimble chamber in a water phantom, and compared to both normal incidence and calculations of the Helax TMS 6.1 treatment planning system. At 4 MeV and 60 degrees, the maximum measured dose per monitor unit at oblique incidence was decreased up to 11%, whereas at 18MeV and 60 degrees this was increased up to 15% compared to normal incidence. Comparisons of measured and calculated dose distributions showed that the predicted dose at shallow depths is usually higher than the measured one, whereas it is smaller at depths beyond the depth of maximum dose. On the basis of the results of these comparisons, normalization depths and correction factors for the dose monitor value were suggested to correct the calculations of the dose per monitor unit. (orig.)

Determination of the antiproton-to-electron mass ratio by precision laser spectroscopy of $\\overline{p}He^{+}$

CERN Document Server

Hori, M; Eades, John; Gomikawa, K; Hayano, R S; Ono, N; Pirkl, Werner; Widmann, E; Torii, H A; Juhász, B; Barna, D; Horváth, D

2006-01-01

A femtosecond optical frequency comb and continuous-wave pulse- amplified laser were used to measure 12 transition frequencies of antiprotonic helium to fractional precisions of (9-16) 10/sup -9lifetimes hitherto unaccessible to our precision laser spectroscopy method. Comparisons with three-body QED calculations yielded an antiproton-to-electron mass ratio of M/sub pmacron//m/sub e/=1836.152 674(5).

The Titan haze revisted: Magnetospheric energy sorces quantitative tholin yields

Science.gov (United States)

Thompson, W. Reid; Mcdonald, Gene D.; Sagan, Carl

1994-01-01

We present laboratory measurements of the radiation yields of complex organic solids produced from N2/CH4 gas mixtures containing 10 or 0.1% CH4. These tholins are thought to resemble organic aerosols produced in the atmospheres of Titan, Pluto, and Triton. The tholin yields are large compared to the total yield of gaseous products: nominally, 13 (C + N)/100 eV for Titan tholin and 2.1 (C + N)/100 eV for Triton tholin. High-energy magnetospheric electrons responsible for tholin production represents a class distinct from the plasma electrons considered in models of Titan's aiglow. Electrons with E greater than 20 keV provide an energy flux approximately 1 x 10(exp -2) erg/cm/sec, implying from our measured tholin yields a mass flux of 0.5 to 4.0 x 10(exp -14) g/sq cm/sec of tholin. (The corresponding thickness of the tholin sedimentary column accumulated over 4 Gyr on Titan's surface is 4 to 30 m). This figure is in agreement with required mass fluxes computed from recent radiative transfer and sedimentation models. If, however, theses results, derived from experiments at approximately 2 mb, are applied to lower pressure levels toward peak auroral electron energy deposition and scaled with pressure as the gas-phase organic yields, the derived tholin mass flux is at least an order of magnitude less. We attrribute this difference to the fact that tholin synthesis occurs well below the level of maximum electron energy depositon and to possible contributions to tholis from UV-derived C2-hydrocarbons. We conclude that Tita tholin, produced by magnetospheric electrons, is alone sufficient to supply at least a significant fraction of Titan's haze-a result consistent with the fact that the optical properties of Titan tholin, among all proposed material, are best at reproducing Titan's geometric albedo spectrum from near UV to mid-IR in light-scattering models.

Electron transfer from electronic excited states to sub-vacuum electron traps in amorphous ice

International Nuclear Information System (INIS)

Vichnevetski, E.; Bass, A.D.; Sanche, L.

2000-01-01

We investigate the electron stimulated yield of electronically excited argon atoms (Ar * ) from monolayer quantities of Ar deposited onto thin films of amorphous ice. Two peaks of narrow width ( - electron-exciton complex into exciton states, by the transfer of an electron into a sub-vacuum electron state within the ice film. However, the 10.7 eV feature is shifted to lower energy since electron attachment to Ar occurs within small pores of amorphous ice. In this case, the excess electron is transferred into an electron trap below the conduction band of the ice layer

Practical electron dosimetry: a comparison of different types of ionization chambers

International Nuclear Information System (INIS)

Dohm, O.S.; Christ, G.

2002-01-01

Since Markus chambers are no longer recommended in the 1997 DIN 6800-2 version there are uncertainties as to the use of alternative chamber types for electron dosimetry. Therefore, we performed a comparison between different types of ionization chambers. In particular, the widespread Farmer and Roos chambers were compared with the Markus chamber for polarity effect, chamber-to-chamber variation, and deviations of the measured absorbed dose relative to the value obtained with the Roos chamber (which is regarded as an ideal Bragg-Gray-chamber). The perturbation correction factor at 60 Co radiation was determined experimentally as 1,029 ± 0,5% (Roos chamber) and 1,018 ± 0,5% (Markus chamber) for the investigated plane-parallel chambers. In addition, we could show that the Roos chambers do not have a larger chamber-to-chamber variation than the Farmer chambers. Likewise, our results suggest that Farmer chambers could be used for electron energies above 6 MeV. (orig.) [de

Theoretical lifetimes and fluorescence yields for multiply-ionized fluorine

International Nuclear Information System (INIS)

Tunnell, T.W.; Can, C.; Bhalla, C.P.

1978-01-01

Theoretical lifetimes and multiplet partial fluorescence yields for various fluorine ions with a single K-shell vacancy were calculated. For few-electron systems, the lifetimes and line fluorescence yields were computed in the intermediate coupling scheme with the inclusion of the effects arising from configuration interactions. 6 references

Control Mechanisms of the Electron Heat Flux in the Solar Wind: Observations in Comparison to Numerical Simulations

Science.gov (United States)

Stverak, S.; Hellinger, P.; Landi, S.; Travnicek, P. M.; Maksimovic, M.

2017-12-01

Recent understanding of the heat transport and dissipation in the expanding solar wind propose number of complex control mechanisms down to the electron kinetic scales. We investigate the evolution of electron heat flux properties and constraints along the expansion using in situ observations from Helios spacecraft in comparison to numerical kinetic simulations. In particular we focus on the roles of Coulomb collisions and wave-particle interactions in shaping the electron velocity distribution functions and thus controlling the heat transported by the electron heat flux. We show the general evolution of the electron heat flux to be driven namely by the Coulomb collisions. Locally we demonstrate the wave-particle interactions related to the kinetic plasma instabilities to be providing effective constraints in case of extreme heat flux levels.

Progress in Studies of Electron-Cloud-Induced Optics Distortions at CesrTA

International Nuclear Information System (INIS)

Crittenden, James; Penn, Gregory; Venturini, Marco; Harkay, Katherine; Holtzapple, Robert; Pivi, Mauro; Wang, Lanfa

2012-01-01

The Cornell Electron Storage Ring Test Accelerator (CesrTA) program has included extensive measurements of coherent betatron tune shifts for a variety of electron and positron beam energies, bunch population levels, and bunch train configurations. The tune shifts have been shown to result primarily from the interaction of the beam with the space-charge field of the beam-induced low-energy electron cloud in the vacuum chamber. Comparison to several advanced electron cloud simulation codes has allowed determination of the sensitivity of these measurements to physical parameters characterizing the synchrotron radiation flux, the production of photo-electrons on the vacuum chamber wall, the beam emittance, lattice optics, and the secondary-electron yield model. We report on progress in understanding the cloud buildup and decay mechanisms in magnetic fields and in field-free regions, addressing quantitatively the precise determination of the physical parameters of the modeling. Validation of these models will serve as essential input in the design of damping rings for future high-energy linear colliders.

The effect of electron beam parameters on the yield of gel fraction of some varnish systems

International Nuclear Information System (INIS)

Achmatowicz, T.; Jozwiak, H.; Zielinska, T.

1979-01-01

Results of studies carried out using a straight electron beam from accelerators LAE 13/9 and Elit-1 are presented. Using a variable dose rate, controlled by the distance from the accelerator window, pulse current, pulse duration and pulse repetition rate in LAE 13/9 the yield of the gel fraction of some varnishes and resins at a given dose has been determined. Using Elit-1 the dependence of the gel fraction content on the dose for pulses of various repetition rate has been examined. It has been shown that the dose rate and other beam parameters affect the course of the curing process of the examined compositions. The curing conditions established in LAE 13/9 can be a basis for processes carried out on a commercial scale. (author)

Electron beam effects in auger electron spectroscopy and scanning electron microscopy

International Nuclear Information System (INIS)

Fontaine, J.M.; Duraud, J.P.; Le Gressus, C.

1979-01-01

Electron beam effects on Si(100) and 5% Fe/Cr alloy samples have been studied by measurements of the secondary electron yield delta, determination of the surface composition by Auger electron spectroscopy and imaging with scanning electron microscopy. Variations of delta as a function of the accelerating voltage Esub(p) (0.5 -9 Torr has no effect on technological samples covered with their reaction layers; the sensitivities to the beam depend rather on the earlier mechanical, thermal and chemical treatment of the surfaces. (author)

Progress in studies of Electron-Cloud-Induced Optics Distortions at CESRTA

International Nuclear Information System (INIS)

Crittenden, J.A.; Calvey, J.R.; Dugan, G.F.; Kreinick, D.L.; Leong, Z.; Livezey, J.A.; Palmer, M.A.; Rubin, D.L.; Sagan, D.C.; Holtzapple, R.L.; Furman, M.A.; Penn, G.; Venturini, M.; Pivi, M.; Wang, L.; Harkay, K.

2010-01-01

The Cornell Electron Storage Ring Test Accelerator (CesrTA) program has included extensive measurements of coherent betatron tune shifts for a variety of electron and positron beam energies, bunch population levels, and bunch train configurations. The tune shifts have been shown to result primarily from the interaction of the beam with the space-charge field of the beam-induced low energy electron cloud in the vacuum chamber. Comparison to several advanced electron cloud simulation program packages has allowed determination of the sensitivity of these measurements to physical parameters characterizing the synchrotron radiation flux, the production of photoelectrons on the vacuum chamberwall, the beam emittance, lattice optics, and the secondary-electron yield model. We report on progress in understanding the cloud buildup and decay mechanisms in magnetic fields and in field-free regions, addressing quantitatively the precise determination of the physical parameters of the modeling. Validation of these models will serve as essential input in the design of damping rings for future high-energy linear colliders.

Determining the sputter yields of molybdenum in low-index crystal planes via electron backscattered diffraction, focused ion beam and atomic force microscope

Energy Technology Data Exchange (ETDEWEB)

Huang, H.S., E-mail: 160184@mail.csc.com.tw [New Materials Research and Development Department, China Steel Corporation, 1 Chung Kang Road, Hsiao Kang, Kaohsiung 812, Taiwan, ROC (China); Chiu, C.H.; Hong, I.T.; Tung, H.C. [New Materials Research and Development Department, China Steel Corporation, 1 Chung Kang Road, Hsiao Kang, Kaohsiung 812, Taiwan, ROC (China); Chien, F.S.-S. [Department of Physics, Tunghai University, 1727, Sec. 4, Xitun Dist., Taiwan Boulevard, Taichung 407, Taiwan, ROC (China)

2013-09-15

Previous literature has used several monocrystalline sputtering targets with various crystalline planes, respectively, to investigate the variations of the sputter yield of materials in different crystalline orientations. This study presents a method to measure the sputtered yields of Mo for the three low-index planes (100), (110), and (111), through using an easily made polycrystalline target. The procedure was firstly to use electron backscattered diffraction to identify the grain positions of the three crystalline planes, and then use a focused ion beam to perform the micro-milling of each identified grain, and finally the sputter yields were calculated from the removed volumes, which were measured by atomic force microscope. Experimental results showed that the sputter yield of the primary orientations for Mo varied as Y{sub (110)} > Y{sub (100)} > Y{sub (111)}, coincidental with the ranking of their planar atomic packing densities. The concept of transparency of ion in the crystalline substance was applied to elucidate these results. In addition, the result of (110) orientation exhibiting higher sputter yield is helpful for us to develop a Mo target with a higher deposition rate for use in industry. By changing the deformation process from straight rolling to cross rolling, the (110) texture intensity of the Mo target was significantly improved, and thus enhanced the deposition rate. - Highlights: • We used EBSD, FIB and AFM to measure the sputter yields of Mo in low-index planes. • The sputter yield of the primary orientations for Mo varied as Y{sub (110)} > Y{sub (100)} > Y{sub (111)}. • The transparency of ion was used to elucidate the differences in the sputter yield. • We improved the sputter rate of polycrystalline Mo target by adjusting its texture.

Calculated yields of ammonia in the radiolysis of deoxygenated solutions of glycylglycine

International Nuclear Information System (INIS)

Bolch, W.E.; Turner, J.E.; Yoshida, H.; Jacobson, K.B.

1988-01-01

This paper presents detailed Monte Carlo simulations of physical and chemical interactions occurring within electron tracks in deoxygenated solutions of glycylglycine. Hydrated electrons produced within these tracks react with the solute to produce ammonia and a peptide secondary free radical. Calculated yields of ammonia are presented for a range of solute concentrations and electron energies. Excellent agreement is found between calculated and measured yields of ammonia in solutions irradiated by 250-kVp x-rays and 60 Co gamma rays. 12 refs., 5 figs

Positron Spur Reactions with Excess Electrons and Anions in Liquid Organic Mixtures of Electron Acceptors

DEFF Research Database (Denmark)

Lévay, B.; Mogensen, O. E.

1980-01-01

By means of the positron lifetime technique we have measured positronium (Ps) yields in mixtures of nonpolar liquids with various electron scavengers which bind the electron fairly weakly (1–2 eV) in stable anions. The results are discussed with reference to recent excess electron works, and new...... experiments on anions and excess electrons are proposed. The minimum of the Ps yield versus CS2 concentration curves caused by partly delocalization of electrons on several scavenger molecules, which was observed previously in saturated aliphatic hydrocarbons occurred also in the saturated cyclic hydrocarbon...... cyclohexane, but did not appear in the aromatic benzene. This might be explained by the weak electron acceptor property of aromatics. In the Ps yield versus SF6 concentration curve in hexane a similar minimum appeared as in the CS2 case, probably by the same reason. By adding 0.8 M CS2 to the system...

Electron transfer from nucleobase electron adducts to 5-bromouracil. Is guanine an ultimate sink for the electron in irradiated DNA?

International Nuclear Information System (INIS)

Nese, C.; Yuan, Z.; Schuchmann, M.N.; Sonntag, C. von

1992-01-01

Electron transfer to 5-bromouracil (5-BrU) from nucleobase (N) electron adducts (and their protonated forms) has been studied by product analysis and pulse radiolysis. When an electron is transferred to 5-BrU, the ensuing 5-BrU radical anion rapidly loses a bromide ion; the uracilyl radical thus formed reacts with added t-butanol, yielding uracil. From the uracil yields measured as the function of [N]/[5-BrU] after γ-radiolysis of Ar-saturated solutions it is concluded that thymine and adenine electron adducts and their heteroatom-protonated forms transfer electrons quantitatively to 5-BrU. The data raise the question whether in DNA the guanine moiety may act as the ultimate sink of the electron in competition with other processes such as protonation at C(6) of the thymine electron adduct. (Author)

Production of hydrogen and deuterium negative ions in an electron cyclotron resonance driven plasma

Energy Technology Data Exchange (ETDEWEB)

Dougar-Jabon, V.D. [Industrial Univ. of Santander, Bucaramanga (Colombia)

2001-04-01

An electron cyclotron resonance source with driven plasma rings for hydrogen isotope ion production is studied. Extracted currents of positive and negative ions depending on gas pressure, microwave power value and extraction voltage are obtained. The study shows that the negative ion yield is an order of magnitude higher than the yield of positive particles when a driven ring is in contact with the surface of the plasma electrode. The production of negative ions of deuterium, D{sup -}, is close to the production of negative ions of light hydrogen isotope, H{sup -}. The comparison of the experimental data with the calculated ones shows that the most probable process of the H{sup -} and D{sup -} ion formation in the electron cyclotron driven plasma is dissociative attachment of electrons to molecules in high Rydberg states. For hydrogen ions and ions of deuterium, the negative current at a microwave power of 200 W through a 3-mm aperture and 8 kV extraction voltage are 4.7 mA and 3.1 mA respectively. (orig.)

Production of hydrogen and deuterium negative ions in an electron cyclotron resonance driven plasma

International Nuclear Information System (INIS)

Dougar-Jabon, V.D.

2001-01-01

An electron cyclotron resonance source with driven plasma rings for hydrogen isotope ion production is studied. Extracted currents of positive and negative ions depending on gas pressure, microwave power value and extraction voltage are obtained. The study shows that the negative ion yield is an order of magnitude higher than the yield of positive particles when a driven ring is in contact with the surface of the plasma electrode. The production of negative ions of deuterium, D - , is close to the production of negative ions of light hydrogen isotope, H - . The comparison of the experimental data with the calculated ones shows that the most probable process of the H - and D - ion formation in the electron cyclotron driven plasma is dissociative attachment of electrons to molecules in high Rydberg states. For hydrogen ions and ions of deuterium, the negative current at a microwave power of 200 W through a 3-mm aperture and 8 kV extraction voltage are 4.7 mA and 3.1 mA respectively. (orig.)

Yield and Yield Components of Vetch (Vigna radiata as Affected by the Use of Vermicompost and Phosphate Bio-fertilizer

Directory of Open Access Journals (Sweden)

Mohammad Mehdi Rahimi

2016-06-01

Full Text Available To evaluate the effects different levels of phosphate biofertilizer barvar-2 and vermi compost on yield and yield components of vetch plant (Vigna radiata L.in Yasouj a factorial experiments was performed in completely randomized design in crop year of 2013. Experimental treatments were phosphate biofertilizer barvar-2 at 3 levels (0, 50, 100 gram per hectare and vermicompost at 4 levels (0, 10, 20, 30 ton per hectare. In this study stem height, root length, biological yield, seed yield and harvest index was measured. ANOVA and comparison of means showed that vermicompost significantly increased stem height, economic and biological yields. Results, also, indicated that highest yield and biomass, 4.3 and 18.8 g/plant, observed respectively when 100 g/ha of barvar-2 and 30 t/ha of vermi compost were used. Using both of phosphate biofertilizer barvar-2 and vermicompost was better than their individnal usage. This indicates that combined use of these 2 factors would produce higher yield. It can be concluded that application of 100 g/ha of barvar-2 and 30 t/ha of vermicompost would a proper recommendation.

Secondary electron emission from textured surfaces

Science.gov (United States)

Huerta, C. E.; Patino, M. I.; Wirz, R. E.

2018-04-01

In this work, a Monte Carlo model is used to investigate electron induced secondary electron emission for varying effects of complex surfaces by using simple geometric constructs. Geometries used in the model include: vertical fibers for velvet-like surfaces, tapered pillars for carpet-like surfaces, and a cage-like configuration of interlaced horizontal and vertical fibers for nano-structured fuzz. The model accurately captures the secondary electron emission yield dependence on incidence angle. The model shows that unlike other structured surfaces previously studied, tungsten fuzz exhibits secondary electron emission yield that is independent of primary electron incidence angle, due to the prevalence of horizontally-oriented fibers in the fuzz geometry. This is confirmed with new data presented herein of the secondary electron emission yield of tungsten fuzz at incidence angles from 0-60°.

The secondary electron yield of air exposed metal surfaces at the example of niobium

CERN Document Server

Scheuerlein, C; Taborelli, M

2002-01-01

The secondary electron yield (SEY) variation of atomically clean metal surfaces due to air exposures and during subsequent heat treatments is described with the example of a sputter-deposited Nb thin film. Corresponding variations of the surface chemical composition have been monitored using AES and SSIMS. On the basis of these results and of previously obtained SEY results on metals and metal oxides the origin of the SEY variations is discussed. The SEY increase, which is generally observed during long lasting air exposures of clean metals, is mainly caused by the adsorption of an airborne carbonaceous contamination layer. The estimated value of about 3 for the maximum SEY of this layer is higher than that of all pure metals. Only in some cases the air-formed oxide can contribute to the air exposure induced SEY increase while many oxides have a lower SEY than their parent metals. From the experimental data it can also be excluded that the SEY increase during air exposures is mainly due to an increased second...

Electronic energy loss of fast molecules in matter

International Nuclear Information System (INIS)

Steinbeck, J.

1975-06-01

In high velocity collisions of molecular ions the correlated motion influence of the ion cores on the electronic energy loss is investigated. The stopping power in first Born approximation for a random arrangement of target atoms can be formulated in terms of the inelastic electronic structure factor. In treating the target atoms in Hartree-Fock approximation each electron can be regarded as stopping the ion independent of all other electrons without restriction by the Pauli principle. A second equivalent formulation of the stopping power leads to the dielectric function of the target. The results are applied to the stopping of H 2 + -ions. For vanishing distance between the two protons the stopping power per particle is twice that for single proton collisions. For distances in the order of the Bohr radius the correlated stopping power may even be smaller than for uncorrelated protons. With increasing distances the correlation influence vanishes. The stopping of H 2 + -ions in C, Si and Ge is discussed using Clementi wave functions for the core electrons and a free electron approximation with Lindhard's dielectric function for the valence electrons. The comparison with the only experimental result available for H 2 + in C at 300 keV yields qualitative agreement. (orig.) [de

Yield of single-strand breaks in the DNA of E. coli 10 msec after irradiation

Energy Technology Data Exchange (ETDEWEB)

Fox, R A; Fielden, E M; Sapora, O [Institute of Cancer Research, Sutton (UK). Surrey Branch

1976-04-01

The rapid mixing of 0.3M alkali with a suspension of E.coli B/r 6 +- 3 and 144 +- 3 msec after irradiation with electrons (4.3 MeV, 0 to 50 krad) has been used to make a comparison of the yields of single strand breaks in the presence and absence of oxygen. No significant difference was observed between the numbers of single strand breaks appearing at 6 and 144 msec after irradiation. Assuming that mixing with alkali inactivates the cellular repair enzymes within several milliseconds, these results indicate that enzymic repair does not operate within this time scale. It seems probable that radiation chemical processes are responsible for the initial oxygen effect on single strand breaks.

Analysis of abused drugs by selected ion monitoring: quantitative comparison of electron impact and chemical ionization

International Nuclear Information System (INIS)

Foltz, R.L.; Knowlton, D.A.; Lin, D.C.K.; Fentiman, A.F. Jr.

1975-01-01

A comparison was made of the relative sensitivities of electron impact and chemical ionization when used for selected ion monitoring analysis of commonly abused drugs. For most of the drugs examined chemical ionization using ammonia as the reactant gas gave the largest single m/e ion current response per unit weight of sample. However, if maximum sensitivity is desired it is important to evaluate electron impact and chemical ionization with respect to both maximum response and degree of interference from background and endogenous materials

Comparison of quantification methods for the analysis of polychlorinated alkanes using electron capture negative ionization mass spectrometry.

NARCIS (Netherlands)

Rusina, T.; Korytar, P.; de Boer, J.

2011-01-01

Four quantification methods for short-chain chlorinated paraffins (SCCPs) or polychlorinated alkanes (PCAs) using gas chromatography electron capture negative ionisation low resolution mass spectrometry (GC-ECNI-LRMS) were investigated. The method based on visual comparison of congener group

Comparison of quantification methods for the analysis of polychlorinated alkanes using electron capture negative ionisation mass spectrometry

NARCIS (Netherlands)

Rusina, T.; Korytar, P.; Boer, de J.

2011-01-01

Four quantification methods for short-chain chlorinated paraffins (SCCPs) or polychlorinated alkanes (PCAs) using gas chromatography electron capture negative ionisation low resolution mass spectrometry (GC-ECNI-LRMS) were investigated. The method based on visual comparison of congener group

The heritability of milk yield and fat percentage in the Friesian cattle in the province of Friesland

NARCIS (Netherlands)

El-Shimy, S.A.F.

1956-01-01

The heritability of milk yield and fat percentage was calculated of herd-registered cattle in Friesland. The estimates were based on daughter-dam comparisons. Comparisons covered the first three lactations. The average heritability estimates of milk yield within sires, and according to the different

Satellite observations of energetic electron precipitation during the 1979 solar eclipse and comparisons with rocket measurements

Science.gov (United States)

Gaines, E. E.; Imhof, W. L.; Voss, H. D.; Reagan, J. B.

1983-07-01

During the solar eclipse of 26 February 1979, the P78-1 satellite passed near Red Lake, Ontario, at an altitude of about 600 km. On two consecutive orbits spanning the time of total eclipse, energetic electrons were measured with two silicon solid state detector spectrometers having excellent energy and angular resolution. Significant fluxes of precipitating electrons were observed near the path of totality. Comparisons of flux intensities and energy spectra with those measured from a Nike Orion and two Nike Tomahawk rockets launched near Red Lake before and during total eclipse give good agreement and indicate that the electron precipitation was relatively uniform for more than an hour and over a broad geographical area.

Satellite observations of energetic electron precipitation during the 1979 solar eclipse and comparisons with rocket measurements

International Nuclear Information System (INIS)

Gaines, E.E.; Imhof, W.L.; Voss, H.D.; Reagan, J.B.

1983-01-01

During the solar eclipse of 26 February 1979, the P78-1 satellite passed near Red Lake, Ontario, at an altitude of approx. 600 km. On two consecutive orbits spanning the time of total eclipse, energetic electrons were measured with two silicon solid state detector spectrometers having excellent energy and angular resolution. Significant fluxes of precipitating electrons were observed near the path of totality. Comparisons of flux intensities and energy spectra with those measured from a Nike Orion and two Nike Tomahawk rockets launched near Red Lake before and during total eclipse give good agreement and indicate that the electron precipitation was relatively uniform for more than an hour and over a broad geographical area. (author)

The CMS electromagnetic calorimeter and the search for the Higgs boson in the decay channel H {yields} WW{sup *} {yields} 2e2{nu}; Le calorimetre electromagnetique de CMS et la recherche du boson de Higgs dans le canal de desintegration H {yields} WW{sup *} {yields} 2e2{nu}

Energy Technology Data Exchange (ETDEWEB)

Rovelli, I.Ch

2006-01-15

CMS is one of the four experiments that will take data at the LHC. Large part of my work was devoted to the development of electron reconstruction tools aimed at improving the Higgs boson discovery potential in the H {yields} WW{sup *} {yields} 2e2{nu} channel. A major role in the electron reconstruction is played by the electromagnetic calorimeter ECAL, an homogeneous calorimeter made of scintillating PbWO{sub 4} crystals. The first 3 chapters give an overview of LHC and CMS.In chapter 4 the analysis of the data collected during the 2003 electromagnetic calorimeter test beam is presented. First the problem of the intercalibration at the test beam is addressed. This is a major task, since the precision of the intercalibration directly affects the constant term of the energy resolution, for which the CMS goal is to reach a precision better than 0.5%. The good initial intercalibration, anyway, could be spoiled during the data taking by the effects of the radiation on the crystals, which can change the relative responses of the channels. A monitoring laser system is foreseen at CMS. The possibility to check the calibration stability and to correct the changes in the response with a precision within the required limits is demonstrated. Chapter five describes the electron reconstruction and identification in CMS. A crucial problem for the electron reconstruction is represented by the Bremsstrahlung emission in the tracker. A tracking procedure dealing with the Bremsstrahlung energy loss is discussed. Together with an improvement in the reconstruction efficiency, the procedure allows to identify electrons with a small fraction of radiated energy, which can be usefully exploited for the ECAL calibration. The developed algorithms are applied in chapter 6, which presents the study of the CMS discovery potential of the Higgs boson in the H {yields} WW{sup *} {yields} 2e2{nu} channel. This is the discovery channel in the range of masses between 2m{sub W} and 2m{sub Z}. Here

Theory of the ionization yield in gases under electron irradiation

International Nuclear Information System (INIS)

Inokuti, M.

1974-01-01

The total number N/sub i/(T) of ionizations that an incident electron of kinetic energy T causes in a pure gas obeys an integral equation known as the Fowler equation. Its solution is shown to closely approximate N/sub i/(T) = (T -- U)/W/sub a/ for T exceeding several multiples of the first ionization energy I, where U and W/sub a/ are constants having the energy dimension. Simple formulas express U and W/sub a/ in terms of various cross sections for electron inelastic collisions with a gas molecule. In particular, U - I represents the average kinetic energy of a subionization electron. (35 refs) (U.S.)

Comparison of the accuracies of multi-frequency electronic apex locators in teeth with enlarged apical foramina: ex vivo

Directory of Open Access Journals (Sweden)

Mügem Aslı Ekici

2018-01-01

Full Text Available Objective: The aim of this study was to compare the accuracy of a newly developed multi-frequency electronic apex locator iPex II with three different multi-frequency electronic apex locators in teeth with different sizes of apical foramina. Materials and Method: Twenty-six extracted mandibular premolars were used in this study. The teeth were decoronated, and the root canals were coronally flared. Actual working length was determined by inserting a #15 K-file until the tip was visualized just within apical foramen. Actual working length was established 0.5 mm short of the distance between the rubber stopper and the file tip. Using Protaper F1, F2 and F3 files (Dentsply Maillefer, over-instrumentation 1 mm beyond the apical foramen was done. The teeth were embedded in teflon molds with alginate exposing the coronal 5 mm. Electronic working length measurements were done by using Raypex 5 (VDW, Raypex 6 (VDW, iPex (NSK Inc. and iPex II (NSK Inc. electronic apex locators. Differences between the electronic and actual working lengths were calculated. One-way analysis of variance (ANOVA was used for the statistical analysis of the accuracies of the electronic apex locators (α=0.05. Results: Inter-group comparisons revealed that there was no statistically significant difference between the accuracies of the different electronic apex locators (p>0.05. Intra-group comparisons also revealed that there was no statistically significant difference between different apical foramen sizes (p>0.05. Conclusion: iPex II and the other electronic apex locators provided similar endodontic working length measurements in teeth with enlarged apical foramina. All electronic apex locators tested in this study were found clinically acceptable for working length determination.

Strong morphological and crystallographic texture and resulting yield strength anisotropy in selective laser melted tantalum

International Nuclear Information System (INIS)

Thijs, Lore; Montero Sistiaga, Maria Luz; Wauthle, Ruben; Xie, Qingge; Kruth, Jean-Pierre; Van Humbeeck, Jan

2013-01-01

Selective laser melting (SLM) makes use of a high energy density laser beam to melt successive layers of metallic powders in order to create functional parts. The energy density of the laser is high enough to melt refractory metals like Ta and produce mechanically sound parts. Furthermore, the localized heat input causes a strong directional cooling and solidification. Epitaxial growth due to partial remelting of the previous layer, competitive growth mechanism and a specific global direction of heat flow during SLM of Ta result in the formation of long columnar grains with a 〈1 1 1〉 preferential crystal orientation along the building direction. The microstructure was visualized using both optical and scanning electron microscopy equipped with electron backscattered diffraction and the global crystallographic texture was measured using X-ray diffraction. The thermal profile around the melt pool was modeled using a pragmatic model for SLM. Furthermore, rotation of the scanning direction between different layers was seen to promote the competitive growth. As a result, the texture strength increased to as large as 4.7 for rotating the scanning direction 90° every layer. By comparison of the yield strength measured by compression tests in different orientations and the averaged Taylor factor calculated using the viscoplastic self-consistent model, it was found that both the morphological and crystallographic texture observed in SLM Ta contribute to yield strength anisotropy

Study of nonproportionality in the light yield of inorganic scintillators

Energy Technology Data Exchange (ETDEWEB)

Singh, Jai [School of Engineering and IT, B-purple-12, Faculty of EHSE, Charles Darwin University, Darwin, Northern Territory 0909 (Australia)

2011-07-15

Using a phenomenological approach, the light yield is derived for inorganic scintillators as a function of the rates of linear, bimolecular, and Auger processes occurring in the electron track initiated by an x ray or a {gamma}-ray photon. A relation between the track length and incident energy is also derived. It is found that the nonproportionality in the light yield can be eliminated if either nonlinear processes of interaction among the excited electrons, holes, and excitons can be eliminated from occurring or the high density situation can be relieved by diffusion of carriers from the track at a faster rate than the rate of activation of nonlinear processes. The influence of the track length and radius on the yield nonproportionality is discussed in view of the known experimental results. Inventing new inorganic scintillating materials with high carrier mobility can lead to a class of proportional inorganic scintillators. Results agree qualitatively with experimental results for the dependence of light yield on the incident energy.

Study of nonproportionality in the light yield of inorganic scintillators

International Nuclear Information System (INIS)

Singh, Jai

2011-01-01

Using a phenomenological approach, the light yield is derived for inorganic scintillators as a function of the rates of linear, bimolecular, and Auger processes occurring in the electron track initiated by an x ray or a γ-ray photon. A relation between the track length and incident energy is also derived. It is found that the nonproportionality in the light yield can be eliminated if either nonlinear processes of interaction among the excited electrons, holes, and excitons can be eliminated from occurring or the high density situation can be relieved by diffusion of carriers from the track at a faster rate than the rate of activation of nonlinear processes. The influence of the track length and radius on the yield nonproportionality is discussed in view of the known experimental results. Inventing new inorganic scintillating materials with high carrier mobility can lead to a class of proportional inorganic scintillators. Results agree qualitatively with experimental results for the dependence of light yield on the incident energy.

Dimension yields from short logs of low-quality hardwood trees.

Science.gov (United States)

Howard N. Rosen; Harold A. Stewart; David J. Polak

1980-01-01

Charts are presented for determining yields of 4/4 dimension cuttings from short hardwood logs of aspen, soft maple, black cherry, yellow-poplar, and black walnut for several cutting grades and bolt sizes. Cost comparisons of short log and standard grade mixes show sizes. Cost comparisons of short log and standard grade mixes show the estimated least expensive...

Comparison of biomolecule desorption yields for low and high energy primary ions

International Nuclear Information System (INIS)

Kamensky, I.; Hakansson, P.; Sundqvist, B.; McNeal, C.J.; MacFarlane, R.

1982-01-01

Ion induced desorption yields of molecular ions from samples of cesium iodide, glycylglycine, ergosterol, bleomycin and a trinucleoside diphosphate have been studied using primary beams of 54 MeV 63 Cu 9+ and 3 keV 133 Cs + . Mass analysis was performed with a time-of-flight technique. Each sample was studied with the same spectrometer for both low and high energy primary ions and without opening of the vacuum chamber in between the measurements. The results show that fast heavy ions give larger yields for all samples studied and that the yield ratios for high to low energy desorption increase with the mass of the sample molecule. (orig.)

Cardiac auscultation training of medical students: a comparison of electronic sensor-based and acoustic stethoscopes

Science.gov (United States)

Høyte, Henning; Jensen, Torstein; Gjesdal, Knut

2005-01-01

Background To determine whether the use of an electronic, sensor based stethoscope affects the cardiac auscultation skills of undergraduate medical students. Methods Forty eight third year medical students were randomized to use either an electronic stethoscope, or a conventional acoustic stethoscope during clinical auscultation training. After a training period of four months, cardiac auscultation skills were evaluated using four patients with different cardiac murmurs. Two experienced cardiologists determined correct answers. The students completed a questionnaire for each patient. The thirteen questions were weighted according to their relative importance, and a correct answer was credited from one to six points. Results No difference in mean score was found between the two groups (p = 0.65). Grading and characterisation of murmurs and, if present, report of non existing murmurs were also rated. None of these yielded any significant differences between the groups. Conclusion Whether an electronic or a conventional stethoscope was used during training and testing did not affect the students' performance on a cardiac auscultation test. PMID:15882458

Comparison of some yield and quality criteria in organically and ...

African Journals Online (AJOL)

STORAGESEVER

2008-05-02

May 2, 2008 ... The simplest definition organic farming is a production system, which excludes ... Key words: Organic growing, conventional growing, lettuce, yield, quality. ... capitata cv Gloria, an iceberg type) were sown in seed trays.

Temperature impact on the primary radiolysis yields concerning the hydrous electron

International Nuclear Information System (INIS)

Baldacchino, G.; Vigneron, G.; Pommeret, St.

2005-01-01

We have studied the impact of temperature on the water radiolysis formation rate of the hydrous electron in presence of selenate di-anion SeO 4 2+ . We have used a high temperature (up to 500 Celsius degrees) optical cell coupled to the electron accelerator Alienor. It appears that the capture of the hydrous electron by selenate follows an Arrhenius law till the sub-critical range, beyond this range the kinetics of the reaction seems more erratic. We have also studied the capture of the hydrous electron by methyl-viologen (MV 2+ ) at 20 and 380 Celsius degrees. It seems that at high temperature more hydrous electrons are produced, it might be interpreted as a consequence of the shift toward the right of the following equilibrium reaction: OH - + H . ↔ e - (aq) + H 2 O. All these results need to be confirmed. (A.C.)

Calculational estimations of neutron yield from ADS target

International Nuclear Information System (INIS)

Degtyarev, I.I.; Liashenko, O.A.; Yazynin, I.A.; Belyakov-Bodin, V.I.; Blokhin, A.I.

2002-01-01

Results of computational studies of high power spallation thick ADS (Accelerator-Driven System) targets with 0.8-1.2 GeV proton beams are given. Comparisons of experiments and calculations of double differential and integral n/p yield are also described. (author)

Radioisotope production with electron accelerators

International Nuclear Information System (INIS)

Brinkman, G.A.

1978-01-01

The production of radio isotopes with electron accelerators proceeds mainly by secondary photons (bremsstrahlung), produced in an interaction between the electrons and the Coulomb field of the nuclei of a converter. The production yields depend on: the initial electron energy, the Z and thickness of the bremsstrahlung-converter, the Z, A and the thickness of the target, the geometric set up and the cross section for a particular reaction. In this article the production is only considered for thin bremsstrahlung converters in combination with an electron 'sweep' magnet. Simple formulae are given for the calculations of production yields under standard conditions with only sigmasub(q) (the cross section per equivalent quantum) and f (the fraction of the photons that hit the target) as variables and for the calculations of the dose rate at the production point. The units in which the yields are expressed in the literature (units of sigmasub(q) dose, electron beam intensity, monitor response) are discussed. (Auth.)

Effect of planting date on yield of wheat genotypes in Sindh

International Nuclear Information System (INIS)

Khokhar, Z.; Hussain, I.

2010-01-01

Due to reduction in tillering period and increased risk of hot weather during grain filling, late planting results in linear reduction in wheat grain yield. A study was undertaken to determine the effects of planting dates on growth and yield of different wheat genotypes in Sindh. The trial was laid out in RCBD with split plot arrangement having four replications during 2000-01 and 2001-02 at Sakrand, Sindh. Four sowing dates i.e. November 1 and 15, December 1 and 15 were in main plots, whereas six wheat genotypes (V-7001, V-7002, V-7004, MPT-6, Abadgar-93, and Anmol-91) were in sub plots. Because of better tillering, plant growth, growth period, number of grain per unit area and grain weight, November 15 planted wheat had maximum grain yield of 5904 kg ha/sup -1/, followed by November 1 and December 1 which gave 5302 and 4948 kg ha/sup -1 /respectively. Wheat planted on December 15 resulted in minimum grain yield of 4756 kg ha/sup -1/. Wheat genotype, V-7002 had significantly (P<0.05) higher grain yield of 5578 kg ha/sup -1/ in comparison with other genotypes. Whereas genotype MPT-6 had grain yield of 5366 kg ha-1 that was also significantly higher than other genotypes. However, V-7004 had minimum grain yield of 4716 kg ha/sup -1/ in comparison with other genotypes. While evaluating performance of different genotypes on different sowing dates, V-7002 resulted in maximum yield on November 15 and late planting. On the other hand, V-7004 had lower yield on all planting dates. Results from the study revealed that maximum grain yield could be achieved with wheat planted in first fortnight of November and any delay in wheat planting might reduce wheat yield. (author)

Design of an electronic charged particle spectrometer to measure (ρR), yield, and implosion symmetry on the OMEGA Upgrade

International Nuclear Information System (INIS)

Hicks, D.G.; Li, C.K.; Petrasso, R.D.; Wenzel, K.W.; Knauer, J.P.

1994-11-01

The preliminary design for a state-of-the-art diagnostic that will measure a broad energy spectrum of charged particles generated in the OMEGA Upgrade facility is investigated. Using a set of photodiodes (∼10) and a 0.8 Tesla permanent magnet, the diagnostic will uniquely determine particle energies and identities from 0.2 MeV up to the maximum charged particle energies (10.6 MeV tritons, 12.5 MeV deuterons and 17.4 MeV protons). With its high density picture elements, each photodiode has 10 6 single-hit detectors, giving the spectrometer a dynamic range of 1 - 10 5 particles/shot. For example, in the case of a DT yield of 10 9 neutrons, about 100 knock-on charged particles will be detected when the spectrometer aperture is 60 cm from the implosion. Furthermore, the measurement of knock-on D and T spectra will allow ρR's up to 0.15 g/cm 2 to be measured (for a 1 keV plasma), or 0.3 g/cm 2 2 if hydrogen doping is used. In addition, the yield and slowing down of secondary protons may be used to determine ρR up to 0.3 g/cm 2 . Significantly, this diagnostic will also directly measure the DD fusion yield and energy degradation of nascent 3 MeV protons. By using two such compact spectrometers to measure the yield and spectra on widely separated ports around the OMEGA Upgrade target chamber, the implosion and bum symmetry can be determined. Furthermore, the ion temperature, and, in principle, even the electron temperature can be measured. The diagnostic and its development will be fully tested at several critical steps, utilizing 0.2-16 MeV protons (and several other charged particles and neutrons) from our absolutely calibrated Cockcroft-Walton facility

Measure of the e+e-{yields}bb Cross Section at the LEP Energies; Medida de la seccion eficaz e''+e''-{yields}bb a las Energias de LEP

Energy Technology Data Exchange (ETDEWEB)

Arce Dubois, P

1992-07-01

In the present work I analyse the data collected during 1990 by the L3 detector, situated in the electron-positron collider LEP. After selecting the events e''+e''-{yields} bb through their semileptonic decays into muons, I calculate the cross section for the process e''+e''- {yields} bb at different energy points around the mass of the vectorial boson Z, and I measure some parameters of the Standard Model, namely, the Br(b{yields}{mu} ),{gamma}{sub z}n-{yields}bb/{gamma}{sub z}n{yields}had and {gamma}{sub z}n{yields}bb{gamma}{sub z}n{yields}e''+e''-. (Author) 26 refs.

Yield of single-strand breaks in the DNA of E.coli 10 msec after irradiation

International Nuclear Information System (INIS)

Fox, R.A.; Fielden, E.M.; Sapora, O.

1976-01-01

The rapid mixing of 0.3M alkali with a suspension of E.coli B/r 6 +- 3 and 144 +- 3 msec after irradiation with electrons (4.3 MeV, 0 to 50 krad) has been used to make a comparison of the yields of single strand breaks in the presence and absence of oxygen. No significant difference was observed between the numbers of single strand breaks appearing at 6 and 144 msec after irradiation. Assuming that mixing with alkali inactivates the cellular repair enzymes within several milliseconds, these results indicate that enzymic repair does not operate within this time scale. It seems probable that radiation chemical processes are responsible for the initial oxygen effect on single strand breaks. (U.K.)

Comparison of multivariate preprocessing techniques as applied to electronic tongue based pattern classification for black tea

International Nuclear Information System (INIS)

Palit, Mousumi; Tudu, Bipan; Bhattacharyya, Nabarun; Dutta, Ankur; Dutta, Pallab Kumar; Jana, Arun; Bandyopadhyay, Rajib; Chatterjee, Anutosh

2010-01-01

In an electronic tongue, preprocessing on raw data precedes pattern analysis and choice of the appropriate preprocessing technique is crucial for the performance of the pattern classifier. While attempting to classify different grades of black tea using a voltammetric electronic tongue, different preprocessing techniques have been explored and a comparison of their performances is presented in this paper. The preprocessing techniques are compared first by a quantitative measurement of separability followed by principle component analysis; and then two different supervised pattern recognition models based on neural networks are used to evaluate the performance of the preprocessing techniques.

X-ray photoelectron spectroscopy and secondary electron yield analysis of Al and Cu samples exposed to an accelerator environment

Science.gov (United States)

Rosenberg, R. A.; McDowell, M. W.; Ma, Q.; Harkay, K. C.

2003-09-01

It is well known that exposure to an accelerator environment can cause ``conditioning'' of the vacuum chamber surfaces. In order to understand the manner in which the surface structure might influence the production of gases and electrons in the accelerator, such surfaces should be studied both before and after exposure to accelerator conditions. Numerous studies have been performed on representative materials prior to being inserted into an accelerator, but very little has been done on materials that have ``lived'' in the accelerator for extended periods. In the present work, we mounted Al and Cu coupons at different positions in a section of the Advanced Photon Source storage ring and removed them following exposures ranging from 6 to 18 months. X-ray photoelectron spectroscopy (XPS) of the surface was performed before and after exposure. Changes were observed that depended on the location and whether the coupon was facing the chamber interior or chamber wall. These results will be presented and compared to XPS and secondary electron yield data obtained from laboratory measurements meant to simulate the accelerator conditions.

Echo 7: Magnetospheric properties determined by artificial electron beams

International Nuclear Information System (INIS)

Nemzek, R.J.

1990-01-01

The sounding rocket Echo 7 was launched from the Poker Flat Research Range. An on-board accelerator injected high-power electron beams into the magnetospheric tail near L = 6.5. After mirroring at the southern conjugate point, about 20 percent of the initial beam electrons returned to the North as Conjugate Echoes, where detectors (scintillators and spectrometers) on four subpayloads measured their energy and bounce time. The other 80 percent of the beam was pitch angle diffused by wave near the equatorial plane either into the conjugate atmosphere or up to mirror points above the payload. Comparison of measured values to calculations showed that the actual magnetosphere during the flight was well-described by the Tsyganenko-Usmanov model magnetosphere with a Kp value of 2- or 2+. Analysis of echo energies yielded values for the highly variable magnetospheric convection electric field

Comparison of two screening corrections to the additivity rule for the calculation of electron scattering from polyatomic molecules

International Nuclear Information System (INIS)

Blanco, F.; Rosado, J.; Illana, A.; Garcia, G.

2010-01-01

The SCAR and EGAR procedures have been proposed in order to extend to lower energies the applicability of the additivity rule for calculation of electron-molecule total cross sections. Both those approximate treatments arise after considering geometrical screening corrections due to partial overlapping of atoms in the molecule, as seen by the incident electrons. The main features, results and limitations of both treatments are put here in comparison by means of their application to some different sized species.

Destabilization of the electron Bernstein modes by runaway electrons

International Nuclear Information System (INIS)

Hitchcock, D.A.; Mahajan, S.M.

1982-01-01

It is shown that the electromagnetic finite k/sub parallel/ electron Bernstein mode can be destabilized by the runaway electron distribution which results from the quasilinear action of the magnetized plasma oscillation. This mechanism is shown to yield growth rates of the order of 10 8 sec -1 and is suggested as a mechanism for the enchanced cyclotron harmonic emission in the presence of runaway electrons

Midwest agriculture and ENSO: A comparison of AVHRR NDVI3g data and crop yields in the United States Corn Belt from 1982 to 2014

Science.gov (United States)

Glennie, Erin; Anyamba, Assaf

2018-06-01

A time series of Advanced Very High Resolution Radiometer (AVHRR) derived normalized difference vegetation index (NDVI) data were compared to National Agricultural Statistics Service (NASS) corn yield data in the United States Corn Belt from 1982 to 2014. The main objectives of the comparison were to assess 1) the consistency of regional Corn Belt responses to El Niño/Southern Oscillation (ENSO) teleconnection signals, and 2) the reliability of using NDVI as an indicator of crop yield. Regional NDVI values were used to model a seasonal curve and to define the growing season - May to October. Seasonal conditions in each county were represented by NDVI and land surface temperature (LST) composites, and corn yield was represented by average annual bushels produced per acre. Correlation analysis between the NDVI, LST, corn yield, and equatorial Pacific sea surface temperature anomalies revealed patterns in land surface dynamics and corn yield, as well as typical impacts of ENSO episodes. It was observed from the study that growing seasons coincident with La Niña events were consistently warmer, but El Niño events did not consistently impact NDVI, temperature, or corn yield data. Moreover, the El Niño and La Niña composite images suggest that impacts vary spatially across the Corn Belt. While corn is the dominant crop in the region, some inconsistencies between corn yield and NDVI may be attributed to soy crops and other background interference. The overall correlation between the total growing season NDVI anomaly and detrended corn yield was 0.61(p = 0.00013), though the strength of the relationship varies across the Corn Belt.

Exoplanet Yield Estimation for Decadal Study Concepts using EXOSIMS

Science.gov (United States)

Morgan, Rhonda; Lowrance, Patrick; Savransky, Dmitry; Garrett, Daniel

2016-01-01

The anticipated upcoming large mission study concepts for the direct imaging of exo-earths present an exciting opportunity for exoplanet discovery and characterization. While these telescope concepts would also be capable of conducting a broad range of astrophysical investigations, the most difficult technology challenges are driven by the requirements for imaging exo-earths. The exoplanet science yield for these mission concepts will drive design trades and mission concept comparisons.To assist in these trade studies, the Exoplanet Exploration Program Office (ExEP) is developing a yield estimation tool that emphasizes transparency and consistent comparison of various design concepts. The tool will provide a parametric estimate of science yield of various mission concepts using contrast curves from physics-based model codes and Monte Carlo simulations of design reference missions using realistic constraints, such as solar avoidance angles, the observatory orbit, propulsion limitations of star shades, the accessibility of candidate targets, local and background zodiacal light levels, and background confusion by stars and galaxies. The python tool utilizes Dmitry Savransky's EXOSIMS (Exoplanet Open-Source Imaging Mission Simulator) design reference mission simulator that is being developed for the WFIRST Preliminary Science program. ExEP is extending and validating the tool for future mission concepts under consideration for the upcoming 2020 decadal review. We present a validation plan and preliminary yield results for a point design.

Comparison of winter wheat yield sensitivity to climate variables under irrigated and rain-fed conditions

Science.gov (United States)

Xiao, Dengpan; Shen, Yanjun; Zhang, He; Moiwo, Juana P.; Qi, Yongqing; Wang, Rende; Pei, Hongwei; Zhang, Yucui; Shen, Huitao

2016-09-01

Crop simulation models provide alternative, less time-consuming, and cost-effective means of determining the sensitivity of crop yield to climate change. In this study, two dynamic mechanistic models, CERES (Crop Environment Resource Synthesis) and APSIM (Agricultural Production Systems Simulator), were used to simulate the yield of wheat ( Triticum aestivum L.) under well irrigated (CFG) and rain-fed (YY) conditions in relation to different climate variables in the North China Plain (NCP). The study tested winter wheat yield sensitivity to different levels of temperature, radiation, precipitation, and atmospheric carbon dioxide (CO2) concentration under CFG and YY conditions at Luancheng Agro-ecosystem Experimental Stations in the NCP. The results from the CERES and APSIM wheat crop models were largely consistent and suggested that changes in climate variables influenced wheat grain yield in the NCP. There was also significant variation in the sensitivity of winter wheat yield to climate variables under different water (CFG and YY) conditions. While a temperature increase of 2°C was the threshold beyond which temperature negatively influenced wheat yield under CFG, a temperature rise exceeding 1°C decreased winter wheat grain yield under YY. A decrease in solar radiation decreased wheat grain yield under both CFG and YY conditions. Although the sensitivity of winter wheat yield to precipitation was small under the CFG, yield decreased significantly with decreasing precipitation under the rainfed YY treatment. The results also suggest that wheat yield under CFG linearly increased by ≈3.5% per 60 ppm (parts per million) increase in CO2 concentration from 380 to 560 ppm, and yield under YY increased linearly by ≈7.0% for the same increase in CO2 concentration.

The impact of long-range electron-hole interaction on the charge separation yield of molecular photocells

Science.gov (United States)

Nemati Aram, Tahereh; Ernzerhof, Matthias; Asgari, Asghar; Mayou, Didier

2017-01-01

We discuss the effects of charge carrier interaction and recombination on the operation of molecular photocells. Molecular photocells are devices where the energy conversion process takes place in a single molecular donor-acceptor complex attached to electrodes. Our investigation is based on the quantum scattering theory, in particular on the Lippmann-Schwinger equation; this minimizes the complexity of the problem while providing useful and non-trivial insight into the mechanism governing photocell operation. In this study, both exciton pair creation and dissociation are treated in the energy domain, and therefore there is access to detailed spectral information, which can be used as a framework to interpret the charge separation yield. We demonstrate that the charge carrier separation is a complex process that is affected by different parameters, such as the strength of the electron-hole interaction and the non-radiative recombination rate. Our analysis helps to optimize the charge separation process and the energy transfer in organic solar cells and in molecular photocells.

Comparison of Technical and Economical Effect of Different Planters using Varied Seed Rates on Canola Yield in Moghan Region

Directory of Open Access Journals (Sweden)

J Taghinazhad

2017-10-01

. Results and Discussion The evaluation of results of drill types showed that there was significant difference between the planters type and other performance parameters. Different planters with varied seed rates also had significant effects on germination at 1% probability level and B4 had maximum percentage of seed germination (89.45%. Uniformity of seed distribution was found to be the highest for B4 in vertical distribution uniformity (72.62% and inter-row uniformity (84.25%. The analysis of variance for two years showed that the grain yield and establishment of seed were significantly affected by year. Result of variance analysis for yield indicated that there was a significant difference between planting machines in 1% of probability level. Therefore, maximum yield in this experiment related to B4 with 2672 kg ha-1. The results of technical and economic comp ration indicate that the added net income of B4, was 4940 thousand Rails per hectare compared to the conventional method. Conclusions Results showed that the average of yield of the first year was significantly greater than that of the second year. Results indicated that use of B4 lead to the highest of yield 2672 kg ha-1. But in terms of plant height no significance was found. The results of technical and economic comp ration comparison indicated that the added net income from B4, was 4940 thousand Rails per hectare compared to the conventional method. Therefore, considering many factors, the Agromaster drill tested in this study was found to be the best suited planter and therefore is recommended for canola planting in the region.

Electron cyclotron current drive predictions for ITER: Comparison of different models

International Nuclear Information System (INIS)

Marushchenko, N.B.; Maassberg, H.; Beidler, C.D.; Turkin, Yu.

2007-01-01

Full text: Due to its high localization and operational flexibility, Electron Cyclotron Current Drive (ECCD) is envisaged for stabilizing the Neoclassical Tearing Mode (NTM) in tokamaks and correcting the rotational transform profile in stellarators. While the spatial location of the electron cyclotron resonant interaction is usually calculated by the ray-tracing technique, numerical tools for calculating the ECCD efficiency are not so common. Two different methods are often applied: i) direct calculation by Fokker-Planck modelling, and ii) by the adjoint approach technique. In the present report we analyze and compare different models used in the adjoint approach technique from the point of view of ITER applications. The numerical tools for calculating the ECCD efficiency developed to date do not completely cover the range of collisional regimes for the electrons involved in the current drive. Only two opposite limits are well developed, collisional and collisionless. Nevertheless, for the densities and temperatures expected for ECCD application in ITER, the collisionless limit model (with trapped particles taken into account) is quite suitable. We analyze the requisite ECCD scenarios with help of the new ray tracing code TRAVIS with the adjoint approach implemented. The (adjoint) Green's function applied for the current drive calculations is formulated with momentum conservation taken into account; this is especially important and even crucial for scenarios, in which mainly bulk electrons are responsible for absorption of the RF power. For comparison, the most common 'high speed limit' model in which the collision operator neglects the integral part and which is approximated by terms valid only for the tail electrons, produces an ECCD efficiency which is an underestimate for some cases by a factor of about 2. In order to select the appropriate model, a rough criterion of 'high speed limit' model applicability is formulated. The results are verified also by

Cardiac auscultation training of medical students: a comparison of electronic sensor-based and acoustic stethoscopes

Directory of Open Access Journals (Sweden)

Jensen Torstein

2005-05-01

Full Text Available Abstract Background To determine whether the use of an electronic, sensor based stethoscope affects the cardiac auscultation skills of undergraduate medical students. Methods Forty eight third year medical students were randomized to use either an electronic stethoscope, or a conventional acoustic stethoscope during clinical auscultation training. After a training period of four months, cardiac auscultation skills were evaluated using four patients with different cardiac murmurs. Two experienced cardiologists determined correct answers. The students completed a questionnaire for each patient. The thirteen questions were weighted according to their relative importance, and a correct answer was credited from one to six points. Results No difference in mean score was found between the two groups (p = 0.65. Grading and characterisation of murmurs and, if present, report of non existing murmurs were also rated. None of these yielded any significant differences between the groups. Conclusion Whether an electronic or a conventional stethoscope was used during training and testing did not affect the students' performance on a cardiac auscultation test.

Low LET radiolysis escape yields for reducing radicals and H2 in pressurized high temperature water

Science.gov (United States)

Sterniczuk, Marcin; Yakabuskie, Pamela A.; Wren, J. Clara; Jacob, Jasmine A.; Bartels, David M.

2016-04-01

Low Linear Energy Transfer (LET) radiolysis escape yields (G values) are reported for the sum (G(radH)+G(e-)aq) and for G(H2) in subcritical water up to 350 °C. The scavenger system 1-10 mM acetate/0.001 M hydroxide/0.00048 M N2O was used with simultaneous mass spectroscopic detection of H2 and N2 product. Temperature-dependent measurements were carried out with 2.5 MeV electrons from a van de Graaff accelerator, while room temperature calibration measurements were done with a 60Co gamma source. The concentrations and dose range were carefully chosen so that initial spur chemistry is not perturbed and the N2 product yield corresponds to those reducing radicals that escape recombination in pure water. In comparison with a recent review recommendation of Elliot and Bartels (AECL report 153-127160-450-001, 2009), the measured reducing radical yield is seven percent smaller at room temperature but in fairly good agreement above 150 °C. The H2 escape yield is in good agreement throughout the temperature range with several previous studies that used much larger radical scavenging rates. Previous analysis of earlier high temperature measurements of Gesc(radOH) is shown to be flawed, although the actual G values may be nearly correct. The methodology used in the present report greatly reduces the range of possible error and puts the high temperature escape yields for low-LET radiation on a much firmer quantitative foundation than was previously available.

Influence of excitonic effects on luminescence quantum yield in silicon

Energy Technology Data Exchange (ETDEWEB)

Sachenko, A.V.; Kostylyov, V.P.; Vlasiuk, V.M. [V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41 prospect Nauky, 03028 Kyiv (Ukraine); Sokolovskyi, I.O., E-mail: isokolovskyi@mun.ca [V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41 prospect Nauky, 03028 Kyiv (Ukraine); Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John' s, NL, A1B 3X7 Canada (Canada); Evstigneev, M. [Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John' s, NL, A1B 3X7 Canada (Canada)

2017-03-15

Nonradiative exciton lifetime in silicon is determined by comparison of the experimental and theoretical curves of bulk minority charge carriers lifetime on doping and excitation levels. This value is used to analyze the influence of excitonic effects on internal luminescence quantum yield at room temperature, taking into account both nonradiative and radiative exciton lifetimes. A range of Shockley-Hall-Reed lifetimes is found, where excitonic effects lead to an increase of internal luminescence quantum yield.

Influence of surface topography on the sputtering yields of silver

International Nuclear Information System (INIS)

Pan Jisheng; Wang Zhenxia; Tao Zhenlan; Zhang Jiping

1992-01-01

The sputtering yields of silver have been measured as a function of the fluence of incident Ar + ions (27 keV) using the collector technique and RBS analysis. The irradiated surface was examined by scanning electron microscopy (SEM). It is shown that the sputtering yields of surfaces with topography are enhanced relative to smooth surfaces of silver, but the extent of the enhancement depends on the irradiation dose. The experimental results can be explained assuming that the surface topography and sputtering yield are a function of incident angle. It is obvious that the surface topography is an important factor to influence the sputtering yield. The term ''apparent sputtering yield'' has specifically been used when referring to the experimental sputtering yield of a surface with topography, to emphasize the difference with a smooth surface. (orig.)

ZNJPrice/Earnings Ratio Model through Dividend Yield and Required Yield Above Expected Inflation

Directory of Open Access Journals (Sweden)

Emil Mihalina

2010-07-01

Full Text Available Price/earnings ratio is the most popular and most widespread evaluation model used to assess relative capital asset value on financial markets. In functional terms, company earnings in the very long term can be described with high significance. Empirically, it is visible from long-term statistics that the demanded (required yield on capital markets has certain regularity. Thus, investors first require a yield above the stable inflation rate and then a dividend yield and a capital increase caused by the growth of earnings that influence the price, with the assumption that the P/E ratio is stable. By combining the Gordon model for current dividend value, the model of market capitalization of earnings (price/earnings ratio and bearing in mind the influence of the general price levels on company earnings, it is possible to adjust the price/earnings ratio by deriving a function of the required yield on capital markets measured by a market index through dividend yield and inflation rate above the stable inflation rate increased by profit growth. The S&P 500 index for example, has in the last 100 years grown by exactly the inflation rate above the stable inflation rate increased by profit growth. The comparison of two series of price/earnings ratios, a modelled one and an average 7-year ratio, shows a notable correlation in the movement of two series of variables, with a three year deviation. Therefore, it could be hypothesized that three years of the expected inflation level, dividend yield and profit growth rate of the market index are discounted in the current market prices. The conclusion is that, at the present time, the relationship between the adjusted average price/earnings ratio and its effect on the market index on one hand and the modelled price/earnings ratio on the other can clearly show the expected dynamics and course in the following period.

The Tynode: A new vacuum electron multiplier

Energy Technology Data Exchange (ETDEWEB)

Graaf, Harry van der, E-mail: vdgraaf@nikhef.nl [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Akhtar, Hassan; Budko, Neil; Chan, Hong Wah; Hagen, Cornelis W. [Delft University of Technology, Delft (Netherlands); Hansson, Conny C.T. [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Nützel, Gert; Pinto, Serge D. [Photonis, Roden (Netherlands); Prodanović, Violeta; Raftari, Behrouz; Sarro, Pasqualina M. [Delft University of Technology, Delft (Netherlands); Sinsheimer, John; Smedley, John [Brookhaven National Laboratory, Upton, NY 11973 (United States); Tao, Shuxia [Eindhoven University of Technology/DIFFER (Netherlands); Theulings, Anne M.M.G. [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Vuik, Kees [Delft University of Technology, Delft (Netherlands)

2017-03-01

By placing, in vacuum, a stack of transmission dynodes (tynodes) on top of a CMOS pixel chip, a single free electron detector could be made with outstanding performance in terms of spatial and time resolution. The essential object is the tynode: an ultra thin membrane, which emits, at the impact of an energetic electron on one side, a multiple of electrons at the other side. The electron yields of tynodes have been calculated by means of GEANT-4 Monte Carlo simulations, applying special low-energy extensions. The results are in line with another simulation based on a continuous charge-diffusion model. By means of Micro Electro Mechanical System (MEMS) technology, tynodes and test samples have been realized. The secondary electron yield of several samples has been measured in three different setups. Finally, several possibilities to improve the yield are presented.

Energetic particles detected by the Electron Reflectometer instrument on the Mars Global Surveyor, 1999-2006

DEFF Research Database (Denmark)

Delory, Gregory T.; Luhmann, Janet G.; Brain, David

2012-01-01

events at Mars associated with solar flares and coronal mass ejections, which includes the identification of interplanetary shocks. MGS observations of energetic particles at varying geometries between the Earth and Mars that include shocks produced by halo, limb, and backsided events provide a unique......We report the observation of galactic cosmic rays and solar energetic particles by the Electron Reflectometer instrument aboard the Mars Global Surveyor (MGS) spacecraft from May of 1999 to the mission conclusion in November 2006. Originally designed to detect low-energy electrons, the Electron...... recorded high energy galactic cosmic rays with similar to 45% efficiency. Comparisons of this data to galactic cosmic ray proton fluxes obtained from the Advanced Composition Explorer yield agreement to within 10% and reveal the expected solar cycle modulation as well as shorter timescale variations. Solar...

Scex 3 and Electron Echo 7, a Comparison of Data from Two Rocket Experiments.

Science.gov (United States)

Bale, Stuart Douglas

Results from two separate active sounding rocket experiments are presented and discussed. The SCEX III sounding rocket (NASA 39.002 UE) and Electron Echo 7 (NASA 36.015) were both launched from the Poker Flat Research Range (65.1^circ N, 147.5^circ W) near Fairbanks, Alaska, on 1 February, 1990 and 9 February, 1988, respectively. Each payload was equipped with an electron accelerator to study both natural and beam-related plasma phenomena. Data from the SCEX III retarding potential analyzer (RPA) and 3805 A and 3914 A photometers show evidence of a plasma discharge process occurring concomitant with operation of the electron gun. This appears as an enhanced electron current, nonlinear with gun injection current, in the RPA. The photometers register a sharp increase in luminosity during full current electron injection. This luminosity is an indicator of the ionizing electron-neutral collisions which liberate electrons and lead to the cascade-type discharge process. These observations are used to attempt to infer the mechanism of electron acceleration which leads to the discharge process. Before the electron gun was activated, the SCEX III payload flew through a region of auroral activity as evidenced by ground-based all-sky TV and energetic particle flux in the forward payload RPA. During this time, low frequency (10 Hz) electrostatic waves were observed in the DC receivers and Langmuir probe instrument. This data is analyzed, with a cross-spectral technique, and an approximate wave number is inferred. Comparison with theory suggests that the observed wave is the electrostatic ion cyclotron mode (EIC) operating on a heavy ion species (NO or O _2). The Echo 7 nose payload, carrying a plasma wave receiver, was ejected upfield of the main electron gun -equipped payload. Data from the swept frequency analyzer experiment provide wave amplitudes, at frequencies up to 15 MHz, as a function of separation of the main and nose payloads. These observations, and the wave modes

Comparison of carcass yield and meat composition of three classes ...

African Journals Online (AJOL)

This study was designed to compare the carcass yield and meat composition of three classes of chicken. Twenty one (21) birds in total consisting of 7 birds each of broilers, cockerel and spent hens were purchased from a reputable farm in Aiyepe, Ogun State. Birds were acclimatized for two weeks under similar ...

Avoiding fractional electrons in subsystem DFT based ab-initio molecular dynamics yields accurate models for liquid water and solvated OH radical

International Nuclear Information System (INIS)

Genova, Alessandro; Pavanello, Michele; Ceresoli, Davide

2016-01-01

In this work we achieve three milestones: (1) we present a subsystem DFT method capable of running ab-initio molecular dynamics simulations accurately and efficiently. (2) In order to rid the simulations of inter-molecular self-interaction error, we exploit the ability of semilocal frozen density embedding formulation of subsystem DFT to represent the total electron density as a sum of localized subsystem electron densities that are constrained to integrate to a preset, constant number of electrons; the success of the method relies on the fact that employed semilocal nonadditive kinetic energy functionals effectively cancel out errors in semilocal exchange–correlation potentials that are linked to static correlation effects and self-interaction. (3) We demonstrate this concept by simulating liquid water and solvated OH • radical. While the bulk of our simulations have been performed on a periodic box containing 64 independent water molecules for 52 ps, we also simulated a box containing 256 water molecules for 22 ps. The results show that, provided one employs an accurate nonadditive kinetic energy functional, the dynamics of liquid water and OH • radical are in semiquantitative agreement with experimental results or higher-level electronic structure calculations. Our assessments are based upon comparisons of radial and angular distribution functions as well as the diffusion coefficient of the liquid.

Avoiding fractional electrons in subsystem DFT based ab-initio molecular dynamics yields accurate models for liquid water and solvated OH radical.

Science.gov (United States)

Genova, Alessandro; Ceresoli, Davide; Pavanello, Michele

2016-06-21

In this work we achieve three milestones: (1) we present a subsystem DFT method capable of running ab-initio molecular dynamics simulations accurately and efficiently. (2) In order to rid the simulations of inter-molecular self-interaction error, we exploit the ability of semilocal frozen density embedding formulation of subsystem DFT to represent the total electron density as a sum of localized subsystem electron densities that are constrained to integrate to a preset, constant number of electrons; the success of the method relies on the fact that employed semilocal nonadditive kinetic energy functionals effectively cancel out errors in semilocal exchange-correlation potentials that are linked to static correlation effects and self-interaction. (3) We demonstrate this concept by simulating liquid water and solvated OH(•) radical. While the bulk of our simulations have been performed on a periodic box containing 64 independent water molecules for 52 ps, we also simulated a box containing 256 water molecules for 22 ps. The results show that, provided one employs an accurate nonadditive kinetic energy functional, the dynamics of liquid water and OH(•) radical are in semiquantitative agreement with experimental results or higher-level electronic structure calculations. Our assessments are based upon comparisons of radial and angular distribution functions as well as the diffusion coefficient of the liquid.

Sputtering of thin and intermediately thick films of solid deuterium by keV electrons

DEFF Research Database (Denmark)

Svendsen, Winnie Edith; Thestrup Nielsen, Birgitte; Schou, Jørgen

1995-01-01

Sputtering of films of solid deuterium by keV electrons was studied in a cryogenic set-up. The sputtering yield shows a minimum yield of about 4 D2/electron for 1.5 and 2 keV electrons at a thickness slightly larger than the average projected range of the electrons. We suggest that the yield around...... the minimum represents the value closest to a bulk-yield induced by electron bombardment. It may also include contributions from the mechanisms that enhance the yield for thin and very thick films....

Degradation of carrageenan by low energy electron accelerator

International Nuclear Information System (INIS)

Relleve, L.; Aranilla, C.; Abad, L.; Dela Rosa, A.; Nagasawa, Naotsugu; Yagi, Toshiaki; Kume, Tamikazu; Yoshii, Fumio

2004-01-01

Degradation of κ-carrageenan using vessel-type low energy electron accelerator was investigated. Carrageenan with different molecular weights were obtained from irradiation of high molecular weight (HMW) and low molecular weight (LMW) κ-carrageenan. Other results presented were obtained from degradation studies of carrageenan by gamma rays. The decrease in molecular weight was accompanied by partial desulfation. From comparison of radiation degradation yield (Gd), it was found that the susceptibility to radiation of the three types of carrageenans in aqueous/gel forms follows the order of λ->ι->>κ- and could have been influenced by their conformational state. κ-carrageenan with molecular weight of ca. 10,000 showed strong growth promotion effect for potato in tissue culture. (author)

Comparison of precipitating electron energy flux on March 22, 1979 with an empirical model: CDAW-6

International Nuclear Information System (INIS)

Simons, S.L. Jr.; Reiff, P.H.; Spiro, R.W.; Hardy, D.A.; Kroehl, H.W.

1985-01-01

Data recorded by Defense Meterological Satellite Program, TIROS and P-78-1 satellites for the CDAW 6 event on March 22, 1979, have been compared with a statistical model of precipitating electron fluxes. Comparisons have been made on both an orbit-by-orbit basis and on a global basis by sorting and binning the data by AE index, invariant latitude and magnetic local time in a manner similar to which the model was generated. We conclude that the model flux agrees with the data to within a factor of two, although small features and the exact locations of features are not consistently reproduced. In addition, the latitude of highest electron precipitation usually occurs about 3 0 more pole-ward in the model than in the data. We attribute this discrepancy to ring current inflation of the storm time magnetosphere (as evidenced by negative Dst's). We suggest that a similar empirical model based on AL instead of AE and including some indicator of the history of the event would provide an even better comparison. Alternatively, in situ data such as electrojet location should be used routinely to normalize the latitude of the auroral precipitation

Swift heavy ion induced electron emission from solids

International Nuclear Information System (INIS)

Rothard, Hermann; Gervais, Benoit; Lanzanò, Gaetano; De Filippo, Enrico; Caron, Michel; Beuve, Michael

2015-01-01

We briefly summarize the results of numerous experiments performed at GANIL aimed at measuring electron yields and doubly differential yields (energy or velocity spectra at different ejection angles, angular distributions). These studies, supported by theoretical investigations and numerical simulations, contributed decisively to our understanding of the very first step in energy deposition in matter, i.e. ionization and subsequent electron transport through condensed matter. The emitted electron spectrum contains a rich variety of features including binary encounter electrons (BEE), convoy electrons (CE), Auger electrons (AE) and the low-energy peak of “secondary” electrons (SE). (paper)

Genome-wide identification of QTL for seed yield and yield-related traits and construction of a high-density consensus map for QTL comparison in Brassica napus

Directory of Open Access Journals (Sweden)

Weiguo eZhao

2016-01-01

Full Text Available Seed yield (SY is the most important trait in rapeseed, which was determined by multiple seed yield-related traits (SYRTs and also easily subject to environmental influence. Lots of quantitative trait loci (QTL for SY and SYRTs were reported in Brassica napus. However, no studies have focused on SY and seven agronomic traits affecting SY simultaneous. Genome-wide QTL analysis for SY and seven SYRTs in eight environments was conducted in a doubled haploid population containing 348 lines. Totally, 18 and 208 QTLs for SY and SYRTs were observed, respectively, and then these QTLs were integrated into 144 consensus QTLs by a meta-analysis. Three major QTLs for SY were observed, including cqSY-C6-2 and cqSY-C6-3 that expressed stably in winter cultivation area for three years and cqSY-A2-2 only expressed in spring rapeseed area. Trait-by-trait meta-analysis revealed that the 144 consensus QTLs were integrated into 72 pleiotropic unique QTLs. Among them, all the unique QTLs affected SY, except for uq-A6-1, including uq.A2-3, uq.C1-2, uq.C1-3, uq.C6-1, uq.C6-5 and uq.C6-6 could also affect more than two SYRTs. According to high density consensus map construction and QTL comparison from literature, 36 QTLs from five populations were co-localized with QTLs identified in this study. In addition, 13 orthologs genes were observed, including five each genes for SY and SW, one each gene for BY, BH and PH, respectively. The genomic information of these QTLs would be valuable in hybrid cultivar breeding, and be helpful to analyze QTL expression in different environments.

Comparison of HSPF and SWAT models performance for runoff and sediment yield prediction.

Science.gov (United States)

Im, Sangjun; Brannan, Kevin M; Mostaghimi, Saied; Kim, Sang Min

2007-09-01

A watershed model can be used to better understand the relationship between land use activities and hydrologic/water quality processes that occur within a watershed. The physically based, distributed parameter model (SWAT) and a conceptual, lumped parameter model (HSPF), were selected and their performance were compared in simulating runoff and sediment yields from the Polecat Creek watershed in Virginia, which is 12,048 ha in size. A monitoring project was conducted in Polecat Creek watershed during the period of October 1994 to June 2000. The observed data (stream flow and sediment yield) from the monitoring project was used in the calibration/validations of the models. The period of September 1996 to June 2000 was used for the calibration and October 1994 to December 1995 was used for the validation of the models. The outputs from the models were compared to the observed data at several sub-watershed outlets and at the watershed outlet of the Polecat Creek watershed. The results indicated that both models were generally able to simulate stream flow and sediment yields well during both the calibration/validation periods. For annual and monthly loads, HSPF simulated hydrologic and sediment yield more accurately than SWAT at all monitoring sites within the watershed. The results of this study indicate that both the SWAT and HSPF watershed models performed sufficiently well in the simulation of stream flow and sediment yield with HSPF performing moderately better than SWAT for simulation time-steps greater than a month.

Determination of the energy of suprathermal electrons during lower hybrid current drive on PBX-M

International Nuclear Information System (INIS)

von Goeler, S.; Bernabei, S.; Davis, W.; Ignat, D.; Kaita, R.; Roney, P.; Stevens, J.; Post-Zwicker, A.

1993-06-01

Suprathermal electrons are diagnosed by a hard x-ray pinhole camera during lower hybrid current drive on PBX-M. The experimental hard x-ray images are compared with simulated images, which result from an integration of the relativistic bremsstrahlung along lines-of-sight through the bean-shaped plasma. Images with centrally peaked and radially hollow radiation profiles are easily distinguished. The energy distribution of the suprathermal electrons is analyzed by comparing images taken with different absorber foils. An effective photon temperature is derived from the experimental images, and a comparison with simulated photon temperatures yields the energy of the suprathermal electrons. The analysis indicates that the energy of the suprathermal electrons in the hollow discharges is in the 50 to 100 key range in the center of the discharge. There seems to exist a very small higher energy component close to the plasma edge

Modification to an Auger Electron Spectroscopy system for measuring segregation in a bi-crystal

International Nuclear Information System (INIS)

Jafta, C J; Roos, W D; Terblans, J J

2013-01-01

It is reported that different crystal surface orientations yield different segregation fluxes. Although there were a few attempts to confirm these predictions experimentally, it is very difficult to compare data without making a few assumptions. Parameters like temperature measurement, crystal history and spectrometer variables are all adding to the complexity of directly comparing the segregation behaviour from one crystal to another. This investigation makes use of a Cu bi-crystal, modifications to the scanning control unit of the AES electron beam to eliminate the difference in experimental parameters and specialized written software to automate the data acquisition process. This makes direct comparison of segregation parameters on two different orientations possible. The paper describes the electron beam modifications, experimental setup and procedures, as well as the software developed to control the electron beam and automate data acquisition.

Secondary electron emission from insulators

International Nuclear Information System (INIS)

Kanaya, K.; Ono, S.; Ishigaki, F.

1978-01-01

The high yield of secondary electron emission from insulators due to electron bombardment may be the result of an increase of the depth of escape. The free-electron scattering theory is applied to the high energy of primary beams, but cannot be applied to the low energy of secondary escaping beams because of the large energy gap of the insulators. The plasmon loss with the valence electron is considered when the secondary electrons escape. Based on the energy retardation power formula of the penetration and energy loss of an electron probe into solid targets, secondary electron emissions from insulators are calculated from the assumptions that the distribution of the secondary electrons due to both incident and back-scattered electrons within the target is isotropic and that it follows the absorption law of the Lenard type. The universal yield-energy curve of the secondary electron emission, which is deduced as a function of three parameters such as ionisation potential, valence electron and the back-scattered coefficient in addition to the free-electron density effect, is found to be in good agreement with the experimental results. (author)

Neutron yield in experiments with Z-pinches in frozen deuterium filaments

International Nuclear Information System (INIS)

Meierovich, B.E.; Sukhorukov, S.T.

1991-01-01

Experiments on the properties of the neutron yield and stability of dense Z-pinches in frozen deuterium filaments two years ago have still not received a proper explanation. A discharge in a dielectric deuterium filament differs qualitatively in its behavior from one in a metal conductor. The authors assert attempts to interpret the experiment have not taken this fact properly into account. The enhanced stability and substantial neutron yield do not follow from the classical picture of a Bennett equilibrium in the current channel. The most important experimental characteristic of a discharge in frozen deuterium is the dependence of the neutron yield on the current strength at a given stage. The spread in the experimental points is quite large so one naturally prefers t describe the experimental data by means of a physically simple model and not go to a full-scale simulation of all the processes. When the deuterium is fully ionized the electron drift velocity is smaller than the thermal velocity, enabling calculation of the neutron yield by means of a self-similar model of the Z-pinch compression which treats electron degeneracy. To find the neutron yield it suffices to consider only the first half-period of the self-similar oscillations including the state of maximum compression. The subsequent evolution of the current channel, which is associated with radial expansion, does not contribute significantly to the neutron yield

Comparison of quantitative trait loci for rice yield, panicle length and ...

Indian Academy of Sciences (India)

2011-08-19

Aug 19, 2011 ... and spikelet density across three connected populations ... 2College of Biosafety Science and Technology Hunan Agricultural University, Changsha 410128, People's .... 6, 7 and 11; the Teqing allele has an increase in yield.

Electronic structure of Pt-Co cathode catalysts in membrane electrolyte assembly observed by X-ray absorption fine structure spectroscopy with different probing depth

International Nuclear Information System (INIS)

Kobayashi, M.; Hidai, S.; Niwa, H.; Harada, Y.; Oshima, M.; Ofuchi, H.; Nakamori, Y.; Aoki, T.

2010-01-01

Electronic structures of Pt-Co cathode and Pt-Ru anode catalysts in membrane electrolyte assemblies (MEAs) for polymer electrolyte fuel cell have been investigated using X-ray absorption near edge structure (XANES) spectroscopy, and the changes of electronic structures accompanied with degradation have been observed by comparison between spectra obtained by fluorescence-yield (FY) and conversion-electron-yield (CEY) methods, probing depths of which are several hundreds μm and ∼100 nm, respectively. The Co K XANES spectra of the as-fabricated MEA show that the Co atoms in the cathode are metallic and oxidized Co ions exist at the interface between the cathode and electrolyte. The spectra of the long-time operated MEA suggest that the oxidation of Co makes progress with degradation of the cathode catalysts. In contrast to the Co K XANES spectra, the line shape of the Ru K XANES spectra is unchanged even after the long-time operation.

A comparison of various Gibbs energy dissipation correlations for predicting microbial growth yields

Energy Technology Data Exchange (ETDEWEB)

Liu, J.-S. [Laboratory of Chemical and Biochemical Engineering, Swiss Federal Institute of Technology, EPFL, CH-1015 Lausanne (Switzerland); Vojinovic, V. [Laboratory of Chemical and Biochemical Engineering, Swiss Federal Institute of Technology, EPFL, CH-1015 Lausanne (Switzerland); Patino, R. [Cinvestav-Merida, Departamento de Fisica Aplicada, Km. 6 carretera antigua a Progreso, AP 73 Cordemex, 97310 Merida, Yucatan (Mexico); Maskow, Th. [UFZ Centre for Environmental Research, Department of Environmental Microbiology, Permoserstrasse 15, D-04318 Leipzig (Germany); Stockar, U. von [Laboratory of Chemical and Biochemical Engineering, Swiss Federal Institute of Technology, EPFL, CH-1015 Lausanne (Switzerland)]. E-mail: urs.vonStockar@epfl.ch

2007-06-25

Thermodynamic analysis may be applied in order to predict microbial growth yields roughly, based on an empirical correlation of the Gibbs energy of the overall growth reaction or Gibbs energy dissipation. Due to the well-known trade-off between high biomass yield and high Gibbs energy dissipation necessary for fast growth, an optimal range of Gibbs energy dissipation exists and it can be correlated to physical characteristics of the growth substrates. A database previously available in the literature has been extended significantly in order to test such correlations. An analysis of the relationship between biomass yield and Gibbs energy dissipation reveals that one does not need a very precise estimation of the latter to predict the former roughly. Approximating the Gibbs energy dissipation with a constant universal value of -500 kJ C-mol{sup -1} of dry biomass grown predicts many experimental growth yields nearly as well as a carefully designed, complex correlation available from the literature, even though a number of predictions are grossly out of range. A new correlation for Gibbs energy dissipation is proposed which is just as accurate as the complex literature correlation despite its dramatically simpler structure.

A comparison of various Gibbs energy dissipation correlations for predicting microbial growth yields

International Nuclear Information System (INIS)

Liu, J.-S.; Vojinovic, V.; Patino, R.; Maskow, Th.; Stockar, U. von

2007-01-01

Thermodynamic analysis may be applied in order to predict microbial growth yields roughly, based on an empirical correlation of the Gibbs energy of the overall growth reaction or Gibbs energy dissipation. Due to the well-known trade-off between high biomass yield and high Gibbs energy dissipation necessary for fast growth, an optimal range of Gibbs energy dissipation exists and it can be correlated to physical characteristics of the growth substrates. A database previously available in the literature has been extended significantly in order to test such correlations. An analysis of the relationship between biomass yield and Gibbs energy dissipation reveals that one does not need a very precise estimation of the latter to predict the former roughly. Approximating the Gibbs energy dissipation with a constant universal value of -500 kJ C-mol -1 of dry biomass grown predicts many experimental growth yields nearly as well as a carefully designed, complex correlation available from the literature, even though a number of predictions are grossly out of range. A new correlation for Gibbs energy dissipation is proposed which is just as accurate as the complex literature correlation despite its dramatically simpler structure

Multiple ionization of noble gases by 2.0 MeV proton impact: comparison with equi-velocity electron impact ionization

International Nuclear Information System (INIS)

Melo, W.S.; Santos, A.C.F.; Sant'Anna, M.M.; Sigaud, G.M.; Montenegro, E.C.

2002-01-01

Absolute single- and multiple-ionization cross sections of rare gases (He, Ne, Ar, Kr and Xe) have been measured for collisions with 2.0 MeV p + . A comparison is made with equi-velocity electron impact ionization cross sections as well as with the available proton impact data. For the light rare gases the single-ionization cross sections are essentially the same for both proton and electron impacts, but increasing differences appear for the heavier targets. (author). Letter-to-the-editor

Real-time yield estimation based on deep learning

Science.gov (United States)

Rahnemoonfar, Maryam; Sheppard, Clay

2017-05-01

Crop yield estimation is an important task in product management and marketing. Accurate yield prediction helps farmers to make better decision on cultivation practices, plant disease prevention, and the size of harvest labor force. The current practice of yield estimation based on the manual counting of fruits is very time consuming and expensive process and it is not practical for big fields. Robotic systems including Unmanned Aerial Vehicles (UAV) and Unmanned Ground Vehicles (UGV), provide an efficient, cost-effective, flexible, and scalable solution for product management and yield prediction. Recently huge data has been gathered from agricultural field, however efficient analysis of those data is still a challenging task. Computer vision approaches currently face diffident challenges in automatic counting of fruits or flowers including occlusion caused by leaves, branches or other fruits, variance in natural illumination, and scale. In this paper a novel deep convolutional network algorithm was developed to facilitate the accurate yield prediction and automatic counting of fruits and vegetables on the images. Our method is robust to occlusion, shadow, uneven illumination and scale. Experimental results in comparison to the state-of-the art show the effectiveness of our algorithm.

Comparative study of electron-impact C(1s) core-excitation processes in C{sub 2} and C{sub 2}N{sub 2} molecules

Energy Technology Data Exchange (ETDEWEB)

Michelin, S.E. [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil)], E-mail: fsc1sem@fsc.ufsc.br; Mazon, K.T.; Arretche, F.; Tenfen, W.; Oliveira, H.L.; Falck, A.S.; Scopel, M.A.; Silva, L.S.S. da [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Fujimoto, M.M. [Departamento de Fisica, Universidade Federal do Parana, 81531-990 Curitiba, PR (Brazil); Iga, I.; Lee, M.-T. [Departamento de Quimica, Universidade Federal de Sao Carlos, 13565-905, Sao Carlos, SP (Brazil)

2009-04-15

Distorted-wave approximation (DWA) is applied to study core-orbital excitations in C{sub 2}and C{sub 2}N{sub 2} molecules by electron impact. More specifically, we report calculated integral cross sections (ICS) for the X{sup 1}{sigma}{sub g}{sup +}{yields}{sup 1,3}{pi}{sub u}(1s{sigma}{sub u}{yields}1p{pi}{sub g}) and X{sup 1}{sigma}{sub g}{sup +}{yields}{sup 1,3}{pi}{sub g}(1s{sigma}{sub g}{yields}1p{pi}{sub g}) transitions in the C{sub 2}, and X{sup 1}{sigma}{sub g}{sup +}{yields}{sup 1,3}{pi}{sub g}(2s{sigma}{sub g}{yields}2p{pi}{sub g}) and X{sup 1}{sigma}{sub g}{sup +}{yields}{sup 1,3}{pi}{sub u}(2s{sigma}{sub u}{yields}2p{pi}{sub g}) transitions in the C{sub 2}N{sub 2} molecules in the 300-800 eV incident energy range. The comparison of the calculated ICS of these targets with the corresponding data for C{sub 2}H{sub 2} presented. Comparison is also made for the theoretical RI(3:1) ratios of these targets which are calculated by dividing the ICS for triplet transitions by the corresponding results for singlet transitions. The similarities and differences of these results, particularly the presence of the shape resonances at near excitation thresholds, are discussed. The influence of the atomic (localized) and molecular (delocalized) characters of the core orbitals on the core-excitation processes is also investigated. In addition, generalized oscillator strengths for the singlet core-orbital transitions are calculated at incident energy of 1290 eV for C{sub 2} and C{sub 2}N{sub 2}. A comparison with the existing theoretical and experimental data for C{sub 2}H{sub 2} is also presented.

Delayed neutron yield from fast neutron induced fission of 238U

International Nuclear Information System (INIS)

Piksaikin, V.M.; Kazakov, L.E.; Isaev, S.G.; Roshchenko, V.A.; Goverdovski, A.A.; Tertytchnyi, R.G.

2002-01-01

The measurements of the total delayed neutron yield from fast neutron induced fission of 238 U were made. The experimental method based on the periodic irradiation of the fissionable sample by neutrons from a suitable nuclear reaction had been employed. The preliminary results on the energy dependence of the total delayed neutron yield from fission of 238 U are obtained. According to the comparison of experimental data with our prediction based on correlation properties of delayed neutron characteristics, it is concluded that the value of the total delayed neutron yield near the threshold of (n,f) reaction is not a constant. (author)

YIELDING AND CONTENT OF SELECTED MICROELEMENTS IN MAIZE FERTILIZED WITH VARIOUS ORGANIC MATERIALS

Directory of Open Access Journals (Sweden)

Jerzy Wieczorek

2017-07-01

On the basis of conducted research it was found that various fertilizer combinations applied in the experiment had a significant influence on the test plant yielding. All compared fertilizer variants allowed maize to produce statistically significantly higher yield in comparison with the yield harvested from the unfertilized soils. Fertilization with sewage sludge I supplemented with mineral treatment and application of solely mineral salts proved the most beneficial for the maize yield. Applied fertilizer combinations affected the content of microelements. The highest concentrations of nickel in maize green mass were assessed in plant samples from the unfertilized object, whereas zinc and copper from mineral fertilization variant. Except of zinc, introducing additional metal doses did not influence their increased content in plant organs. Soil enrichment with zinc contained in sewage sludge I and II (respectively 77.4 mg and 49.9 mg ∙ pot-1 contributed to its elevated concentration in maize roots but at the same time this metal content statistically significantly decreased in maize shoots in comparison with the amounts determined in plants fertilized with mineral materials.

Technological yields of sources for radiation processing

International Nuclear Information System (INIS)

Zagorski, Z.P.

1993-01-01

The present report is prepared for planners of radiation processing of any material. Calculations are focused on accelerators of electrons, divided into two groups: versatile linacs of energy up to 13 MeV, and accelerators of lower energy, below 2 MeV, of better energy yield but of limited applications. The calculations are connected with the confrontation of the author's technological expectations during the preparation of the linac project in the late '60s, with the results of 25 years of exploitation of the machine. One has to realize that from the 200 kW input power from the mains, only 5 kW of bent and scanned beam is recovered on the conveyor. That power is only partially used for radiation induced phenomena, because of the demanded homogeneity of the dose, of the mode of packing of the object and its shape, of edges of the scanned area and in the spaces between boxes, and of loses during the idle time due to the tuning of the machine and dosimetric operations. The use of lower energy accelerators may be more economical than that of linacs in case of objects of specific type. At the first stage already, that is of the conversion of electrical power into that of low energy electron beam, the yield is 2-3 times better than in the case of linacs. Attention has been paid to the technological aspects of electron beam conversion into the more penetrating Bremsstrahlung similar to gamma radiation. The advantages of technologies, which make possible a control of the shape of the processed object are stressed. Special attention is focused to the relation between the yield of processing and the ratio between the maximum to the minimum dose in the object under the irradiation. (author). 14 refs, 14 figs

Analysis of Yield and Yield Related Traits Variability of Winter Wheat (Triticum aestivum L. Cv. Izolda and Double Haploid Lines

Directory of Open Access Journals (Sweden)

Kozdój Janusz

2015-12-01

Full Text Available The yield-forming potential of winter wheat is determined by several factors, namely total number of shoots per plant and total number of spikelets per spike. The field experiments were conducted during three vegetation seasons at the Plant Breeding and Acclimatization Institute – National Research Institute (PBAI–NRI, located in Radzików, Poland. The objective of this study was a comparative analysis of the structural yield-forming factor levels, which determine grain yield per spike and per plant of the DH lines and standard Izolda cultivar. Results indicate that several DH lines showed some differences in tested morphological structures of plant, yield factor levels and in grain yield per spike and per plant in comparison to standard Izolda, regardless of the year. Mean grain yield per plant of DH lines was 26.5% lower in comparison to standard Izolda only in the second year of study. It was caused by a reduction of productive tillers number. Structural yield-forming potential of DH lines was used in 38% and 59% and in case of Izolda in 47% and 61% (the second and the third year of experiment, respectively. The mean grain yield per spike of DH lines was 14.8% lower than Izolda cultivar only in third year of experiment and it was caused by about 12% lower number of grains per spike. Structural yield-forming potential of DH spikes was used in 82.4%, 85.4% and 84.9% and in case of Izolda in 83.8%, 87% and 89.5% (the first, the second and the third year of experiment, respectively. The grain yield per winter wheat plant (both DH lines and standard Izolda was significantly correlated with the number of productive tillers per plant (r = 0.80. The grain yield per winter wheat spike (both DH lines and Izolda cultivar was significantly and highly correlated with the number of grains per spike (r = 0.96, number of fertile spikelets per spike (r = 0.87 and the spike length (r = 0.80. Variation of spike and plant structural yield-forming factors

An in situ Comparison of Electron Acceleration at Collisionless Shocks under Differing Upstream Magnetic Field Orientations

Energy Technology Data Exchange (ETDEWEB)

Masters, A.; Dougherty, M. K. [The Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2AZ (United Kingdom); Sulaiman, A. H. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Stawarz, Ł. [Astronomical Observatory, Jagiellonian University, ul. Orla 171, 30-244 Krakow (Poland); Reville, B. [School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom); Sergis, N. [Office of Space Research and Technology, Academy of Athens, Soranou Efesiou 4, 11527 Athens (Greece); Fujimoto, M. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Burgess, D. [School of Physics and Astronomy, Queen Mary University of London, London E1 4NS (United Kingdom); Coates, A. J., E-mail: a.masters@imperial.ac.uk [Mullard Space Science Laboratory, Department of Space and Climate Physics, University College London, Holmbury St. Mary, Dorking RH5 6NT (United Kingdom)

2017-07-10

A leading explanation for the origin of Galactic cosmic rays is acceleration at high-Mach number shock waves in the collisionless plasma surrounding young supernova remnants. Evidence for this is provided by multi-wavelength non-thermal emission thought to be associated with ultrarelativistic electrons at these shocks. However, the dependence of the electron acceleration process on the orientation of the upstream magnetic field with respect to the local normal to the shock front (quasi-parallel/quasi-perpendicular) is debated. Cassini spacecraft observations at Saturn’s bow shock have revealed examples of electron acceleration under quasi-perpendicular conditions, and the first in situ evidence of electron acceleration at a quasi-parallel shock. Here we use Cassini data to make the first comparison between energy spectra of locally accelerated electrons under these differing upstream magnetic field regimes. We present data taken during a quasi-perpendicular shock crossing on 2008 March 8 and during a quasi-parallel shock crossing on 2007 February 3, highlighting that both were associated with electron acceleration to at least MeV energies. The magnetic signature of the quasi-perpendicular crossing has a relatively sharp upstream–downstream transition, and energetic electrons were detected close to the transition and immediately downstream. The magnetic transition at the quasi-parallel crossing is less clear, energetic electrons were encountered upstream and downstream, and the electron energy spectrum is harder above ∼100 keV. We discuss whether the acceleration is consistent with diffusive shock acceleration theory in each case, and suggest that the quasi-parallel spectral break is due to an energy-dependent interaction between the electrons and short, large-amplitude magnetic structures.

Bright-field scanning confocal electron microscopy using a double aberration-corrected transmission electron microscope

Energy Technology Data Exchange (ETDEWEB)

Wang, Peng; Behan, Gavin; Kirkland, Angus I. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Nellist, Peter D., E-mail: peter.nellist@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Cosgriff, Eireann C.; D' Alfonso, Adrian J.; Morgan, Andrew J.; Allen, Leslie J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Hashimoto, Ayako [Advanced Nano-characterization Center, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba 305-0003 (Japan); Takeguchi, Masaki [Advanced Nano-characterization Center, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba 305-0003 (Japan); High Voltage Electron Microscopy Station, NIMS, 3-13 Sakura, Tsukuba 305-0003 (Japan); Mitsuishi, Kazutaka [Advanced Nano-characterization Center, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba 305-0003 (Japan); Quantum Dot Research Center, NIMS, 3-13 Sakura, Tsukuba 305-0003 (Japan); Shimojo, Masayuki [High Voltage Electron Microscopy Station, NIMS, 3-13 Sakura, Tsukuba 305-0003 (Japan); Advanced Science Research Laboratory, Saitama Institute of Technology, 1690 Fusaiji, Fukaya 369-0293 (Japan)

2011-06-15

Scanning confocal electron microscopy (SCEM) offers a mechanism for three-dimensional imaging of materials, which makes use of the reduced depth of field in an aberration-corrected transmission electron microscope. The simplest configuration of SCEM is the bright-field mode. In this paper we present experimental data and simulations showing the form of bright-field SCEM images. We show that the depth dependence of the three-dimensional image can be explained in terms of two-dimensional images formed in the detector plane. For a crystalline sample, this so-called probe image is shown to be similar to a conventional diffraction pattern. Experimental results and simulations show how the diffracted probes in this image are elongated in thicker crystals and the use of this elongation to estimate sample thickness is explored. -- Research Highlights: {yields} The confocal probe image in a scanning confocal electron microscopy image reveals information about the thickness and height of the crystalline layer. {yields} The form of the contrast in a three-dimensional bright-field scanning confocal electron microscopy image can be explained in terms of the confocal probe image. {yields} Despite the complicated form of the contrast in bright-field scanning confocal electron microscopy, we see that depth information is transferred on a 10 nm scale.

The Effect of Mycorrhizal Fungi and Humic Acid on Yield and Yield Components of Sunflower

Directory of Open Access Journals (Sweden)

Hamideh Veysi

2017-08-01

Full Text Available Introduction Cultivated sunflower is one of the largest oilseed crops in the world. Sunflower seed is the third largest source of vegetable oil worldwide, following soybean and canola. Nitrogen is one of the most important elements for crops to achieve optimum yields and quality. Phosphorus (P, next to nitrogen, is often the most limiting nutrient for crop and forage production. Phosphorus availability is controlled by three primary factors: soil pH, amount of organic matter and plant species (Reddy et al., 2003. Arbuscular mycorrhizal fungi are one of the most important microorganisms in majority of the undamaged soils so that about 70% of the soil microbial biomass is formed by the mycelium of these fungi. Mycorrhizal association promotes plant absorption of scarce or immobile minerals, especially phosphorus, resulting in enhanced plant growth. Humic acids are dark brown to black, and are soluble in waterunder neutral and alkaline conditions. They are complex aromatic macromolecules with amino acid, amino sugar, peptide and aliphatic compounds linked to the aromatic groups. Humic acid contains nitrogen, phosphorous, calcium, magnesium, sulphur, copper and zinc (Subramanian et al., 2009. Materials and methods Experiment was conducted as split plot factorial based on randomized block design with three replications in 2011-2012. The main plots consisted of nitrogen and phosphorus application levels (zero percent or no chemical fertilizer application, 50% equivalent to 37.5 kg.ha-1 urea + 25 kg.ha-1 super phosphate triple and 100% equivalent to 75 kg.ha-1 urea + 25 kg.ha-1 super phosphate triple. Two species of mycorrhizal include (G. mosseae and (G. interaradices with three levels of humic acid (0, 8 and 16 kg.ha-1 were placed in subplots. The measured traits were: plant height, seed number per head, head diameter, seed oil content, thousand seed weight and seed yield. The data were analyzed using the Mstat-C statistical software. Mean comparison

Yield advantage and water saving in maize/pea intercrop

NARCIS (Netherlands)

Mao, L.; Zhang, L.; Li, W.; Werf, van der W.; Sun, J.; Spiertz, J.H.J.; Li, L.

2012-01-01

Intercropping is a well-established strategy for maximization of yield from limited land, but mixed results have been obtained as to its performance in terms of water use efficiency. Here, two maize/pea intercrop layouts were studied in comparison to sole maize and sole pea with and without plastic

Electron Cloud Parameterization Studies in the LHC

CERN Document Server

Dominguez, O; Baglin, V; Bregliozzi, G; Jimenez, J M; Metral, E; Rumolo, G; Schulte, D; Zimmermann, F

2011-01-01

During LHC beam commissioning with 150, 75 and 50-ns bunch spacing, important electron-cloud effects, like pressure rise, cryogenic heat load, beam instabilities or emittance growth, were observed. The main strategy to combat the LHC electron cloud, defined about ten years ago, relies on the surface conditioning arising from the chamber-surface bombardment with cloud electrons. In a standard model, the conditioning state of the beam-pipe surface is characterized by three parameters: 1. most importantly, the secondary emission yield δmax; 2. the incident electron energy at which the yield is maximum, ε_max; and 3. the probability of elastic reflection of low-energy primary electrons hitting the chamber wall, R. Since at the LHC no in-situ secondary-yield measurements are available, we compare the relative local pressure-rise measurements taken for different beam configurations against simulations in which surface parameters are scanned. This benchmarking of measurements and simulations is used to infer the s...

Ionization of xenon by electrons: Partial cross sections for single, double, and triple ionization

International Nuclear Information System (INIS)

Mathur, D.; Badrinathan, C.

1987-01-01

High-sensitivity measurements of relative partial cross sections for single, double, and triple ionization of Xe by electron impact have been carried out in the energy region from threshold to 100 eV using a crossed-beam apparatus incorporating a quadrupole mass spectrometer. The weighted sum of the relative partial cross sections at 50 eV are normalized to the total ionization cross section of Rapp and Englander-Golden to yield absolute cross-section functions. Shapes of the partial cross sections for single and double ionization are difficult to account for within a single-particle picture. Comparison of the Xe + data with 4d partial photoionization cross-section measurements indicates the important role played by many-body effects in describing electron-impact ionization of high-Z atoms

Effect of heavy tempering on microstructure and yield strength of 28CrMo48VTiB martensitic steel

Science.gov (United States)

Sun, Yu; Gu, Shunjie; Wang, Qian; Wang, Huibin; Wang, Qingfeng; Zhang, Fucheng

2018-02-01

The 28CrMo48VTiB martensitic steel for sulfide stress cracking (SSC) resistance oil country tubular goods (OCTG) of C110 grade was thermally processed through quenching at 890 °C and tempering at 600 °C-720 °C for 30-90 min. The microstructures of all samples were characterized using field emission scanning electron microscopy (FESEM), electron backscattering diffraction (EBSD), transmission electron microscopy (TEM) and x-ray diffractometry (XRD). Also, the tensile properties were measured. The results indicated that the yield strength (YS) decreased as both the tempering temperature and duration increased, due to the coarsening of martensitic packet/block/lath structures, the reduction of dislocation density, as well as the increase of both the volume fraction and average diameter of the precipitates. The martensitic lath width was the key microstructural parameter controlling the YS of this heavily-tempered martensitic steel, whereas the corresponding relationship was in accordance with the Langford-Cohen model. Furthermore, the martensitic structure boundary and the solid solution strengthening were the two most significant factors dominating the YS, in comparison with the dislocation and precipitation strengthening.

Comparison of collisionless macroscopic models and application to the ion-electron instability

International Nuclear Information System (INIS)

Ahedo, E.; Lapuerta, V.

2001-01-01

In a first part, different macroscopic models of linear Landau damping are compared using a concise one-dimensional (1-D) collisionless formulation. The three-moment model of Chang and Callen (CC) [Phys. Fluids B 4, 1167 (1992)] with two closure relations (complex in the Fourier space) for the viscous stress and the heat conduction is found to be equivalent to the two-moment model of Stubbe-Sukhorukov (SS) [Phys. Plasmas 6, 2976 (1999)], which uses a single (complex) closure relation for the pressure. The comparison of the respective closure relations favors clearly the SS pressure law, which associates an anomalous resistivity to the Landau damping. In a second part, a macroscopic interpretation, with the SS model, of the ion-electron instability shows its resistive character for low and intermediate drift velocities, and the transition to the reactive Buneman limit. The pressure law for the electrons is found to verify a simple law, whereas approximate laws are discussed for the ion pressure. These laws are used to close a macroscopic model for stability analyses of nonhomogeneous plasma structures, where SS and CC models are not applicable easily

Yields of Radionuclides Created by Photonuclear Reactions on Be, C, Na, Cl, and Ge, Using Bremsstrahlung of 150-MeV Electrons

International Nuclear Information System (INIS)

Dickens, J.K.

2001-01-01

The bremsstrahlung created by 150-MeV electrons impinging on a tantalum radiator was used to study photonuclear reactions on samples containing Be, C, Na, Cl and Ge. For Ge fifteen radioisotopes, ranging in half life between 2.6 min and 271 days, and in mass between 65 and 75, were obtained in sufficient amount to determine their yields quantitatively using known decay gamma-rays. Special equipment is described which was developed to create the bremsstrahlung using a beam-sharing mode, while minimizing the neutron flux on the sample. Relative production rates were determined. These were analyzed to provide absolute average cross sections for production of three reactions

Radiative corrections in K{yields}{pi}l{sup +}l{sup -} decays

Energy Technology Data Exchange (ETDEWEB)

Kubis, Bastian; Schmidt, Rebekka [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Bonn (Germany)

2010-11-15

We calculate radiative corrections to the flavor-changing neutral current process K{yields}{pi}l {sup +}l{sup -}, both for charged and neutral kaon decays. While the soft-photon approximation is shown to work well for the muon channels, we discuss the necessity of further phase space cuts with electrons in the final state. It is also shown how to transfer our results to other decays such as {eta}{yields}{gamma}l{sup +} l{sup -} or {omega}{yields}{pi}{sup 0}l{sup +}l{sup -}. (orig.)

Comparison of energy and yield parameters in maize crop

International Nuclear Information System (INIS)

Memon, S.Q.; Mirjat, M.S.; Amjad, N.

2013-01-01

The aim of this study was to determine direct and indirect input energy in maize production and to investigate the efficiency of energy consumption in maize crop. Result showed that emergence percent, plant height, number of grains per cob and grain yield were the highest in deep tillage as compared to conventional and zero tillage. Total energy input and output were the highest in deep tillage with NPK at the rate 150-75-75kg/ha. The net energy gain was found the highest in deep tillage followed by conventional tillage and the lowest net energy gain in zero tillage. (author)

Target size analysis of bioactive substances by radiation inactivation. Comparison with electron beam and. gamma. -ray

Energy Technology Data Exchange (ETDEWEB)

Kume, Tamikazu; Watanabe, Yuhei; Ishigaki, Isao; Hirose, Shigehisa

1988-11-01

The molecular sizes of various bioactive substances can be measured by the radiation inactivation method. The high energy electron beam (10 MeV) and /sup 60/Co-..gamma.. ray are mainly used for radiation inactivation method. When the practical electron accelerator (/similar to/ 3 MeV) is used for the method, the problems such as penetration and increase of temperature will arise. In this paper the radiation inactivation using 3MeV electron beam is investigated by comparison with ..gamma..-ray. When the plate type glass ampules (glass thickness 1 +- 0.1 mm) were used as the irradiation vessels, relatively uniform dose distribution was obtained. The temperature increased only from 21 degC to 35 degC by irradiation (0.77 mA, 100 passes, 100 kGy). Under the irradiation condition mentioned above, the molecular size of three enzymes were calculated from D/sub 37/ doses. The molecular sizes obtained by electron beam and ..gamma..-ray were 14,000 and 17,000 respectively for lysozyme, 33,000 for pepsin, and 191,000 and 164,000 for yeast alcohol dehydrogenase. These values agreed closely with the reported molecular weight, suggesting that the 3 MeV electron beam can also be used for the radiation inactivation under limited conditions.

Comparison of the secondary electrons produced by proton and electron beams in water

Energy Technology Data Exchange (ETDEWEB)

Kia, Mohammad Reza, E-mail: m-r-kia@aut.ac.ir; Noshad, Houshyar [Department of Energy Engineering and Physics, Amirkabir University of Technology (Tehran Polytechnic), P.O. Box 15875-4413, Hafez Avenue, Tehran (Iran, Islamic Republic of)

2016-05-15

The secondary electrons produced in water by electron and proton beams are compared with each other. The total ionization cross section (TICS) for an electron impact in water is obtained by using the binary-encounter-Bethe model. Hence, an empirical equation based on two adjustable fitting parameters is presented to determine the TICS for proton impact in media. In order to calculate the projectile trajectory, a set of stochastic differential equations based on the inelastic collision, elastic scattering, and bremsstrahlung emission are used. In accordance with the projectile trajectory, the depth dose deposition, electron energy loss distribution in a certain depth, and secondary electrons produced in water are calculated. The obtained results for the depth dose deposition and energy loss distribution in certain depth for electron and proton beams with various incident energies in media are in excellent agreement with the reported experimental data. The difference between the profiles for the depth dose deposition and production of secondary electrons for a proton beam can be ignored approximately. But, these profiles for an electron beam are completely different due to the effect of elastic scattering on electron trajectory.

Simulation of the electron collection efficiency of a PMT based on the MCP coated with high secondary yield material

Energy Technology Data Exchange (ETDEWEB)

Chen, Lin, E-mail: chenlin@opt.cn [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi' an 710119 (China); Graduate School of Chinese Academy of Sciences (CAS), Beijing 100049 (China); Xi' an Jiaotong University, Xi' an 710049 (China); Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006 (China); Tian, Jinshou [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi' an 710119 (China); Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006 (China); Zhao, Tianchi [Institute of High Energy Physics (IHEP) of CAS, Beijing 100049 (China); Liu, Chunliang [Xi' an Jiaotong University, Xi' an 710049 (China); Liu, Hulin; Wei, Yonglin; Sai, Xiaofeng [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi' an 710119 (China); Chen, Ping [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi' an 710119 (China); Graduate School of Chinese Academy of Sciences (CAS), Beijing 100049 (China); Wang, Xing; Lu, Yu [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi' an 710119 (China); Hui, Dandan [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi' an 710119 (China); Graduate School of Chinese Academy of Sciences (CAS), Beijing 100049 (China)

2016-11-01

Owning to the serious loss of photoelectrons striking at the input electrode of traditional microchannel plate (MCP), photoelectron collection efficiency (CE) of photomultiplier tubes based on MCP (MCP-PMTs) fluctuates around the MCP open area fraction and cannot make a breakthrough. Depositing a thin film of high secondary electron yield material on the MCP is proposed as an effective approach to improve the CE. The available simulation and experimental data to validate it, however, is sparse. In our work, a three-dimensional small area MCP model is developed in CST Studio Suite to evaluate the collection efficiencies of PMTs based on the traditional MCP and the coated one, respectively. Results predict that CE of the PMT based on the coated MCP has a significant increase and a better uniformity, which is expected to reach 100%.

The Effects of Different Nitrogen Sources on Yield and Yield Components of Sweet Corn (Zea mays L. saccharata

Directory of Open Access Journals (Sweden)

ali mojab ghasroddashti

2017-09-01

percent level calculated for mean comparison. Results and Discussion Results indicated that the different sources of nitrogen had significant effect on the number of grains per row and the number of grains per ear as well as ear and canned yield except for the number of ears per m2 and number of row per ear. Mean comparison indicated that the highest ear yield (2178 g.m-2 was obtained in the treatments of 100 kg N + 4 tons of poultry manure (T6 and the lowest yield (1188 g.m-2 in control (T9. Using of organic sources of nitrogen with chemical fertilizer led to increase ear yield. In other words, integrated treatments had better effect on yield than chemical and organic treatments. In addition, the highest canned harvest index (42.8 ton.ha-1 and ear harvest index (48.7 ton.ha-1 was related to 100 kg net nitrogen + 12 ton municipal solid waste compost (T8 treatments. Municipal solid waste compost and poultry manure in the 100 and 150 kg nitrogen levels caused to increase of canned harvest index and ear harvest index. This matter is indicative more effect of municipal solid waste compost than poultry manure on two indices.Generally, the combined use of organic manures and chemical fertilizers could be an appropriate method to increase sweet corn yield and soil fertility. According to the obtained results, T6 treatment can be recommended. Conclusion Based on the obtained results, it seems that single application of organic fertilizers cannot lead to maximum yield, therefore, to obtain the optimal yield integrated application of organic and chemical fertilizers (T6 can be recommended for farmers in the region.

Electronic processes in organic electronics bridging nanostructure, electronic states and device properties

CERN Document Server

Kudo, Kazuhiro; Nakayama, Takashi; Ueno, Nobuo

2015-01-01

The book covers a variety of studies of organic semiconductors, from fundamental electronic states to device applications, including theoretical studies. Furthermore, innovative experimental techniques, e.g., ultrahigh sensitivity photoelectron spectroscopy, photoelectron yield spectroscopy, spin-resolved scanning tunneling microscopy (STM), and a material processing method with optical-vortex and polarization-vortex lasers, are introduced. As this book is intended to serve as a textbook for a graduate level course or as reference material for researchers in organic electronics and nanoscience from electronic states, fundamental science that is necessary to understand the research is described. It does not duplicate the books already written on organic electronics, but focuses mainly on electronic properties that arise from the nature of organic semiconductors (molecular solids). The new experimental methods introduced in this book are applicable to various materials (e.g., metals, inorganic and organic mater...

Comparison of Four Weighting Methods in Fuzzy-based Land Suitability to Predict Wheat Yield

Directory of Open Access Journals (Sweden)

Fatemeh Rahmati

2017-06-01

climatic conditions like mean, maximum and minimum air temperatures during growing period as well as edaphologic properties like EC, pH, ESP, percent of clay, silt, sand, gravel, gypsum and CaCO3 content. Climatic data collected from the Shahrekord synoptic station were used to assess climatic land suitability for wheat. Qualitative land suitability evaluation was carried out using the fuzzy approach. Potential yield was calculated using the method proposed by FAO. Using MATLAB software, qualitative and quantitative land evaluation were classified based on fuzzy logic approach. In fuzzy method, climatic factors are used to achieve climatic index. Clay and sand percent were applied to calculate soil texture. To determine the membership degrees,bell membership functions were used. Parameters of function shapes were transformed to equations with variable coefficients and the best coefficients were eventually chosen based on the model determination coefficient. In evaluation method based on fuzzy logic, the weights are used for land characteristics. In fuzzy logic method, weights were calculated by four methods. These methods consist of neural network using 1 neuron and 4 neurons, multivariate and Partial Least Squares (PLS regressions. Comparison of the coefficient of determination results of multivariate regression and RMSE is carried out between observed and predicted yield. Weight calculations were conducted by using MINITAB software to PLS and multivariate regression. Also, Neurosolution 5 was used for weight calculation based on neural network. Results and Discussion: The calculated weights were differed by using the four applied methods. In all methods, the maximum weight was related to gravel, and minimum weight was related to clay. The results of land index and predicted yield calculation were different in some points (3, 6, 7, 13, 14, 19, and 21 for four methods. The coefficient of determination of calculated weights were 0.595, 0.56, 0.6 and 0.56 for neural network

Auroral electron energies

International Nuclear Information System (INIS)

McEwan, D.J.; Duncan, C.N.; Montalbetti, R.

1981-01-01

Auroral electron characteristic energies determined from ground-based photometer measurements of the ratio of 5577 A OI and 4278 A N 2 + emissions are compared with electron energies measured during two rocket flights into pulsating aurora. Electron spectra with Maxwellian energy distributions were observed in both flights with an increase in characteristic energy during each pulsation. During the first flight on February 15, 1980 values of E 0 ranging from 1.4 keV at pulsation minima to 1.8 keV at pulsation maxima were inferred from the 5577/4278 ratios, in good agreement with rocket measurements. During the second flight on February 23, direct electron energy measurements yielded E 0 values of 1.8 keV rising to 2.1 keV at pulsation maxima. The photometric ratio measurements in this case gave inferred E 0 values about 0.5 keV lower. This apparent discrepancy is considered due to cloud cover which impaired the absolute emission intensity measurements. It is concluded that the 5577/4278 ratio does yield a meaningful measure of the characteristic energy of incoming electrons. This ratio technique, when added to the more sensitive 6300/4278 ratio technique usable in stable auroras can now provide more complete monitoring of electron influx characteristics. (auth)

Modified Sternglass theory for the emission of secondary electrons by fast-electron impact

International Nuclear Information System (INIS)

Suszcynsky, D.M.; Borovsky, J.E.

1992-01-01

The Sternglass theory [Sternglass, Phys. Rev. 108, 1 (1957)] for fast-ion-induced secondary-electron emission from metals has been modified to predict the secondary-electron yield from metals impacted by energetic (several keV to about 200 keV) electrons. The primary modification of the theory accounts for the contribution of the backscattered electrons to the production of secondary electrons based on a knowledge of the backscattered-electron energy distribution. The modified theory is in reasonable agreement with recent experimental data from gold targets in the 6--30-keV electron energy range

Comparison of Interfacial Electron Transfer Efficiency in [Fe(ctpy)2]2+-TiO2 and [Fe(cCNC)2]2+-TiO2 Assemblies: Importance of Conformational Sampling.

Science.gov (United States)

Mukherjee, Sriparna; Liu, Chang; Jakubikova, Elena

2018-02-22

Fe(II)-polypyridines have limited applications as chromophores in dye-sensitized solar cells due to the short lifetimes (∼100 fs) of their photoactive metal-to-ligand charge transfer (MLCT) states formed upon photoexcitation. Recently, a 100-fold increase in the MLCT lifetime was observed in a [Fe(CNC) 2 ] 2+ complex (CNC = 2,6-bis(3-methylimidazole-1-ylidine)pyridine) which has strong σ-donating N-heterocyclic carbene ligand in comparison to the weaker field parent [Fe(tpy) 2 ] 2+ complex (tpy = 2,2':6',2″-terpyridine). This study utilizes density functional theory (DFT), time-dependent DFT, and quantum dynamics simulations to investigate the interfacial electron transfer (IET) in [Fe(cCNC) 2 ] 2+ (cCNC = 4'-carboxy-2,6-bis(3-methylimidazole-1-ylidine)pyridine) and [Fe(ctpy) 2 ] 2+ (ctpy = 4'-carboxy-2,2':6',2″-terpyridine) sensitized TiO 2 . Our results suggest that the replacement of tpy by CNC ligand does not significantly speed up the IET kinetics in the [Fe(cCNC) 2 ] 2+ -TiO 2 assembly in comparison to the [Fe(ctpy) 2 ] 2+ -TiO 2 analogue. The high IET efficiency in the [Fe(cCNC) 2 ] 2+ -TiO 2 assemblies is therefore due to longer lifetime of [Fe(cCNC) 2 ] 2+ photoactive 3 MLCT states rather than faster electron injection kinetics. It was also found that the inclusion of conformational sampling in the computational model is important for proper description of the IET processes in these systems, as the models relying on the use of only fully optimized structures may yield misleading results. The simulations presented in this work also illustrate various pitfalls of utilizing properties such as electronic coupling, number of available acceptor states, and driving force, as well as calculations based on Fermi's golden rule framework, to reach conclusions on the IET efficiency in dye-semiconductor systems.

Dark field electron holography for strain measurement

Energy Technology Data Exchange (ETDEWEB)

Beche, A., E-mail: armand.beche@fei.com [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Rouviere, J.L. [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Barnes, J.P.; Cooper, D. [CEA-LETI, Minatec Campus, F-38054 Grenoble (France)

2011-02-15

Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. -- Research Highlights: {yields} Step by step explanation of the dark field electron holography technique. {yields} Presentation of the theoretical equations to obtain quantitative strain map. {yields} Description of experimental parameters influencing dark field holography results. {yields} Quantitative strain measurement on a SiGe layer embedded in a silicon matrix.

Estimated yield of double-strand breaks from internal exposure to tritium.

Science.gov (United States)

Chen, Jing

2012-08-01

Internal exposure to tritium may result in DNA lesions. Of those, DNA double-strand breaks (DSBs) are believed to be important. However, experimental and computational data of DSBs induction by tritium are very limited. In this study, microdosimetric characteristics of uniformly distributed tritium were determined in dimensions of critical significance in DNA DSBs. Those characteristics were used to identify other particles comparable to tritium in terms of microscopic energy deposition. The yield of DSBs could be strongly dependent on biological systems and cellular environments. After reviewing theoretically predicted and experimentally determined DSB yields available in the literature for low-energy electrons and high-energy protons of comparable microdosimetric characteristics to tritium in the dimensions relevant to DSBs, it is estimated that the average DSB yields of 2.7 × 10(-11), 0.93 × 10(-11), 2.4 × 10(-11) and 1.6 × 10(-11) DSBs Gy(-1) Da(-1) could be reasonable estimates for tritium in plasmid DNAs, yeast cells, Chinese hamster V79 cells and human fibroblasts, respectively. If a biological system is not specified, the DSB yield from tritium exposure can be estimated as (2.3 ± 0.7) × 10(-11) DSBs Gy(-1) Da(-1), which is a simple average over experimentally determined yields of DSBs for low-energy electrons in various biological systems without considerations of variations caused by different techniques used and obvious differences among different biological systems where the DSB yield was measured.

Determination of Psub(K) values to the 172, 103 and 97 keV levels and the fluorescence yield. omega. sub(K) of Eu after electron capture by /sup 153/Gd

Energy Technology Data Exchange (ETDEWEB)

Singh, K; Grewal, B S; Sahota, H S [Punjabi Univ., Patiala (India). Dept. of Physics

1985-03-01

From an analysis of K x-ray-..gamma..-ray sum peaks observed with an intrinsic Ge detector the K-capture probabilities (Psub(K)) to the 172, 103 and 97 keV levels in the decay of /sup 153/Gd have been determined; these yield an electron-capture energy Qsub(EC)=245 +- 2. The K-capture probability to the 172 keV level differs significantly from that found in the literature. With these results the K-shell fluorescence yield of Eu is ..omega..sub(K)=0.935 +- 0.019.

Experimental study of mixing and asymmetry in Z {yields} b anti b

Energy Technology Data Exchange (ETDEWEB)

Zwaan, B.C.C. van der

1995-12-14

The subject of this thesis is the measurement of the mixing in the B{sup 0} anti B{sup 0} system and the forward-backward asymmetry in the electroweak process e{sup +}e{sup -}{yields}Z{yields}b{sup b} anti. These measurements yield a test of the Standard Model. The experiment is performed with data taken by the L{sub 3} detector, one of the four detectors along the LEP electron-positron storage ring at CERN. (orig./HSI).

Measure of the e+e-{yields}bb Cross Section at the LEP Energies; Medida de la seccion eficaz e''+e''-{yields}bb a las Energias de LEP

Energy Technology Data Exchange (ETDEWEB)

Arce Dubois, P.

1992-07-01

In the present work I analyse the data collected during 1990 by the L3 detector, situated in the electron-positron collider LEP. After selecting the events e''+e''-{yields} bb through their semileptonic decays into muons, I calculate the cross section for the process e''+e''- {yields} bb at different energy points around the mass of the vectorial boson Z, and I measure some parameters of the Standard Model, namely, the Br(b{yields}{mu} ),{gamma}{sub z}n-{yields}bb/{gamma}{sub z}n{yields}had and {gamma}{sub z}n{yields}bb{gamma}{sub z}n{yields}e''+e''-. (Author) 26 refs.

Comparison of (alpha, n) thick-target neutron yields and spectra from ORIGEN-S and SOURCES

International Nuclear Information System (INIS)

Brown, T.H.; Wilson, W.B.; Perry, R.T.; Charlton, W.S.

1998-01-01

Both ORIGEN-S and SOURCES generate thick-target neutron yields and energy spectra from (α,n) reactions in homogeneous materials. SOURCES calculates yield and spectra for any material containing α-emitting and (α,n) target elements by simulating reaction physics, using α-emission energy spectra, elemental stopping cross sections, (α,n) cross sections for target nuclei, and branching fractions to produce-nuclide energy levels. This methodology results in accurate yield and spectra. ORIGEN-S has two options for calculating yields and spectra. The UO 2 option (default) estimates yields and spectra assuming the input α-emitters to be infinitely dilute in UO 2 . The borosilicate-glass option estimates yields from the total input material composition and generates spectra purportedly representative of spectra generated by 238 Pu, 241 Am, 242 Cm, and 244 Cm infinitely dilute in borosilicate glass, even if none of these four α-emitters are present in the input material composition. Because yields from the borosilicate-glass option in ORIGEN-S are based on entire input material composition and are reasonably accurate, the same is often assumed to be true for spectra. The input/output functionality of the borosilicate-glass option, along with ambiguity in ORIGEN-S documentation, gives the incorrect impression that spectra representative of input compositions are generated. This impression is reinforced by wide usage of the SCALE code system and its ORIGEN-S module and their sponsorship by the US Nuclear Regulatory Commission

Fusion Yield Enhancement in Magnetized Laser-Driven Implosions

International Nuclear Information System (INIS)

Chang, P. Y.; Fiksel, G.; Hohenberger, M.; Knauer, J. P.; Marshall, F. J.; Betti, R.; Meyerhofer, D. D.; Seguin, F. H.; Petrasso, R. D.

2011-01-01

Enhancement of the ion temperature and fusion yield has been observed in magnetized laser-driven inertial confinement fusion implosions on the OMEGA Laser Facility. A spherical CH target with a 10 atm D 2 gas fill was imploded in a polar-drive configuration. A magnetic field of 80 kG was embedded in the target and was subsequently trapped and compressed by the imploding conductive plasma. As a result of the hot-spot magnetization, the electron radial heat losses were suppressed and the observed ion temperature and neutron yield were enhanced by 15% and 30%, respectively.

Evaluation of Yield, Yield Components and Essential Oil Content of Marigold (Calendula officinalis L. with the Use of Nitrogen and Vermicompost

Directory of Open Access Journals (Sweden)

Alireza Pazoki

2016-10-01

Full Text Available Environmenal problems resulting from application of nitrogen fertilizers in the production plant materials led agricultural specialists to use clean and alternative methods to towards the organic farming and use of organic fertilizers. In this study, thus, the effect of nitrogen and vermicompost fertilizer rates on yield, yield components, essential oil content and some morphological traits of marigold was studied in a split plot experiment based on completely randomized blocks design with 3 replications in Shahr-e-Rey region during 2013 growing season. Nitrogen rates with 3 levels (0, 60, 120 and 180 kg.ha-1 were assigned to main plots and vermicompost with 3 levels (0, 10, and 20 t.ha-1 to the sub plots. Mean comparison of simple effects indicated that the plants treated with 120 kg.ha-1 nitrogen fertilizer and 20 t.ha-1 organic fertilizer vermicompost produced higher trait values under study than control (non application of vermincompost. Interaction effect of experimented factors was significant on all traits under evaluation. Thus, highest seed yield (1567 kg.ha-1, biological yield (6664 kg.ha-1 and essential oil yield (8.85 kg.ha-1 obtained by the application of 120 kg.ha-1 nitrogen fertilizer and 20 t.ha-1 varmicompost. Based on the results obtained it could be said that nitrogen and vermicompost may improve seed and biological yield and yield components of marigold.

Off-axis and inline electron holography: Experimental comparison

International Nuclear Information System (INIS)

Latychevskaia, Tatiana; Formanek, Petr; Koch, C.T.; Lubk, Axel

2010-01-01

Electron holography is a very powerful technique for mapping static electric and magnetic potentials down to atomic resolution. While electron holography is commonly considered synonymous with its off-axis variant in the high energy electron microscopy community, inline electron holography is widely applied in low-energy electron microscopy, where the realization of the off-axis setup is still an experimental challenge. This paper demonstrates that both inline and off-axis holography may be used to recover amplitude and phase shift of the very same object, in our example latex spheres of 90 and 200 nm in diameter, producing very similar results, provided the object does not charge under the electron beam.

Low-energy electron-induced dissociation in gas-phase nicotine, pyridine, and methyl-pyrrolidine

Science.gov (United States)

Ryszka, Michal; Alizadeh, Elahe; Li, Zhou; Ptasińska, Sylwia

2017-09-01

Dissociative electron attachment to nicotine, pyridine, and N-methyl-pyrrolidine was studied in the gas phase in order to assess their stability with respect to low-energy electron interactions. Anion yield curves for different products at electron energies ranging from zero to 15 eV were measured, and the molecular fragmentation pathways were proposed. Nicotine does not form a stable parent anion or a dehydrogenated anion, contrary to other biological systems. However, we have observed complex dissociation pathways involving fragmentation at the pyrrolidine side accompanied by isomerization mechanisms. Combining structure optimization and enthalpy calculations, performed with the Gaussian09 package, with the comparison with a deuterium-labeled N-methyl-d3-pyrrolidine allowed for the determination of the fragmentation pathways. In contrast to nicotine and N-methylpyrrolidine, the dominant pathway in dissociative electron attachment to pyridine is the loss of hydrogen, leading to the formation of an [M—H]- anion. The presented results provide important new information about the stability of nicotine and its constituent parts and contribute to a better understanding of the fragmentation mechanisms and their effects on the biological environment.

Dependence of secondary electron emission on the incident angle and the energy of primary electrons bombarding bowl-structured beryllium surfaces

International Nuclear Information System (INIS)

Kawata, Jun; Ohya, Kaoru.

1994-01-01

A Monte Carlo simulation of the secondary electron emission from beryllium is combined with a model of bowl structure for surface roughness, for analyzing the difference between the electron emissions for normal and oblique incidences. At normal incidence, with increasing the roughness parameter H/W, the primary energy E pm at which the maximum electron yield occurs becomes higher, and at more than the E pm , the decrease in the yield is slower; where H and W are the depth and width of the bowl structure, respectively. The dispersion of incident angle to the microscopic surface causes a small increase in the yield at oblique incidence, whereas the blocking of primary electrons from bombarding the bottom of the structure causes an opposite trend. The strong anisotropy in the polar angular distribution with respect to the azimuthal angle is calculated at oblique incidence. (author)

A surface-electrode quadrupole guide for electrons

Energy Technology Data Exchange (ETDEWEB)

Hoffrogge, Johannes Philipp

2012-12-19

This thesis reports on the design and first experimental realization of a surface-electrode quadrupole guide for free electrons. The guide is based on a miniaturized, planar electrode layout and is driven at microwave frequencies. It confines electrons in the near-field of the microwave excitation, where strong electric field gradients can be generated without resorting to resonating structures or exceptionally high drive powers. The use of chip-based electrode geometries allows the realization of versatile, microstructured potentials with the perspective of novel quantum experiments with guided electrons. I present the design, construction and operation of an experiment that demonstrates electron confinement in a planar quadrupole guide for the first time. To this end, electrons with kinetic energies from one to ten electron-volts are guided along a curved electrode geometry. The stability of electron guiding as a function of drive parameters and electron energy has been studied. A comparison with numerical particle tracking simulations yields good qualitative agreement and provides a deeper understanding of the electron dynamics in the guiding potential. Furthermore, this thesis gives a detailed description of the design of the surface-electrode layout. This includes the development of an optimized coupling structure to inject electrons into the guide with minimum transverse excitation. I also discuss the extension of the current setup to longitudinal guide dimensions that are comparable to or larger than the wavelength of the drive signal. This is possible with a modified electrode layout featuring elevated signal conductors. Electron guiding in the field of a planar, microfabricated electrode layout allows the generation of versatile and finely structured guiding potentials. One example would be the realization of junctions that split and recombine a guided electron beam. Furthermore, it should be possible to prepare electrons in low-lying quantum mechanical

A surface-electrode quadrupole guide for electrons

International Nuclear Information System (INIS)

Hoffrogge, Johannes Philipp

2012-01-01

This thesis reports on the design and first experimental realization of a surface-electrode quadrupole guide for free electrons. The guide is based on a miniaturized, planar electrode layout and is driven at microwave frequencies. It confines electrons in the near-field of the microwave excitation, where strong electric field gradients can be generated without resorting to resonating structures or exceptionally high drive powers. The use of chip-based electrode geometries allows the realization of versatile, microstructured potentials with the perspective of novel quantum experiments with guided electrons. I present the design, construction and operation of an experiment that demonstrates electron confinement in a planar quadrupole guide for the first time. To this end, electrons with kinetic energies from one to ten electron-volts are guided along a curved electrode geometry. The stability of electron guiding as a function of drive parameters and electron energy has been studied. A comparison with numerical particle tracking simulations yields good qualitative agreement and provides a deeper understanding of the electron dynamics in the guiding potential. Furthermore, this thesis gives a detailed description of the design of the surface-electrode layout. This includes the development of an optimized coupling structure to inject electrons into the guide with minimum transverse excitation. I also discuss the extension of the current setup to longitudinal guide dimensions that are comparable to or larger than the wavelength of the drive signal. This is possible with a modified electrode layout featuring elevated signal conductors. Electron guiding in the field of a planar, microfabricated electrode layout allows the generation of versatile and finely structured guiding potentials. One example would be the realization of junctions that split and recombine a guided electron beam. Furthermore, it should be possible to prepare electrons in low-lying quantum mechanical

Bio/Nano Electronic Devices and Sensors

National Research Council Canada - National Science Library

Jones, W. K

2008-01-01

...) Cold cathode microwave generator and ceramic electron multiplier-ceramic multiplier using a novel secondary electron yield materials of MgO and CNT was demonstrated as well as cooling structures...

Comparison of mushroom yield for Pleurotus Sajor Caju and Pleurotus Florida in different number of flushes

International Nuclear Information System (INIS)

Rosnani Abdul Rashid; Mat Rasol Awang; Hassan Hamdani Hassan Mutaat; Meswan Maskom

2006-01-01

This paper aimed at comparing the mushroom yield of Pleurotus sajor caju and Pleurotus florida which was harvested in five flushes. The γ-irradiated empty fruit bunch (EFB) at 25kGy was used as cultivation substrate. About 1 to 2% liquid seed of P. sajor caju and P. florida was inoculated into cultivation substrate. After 30 days, the inoculated substrate was opened for fruiting. For both species, the maximum mushroom yield was obtained in first flush and the lowest yield from the fifth flush. This show the mushroom yield is affected by number of flush. From analysis, the mushroom yield of P. florida was much better compared to P. sajor caju for all flushes. (Author)

The Effect of Irrigation Intervals and Arbuscular Mycorrhizal Fungi on Chlorophyll Index, Yield and Yield Components of Grain Sorghum

Directory of Open Access Journals (Sweden)

J. Hamzei

2014-08-01

Full Text Available This experiment was carried out to study the effect of irrigation intervals and arbuscular mycorrhizal fungi on chlorophyll index, yield and yield components of grain sorghum. A factorial experiment was done based on randomized complete block design (RCBD with three replications at the Agriculture Research Station faculty of Agriculture, Bu- Ali Sina University in growing season of 2011. Irrigation intervals (7, 14 and 21 days with three levels of seed inoculation (control without inoculation, inoculation with Glomus mossea and inoculation with G. intraradices were the experimental treatments. Results indicated that the effect of irrigation intervals and mycorrhizal fungi were significant for traits of chlorophyll index, percentage of root symbiosis (PRS, number of grain per panicle, 1000 seed weight, grain yield and harvest index (HI. Maximum value for each trait was observed at G. mossea treatment. G. mossea treatment in comparison with G. intraradices and control treatment can increase the grain yield of sorghum up to 6.80 and 23.10%, respectively. Also, with increasing irrigation interval from 7 to 21 days, PRS increased up to 27.9%. Maximum value for grain yield (755 g m-2 was achieved at irrigation every 14 days and application of G. mossea treatment. But, there was no significant difference between irrigation sorghum plants every 14 days and application of G. mossea and irrigation every 7 days and application of either G. mossea or G. intraradices. In general, irrigation of sorghum plants every 14 days and supplying of G. mossea can produce the highest grain yield, while decreasing water consumption for sorghum production.

Study of CP violation in the channel B{sub d}{sup 0} {yields} J/{psi}(ee)K{sub S}{sup 0}, identification and reconstruction of electrons in the LHCb experiment; Etude de la violation de CP dans le canal B{sub d}{sup 0} {yields} J/{psi}(ee)K{sub S}{sup 0}, identification et reconstruction des electrons dans l'experience LHCb

Energy Technology Data Exchange (ETDEWEB)

Terrier, H

2005-04-15

LHCb experiment has been designed in order to do precise measurements of CP violation and rare decays with B mesons. In 2000, the collaboration decided to modify the spectrometer in order to minimize the amount of matter seen by particles and to optimize the trigger. This thesis was done in this context and is divided into 3 parts. The first part is relative to the electron identification and to the recovery of Bremsstrahlung photons emitted by electrons when they pass through matter. Electron identification is mainly based on information provided by calorimeter system but also uses RICH and muon system. A method based on reference histograms had been developed which combine information provided by these detectors. Electron identification efficiency, for electrons in ECAL acceptance is 95% and the pion mis-identification rates 0.8% with a 65% purity of electron sample. Bremsstrahlung recovery allows the selection of J/{phi} decaying in e{sup +}e{sup -} pair and of B{sub d}{sup 0} {yields} J/{phi}(ee)K{sub S}{sup 0} channel which are described in the second part. The selection of this channel was developed in order to get an acceptable selection efficiency with a good rejection of background. A set of kinematic and topological cuts were designed and total selection efficiency is 0.176%, corresponding to 28000 untagged events reconstructed by year, with a ratio B/S belonging to [0.017;0.069] (at 90% of confidence level) for inclusive bb-bar background. In the third part, B meson flavour tagging is presented. The addition of information provided by the vertex locator allows to reject electron coming from conversion and to improve slightly the performances. The LHCb sensibility to sin(2{beta}) from B{sup 0} {yields} J/{psi}K{sub S}{sup 0} decay is also determined. The statistical error, expected after one year of data collecting, corresponding to an integrated luminosity of 2 fb{sup -1} and bb-bar pair cross section of 0.5 mb, varies from 0.015 to 0.020 according to

Electron-impact-induced K plus M shell ionization in solid targets of medium-Z elements studied by means of high-resolution x-ray spectroscopy

International Nuclear Information System (INIS)

Ludziejewski, T.; Rymuza, P.; Sujkowski, Z.; Borchert, G.; Dousse, J.; Rheme, C.; Polasik, M.

1996-01-01

The Kβ 2 x-ray spectra of zirconium, niobium, molybdenum, and palladium bombarded by 150 and 300 keV electrons were measured with a high-resolution transmission curved crystal spectrometer. Multiconfiguration Dirac-Fock calculations were used for the decomposition of the experimental spectra into the Kβ 2 M 0 (diagram) and Kβ 2 M 1 (satellite) components. The probabilities of energy dependent (direct Coulomb and two-step) processes were estimated from the differences in the satellite line yields for electrons and photons. The satellite yields are found to be considerably enhanced in comparison with those for the proton-induced ionization recently measured and analyzed in the same way [T. Ludziejewski et al., Phys. Rev. A 52, 2791 (1995)]. This result indicates the importance of multielectron effects in the K plus M shell ionization by energetic projectiles. copyright 1996 The American Physical Society

Evaluation of Yield, Yield Components and Growth Indices of Safflower (Carthamus tinctorius L. in Conventional and Organic Farming Systems

Directory of Open Access Journals (Sweden)

Mahdieh Hajghani

2017-09-01

with conventional farming, inorganic fertilization was considered as a conventional agriculture (CA for each replication. Growth indices were assessed based on the growing degree days (GDD. After harvested, the head number per plant, seed number per head, 1000 seed weight and seed yield were evaluated. Also, two separate statistical analyses were used for comparison organic treatments with each other and conventional agriculture with organic treatments. Results and discussion The results showed that the maximum LAI, TDW and CGR have been determined at 9 t ha-1 vermicompost and 3000 ppm humic acid in CA. Likewise, the results indicated that vermicompost leads to a significant increase in seed yield, flower yield and yield components except 1000 seed weight. Head number per plant, seed number per head and seed yield were affected by humic acid treatments and increased significantly from 1000 to 3000 ppm. However, 1000 seed weight decreased with the increasing concentration of humic acid. It should be mentioned that, 9 t ha-1 vermicompost and 3000 ppm humic acid produced the highest head number per plant (24.75, seed number per head (56.71 and seed yield (4268.17 kg ha-1 in two years that in comparison with CA were increased 79.22%, 30.37% and 89.49%, respectively. Conclusion The results of this study indicated that acceptable yield was obtained with increasing HA concentration at lower levels of vermicompost compared to the higher amount of vermicompost without HA that is economically beneficial. For example, application of 6 t ha-1 vermicompost + 3000 ppm HA had higher seed yield (3027.08 kg ha-1 than 9 t ha-1 vermicompost without foliar application of HA (2722.5 kg ha-1, although there was no significant difference between them.

Lactation yield: Interval level comparison of milk records for genetic ...

African Journals Online (AJOL)

Milk recording intervals was studied by analysing 1220 lactation records of Friesian x Arsi crossbred cows kept in south eastern highlands of Ethiopia. Milk Recording Intervals (MRI) comparison was made at 15, 30 and 45 day's length. Accuracy was measured in terms of percentage difference between actual and estimated ...

X-ray induced production and yield kinetics of photo- and Auger Electrons in semiconductors

International Nuclear Information System (INIS)

Peregudov, V.I.; Pashaev, Eh.M.

1991-01-01

The paper is dedicated to theoretical and experimental analysis of the mechanism of indirect excitation of soft Auger-electrons due to atom electron ionization using Ge crystal exposed to MoK α radiation as an example. Process of generation of these Auger-electrons is considered in detail, solution of kinetic equation for electrons, as well as, experimental data proving crucial role of indirect processes in generation of soft Auger-electrons are given

Rice yield estimation with multi-temporal Radarsat-2 data

Science.gov (United States)

Chen, Chi-Farn; Son, Nguyen-Thanh; Chen, Cheng-Ru

2015-04-01

Rice is the most important food crop in Taiwan. Monitoring rice crop yield is thus crucial for agronomic planners to formulate successful strategies to address national food security and rice grain export issues. However, there is a real challenge for this monitoring purpose because the size of rice fields in Taiwan was generally small and fragmented, and the cropping calendar was also different from region to region. Thus, satellite-based estimation of rice crop yield requires the data that have sufficient spatial and temporal resolutions. This study aimed to develop models to estimate rice crop yield from multi-temporal Radarsat-2 data (5 m resolution). Data processing were carried out for the first rice cropping season from February to July in 2014 in the western part of Taiwan, consisting of four main steps: (1) constructing time-series backscattering coefficient data, (2) spatiotemporal noise filtering of the time-series data, (3) establishment of crop yield models using the time-series backscattering coefficients and in-situ measured yield data, and (4) model validation using field data and government's yield statistics. The results indicated that backscattering behavior varied from region to region due to changes in cultural practices and cropping calendars. The highest correlation coefficient (R2 > 0.8) was obtained at the ripening period. The robustness of the established models was evaluated by comparisons between the estimated yields and in-situ measured yield data showed satisfactory results, with the root mean squared error (RMSE) smaller than 10%. Such results were reaffirmed by the correlation analysis between the estimated yields and government's rice yield statistics (R2 > 0.8). This study demonstrates advantages of using multi-temporal Radarsat-2 backscattering data for estimating rice crop yields in Taiwan prior to the harvesting period, and thus the methods were proposed for rice yield monitoring in other regions.

Assessing the role of secondary electron emission on the characteristics of 6-cavity magnetrons with transparent cathode through particle-in-cell simulations

Energy Technology Data Exchange (ETDEWEB)

Qiu, Hao; Joshi, Ravi P., E-mail: rjoshi@odu.edu [Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529-0246 (United States); Prasad, Sarita; Schamiloglu, Edl [Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87131-0001 (United States); Ludeking, Lars [ATK Mission Systems, 8560 Cinderbed Road, Suite 700, Newington, Virginia 22122 (United States)

2014-05-21

Effects of secondary electron emission (SEE) on the performance of a 6-cavity relativistic magnetron with transparent cathodes are probed through particle-in-cell simulations. Appropriate relations for the secondary electron yield have been developed and used. For comparisons, separate simulations have been performed with- and without electron cascading. Simulation results seem to indicate SEE to be detrimental to the power output due to deviations in the starting trajectories of secondary electrons, and the reduced fraction with synchronized rotational velocity. A higher reduction in output power is predicted with electron cascading, though mode competition was not seen at the 0.65 T field. A possible solution to mitigating SEE in magnetrons for high power microwave applications would be to alter the surface properties of emitting electrodes through irradiation, which can lead to graphitic film formation.

Estimated yield of double-strand breaks from internal exposure to tritium

Energy Technology Data Exchange (ETDEWEB)

Chen, Jing [Health Canada, Radiation Protection Bureau, Ottawa, ON (Canada)

2012-08-15

Internal exposure to tritium may result in DNA lesions. Of those, DNA double-strand breaks (DSBs) are believed to be important. However, experimental and computational data of DSBs induction by tritium are very limited. In this study, microdosimetric characteristics of uniformly distributed tritium were determined in dimensions of critical significance in DNA DSBs. Those characteristics were used to identify other particles comparable to tritium in terms of microscopic energy deposition. The yield of DSBs could be strongly dependent on biological systems and cellular environments. After reviewing theoretically predicted and experimentally determined DSB yields available in the literature for low-energy electrons and high-energy protons of comparable microdosimetric characteristics to tritium in the dimensions relevant to DSBs, it is estimated that the average DSB yields of 2.7 x 10{sup -11}, 0.93 x 10{sup -11}, 2.4 x 10{sup -11} and 1.6 x 10{sup -11} DSBs Gy{sup -1} Da{sup -1} could be reasonable estimates for tritium in plasmid DNAs, yeast cells, Chinese hamster V79 cells and human fibroblasts, respectively. If a biological system is not specified, the DSB yield from tritium exposure can be estimated as (2.3 ± 0.7) x 10{sup -11} DSBs Gy{sup -1} Da{sup -1}, which is a simple average over experimentally determined yields of DSBs for low-energy electrons in various biological systems without considerations of variations caused by different techniques used and obvious differences among different biological systems where the DSB yield was measured. (orig.)

Evaluation of the Effect of Different Irrigation Levels of Drip Irrigation (Tape on Yield and Yield Components of Corn

Directory of Open Access Journals (Sweden)

mohammad karimi

2016-02-01

irrigation water in drip tape systems in one and two rows planting patterns with different plant densities. The experiment was conducted on randomized complete blocks as a split plot (Split block design with 3 replicates in the Qazvin region. Four levels of irrigation including: 80, 100 and 120 percent of water requirement with drip irrigation (tape and 100% water requirement with furrow irrigation (control treatment as main plots and method of planting (one and two rows with three levels of crop density including: 75000, 90000 and 105000 as subplots were considered. After harvesting, grain yield, number of rows per ear, number of kernels per ear row, number of grains per ear and 1000-kernel weigh were measured. Results and Discussion: The results of simple variance analysis of attributes showed that the method of planting has a significant difference on the level of 5% for grain yield, but on the other the measured attributes did not have any significant effect. The respective effect of planting method and crop density showed a significant difference on the level of 5% for grain yield, number of kernels per ear and the 1000-grain weight, whereas it did not have any significant effect on the other measured attributes. The respective effects of irrigation method, planting method and crop density showed a significant difference on the level of 1% for the attributes of the number of kernels per ear. The planting in one row resulted in significantly higher grain yields than the other planting patterns. In mean comparisons of the interactions between irrigation methods, crop density and planting method, grain yield in drip irrigation at a level of 120% water requirement in the two rows planting pattern and crop density equal to 75000 plants was shown in the lead on the level of 10%. The results showed that the yields of the treatments were only affected by the method of planting and planting of one row lead the planting of two rows. According to means comparison and water use

Refinement of Monte Carlo simulations of electron-specimen interaction in low-voltage SEM

International Nuclear Information System (INIS)

Kieft, Erik; Bosch, Eric

2008-01-01

A Monte Carlo tool is presented for the simulation of secondary electron (SE) emission in a scanning electron microscope (SEM). The tool is based on the Geant4 platform of CERN. The modularity of this platform makes it comparatively easy to add and test individual physical models. Our aim has been to develop a flexible and generally applicable tool, while at the same time including a good description of low-energy (<50 eV) interactions of electrons with matter. To this end we have combined Mott cross-sections with phonon-scattering based cross-sections for the elastic scattering of electrons, and we have adopted a dielectric function theory approach for inelastic scattering and generation of SEs. A detailed model of the electromagnetic fields from an actual SEM column has been included in the tool for ray tracing of secondary and backscattered electrons. Our models have been validated against experimental results through comparison of the simulation results with experimental yields, SE spectra and SEM images. It is demonstrated that the resulting simulation package is capable of quantitatively predicting experimental SEM images and is an important tool in building a deeper understanding of SEM imaging.

Measurement of the intensity ratio of Auger and conversion electrons for the electron capture decay of 125I

Science.gov (United States)

Alotiby, M.; Greguric, I.; Kibédi, T.; Lee, B. Q.; Roberts, M.; Stuchbery, A. E.; Tee, Pi; Tornyi, T.; Vos, M.

2018-03-01

Auger electrons emitted after nuclear decay have potential application in targeted cancer therapy. For this purpose it is important to know the Auger electron yield per nuclear decay. In this work we describe a measurement of the ratio of the number of conversion electrons (emitted as part of the nuclear decay process) to the number of Auger electrons (emitted as part of the atomic relaxation process after the nuclear decay) for the case of 125I. Results are compared with Monte-Carlo type simulations of the relaxation cascade using the BrIccEmis code. Our results indicate that for 125I the calculations based on rates from the Evaluated Atomic Data Library underestimate the K Auger yields by 20%.

Measurement of the intensity ratio of Auger and conversion electrons for the electron capture decay of 125I.

Science.gov (United States)

Alotiby, M; Greguric, I; Kibédi, T; Lee, B Q; Roberts, M; Stuchbery, A E; Tee, Pi; Tornyi, T; Vos, M

2018-03-21

Auger electrons emitted after nuclear decay have potential application in targeted cancer therapy. For this purpose it is important to know the Auger electron yield per nuclear decay. In this work we describe a measurement of the ratio of the number of conversion electrons (emitted as part of the nuclear decay process) to the number of Auger electrons (emitted as part of the atomic relaxation process after the nuclear decay) for the case of 125 I. Results are compared with Monte-Carlo type simulations of the relaxation cascade using the BrIccEmis code. Our results indicate that for 125 I the calculations based on rates from the Evaluated Atomic Data Library underestimate the K Auger yields by 20%.

Defining adolescent common mental disorders using electronic primary care data: a comparison with outcomes measured using the CIS-R.

Science.gov (United States)

Cornish, Rosie P; John, Ann; Boyd, Andy; Tilling, Kate; Macleod, John

2016-12-01

To compare the prevalence of common mental disorders (CMDs) derived from data held in primary care records with that measured using the revised Clinical Interview Schedule (CIS-R) in order to assess the potential robustness of findings based only on routinely collected data. Comparison study using linkage between the Avon Longitudinal Study of Parents and Children (ALSPAC) and electronic primary care records. We studied 1562 adolescents who had completed the CIS-R in ALSPAC at age 17-18 years and had linkage established to their primary care records. Outcome measures from ALSPAC were whether or not an individual met International Classification of Diseases-10 criteria for a diagnosis of (1) a CMD or, specifically, (2) depression. Lists of Read codes corresponding to diagnoses, symptoms and treatments were used to create 12 definitions of CMD and depression alone using the primary care data. We calculated sensitivities and specificities of these, using CIS-R definitions as the reference standard. Sensitivities ranged from 5.2% to 24.3% for depression and from 3.8% to 19.2% for CMD. The specificities of all definitions were above 98% for depression and above 96% for CMD.For both outcomes, the definition that included current diagnosis, treatment or symptoms identified the highest proportion of CIS-R cases. Most individuals meeting case definitions for CMD based on primary care data also met CIS-R case definitions. Conversely many individuals identified as cases using the CIS-R had no evidence of CMD in their clinical records. This suggests that clinical databases are likely to yield underestimates of the burden of CMD in the population. However, clinical records appear to yield valid diagnoses which may be useful for studying risk factors and consequences of CMD. The greatest epidemiological value may be obtained when information is available from survey and clinical records. Published by the BMJ Publishing Group Limited. For permission to use (where not already

Electrons scattered inside small dust grains of various materials

International Nuclear Information System (INIS)

Richterova, Ivana; Beranek, Martin; Pavlu, Jiri; Nemecek, Zdenek; Safrankova, Jana

2010-01-01

The dust grain charge in an electron beam is given by a difference in numbers of electrons that fall onto the grain and those leaving it. Electrons with energies exceeding 1 keV can penetrate through submicron-sized dust grains. If the grain is small enough, a yield of these electrons reaches unity but they leave a part of their energy inside the grain and this energy excites secondary electrons. The paper presents a hybrid Monte Carlo code that simulates paths of the primary electrons inside a spherical grain and provides the yield of scattered electrons and their energy spectrum as a function of the grain size and material. This code is based on the Richterovaet al. [Phys. Rev. B 74, 235430 (2006)] model but it includes several corrections important for light materials like carbon or ice. The model was verified using experimental results obtained on large planar samples. For spherical samples, we have found that the yield of scattered electrons reaches unity for 50 nm Au grains illuminated by 5 keV electrons, whereas the same effect can be observed on ≅1000 nm carbon grains.

The Effect of Drought Stress on Morphological Characteristics and Yield Components of Medicinal Plant Fenugreek

Directory of Open Access Journals (Sweden)

N. Bazzazi

2013-06-01

Full Text Available Fenugreek (Trigonella foenum-graecum L. is one of the oldest medicinal plants. In order to study water-stress effects on some morphological characteristics of fenugreek, an experiment was carried out in a strip plots based on randomized complete blocks design with three replicates, at Research Farm of Shahrekord University, Shahrekord, Iran, in 2010. The first factor was allocated to four water stress levels (irrigation after depletion of 20 (as control, 40, 60 and 80% of available soil moisture and the second factor was six fenugreek landraces (Shiraz, Ardestan, Tirancheh, Yazd, Jahrom and Hindi. The results of ANOVA and comparison of means indicated that the effect of water stress was significant for all traits and variation was observed among landraces for all the studied characteristics. Mean comparison showed that drought stress reduced days to flowering, days to maturity, plant height and yield components (number of pods per plant, number of seeds per pod and 1000-kernel weight. It was also revealed that water stress caused reduction in biological yield (43% and grain yield (42.3% of all genotypes. Comparison between landraces indicated that maximum biological and grain yield belonged to Ardestan landrace. Assessment of cluster analysis showed that it was possible to classify Ardestan, Shiraz and Tirancheh as a single group having tolerance to water stress. In general, based on obtained results, the Ardestan landrace, with 22.37 g/plant, had the highest biological yield and Hindi landrace, with 73.83 days to maturity, was the most early-maturing one.

A new set of parameters for 5 Gaussian fission yields systematics

International Nuclear Information System (INIS)

Katakura, Jun-ichi

2003-01-01

A new set of parameters for 5 Gaussian-type fission yields systematics has been proposed for applying to high energy neutron or proton fission and to various kinds of fissioning systems including minor actinides. The mass yields calculated using the systematics were compared with various kinds of measured data including the fission with incident energy higher than 100 MeV and the fission of minor actinide nuclides. The comparisons showed rather good agreement between the calculated values and measured ones for various kinds of fissioning systems. (author)

Electron beams in radiation therapy

International Nuclear Information System (INIS)

Bruinvis, I.A.D.

1987-01-01

Clinical electron beams in interaction with beam flattening and collimating devices are studied, in order to obtain the means for adequate electron therapy. A treatment planning method for arbitrary field shapes is developed that takes the properties of the collimated electron beams into account. An electron multiple-scattering model is extended to incorporate a model for the loss of electrons with depth, in order to improve electron beam dose planning. A study of ionisation measurements in two different phantom materials yields correction factors for electron beam dosimetry. (Auth.)

Effect of high-energy electron irradiation of chicken meat on thiobarbituric acid values, shear values, odor, and cooked yield

International Nuclear Information System (INIS)

Heath, J.L.; Owens, S.L.; Tesch, S.; Hannah, K.W.

1990-01-01

Experiments were conducted to determine whether electron-beam irradiation would affect shear values, yield, odor, and thiobarbituric acid (TBA) values of chicken tissues. Broiler breasts (pectoralis superficialis) and whole thighs were irradiated with an electron-beam accelerator at levels to produce adsorbed doses of 100, 200, and 300 krads on the surface of the sample. The thigh samples were stored for 2, 4, and 8 days before testing for TBA values. The depth to which the radiation had penetrated the pectoralis superficialis muscle was also determined. Radiation penetrated 22 mm into slices of pectoralis superficialis muscle when 100 krad was absorbed by the surface of the tissue. The dose absorbed beneath the tissue surface to a depth of 10 mm was larger than the dose absorbed at the surface. The absorbed dose decreased as the depth of penetration increased. For cooked breast tissue, the shear values and moisture content were not affected by the absorbed radiation. Cooking losses of aged breast tissue were not affected by irradiation, but cooking losses were reduced in breast tissue that had not been aged. Irradiating uncooked thigh and uncooked breast samples produced a characteristic odor that remained after the thighs were cooked but was not detectable after the breast samples were cooked. With two exceptions, no significantly different TBA values were found that could be attributed to irradiation

Analysis of secondary electron emission for conducting materials using 4-grid LEED/AES optics

International Nuclear Information System (INIS)

Patino, M I; Wirz, R E; Raitses, Y; Koel, B E

2015-01-01

A facility utilizing 4-grid optics for LEED/AES (low energy electron diffraction/Auger electron spectroscopy) was developed to measure the total secondary electron yield and secondary electron energy distribution function for conducting materials. The facility and experimental procedure were validated with measurements of 50–500 eV primary electrons impacting graphite. The total yield was calculated from measurements of the secondary electron current (i) from the sample and (ii) from the collection assembly, by biasing each surface. Secondary electron yield results from both methods agreed well with each other and were within the spread of previous results for the total yield from graphite. Additionally, measurements of the energy distribution function of secondary electrons from graphite are provided for a wider range of incident electron energies. These results can be used in modeling plasma-wall interactions in plasmas bounded by graphite walls, such as are found in plasma thrusters, and divertors and limiters of magnetic fusion devices. (paper)

Reduction in clover-grass yield caused by different traffic intensities

DEFF Research Database (Denmark)

Green, Ole; Jørgensen, Rasmus Nyholm; Kristensen, Kristian

Different traffic intensities have been shown to have a negative influence on the yield of grass and clover. A full scale grass-clover field trial was established to estimate the effect on clover-grass yields as a function of different wheel loads and tire pressures. The trial comprised 16...... close to the north, south and east border of the field. No significant interactions were found between the timing of crop and soil damage as affected by wheel load and tire pressure. However, at specific times, there was a significant effect of wheel load and secondary by the tire pressure. At all...... measurement times, the yield was lower using a wheel load of 4745 kg than for a wheel load of 2865 kg.     Key words (for Electronic Reference Library) Traffic intensities, tire load/pressure, clover/grass, yield loss, ...

Development of high yielding mutants in lentil

International Nuclear Information System (INIS)

Rajput, M.A.; Sarwar, G.; Siddiqui, K.A.

2001-01-01

Full text: Lentil (Lens culinaris Medik.) locally known as Masoor, is the second most important rabi pulse crop, after chickpea, in Pakistan. It is cultivated on an area of over 63,400 ha, which constitutes about 4.83% of the total area under pulses. The annual production of the crop is 28,200 tones with an average yield of 445 kg/ha. Yield at the national level is very low, about one-half of the world's yield, which is mainly due to non-availability of high yield potential genotypes. Keeping in view the importance of mutants in developing a large number of new varieties, an induced mutations programme was initiated at AEARC, Tandojam during 1987-88, to develop high yielding varieties in lentil. For this, seeds of two lentil varieties, 'Masoor-85' and 'ICARDA-8' had been irradiated with gamma-rays ranging from 100-600 Gy in NIAB, Faisalabad during 1990. Selections were made in M2 on the basis of earliness, plant height, branches/plant and 100 grain weight. After confirming these mutants in M3 they were promoted in station yield trials and studied continuously for three consecutive years (1993- 1995). Overall results revealed that these mutants have consistent improvement of earliness in flowering and maturity. Plant height also increased in all mutant lines except AEL 23/40/91 where reduction in this attribute was observed as compared to parent variety. Mutant lines AEL 49/20/91 and AEL 13/30/91 showed improvement in 100 grain weight. The improvement of some agronomic characters enhanced the yield of mutant lines in comparison to parent varieties (Masoor-85 and ICARDA-8). The diversity in yield over the respective parents was computed from 6.94 to 60.12%. From these encouraging results it is hoped that mutant lines like AEL 12/30/91 and AEL 49/20/91 may serve as potential lentil genotypes in future. (author)

Brazilian Soybean Yields and Yield Gaps Vary with Farm Size

Science.gov (United States)

Jeffries, G. R.; Cohn, A.; Griffin, T. S.; Bragança, A.

2017-12-01

Understanding the farm size-specific characteristics of crop yields and yield gaps may help to improve yields by enabling better targeting of technical assistance and agricultural development programs. Linking remote sensing-based yield estimates with property boundaries provides a novel view of the relationship between farm size and yield structure (yield magnitude, gaps, and stability over time). A growing literature documents variations in yield gaps, but largely ignores the role of farm size as a factor shaping yield structure. Research on the inverse farm size-productivity relationship (IR) theory - that small farms are more productive than large ones all else equal - has documented that yield magnitude may vary by farm size, but has not considered other yield structure characteristics. We examined farm size - yield structure relationships for soybeans in Brazil for years 2001-2015. Using out-of-sample soybean yield predictions from a statistical model, we documented 1) gaps between the 95th percentile of attained yields and mean yields within counties and individual fields, and 2) yield stability defined as the standard deviation of time-detrended yields at given locations. We found a direct relationship between soy yields and farm size at the national level, while the strength and the sign of the relationship varied by region. Soybean yield gaps were found to be inversely related to farm size metrics, even when yields were only compared to farms of similar size. The relationship between farm size and yield stability was nonlinear, with mid-sized farms having the most stable yields. The work suggests that farm size is an important factor in understanding yield structure and that opportunities for improving soy yields in Brazil are greatest among smaller farms.

COMPARISON OF THREE MODELS TO PREDICT ANNUAL SEDIMENT YIELD IN CARONI RIVER BASIN, VENEZUELA

Directory of Open Access Journals (Sweden)

Edilberto Guevara-Pérez

2007-01-01

Full Text Available Caroní River Basin is located in the south-eastern part of Venezuela; with an area of 92.000 km2, 40% of which belongs to the main affluent, the Paragua River. Caroní basin is the source of 66% of energy of the country. About 85% of the hydro electrical energy is generated in Guri reservoir located in the lower part of the watershed. To take provisions to avoid the reservoir silting it is very important the study of sediment yield of the basin. In this paper result of three empirical sediment yield models: Langbein- Schumm, Universal Soil Loss Equation-USLE and Poesen, are compared with observed data from five sub basins with records of twenty to thirty years. Men values of sediment yield for low, middle and upper Caroní are of 27, 76, 17 t/km2-year, respectively; and 46 and 78 t/km2-year for low and upper Paragua sub basins are. Standard errors of estimates vary between 13 and 29 for Langbein-Schumm model; between 8 and 32 for USLE procedure; and between 9 and 79, for Poesen model. Sediment yield predictions by Langbein-Schumm model seem to the best in Caroní basin.

Alkylation of isobutane with light olefins: Yields of alkylates for different olefins

Energy Technology Data Exchange (ETDEWEB)

Albright, L.F. [Purdue Univ., West Lafayette, IN (United States); Kranz, K.E.; Masters, K.R. [STRATCO, Inc., Leawood, KS (United States)

1993-12-01

For alkylation of isobutane with C{sub 3}-C{sub 5} olefins using sulfuric acid as the catalyst, the yields of alkylates with different olefins are compared as the operating conditions are changed. The results of recent pilot plant experiments with propylene, C{sub 4} olefins, and C{sub 5} olefins permit such comparisons. The yields expressed as weight of alkylate produced per 100 wt of olefin consumed varied from about 201:100 to 220:100. Weight ratios of the isobutane consumed per olefin consumed vary from about 101:100 to 120:100. differences of yield values are explained by the changes in the overall chemistry. The procedure employed to calculate yields with good accuracy is based on the analysis of the alkylate and the amount of conjunct polymers produced. Based on literature data, yields are also reported for alkylations using HF as the catalyst.

Partial ion yield and NEXAFS of 2-(perfluorooctyl)ethanethiol self-assembled monolayer: Comparison with PTFE results

CERN Document Server

Setoyama, H; Murase, T; Imamura, M; Mase, K; Okudaira, K K; Hara, M; Ueno, N

2003-01-01

Partial-ion-yield (PIY) spectra using ion time-of-flight (TOF) method and near-edge absorption fine structure (NEXAFS) spectra were measured for 2-(perfluorooctyl)ethanethiol [CF sub 3 (CF sub 2) sub 7 (CH sub 2) sub 2 SH] self-assembled monolayer (F8-SAM) on Au(1 1 1) near carbon K-edge. The PIY spectra of the F8-SAM at the magic angle, where -CF sub 3 groups exist at the surface were compared with those of the rubbed polytetrafluoroethylene (PTFE) thin film. The F sup + intensity from the F8-SAM at the photon energy of the sharp peak of the NEXAFS, which originates from the excitation of C1s electron to sigma sup * (C-F) states at -CF sub 2 - chain, was extremely smaller than that from the rubbed PTFE film. This result clearly indicates that the ions observed by PIY do not originate from the film inside but from the surface. This was confirmed by changes in ion-TOF mass spectra during soft X-ray induced etching of the F8-SAM. The NEXAFS peaks of the F8-SAM were also assigned by considering PIY results.

Compilation and evaluation of fission yield nuclear data. Final report of a co-ordinated research project 1991-1996

International Nuclear Information System (INIS)

2000-12-01

tables and are therefore enclosed as a CD-ROM, which also includes a computer program for calculating fission yields. The CD-ROM contains products of the CRP work comprising additional valuable information, namely the computer program YCALC for downloading directly to a PC, and appendices with tables which were considered too bulky for inclusion in the printed book. The YCALC program (G. Grommes, H.O. Kling, H.O. Denschlag) is a PC version of Wahl's programs for calculating chain, cumulative or independent yields for 12 fission reactions as described in Sections 4.1 and 4.2. Both programs give the same results, but YCALC is more convenient for PC users. Appendix A presents some tables of evaluated fission yields as provided by evaluators. One task of the CRP was the inter-comparison of evaluated fission yield files with the goal to reveal discrepancies among evaluations as well as among experimental data and to identify (ranges of) fission yields that need to be measured. In the course of the CRP, several such studies were undertaken, and the results are presented in Appendix B. Appendix A includes tables of evaluated fission yields (Fission product yields for U235T, U238F, U238H and Pu239T (A.C. Wahl)), a tabulation of fission product yield values and percent errors that have been derived from Wahl's evaluation of fractional independent yields. The chain yields from the ENDF/B-VI file (T.R. England and B.F. Rider) are included with 60 sets of chain yields derived from the ENDF/B-V1 evaluated yield file. Appendix B includes inter-comparison of evaluated fission yield files. Inter-comparison of evaluated fission yield files was one of the CRP tasks. Several intercomparisons have been made which are all included on the CD-ROM: Comparison of chain yields for 11 fission reactions (A.C. Wahl); Comparison of ENDFIB- VI and UKFY3 with experimental results; Comparison of ENDF/B-VI and JEF-2.2 fission yield libraries for U235T, U238F, Pu239T and Pu239F (F. Storrer and D. Rochman

Multiple electron generation in a sea of electronic states

Science.gov (United States)

Witzel, Wayne; Shabaev, Andrew; Efros, Alexander; Hellberg, Carl; Verne, Jacobs

2009-03-01

In traditional bulk semiconductor photovoltaics (PVs), each photon may excite a single electron-hole, wasting excess energy beyond the band-gap as heat. In nanocrystals, multiple excitons can be generated from a single photon, enhancing the PV current. Multiple electron generation (MEG) may result from Coulombic interactions of the confined electrons. Previous investigations have been based on incomplete or over-simplified electronic-state representations. We present results of quantum simulations that include hundreds of thousands of configuration states and show how the complex dynamics, even in a closed electronic system, yields a saturated MEG effect on a femtosecond timescale. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

The Effect of Different Fertilizer Management on Yield and Yield Components of Black Seed (Nigella sativa L.

Directory of Open Access Journals (Sweden)

P rezvani moghaddam

2017-08-01

, manure + nitroxin + mycorrhizae, manure + biosulfur and control. Plots were designed with 4 m long and 2 m width (8 m2, 0.5 m apart each other. Seed sowing was done at 18th March on both sides of the furrows. Final plant density was determined equal to 200 plants m-2. At maturity stage, number of branch per plant, number of follicle per plant, seed weight per follicle and 1000- seed weight were determined based on randomly selection of eight plant. Moreover, grain and biological yields as well as harvest index of black seed were measured by considering the side effects. For statistical analysis, Duncan multiple range test (p≤0.05 was used to separate the experimental means using SAS 9.1 software. Results and discussion According to the results, effects of urea and cow manure treatments on grain and biological yields of black seed were significant. However, cow manure, in comparison with urea fertilizer, had more significant effects in increasing mentioned traits of black seed. For instance, cow manure treatment increased grain yield by 25%, compared with urea treatment. Generally, advantages of manure in comparison with chemical fertilizer can be related to the slow and more balanced release of nutrient contents as well as improving the physical and chemical soil characteristics over growing season. On the other hand, the results showed that biological fertilizers had no effects in increasing grain and biological yields of black seed, except biosulfur treatment. From the results, there was a positive correlation between 1000- seed weight with grain yield. Moreover, similar correlations were found between number of branch per plant and grain yield, number of follicle per plant and grain yield as well as seed weight per follicle and grain yield. Nonetheless, relationship between harvest index and grain yield was determined as a negative correlation. These results are in agreement with those of Moradi et al. (2010 who found a significant decrease in harvest index of

Backward ejected electrons from collisions of 1 MeV/u Oq+ projectiles with argon gas

International Nuclear Information System (INIS)

Berryman, J.W.; Breinig, M.; Segner, F.; Desai, D.

1993-01-01

We will be presenting results from a series of experiments measuring the yields and energy distributions of electrons emitted at 1800 with respect to the 1 MeV/u O q+ [q=3-8] ion beam. We have systematically studied the yield per incident ion and the energy distribution of electrons as a function of the incident projectile charge state. The energy distributions show two prominent structures: a narrow peak due to target LMM Auger electrons and a broad hump due to projectile binary-encounter electrons. The shapes and yields of the Auger electron peaks are nearly independent of the incident charge state. The shapes and yields of the binary-encounter electron peaks are sensitive functions of the number of projectile electrons carried into the collision. A well defined binary-encounter electron peak appears only for charge states q=3, 4, and 5

Absolute Negative Resistance Induced by Directional Electron-Electron Scattering in a Two-Dimensional Electron Gas

Science.gov (United States)

Kaya, Ismet I.; Eberl, Karl

2007-05-01

A three-terminal device formed by two electrostatic barriers crossing an asymmetrically patterned two-dimensional electron gas displays an unusual potential depression at the middle contact, yielding absolute negative resistance. The device displays momentum and current transfer ratios that far exceed unity. The observed reversal of the current or potential in the middle terminal can be interpreted as the analog of Bernoulli’s effect in a Fermi liquid. The results are explained by directional scattering of electrons in two dimensions.

Secondary electron emission from lithium and lithium compounds

Energy Technology Data Exchange (ETDEWEB)

Capece, A. M., E-mail: capecea@tcnj.edu [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Department of Physics, The College of New Jersey, Ewing, New Jersey 08628 (United States); Patino, M. I.; Raitses, Y. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Koel, B. E. [Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08540 (United States)

2016-07-04

In this work, measurements of electron-induced secondary electron emission (SEE) yields of lithium as a function of composition are presented. The results are particularly relevant for magnetic fusion devices such as tokamaks, field-reversed configurations, and stellarators that consider Li as a plasma-facing material for improved plasma confinement. SEE can reduce the sheath potential at the wall and cool electrons at the plasma edge, resulting in large power losses. These effects become significant as the SEE coefficient, γ{sub e}, approaches one, making it imperative to maintain a low yield surface. This work demonstrates that the yield from Li strongly depends on chemical composition and substantially increases after exposure to oxygen and water vapor. The total yield was measured using a retarding field analyzer in ultrahigh vacuum for primary electron energies of 20–600 eV. The effect of Li composition was determined by introducing controlled amounts of O{sub 2} and H{sub 2}O vapor while monitoring film composition with Auger electron spectroscopy and temperature programmed desorption. The results show that the energy at which γ{sub e} = 1 decreases with oxygen content and is 145 eV for a Li film that is 17% oxidized and drops to less than 25 eV for a fully oxidized film. This work has important implications for laboratory plasmas operating under realistic vacuum conditions in which oxidation significantly alters the electron emission properties of Li walls.

Secondary electron emission from lithium and lithium compounds

International Nuclear Information System (INIS)

Capece, A. M.; Patino, M. I.; Raitses, Y.; Koel, B. E.

2016-01-01

In this work, measurements of electron-induced secondary electron emission (SEE) yields of lithium as a function of composition are presented. The results are particularly relevant for magnetic fusion devices such as tokamaks, field-reversed configurations, and stellarators that consider Li as a plasma-facing material for improved plasma confinement. SEE can reduce the sheath potential at the wall and cool electrons at the plasma edge, resulting in large power losses. These effects become significant as the SEE coefficient, γ e , approaches one, making it imperative to maintain a low yield surface. This work demonstrates that the yield from Li strongly depends on chemical composition and substantially increases after exposure to oxygen and water vapor. The total yield was measured using a retarding field analyzer in ultrahigh vacuum for primary electron energies of 20–600 eV. The effect of Li composition was determined by introducing controlled amounts of O 2 and H 2 O vapor while monitoring film composition with Auger electron spectroscopy and temperature programmed desorption. The results show that the energy at which γ e  = 1 decreases with oxygen content and is 145 eV for a Li film that is 17% oxidized and drops to less than 25 eV for a fully oxidized film. This work has important implications for laboratory plasmas operating under realistic vacuum conditions in which oxidation significantly alters the electron emission properties of Li walls.

A dual-phase xenon TPC for scintillation and ionisation yield measurements in liquid xenon

Science.gov (United States)

Baudis, Laura; Biondi, Yanina; Capelli, Chiara; Galloway, Michelle; Kazama, Shingo; Kish, Alexander; Pakarha, Payam; Piastra, Francesco; Wulf, Julien

2018-05-01

A small-scale, two-phase (liquid/gas) xenon time projection chamber ( Xurich II) was designed, constructed and is under operation at the University of Zürich. Its main purpose is to investigate the microphysics of particle interactions in liquid xenon at energies below 50 keV, which are relevant for rare event searches using xenon as target material. Here we describe in detail the detector, its associated infrastructure, and the signal identification algorithm developed for processing and analysing the data. We present the first characterisation of the new instrument with calibration data from an internal ^83{m} Kr source. The zero-field light yield is 15.0 and 14.0 photoelectrons/keV at 9.4 and 32.1 keV, respectively, and the corresponding values at an electron drift field of 1 kV/cm are 10.8 and 7.9 photoelectrons/keV. The charge yields at these energies are 28 and 31 electrons/keV, with the proportional scintillation yield of 24 photoelectrons per one electron extracted into the gas phase, and an electron lifetime of 200 μ s. The relative energy resolution, σ /E, is 11.9 and 5.8% at 9.4 and 32.1 keV, respectively using a linear combination of the scintillation and ionisation signals. We conclude with measurements of the electron drift velocity at various electric fields, and compare these to literature values.

SU-D-19A-07: Dosimetric Comparison of HDR Plesiotherapy and Electron Beam Therapy for Superficial Lesions

Energy Technology Data Exchange (ETDEWEB)

Mitchell, A; Jacob, D; Andreou, K; Raben, A; Chen, H; Koprowski, C; Mourtada, F [Christiana Care Hospital, Newark, DE (United States)

2014-06-01

Purpose: Large superficial (skin, soft tissue sarcoma) lesions located on curved areas are hard to treat with electrons. The Freiburg Flap (Nucletron, Netherlands) is a flexible mesh style surface which can be easily shaped to fit curved surfaces for reproducible HDR fraction delivery. To understand the fundamental dosimetric differences, a dosimetric comparison was made between HDR plesiotherapy (Freiburg applicator for lesions over 4cm) and external electron beam radiotherapy over cases with varying target curvature (both stylized and clinical cases). Methods: Four stylized cases with variable complexity were created using artificial DICOM axial CT slices and RT structures (a square and three curved structures on a 4.5cm radius cylinder). They were planned using Oncentra v4.3 and exported to Pinnacle v9.6 for electrons planning. The HDR source dwell positions were optimized for the best coverage of the targets using graphical optimization. Electron treatment plans were created in Pinnacle using the same CT and RT structures of three HDR cases with surface lesions previously treated with the Freiburg flap. The En face electron plans used 6-12 MeV electrons and 0.5–1 cm bolus was added to increase surface dose. The electron plans were prescribed to an isodose line to conform to the target. Results: For all lesions, the average target dose coverage was similar (D90ave of 100% for HDR vs 101% for electrons). For lesions with high curvature, the HDR coverage was better (D90 102% vs D90 97% for electron). For all cases, adjacent structures high dose region was lower for HDR than electrons (D1cc 100% for HDR vs D1cc 111% for electrons). Conclusion: HDR plesiotherapy offers excellent target conformity for superficial targets similar to electrons. However, for lesions with complex curved surfaces, HDR has the advantage to achieve better dose distributions using graphical optimization to spare adjacent normal tissue while maximizing target coverage.

Recent Experimental Results on Amorphous Carbon Coatings for Electron Cloud Mitigation

CERN Document Server

Yin Vallgren, C; Chiggiato, P; Costa Pinto, P; Neupert, H; Taborelli, M; Rumolo, G; Shaposhnikova, E; Vollenberg, W

2011-01-01

Amorphous carbon (a-C) thin films, produced in different coating configurations by using DC magnetron sputtering, have been investigated in laboratory for low secondary electron yield (SEY) applications. After the coatings had shown a reliable low initial SEY, the a-C thin films have been applied in the CERN Super Proton Synchrotron (SPS) and tested with Large Hadron Collider (LHC) type beams.Currently, we have used a-C thin film coated in so-called liner configuration for the electron cloud monitors. In addition the vacuum chambers of three dipole magnets have been coated and inserted into the machine. After describing the different configurations used for the coatings, results of the tests in the machine and a summary of the analyses after extraction will be presented. Based on comparison between different coating configurations, a new series of coatings has been applied on three further dipole magnet vacuum chambers. They have been installed and will be tested in coming machine development runs.

Consequences of diverse use of nitrogen sources on grain yield ...

African Journals Online (AJOL)

Muhammad Waseem

2012-08-28

Aug 28, 2012 ... sources on grain yield, grain quality and growth attributes of hybrid maize (Zea mays L.) at the. Agronomic Research Area, University ...... rate were found in 2009. Evans et al. (2003) also noted similar interactive effects of hybrid and N sources in maize. In year 2008, contrasts comparison (Table 4) between ...

Higher biomolecules yield in phytoplankton under copper exposure.

Science.gov (United States)

Silva, Jaqueline Carmo; Echeveste, Pedro; Lombardi, Ana Teresa

2018-05-30

Copper is an important metal for industry, and its toxic threshold in natural ecosystems has increased since the industrial revolution. As an essential nutrient, it is required in minute amounts, being toxic in slightly increased concentrations, causing great biochemical transformation in microalgae. This study aimed at investigating the physiology of Scenedesmus quadricauda, a cosmopolitan species, exposed to copper concentrations including those that trigger intracellular biochemical modifications. The Cu exposure concentrations tested ranged from 0.1 to 25 µM, thus including environmentally important levels. Microalgae cultures were kept under controlled environmental conditions and monitored daily for cell density, in vivo chlorophyll a, and photosynthetic quantum yield (Φ M ). After 24 h growth, free Cu 2+ ions were determined, and after 96 h, cellular Cu concentration, total carbohydrates, proteins, lipids, and cell volume were determined. The results showed that both free Cu 2+ ions and cellular Cu increased with Cu increase in culture medium. Microalgae cell abundance and in vivo chlorophyll a were mostly affected at 2.5 µM Cu exposure (3.8 pg Cu cell -1 ) and above. Approximately 31% decrease of photosynthetic quantum yield was obtained at the highest Cu exposure concentration (25 µM; 25 pg Cu cell -1 ) in comparison with the control. However, at environmentally relevant copper concentrations (0.5 µM Cu; 0.4 pg Cu cell -1 ) cell volume increased in comparison with the control. Considering biomolecules accumulation per unit cell volume, the highest carbohydrates and proteins yield was obtained at 1.0 µM Cu (1.1 pg Cu cell -1 ), while for lipids higher Cu was necessary (2.5 µM Cu; 3.8 pg Cu cell -1 ). This study is a contribution to the understanding of the effects of environmentally significant copper concentrations in the physiology of S. quadricauda, as well as to biotechnological approach to increase biomolecule yield in

Trading carbon for food: global comparison of carbon stocks vs. crop yields on agricultural land.

Science.gov (United States)

West, Paul C; Gibbs, Holly K; Monfreda, Chad; Wagner, John; Barford, Carol C; Carpenter, Stephen R; Foley, Jonathan A

2010-11-16

Expanding croplands to meet the needs of a growing population, changing diets, and biofuel production comes at the cost of reduced carbon stocks in natural vegetation and soils. Here, we present a spatially explicit global analysis of tradeoffs between carbon stocks and current crop yields. The difference among regions is striking. For example, for each unit of land cleared, the tropics lose nearly two times as much carbon (∼120 tons·ha(-1) vs. ∼63 tons·ha(-1)) and produce less than one-half the annual crop yield compared with temperate regions (1.71 tons·ha(-1)·y(-1) vs. 3.84 tons·ha(-1)·y(-1)). Therefore, newly cleared land in the tropics releases nearly 3 tons of carbon for every 1 ton of annual crop yield compared with a similar area cleared in the temperate zone. By factoring crop yield into the analysis, we specify the tradeoff between carbon stocks and crops for all areas where crops are currently grown and thereby, substantially enhance the spatial resolution relative to previous regional estimates. Particularly in the tropics, emphasis should be placed on increasing yields on existing croplands rather than clearing new lands. Our high-resolution approach can be used to determine the net effect of local land use decisions.

Electron Bifurcation: Thermodynamics and Kinetics of Two-Electron Brokering in Biological Redox Chemistry

Energy Technology Data Exchange (ETDEWEB)

Zhang, Peng; Yuly, Jonathon L.; Lubner, Carolyn E. [National Renewable Energy Laboratory, Golden, Colorado 80401, United States; Mulder, David W. [National Renewable Energy Laboratory, Golden, Colorado 80401, United States; King, Paul W. [National Renewable Energy Laboratory, Golden, Colorado 80401, United States; Peters, John W. [Institute; Beratan, David N. [Department

2017-08-23

How can proteins drive two electrons from a redox active donor onto two acceptors at very different potentials and distances? And how can this transaction be conducted without dissipating very much energy or violating the laws of thermodynamics? Nature appears to have addressed these challenges by coupling thermodynamically uphill and downhill electron transfer reactions, using two-electron donor cofactors that have very different potentials for the removal of the first and second electron. Although electron bifurcation is carried out with near perfection from the standpoint of energy conservation and electron delivery yields, it is a biological energy transduction paradigm that has only come into focus recently. This Account provides an exegesis of the biophysical principles that underpin electron bifurcation.

Genetic basis of some yield components in gossypium hirsutum l

International Nuclear Information System (INIS)

Javed, A.; Azhar, F.M.; Khan, I.A.; Rana, S.A.

2014-01-01

A 5 * 5 diallel analysis was conducted to study the inheritance of seed cotton yield, number of bolls and boll weight in Gossypium hirsutum L. using combining ability technique. The analysis of the data revealed that variance due to specific combining ability was significant for all the three traits signifying the importance of non additive gene action. The comparison of the parents showed that NF-801-2-37 was the best general combiner for seed cotton yield, number of bolls and boll weight followed by Acala-63-75. Best hybrid combinations identified were Acala-63-75 * NF-801-2-37 for seed cotton yield and DPL-61 * NF-801-2-37 for number of bolls and boll weight. Higher proportion of dominance variance in all three traits suggested delayed selection or use of heterosis breeding in crop improvement programs. (author)

A numerical integration-based yield estimation method for integrated circuits

International Nuclear Information System (INIS)

Liang Tao; Jia Xinzhang

2011-01-01

A novel integration-based yield estimation method is developed for yield optimization of integrated circuits. This method tries to integrate the joint probability density function on the acceptability region directly. To achieve this goal, the simulated performance data of unknown distribution should be converted to follow a multivariate normal distribution by using Box-Cox transformation (BCT). In order to reduce the estimation variances of the model parameters of the density function, orthogonal array-based modified Latin hypercube sampling (OA-MLHS) is presented to generate samples in the disturbance space during simulations. The principle of variance reduction of model parameters estimation through OA-MLHS together with BCT is also discussed. Two yield estimation examples, a fourth-order OTA-C filter and a three-dimensional (3D) quadratic function are used for comparison of our method with Monte Carlo based methods including Latin hypercube sampling and importance sampling under several combinations of sample sizes and yield values. Extensive simulations show that our method is superior to other methods with respect to accuracy and efficiency under all of the given cases. Therefore, our method is more suitable for parametric yield optimization. (semiconductor integrated circuits)

A numerical integration-based yield estimation method for integrated circuits

Energy Technology Data Exchange (ETDEWEB)

Liang Tao; Jia Xinzhang, E-mail: tliang@yahoo.cn [Key Laboratory of Ministry of Education for Wide Bandgap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China)

2011-04-15

A novel integration-based yield estimation method is developed for yield optimization of integrated circuits. This method tries to integrate the joint probability density function on the acceptability region directly. To achieve this goal, the simulated performance data of unknown distribution should be converted to follow a multivariate normal distribution by using Box-Cox transformation (BCT). In order to reduce the estimation variances of the model parameters of the density function, orthogonal array-based modified Latin hypercube sampling (OA-MLHS) is presented to generate samples in the disturbance space during simulations. The principle of variance reduction of model parameters estimation through OA-MLHS together with BCT is also discussed. Two yield estimation examples, a fourth-order OTA-C filter and a three-dimensional (3D) quadratic function are used for comparison of our method with Monte Carlo based methods including Latin hypercube sampling and importance sampling under several combinations of sample sizes and yield values. Extensive simulations show that our method is superior to other methods with respect to accuracy and efficiency under all of the given cases. Therefore, our method is more suitable for parametric yield optimization. (semiconductor integrated circuits)

Influence of non-LTE radiation ablation on imploding neutron yield

International Nuclear Information System (INIS)

Sheng Jiatian; Li Yunsheng; Gao Yaomin; Li Meng; Feng Tinggui; Zhang Lifa; Zeng Xiancai; Mou Wenyong; Feng Jie; Chen Jiabin

2005-01-01

The process of radiative ablation and neutron yields of DD-capsule with CH shell implosion driven by Plank spectrum and nonequilibrium spectrum radiation fields was numerically studied using 1-D RDMG code of multigroup-nonequilibrium radiation hydrodynamics. The simulation results were compared with the experimental results. The results of the simulation show that the nonequilibrium of energy spectrum distribution of the hohlraum radiation source, especially the M-band of it, will preheat DD in the capsule obviously, decrease the compressing ratio, electron and ion temperatures of DD gas, and therefore decrease the neutron yields markedly. The simulation results also show that the law of decreasing of neutron yields with increasing of the CH-sell thickness is in agreement with the experiment basically. (authors)

Revisiting the total ion yield x-ray absorption spectra of liquid water microjets

International Nuclear Information System (INIS)

Saykally, Richard J; Cappa, Chris D.; Smith, Jared D.; Wilson, Kevin R.; Saykally, Richard J.

2008-01-01

Measurements of the total ion yield (TIY) x-ray absorption spectrum (XAS) of liquid water by Wilson et al. (2002 J. Phys.: Condens. Matter 14 L221 and 2001 J. Phys. Chem. B 105 3346) have been revisited in light of new experimental and theoretical efforts by our group. Previously, the TIY spectrum was interpreted as a distinct measure of the electronic structure of the liquid water surface. However, our new results indicate that the previously obtained spectrum may have suffered from as yet unidentified experimental artifacts. Although computational results indicate that the liquid water surface should exhibit a TIY-XAS that is fundamentally distinguishable from the bulk liquid XAS, the new experimental results suggest that the observable TIY-XAS is actually nearly identical in appearance to the total electron yield (TEY-)XAS, which is a bulk probe. This surprising similarity between the observed TIY-XAS and TEY-XAS likely results from large contributions from x-ray induced electron stimulated desorption of ions, and does not necessarily indicate that the electronic structure of the bulk liquid and liquid surface are identical

Sputtering yield calculation for binary target

International Nuclear Information System (INIS)

Jimenez-Rodriguez, J.J.; Rodriguez-Vidal, M.; Valles-Abarca, J.A.

1979-01-01

The generalization for binary targets, of the ideas proposed by Sigmund for monoatomic targets, leads to a set of coupled intergrodifferential equations for the sputtering functions. After moment decomposition, the final formulae are obtained by the standard method based on the Laplace Transform, where the inverse transform is made with the aid of asymptotic expansions in the limit of very high projectile energy as compared to the surface binding energy. The possible loss of stoichiometry for binary targets is analyzed. Comparison of computed values of sputtering yield for normal incidence, with experimental results shows good agreement. (author)

Dose modeling of noninvasive image-guided breast brachytherapy in comparison to electron beam boost and three-dimensional conformal accelerated partial breast irradiation.

Science.gov (United States)

Sioshansi, Shirin; Rivard, Mark J; Hiatt, Jessica R; Hurley, Amanda A; Lee, Yoojin; Wazer, David E

2011-06-01

To perform dose modeling of a noninvasive image-guided breast brachytherapy (NIIGBB) for comparison to electrons and 3DCRT. The novel technology used in this study is a mammography-based, noninvasive breast brachytherapy system whereby the treatment applicators are centered on the planning target volume (PTV) to direct (192)Ir emissions along orthogonal axes. To date, three-dimensional dose modeling of NIIGBB has not been possible because of the limitations of conventional treatment planning systems (TPS) to model variable tissue deformation associated with breast compression. In this study, the TPS was adapted such that the NIIGBB dose distributions were modeled as a virtual point source. This dose calculation technique was applied to CT data from 8 patients imaged with the breast compressed between parallel plates in the cranial-caudal and medial-lateral axes. A dose-volume comparison was performed to simulated electron boost and 3DCRT APBI. The NIIGBB PTV was significantly reduced as compared with both electrons and 3DCRT. Electron boost plans had a lower D(min) than the NIIGBB technique but higher V(100), D(90), and D(50). With regard to PTV coverage for APBI, the only significant differences were minimally higher D(90), D(100), V(80), and V(90), with 3DCRT and D(max) with NIIGBB. The NIIGBB technique, as compared with electrons and 3D-CRT, achieved a lower maximum dose to skin (60% and 10%, respectively) and chest wall/lung (70-90%). NIIGBB achieves a PTV that is smaller than electron beam and 3DCRT techniques. This results in significant normal tissue sparing while maintaining dosimetric benchmarks to the target tissue. Copyright © 2011 Elsevier Inc. All rights reserved.

Electron-Poor Thiophene 1,1-Dioxides: Synthesis, Characterization, and Application as Electron Relays in Photocatalytic Hydrogen Generation.

Science.gov (United States)

Tsai, Chia-Hua; Chirdon, Danielle N; Kagalwala, Husain N; Maurer, Andrew B; Kaur, Aman; Pintauer, Tomislav; Bernhard, Stefan; Noonan, Kevin J T

2015-08-03

The synthesis and characterization of electron-poor thiophene 1,1-dioxides bearing cyanated phenyl groups are reported. The electron-accepting nature of these compounds was evaluated by cyclic voltammetry, and highly reversible and facile reductions were observed for several derivatives. Moreover, some of the reduced thiophene dioxides form colorful anions, which were investigated spectroelectrochemically. Photoluminescence spectra of the electron-deficient sulfones were measured in CH2 Cl2, and they emit in the blue-green region with significant variation in the quantum yield depending on the aryl substituents. By expanding the degree of substitution on the phenyl rings, quantum yields up to 34 % were obtained. X-ray diffraction data are reported for two of the thiophene 1,1-dioxides, and the electronic structure was probed for all synthesized derivatives through DFT calculations. The dioxides were also examined as electron relays in a photocatalytic water reduction reaction, and they showed potential to boost the efficiency. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Measurements of sputtering yields for low-energy plasma ions

International Nuclear Information System (INIS)

Nishi, M.; Yamada, M.; Suckewer, S.; Rosengaus, E.

1979-04-01

Sputtering yields of various wall/limiter materials of fusion devices have been extensively measured in the relevant plasma environment for low-energy light ions (E 14 cm -3 and electron temperature up to 10eV. Target materials used were C (graphite), Ti, Mo, Ta, W, and Fe (stainless steel). In order to study the dependence of the sputtering yields on the incident energy of ions, the target samples were held at negative bias voltage up to 300V. The sputtering yields were determined by a weight-loss method and by spectral line intensity measurements. The data obtained in the present experiment agree well with those previously obtained at the higher energies (E greater than or equal to 200eV) by other authors using different schemes; the present data also extend to substantially lower energies (E approx. > 30eV) than hitherto

Comparison of the effect of liquid humic fertilizers on yield of maize ...

African Journals Online (AJOL)

PC

2012-03-13

Mar 13, 2012 ... humic substances can be useful for living creatures in developing organisms (as ... as catalysts of biochemical reactions; and in antioxidant ... group of heterogeneous organic materials which occur .... application of humic acid led to increased phosphorus ... Humic acid leads to increased plant yield through.

Secondary Electron Emission Materials for Transmission Dynodes in Novel Photomultipliers: A Review

Directory of Open Access Journals (Sweden)

Shu Xia Tao

2016-12-01

Full Text Available Secondary electron emission materials are reviewed with the aim of providing guidelines for the future development of novel transmission dynodes. Materials with reflection secondary electron yield higher than three and transmission secondary electron yield higher than one are tabulated for easy reference. Generations of transmission dynodes are listed in the order of the invention time with a special focus on the most recent atomic-layer-deposition synthesized transmission dynodes. Based on the knowledge gained from the survey of secondary election emission materials with high secondary electron yield, an outlook of possible improvements upon the state-of-the-art transmission dynodes is provided.

Fission yields data generation and benchmarks of decay heat estimation of a nuclear fuel

Science.gov (United States)

Gil, Choong-Sup; Kim, Do Heon; Yoo, Jae Kwon; Lee, Jounghwa

2017-09-01

Fission yields data with the ENDF-6 format of 235U, 239Pu, and several actinides dependent on incident neutron energies have been generated using the GEF code. In addition, fission yields data libraries of ORIGEN-S, -ARP modules in the SCALE code, have been generated with the new data. The decay heats by ORIGEN-S using the new fission yields data have been calculated and compared with the measured data for validation in this study. The fission yields data ORIGEN-S libraries based on ENDF/B-VII.1, JEFF-3.1.1, and JENDL/FPY-2011 have also been generated, and decay heats were calculated using the ORIGEN-S libraries for analyses and comparisons.

Fully stripped heavy ion yield vs energy for Xe and Au ions

International Nuclear Information System (INIS)

Thieberger, P.; Wegner, H.E.; Alonzo, J.; Gould, H.; Anholt, R.E.; Meyerhof, W.E.

1985-01-01

The Bevalac is now capable of accelerating U-238 ions to approximately 1 GeV/amu and measurements have shown that fully stripped U-238 ions are produced with good yield at these energies. However, knowing the stripping yields at different energies for U-238 does not allow an accurate prediction for other, lower Z projectiles. Consequently, extensive stripping yield measurements were made for Au-197 and Xe-139 ions. In addition to the stripping measurements from the direct Bevalac beam, pickup measurements were also made with specially prepared bare, one electron, and two electron ions. Since many research groups are considering heavy ion storage rings and/or synchrotrons, the pickup cross section for bare ions is important to estimate beam lifetime in terms of the average machine vacuum. Since the Mylar target provides a pickup probability similar to air, a preliminary analysis of the Xe 54+ and U 92+ data are presented along with predictions for other ions ranging down to Fe 26+ . 11 refs., 3 figs., 1 tab

Fully stripped heavy ion yield vs energy for Xe and Au ions

Energy Technology Data Exchange (ETDEWEB)

Thieberger, P.; Wegner, H.E.; Alonzo, J.; Gould, H.; Anholt, R.E.; Meyerhof, W.E.

1985-01-01

The Bevalac is now capable of accelerating U-238 ions to approximately 1 GeV/amu and measurements have shown that fully stripped U-238 ions are produced with good yield at these energies. However, knowing the stripping yields at different energies for U-238 does not allow an accurate prediction for other, lower Z projectiles. Consequently, extensive stripping yield measurements were made for Au-197 and Xe-139 ions. In addition to the stripping measurements from the direct Bevalac beam, pickup measurements were also made with specially prepared bare, one electron, and two electron ions. Since many research groups are considering heavy ion storage rings and/or synchrotrons, the pickup cross section for bare ions is important to estimate beam lifetime in terms of the average machine vacuum. Since the Mylar target provides a pickup probability similar to air, a preliminary analysis of the Xe/sup 54 +/ and U/sup 92 +/ data are presented along with predictions for other ions ranging down to Fe/sup 26 +/. 11 refs., 3 figs., 1 tab.

NEST: a comprehensive model for scintillation yield in liquid xenon

Energy Technology Data Exchange (ETDEWEB)

Szydagis, M; Barry, N; Mock, J; Stolp, D; Sweany, M; Tripathi, M; Uvarov, S; Walsh, N; Woods, M [University of California, Davis, One Shields Ave., Davis, CA 95616 (United States); Kazkaz, K, E-mail: mmszydagis@ucdavis.edu [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States)

2011-10-15

A comprehensive model for explaining scintillation yield in liquid xenon is introduced. We unify various definitions of work function which abound in the literature and incorporate all available data on electron recoil scintillation yield. This results in a better understanding of electron recoil, and facilitates an improved description of nuclear recoil. An incident gamma energy range of O(1 keV) to O(1 MeV) and electric fields between 0 and O(10 kV/cm) are incorporated into this heuristic model. We show results from a Geant4 implementation, but because the model has a few free parameters, implementation in any simulation package should be simple. We use a quasi-empirical approach with an objective of improving detector calibrations and performance verification. The model will aid in the design and optimization of future detectors. This model is also easy to extend to other noble elements. In this paper we lay the foundation for an exhaustive simulation code which we call NEST (Noble Element Simulation Technique).

NEST: a comprehensive model for scintillation yield in liquid xenon

International Nuclear Information System (INIS)

Szydagis, M; Barry, N; Mock, J; Stolp, D; Sweany, M; Tripathi, M; Uvarov, S; Walsh, N; Woods, M; Kazkaz, K

2011-01-01

A comprehensive model for explaining scintillation yield in liquid xenon is introduced. We unify various definitions of work function which abound in the literature and incorporate all available data on electron recoil scintillation yield. This results in a better understanding of electron recoil, and facilitates an improved description of nuclear recoil. An incident gamma energy range of O(1 keV) to O(1 MeV) and electric fields between 0 and O(10 kV/cm) are incorporated into this heuristic model. We show results from a Geant4 implementation, but because the model has a few free parameters, implementation in any simulation package should be simple. We use a quasi-empirical approach with an objective of improving detector calibrations and performance verification. The model will aid in the design and optimization of future detectors. This model is also easy to extend to other noble elements. In this paper we lay the foundation for an exhaustive simulation code which we call NEST (Noble Element Simulation Technique).

Induced high yielding mutant in green gram (Vigna radiata (L.) Wilczek)

International Nuclear Information System (INIS)

Pulivarthi, H.R.; Mary, T.N.

1987-01-01

Green gram (mungbean) plays a significant role in meeting the protein requirements in India, with its predominantly vegetarian population. Therefore, an attempt was made to induce desirable mutants. Dry seed of cultivar 'Pusa 105' were irradiated with gamma rays ranging from 10 to 50 krad. A high yielding mutant (Hy I) identified in the M 4 generation from 40 krad dose, has shown significant increases in the number of pods/plants, number of branches/plant, and yield/plant. Further work is in progress. Comparison of the mutant HyI with the parent cultivar Pusa 105 is given

Di-lepton yield from the decay of excited 28Si states

International Nuclear Information System (INIS)

Bacelar, J.C.; Buda, A.; Balanda, A.; Krasznahorkay, A.; Ploeg, H. van der; Sujkowski, Z.; Woude, A. van der

1994-01-01

The first dilepton yield measurements from excited nuclear states obtained with a new Positron-Electron Pair Spectroscopic Instrument (PEPSI) are reported. Nuclear states in 28 Si, with an initial excitation energy E * =50 MeV, were populated via the isospin T=0 reaction 4 He+ 24 Mg and the mixed-isospin 3 He+ 25 Mg reaction. In both reactions the dilepton (e + e - ) and photon decay yields were measured concurrently. An excess of counts in the e + e - spectrum, over the converted photon yield, is observed in the energy region above 15 MeV. An analyses is discussed whereby the observed excess counts are assumed to represent the isoscalar E0 strength in excited nuclear states. (orig.)

The isotropic local Wigner-Seitz model: An accurate theoretical model for the quasi-free electron energy in fluids

Science.gov (United States)

Evans, Cherice; Findley, Gary L.

The quasi-free electron energy V0 (ρ) is important in understanding electron transport through a fluid, as well as for modeling electron attachment reactions in fluids. Our group has developed an isotropic local Wigner-Seitz model that allows one to successfully calculate the quasi-free electron energy for a variety of atomic and molecular fluids from low density to the density of the triple point liquid with only a single adjustable parameter. This model, when coupled with the quasi-free electron energy data and the thermodynamic data for the fluids, also can yield optimized intermolecular potential parameters and the zero kinetic energy electron scattering length. In this poster, we give a review of the isotropic local Wigner-Seitz model in comparison to previous theoretical models for the quasi-free electron energy. All measurements were performed at the University of Wisconsin Synchrotron Radiation Center. This work was supported by a Grants from the National Science Foundation (NSF CHE-0956719), the Petroleum Research Fund (45728-B6 and 5-24880), the Louisiana Board of Regents Support Fund (LEQSF(2006-09)-RD-A33), and the Professional Staff Congress City University of New York.

Track models and radiation chemical yields

International Nuclear Information System (INIS)

Chatterjee, A.; Magee, J.L.

1987-01-01

The authors are concerned only with systems in which single track effects dominate and radiation chemical yields are sums of yields for individual tracks. The authors know that the energy deposits of heavy particle tracks are composed of spurs along the particle trajectory (about one-half of the energy) and a more diffuse pattern composed of the tracks of knock-on electrons, called the penumbra (about one-half of the energy). The simplest way to introduce the concept of a unified track model for heavy particles is to consider the special case of the track of a heavy particle with an LET below 0.2-0.3eV/A, which in practice limits us to protons, deuterons, or particles with energy above 100 MeV per nucleon. At these LET values, to a good approximation, spurs formed by the main particle track can be considered to remain isolated throughout the radiation chemical reactions

Microstructural origins of yield-strength changes in AISI 316 during fission or fusion irradiation

International Nuclear Information System (INIS)

Garner, F.A.; Hamilton, M.L.; Panayotou, N.F.; Johnson, G.D.

1981-08-01

The changes in yield strength of AISI 316 irradiated in breeder reactors have been successfully modeled in terms of concurrent changes in microstructural components. Two new insights involving the strength contributions of voids and Frank loops have been incorporated into the hardening models. Both the radiation-induced microstructure and the yield strength exhibit transients which are then followed by saturation at a level dependent on the irradiation temperature. Extrapolation to anticipated fusion behavior based on microstructural comparisons leads to the conclusion that the primary influence of transmutational differences is only to alter the transient behavior and not the saturation level of yield strength

Modern electronic materials

CERN Document Server

Watkins, John B

2013-01-01

Modern Electronic Materials focuses on the development of electronic components. The book first discusses the history of electronic components, including early developments up to 1900, developments up to World War II, post-war developments, and a comparison of present microelectric techniques. The text takes a look at resistive materials. Topics include resistor requirements, basic properties, evaporated film resistors, thick film resistors, and special resistors. The text examines dielectric materials. Considerations include basic properties, evaporated dielectric materials, ceramic dielectri

New Evidence for Efficient Collisionless Heating of Electrons at the Reverse Shock of a Young Supernova Remnant

Science.gov (United States)

Yamaguchi, Hiroya; Eriksen, Kristoffer A.; Badenes, Carles; Hughes, John P.; Brickhouse, Nancy S.; Foster, Adam R.; Patnaude, Daniel J.; Petre, Robert; Slane, Patrick O.; Smith, Randall K.

2013-01-01

Although collisionless shocks are ubiquitous in astrophysics, certain key aspects of them are not well understood. In particular, the process known as collisionless electron heating, whereby electrons are rapidly energized at the shock front, is one of the main open issues in shock physics. Here, we present the first clear evidence for efficient collisionless electron heating at the reverse shock of Tycho's supernova remnant (SNR), revealed by Fe K diagnostics using high-quality X-ray data obtained by the Suzaku satellite. We detect K beta (3p yields 1s) fluorescence emission from low-ionization Fe ejecta excited by energetic thermal electrons at the reverse shock front, which peaks at a smaller radius than Fe K alpha (2p yields 1s) emission dominated by a relatively highly ionized component. Comparisons with our hydrodynamical simulations imply instantaneous electron heating to a temperature 1000 times higher than expected from Coulomb collisions alone. The unique environment of the reverse shock, which is propagating with a high Mach number into rarefied ejecta with a low magnetic field strength, puts strong constraints on the physical mechanism responsible for this heating and favors a cross-shock potential created by charge deflection at the shock front. Our sensitive observation also reveals that the reverse shock radius of this SNR is about 10% smaller than the previous measurement using the Fe K alpha morphology from the Chandra observations. Since strong Fe K beta fluorescence is expected only from low-ionization plasma where Fe ions still have many 3p electrons, this feature is key to diagnosing the plasma state and distribution of the immediate postshock ejecta in a young SNR.

Modeling long-term yield trends of Miscanthusxgiganteus using experimental data from across Europe

DEFF Research Database (Denmark)

Lesur, Claire; Jeuffroy, Marie-Hélène; Makowski, David

2013-01-01

and the ceiling phases and (ii) to determine whether M. giganteus ceiling phase is followed by a decline phase where yields decrease across years. Data were analyzed through comparisons between a set of statistical growth models. The model that best fitted the experimental data included a decline phase....... The decline intensity and the value of several other model parameters, such as the maximum yield reached during the ceiling phase or the duration of the establishment phase, were highly variable. The highest maximum yields were obtained in the experiments located in the southern part of the studied area....... giganteus is known to have an establishment phase during which annual yields increased as a function of crop age, followed by a ceiling phase, the duration of which is unknown. We built a database including 16 European long-term experiments (i) to describe the yield evolution during the establishment...

DILEPTON YIELD FROM THE DECAY OF EXCITED SI-28 STATES

NARCIS (Netherlands)

BACELAR, JC; BUDA, A; BALANDA, A; KRASZNAHORKAY, A; VANDERPLOEG, H; SUJKOWSKI, Z; VANDERWOUDE, A

1994-01-01

The first dilepton yield measurements from excited nuclear states obtained with a new Positron-Electron Pair Spectroscopic Instrument (PEPSI) are reported. Nuclear states in Si-28, with an initial excitation energy E* = 50 MeV, were populated via the isospin T = 0 reaction He-4 + Mg-24 and the

Effect of different phosphorus fertilizer rates on N-uptake, N-efficiency and zea maize yield in irrigated soils

International Nuclear Information System (INIS)

Khalifa, Kh.

1993-01-01

Effect of different rates of P fertilizer on N-uptake, N-efficiency and zea mays (C.V.Lg 11) were studied by use of 15 N technique. The main objectives of this study were to study effect of different level of P on N-utilization and determine the interaction between P and N on zea mays yield, and the efficiency of N-fertilizer during different stages of plant growth. The field experiment was conducted for two years 1985 and 1986. The treatments were 0, 80, 160 Kg N, as urea Co( 15 NH 2 ) 2 and 0, 40, 80, 160 Kg P 2 O 5 as triplsuperphophate. The experiment design was randomized block of four replicates for each treatment. Yield (grain and dry matter), utilization of urea, N-uptake, total N, N-yield, Ndff%, NDF% and A-values were determined. All results indicate that zea mays responds to the addition of nitrogen and the yield increases with the increase of added nitrogen. The highest yield was for N 2 (160 Kg) level during two seasons. Also zea mays responds clearly to phosphorus especially at stages 1 and 2, where dry matter yield increases with the increase of phosphorus rate. The highest yield was for P 3 (160 Kg) rate. While in grain stage the response was for rate P 1 (40 Kg) and P 2 (80 Kg) in comparison with control. However P 1 , rate was dominant over P 2 and P 3 . The effect of P 2 rate on grain yield was very little in comparison with P 1 , while P 3 decreases the grain yield during two seasons in comparison with control. There is an effect of N and P when added both or separately. There is also effect for interaction between them on the yield (grain and dry matter). Generally, from the previous data we can conclude that the rate 160 Kg N/ha and 40 Kg P 2 O 5 /ha were optimum rate for zea mays fertilization in Deir-Ezzor (Syria) and similar areas for grain yield. (author). 17 refs., 6 tabs

High yield and facile microwave-assisted synthesis of conductive H_2SO_4 doped polyanilines

International Nuclear Information System (INIS)

Gizdavic-Nikolaidis, Marija R.; Jevremovic, Milutin M.; Milenkovic, Maja; Allison, Morgan C.; Stanisavljev, Dragomir R.; Bowmaker, Graham A.; Zujovic, Zoran D.

2016-01-01

The microwave-assisted synthesis of polyaniline (PANI) was performed using ammonium persulphate (APS) as oxidizing agent in 0.5 M–2.5 M concentration range of aqueous sulphuric acid (H_2SO_4) at 93 W applied microwave power of 10 min duration. The microwave (MW) synthesized PANIs had 3 times higher yield in comparison to PANI samples prepared using a classical method, CS (0 W MW power) at the same temperature for 10 min synthesis duration period. Fourier Transform Infrared (FTIR) and UV–Vis spectroscopies confirmed the formation of PANI structure in all products. The influence of H_2SO_4 acid dopant on the spin concentration of MW and CS H_2SO_4 doped PANI samples were examined by EPR spectroscopy, while the morphological characteristics were investigated by using scanning electron microscopy (SEM). XRD results showed amorphous phases in both MW and CS H_2SO_4 doped PANI samples. Conductivity measurements revealed ∼1.5 times higher conductivity values for MW H_2SO_4 doped PANI samples in comparison with PANI samples prepared by the CS method under same condition. The influence of sulfate anion in comparison to chloride anion as a dopant on morphological, dopant levels and conductivity properties of MW PANI samples were also investigated. - Highlights: • Nanoporous microwave synthesized doped polyanilines as chemical sensor material. • Morphology and physical properties of polyanilines depend on acid concentration. • Spin concentration is determined by the nature of the polyaniline synthesis.

Comparison of perimeter trap crop varieties: effects on herbivory, pollination, and yield in butternut squash.

Science.gov (United States)

Adler, L S; Hazzard, R V

2009-02-01

Perimeter trap cropping (PTC) is a method of integrated pest management (IPM) in which the main crop is surrounded with a perimeter trap crop that is more attractive to pests. Blue Hubbard (Cucurbita maxima Duch.) is a highly effective trap crop for butternut squash (C. moschata Duch. ex Poir) attacked by striped cucumber beetles (Acalymma vittatum Fabricius), but its limited marketability may reduce adoption of PTC by growers. Research comparing border crop varieties is necessary to provide options for growers. Furthermore, pollinators are critical for cucurbit yield, and the effect of PTC on pollination to main crops is unknown. We examined the effect of five border treatments on herbivory, pollination, and yield in butternut squash and manipulated herbivory and pollination to compare their importance for main crop yield. Blue Hubbard, buttercup squash (C. maxima Duch.), and zucchini (C. pepo L.) were equally attractive to cucumber beetles. Border treatments did not affect butternut leaf damage, but butternut flowers had the fewest beetles when surrounded by Blue Hubbard or buttercup squash. Yield was highest in the Blue Hubbard and buttercup treatments, but this effect was not statistically significant. Native bees accounted for 87% of pollinator visits, and pollination did not limit yield. There was no evidence that border crops competed with the main crop for pollinators. Our results suggest that both buttercup squash and zucchini may be viable alternatives to Blue Hubbard as borders for the main crop of butternut squash. Thus, growers may have multiple border options that reduce pesticide use, effectively manage pests, and do not disturb mutualist interactions with pollinators.

Scintillation and ionization yields produced by α-particles in high-density gaseous xenon

International Nuclear Information System (INIS)

Kusano, H.; Ishikawa, T.; Lopes, J.A.M.; Miyajima, M.; Shibamura, E.; Hasebe, N.

2012-01-01

The average numbers of scintillation photons and liberated electrons produced by 5.49-MeV α-particles were measured in high-density gaseous xenon. The density range is 0.12–1.32 g/cm 3 for scintillation measurements at zero electric field, and 0.12–1.03 g/cm 3 for the scintillation and ionization measurements under various electric fields. The density dependence of scintillation yield at zero electric field was observed. The W s -value, which is defined as the average energy expended per photon, increases with density and becomes almost constant in the density range above 1.0 g/cm 3 . Anti-correlations between average numbers of scintillation photons and liberated electrons were found to vary with density. It was also found that the total number of scintillation photons and liberated electrons decreases with increasing density. Several possible reasons for the variation in scintillation and ionization yields with density are discussed.

Density-dependent electron scattering in photoexcited GaAs in strongly diffusive regime

DEFF Research Database (Denmark)

Mics, Zoltán; D’Angio, Andrea; Jensen, Søren A.

2013-01-01

In a series of systematic optical pump–terahertz probe experiments, we study the density-dependent electron scattering rate in photoexcited GaAs in the regime of strong carrier diffusion. The terahertz frequency-resolved transient sheet conductivity spectra are perfectly described by the Drude...... model, directly yielding the electron scattering rates. A diffusion model is applied to determine the spatial extent of the photoexcited electron-hole gas at each moment after photoexcitation, yielding the time-dependent electron density, and hence the density-dependent electron scattering time. We find...

High-Yield Synthesis of Zinc Oxide Nanoparticles from Bicontinuous Microemulsions

Directory of Open Access Journals (Sweden)

S. López-Cuenca

2011-01-01

Full Text Available The high-yield synthesis of zinc oxide (ZnO primary nanoparticles with high purity and with diameters between 6 and 22 nm using bicontinuous microemulsions is reported in this work. The ZnO nanoparticles were made by hydrolysis of Zn(NO32 with NaOH aqueous solution and precipitation, followed by calcination of the precipitate. Higher yields and productivities of ZnO nanoparticles were obtained compared to values produced with w/o micremulsions reported in the literature. Particles were characterized by transmission electronic microscopy (TEM, X-ray diffraction, and atomic absorption spectroscopy.

Electron Stimulated Desorption of Condensed Gases on Cryogenic Surfaces

CERN Document Server

Tratnik, H; Hilleret, Noël

2005-01-01

In ultra-high vacuum systems outgassing from vacuum chamber walls and desorption from surface adsorbates are usually the factors which in°uence pressure and residual gas composition. In particular in beam vacuum systems of accelerators like the LHC, where surfaces are exposed to intense synchro- tron radiation and bombardment by energetic ions and electrons, properties like the molecular desorption yield or secondary electron yield can strongly in°uence the performance of the accelerator. In high-energy particle accelerators operating at liquid helium temperature, cold surfaces are exposed to the bombardment of energetic photons, electrons and ions. The gases released by the subsequent desorption are re-condensed on the cold surfaces and can be re-desorbed by the impinging electrons and ions. The equilibrium coverage reached on the surfaces exposed to the impact of energetic particles depends on the desorption yield of the condensed gases and can a®ect the operation of the accelerator by modifying th...

Comparisons of different monetary policies in China with yield curve information

OpenAIRE

Pang, Iris Ai Jao

2010-01-01

This work compares the effectiveness of quantity-based and price-based monetary policies in China using FAVAR. This essay is the pioneer to identify the 1-year lending rate and deposit rate as the policy rates, and includes yield curve information in the analysis. It is found that effects of tightening monetary policies in China follow largely the stylized facts of long run neutrality of money on real activities, a long term fall in inflation and a short term rise in interest rates.

COMPARISON OF SLAUGHTER YIELD AND CARCASS TISSUE COMPOSITION IN BROILER CHICKENS OF VARIOUS ORIGIN

Directory of Open Access Journals (Sweden)

DARIUSZ KOKOSZYŃSKI

2008-07-01

Full Text Available Slaughter yield and carcass tissue composition were compared in three different broiler chicken production sets. The highest body weight (1892.5 g, eviscerated carcass weight with neck (1406.9 g and slaughter yield (74.5% were found in Ross 308 chickens, whilst the lowest values of these traits occurred in JV chickens (respectively: 1753.3; 1288.2 g; 73.3%. The highest muscle contents (45.4% breast muscles and leg muscles in carcass and the lowest fattiness (7.9% skin with subcutaneous fat and 1.5% abdominal fat were found in Hubbard Evolution chickens.

Recent studies on photoelectron and secondary electron yields of TiN and NEG coatings using the KEKB positron ring

International Nuclear Information System (INIS)

Suetsugu, Y.; Kanazawa, K.; Shibata, K.; Hisamatsu, H.

2007-01-01

In order to obtain a method to suppress electron-cloud instability (ECI), the photoelectron and the secondary electron yields (PEY and SEY) of a TiN coating and an NEG (Ti-Zr-V) coating on copper have been studied so far by using the KEK B-factory (KEKB) positron ring. Recently, test chambers with these coatings were installed at a straight section of the ring where the irradiated photon density was considerably smaller than that at the arc section of a previous experiment. The number of electrons around beams was measured by an electron current monitor; this measurement was performed up to a stored beam current of approximately 1700 mA (1389 bunches). For the entire range of the beam current, the electron currents of the NEG-coated and the TiN-coated chambers were clearly smaller as compared to those of the uncoated copper chamber by the factors of 2-3 and 3-4, respectively. The small photon density, that is, the weak effect of photoelectrons, elucidated the differences in the SEYs of these coatings when compared to the measurements at the arc section. By assuming almost the same PEY (η e ) values obtained in the previous study, the maximum SEY (δ max ) for the TiN and NEG coatings and the copper chamber was again estimated based on a previously developed simulation. The evaluated δ max values for these three surfaces were in the ranges of 0.8-1.0, 1.0-1.15, and 1.1-1.25, respectively. These values were consistent with the values obtained so far. As an application of the simulation, the effective η e , η e-eff (which included the geometrical effect of the antechamber) and δ max values were also estimated for copper chambers with one or two antechambers. These chambers were installed in an arc section and a wiggler section, respectively. The evaluated η e-eff and δ max values were approximately 0.008 and 1.2, and 0.04 and 1.2, respectively, where η e =0.28 was assumed on the side wall. As expected, the η e-eff values were considerably smaller than those

B-side charge separation in bacterial photosynthetic reaction centers: nanosecond time scale electron transfer from HB- to QB.

Science.gov (United States)

Kirmaier, Christine; Laible, Philip D; Hanson, Deborah K; Holten, Dewey

2003-02-25

We report time-resolved optical measurements of the primary electron transfer reactions in Rhodobacter capsulatus reaction centers (RCs) having four mutations: Phe(L181) --> Tyr, Tyr(M208) --> Phe, Leu(M212) --> His, and Trp(M250) --> Val (denoted YFHV). Following direct excitation of the bacteriochlorophyll dimer (P) to its lowest excited singlet state P, electron transfer to the B-side bacteriopheophytin (H(B)) gives P(+)H(B)(-) in approximately 30% yield. When the secondary quinone (Q(B)) site is fully occupied, P(+)H(B)(-) decays with a time constant estimated to be in the range of 1.5-3 ns. In the presence of excess terbutryn, a competitive inhibitor of Q(B) binding, the observed lifetime of P(+)H(B)(-) is noticeably longer and is estimated to be in the range of 4-8 ns. On the basis of these values, the rate constant for P(+)H(B)(-) --> P(+)Q(B)(-) electron transfer is calculated to be between approximately (2 ns)(-)(1) and approximately (12 ns)(-)(1), making it at least an order of magnitude smaller than the rate constant of approximately (200 ps)(-)(1) for electron transfer between the corresponding A-side cofactors (P(+)H(A)(-) --> P(+)Q(A)(-)). Structural and energetic factors associated with electron transfer to Q(B) compared to Q(A) are discussed. Comparison of the P(+)H(B)(-) lifetimes in the presence and absence of terbutryn indicates that the ultimate (i.e., quantum) yield of P(+)Q(B)(-) formation relative to P is 10-25% in the YFHV RC.

Investigation of transient dynamics of capillary assisted particle assembly yield

Energy Technology Data Exchange (ETDEWEB)

Virganavičius, D. [Institute of Materials Science, Kaunas University of Technology, K. Baršausko St. 59, Kaunas LT-51423 (Lithuania); Laboratory of Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Juodėnas, M. [Institute of Materials Science, Kaunas University of Technology, K. Baršausko St. 59, Kaunas LT-51423 (Lithuania); Tamulevičius, T., E-mail: tomas.tamulevicius@ktu.lt [Institute of Materials Science, Kaunas University of Technology, K. Baršausko St. 59, Kaunas LT-51423 (Lithuania); Department of Physics, Kaunas University of Technology, Studentų St. 50, Kaunas LT-51368 (Lithuania); Schift, H. [Laboratory of Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Tamulevičius, S. [Institute of Materials Science, Kaunas University of Technology, K. Baršausko St. 59, Kaunas LT-51423 (Lithuania); Department of Physics, Kaunas University of Technology, Studentų St. 50, Kaunas LT-51368 (Lithuania)

2017-06-01

Highlights: • Regular particles arrays were assembled by capillary force assisted deposition. • Deposition yield dynamics was investigated at different thermal velocity regimes. • Yield transient behavior was approximated with logistic function. • Pattern density influence for switching behavior was assessed. - Abstract: In this paper, the transient behavior of the particle assembly yield dynamics when switching from low yield to high yield deposition at different velocity and thermal regimes is investigated. Capillary force assisted particle assembly (CAPA) using colloidal suspension of green fluorescent 270 nm diameter polystyrene beads was performed on patterned poly (dimethyl siloxane) substrates using a custom-built deposition setup. Two types of patterns with different trapping site densities were used to assess CAPA process dynamics and the influence of pattern density and geometry on the deposition yield transitions. Closely packed 300 nm diameter circular pits ordered in hexagonal arrangement with 300 nm pitch, and 2 × 2 mm{sup 2} square pits with 2 μm spacing were used. 2-D regular structures of the deposited particles were investigated by means of optical fluorescence and scanning electron microscopy. The fluorescence micrographs were analyzed using a custom algorithm enabling to identify particles and calculate efficiency of the deposition performed at different regimes. Relationship between the spatial distribution of particles in transition zone and ambient conditions was evaluated and quantified by approximation of the yield profile with a logistic function.

Optimizing rice yields while minimizing yield-scaled global warming potential.

Science.gov (United States)

Pittelkow, Cameron M; Adviento-Borbe, Maria A; van Kessel, Chris; Hill, James E; Linquist, Bruce A

2014-05-01

To meet growing global food demand with limited land and reduced environmental impact, agricultural greenhouse gas (GHG) emissions are increasingly evaluated with respect to crop productivity, i.e., on a yield-scaled as opposed to area basis. Here, we compiled available field data on CH4 and N2 O emissions from rice production systems to test the hypothesis that in response to fertilizer nitrogen (N) addition, yield-scaled global warming potential (GWP) will be minimized at N rates that maximize yields. Within each study, yield N surplus was calculated to estimate deficit or excess N application rates with respect to the optimal N rate (defined as the N rate at which maximum yield was achieved). Relationships between yield N surplus and GHG emissions were assessed using linear and nonlinear mixed-effects models. Results indicate that yields increased in response to increasing N surplus when moving from deficit to optimal N rates. At N rates contributing to a yield N surplus, N2 O and yield-scaled N2 O emissions increased exponentially. In contrast, CH4 emissions were not impacted by N inputs. Accordingly, yield-scaled CH4 emissions decreased with N addition. Overall, yield-scaled GWP was minimized at optimal N rates, decreasing by 21% compared to treatments without N addition. These results are unique compared to aerobic cropping systems in which N2 O emissions are the primary contributor to GWP, meaning yield-scaled GWP may not necessarily decrease for aerobic crops when yields are optimized by N fertilizer addition. Balancing gains in agricultural productivity with climate change concerns, this work supports the concept that high rice yields can be achieved with minimal yield-scaled GWP through optimal N application rates. Moreover, additional improvements in N use efficiency may further reduce yield-scaled GWP, thereby strengthening the economic and environmental sustainability of rice systems. © 2013 John Wiley & Sons Ltd.

High-field electron-photon interactions

International Nuclear Information System (INIS)

Hartemann, F V.

1999-01-01

Recent advances in novel technologies (including chirped-pulse amplification, femtosecond laser systems operating in the TW-PW range, high-gradient rf photoinjectors, and synchronized relativistic electron bunches with subpicosecond durations and THz bandwidths) allow experimentalists to study the interaction of relativistic electrons with ultrahigh-intensity photon fields. Ponderomotive scattering can accelerate these electrons with extremely high gradients in a three-dimensional vacuum laser focus. The nonlinear Doppler shift induced by relativistic radiation pressure in Compton backscattering is shown to yield complex nonlinear spectra which can be modified by using temporal laser pulse shaping techniques. Colliding laser pulses, where ponderomotive acceleration and Compton backscattering are combined, could also yield extremely short wavelength photons. Finally, one expects strong radiative corrections when the Doppler-upshifted laser wavelength approaches the Compton scale. These are discussed within the context of high-field classical electrodynamics, a new discipline borne out of the aforementioned innovations

Comparison of the compressive yield response of aggregated suspensions: Pressure filtration, centrifugation, and osmotic consolidation

International Nuclear Information System (INIS)

Miller, K.T.; Melant, R.M.; Zukoski, C.F.

1996-01-01

The compressive rheological responses of suspensions containing flocculated kaolin, alumina (average particle sizes of 0.2 and 0.5 microm), and hydrous zirconia (average particle sizes of 8, 57, and 139 nm) particles have been measured using three different techniques: pressure filtration, volume fraction profile during centrifugation, and sediment height during centrifugation at multiple spinning speeds. While the volume fraction profile technique appears to be experimentally most robust, equivalent responses are found using the different techniques, indicating that the compressive yield stress is a material property of a given suspension. The compressive yield stress of each suspension increases rapidly with volume fraction but cannot be generally described using simple power-law or exponential fits. The compressive yield stress also increases with the inverse square of particle size. The packing behavior of the suspensions undergoing osmotic consolidation is compared with the mechanical compressive yield response. Some suspensions exhibited the same packing behavior as in the mechanical techniques, while others consistently packed to higher densities during osmotic consolidation. Although equivalent osmotic and mechanical loads do not always result in the same volume fractions, the similar increases in volume fraction with applied driving force suggest that both the osmotic and mechanical techniques are controlled by the force needed to rearrange the particle network

Influence of micronutrients and their method of application on yield and yield components of sunflower

International Nuclear Information System (INIS)

Baraich, A.A.K.; Gandahi, A.W.

2016-01-01

The sunflower (Helianthus annuus L.) has been recognized as a crop with high potentials that can successfully meet future oil requirements of the country. Formulation of micronutrients (MN) based fertilizer, in terms of application rate and method, and uptake of MN by sunflower has the ability not only to ensure nutrients availability to plants particularly in MN-limiting environments but also can manipulate the environmental hazards associated with over inorganic fertilization. To support this view, clear experimental evidence is still lacking. In addition, the current experiments aimed to evaluate the influence of MN and its method of application on yield and yield components of sunflower cultivars/hybrids. Three sunflower cultivars (HO-1, Hysun-39 and Ausigold-62) along with three MN (Z, B and Fe) and two application methods (soil and foliar) were used in the experiment. Three Zn application rate (3, 5 and 8 kg ha-1) along with 0.75 kg ha-1 B and 0.30 kg Fe ha-1 were used in four combinations such as 0-0-0, 0-0.75-0.30, 0-0.75-0.30, 3-0.75-0.30, 5-0.75-0.30, 8-0.75-0.30 kg Z, B and Fe ha-1, respectively. A control (no MN) treatment was also included for comparison. Two year averaged study exhibited that foliar application of Zn, B and Fe at rate of 8-0.30-0.75 kg ha-1 increased stem girth, head diameter, number of seeds head-1, seed weight head-1, seed index, oil content and seed yield by 21%, 27%, 13%, 34%, 19%, 24 and 31%, respectively over control. Among cultivars/hybrids, the hybrids HO-1 and Hysun-39 had taller plants, seed weight head-1, seeds head-1 and earlier in flowering and maturity. Flowering and maturity was delayed in Ausi Gold-62 with higher seed index and oil content. It is concluded that foliar application of micronutrients at the rate of 8+0.75+0.30 Zn, B and Fe kg ha-1 had substantially improved yield and yield related traits of sunflower cultivars HO-1, Hysun-39 and Ausi gold-62. (author)

Mass production of multi-wall carbon nanotubes by metal dusting process with high yield

Energy Technology Data Exchange (ETDEWEB)

Ghorbani, H. [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Narmak, Tehran (Iran, Islamic Republic of); Rashidi, A.M., E-mail: Rashidiam@ripi.ir [Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), West Blvd. Azadi Sport Complex, P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of); Rastegari, S.; Mirdamadi, S. [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Narmak, Tehran (Iran, Islamic Republic of); Alaei, M. [Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), West Blvd. Azadi Sport Complex, P.O. Box 14665-1998, Tehran (Iran, Islamic Republic of)

2011-05-15

Research highlights: {yields} Synthesis of carbon nanotubes over Fe-Ni nanoparticles supported alloy 304L. {yields} Production of carbon nanotubes with high yield (700-1000%) and low cost catalyst. {yields} Optimum growth condition is CO/H{sub 2} = 1/1, 100 cm{sup 3}/min, at 620 {sup o}C under long term repetitive thermal cycling. {yields} Possibility of the mass production by metal dusting process with low cost. -- Abstract: Carbon nanotube materials were synthesized over Fe-Ni nanoparticles generated during disintegration of the surface of alloy 304L under metal dusting environment. The metal dusting condition was simulated and optimized through exposing stainless steel samples during long term repetitive thermal cycling in CO/H{sub 2} = 1/1, total gas flow rate 100 cm{sup 3}/min, at 620 {sup o}C for 300 h. After reaction, surface morphology of the samples and also carbonaceous deposition which had grown on sample surfaces were examined by stereoscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results revealed that multi-wall carbon nanotubes could be formed over nanocatalyst generated on the alloy surface by exploiting metal dusting process. By optimization of reaction parameters the yields of carbon nanotube materials obtained were 700-1000%. Also it has been shown herein that the amount of carbon nanotube materials remarkably increases when the reaction time is extended up to 300 h, indicating a possibility of the mass production by this easy method.

Evaluation of lens dose from anterior electron beams: comparison of Pinnacle and Gafchromic EBT3 film.

Science.gov (United States)

Sonier, Marcus; Wronski, Matt; Yeboah, Collins

2015-03-08

Lens dose is a concern during the treatment of facial lesions with anterior electron beams. Lead shielding is routinely employed to reduce lens dose and minimize late complications. The purpose of this work is twofold: 1) to measure dose pro-files under large-area lead shielding at the lens depth for clinical electron energies via film dosimetry; and 2) to assess the accuracy of the Pinnacle treatment planning system in calculating doses under lead shields. First, to simulate the clinical geometry, EBT3 film and 4 cm wide lead shields were incorporated into a Solid Water phantom. With the lead shield inside the phantom, the film was positioned at a depth of 0.7 cm below the lead, while a variable thickness of solid water, simulating bolus, was placed on top. This geometry was reproduced in Pinnacle to calculate dose profiles using the pencil beam electron algorithm. The measured and calculated dose profiles were normalized to the central-axis dose maximum in a homogeneous phantom with no lead shielding. The resulting measured profiles, functions of bolus thickness and incident electron energy, can be used to estimate the lens dose under various clinical scenarios. These profiles showed a minimum lead margin of 0.5 cm beyond the lens boundary is required to shield the lens to ≤ 10% of the dose maximum. Comparisons with Pinnacle showed a consistent overestimation of dose under the lead shield with discrepancies of ~ 25% occur-ring near the shield edge. This discrepancy was found to increase with electron energy and bolus thickness and decrease with distance from the lead edge. Thus, the Pinnacle electron algorithm is not recommended for estimating lens dose in this situation. The film measurements, however, allow for a reasonable estimate of lens dose from electron beams and for clinicians to assess the lead margin required to reduce the lens dose to an acceptable level.

Preparation of {sup 114m}In low energy conversion electron sources

Energy Technology Data Exchange (ETDEWEB)

Wrede, C., E-mail: wrede@uw.ed [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Filippone, B.W. [Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Garcia, A.; Harper, G.C. [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Lassell, S. [Department of Nuclear Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Liu, J. [Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Mendenhall, M.P. [Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Palmer, A.S.C. [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Pattie, R.W. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Will, D.I. [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Young, A.R. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)

2011-05-15

Highlights: {yields} Controlled ion implantation of In-113 into thin Al substrate. {yields} Production of In-114m (half life = 50 days) by neutron irradiation. {yields} Use of In-114m as a source of electron lines and continuum for calibrations. {yields} Source reactivation by short neutron irradiation. -- Abstract: The preparation of {sup 114m}In sources of conversion electrons in the energy range 162-190 keV and {beta} continuum with a 1989 keV endpoint via ion implantation of {sup 113}In into Al substrates and subsequent irradiation by thermal and epi-thermal neutrons in a nuclear reactor is described.

Measurements of barium photocathode quantum yields at four excimer laser wavelengths

International Nuclear Information System (INIS)

Van Loy, M.D.; Young, A.T.; Leung, K.N.

1992-06-01

The electron quantum yields from barium cathodes excited by excimer laser radiation at 193, 248, 308, and 351 nm have been determined. Experiments with different cathode surface preparation techniques reveal that deposition of barium film a few microns thick on a clean copper surface under moderate vacuum conditions achieves relatively high quantum efficiencies. Quantum yields measured from surfaces prepared in this manner are 2.3 x 10 -3 at 193 nm, 7.6 x 10 - 4 at 248 nm, 6.1 x 10 -4 at 308 nm, and 4.0 x 10 -4 at 351 nm. Other preparation techniques, such as laser cleaning of a solid barium surface, produced quantum yields that were at least an order of magnitude lower than these values

Evaluation of Yield and Yield Components of Some Pinto bean (Phaseolus vulgaris L. Genotypes under Late Season Water Deficit Conditions

Directory of Open Access Journals (Sweden)

somayyeh soheili movahhed

2017-10-01

indicated that Ks21189 genotype showed maximum number of pod perplant (9.2, number of grain per pod (2.91, 100 grain weight, grain yield (741.6 Kg.Ha-1, biological yield (2857 Kg.Ha-1 and Harvest Index (27.31% under drought stress conditions. In addition, this genotype had the least reduction for all traits under water limitation conditions in comparison to control. These findings confirm the resistance of Ks21189 genotype to drought stress and stimulating this genotype to least reduction in Grain yield under water limitation conditions. Minimum number of pod per plant (4.52, number of grain per pod (1.62, grain yield (503.1 Kg.Ha-1, biological yield (2301.6 Kg.Ha-1 and Harvest Index (22.66% was obtained in sadri genotype under drought conditions. Sadri genotype was identified as water deficit stress sensitive genotypes with reduction of yield up to 80.18%. In all genotypes, water deficit stress reduced grain yield due to reduced yield components (number of pod per plant, number of grain per pod and 100 grain weight. Conclusion The results of this experiment showed that water deficit stress on yield and yield components of bean genotypes had a negative effect. The highest and lowest yield and yield components were obtained from normal irrigation and drought stress treatments, respectively. Ks21189 genotype was more stable in water deficit treatment than other genotypes; however grain yield reduce in normal irrigation treatment was lower than other genotypes. Therefore, it seems that this genotype can be used as an appropriate genotype for supplemental evaluation in water deficit stress conditions. Correlation analysis showed significant and positive correlation between biological yield, number of pods per plant, number of grains per pod with grain yield. We concluded that genotypes with higher biological yield under drought stress conditions can produce maximum number of pods per plant, number of grains per pod and grain yield. Acknowledgments We would like to express our

Electron emission from Inconel under ion bombardment

International Nuclear Information System (INIS)

Alonso, E.V.; Baragiola, R.A.; Ferron, J.; Oliva-Florio, A.

1979-01-01

Electron yields from clean and oxidized Inconel 625 surfaces have been measured for H + ,H 2 + ,He + ,O + and Ar + ions at normal incidence in the energy range 1.5 to 40 keV. These measurements have been made under ultrahigh vacuum and the samples were freed of surface contaminants by bombarding with high doses of either 20 keV H 2 + or 30 keV Ar + ions. Differences in yields of oxidized versus clean surfaces are explained in terms of differences in the probability that electrons internally excited escape upon reaching the surface. (author)

Response of Barley Double Haploid Lines to the Grain Yield and Morphological Traits under Water Deficit Stress Conditions

Directory of Open Access Journals (Sweden)

Maroof Khalily

2017-04-01

Full Text Available To study the relationships of grain yield and some of agro-morphological traits in 40 doubled haploid (DH lines along with parental and three check genotypes in a randomized complete block design with two replications under two water regimes (normal and stress were evaluated during 2011-2012 and 2012-2013 growing seasons. Combined analysis of variance showed significant difference for all the traits in terms of the year, water regimes, lines, and and line × year. Comparison of group means, between non-stress and stress conditions, showed that DH lines had the lowest reduction percentage for the number of grains per spike, thousand grain weight, grain yield and biological yield as opposed to check genotypes. The correlation between grain yield with biological yield, harvest index, thousand grain weight, and hectoliter of kernel weight in both conditions, were highly significant and positive. Based on stepwise regression the peduncle length, number of seeds per spike, thousand seed weight, and hectoliter of kernel weight had important effect on increasing seed yield. The result of path analysis showed that these traits had the highest direct effect on grain yield. Based on mean comparisons of morphological characters as well as STI and GMP indices it can be concluded that lines No.11, 13, 14, 24, 29, 30, 35 and 39 were distinguished to be desirable lines for grain yield and their related traits and also tolerant lines in terms of response to drought stress conditions.

Syringe injectable electronics

Science.gov (United States)

Hong, Guosong; Zhou, Tao; Jin, Lihua; Duvvuri, Madhavi; Jiang, Zhe; Kruskal, Peter; Xie, Chong; Suo, Zhigang; Fang, Ying; Lieber, Charles M.

2015-01-01

Seamless and minimally-invasive three-dimensional (3D) interpenetration of electronics within artificial or natural structures could allow for continuous monitoring and manipulation of their properties. Flexible electronics provide a means for conforming electronics to non-planar surfaces, yet targeted delivery of flexible electronics to internal regions remains difficult. Here, we overcome this challenge by demonstrating syringe injection and subsequent unfolding of submicrometer-thick, centimeter-scale macroporous mesh electronics through needles with a diameter as small as 100 micrometers. Our results show that electronic components can be injected into man-made and biological cavities, as well as dense gels and tissue, with > 90% device yield. We demonstrate several applications of syringe injectable electronics as a general approach for interpenetrating flexible electronics with 3D structures, including (i) monitoring of internal mechanical strains in polymer cavities, (ii) tight integration and low chronic immunoreactivity with several distinct regions of the brain, and (iii) in vivo multiplexed neural recording. Moreover, syringe injection enables delivery of flexible electronics through a rigid shell, delivery of large volume flexible electronics that can fill internal cavities and co-injection of electronics with other materials into host structures, opening up unique applications for flexible electronics. PMID:26053995

A Comparison of Performances of Electronic and Electromechanical ...

African Journals Online (AJOL)

The Ferraris (electromechanical) energy meter has had predominance in the metering of energy consumption using the alternating current supply system. Electronic energy meters are gaining popularity because of the possibility of remote reading and controllable non uniform rate of billing. In this work, an electronic energy ...

Studying electron-PAG interactions using electron-induced fluorescence

Science.gov (United States)

Narasimhan, Amrit; Grzeskowiak, Steven; Ostrander, Jonathan; Schad, Jonathon; Rebeyev, Eliran; Neisser, Mark; Ocola, Leonidas E.; Denbeaux, Gregory; Brainard, Robert L.

2016-03-01

In extreme ultraviolet (EUV) lithography, 92 eV photons are used to expose photoresists. Typical EUV resists are organic-based and chemically amplified using photoacid generators (PAGs). Upon exposure, PAGs produce acids which catalyze reactions that result in changes in solubility. In EUV lithography, photo- and secondary electrons (energies of 10- 80 eV) play a large role in PAG acid-production. Several mechanisms for electron-PAG interactions (e.g. electron trapping, and hole-initiated chemistry) have been proposed. The aim of this study is to explore another mechanism - internal excitation - in which a bound PAG electron can be excited by receiving energy from another energetic electron, causing a reaction that produces acid. This paper explores the mechanism of internal excitation through the analogous process of electron-induced fluorescence, in which an electron loses energy by transferring that energy to a molecule and that molecule emits a photon rather than decomposing. We will show and quantify electron-induced fluorescence of several fluorophores in polymer films to mimic resist materials, and use this information to refine our proposed mechanism. Relationships between the molecular structure of fluorophores and fluorescent quantum yield may aid in the development of novel PAGs for EUV lithography.

Influence of polymer charge on the shear yield stress of silica aggregated with adsorbed cationic polymers.

Science.gov (United States)

Zhou, Ying; Yu, Hai; Wanless, Erica J; Jameson, Graeme J; Franks, George V

2009-08-15

Flocs were produced by adding three cationic polymers (10% charge density, 3.0x10(5) g/mol molecular weight; 40% charge density, 1.1x10(5) g/mol molecular weight; and 100% charge density, 1.2x10(5) g/mol molecular weight) to 90 nm diameter silica particles. The shear yield stresses of the consolidated sediment beds from settled and centrifuged flocs were determined via the vane technique. The polymer charge density plays an important role in influencing the shear yield stresses of sediment beds. The shear yield stresses of sediment beds from flocs induced by the 10% charged polymer were observed to increase with an increase in polymer dose, initial solid concentration and background electrolyte concentration at all volume fractions. In comparison, polymer dose has a marginal effect on the shear yield stresses of sediment beds from flocs induced by the 40% and 100% charged polymers. The shear yield stresses of sediments from flocs induced by the 40% charged polymer are independent of salt concentration whereas the addition of salt decreases the shear yield stresses of sediments from flocs induced by the 100% charged polymer. When flocculated at the optimum dose for each polymer (12 mg/g silica for the 10% charged polymer at 0.03 M NaCl, 12 mg/g for 40% and 2 mg/g for 100%), shear yield stress increases as polymer charge increases. The effects observed are related to the flocculation mechanism (bridging, patch attraction or charge neutralisation) and the magnitude of the adhesive force. Comparison of shear and compressive yield stresses show that the network is only slightly weaker in shear than in compression. This is different than many other systems (mainly salt and pH coagulation) which have shear yield stress much less than compressive yield stress. The existing models relating the power law exponent of the volume fraction dependence of the shear yield stress to the network fractal structure are not satisfactory to predict all the experimental behaviour.

A systematic review of portable electronic technology for health education in resource-limited settings.

Science.gov (United States)

McHenry, Megan S; Fischer, Lydia J; Chun, Yeona; Vreeman, Rachel C

2017-08-01

The objective of this study is to conduct a systematic review of the literature of how portable electronic technologies with offline functionality are perceived and used to provide health education in resource-limited settings. Three reviewers evaluated articles and performed a bibliography search to identify studies describing health education delivered by portable electronic device with offline functionality in low- or middle-income countries. Data extracted included: study population; study design and type of analysis; type of technology used; method of use; setting of technology use; impact on caregivers, patients, or overall health outcomes; and reported limitations. Searches yielded 5514 unique titles. Out of 75 critically reviewed full-text articles, 10 met inclusion criteria. Study locations included Botswana, Peru, Kenya, Thailand, Nigeria, India, Ghana, and Tanzania. Topics addressed included: development of healthcare worker training modules, clinical decision support tools, patient education tools, perceptions and usability of portable electronic technology, and comparisons of technologies and/or mobile applications. Studies primarily looked at the assessment of developed educational modules on trainee health knowledge, perceptions and usability of technology, and comparisons of technologies. Overall, studies reported positive results for portable electronic device-based health education, frequently reporting increased provider/patient knowledge, improved patient outcomes in both quality of care and management, increased provider comfort level with technology, and an environment characterized by increased levels of technology-based, informal learning situations. Negative assessments included high investment costs, lack of technical support, and fear of device theft. While the research is limited, portable electronic educational resources present promising avenues to increase access to effective health education in resource-limited settings, contingent

Effect of Integrated Nutrient Management on Yield and Yield ...

African Journals Online (AJOL)

Declining soil fertility is one of the major problems causing yield reduction of barley ... (VC) with inorganic NP on growth, yield and yield components of food barley. ... The experiments were laid out in a randomized complete block design with ...

Secondary electron emission from 0.5--2.5-MeV protons and deuterons

International Nuclear Information System (INIS)

Thornton, T.A.; Anno, J.N.

1977-01-01

Measurement of the secondary electron currents leaving Al, V, Fe, 316 stainless steel, Nb, and Mo foils undergoing 0.5--2.5-MeV proton and deuteron bombardment were made to determine the secondary electron emission ratios for these ions. The measured secondary electron yields were of the order of 1.0, with the deuterons producing generally higher yields than the protons

Theory of electron degradation and yields of initial molecular species produced by ionizing radiation

International Nuclear Information System (INIS)

Inokuti, M.; Dillon, M.A.; Kimura, M.

1987-01-01

Ionizing radiations generate in matter a large number of energetic electrons, which in turn collide with molecules in matter, produce ions and excited states, and thereby degrade in energy. The description of the consequences of many collision processes to the electrons and to matter is the goal of the electron degradation theory. They summarize the current understanding of this topic, which is important as a basis of radiation chemistry and biology. In addition, they present an initial report of their new work, namely, a generalization of the Spencer-Fano theory to time-dependent cases

The decrease in yield strength in NiAl due to hydrostatic pressure

Science.gov (United States)

Margevicius, R. W.; Lewandowski, J. J.; Locci, I.

1992-01-01

The decrease in yield strength in NiAl due to hydrostatic pressure is examined via a comparison of the tensile flow behavior in the low strain regime at 0.1 MPa for NiAl which was cast, extruded, and annealed for 2 hr at 827 C in argon and very slowly cooled to room temperature. Pressurization to 1.4 GPa produces a subsequent reduction at 0.1 MP in proportional limit by 40 percent as well as a 25-percent reduction in the 0.2-percent offset yield strength, while pressurization with lower pressures produces a similar reduction, although smaller in magnitude.

A comparison of various procedures in photon activation analysis with the same irradiation setup

Energy Technology Data Exchange (ETDEWEB)

Sun, Z.J. [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 (United States); Wells, D. [Physics Department, South Dakota School of Mines and Technology, 501 E. Saint Joseph St., Rapid City, SD 57701 (United States); Segebade, C. [Idaho Accelerator Center, Idaho State University, 921 S. 8th Ave., Pocatello, ID 83209 (United States); Quigley, K.; Chemerisov, S. [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 (United States)

2014-11-15

A sample of known elemental concentrations was activated in the bremsstrahlung photon beam which was created by a pulsed electron LINAC. Several procedures of photon activation analysis, including those applied with/without reference material and with/without photon flux monitor, were conducted to make a comparison of their precision and accuracy in practice. Experimental results have indicated that: (1) relative procedures usually produce better outcome despite that the absolute measurement is straightforward and eliminate the assistance of reference materials; (2) among relative procedures, the method with internal flux monitor yields higher quality of the analytical results. In the article, the pros and cons of each procedure are discussed as well.

Secondary electron measurement and XPS characterization of NEG coatings

International Nuclear Information System (INIS)

Sharma, R. K.; Sinha, Atul K.; Gupta, Nidhi; Nuwad, J.; Jagannath,; Gadkari, S. C.; Singh, M. R.; Gupta, S. K.

2014-01-01

Ternary alloy coatings of IVB and VB materials provide many of benefits over traditional material surfaces such as creation of extreme high vacuum(XHV), lower secondary electron yield(SEY), low photon desorption coefficient. XHV (pressure −10 mbar) is very useful to the study of surfaces of the material in as it is form, high energy particle accelerators(LHC, Photon Factories), synchrotrons (ESRF, Ellectra) etc.. Low secondary electron yield leads to very low multi-pacting utilizes to increase beam life time. In this paper preparation of the coatings and a study of secondary electron yield measurement after heating at different temperatures has been shown also results of their surface characterization based on shift in binding energy has been produced using the surface techniques XPS. Stoichiometry of the film was measured by Energy dispersive x-ray analysis (EDX)

High yield fabrication of chemically reduced graphene oxide field effect transistors by dielectrophoresis

International Nuclear Information System (INIS)

Joung, Daeha; Chunder, A; Zhai, Lei; Khondaker, Saiful I

2010-01-01

We demonstrate high yield fabrication of field effect transistors (FET) using chemically reduced graphene oxide (RGO) sheets. The RGO sheets suspended in water were assembled between prefabricated gold source and drain electrodes using ac dielectrophoresis. With the application of a backgate voltage, 60% of the devices showed p-type FET behavior, while the remaining 40% showed ambipolar behavior. After mild thermal annealing at 200 deg. C, all ambipolar RGO FET remained ambipolar with increased hole and electron mobility, while 60% of the p-type RGO devices were transformed to ambipolar. The maximum hole and electron mobilities of the devices were 4.0 and 1.5 cm 2 V -1 s -1 respectively. High yield assembly of chemically derived RGO FET will have significant impact in scaled up fabrication of graphene based nanoelectronic devices.

Comparison of yield and decay data among JNDC2, ENDF/B-VI and JEF2.2

Energy Technology Data Exchange (ETDEWEB)

Oyamatsu, Kazuhiro; Sagisaka, Mitsuyuki; Miyazono, Toshimitsu [Nagoya Univ. (Japan)

1997-03-01

Fission yields and decay data for fission product summation calculations are compared among JNDC2 and ENDF/B-VI and JEF2.2. Special attention is paid to the summation calculation of the total delayed neutrons per fission because it requires the data of the most unstable nuclides among all fission products. The cumulative fission yields of delayed neutron precursors are found to be appreciably different among the libraries even though values of the independent fission yields and the total number of delayed neutrons are chosen to be in fair agreement with each other. This suggests that there still exist large uncertainties in delayed neutron emission probabilities (or decay chains) for the precursors far from the stability line. (author)

An AES Study of the Room Temperature Surface Conditioning of Technological Metal Surfaces by Electron Irradiation

CERN Document Server

Scheuerlein, C; Taborelli, M; Brown, A; Baker, M A

2002-01-01

The modifications to technological copper and niobium surfaces induced by 2.5 keV electron irradiation have been investigated in the context of the conditioning process occurring in particle accelerator ultra high vacuum systems. Changes in the elemental surface composition have been found using Scanning Auger Microscopy (SAM) by monitoring the carbon, oxygen and metal Auger peak intensities as a function of electron irradiation in the dose range 10-6 to 10-2 C mm-2. The surface analysis results are compared with electron dose dependent secondary electron and electron stimulated desorption yield measurements. Initially the electron irradiation causes a surface cleaning through electron stimulated desorption, in particular of hydrogen. During this period both the electron stimulated desorption and secondary electron yield decrease as a function of electron dose. When the electron dose exceeds 10-4 C mm-2 electron stimulated desorption yields are reduced by several orders of magnitude and the electron beam indu...

Yield trends and yield gap analysis of major crops in the world

OpenAIRE

Hengsdijk, H.; Langeveld, J.W.A.

2009-01-01

This study aims to quantify the gap between current and potential yields of major crops in the world, and the production constraints that contribute to this yield gap. Using an expert-based evaluation of yield gaps and the literature, global and regional yields and yield trends of major crops are quantified, yield gaps evaluated by crop experts, current yield progress by breeding estimated, and different yield projections compared. Results show decreasing yield growth for wheat and rice, but ...

Inelastic cross-sections for electron transport in liquid water: a comparison of dielectric models

International Nuclear Information System (INIS)

Emfietzoglou, D.

2003-01-01

Various methodologies for constructing inelastic cross-sections for low-energy (<10 keV) electron transport in liquid water are presented and compared. They are all based on an optical-data model which provides the dependence on energy loss, and a dispersion algorithm which incorporates the momentum-transfer dependence. A Drude dielectric model was used to analytically represent the optical data. Various dispersion schemes were examined: the Bethe approximation, the δ-oscillator models of Ashley and Liljequist, and two forms of Ritchie's extended-Drude model. They all have been used in Monte-Carlo (MC) codes for analog electron transport in the condensed phase. Results in the form of differential and total inelastic cross-sections are presented. Where possible, comparisons with results of other studies are made. It was found that, despite the application of general constraints (e.g. sum rules), the optical model has a notable influence on the single-collision energy loss spectrum. In addition, both the shape and peak position of the total and differential cross-section distributions depend strongly on the dispersion model adopted. The work is particularly relevant to the development of event-by-event MC transport codes for liquid water, as well as, to the calculations of stopping-powers below the range of applicability of Bethe's formula

Comparison of Monte Carlo simulations of photon/electron dosimetry in microscale applications

International Nuclear Information System (INIS)

Poneja, O.P.; Chawla, R.; Negreanu, C.; Stepanek, J.

2003-01-01

It is important to establish reliable calculational tools to plan and analyse representative microdosimetry experiments in the context of microbeam radiation therapy development. In this paper, an attempt has been made to investigate the suitability of the MCNP4C Monte Carlo code to adequately model photon/electron transport over micron distances. The case of a single cylindrical microbeam of 25-micron diameter incident on a water phantom has been simulated in detail with both MCNP4C and the code PSI-GEANT, for different incident photon energies, to get absorbed dose distributions at various depths, with and without electron transport being considered. In addition, dose distributions calculated for a single microbeam with a photon spectrum representative of the European Synchrotron Radiation Facility (ESRF) have been compared. Finally, a large number of cylindrical microbeams ( a total of 2601 beams, placed on a 200-micron square pitch, covering an area of lcm 2 ) incident on a water phantom have been considered to study cumulative radial dose distributions at different depths. From these distributions, ratios of peak (within the microbeam) to valley (mid-point along the diagonal connecting two microbeams) dose values have been determined. The various comparisons with PSI-GEANT results have shown that MCNP4C, with its high flexibility in terms of its numerous source and geometry description options, variance reduction methods, detailed error analysis, statistical checks and different tally types, can be a valuable tool for the analysis of microbeam experiments. Copyright (2003) Australasian College of Physical Scientists and Engineers in Medicine

Equity yields

NARCIS (Netherlands)

Vrugt, E.; van Binsbergen, J.H.; Koijen, R.S.J.; Hueskes, W.

2013-01-01

We study a new data set of dividend futures with maturities up to ten years across three world regions: the US, Europe, and Japan. We use these asset prices to construct equity yields, analogous to bond yields. We decompose the equity yields to obtain a term structure of expected dividend growth

3 to 15 keV Ar+ induced Auger electron emission from Si and Ar

International Nuclear Information System (INIS)

Kempf, J.; Kaus, G.

1977-01-01

Ar + induced Auger electrons from Si and Ar were investigated at bombardment energies between 3-15 keV and target currents of a few μA. The Auger electron yields were compared with secondary ion yields of Si and Ar by simultaneous SIMS-AES measurements. In the ion induced Auger spectra of Si five Auger peaks and in the Ar spectra three Auger peaks were observed. The ion induced Auger electron yield of Si and Ar were found to be strongly dependent upon the primary ion energy. 'Bulk like' and 'atomic like' Auger transitions of ion induced Auger electrons of Si were observed. (orig.) [de

Diffusion length of minority carriers in scanning electron beam annealed silicon

International Nuclear Information System (INIS)

Smith, H.J.; Cilliers, R.; Bontemps, A.

1982-01-01

Ion implantation has advantages for solar cell production, but necessitates an annealing step. Various new transitory annealing methods have appeared recently. A particularly attractive method is multi-scan electron beam annealing of thermally isolated wafers. Energy is applied homogeneously over the whole target surface and the temperature rises throughout the thickness. Backscattering analysis shows good recrystallization in seconds. However the effect of this total heating on the diffusion length (Lsub(D)) must be investigated particularly in view of the degradation of Lsub(D) due to high temperature oven annealing. The semiconductor-electrolyte diode method was set up to measure the current generated in the cell due to the creation and diffusion of carriers in the silicon under photon irradiation. Comparison with a theoretical model yields Lsub(D). It appears that 3mA.cm - 2 of 15keV electrons recrystallizes damage in 2.5 seconds and does not decrease Lsub(D) in the bulk. In 4 seconds the Lsub(D) decreases and dopant diffusion occurs. On technical grounds this method can thus be applied for solar cell production. (Auth.)

Time-dependent aspects of electron degradation: 4, Subexcitation electrons in nitrogen and carbon dioxide

International Nuclear Information System (INIS)

Kimura, Mineo; Inokuti, Mitio; Kowari, Ken-ichi; Dillon, M.A.; Pagnamenta, A.

1988-01-01

We discuss here the temporal behavior of subexcitation electrons and the yields of products due to these subexcitation electrons. Our examples concern cases in which resonance scattering of electrons occurs, such as vibrational and rotational excitation in N 2 and negative-ion formation in CO 2 . One focus of the present work is a test of the continuous-slowing-down-approximation (CSDA) which we compare to the full solution of the time-dependent Spencer-Fano theory, which has been developed recently. 11 refs., 6 figs., 1 tab

Secondary-electron yield from Au induced by highly charged Ta ions

Czech Academy of Sciences Publication Activity Database

Krása, Josef; Láska, Leoš; Stöckli, M. P.; Fry, D.

2001-01-01

Roč. 173, - (2001), s. 281-286 ISSN 0168-583X R&D Projects: GA AV ČR IAA1010819 Institutional research plan: CEZ:AV0Z1010914 Keywords : highly charged ion-surface interaction * ion-induced electron emission * angle impact effect Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.041, year: 2001

Comparison of Electron Imaging Modes for Dimensional Measurements in the Scanning Electron Microscope.

Science.gov (United States)

Postek, Michael T; Vladár, András E; Villarrubia, John S; Muto, Atsushi

2016-08-01

Dimensional measurements from secondary electron (SE) images were compared with those from backscattered electron (BSE) and low-loss electron (LLE) images. With the commonly used 50% threshold criterion, the lines consistently appeared larger in the SE images. As the images were acquired simultaneously by an instrument with the capability to operate detectors for both signals at the same time, the differences cannot be explained by the assumption that contamination or drift between images affected the SE, BSE, or LLE images differently. Simulations with JMONSEL, an electron microscope simulator, indicate that the nanometer-scale differences observed on this sample can be explained by the different convolution effects of a beam with finite size on signals with different symmetry (the SE signal's characteristic peak versus the BSE or LLE signal's characteristic step). This effect is too small to explain the >100 nm discrepancies that were observed in earlier work on different samples. Additional modeling indicates that those discrepancies can be explained by the much larger sidewall angles of the earlier samples, coupled with the different response of SE versus BSE/LLE profiles to such wall angles.

Comparing electron tomography and HRTEM slicing methods as tools to measure the thickness of nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Alloyeau, D., E-mail: alloyeau.damien@gmail.com [Laboratoire Materiaux et Phenomenes Quantiques, Universite Paris 7/CNRS, UMR 7162, 2 Place Jussieu, 75251 Paris (France); Laboratoire d' Etude des Microstructures - ONERA/CNRS, UMR 104, B.P. 72, 92322 Chatillon (France); Ricolleau, C. [Laboratoire Materiaux et Phenomenes Quantiques, Universite Paris 7/CNRS, UMR 7162, 2 Place Jussieu, 75251 Paris (France); Oikawa, T. [Laboratoire Materiaux et Phenomenes Quantiques, Universite Paris 7/CNRS, UMR 7162, 2 Place Jussieu, 75251 Paris (France); JEOL (Europe) SAS, Espace Claude Monet, 1 Allee de Giverny, 78290 Croissy-sur-Seine (France); Langlois, C. [Laboratoire Materiaux et Phenomenes Quantiques, Universite Paris 7/CNRS, UMR 7162, 2 Place Jussieu, 75251 Paris (France); Le Bouar, Y.; Loiseau, A. [Laboratoire d' Etude des Microstructures - ONERA/CNRS, UMR 104, B.P. 72, 92322 Chatillon (France)

2009-06-15

Nanoparticles' morphology is a key parameter in the understanding of their thermodynamical, optical, magnetic and catalytic properties. In general, nanoparticles, observed in transmission electron microscopy (TEM), are viewed in projection so that the determination of their thickness (along the projection direction) with respect to their projected lateral size is highly questionable. To date, the widely used methods to measure nanoparticles thickness in a transmission electron microscope are to use cross-section images or focal series in high-resolution transmission electron microscopy imaging (HRTEM 'slicing'). In this paper, we compare the focal series method with the electron tomography method to show that both techniques yield similar particle thickness in a range of size from 1 to 5 nm, but the electron tomography method provides better statistics since more particles can be analyzed at one time. For this purpose, we have compared, on the same samples, the nanoparticles thickness measurements obtained from focal series with the ones determined from cross-section profiles of tomograms (tomogram slicing) perpendicular to the plane of the substrate supporting the nanoparticles. The methodology is finally applied to the comparison of CoPt nanoparticles annealed ex situ at two different temperatures to illustrate the accuracy of the techniques in detecting small particle thickness changes.

Temperature dependences in electron-stimulated desorption of neutral europium

CERN Document Server

Ageev, V N; Madey, T E

2003-01-01

The electron-stimulated desorption (ESD) yield for neutral europium (Eu) atoms from Eu layers adsorbed on oxygen-covered tungsten surfaces has been measured as a function of electron energy, europium coverage and degree of oxidation of tungsten, with an emphasis on effects of substrate temperature. The measurements have been carried out using a time-of-flight method and surface ionization detector. We expand on an earlier report, and compare ESD of multivalent Eu with ESD of monovalent alkali atoms, studied previously. The Eu atom ESD is a complicated function of Eu coverage, electron energy and substrate temperature. In the coverage range 0.05-0.35 monolayer (ML), overlapping resonant-like Eu atom yield peaks are observed at electron energies E sub e of 36 and 41 eV that might be associated with Eu or W shallow core level excitations. Additional resonant-like peaks are seen at E sub e of 54 and 84 eV that are associated with W 5p and 5s level excitations. The Eu atom yield peaks at 36 and 41 eV are seen only...

Comparison test of electronic dosemeters

International Nuclear Information System (INIS)

Butterweck, G.; Zimmerli, H.P.; Wernli, C.

2001-01-01

To assist with a planned purchase of electronic dosemeters by the Swiss Federal Office for Civil Protection, the calibration laboratory of the Paul Scherrer Institute performed tests on 11 types of electronic dosemeters manufactured by 10 European and American companies. The technical specifications for the World Trade Organisation (WTO) tendering procedure were largely in accord with the specifications of the international standard IEC 61526. First tests were performed with samples from each type of dosemeter. The reproducibility of a dose of 0.1 mSv generated with 137 Cs radiation at a dose rate of 2.1 mSv.h -1 was found adequate for all tested dosemeter types. The response for environmental levels of radiation showed a large variation, indicating insufficient background correction of some dosemeters. A very high dose rate of 10 Sv.h -1 provoked faulty dose readings for more than half of the tested dosemeters. Dosemeter response for low-energy photon radiation was satisfactory for two of the tested dosemeter types. Four dosemeter types were selected for extended technical tests. Three samples of each of these dosemeter types were purchased. For drop and temperature tests the specifications of the WTO tendering procedure outranged the specification of the IEC standard. Whereas even at a temperature of -25 deg. C the tested dosemeters functioned normally, drops from a height of 2 m onto a wooden surface rendered the samples of two dosemeter types inoperative. (author)

Projectile Coulomb center effects on low-energy electron emission from H[sup +][yields]Ne collisions

Energy Technology Data Exchange (ETDEWEB)

Suarez, S. (Centro Atomico Bariloche e Inst. Balseiro, Comision Nacional de Energia Atomica, S.C. de Bariloche, Rio Negro (Argentina)); Garibotti, C. (Centro Atomico Bariloche e Inst. Balseiro, Comision Nacional de Energia Atomica, S.C. de Bariloche, Rio Negro (Argentina) Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)); Bernardi, G. (Centro Atomico Bariloche e Inst. Balseiro, Comision Nacional de Energia Atomica, S.C. de Bariloche, Rio Negro (Argentina) Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)); Focke, P. (Centro Atomico Bariloche e Inst. Balseiro, Comision Nacional de Energia Atomica, S.C. de Bariloche, Rio Negro (Argentina)); Meckbach, W. (Centro Atomico Bariloche e Inst. Balseiro, Comision Nacional de Energia Atomica, S.C. de Bariloche, Rio Negro (Argentina) Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina))

1994-03-01

We present doubly differential energy distributions of low-energy electrons emitted in collisions of 106 keV H[sup +] on Ne atoms. We find a relevant dependence of the measured distribution of low-energy electrons on the physical extension of the gas target and discuss a correction procedure. Our measurements enable a quantitative analysis of the shape of the soft electron peak, which is clearly evidenced by measured contour lines. Present results indicate that ''two center effects'' must be considered in order to account for the strong asymmetry of the soft electron peak observed experimentaly. (orig.)

Vibrational and electronic excitation of hexatriacontane thin films by low energy electron impact

International Nuclear Information System (INIS)

Vilar, M.R.; Schott, M.; Pfluger, P.

1990-01-01

Thin polycrystalline films of hexatriacontane (HTC) were irradiated with low energy (E=0.5--15 eV) electrons, and off-specular backscattered electron spectra were measured. Below E∼7 eV, single and multiple vibrational excitations only are observed, which relax the electrons down to the bottom of the HTC conduction band. Due to the negative electron affinity of HTC, thermal electrons are emitted into vacuum. Structure in the backscattered electron current at kinetic energies about 1.5 and 4 eV are associated to conduction band density of states. Above E∼7 eV, the dominant losses correspond to electronic excitations, excitons, or above a threshold (energy of the electron inside the HTC film) at 9.2±0.1 eV, electron--hole pair generation. The latter process is very efficient and reaches a yield of the order of one ∼11 eV. Evidence for chemical reaction above E∼4 eV is observed

Electron transport in gold colloidal nanoparticle-based strain gauges

Science.gov (United States)

Moreira, Helena; Grisolia, Jérémie; Sangeetha, Neralagatta M.; Decorde, Nicolas; Farcau, Cosmin; Viallet, Benoit; Chen, Ke; Viau, Guillaume; Ressier, Laurence

2013-03-01

A systematic approach for understanding the electron transport mechanisms in resistive strain gauges based on assemblies of gold colloidal nanoparticles (NPs) protected by organic ligands is described. The strain gauges were fabricated from parallel micrometer wide wires made of 14 nm gold (Au) colloidal NPs on polyethylene terephthalate substrates, elaborated by convective self-assembly. Electron transport in such devices occurs by inter-particle electron tunneling through the tunnel barrier imposed by the organic ligands protecting the NPs. This tunnel barrier was varied by changing the nature of organic ligands coating the nanoparticles: citrate (CIT), phosphines (BSPP, TDSP) and thiols (MPA, MUDA). Electro-mechanical tests indicate that only the gold NPs protected by phosphine and thiol ligands yield high gauge sensitivity. Temperature-dependent resistance measurements are explained using the ‘regular island array model’ that extracts transport parameters, i.e., the tunneling decay constant β and the Coulomb charging energy EC. This reveals that the Au@CIT nanoparticle assemblies exhibit a behavior characteristic of a strong-coupling regime, whereas those of Au@BSPP, Au@TDSP, Au@MPA and Au@MUDA nanoparticles manifest a weak-coupling regime. A comparison of the parameters extracted from the two methods indicates that the most sensitive gauges in the weak-coupling regime feature the highest β. Moreover, the EC values of these 14 nm NPs cannot be neglected in determining the β values.

Dissociative electron attachment to methylhalides in 3-methylhexane glassy matrix

International Nuclear Information System (INIS)

Harada, K.; Irie, M.; Yoshida, H.

1976-01-01

Dissociative electron attachment reaction to CH 3 I, CH 3 Cl and CH 3 F in a 3-methylhexane glassy matrix was studied by determining the yield of trapped electrons and that of methyl radicals immediately after γ irradiation at 77 K as a function of the scavenger concentration. The efficiency of conversion from the trapped electrons to the methyl radicals was also studied by photobleaching the trapped electrons. The results obtained are (1) the dissociative electron attachment occurs to CH 3 F, for which the gas phase data indicate that the reaction is endothermic by 1.2 eV, during either the γ irradiation or the photobleaching, and (2) CH 3 F is relatively less efficient in scavenging photo-liberated electrons than in scavenging the electrons during the γ irradiation, whereas CH 3 I and CH 3 Cl are efficient scavengers for both the electrons. The dependence of the yields of the trapped electrons and the methyl radicals is discussed in terms of the electron-tunnelling mechanism and the epithermal electron-scavenging mechanism. (author)

States of the electron in hydrocarbon liquids

International Nuclear Information System (INIS)

Mozumder, A.

2005-01-01

Some features of the stationary and dynamic states of the electron are critically examined. Outline of a quantum mechanical description of electron thermalization is attempted qualitatively. The effects of both the mean free path and the reaction inefficiency on electron-ion geminate escape probability are investigated by a recently developed Metropolis method. The trapped state is interpreted in terms of Anderson localization, yielding an approximate number of molecules interacting with the trapped electron

Monte Carlo calculation of secondary electron emission from carbon-surface by obliquely incident particles

International Nuclear Information System (INIS)

Ohya, Kaoru; Kawata, Jun; Mori, Ichiro

1990-01-01

Incidence angle dependences of secondary electron emission from a carbon surface by low energy electron and hydrogen atom are calculated using Monte Carlo simulations on the kinetic emission model. The calculation shows very small increase or rather decrease of the secondary electron yield with oblique incidence. It is explained in terms of not only multiple elastic collisions of incident particles with the carbon atoms but also small penetration depth of the particles comparable with the escape depth of secondary electrons. In addition, the two types of secondary electron emission are distinguished by using the secondary electron yield statistics; one is the emission due to trapped particles in the carbon, and the other is that due to backscattered particles. The high-yield component of the statistics on oblique incidence is more suppressed than those on normal incidence. (author)

Model Identification and FE Simulations: Effect of Different Yield Loci and Hardening Laws in Sheet Forming

International Nuclear Information System (INIS)

Flores, P.; Lelotte, T.; Bouffioux, C.; El Houdaigui, F.; Habraken, A.M.; Duchene, L.; Bael, A. van; He, S.; Duflou, J.

2005-01-01

The bi-axial experimental equipment developed by Flores enables to perform Baushinger shear tests and successive or simultaneous simple shear tests and plane-strain tests. Such experiments and classical tensile tests investigate the material behavior in order to identify the yield locus and the hardening models. With tests performed on two steel grades, the methods applied to identify classical yield surfaces such as Hill or Hosford ones as well as isotropic Swift type hardening or kinematic Armstrong-Frederick hardening models are explained. Comparison with the Taylor-Bishop-Hill yield locus is also provided. The effect of both yield locus and hardening model choice will be presented for two applications: Single Point Incremental Forming (SPIF) and a cup deep drawing

Model Identification and FE Simulations: Effect of Different Yield Loci and Hardening Laws in Sheet Forming

Science.gov (United States)

Flores, P.; Duchêne, L.; Lelotte, T.; Bouffioux, C.; El Houdaigui, F.; Van Bael, A.; He, S.; Duflou, J.; Habraken, A. M.

2005-08-01

The bi-axial experimental equipment developed by Flores enables to perform Baushinger shear tests and successive or simultaneous simple shear tests and plane-strain tests. Such experiments and classical tensile tests investigate the material behavior in order to identify the yield locus and the hardening models. With tests performed on two steel grades, the methods applied to identify classical yield surfaces such as Hill or Hosford ones as well as isotropic Swift type hardening or kinematic Armstrong-Frederick hardening models are explained. Comparison with the Taylor-Bishop-Hill yield locus is also provided. The effect of both yield locus and hardening model choice will be presented for two applications: Single Point Incremental Forming (SPIF) and a cup deep drawing.

Grain yield losses in yellow-rusted durum wheat estimated using digital and conventional parameters under field conditions

Directory of Open Access Journals (Sweden)

Omar Vergara-Diaz

2015-06-01

Full Text Available The biotrophic fungus Puccinia striiformis f. sp. tritici is the causal agent of the yellow rust in wheat. Between the years 2010–2013 a new strain of this pathogen (Warrior/Ambition, against which the present cultivated wheat varieties have no resistance, appeared and spread rapidly. It threatens cereal production in most of Europe. The search for sources of resistance to this strain is proposed as the most efficient and safe solution to ensure high grain production. This will be helped by the development of high performance and low cost techniques for field phenotyping. In this study we analyzed vegetation indices in the Red, Green, Blue (RGB images of crop canopies under field conditions. We evaluated their accuracy in predicting grain yield and assessing disease severity in comparison to other field measurements including the Normalized Difference Vegetation Index (NDVI, leaf chlorophyll content, stomatal conductance, and canopy temperature. We also discuss yield components and agronomic parameters in relation to grain yield and disease severity. RGB-based indices proved to be accurate predictors of grain yield and grain yield losses associated with yellow rust (R2 = 0.581 and R2 = 0.536, respectively, far surpassing the predictive ability of NDVI (R2 = 0.118 and R2 = 0.128, respectively. In comparison to potential yield, we found the presence of disease to be correlated with reductions in the number of grains per spike, grains per square meter, kernel weight and harvest index. Grain yield losses in the presence of yellow rust were also greater in later heading varieties. The combination of RGB-based indices and days to heading together explained 70.9% of the variability in grain yield and 62.7% of the yield losses.

Syringe-injectable electronics.

Science.gov (United States)

Liu, Jia; Fu, Tian-Ming; Cheng, Zengguang; Hong, Guosong; Zhou, Tao; Jin, Lihua; Duvvuri, Madhavi; Jiang, Zhe; Kruskal, Peter; Xie, Chong; Suo, Zhigang; Fang, Ying; Lieber, Charles M

2015-07-01

Seamless and minimally invasive three-dimensional interpenetration of electronics within artificial or natural structures could allow for continuous monitoring and manipulation of their properties. Flexible electronics provide a means for conforming electronics to non-planar surfaces, yet targeted delivery of flexible electronics to internal regions remains difficult. Here, we overcome this challenge by demonstrating the syringe injection (and subsequent unfolding) of sub-micrometre-thick, centimetre-scale macroporous mesh electronics through needles with a diameter as small as 100 μm. Our results show that electronic components can be injected into man-made and biological cavities, as well as dense gels and tissue, with >90% device yield. We demonstrate several applications of syringe-injectable electronics as a general approach for interpenetrating flexible electronics with three-dimensional structures, including (1) monitoring internal mechanical strains in polymer cavities, (2) tight integration and low chronic immunoreactivity with several distinct regions of the brain, and (3) in vivo multiplexed neural recording. Moreover, syringe injection enables the delivery of flexible electronics through a rigid shell, the delivery of large-volume flexible electronics that can fill internal cavities, and co-injection of electronics with other materials into host structures, opening up unique applications for flexible electronics.

Observation of second harmonics in laser-electron scattering using low energy electron beam

Energy Technology Data Exchange (ETDEWEB)

Iinuma, Masataka [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan)]. E-mail: iinuma@hiroshima-u.ac.jp; Matsukado, Koji [Venture Business Laboratory, Hiroshima University, 1-313 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527 (Japan); Endo, Ichita [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Hashida, Masaki [Institute for chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Hayashi, Kenji [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Kohara, Akitsugu [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Matsumoto, Fumihiko [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Nakanishi, Yoshitaka [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Sakabe, Shuji [Institute for chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Shimizu, Seiji [Institute for chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Tauchi, Toshiaki [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Yamamoto, Ken [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan); Takahashi, Tohru [ADSM, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530 (Japan)

2005-10-17

We observed photon generation in the second harmonic region in collisions of 10 keV free electrons and the intense laser beam with the peak intensity of 4.0x10{sup 15} W/cm{sup 2}. Observed photon yield was 3 orders of magnitude higher than expectation from the nonlinear Compton scattering. The observation indicates necessity of further investigation for the interaction between the intense laser field and the low energy electron beam.

Analytical local electron-electron interaction model potentials for atoms

International Nuclear Information System (INIS)

Neugebauer, Johannes; Reiher, Markus; Hinze, Juergen

2002-01-01

Analytical local potentials for modeling the electron-electron interaction in an atom reduce significantly the computational effort in electronic structure calculations. The development of such potentials has a long history, but some promising ideas have not yet been taken into account for further improvements. We determine a local electron-electron interaction potential akin to those suggested by Green et al. [Phys. Rev. 184, 1 (1969)], which are widely used in atom-ion scattering calculations, electron-capture processes, and electronic structure calculations. Generalized Yukawa-type model potentials are introduced. This leads, however, to shell-dependent local potentials, because the origin behavior of such potentials is different for different shells as has been explicated analytically [J. Neugebauer, M. Reiher, and J. Hinze, Phys. Rev. A 65, 032518 (2002)]. It is found that the parameters that characterize these local potentials can be interpolated and extrapolated reliably for different nuclear charges and different numbers of electrons. The analytical behavior of the corresponding localized Hartree-Fock potentials at the origin and at long distances is utilized in order to reduce the number of fit parameters. It turns out that the shell-dependent form of Green's potential, which we also derive, yields results of comparable accuracy using only one shell-dependent parameter

Contrasting response of biomass and grain yield to severe drought in Cappelle Desprez and Plainsman V wheat cultivars

Directory of Open Access Journals (Sweden)

Kenny Paul