Japan Atomic Energy Research Institute (JAERI) and the High Energy Accelerator Research Organization (KEK) are promoting the joint project integrating both the Neutron Science Project (NSP) of JAERI and the Japan Hadron Facility Project (JHF) of KEK for comprehensive studies on basic science and technology using high-intensity proton accelerator. This document describes the joint project prepared by the Joint Project Team of JAERI and KEK to construct accelerators and research facilities necessary both for the NSP and the JHF at the site of JAERI Tokai Establishment. It was originally written in English and translated into Japanese with some corrections. (author)
Charge-charge interactions dramatically influence the dissociation and proton transfer reactivity of large multiply protonated ions. In combination with tandem mass spectrometry, proton transfer...Full Text Available
Several compact proton accelerator systems for use in proton therapy have recently been proposed. Of paramount importance to the development of such an accelerator system is the maximum kinetic energy...Full Text Available
The effects of orthovanadate on the uptake of sucrose by Ricinus cotyledons and on sucrose-coupled proton influx were measured in order to gain insight into the relationship to the plasma membrane proton pump. Vanadate had no effect on short-term sucrose uptake. In long-term experiments (> 30 min) sucrose uptake was progressively inhibited, but only at high external sucrose concentrations. Vanadate did not affect proton efflux pumping in the absence of sucrose and neither did it change the initial rate of sucrose-coupled proton influx. However, it enhanced the maximal level of sucrose-induced alkalization of the medium at all sucrose concentrations tested. This is interpreted as an inhibiting effect of vanadate on the proton pump that recycles protons during sucrose-proton cotransport. The sensitivity towards vanadate indicates that this ...
The recent measurements by the BES Collaboration of J/psi decays into a photon and a proton-antiproton pair indicate a strong enhancement at the proton-antiproton threshold not observed in the decays into a neutral pion and a proton-antiproton pair. Is this enhancement due to a proton-antiproton quasi-bound state or a baryonium? A natural explanation follows from a traditional model of proton-antiproton interactions based on G-parity transformation. The observed proton-antiproton structure is due to a strong attraction in the 1S0 state, and possibly to a near-threshold quasi-bound state in the 11S0 wave.
We will examine modeling data for various orbits using modeling software and compare this with actual satellite flight result. In particular, we will discuss the contributions of trapped protons to total dose and the effectiveness of shielding.
The main subject of this thesis is the study of the hardronic final state in deep-inelastic electron-proton scattering. Theexperiment described in this thesis is performed with such a high resolution that the substructure of the proton is probed by the electron beam with a resolution of less than 10{sup -15} cm. (orig./HSI).
A balanced application of chemiosmosis to plant mitochondria is presented. Electron transport carriers are sequenced to achieve proton translocation across the inner membrane. The processes of proton translocation, use, and release are integrated to yield a description of the effective proton gradient available for metabolite transport and ATP synthesis. 27 references, 6 figures.
Cross section parameterizations for antiproton production in pp collisions are used to predict the antiproton/proton ratio resulting from a flux of cosmic protons with energy spectral index of 2.6 interacting with a 5 gm/cm/sup 2/ column density of H. (GHT)
The design of the absorber blocks for internal and external dumping of the SPS proton beam is discussed. In addition, the external target stations for slow and fast extracted proton beams are described.
The authors present some recent measurements on electroweak physics using data collected by the CDF experiment at the Tevatron proton anti-proton collider ({radical}s = 1.96 TeV) at Fermilab.
PurposeTo determine the dosimetric impact of inter-fraction anatomical movements in prostate cancer patients receiving proton therapy.Full Text Available
Background"Nubiotics" are synthetic oligonucleotides and nucleotides with nuclease-resistant backbones, and are fully protonated for enhanced ability to be taken up by bacterial...Full Text Available
We discuss the consequence of local duality for elastic scattering, and derive a model-independent equation between structure functions at x ? 1 and elastic electromagnetic form factors. Then the electromagnetic form factors of proton are discussed using the quark-hadron duality theory. We also debate the form factor of proton in a bound state. It may be an effective approach to study the form factor of proton in media.
The cross sections for proton-proton elastic scattering at Fermilab and ISR energies are investigated in the framework of the multiple constituent scattering formalism, including the contributions of the inelastic intermediate states. We find that the higher-order multiple scattering amplitudes are strongly suppressed due to the presence of the inelastic intermediate states. The calculated cross sections reproduce the high energy experimental data fairly well. (author).
Using ab initio (SCF/6-31G) method, mechanisms of proton migrations in methaboric acid dimers have studied. It is shown that in all the dimers considered a cooperative transfer of protons occurs. The calculated values of activation barriers of cooperative proton transfer reactions in the dimers are equal to 28.6 kcal/mol.
In earliest works devoted to proton computed tomography it was shown that the advantage of pCT image reconstruction appears when the energy is close to the Bragg peak region, since the proton passes the object. This effect provided by the Bragg peak makes the computerized tomography with protons possible. However, when decreasing the initial proton energy, with the increase of the irradiation dose, there are two effects that work simultaneously in opposite ways. First, the energy loss of a proton in an object becomes bigger at small initial energy. At the same time decreasing of the proton energy results in the increase of the energy straggling, requiring a larger number of protons. In this work the radiation dose dependence on the proton initial energy was studied using analytical formulas and computer simulations. The ...
In order to improve the measuring efficiency, a 'proton-gamma' coincidence technique in combination with a He-jet tape transport system was proposed and employed to identify the #beta#-delayed proton precursors. The study of #beta#-delayed proton decays near the proton drip line by using the 'proton-gamma' coincidence technique over the last 5 years at the Institute of Modern Physics, Lanzhou, China, was summarized. New #beta#-delayed proton precursors "1"2"1Ce, "1"2"5Nd, "1"2"8Pm, "1"2"9Sm, "1"3"5Gd, "1"3"7Gd, "1"3"9Dy, "1"4"2Ho, and "1"4"9Yb in the rare-earth region along a speculated proton drip line were synthesized and identified for the first time. The #beta#-delayed proton decays of "8"1Zr, "8"5Mo, "8"9Ru, and "9"3Pd in T_z=1/2 series as well as "9"2Rh in T_z=1 series were observed.
In this article, we investigate the "naive non-abelianization" (NNA) contributions of the higher-twist Feynman diagrams to the large-$p_T$ inclusive pion production cross section in proton-proton collisions and present the general formulae for the higher-twist differential cross sections in the case of the running coupling and frozen coupling approaches. We compared the resummed "naive non-abelianization" higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section. The structure of infrared renormalon singularities of the higher twist subprocess cross section and it's resummed expression (the Borel sum) are found. It is shown that the resummed result depends on the choice of the meson wave functions used in the calculations. We discuss the phenomenological consequences of possible higher-twist contributions to the meson production in proton-proton collisions in within NNA ...
Spin-lattice relaxation rates of protein and water protons in dry and hydrated immobilized bovine serum albumin were measured in the range of 1H Larmor frequency from 10 kHz to 30...Full Text Available
Calculations of dose per monitor unit (D∕MU) are required in addition to measurements to increase patient safety in the clinical practice of proton radiotherapy. As in conventional photon and...Full Text Available
Proton and neutron transfer populating low-lying states have been studied in the system {sup 144}Sm+{sup 88}Sr at an energy below the Coulomb barrier. The experimental cross sections for the single proton transfer are well reproduced by DWBA-calculations using spectroscopic information from light ion reactions. The two-proton transfer appears enhanced relative to the uncorrelated sequential transfer of single protons. The same holds for the transfer of proton pairs, the enhancement is kept for the second pair. This is interpreted as a supercurrent between two superfluid nuclear proton-pair wave functions: More mass and charge is transported per time unit in pairs than by single nucleons. Neutron transfer is observed with large cross sections and is found to contribute to the energy loss observed in the transfer reactions. For mixed ...
Proton and neutron transfer populating low-lying states have been studied in the system "1"4"4Sm+"8"8Sr at an energy below the Coulomb barrier. The experimental cross sections for the single proton transfer are well reproduced by DWBA-calculations using spectroscopic information from light ion reactions. The two-proton transfer appears enhanced relative to the uncorrelated sequential transfer of single protons. The same holds for the transfer of proton pairs, the enhancement is kept for the second pair. This is interpreted as a supercurrent between two superfluid nuclear proton-pair wave functions: More mass and charge is transported per time unit in pairs than by single nucleons. Neutron transfer is observed with large cross sections and is found to contribute to the energy loss observed in the transfer reactions. For mixed proton-neutron ...
The measured result of charged multiplicity in cosmic-ray proton induced nuclear reaction from Chinese satellite emulsion is reported. The correlation of shower and heavy particles is discussed and compared with p-emulsion interactions.
Peptic ulcer bleeding is a common disease and recurrent bleeding is an independent risk factor of mortality. Infusion with proton pump inhibitors (PPIs) prevents recurrent bleeding after successful...Full Text Available
Homologous to bacteriorhodopsin and even more to proteorhodopsin, xanthorhodopsin is a light-driven proton pump that, in addition to retinal, contains a noncovalently bound carotenoid with a function...Full Text Available
The data are analyzed on cumulative antiproton production on Be, Al, Cu, and Ta nuclei induced by 10 GeV protons. The analysis is carried out in the framework of the flucton quark fragmentation model.
Depending on their unique physical properties, proton and heavy ions have taken an irreplaceable role in modern means of tumor treatment. One-step process and two-step process physical models were employed to explain the mechanism of ion energy loss. The transport process of proton and "1"2C in water was simulated by Geant4 toolkit to study the physical properties of ion beam. The calculation results were discussed, which showed the advantages and disadvantages of proton and "1"2C in the medical application. (authors)
Proton production in pA interactions in the kinematically forbidden region is studied using the intranuclear cascade model for the primary proton energies 7.5 and 8.9 GeV/c. The region of secondary-proton kinetic energies above 100 MeV, where the contribution from the post-cascade stages of the interaction is small, is studied. The calculated energy and angular spectra are in good agreement with the experimental ones. The mechanisms of multiple rescattering of particles on the nucleons of the nucleus and ..pi..-meson absorption on a two-nucleon flucton are analyzed. The kinematical ranges where these mechanisms operate are determined.
At the conclusion of polarized proton commissioning in February 1986, protons with an average polarization of 45%, momentum of 21.7 GeV/c, and intensity of 2 x 10/sup 10/ protons per pulse, were extracted to an external polarimeter at the Brookhaven AGS. In order to maintain this polarization, five intrinsic and nearly forty imperfection depolarizing resonances had to be corrected. An apparent interaction between imperfection and intrinsic resonances occurring at very nearly the same energy was observed and the correction of imperfection resonances using ''beat'' magnetic harmonics discovered in the previous AGS commissioning run was further confirmed.
Techniques for studying nuclear structure are reviewed. Examples are given of charge density determinations by electron and proton inelastic scattering. (AIP)
No magnetic monopoles were found in 2.5*10/sup 18/ primary proton- aluminium interactions produced by exposing an aluminium target to the Fermilab 300 GeV/c proton beam. Negative searches have also resulted from exposures of material to electrons at SLAC and from pp interactions at the CERN-ISR. The monopole pair production probability in proton-nucleon collisions is shown to be of order 10/sup -18/ or less, with 95% confidence level, if monopoles have masses less than 12 GeV. (24 refs).
In Korea, the Proton Engineering Frontier Project (PEFP) is building a proton linear accelerator facility with energy up to 100MeV and a beam current of 20mA. In this study, a radiation field after shutdown in the accelerator facility of the PEFP was evaluated for the purpose of the radiation shielding by using MCNPX code. A facility modeling was performed for the accelerator tunnel building, accelerator chain, target rooms and beam experiment hall. And radiation source terms were evaluated in the facility. With this facility, model and radiation source terms, the concentration of 41Ar was evaluated and the cooling time satisfying regulation in Korea was calculated.
The emission of light charged particles from heavy fragments of uranium fission induced by 153-MeV protons is studied. The probability of their emission is 2.7 x 10{sup - 2} per fission event. It is found that these particles affect the distribution of angles of fragment divergence and the angular distribution of heavy fragments with respect to the primary-proton beam. Experimental results suggest that the preequilibrium emission of particles is correlated with fission. Two mechanisms of interaction between 153-MeV protons and uranium nuclei are considered. 13 refs., 10 figs., 1 tab.
This book explores the development, present, and future applications of proton microprobes in the micrometer range. Among the topics discussed: the use of proton beams for analytical purposes; techniques of focusing or collimating ion beams; improving and measuring beam spots; the analytical capabilities of the nuclear microprobe in comparison to other micro techniques; and applications and results by several internationally known microprobe laboratories.
The NuMI beam at Fermilab has delivered over 5 x 10{sup 20} 120 GeV protons to the neutrino production target since the start for MINOS [1] neutrino oscillation experiment operation in 2005. We report on proton beam commissioning and operation status, including successes and challenges with this beam.
An internuclear cascade-evaporation code is used to model energy deposition in thin slabs of silicon. This model shows that protons produce a significant number of events with effective Linear Energy Transfer (LET) greater than 8 MeV cm"2/mg and demonstrates that proton testing of microelectronic components can be an effective way to screen devices for low earth orbit susceptibility to heavy ions.
Radiation therapy has shown definite technical improvement due to application of proton beam irradiation. Clinical results of proton beam therapy also suggested enlargement of indication ranges in radial treatment and decrease of post radiation damages of the treatment of cancers in deep-seated organs. Inprovement of result in cancer therapy could be expected by this treatment technique in the future.
Production of lead-203 by proton irradiation of bismuth metal has been investigated as a replacement method for commercially available lead-203. Targets of bismuth metal (0.1 cm thick) were irradiated for periods of 1-3 hours with 90 MeV protons. After processing of the target, the estimated yield of lead-2-3 was 30 millicuries/microamp.
Isospin-breaking effects in the baryonic sector are studied in the framework of a medium-modified Skyrme model. The neutron-proton mass difference in infinite, asymmetric nuclear matter is discussed. In order to describe the influence of the nuclear environment on the skyrmions, we include energy-dependent charged and neutral pion optical potentials in the s- and p-wave channels. The present approach predicts that the neutron-proton mass difference is mainly dictated by its strong part and that it strongly decreases in neutron matter. (orig.)
Depth dose distributions for protons in the energy range from 2 to 600 MeV have been calculated by Monte Carlo and analytical methods. The dependence on energy of Maximum Dose Equivalent (MDE), quality factor and isotropic factor recommended for practical use are presented. The problems connected with regulation of maximum permissible proton fluxes are discussed. (author).
A large set of data on proton-proton differential cross sections, analyzing powers and the double-polarization parameter A{sub NN} is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3GeV/c to 50GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the {rho}, {omega}, f{sub 2}, and a{sub 2} trajectories and single-Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model. (orig.)
TiH{sub 2} and TiD{sub 2} thick targets were bombarded with 100 to 200 keV protons. Evidence for nuclear reactions was obtained by means of a surface barrier particle detector. Proton irradiation of TiD{sub 2} produced the following observations: {alpha} particle emission identified as (p, {alpha}) reactions from {sup 11}B and {sup 7}Li impurities in the target at ppm concentrations; and {approx}3 MeV proton and {approx}1 MeV triton emission from secondary D-D reactions caused by elastic scattering of the primary proton with a target deuteron. A 3.9 MeV {alpha} particle peak measured by others was not observed. (author)
Lifetime observations on a group of 358 rhesus monkeys indicate that life expectancy loss from exposure to protons in the energy range encountered in the Van Allen belts and solar proton events is influenced primarily by the dose rather than the energy of radiation. After 24 years, life expectancy losses from similar surface doses of low-LET (138-2300 MeV) and high-LET (32-55 MeV) protons are not significantly different, but the high-LET protons are associated with more deaths in the early years, while the low-LET protons contribute more to mortality in later years. In males, the most significant cause of life shortening is nonleukemia cancers.
The determination of ratio of neutron over proton matrix elements by inelastic proton scattering, for 0{sup +}{yields}2{sup +} transitions, is investigated via the comparison between experimental data and theoretical calculations. Calculations into the context of a macroscopic and a microscopic description are performed for a wide mass range nuclei: {sup 18}O, {sup 30}Si, {sup 32,34}S, {sup 48}Ca, {sup 88}Sr, for which these ratios were determined previously with an independent technique. At that point the choice of the theoretical model may be very critical. It is thus the purpose of this investigation to point out the most suitable model. It is found that in general both theoretical models can be employed for the reliable determination of neutron over proton matrix element ratios.
The determination of ratio of neutron over proton matrix elements by inelastic proton scattering, for 0"+#->#2"+ transitions, is investigated via the comparison between experimental data and theoretical calculations. Calculations into the context of a macroscopic and a microscopic description are performed for a wide mass range nuclei: "1"8O, "3"0Si, "3"2","3"4S, "4"8Ca, "8"8Sr, for which these ratios were determined previously with an independent technique. At that point the choice of the theoretical model may be very critical. It is thus the purpose of this investigation to point out the most suitable model. It is found that in general both theoretical models can be employed for the reliable determination of neutron over proton matrix element ratios.
The portion of the potential energy surface (PES) of acetylacetone relevant for the intramolecular proton transfer reaction is studied using ab initio and DFT methods. The best estimate of the barrier governing proton transfer was found to be 3.4 kcal mol{sup -1} at the MP4(FC)/6-311 + G(2d,2p)//MP2(FC)/6-311 + G(2d,2p) level of theory. Six stationary points on the PES were characterized as well as the reaction paths connecting these points. Special attention paid to the pathway of intramolecular proton transfer reveals that the internal rotation of the methyl group adjacent to the carbonyl group and the proton transfer reaction are consecutive processes.
The LAHET code system calculations and experimental results for proton interactions with an energy <50 MeV are compared. For these energies, the theories behind the LAHET models are not applicable. Three quantities compared are (a) the magnitude of the neutron yield generated through proton interactions, (b) the energy and angular distributions of the resultant neutrons, and (c) the residual nuclei produced by proton interactions (spallation products). The comparisons are for protons incident on iron and copper, except in the case of the energy and angular distributions, which are calculated only for iron. The neutron yields predicted by LAHET agree with published measurements to within 50% for both materials. For iron, the predicted energy and angular distributions agree to within a factor of 3. Finally, the predicted spallation product yields of both materials agree with measurements to within a ...
For charged particle irradiations, the response of an imaging plate (IP) changes around the Bragg peak. Therefore, an appropriate compensation is necessary for the evaluation of dose distribution formed by charged particles such as protons. In this paper, the response of IPs to clinical proton beams is investigated. An experimentally-obtained depth-dose distribution (an ordinary Bragg curve) by a silicon semiconductor detector (SSD) is employed to evaluate the compensation factors as a function of proton penetrating depth, i.e. residual range. A typical dose distribution in a water phantom formed by an L-shaped bolus is measured by IPs and corrected by using the information of those compensation factors; the residual proton range is successfully calculated by the pencil beam algorithm at an arbitrary point. The results show a good agreement with the measurements by the SSD within the rms error of 3.0%.
The proton beam has a unique advantage over the electron and photon beams in that it can give very high radiation dose to the tumor volume, while effectively sparing the neighboring healthy tissue and organs. For the clinical application of the proton beam, it is very important to confirm the location of the proton beam in the patient, preferentially during the treatment. It has been suggested that the range of the proton beam in the patient can be determined by measuring prompt gammas from the proton beam passage. Recently, a prototype prompt-gamma scanning system has been constructed and tested using experimental and therapeutic proton beams. The measurement results for the proton beams of 70 . 230 MeV showed that a clear correlation exists between the distribution of the prompt gammas and the proton beam range. The ...
An attempt to determine lysozyme hydration by employing a proton nuclear magnetic resonance (NMR) spin-echo technique and to correlated such measurements with the 20 "0C sorption equilibrium data is made. Determinations of specific site hydration for lysozyme, as well as proton NMR transverse relaxation rates for five different types of water populations in the lysozyme-water system, are presented over the whole range of lysozyme concentrations. The proton spin-echo NMR results are consistent with a three-component analysis of the sorption isotherm up to 70% water content, above which two additional water populations are identified by 360-MHz proton NMR spin-echoes. On the basis of the proton NMR results, a major component (III) of the lysozyme sorption isotherm is assigned to the water trapped between lysozyem molecules, whose relaxation rate is increased by diffusion barriers. The ...
W and Z bosons are expected to be produced abundantly at the Large Hadron Collider (LHC). This large dataset and the high LHC energy will allow for detailed studies of their properties in a previously unexplored kinematic domain of low parton momentum fraction and high energy scale thus providing, together with the proton-proton nature of the collisions, new constraints on the parton distribution functions and precise tests of perturbative QCD. First determinations of the W -> lnu and Z -> ll (l = e,mu) production cross sections for proton-proton collisions at sqrt(s) = 7 TeV were performed using about 320/nb of data recorded by the ATLAS experiment at the LHC. The results of these measurements for W and Z bosons for proton-proton collisions at sqrt(s) = 7 TeV are presented. In addition ?rst measurements of the ratio between the W and Z/gamma*-cross sections and of the W -> lnu charge asymmetry are also ...
We have performed a detailed analysis of water clustering and percolation in hydrated Nafion configurations generated by classical molecular dynamics simulations. Our results show that at low hydration levels H2O molecules are isolated and a continuous hydrogen-bonded network forms as the hydration level is increased. Our quantitative analysis has established a hydration level (?) between 5 and 6 H2O/SO3- as the percolation threshold of Nafion. We have also examined the effect of such a network on proton transport by studying the structural diffusion of protons using the quantum hopping molecular dynamics method. The mean residence time of the proton on a water molecule decreases by two orders of magnitude when the ? value is increased from 5 to 15. The proton diffusion coefficient in Nafion at a ? value of 15 is about 1.1x10-5 cm2/s in agreement with experiment. The results provide quantitative ...
Activation has been used for many kinds of useful applications, such as use of the radioisotopes for diagnosis and treatment of cancer, and wear (or corrosion) investigation for using thin layer activation (TLA) technique, etc. But activation also has severe problems for the post-processing of the samples; such as time-loss, inconvenience of sample handling, personal radiation safety, etc. For in-vitro experiments, we observed death of tumor cells by proton irradiation. The use of large activated container material can cause erroneous results in this case. To solve these problems, we studied why the samples were activated and how the level of the activation could be reduced. In proton beam irradiation experiments, the target materials could be defined as the container and sample itself. We could easily reduce activation of container material comparing to activation of sample itself. Therefore, we tried to find less activated container material ...
The "8"6Kr("3He,n)"8"8Sr and "8"8Sr("3He,n)"9"0Zr reactions were studied to determine whether significant excited 0"+ strength was observed or whether these nuclei exhibited absence of excited state strength generally seen away from shell closures. Various properties of the levels are considered including angular distributions, spins, parities, interference, and enhancement. It is concluded that neither "8"8Sr nor "9"0Zr exhibit the strong proton pairing vibration expected for a closed proton shell nucleus.
Decay sequences based on the 1/2"+[660] proton orbital have been identified in "1"7"1Ta and "1"7"7Re based on spin, parity, and large alignment. This decay sequence is observed higher in energy than predicted in cranking calculations based on modified oscillator potentials. Similarly known 1/2"-[541] decay sequences in these and other neighbouring isotopes are observed lower in energy than predicted. A reduction in the strength of the spin-orbit potential for protons is suggested as a solution to these problem. (orig.).
A calorimetric-time-of-flight (CTOF) technique was used for real-time, high-precision measurement of neutron spectrum at the angle of 175 degrees from the initial proton beam direction, which hits a face plane of a cylindrical iron target of 20 cm in diameter and 25 cm thick. A comparison was performed between the neutron spectra predicted by the MARS and the MCNPX code systems and measured by experiments for 0.4-, 0.6-, 0.8-, 1.0-, and 1.2-GeV protons.
A simple highly efficient procedure has been developed for recovery of thallium radioisotopes from lead and bismuth targets irradiated by 1-GeV protons. The procedure is based on the use of extraction chromatography. The cross-sections have been determined for formation of {sup 200}Pb, {sup 201}Pb, {sup 202m}Pb, and {sup 203}Pb radioisotopes in targets from lead with natural isotopic composition, irradiated by 1-GeV protons.
A simple highly efficient procedure has been developed for recovery of thallium radioisotopes from lead and bismuth targets irradiated by 1-GeV protons. The procedure is based on the use of extraction chromatography. The cross-sections have been determined for formation of "2"0"0Pb, "2"0"1Pb, "2"0"2"mPb, and "2"0"3Pb radioisotopes in targets from lead with natural isotopic composition, irradiated by 1-GeV protons.
Special beam extraction channel is used at INR linac for isotope production. It starts from 160 MeV measuring and matching area of accelerator. This choice of beam extraction enables to direct to the target of isotope complex a proton beam of wide energy range up to 160 MeV. It is important for production of different types of nuclides. The measuring results of proton beam behavior in this region are presented. Required beam forming in 160 MeV measuring and matching area of accelerator and in beam extraction channel is discussed.
A mixture of aminoacids was irradiated by a scattered proton beam, its energy varying from 4 to 6.6 MeV, by doses up to 5 x 10"1"1 proton/cm"2 for studying the potentiality of abiogenic synthesis of biologically important compounds in space. It was ascertained that increase in the radiation dose and reduction of proton energy involve increase in effectiveness both of destruction of the initial aminoacid (tryptophan, tyrosine, glycine) and synthesis of the relevant dipeptide. Essential influence of mineral substrate on abiogenic synthesis of natural nucleotides under the action of diverse energy sources was pointed out
We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin-flip cross section in low-energy electron-proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam.
Because of limitation on neutron-incident data, it is difficult to obtain global optical model potential for neutrons. In contrast, there are some global optical model potentials for proton in detail. It is interesting to convert the proton-incident global optical potentials into neutron-incident ones. In this study we introduce (N-Z)/A dependent symmetry potential terms into the global proton-incident optical potentials, and then obtain neutron-incident ones. The neutron potentials reproduce total cross sections in an acceptable degree. However, a comparison with potentials proposed by other authors brings about a confused situation in the sign of the symmetry terms. (author).
It is built and tested a transition radiation detector (TRD) to discriminate positrons from protons in the balloon flight TS 93 experiment. It is presented the TRD performance using flight data obtaining a proton-positron rejection factor of the order of 10{sup -3}. During the 24 hour flight, the data in the momentum range 4-50 GeV/c are collected. Using the TRD together with the Silicon calorimeter, it is achieved an overall rejection factor of about 10{sup -5} of positron against the proton background over the entire momentum range.
Recently, organic semiconducting materials have gained a broad interest due to their potential for organic electronic devices such as organic light emitting diode (OLED), organic photovoltaic devices and organic field-effect transistors (OFETs). Optical properties of organic semiconducting materials are important for practical application. For example, the power conversion efficiency of organic photovoltaic devices is mainly affected by absorption properties of organic materials. Proton irradiation is one of the efficient methods to change the optical properties of organic materials. In this paper, we investigate the changes of optical properties of various polymers using the proton irradiation.
The NuMI proton beam at Fermilab currently delivers 120 GeV protons to the neutrino production target with design beam power capability to 400 kW. Upgrade capability to 700 kW is being prepared, with planning toward delivering 2.3 MW beam provided by the Project X accelerator upgrade plan. We report on the system of beam diagnostics and control used in operation of the NuMI beam. Also considered are the steps to provide a robust system for transport and targeting beam of 2 MW and beyond.
Characterization of high temperature superconducting film and bulk samples has been carried out using 2 MeV [alpha]-particle Rutherford backscattering, 2.4 MeV proton elastic scattering, 2.4 MeV proton-induced x-ray emission, 9 MeV proton induced [gamma]-ray emission and 100 MeV iodine elastic recoil detection analysis techniques. The objective was to compare different ion beam based techniques for: (i) compositional analysis; and (ii) consistency of the results obtained for samples prepared using similar preparation methodology. (author).
Decay sequences based on the 1/2/sup +/(660) proton orbital have been identified in /sup 171/Ta and /sup 177/Re based on spin, parity, and large alignment. This decay sequence is observed higher in energy than predicted in cranking calculations based on modified oscillator potentials. Similarly known 1/2/sup -/(541) decay sequences in these and other neighbouring isotopes are observed lower in energy than predicted. A reduction in the strength of the spin-orbit potential for protons is suggested as a solution to these problem.
A feasibility on the development of a high energy proton accelerator to be used for R and D in the nuclear field of korea was studied. The proposed one is a proton linac with parameters of about 1 GeV, 20 mA which can supply enough neutrons by the spallation reaction to drive a subcritical reactor. It= is expected to solve the intrinsic problem in the nuclear field such as safety, nuclear waste, proliferation and resource. The study was carried out through a multi-institutional cooperation of universities, institute and industry for a national consensus. 5 refs., 8 tabs., 8 figs. (author)
A concept of a traveling wave direct energy converter (TWDEC) is developed for 14.7-MeV fusion protons based on the principle of a backward wave oscillator. Separation of fusion protons from thermal ions is accomplished by using ExB ion drift. Energy conversion rate up to 0.87 is attained by applying three-stage modulation of the proton beam. A one-dimensional particle-circuit code is developed to examine self-excitation of the traveling wave and its stability under loading. Electrostatic wave with a fixed frequency is excited spontaneously, and stability of the wave is ensured under loading. (author).
The available experimental data on the (/sup 3/He,n) reaction between the ground states of even-even nuclei and lowest 1/2/sup -/ levels of odd-A nuclei in the Aapprox.=100 region are analyzed in a systematic way by the DWBA. The deduced relative intensities of these two-proton transfers, and their uncertainties, are compared to the predictions of various nuclear models. In particular, the influence of the finite dimension of the configuration space available to the transferred protons, and of the blocking effect of a 2p1/2/sup -/ proton, are examined. (orig.).
W. Wayne Scott and R. G. Alsmiller, Jr. ABSTRACT. Comparisons of the results obtained for a hypothetical problem with four different proton penetration ...
We develop the formalism of a unified semi-microscopic description of low-energy proton and {alpha}-particle interaction with nuclei. We analyze elastic and inelastic proton scattering at the energy 25.05 MeV and {alpha}-particle scattering at the energy 104 MeV by the {sup 90}Zr nucleus. Information is obtained on differences in the deformation of the proton and neutron distributions. We study the energy dependence of the semi-microscopic {alpha}-particle potential including the energy dependence of the potential geometry.'' We analyze the change in angular distributions of elastically scattered {alpha} particles with increase of energy and the contribution to the scattering cross section from nucleon-nucleon correlations.
The process of radiation induced electron capture by protons or deuterons producing new ultra low momentum neutrons and neutrinos may be theoretically described within the standard field theoretical model of electroweak interactions. For protons or deuterons in the neighborhoods of surfaces of condensed matter metallic hydride cathodes, such conversions are determined in part by the collective plasma modes of the participating charged particles, e.g. electrons and protons. The radiation energy required for such low energy nuclear reactions may be supplied by the applied voltage required to push a strong charged current across a metallic hydride surface employed as a cathode within a chemical cell. The electroweak rates of the resulting ultra low momentum neutron production are computed from these considerations.
The energy spectra and angular distributions of proton emission in a reaction of {sup nat}Fe(n,xp) at a neutron energy of 14.6 MeV are measured by the University of Science and Technology of China multitelescope system. The double-differential cross sections of 16 reaction angles from 25 to 164.5 deg are obtained in this measurement. The statistical errors are reduced largely because of the thick target used. The angular distributions show a slightly energy-dependent forward-backward asymmetry. The angle-integrated proton spectrum is compared with theoretical calculations and other results. The total proton-emission cross section is in fair agreement with the prediction and evaluation.
TiH{sub 2} and TiD{sub 2} thick targets were bombarded with 100 to 200 keV protons or deuterons. Evidence for nuclear reactions was obtained by means of a surface barrier particle detector. Deuteron irradiation of TiD{sub 2} produced these observations: copious {approx}2.5 MeV neutrons and {approx}3 MeV protons from direct D-D reactions; gamma rays from p,{gamma} and n,{gamma} reactions; {approx}14 MeV protons from the secondary d({sup 3}He, p){alpha} reaction; and a signal between {approx}6-12 MeV that Kasagi et al. has tentatively identified as protons from the fusion of three deuterium nuclei. However, this signal has in it a strong interference signal from either neutrons or gamma rays that directly deposit energy in the detector. This interference spectra was measured by placing a thick absorber in front of the detector that stops up to 20 MeV protons, but not gamma rays or ...
Research conducted since the last progress report includes the synthesis and characterization of twenty three novel proton-ionizable crown ether compounds. Metal ion complexation behavior of new and previously-synthesized proton-ionizable crown ether compounds has been probed by solvent extraction and transport across polymer-supported liquid membranes. The behavior of neutral polyether and proton-ionizable polyether ligands in polymeric membrane electrodes has been assessed. Studies of the use of proton-ionizable crown ethers for separation of lithium isotopes were initiated. Also, the thermodynamics of interactions between alkali metal cations and ionized crown ethers have been probed by titration calorimetry. 10 refs., 1 tab.
The behavior of proton transfer facilitated by a novel thiazole derivative, N-methyl-4-(4-phenoxyphenyl)thiazol-2-amine (MPPT), across the water/1,2-dichloroethane (1,2-DCE) interface was investigated electrochemically. The ionic partition diagram for MPPT was obtained from interpretation of the cyclic voltammograms. The apparent partition coefficient of MPPT was evaluated by the shaking-flask method under experimental conditions, while that for the protonated form of MPPT was calculated from its transfer potential obtained from the ionic partition diagram. It was suggested that the mechanism for transfer of MPPT across the water/1,2-DCE) interface depends on the pH of the aqueous phase. The parameters of the facilitated proton transfer across the water/1,2-DCE interface were evaluated as ...
Neutron time-of flight spectra were measured from 90 MeV protons and 140 MeV alpha-particle bombardment of Al, Ni, Zr, and Bi at laboratory angles between 20/sup 0/ and 130/sup 0/. The proton induced neutron spectra reveal three distinct energy regions; a low energy evaporation region, a high-energy region dominated by quasi-free scattering processes and an intermediate-energy region dominated by multi-step, pre-equilibrium processes. In the latter two regions, the spectra show strong angular dependence. The alpha-induced neutron spectra show these same distinct energy regions plus an exponential fall-off above the beam energy per nucleon. The high-energy portions of the forward-angle neutron and proton cross sections are in ratios consistent with the assumption that single nucleon-nucleon scattering dominates. For heavy-mass targets, the low-energy evaporation regions show neutron yields larger than ...
Neutron time-of flight spectra were measured from 90 MeV protons and 140 MeV alpha-particle bombardment of Al, Ni, Zr, and Bi at laboratory angles between 20"0 and 130"0. The proton induced neutron spectra reveal three distinct energy regions; a low energy evaporation region, a high-energy region dominated by quasi-free scattering processes and an intermediate-energy region dominated by multi-step, pre-equilibrium processes. In the latter two regions, the spectra show strong angular dependence. The alpha-induced neutron spectra show these same distinct energy regions plus an exponential fall-off above the beam energy per nucleon. The high-energy portions of the forward-angle neutron and proton cross sections are in ratios consistent with the assumption that single nucleon-nucleon scattering dominates. For heavy-mass targets, the low-energy evaporation regions show neutron yields larger than proton ...
We measured neutron time-of-flight spectra from 90 MeV protons and 140 MeV alpha particles bombarding thin targets of Al, Ni, Zr, and Bi at laboratory angles between 20_0 and 135_0. The low-energy (5 to 45 MeV) portions of the spectra were measured with 5 cm diameter by 5 cm deep NE-213 counters at 1 m flight paths with n-#betta# pulse-shape discrimination. The high-energy (35 to 150 MeV) portions of the spectra were measured with 12.7 cm diameter by 10.2 cm deep NE-102 counters at flight paths of 2.0 to 5.0 m. The proton-induced measured neutron spectra reveal three distinct energy regions: a low-energy evaporation region, a high-energy region dominated by the quasifree scattering process, and an intermediate-energy region dominated by multistep, preequilibrium processes. In the latter two regions, the spectra show strong angular dependence. The alpha-particle induced neutron spectra show these same distinct energy regions plus an exponential ...
By method of transmission electron microscopy and measuring of microhardness the peculiarities of influence of radiation defect clusters on molybdenum radiation hardening along range path of protons with 30 MeV initial energy are studied. Decrease effect of hardening growth value and even its absence depending on irradiation dose in the range of 10-20 MeV proton energies in presence of high density of radiation defect dispersed clusters is revealed. It is shown experimentally that this effect is connected with accumulation of hydrogen up to not very high concentrations (not more than 5x10"-"4 at.%) at the expense of elastic and inelastic proton scattering. 5 refs.; 5 figs.
Proton exchange membrane (PEM) fuel cells are energy sources that have the ... for H2 /02 PEM fuel cells because their catalysts have properties suitable for 0 ...
Doubly decoupled structures in doubly odd deformed nuclei are reexamined and shown to be composed of a pseudo-spin aligned neutron and a decoupled proton. (orig.).
Doubly decoupled structures in doubly odd deformed nuclei are reexamined and shown to be composed of a pseudo-spin aligned neutron and a decoupled proton. (orig.).
A review of the deep-level defects observed in both electron- and proton-irradiated GaAs solar cells is presented. Studies of the effects of periodic and continuous thermal annealing on the radiation-induced electron and hole traps and the recombination parameters in GaAs solar cells were made for a wide range of electron and proton energies, fluence, annealing temperature and annealing time. A refined model for numerical simulations of the displacement damage was developed for computing the defect density and the cell parameters in the electron- and proton-irradiated GaAs solar cells. Excellent agreement was obtained between the calculated values and the experimental data for the proton-irradiated GaAs solar cells. (orig.).
Copper deficiency is associated with impaired brain development and mitochondrial dysfunction. Perinatal copper deficiency was produced in Holtzman rats. In vivo proton NMR...Full Text Available
We study the characteristics of cyclotron wave-particle interaction in a typical hydrogen plasma. The numerical calculations of minimum resonant energy Emin, resonant wave frequency ?, and pitch angle diffusion coefficient D?? for interactions between R-mode/L-mode and electrons/protons are presented. It is found that Emin decreases with ? for R-mode/electron, L-mode/proton and L-mode/electron interactions, but increase with ? for R-mode/proton interaction. It is shown that both R-mode and L-mode waves can efficiently scatter energetic (10 keV-100 keV) electrons and protons and cause precipitation loss at L=4, indicating that perhaps wave-particle interaction is a serious candidate for the ring current decay. (authors)
It is shown that elastic scattering data for protons of 100-200MeV are consistent with an absorptive potential that is stronger in the nuclear interior and of the slightly shorter range than is usually assumend, which is more in agreement with microscopically calcuated potentials. Consequences for certain (p,p') and (e,e'p) reactions are shown. (orig.).
We irradiated proton beams on the ears of rabbits and the Harding-Passey mouse melanoma and observed their morphological change. We used 52 MeV proton beams from the INS-FM cyclotron. We adjusted the energy of the proton beams to be at the plateau part of the Bragg curve, at the half-way point of the Bragg peak, and at the Bragg peak. The amount of radiation was 5000rad in each case. The Harding-Passey mouse melanoma was transplanted into the subcutan of a three week old mouse. In this experiment, we used tumors, the diameter of which grew up to 1.5-2cm in 2-3 weeks after the transplantation. Using the jroscope, we observed both lightly and severely damaged cells. Using proton irradiation with the Bragg peak located at depth of 1mm in the rabbit's ears, we studied the change in the tissue. Irradiated epidermis fell off and was eroded because of radiation damage, but the rear surface of the ...
The thermal stability of diffusion barriers is explored on the basis of Bi films at different expedients of deriving of films. The examinations were conducted on the electrostatic accelerator at KNU of name Karazin V.N. under conditions of an isothermal bakeout directly under a proton beam of 1,85 MeV energy.
Scheme of theoretical method of molecular configuration definition for small organic molecules in solution has been presented. The method bases on measurements of nuclear Overhauser effects for proton-proton interactions and molecular mechanics calculations. 3 refs, 1 fig.
The proton therapy gives an irradiation adapted to the shape and the depth of tumors ( eyes, head and neck) with a millimetric, even sub millimetric precision for the ophthalmological tumors. It is equally an excellent tool for the pediatrics tumors. For numerous treatments in France the proton therapy is associated to the photons treatments (x radiation). however, others physical treatments could modulate the medical offer, such thermal therapy or treatments by ultrasonic waves. (N.C.)
The constancy in excitation energy of the lowest 2/sup +/ state in the Sr isotopes across the N=56 subshell closure is shown to result from a reduction in the 2psub(1/2)-2psub(3/2) proton spin-orbit splitting as the 2dsub(5/2) neutron orbital is filled.
The wavefunction of a particle extends into the classically forbidden barrier region of the potential energy surface. The consequence of this partial delocalisation is the phenomenon of quantum tunnelling, an effect which enables a particle to penetrate a potential barrier of magnitude greater than the energy of the particle. The tunnelling probability is an exponential function of the particle mass. The effect is therefore an important contribution to the behaviour of light atoms, in particular the proton. The hydrogen bond has long been appreciated to be an essential component of many biological and chemical systems, and the proton transfer reaction in the hydrogen bond is fundamental to many of these processes. The proton behaviour in the hydrogen bonds of benzoic acid, acetylacetone and calix-4-arene has been studied. A variety of techniques, both experimental and computational, were adopted for the study of the three ...
It is shown that elastic scattering data for protons of 100-200MeV are consistent with an absorptive potential that is stronger in the nuclear interior and of the slightly shorter range than is usually assumend, which is more in agreement with microscopically calcuated potentials. Consequences for certain (p,p') and (e,e'p) reactions are shown.
A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.
At the beginning of the seventies, physicists discovered a new scale in the matter structure. Protons and neutrons, components of the atomic nucleus, seemed to be constituted by even more elementar particles: the quarks. But while they seemed to move freely inside the protons, it was impossible to isolate one of these quarks. The Nobel Prize for physics rewarded the explanation of this phenomenon (3 pages)
A study of the 150-300 keV proton beam transmission through glass (borosilicate) tapered capillaries with different diameters of the input and output of the capillary was performed. The focusing effect was observed. The areal density of the transmitted beam is enhanced by approximately 20 times. It was shown that changing a taper angle from 0.5 deg to 1.7 deg evidences the increase of the transmission coefficient more than by 300 times keeping the initial energy spectrum of ions. (author)
Purpose: This study presents a dosimetric optimization effort aiming to compare intensity-modulated (IM) X-rays and IM protons in 4 different orbital and paraorbital tumors. These are most challenging targets for standard radiotherapy due to their close relationship with the eyes and related structures. Methods and Materials: A primary orbital lymphoma, an optic nerve meningioma, a sphenoidal ridge meningioma protruding into the orbit, and a pediatric parameningeal paraorbital rhabdomyosarcoma were selected for the purpose of this study. Planning target volumes (PTVs) and organs at risk (OAR) were defined in each patient CT data set for each tumor site. IM X-ray and IM proton three-dimensional treatment plans were implemented. The following total tumor doses were prescribed: 30 Gy for the orbital lymphoma, 54 Gy for both meningiomas, and 50.4 Gy for the rhabdomyosarcoma case. Dose-volume histograms (DVHs) were obtained for all targets and OAR ...
A polarized proton physics run took place during January, 1988, at the Brookhaven AGS. It is the purpose of this paper to review the tune-up period preceding that run. This was the third such run at the AGS; the others occurred in June of 1984 and February of 1986. Some comparisons will be drawn among these. A thorough review of the history and hardware associated with the acceleration of polarized protons at the AGS can be found in the proceedings of the last meeting of this group at Protvino and will not be repeated here. 2 refs., 6 figs., 1 tab.
Peak at 60 deg in angular proton distribution in inelastic pion-carbon interactions is interpreted as generation of Cherenkov gluon radiation in flucton, passing into the shock wave with successive nucleus decay. Investigation of hadron-nuclear interactions with anomalous peak in angular proton distribution can be used as additional means for study both of flucton and mechanism of hadron-nuclear interactions. 5 refs.
A "9"2Mo beam with an energy of E/A=70 MeV has been used to produce new isotopes near the proton drip line. The Michigan State University National Superconducting Cyclotron Laboratory A1200 fragment separator was used to detect the new isotopes "7"8Y, "8"2Nb, "8"5Mo, "8"6Tc, and "8"9","9"0Ru.
A {sup 92}Mo beam with an energy of {ital E}/{ital A}=70 MeV has been used to produce new isotopes near the proton drip line. The Michigan State University National Superconducting Cyclotron Laboratory A1200 fragment separator was used to detect the new isotopes {sup 78}Y, {sup 82}Nb, {sup 85}Mo, {sup 86}Tc, and {sup 89,90}Ru.
Monte Carlo calculations performed to validate observed capture reaction rates of "1"2"9I and "2"3"7Np were in a reasonable agreement with experimental data obtained by the Joint Institute for Nuclear Research. The most significant discrepancy between the measurements and calculations (within a factor of 3) was observed for the NpO_2 sample and Pb target at 3.7 GeV proton energy
"La Universidad de Valencia tiene avanzado el diseno de un acelerador lineal de protones, cuya culminacion depende del compromiso del Consell en sufragar la plantilla que necesitaria el centro para estar operativo" (1 page).
Ksub(#beta#)/Ksub(#alpha#) X-ray intensity ratios have been measured for various elements between Z = 29 and Z = 79 for incident proton energies of 23.6, 32.1 and 43.6 MeV. The results yield no evidence for a variation in ratio with particle energy. (orig.).
The Ksub(#beta#)/Ksub(#alpha# 12) x-ray intensity ratio of the Si K spectrum was measured for proton impact on Si0_2 in the energy range 300-800 keV. An energy dependence of the intensity ratio was found and an explanation is given in terms of multiple ionisation. (author).
Cross sections for elastic scattering of 12 GeV protons from /sup 40/Ca nuclei have been calculated using the flucton model. The influence of the collective flucton nucleon correlations on the calculated cross sections is examined. The calculated cross sections are in significant disagreement with the experimental data. This may be considered as an argument against the flucton model.
Cross sections for elastic scattering of 12 GeV protons from "4"0Ca nuclei have been calculated using the flucton model. The influence of the collective flucton nucleon correlations on the calculated cross sections is examined. The calculated cross sections are in significant disagreement with the experimental data. This may be considered as an argument against the flucton model. (orig.).
Differences of the deformation parameters for the 2"+_1 states of even-even spherical nuclei extracted from electromagnetic excitation #beta#sup(em)_2 and from proton scattering #beta#sup(pp')_2 are discussed. It is found that the ratio #beta#sup(pp')_2/#beta#sup(em)_2 is equal to about unity and that there is a small isotope dependence for several incomplete shell nuclei. (orig.).
The authors present some precision measurements on electroweak physics performed at the Tevatron collider at Fermilab. Namely they report on the boson-pair production cross sections and on triple gauge boson couplings using proton anti-proton collisions collected by the CDF and D0 experiments at the center-of-mass energy of 1.96 TeV. The data correspond to an integrated luminosity of up to 324 pb{sup -1}.
The K"+- and K"-meson cumulative production cross sections are measured at 119"0 in the laboratory system on nuclei Be, Al, Cu and Ta bombarded by 10 GeV protons. Spectra of the K"-mesons consisting of only sea quarks show universal features characteristic of the spectra of cumulative particles, which contain valence quarks. Evidence is obtained for the fact that the energy density in a flucton can exceed the mean nuclear density by an order of magnitude.
Independent calculations of the antiproton-to-proton ratio by Gaisser and Maurer and by Badhwar et al. have produced conflicting results which obscure the interpretation of recent measurements of cosmic ray antiprotons. A detailed reexamination of these calculations has been performed and these differences have been resolved. We find that the first calculation was essentially correct and the reported fluxes of antiprotons are significantly higher than expected for secondary antiprotons in conventional models of cosmic ray propagation, as indicated by other recent calculations.
The available measurements on the cosmic-ray antiproton/proton ratio show an excess of antiprotons above predictions derived in the framework of the standard picture of cosmic-ray origin and propagation. Calculations are performed of the production from collisions of cosmic rays with the interstellar gas under the condition of distributed reacceleration. It could be shown that the calculated antiproton/proton ratio is enhanced compared to that derived from the leaky box model, but it remains difficult to bring it into agreement with the data by reasonable astrophysical assumptions. 15 references.
The work presented in part 1 of this study established that the sorption of anhydrous HX into dehydrated Na{sub 56}Y progresses through a sequence of steps involving HX ionization and charge separation, oxygen framework protonation, formation of {alpha}-cage confined cation-anion contact ion pairs, and proton solvation by HX. A logical extension, which is the subjected of this study, concerns the effect of extraframework alkali metal cation type (M = Li{sup +}, Na{sup +}, K{sup +}, Rb{sup +}, Cs{sup +}) on the sorption process. The question of the acidity of proton-loaded zeolites compared to Broensted acid zeolites is addressed by using probe reactions with weak bases like ethane and cyclopropane. Additional insight into these systems is also obtained from a quantitative comparison of the kinetic and thermodynamic activation parameters for the dehydrohalogenation of proton-loaded zeolites exemplified ...
We examined whether proton magnetic resonance spectroscopy (MRS) could provide accurate information on histological grade and cell proliferation in astrocytomas. We studied 23 patients with astrocytomas: five grade II, 10 grade III and eight with grade IV (glioblastoma multiforme). We performed proton MRS and determined the Ki-67 labeling index (LI), a tumour proliferation marker, in the same areas of the astrocytomas, and examined the statistical relationship between proton MRS and Ki-67 LI. The N-acetylaspartate (NAA)/creatine-phosphocreatine (Cr) and NAA/choline (Cho)-containing compound ratios were always significantly lower and the Cho/Cr ratios significantly higher than those for normal brain. The Cho/Cr ratio correlated positively and the NAA/Cho ratio inversely with Ki-67 LI. These findings suggest that the Cho signal in proton MRS reflects cellular proliferation. In Kaplan-Meier survival ...
Protonic ceramic membrane fuel cells (PCMFCs) based on proton-conducting electrolytes have attracted much attention because of many advantages, such as low activation energy and high energy efficiency. A stable, easily sintered perovskite oxide BaCe_0_._5Zr_0_._3Y_0_._1_6Zn_0_._0_4O_3_-_#delta# (BCZYZ) as electrolyte for proton-conducting solid oxide fuel cells (SOFCs) with Sm_0_._5Sr_0_._5CoO_3_-_#delta# (SSC) composite cathode is investigated. By fabricating thin membrane BCZYZ electrolyte (#approx#20 #mu#m) synthesized by a modified Pechini method on NiO-BCZYZ anode support, PCMFCs are assembled and tested by selecting SSC perovskite cathode with high mixed ionic and electronic conductivities. An open-circuit potential of 1.015 V, a maximal power density of 528 mW cm"-"2, and a low polarization resistance of the electrodes of 0.15 #OMEGA# cm"2 is achieved at 700 "oC. The results indicate that BCZYZ ...
In clinical applications, it is very important to accurately determine the range of a proton beam in a patient. Recently, a prototype prompt-gamma scanning system, called a prompt-gamma scanner (PGS), has been constructed at Hanyang University in Korea with the collaboration of the Korean national cancer center (NCC), based on a series of Monte Carlo simulations. The PGS system is composed of a prompt-gamma collimator, a CsI(Tl) scintillation detector, a multi-channel analyzer (MCA), a precision movement system, and an integrated readout system. The prompt-gamma collimator is designed to effectively shield high-energy neutrons from the proton beam passage and subsequent capture gammas. The PGS system can be used to scan the distribution of the prompt gammas in the patient from the proton beam passage. The distribution of the prompt gammas can then be used to determine the proton beam range or the distal ...
The results of investigation into a new series of Z-even nuclei - precursors of delayed protons (PDP) -"6"5Ge, "8"9Se, "9"3Kr, "8"1Zr, and "8"5Mo are presented. PDP were obtained by irradiation of targets in the following reactions: Zn(He, 2n) "6"5Ge, 22 MeV; "4"0Ca("3"2S, 2 pn) "1"9Se, 100 MeV; "6"0Ni ("1"60, 3 n), "7"3Kr, 75 MeV; "5"2Cr ("3"2S, 3n)"8"1Zr, 110 MeV; "5"6Fe("3"2S, 3n)"8"5Mo, 120 MeV. The targets (self-sustaining foils of thickness approximately 1.2 mg/cm"2) were placed at an angle of 15 deg to the direction of the ion beam. Upon irradiation targets were moved downwards into a measuring position. The spectra of protons, X and gamma-rays, and also the spectra of p - x, p-#gamma#, x - #gamma# coincidences accompanying the decay of "6"5Ge, "6"9Se,"7"3Kr and "8"1Zr, and "8"5Mo were measured. The measured half-lives are equal, to 31.5+-1.9, 27.3+-0.5, 28.5+-1.1, 6.3+-0.5, and 5.6 +-0.9 s respectively. The experimental spectra are ...
The acid-base behavior of the ground and excited states of Pt(qdt){sub 2}{sup 2{minus}} and Pt(phen)(qdt), where qdt=quinoxaline-2,3-dithiolate and phen = 1,10-phenanthroline, has been studied. The pH-dependent changes in the charge-transfer absorption and emission spectra for both complexes are attributed to protonation of the quinoxalinedithiolate ligand at the imine nitrogen. For Pt(qdt){sub 2}{sup 2{minus}}, single protonation leads to a large red shift (2582 cm{sup {minus}1}) of the low-energy charge-transfer-to-dithiolate absorption band and the emergence of a new red-shifted emission feature at 728 nm. In solutions of pH below 6, a second protonation takes place at the other qdt ligand, yielding Pt-(Hqdt){sub 2}. This neutral complex has been isolated and characterized by {sup 1}H NMR spectroscopy and elemental analyses. The ground-state basicity constants of the two protonation steps have been ...
Using a noneikonal expression for the two-body scattering amplitude, consistent with the proton-nucleon scattering data, the cross-section of the 1.04 GeV-proton elastic scattering on {sup 40}Ca is calculated by the Glauber-Sitenko theoretical scheme in the framework of the coherent density fluctuation model (CDFM) as well as of the independent-particle model (IPM). It is shown that the use of the noneikonal amplitude in the CDFM calculations improves the agreement with the experimental data especially at larger scattering angles in contrast to the case of the independent-particle model. To that end a decisive role play the zero-motion flucton correlations taken into account in the CDFM. (orig.).
Using a noneikonal expression for the two-body scattering amplitude, consistent with the proton-nucleon scattering data, the cross-section of the 1.04 GeV-proton elastic scattering on "4"0Ca is calculated by the Glauber-Sitenko theoretical scheme in the framework of the coherent density fluctuation model (CDFM) as well as of the independent-particle model (IPM). It is shown that the use of the noneikonal amplitude in the CDFM calculations improves the agreement with the experimental data especially at larger scattering angles in contrast to the case of the independent-particle model. To that end a decisive role play the zero-motion flucton correlations taken into account in the CDFM. (orig.).
This report covers the progress made on the title project for the project period. Four major areas of inquiry are being pursued. Advanced solid state NMR methods are being developed to assay the distribution of the various important functional groups that determine the reactivity of coals. Special attention is being paid to methods that are compatible with the very high magic angle sample spinning rates needed for operation at the high magnetic field strengths available today. Polarization inversion methods utilizing the difference in heat capacities of small groups of spins are particularly promising. Methods combining proton-proton spin diffusion with [sup 13]C CPMAS readout are being developed to determine the connectivity of functional groups in coals in a high sensitivity relay type of experiment. Additional work is aimed at delineating the role of methyl group rotation in the proton NMR relaxation behavior of coals.
In a forthcoming paper we describe a new approach to rapidity gap survival (RGS) in the production of high-mass systems (H = dijet, Higgs, etc.) in exclusive double-gap diffractive pp scattering, pp -> p + H + p. It is based on the idea that hard and soft interactions are approximately independent (QCD factorization), and allows us to calculate the RGS probability in a model-independent way in terms of the gluon generalized parton distributions (GPDs) in the colliding protons and the pp elastic scattering amplitude. Here we focus on the transverse momentum dependence of the cross section. By measuring the ''diffraction pattern'', one can perform detailed tests of the interplay of hard and soft interactions, and even extract information about the gluon GPD in the proton from the data.
Elastic and inelastic proton scattering has been measured in inverse kinematics on the unstable nucleus {sup 40}S. A phenomenological DWBA analysis yields a quadrupole deformation parameter {beta}{sub 2} = 0.35 {+-} 0.05 for the 2{sup +}{sub 1} state. Consistent phenomenological and microscopic proton scattering analyses have been applied to all even-even Sulfur isotopes from A = 32 to A = 40. The microscopic analysis used microscopic collective model densities and a modified Jeukenne-Lejeune-Mahaux effective interaction. This analysis suggests the presence of a neutron skin in the heavy sulfur isotopes. The analysis is consistent with normalization values for {lambda}{sub {upsilon}} and {lambda}{sub {omega}} of 0.95 for both the real and imaginary parts of the JLM potential. (author)
Polarization measurements are allowing the electric to magnetic form factor ratio of the proton to be determined with unprecedented precision. Recent results indicate that there is a large deviation from unity in the proton form factor ratio around Q{sup 2}{approx_equal}0.35 GeV{sup 2}. Furthermore, the deviation from unity is attributed to a deviation of the electric form factor from standard fits and calculations. A new, partially completed, experiment will significantly improve the existing data and will determine the presence, if any, of a narrow structure in the form factor ratio. The new measurement, combined with the expected high precision cross section measurements, will allow the extraction of individual form factors with unprecedented accuracy at low Q{sup 2}.
Experimental measurements were made of the production cross sections and energy distributions of gamma rays emitted when the stable targets /sup 88/Sr, /sup 89/Y and /sup 90/Zr are exposed to protons in the energy range 3 to 8 MeV. The data are being analyzed using a recent version of the Uhl statistical model code. One conclusion is that while the gamma-ray strength functions employed reproduce the proton capture cross sections, they do not achieve the same degree of hardness observed in the measured spectra. To do so, their lower energy regions must be modified; such changes, however, do not affect the capture cross sections. 7 references.
The proton and neutron densities, root-mean-square (rms) radii of proton density and neutron density, and neutron skin thickness of "4"-"1"0He, "6"-"1"1Li, and "7"-"1"2Be isotopes are calculated using Skyrme-Hartree-Fock method with SLy4, SLy5, SLy6, and SLy7 force parameters. The evaluated results are compared with experimental data. Also, the results of halo nuclei ("6","8He, "1"1Li, and "1"1Be) are compared with the results of other isotopes for selected nuclei having the same neutron configuration.
The article is devoted to results of fine time structure of particle losses in Tevatron with use of fast beam loss monitors (BLM) based on PIN-diodes. An ultimate goal of the new BLMs is to distinguish losses of protons and antiprotons from neighbor bunches with 132 ns bunch spacing in the Tevatron collider upgrade. The devices studied fit well to the goal as they can recognize even seven times closer - 18.9 ns - spaced bunches` losses in the Tevatron fixed target operation regime. We have measured main characteristics of the BLM as well as studied the proton losses over 10 decades of time scale - from dozen of minutes to dozen of nanoseconds. Power spectral density of the losses is compared with spectra of the proton beam motion.
A sulfonated fluoroalkyl graft polymer (FGP) membrane was prepared as a polymer electrolyte. First, the FGP membrane was grafted with styrene under UV irradiation. The grafted FGP was then sulfonated to functionalize it for proton conductivity. The grafting degree of the membrane increased with increasing grafting time during UV irradiation. The proton conductivity of the membrane increased with increasing grafting degree. The swelling ratio was independent of the grafting time, however, the water uptake increased with increasing grafting degree. Based on these results, it was found that the UV-initiated styrene grafting occurred along the membrane thickness direction. Moreover, the membrane was embedded within the glass fibers of the composite. This composite electrolytic membrane had 1.15 times the proton conductivity of a Nafion 117 membrane.
High temperature proton conductor (HTPC) oxides are attracting extensive attention as electrolyte materials alternative to oxygen-ion conductors for use in solid oxide fuel cells (SOFCs) operating at intermediate temperatures (400-700 "0C). The need to lower the operating temperature is dictated by cost reduction for SOFC pervasive use. The major stake for the deployment of this technology is the availability of electrodes able to limit polarization losses at the reduced operation temperature. This review aims to comprehensively describe the state-of-the-art anode and cathode materials that have so far been tested with HTPC oxide electrolytes, offering guidelines and possible strategies to speed up the development of protonic SOFCs. (topical review)
We compute the corrections from two-photon and {gamma}-Z exchange in parity-violating elastic electron-proton scattering, used to extract the strange form factors of the proton. We use a hadronic formalism that successfully reconciled the earlier discrepancy in the proton's electron to magnetic form factor ratio, suitably extended to the weak sector. Implementing realistic electroweak form factors, we find effects of the order 2%-3% at Q{sup 2} < or approx. 0.1 GeV{sup 2}, which are largest at backward angles and have a strong Q{sup 2} dependence at low Q{sup 2}. Two-boson contributions to the weak axial current are found to be enhanced at low Q{sup 2} and for forward angles. We provide corrections at kinematics relevant for recent and upcoming parity-violating experiments.
A 20-MeV proton accelerator is developed by Proton Engineering Frontier Project (PEFP) at Korea Atomic Energy Research Institute (KAERI). The 20MeV accelerator consists of 50keV proton injector, 3MeV RFQ (Radio frequency Quadrupole), 20MeV DTL (Drift Tube Linac) and 20MeV beam line. The beam profile was measured at the end of the 20MeV beam line with wire scanner. Moreover the beam emittance was calculated from the quad scan method using beam line quadrupole magnets. In this paper, the beam profile measurement results are presented and the emittance measurement from the quad scan method is discussed
Fourier transform infrared (FTIR) difference spectra have been obtained for the bR----K, bR----L, and bR----M photoreactions in bacteriorhodopsin mutants in which Asp residues 85, 96, 115, and 212 have been replaced by Asn and by Glu. Difference peaks that had previously been attributed to Asp COOH groups on the basis of isotopic labeling were absent or shifted in these mutants. In general, each COOH peak was affected strongly by mutation at only one of the four residues. Thus, it was possible to assign each peak tentatively to a particular Asp. From these assignments, a model for the proton-pumping mechanism of bR is derived, which features proton transfers among Asp-85, -96, and -212, the chromophore Schiff base, and other ionizable groups within the protein. The model can explain the observed COOH peaks in the FTIR difference spectra of bR photointermediates and could also account for other recent results on site-directed mutants of bR.
as for direct energy conversion in specialized direct electrical energy conversion plants. Figure 1. An energetic (~163KeV) proton and a 11boron nucleus fuse ...
SUMMARYIn voltage-gated sodium, potassium, and calcium channels the functions of ion conduction and voltage sensing are performed by two distinct structural units: the pore domain...Full Text Available
Electrophysiological events are of central importance during the phagocyte respiratory burst, because NADPH oxidase is electrogenic and voltage sensitive. We investigated the recent suggestion that...Full Text Available
Generation of reactive oxygen species by the NADPH oxidase complex is an important bactericidal weapon of phagocytes. Phorbol myristate acetate (PMA) is a potent agonist for this “respiratory...Full Text Available
When oxygen is limiting, animals can ferment glucose via several metabolic pathways varying in energetic efficiency and leading to various end products (such as lactate, succinate, or propionate). Because the pH dependence of H/sup +/ production by fermentation is opposite to that by hydrolysis of adenosine triphosphate formed in the fermentation, the total number of moles of protons generated is always two per mole of fermentable substrate. However, two and three times more adenosine triphosphate can be turned over per mole of protons produced in succinate and propionate fermentations, respectively, than in lactate fermentation. At its limit, this advantage would achieve the same balance between H/sup +/ production and H/sup +/ consumption during ATP cycling that is observed in aerobic metabolism, a situation observed in certain alcohol fermentations. Since proton balance during anaerobiosis is clearly adaptable, we ...
When any new accelerator or storage ring is built that advances the state of the art, the diagnostic system becomes extremely important in tuning the facility to full specification. This paper will discuss the various diagnostic devices planned or under construction for the PSR and their connection into the control system.
Lithium ammonium sulfate (LAS) undergoes a phase transition at Tsub(c1) = 459.5deg K from a paraelectric phase (phase 1) to a ferroelectric phase (phase II) and again at Tsub(c2) = 283deg K to a polar ferroelastic phase (phase III). Proton spin lattice relaxation investigations in the temperature range 480-77deg K at 10 MHz show discontinuous changes in Tsub(1) at the transition temperatures, indicating first order phase transitions. The absence of the slow motion region (#omega#sub(not)tausub(not)>>1) shows that the ammonium ions are reorienting fast enough to keep the resonance absorption line narrow down to liquid nitrogen temperatures. The possibility of a second minimum and a low activation energy, Esub(a) = 2.659 kcal/mole, in phase III suggest the possibility of tunnelling of the protons at low temperatures. The nature of the transitions have been discussed in the light of the available literature. The unusually high activation ...
The ratio of the proton's electric to magnetic form factor, G{sub E}/G{sub M}, can be extracted in elastic electron-proton scattering by measuring cross sections, beam-target asymmetry, or recoil polarization. Separate determinations of G{sub E}/G{sub M} by cross sections and recoil polarization observables disagree for Q{sup 2}>1 (GeV/c){sup 2}. Measurement by a third technique might uncover an unknown systematic error in either of the previous measurements. The beam-target asymmetry has been measured for elastic electron-proton scattering at Q{sup 2} = 1.51 (GeV/c){sup 2} for target spin orientation aligned perpendicular to the beam momentum direction. This is the largest Q{sup 2} at which G{sub E}/G{sub M} has been determined by a beam-target asymmetry experiment. The result, {mu}G{sub E}/G{sub M}=0.884{+-}0.027{+-}0.029, is compared to previous world data.
Amphiphilic block copolymers are synthesized by sulfonation of poly(styrene-b-methyl methacrylate) (PS-b-PMMA) using acetyl sulfate, and are blended with poly(vinylidene fluoride) (PVDF) to prepare a new proton exchange membrane, in which PMMA is miscible with PVDF. The morphology and the transport properties of the membranes are investigated as functions of the degree of sulfonation as well as the blend ratio. Notable transition of phase-separated morphology is observed as the PVDF content of the blend is increased. Both the proton conductivity and the ion-exchange capacity (IEC) of the membrane increase with increasing the degree of sulfonation of PS-b-PMMA, and they are also enhanced as the phase-separated domains of blend membrane are well-ordered. Unlike the Nafion membrane, the proton conductivity of the blend membrane increases up to 90 C, indicating the blend membrane shows better thermal stability than the Nafion ...
A red light-induced, far red reversible stimulation of proton efflux from apical segments of etiolated Avena sativa L. cv. Victory coleoptiles was observed. The acidification...Full Text Available
The quantitative estimation of various trace element concentrations in medicinal plants is necessary for determining their effectiveness in treating various diseases and for understanding their pharmacological action. Elemental concentrations of some selected medicinal plants of north east India was measured by proton induced X-ray emission (PIXE) and proton induced {gamma}-ray emission (PIGE) techniques. PIXE measurements were carried out using 2.4 MeV collimated protons from the 3 MV tandetron accelerator of NCCCM, Hyderabad (India) while the PIGE measurements were carried out using 3 MeV protons from the same accelerator in the same laboratory. Accuracy and precision of the techniques were assured by analyzing certified reference materials in the same experimental conditions. Various elements of biological importance in man's metabolism were found to be present in varying concentrations in ...
It has been discovered that iron(III) chloride complexes supported on activated charcoal oxidize phosphine under normal conditions. The process accelerates as the concentration of the chloride ions and the proton acid increases.
Probabilities of flucton production have been calculated for the 1p-shell nuclei and its modification by the Yastrov method. The results obtained are in a qualitative agreement with the data resulting from the analysis of experiment in an assumption of a flucton mechanism of proton-nuclear inclusive reactions with the production of cumulative particles.
BackgroundTo evaluate the performance of three different advanced treatment techniques on a group of complex paediatric cancer cases.MethodsCT...Full Text Available
W. Wayne Scott. ABSTRClCT. Primary proton and secondary particle doses (both .... W. Wayne Scott and R. G. Alsmiller, Jr., Comparisons of Results Ob- ...
First comprehensive data on the evolution of nucleon resonance photocouplings with photon virtuality Q{sup 2} are presented for excited proton states in the mass range from 1.4 to 2.0 GeV.
A new gadolinium chelating NIR fluorescent molecular probe increases T1 relaxivity of water protons, facilitating combined optical and magnetic resonance imaging.
The LSND (Liquid Scintillator Neutrino Detector) experiment will be performed at LAMPF in the next several years. The main goal of the experiment is to search for {nu}{sub {mu}}-{nu}{sub e} oscillations with high sensitivity; however, an increasingly important by-product of this search is to measure {nu}p {yields} {nu}p elastic scattering and determine the strange quark contribution, {Delta}s, to the spin of the proton. With the 800-MeV proton energy of LAMPF, neutrinos are produced from pion decay-in-flight with an average energy of about 150 MeV. This energy is sufficiently high so that the {nu}p {yields} {nu}p cross section is large and is sufficiently low so that the low Q{sup 2} approximation (Q{sup 2} {much lt} m{sub p}{sup 2}) is valid and the cross section can be expressed in a simple form dependent upon {Delta}s as the only unknown. LAMPF with its 1-mA proton intensity is, therefore, an ideal accelerator to perform ...
The weak interaction between neutrons and protons has never been resolved experimentally. In analogy with the strong NN interaction, the weak NN interaction at low energy can be parametrized in terms of a meson exchange model with parity violating meson-nucleon couplings. Unlike the measured proton-proton weak interaction, the neutron-proton weak interaction is sensitive to the weak pion-nucleon coupling constant H{sub {pi}}{sup 1}. This coupling, which is responsible for the longest-ranged part of the weak NN interaction and is therefore an essential part of any description of weak interactions in nuclei, remains undetermined despite many years of effort. A measurement of the gamma ray directional asymmetry A{sub {gamma}} in the capture of polarized neutrons by parahydrogen has been proposed at Los Alamos National Laboratory. The goal of this experiment is to determine A{sub {gamma}} with a relative standard uncertainty of ...
The mechanism of metabolic energy production by malolactic fermentation in Lactococcus lactis has been investigated. In the presence of L-malate, a proton motive force composed of a membrane potential...Full Text Available
The responses of the vacuolar membrane (tonoplast) proton-pumping inorganic pyrophosphatase (H+-PPase) from oat (Avena sativa L.) roots to changes in Mg2+ and...Full Text Available
Lactobacillus buchneri ST2A vigorously decarboxylates histidine to the biogenic amine histamine, which is excreted into the medium. Cells grown in the presence of histidine generate both a transmembrane...Full Text Available
Thermophilic propionate-oxidizing, proton-reducing bacteria were enriched from the granular methanogenic sludge of a bench-scale upflow anaerobic sludge bed reactor operated at 55°C with a mixture...Full Text Available
We report a detailed augmented-plane-wave energy-band study and wave-function analysis of stoichiometric PdH which shows that, even though the Fermi surface of PdH is qualitatively similar to that of silver, the simple ''proton model'' is not valid. Instead, the screening of the proton in PdH is found to be larger than in an isolated H atom due, in part, to the formation of a H-Pd bonding band below the bottom of the d-band complex. This result, which is in qualitative agreement with Switendick's earlier calculation, is confirmed by ultraviolet photoemission experiments. A partial density-of-states (DOS) analysis in the energy range spanned by the six valence and conduction bands reveals the quantitative details of the bonding mechanism between the Pd and H constituents. At the Fermi energy, the high Pd d to H s DOS ratio approx. 10.3 is found to be far higher than expected in silver, despite the fact that the Fermi-surface geometry is similar. ...
... ions. MATERIALS AND METHODS Cell Culture Culture of NT2/D1 cells was carried out as described previously (18, 19). NT2 cells were plated at a density of 2. ... ...
The system of the early forecast of radiation hazardous fluxes of solar cosmic rays in space on the basis of the real time neutron monitors data obtained by the NMDB (Neutron Monitor Data Base) network is created. The forecast system is based on a short cut technique of definition of a spectrum of solar protons from the data of the limited number of neutron monitor stations and with a simplified procedure of accounts. It is shown that the results of computations of solar proton spectra with the short-cut technique little differ from spectra obtained with a complete technique at energies less than 5 GeV. Thus the good agreement between derived from the neutron monitor data intensities of solar protons in an energy range of hundreds MeV with the data of direct measurements of solar protons at GOES-11 spacecraft is observed. The maximum of increase on neutron monitors outstrips on several hours (2-10) an ...
In voltage-gated Na+, K+, and Ca2+ channels, four voltage-sensor domains operate on a central pore domain in response to membrane voltage. In contrast, the voltage-gated...Full Text Available
Differential cross sections of elastic scattering of 104 MeV #alpha# particles from "2"0"4,"2"0"6,"2"0"8Pb have been measured with high angular accuracy. The analyses are based on a folding model treating the proton and neutron distributions independently. The proton distributions were taken from precise electron scattering results. The neutron distributions were parametrized by a modified Gaussian the parametrers of which were varied in order to fit the experimental cross sections. The resulting rms radii of the neutron distributions exceed the rms radii of the proton distributions by #DELTA#r=0.22 +- 0.09 fm for "2"0"4Pb, #DELTA#r = 0.19 +- 0.09 fm for "2"0"6Pb, and #DELTA#r = 0.30 +- 0.07 fm for "2"0"8Pb.
Correlations are studied between the power density of Alfv\\'en-cyclotron waves (having frequencies between 0.02 and 2 Hz) and the ratio of the perpendicular and parallel temperature of the protons. The wave power spectrum is evaluated from high-resolution 3D magnetic field vector components, and the ion temperatures are derived from the velocity distribution functions as measured in fast solar wind during the Helios-2 primary mission at radial distances from the Sun between 0.3 AU and 0.9 AU. From our statistical analysis, we obtain a striking correlation between the increases in the proton temperature ratio and enhancements in the wave power spectrum. Near the Sun the transverse part of the wave power is often found to be by more than an order of magnitude higher than its longitudinal counterpart. Also the measured ion temperature anisotropy appears to be limited by the theoretical threshold value for the ion-cyclotron instability. This ...
Compact dielectric wall (DWA) accelerator technology is being developed at the Lawrence Livermore National Laboratory. The DWA accelerator uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. Its high electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The DWA concept can be applied to accelerate charge particle beams with any charge to mass ratio and energy. Based on the DWA system, a novel compact proton therapy accelerator is being developed. This proton therapy system will produce individual pulses that can be varied in intensity, energy and spot width. The system will be capable of being sited in a conventional linac vault and provide intensity modulated rotational therapy. The status of the developmental new technologies that make the compact system possible will be reviewed. ...
The membrane properties of isolated cultured microglia have been extensively studied but it is important to understand their properties in situ, where they protect the brain against...Full Text Available
Biosorption of the heavy metal ion Cd{sup 2+} by protonated nonliving brown alga Sargassum fluitans biomass was accompanied by the release of hydrogen protons from the biomass. The uptake of cadmium and the release of proton matched each other throughout the biosorption process. The end-point titration methodology was used to maintain the constant pH 4.0 for developing the dynamic sorption rate. The sorption isotherm could be well represented by the Langmuir sorption model. A mass transfer model assuming the intraparticle diffusion in a one-dimensional thin plate as a controlling step was developed to describe the overall biosorption rate of cadmium ions in flat seaweed biomass particles. The overall biosorption mathematical model equations were solved numerically yielding the effective diffusion coefficient D{sub e} about 3.5 {times} 10{sup {minus}6} cm{sup 2}/s. This value matches that obtained for the desorption process ...
To calibrate channels A1 to A4 for particles with Z >= 1, tests were done on the IBIS accelerator at AERE, Harwell, which gave protons up to 3 MeV. ...
A technique of low-field pulsed proton nuclear magnetic resonance (NMR) spin relaxation is described for assessment of age-related structural changes (dentin and pulp) of human teeth in...Full Text Available
The 1.04 GeV-proton elastic scattering from /sup 40/Ca is studied in the framework of the coherent density fluctuation model (CDFM). The calculations are carried out in the Glauber theoretical scheme with three different charge densities. It is shown that: i) the account of the flucton correlations leads to results considerably different from those obtained in the independent particle Glauber approach (IPGA); ii) in contrast to the case of IPGA the use of a more realistic density improves the agreement of CDPM-results with the experimental data.
The 1.04 GeV-proton elastic scattering from "4"0Ca is studied in the framework of the coherent density fluctuation model (CDFM). The calculations are carried out in the Glauber theoretical scheme with three different charge densities. It is shown that: i) the account of the flucton correlations leads to results considerably different from those obtained in the independent particle Glauber approach (IPGA); ii) in contrast to the case of IPGA the use of a more realistic density improves the agreement of CDPM-results with the experimental data. (orig.).
We studied two-photon exchange for elastic electron-proton scattering at low Q{sup 2}. Compact approximate formulas for the amplitudes were obtained. Numerical calculations were done for Q{sup 2}{<=}0.1 GeV{sup 2} with several realistic form factor parametrizations, yielding similar results. They indicate that the corrections to the magnetic form factor can visibly affect the cross-section and proton radii. For low-Q{sup 2} electron-neutron scattering two-photon exchange corrections were shown to be negligibly small00.
Unique measurement of the proton structure function F2 in a wide two-dimensional region of x and Q**2 has been reported. The accessible kinematics covers entire resonance region up to W=2.5 GeV in the Q**2 interval from 0.1 to 4.5 GeV**2. Obtained data allowed for the first time an evaluation of moments of the structure function F2 directly from experimental data as well as an intensive study of the Bloom-Gilman duality phenomenon.
The conceptual design for a cyclotron that could possibly deliver a 10 MW proton beam, presented at the previous ADTT conference, is discussed in comparison with the operational experience gained with 0.9 MW beam power in the upgraded cyclotron facility at PSI that has reached the design goal of 1.5 mA at 590 MeV in 1995. Some critical aspects of the design are e.g. RF power and beam loading, beam loss and activation, space charge effects and bunching. 12 refs., 2 figs., 1 tab.
Surface doping of conjugated polymers is realized by depositing a thin layer of graphene oxide (GO) on top of the polymers. The high proton density and the unique 2D structure of GO facilitate the protonic surface doping of conjugated polymers to achieve high conductivities. This finding represents a new strategy for improving charge transport across the metal/conjugated polymer interface to achieve much improved performance in organic solar cells. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Sol-gel chemistry has a great many potential applications in the preparation of unique electrochemical materials, from non-equilibrium transition metal oxides which may be of use as high energy density electrodes, to high-surface area mixed oxides which may possess high proton conductivity, to novel composite structures consisting of inorganic gels in combination with organic, electronic, and ionic conductors. This paper reviews prior work on proton conduction in gel systems and presents recent work regarding electrode materials prepared by sol-gel methods and inorganic-organic materials.
A method is proposed for the quantitative isolation of radiothallium in gas form from proton-bombarded lead of mass up to 20 g. The molten lead is kept at about 800 K in hydrofluoric-acid vapor (HF/H/sub 2/O approx. = 1) at a reduced pressure (less than or equal to4 Pa). We used 99.9% lead with the U-240 cyclotron at the Nuclear Research Institute, Academy of Sciences of the Ukrainian SSR, or the phasotron at the Join Nuclear Research Institute, which gave protons at 65 and 680 MeV correspondingly.
A method is proposed for the quantitative isolation of radiothallium in gas form from proton-bombarded lead of mass up to 20 g. The molten lead is kept at about 800 K in hydrofluoric-acid vapor (HF/H_2O #approx =# 1) at a reduced pressure (#<=#4 Pa). We used 99.9% lead with the U-240 cyclotron at the Nuclear Research Institute, Academy of Sciences of the Ukrainian SSR, or the phasotron at the Join Nuclear Research Institute, which gave protons at 65 and 680 MeV correspondingly.
The study of imported ceramics found in Beirut and suspected to belong to north Syrian products will provide key evidence for the roles in trade of the various postulated centers in northern Syria and northern Lebanon. It is proposed that a comprehensive range of likely north Syrian products imported to Beirut will be chemically analyzed by PIXE (proton induced X-ray emission) in order to characterize, compare and isolate the various regional production centers that supplied the city from the Persian to Byzantine periods. In this work, we were mainly focusing on the characterization of Amrit products, by using 3 MeV proton beam and Al funny filter, as X-ray absorber.
The RSS collaboration has measured the spin structure functions of the proton and the deuteron at Jefferson Lab using the Hall C HMS spectrometer, a polarized electron beam and a polarized solid target. The asymmetries A and A were measured in the region of the nucleon resonances (0.82 GeV < W < 1.98 GeV) at an average four momentum transfer of Q2 = 1.3 GeV2. The extracted spin structure functions and their kinematic dependence will make a significant contribution in the study of higher-twist effects and polarized duality tests. A description of the experiment and the latest findings of the analysis will be presented.
We analyse data on forward {eta} -meson photoproduction off a proton target and extract the {eta}{yields}{gamma}{gamma} decay width utilizing the Primakoff effect. The hadronic amplitude that enters into our analysis is strongly constrained because it is fixed from a global fit to available {gamma}p{yields}p{eta} data for differential cross-sections and polarizations. We compare our results with present information on the two-photon {eta} -decay from the literature. We provide predictions for future PrimEx experiments at Jefferson Laboratory in order to motivate further studies. (orig.)
Polarized antiprotons produced by spin filtering with an internal polarized gas target provide access to a wealth of single- and double-spin observables, thereby opening a window to physics uniquely accessible with the HESR at FAIR. This includes a first measurement of the transversity distribution of the valence quarks in the proton, and a first measurement of the moduli and the relative phase of the time-like electric and magnetic form factors G{sub E,M} of the proton. In polarized and unpolarized pp-bar elastic scattering open questions like the contribution from the odd charge-symmetry Landshoff-mechanism at large |t| and spin-effects in the extraction of the forward scattering amplitude at low |t| can be addressed.
The proton momentum distributions of (39)K,(40)Ca and (48)Ca are calculated from the model-independent charge distributions obtained from analyses of electron elastic scattering and muonic atoms, and also from the charge distributions calculated from the single-particle potential method in the framework of the flucton model. The sensitivities of the momentum distribution to different regions of the charge distribution are determined. The analysis is extended to the neutron distributions using the single-particle potential method, and the differences between the proton and neutron momentum distributions are examined. The resulting momentum distribution in the case of (40)Ca is used for analyzing the quasielastic electron scattering.
A ''coherent flucton'' nuclear model is proposed which provides for new possibilities for particle scattering studies on nuclei. It is based on the data of nuclear matter density distribution and is used for calculating the ground state energy of Fermi system terminals. The ''coherent flucton'' model is applied to the distribution of 1 GeV protons on "2"8Si, "3"2S, "4"0Ca, "4"8Ca, "5"8Ni, "2"0"8Pb nuclei. The calculations by the model agree well with experimental data.
Neutron spectra measured in the FFTF In-Reactor Thimble (IRT) by proton recoil proportional counters, proton recoil emulsions, and passive dosimeters have been evaluated and compared with each other and with three-dimensionl diffusion theory calculated spectra for the purpose of validating the passive dosimeter spectrum adjustment technique. The least squares data adjustment code, FERRET, was used to combine measured reaction rates, calculated spectra, and dosimeter cross sections, resulting in adjusted spectra and cross sections with uncertainties and correlations that properly account for uncertainties and correlations on the input parameters.
First measurements of inclusive Z production cross sections in muon and electron decay channels at 7 TeV are presented for proton-proton collisions in the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC). The comparison of the kinematic quantities as well as the studies of selection efficiencies demonstrate a good agreement between simulated events and current data. The measured inclusive cross section for Z($\\gamma^{*}$) production agrees with NNLO QCD cross section calculations and current parton distribution functions.
The damage induced by low-temperature proton irradiation in amorphous Pd/sub 80/Si/sub 20/ prepared by ion implantation is studied via electrical resistivity measurements. Our experimental results concerning the initial damage rate and the resistivity saturation are compared to the results obtained for electron and high energy /sup 16/O irradiation of amorphous Pd/sub 80/Si/sub 20/ quenched from the melt. The resistivity curve is analyzed in terms of irradiation-induced point defects.
The L-subshell and total M-shell X-ray production cross sections of Ta, W, Pt, Au, Pb and Bi have been measured by protons of energy between 0.7 and 2.4 MeV. The obtained results for X-ray production cross sections have been compared with the existing experimental data, prediction of the ECPSSR theory and also with fitted empirical cross sections of Strivay and Weber.
We present recent results obtained in the Toulouse's group that deal with proton to base and nucleoside interactions. We stress the weakness of the sugar part in the nucleoside, i.e. the uridine molecule under scrutiny. Since some parts of the fragmentation spectrum correspond to the fragmentation of a 'pure' uracil molecule, i.e. the RNA base, an 'additivity rule' seems to prevail for the nucleoside, something that still has to be confirmed. Moreover, some results that deal with the secondary electronic emission from uracil are also displayed.
We present results for a complete set of polarization observables for jet production in lepton proton collision, where the final state lepton is not observed. The calculations are carried out in collinear factorization at the level of Born diagrams. For all the observables we also provide numerical estimates for typical kinematics of a potential future Electron Ion Collider. On the basis of this numerical study, the prospects for the transverse single target spin asymmetry are particularly promising. This observable is given by a certain quark-gluon correlation function, which has a direct relation to the transverse momentum dependent Sivers parton distribution.
Atomic L- and M-shell ionization cross sections by protons have been calculated in the plane-wave Born approximation for /sub 79/Au and /sub 92/U with incident energy from 0.1 to 3 MeV with use of relativistic and nonrelativistic Hartree-Slater wave functions. These results are compared with those from the screened hydrogenic model to study the effects of relativity and wave functions. The relativistic and wave-function effects are found to operate in opposite directions. For M/sub 1,2,3/-subshell cross sections, severe cancellations occur between these two factors.
We calculate the electromagnetic form factors of a bound proton. The chiral quark-soliton model provides the quark and antiquark substructure of the proton, which is embedded in nuclear matter. This procedure yields significant modifications of the form factors in the nuclear environment. The sea quarks are almost completely unaffected, and serve to mitigate the valence quark effect. In particular, the ratio of the isoscalar electric to the isovector magnetic form factor decreases by 20% at Q{sup 2}=1 GeV{sup 2} at nuclear density, and we do not see a strong enhancement of the magnetic moment.
PEFP(Proton Engineering Frontier Project) is developing beamlines for various application fields by using the high current 100MeV proton linear accelerator. Beamlines were characterized and categorized by the beam energy, average currents, and irradiation conditions. Among these beamlines the TR104 is designed for the basic science and the research of the aerospace. Before the construction and installation of beamlines, we try to practice and prepare the detail process of installation by the precedent study of TR104 beamline in KAERI site. By this work installation process was checked and confirmed for the same condition of the PEFP site
Energy and angular double-differential cross-section (DDX) data of fragment production reactions by neutrons or protons are very scarce due to experimental difficulties of fragment detection. We adopted a Bragg curve spectrometer (BCS), which is a gridded-ionization chamber that can identify fragments on the basis of the Bragg peak value. We have been developing the BCS for neutron and proton-induced reactions applying the digital waveform analysis technique to obtain better ability of particle discrimination than the analog electronic circuit. (T. Tanaka)
In this work, the chemical transformations induced by 5 keV protons (10{sup 6} ion cm{sup -2}) at the surface of 0.4 {mu}m polyacrylonitrile and polymethacrylonitrile films are analysed by XPS and IRRAS. Spectroscopic changes in both the polymers are globally similar, the most significant feature being a lower relative concentration of nitrogen with respect to carbon closer to the surface. Quantitatively, this change is more marked in the case of polyacrylonitrile which suggests a direct relation with the hydrogen in {alpha} to the nitrile function.
Computational fluid dynamics(CFD) code FLUENT was used to simulate the thermal hydraulic processes occurring in conceptual design of the accelerator-driven subcritical reactor(ADSR) liquid lead target. The purpose of the analysis is to investigate the thermal hydraulic characteristics of liquid lead as ADSR target material with various target geometries and injection locations of proton beam. In the calculation analysis, the local temperature of the liquid lead target rises to the boiling temperature very rapidly. When the proton beam is injected from the bottom of the target system, the duration time to reach the boiling temperature is longer and the temperature distribution is flatter than other cases.
The expected interstellar antiproton spectrum arising from cosmic-ray interactions in the Galaxy is recalculated, and the modulation of both antiprotons and protons is calculated using a two-dimensional modulation model incorporating gradient and curvature drifts and a wavy current sheet as well as the usual diffusion, convection, and energy-loss effects. Significant differences in the antiproton/proton ratio for different solar magnetic field polarities are predicted as well as a 'low-energy' component for antiprotons below about 1 GeV. 28 refs.
The A dependence of cumulative pion production yield cross sections on the basis of the comparison of the data on relative pion yields on Be,C,Al,Ti,Mo and W nuclei at the 159 deg angle laboratory system for the incident proton energy E_0 from 25 to 62 GeV is considered. The regular A dependence on cumulative variable X is noted. The results are compared with the data at E_0< 10 GeV. A possible interpretation of the observed behaviour on the basis of the hypothesis of the flucton mechanism of the pion production in the cumulative region is discussed. 15 refs.; 4 figs.
As the last step of urinary acidification, the inner medullary collecting duct (IMCD) is thought to secrete protons into the tubular lumens by means of a H(+)-translocating adenosinetriphosphatase (H(+)-ATPase). However, recent studies have also shown the existence of Na(+)-H+ exchange activity in IMCD cells. Although the physiological function of the antiporter in IMCD cells is unknown, activation of Na(+)-H+ exchange in other cell-culture systems has been suggested to be closely associated with the process of cell growth. Thus presence of Na(+)-H+ exchange may relate to the growth phase of these cells. To examine intracellular pH (pHi) regulation in growing IMCD cells, we studied proton transport by Na(+)-dependent and Na(+)-independent mechanisms by microfluorimetry using the pHi-sensitive dye 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein acetoxymethyl ester (BCECF/AM). Actively growing cells, defined by (3H)thymidine ...
We briefly reviewed and summarized the experimental study on {beta}-delayed proton decays published by our group over the last 8 years, namely the experimental observation of {beta}-delayed proton decays of nine new nuclides in the rare-earth region near the proton drip line and five nuclides in the mass 90 region with N{approx}Z by utilizing the p-{gamma} coincidence technique in combination with a He-jet tape transport system. In addition, important technical details of the experiments were provided. The experimental results were compared to the theoretical predictions of some nuclear models, resulting in the following conclusions. (1) The experimental half-lives for {sup 85}Mo, {sup 92}Rh, as well as the predicted 'waiting point' nuclei {sup 89}Ru and {sup 93}Pd were 5-10 times longer than the macroscopic-microscopic model predictions of Moeller et al. [At. Data Nucl. Data Tables 66,131(1997)]. These ...
In an attempt to establish a relationship between proton pumping and the photocycle intermediates of bacteriorhodopsin, we have studied the effects of pH and temperature of flash-induced proton pumping and the photointermediates O/sub 640/ and M/sub 412/. The relative quantum yield of flash-induced proton pumping is both pH and temperature dependent. It is high in the acid pH range and at low temperatures but decreases in the basic pH range and at high temperatures. The decay of M/sub 412/ is biphasic. The amplitude of the slowly decaying component (M/sup s/) was found to be pH dependent with a pK similar to that of the ..delta..pH. The pH dependence of the fast-decaying component (M/sup f/) is opposite to that of M/sup s/ and ..delta..pH. Like that of M/sup s/, the amplitude of O/sub 640/ is high in the acid pH range, but unlike the amplitude of M/sup s/, it declines very rapidly at pHs greater than 6.5; the amplitude of ...
The construction of Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences was completed in December 1993. HIMAC consists of an injector linac, two synchrotron rings, a high energy beam transport system and a beam irradiation system. Its accelerator parameters are based on the medical requirement, and helium, carbon, neon, silicon and argon were selected as the accelerated ion species. It has 3 therapy rooms (A{approx}C). Room A has a vertical irradiation system, Room C horizontal and Room B both vertical and horizontal. Two rings can supply beams independently to the vertical and horizontal irradiation systems. Clinical trial started on June 21 1994, after several basic biological and physics experiments lasting about 2 months. Cancer is the top cause of death in Japan since 1981, and people expect good treatment results at HIMAC. Proton and heavy ion radiotherapy has the advantage of dose distribution and biological ...
Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by {sup 10}B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to gain penetration depth in the brain Fairchild proposed, for this purpose, the use of energetic epithermal neutrons at about 10 keV. Phase I/II clinical trials of BNCT for GM are underway at the Brookhaven Medical Research Reactor (BMRR) and at the MIT Reactor, using these nuclear reactors as the source for epithermal neutrons. In light of the limitations of new reactor installations, e.g. cost, safety and licensing, and limited capability for modulating the reactor based neutron beam energy spectra alternative neutron sources are being contemplated for wider implementation of this ...
The experimental study on #beta#-delayed proton decays near the proton drip line published by our group over the last 8 years were reviewed and summarized briefly, including first observation of 9 precursors in the rare-earth region and new measurements of 5 nuclei in the mass-90 region near N-Z line with the aid of the 'p-#gamma#' coincidence in combination with a He-jet tape transport system. Systematically comparing the experimental data with the current nuclear-model predictions, following points were represented. (1) the experimental half-lives for "8"5Mo and "9"2Rh as well as the predicted 'waiting point' nuclei "8"9Ru and "9"3Pd are 5-10 times longer than the macroscopic-microscopic model predictions given by Moeller et al. It considerably influences the prediction of mass abundances of the nuclides produced in rp-process. (2) The current-model predictions are not consistent with the experimental spin-parity assignments of the ...
We briefly reviewed and summarized the experimental study on #beta#-delayed proton decays published by our group over the last 8 years, namely the experimental observation of #beta#-delayed proton decays of nine new nuclides in the rare-earth region near the proton drip line and five nuclides in the mass 90 region with N#approx#Z by utilizing the p-#gamma# coincidence technique in combination with a He-jet tape transport system. In addition, important technical details of the experiments were provided. The experimental results were compared to the theoretical predictions of some nuclear models, resulting in the following conclusions. (1) The experimental half-lives for "8"5Mo, "9"2Rh, as well as the predicted 'waiting point' nuclei "8"9Ru and "9"3Pd were 5-10 times longer than the macroscopic-microscopic model predictions of Moeller et al. [At. Data Nucl. Data Tables 66,131(1997)]. These data considerably influenced the ...
Excitation functions for {sup 201}Pb, {sup 202m}Pb, {sup 203}Pb and {sup 204m}Pb radionuclides which are formed via proton induced reactions with natural thallium target have been measured from their respective threshold (E{sub thr}) to 27.5 MeV using activation technique. Natural copper foils were used to monitor the cyclotron beam. The integral yields (MBq/{mu}A h) of the produced radionuclides were calculated from the measured excitation functions. The optimum proton energy range for the production of {sup 203}Pb with low amount of impurities is (16-10 MeV) after 5 h of EOB. The experimental cross-sections for {sup nat}Tl(p,xn) reactions were compared with the cross-sections recommended by the IAEA and with earlier published data when it was possible. (orig.)
Two-dimensional calculations are performed to obtain the conversion efficiency of traveling wave direct energy convertor adopted in a conceptual design of field reversed configuration D-"3He fusion reactor ARTEMIS. For fusion-born 14.67MeV protons, the efficiency obtained is very small compared with that from one-dimensional analysis. This is because the effective electric field for deceleration of the proton is smaller due to distortion of potentials near girds used to excite the traveling wave and because some fractions of the incident proton beams are inevitably lost to the grids with high energy. To increase the efficiency, the potentials may have to be increased. It seems from the two-dimensional analysis performed here that the conversion efficiency obtainable is less than about 60% with the maximum potential of about 6MV, while the corresponding values from the one-dimensional analysis are about 80% and 1.5MV, ...
This report covers the progress made on the title project for the project period. Four major areas of inquiry are being pursued. Advanced solid state NMR methods are being developed to assay the distribution of the various important functional groups that determine the reactivity of coals. Special attention is being paid to methods that are compatible with the very high magic angle sample spinning rates needed for operation at the high magnetic field strengths available today. Polarization inversion methods utilizing the difference in heat capacities of small groups of spins are particularly promising. Methods combining proton-proton spin diffusion with {sup 13}C CPMAS readout are being developed to determine the connectivity of functional groups in coals in a high sensitivity relay type of experiment. Additional work is aimed at delineating the role of methyl group rotation in the proton NMR relaxation behavior of coals.
We analyse how the structure of the inner curst is influenced by the pairing correlations. The inner-crust matter, formed by nuclear clusters immersed in a superfluid neutron gas and ultra-relativistic electrons, is treated in the Wigner-Seitz approximation. The properties of the Wigner-Seitz cells, i.e., their neutron to proton ratio and their radius at a given baryonic density, are obtained from the energy minimization at beta equilibrium. To obtain the binding energy of baryonic matter we perform Skyrme-HFB calculations with zero-range density-dependent pairing forces of various intensities. We find that the Wigner-Seitz cells have much smaller numbers of protons compared to previous calculations. For the dense cells the binding energy of the configurations with small proton numbers do not converge to a well-defined minimum value which precludes the determination of their structure. We show that for these cells there is ...
The method of proton magnetic resonance (PMR) has been used to study the mechanism of reaction of complexing of paramagnetic Pr/sup 3 +/ ion with ethylenediaminetetra acetic acid (EDTA). The influence of medium acidity (pH5-12), EDTA/Pr ratio varying from 1 to 50, Pr/sup 3 +/ ion concentration (from 5x10/sup -3/ to 3x10/sup -1/ g-ion/l) and temperature (8-98 deg C) on chemical shifts and broadening of signals of EDTA molecule protons is investigated. Data on ratio of components, coordination and stability of forming complexes are obtained. The existence of two types of complexes with the Pr/EDTA ratio equal to 1:1 and 1:2 has been found. Equimolecular complex (1:1) is stable all over the studied temperature interval in contrast to the complex 1:2 for which at 50 deg C fast extrasphere exchange (Pr EDTA)EDTA * + EDTA/sup 0/ reversible (PrEDTA)EDTA/sup 0/ + EDTA * is observed, while at t=98 deg C intrasphere exchange (PrEDTA)EDTA * reversible ...
The authors report that the replacement of Leu-93 in bacteriorhodopsin by Ala (L93A) or Thr (L93T) slows down the photocycle by approximately 100-fold relative to wild-type bacteriorhodopsin. Time-resolved visible absorption spectroscopy and resonance Raman experiments, respectively, show the presence of long-lived O-like and N-like intermediates in the photocycles of the above mutants. We infer the existence of an equilibrium between the N and O intermediates in the photocycles of these mutants. The L93A and L93T mutants exhibit normal proton pumping under continuous illumination, suggesting that the decay of the N and/or O intermediate, and consequently, proton translocation, can be accelerated by the absorption of a second photon. Since the 13-cis----all-trans reisomerization of retinal is completed during the decay of the N and O intermediates, they conclude that the interaction of Leu-93 with retinal is important in this phase of the ...
A new class of hybrid organic-inorganic materials, and methods of synthesis, that can be used as a proton exchange membrane in a direct methanol fuel cell. In contrast with Nafion.RTM. PEM materials, which have random sulfonation, the new class of materials have ordered sulfonation achieved through self-assembly of alternating polyimide segments of different molecular weights comprising, for example, highly sulfonated hydrophilic PDA-DASA polyimide segment alternating with an unsulfonated hydrophobic 6FDA-DAS polyimide segment. An inorganic phase, e.g., 0.5 5 wt % TEOS, can be incorporated in the sulfonated polyimide copolymer to further improve its properties. The new materials exhibit reduced swelling when exposed to water, increased thermal stability, and decreased O.sub.2 and H.sub.2 gas permeability, while retaining proton conductivities similar to Nafion.RTM.. These improved properties may allow direct methanol fuel cells to operate at ...
High spin states of the proton rich nuclei in the mass region A {approx} 100 have been studied at the GASP spectrometer through the evaporation of light charged particles and heavier ions detected in the 4{pi} Si-ball Isis. Rear side injection and pulse shape analysis have allowed a good discrimination among protons, alpha particles and heavy ions up to C. Of the several nuclei populated in the reactions we will discuss here the high spin states of {sup 105} Sn. In addition to an extension of the spherical level, scheme, a regular sequence of dipole transitions has been found, The states of the dipole band are suggested to be built on a neutron h{sup 2}{sub 11/2} excitation coupled to proton particle-hole states, which polarize the core to a slightly prolate shape. The experimental results are in agreement with the prediction of tilted axis cranking calculations, which satisfactorily explain the properties of the band. ...
Sulfonated poly(ether ether ketone) (SPEEK) membranes with various degrees of sulfonation (DS) have been prepared as a potential membrane material for proton exchange membrane by sulfonation process using mixtures of (15-30% concentration) fuming sulfuric acid and (95-98%) concentrated sulfuric acid as the sulfonating agent. The sulfonation process was conducted at room temperature by varying the acid ratio and reaction time. The produced membranes were then characterized by evaluating the ion exchange capacity (IEC), water uptake, thermal stability, proton conductivity and methanol permeability as a function of degree of sulfonation. The proton conductivity of the sulfonated PEEK membranes with various DS was within the magnitude of 10"-"3 and 10"-"2 S cm"-"1 at room temperature and the methanol permeability was in the range of 3.45 x 10"-"7 to 2.73 x 10"-"6 cm"2 s"-"1. The overall membrane performance of the SPEEK ...
The influence of membrane pH gradients on the transbilayer distribution of some common phospholipids has been investigated. The authors demonstrate that the transbilayer equilibrium of the acidic phospholipids egg phosphatidylglycerol (EPG) and egg phosphatidic acid (EPA) can be manipulated by membrane proton gradients, whereas phosphatidylethanolamine, a zwitterionic phospholipid, remains equally distributed between the inner and outer monolayers of large unilamellar vesicles (LUVs). Asymmetry of EPG is examined in detail and demonstrated by employing three independent techniques: ion-exchange chromatography, {sup 13}C NMR, and periodic acid oxidation of the (exterior) EPG headgroup. In the absence of a transmembrane pH gradient ({Delta}pH) EPG is equally distributed between the outer and inner monolayers of LuVs. When vesicles composed of either egg phosphatidylcholine (EPC) or DOPC together with 5 mol % EPG are prepared with a transmembrane {Delta}pH. EPG ...
We present the strategy which has been used recently to optimize integrated luminosity at the Fermilab Tevatron proton-antiproton collider. We use a relatively simple model where we keep the proton intensity fixed, use parameters from fits to the luminosity decay of recent stores as a function of initial antiproton intensity (stash size), and vary the stash size to optimize the integrated luminosity per week. The model assumes a fixed rate of antiproton production, that a store is terminated as soon as the target stash size for the next store is reached, and that the only downtime is due to store turn-around time. An optimal range of stash sizes is predicted. Since the start of Tevatron operations based on this procedure, we have seen an improvement of approximately 35% in integrated luminosity. Other recent operational improvements have been achieved by decreasing the shot-setup time and by reducing beam-beam effects by making the ...
A KEK-PS experiment E337 `Angular correlation of intermediate mass fragments emitted from the target multifragmentation reactions with 12 GeV protons` is an extension of the E288 performed a few years ago. The E288 revealed that the proton-induced target multifragmentation reactions at 12 GeV showed quite interesting phenomena such as 70 degree peaking angular distributions for intermediate mass fragments. In December, 1955, the test experiment with 12 GeV protons was started at KEK using this newly constructed counter array of 37 Bragg Curve Counters. The main production experiment was performed in April and May in 1996 after debugging the new counter system and DAQ system, as well as EP1-B beam line. Data with Au, Tm, Sm and Ag targets were successfully accumulated. The data are in the analysis stage, and several interesting features of high energy nuclear reactions have already been seen. (G.K.)
Precise measurements of the single spin asymmetry AN, and the double spin asymmetry ANN, in proton-proton (pp) elastic scattering in the region of four-momentum transfer squared 0.0012 have been performed using a polarized atomic hydrogen gas jet target and the Relativistic Heavy Ion Collider (RHIC) polarized proton beam. We present measurements of AN and ANN at center-of-mass energies ?(s)=6.8 and 13.7 GeV. These spin-dependent observables are sensitive to the poorly known hadronic spin-dependent amplitudes. Comparing AN at different energies, a ?(s) dependence of the hadronic single spin-flip amplitude is suggested. A hadronic double spin-flip amplitude from the ANN data is consistent with zero within a 2-? level. We also present ??T, estimated from the measured ANN data. The results for ??T are consistent with zero. Our results provide significant constraints toward a comprehensive understanding of the reaction mechanism for pp elastic ...
Anti-proton and positron Galactic cosmic ray (GCR) spectra are among the key targets for indirect detection of dark matter (DM). The boost factors, corresponding to an enhancement of the signal|linked to the clumpiness properties of the dark matter distribution|, have been taken as high as thousands in the past. The dramatic impact of these boost factors for indirect detection of antiparticles, for instance with the PAMELA satellite or the coming AMS-02 experiment, asks for their detailed calculation. We take into account the state-of-the-art results of high resolution N-body dark matter simulations to calculate the most likely energy dependent boost factors|linked to the GCR propagation properties|, for anti-protons and positrons. The results from extreme, but still possible, configurations of the clumpy dark matter component is also discussed. Starting from the mass and space distributions of sub-halos, the anti-proton ...
(abridged) Observations clearly show that low-mass AGB stars can provide a nucleosynthesis site of the s-process. Recent stellar evolution models indicate that radiative burning of C13 between thermal pulses in low-mass AGB stars may indeed provide the needed neutrons. Some mixing between the proton-rich envelope and the carbon-rich core may lead to the production of C13. However, the responsible physical mechanism is not yet unambiguously identified. We present stellar model calculations with overshoot and rotation. Overshoot, with a time-dependent and exponentially decaying efficiency, leads to a partial mixture of protons and C12 during the third dredge-up. According to the depth-dependent ratio of protons and C12, a small C13-pocket forms underneath a N14-rich layer. Overshoot does not allow for any mixing during the interpulse phase. Rotation introduces mixing driven by large angular velocity gradients which form at ...
When quantum molecular dynamics (QMD) is applied to the nuclear reactions in theory of relativity region, a number of problems arise, and in order to solve them, the prescription of the extension of ordinary nonrelativistic QMD is introduced, and the analysis of proton incidence reaction by using it is shown. By introducing the interaction corresponding to Lorentz transformation, the problems were solved. QMD is the semiclassical simulation that treats the motion of nucleons represented by Gauss wave packet. The motion of wave packet center is expressed by Newton equations and two-nucleon collision. The introduction of the interaction corresponding to Lorentz transformation is explained. As the result of the introduction, through the relative distance of two particles, the interaction becomes to depend on momentum. The phase distribution function of one body corresponding to Lorentz transformation is used for calculating the final state Pauli effect of collision ...
Measurements of PEM fuel cell device performance were made with different gas inlet temperatures and relative humidity using a newly-designed test fixture. Significant improvement in device performance was observed when the fuel inlet temperature was increased above the operating temperature of the cell. These measurements were then correlated to a model to describe energy and mass transport processes. Proton exchange membrane (PEM), fuel cells--the focus of this study--use an ion conducting polymer, especially polyperfluorosulfonic acid materials. These polymer materials, when imbibed with water, exhibit solution-like properties, but because the anions are chemically bound to the polymeric structure, the electrolyte is contained. Importantly, product water removal is simplified, as electrolyte dilution is not a concern. However, the proton transport rate is a function of the polymer geometry, which is set, in part, by the polymer water ...
Background: the authors report on the conception and first clinical application of a donut-shaped high-dose configuration for proton therapy (PT). This approach allows one to intensify target volume dose coverage for targets encompassing a critical, dose-limiting structure - like here, the cauda equina -, whilst delivering minimal dose to other healthy structures surrounding the target, thereby reducing the integral dose. Methods and results: intensity-modulated PT methods (IMPT) for spot scanning were applied to create and deliver a donut-shaped high-dose configuration with protons, allowing treating > 75% of the target with at least 95% of the prescribed dose of 72.8 CGE, whilst restricting dose to the cauda equina to 60-65 CGE. Integral dose was lower by a factor of 3.3 as compared to intensity-modulated radiotherapy with photons (IMXT). Conclusion: IMPT and spot scanning technology allow a potentially clinically useful approach which ...
Background: the authors report on the conception and first clinical application of a donut-shaped high-dose configuration for proton therapy (PT). This approach allows one to intensify target volume dose coverage for targets encompassing a critical, dose-limiting structure - like here, the cauda equina -, whilst delivering minimal dose to other healthy structures surrounding the target, thereby reducing the integral dose. Methods and results: intensity-modulated PT methods (IMPT) for spot scanning were applied to create and deliver a donut-shaped high-dose configuration with protons, allowing treating > 75% of the target with at least 95% of the prescribed dose of 72.8 CGE, whilst restricting dose to the cauda equina to 60-65 CGE. Integral dose was lower by a factor of 3.3 as compared to intensity-modulated radiotherapy with photons (IMXT). Conclusion: IMPT and spot scanning technology allow a potentially clinically useful approach which is ...
In this work we develop a new propagation model for the Galactic cosmic rays based on the GALPROP code, including contributions from dark matter annihilation. The model predicts compatible Galactic diffuse $\\gamma$ ray spectra with EGRET data in all sky regions. It also gives consistent results of the diffuse $\\gamma$ ray longitude and latitude distributions. Further the results for B/C, $^{10}$Be/$^9$Be, proton, electron and antiproton spectra are also consistent with cosmic ray measurements. In the model we have taken a universal proton spectrum throughout the Galaxy without introducing large fluctuation for the proton energy loss is negligible. The dark matter annihilation signals are `boosted' after taking the contribution from subhalos into account. Another interesting feature of the model is that it gives better description of the diffuse $\\gamma$ rays when taking the source distribution compatible with supernova ...
The polarization of extracted SATURNE II proton beam as a function of different ion source configurations was studied. Two distinct experiments were necessary for this purpose. In the first one, the left-right instrumental asymmetry of the beam polarimeter was determined using an unpolarized beam. In the second one this correction factor was applied to asymmetries measured with the beam from the polarized ion source in all polarization states. The measurements were carried out at the proton beam kinetic energy 0.80 GeV, where the pp-elastic scattering analyzing power is near its maximum. The results confirmed that the two so-called ``unpolarized states`` of the source were polarized to several percent, whereas the absolute values of the beam polarizations in the so-called ``polarized states`` were equal and opposite. It was observed that the hexapole lens of the ion source produced beam polarization in the absence of any transition. The beam ...
The CMS detector (Compact Muon Solenoid) is under construction at one of the four proton-proton interaction points of the LHC (Large Hadron Collider) at CERN, the European Organization for Nuclear Research (Geneva, Switzerland). The inner tracking system of the CMS experiment consisting of silicon detectors will have a diameter of 2.4 m and a length of 5.4 m representing the largest silicon tracker ever. About 15000 silicon strip modules create an active silicon area of 200 m2 to detect charged particles from proton collisions. They are placed on a rigid carbon fibre structure, providing stability within the working conditions of a 4 T solenoid magnetic field at ?10oC. Knowledge of the position of the silicon detectors at the level of 100 ?m is needed for an efficient pattern recognition of charged particle tracks. Metrology methods are used to survey tracker subdetectors and the integrated Laser Alignment System (LAS) provides absolute ...
A new measurement of the cosmic ray antiproton-to-proton flux ratio between 1 and 100 GeV is presented. The results were obtained with the PAMELA experiment, which was launched into low-earth orbit on-board the Resurs-DK1 satellite on June 15th 2006. PAMELA is equipped with a silicon-microstrip magnetic spectrometer and a silicon-tungsten imaging calorimeter and has been collecting data since July 2006. During 500 days of data collection a total of about 1000 antiprotons have been identified, including 100 above an energy of 20 GeV. The high-energy results are a ten-fold improvement in statistics with respect to all previously published data. The antiproton-to-proton flux ratio increases smoothly with energy up to about 10 GeV, in agreement with previous experiments, and then levels off. The data follow the trend expected from secondary production calculations and significantly constrain contributions from exotic sources, e.g. dark matter ...
A preliminary chemical characterization is presented of phosphate-free aminolipids isolation from Chlorobium limicola f. thiosulfatophilum. The lipid contains no phosphorus, glycerol, sugar, ornithine, or lysine. Ultraviolet absorption and fluorescence spectra indicate that the amino moiety of the lipid is an aromatic heterocyclic compound. Infrared spectra indicate that the lipid is a secondary or tertiary amide, and gas chromatograhic analysis of the hydrolyzed lipid shows that for each 1100 g of lipid, 1 mol of myristic acid (C/sub 14:0/) is linked in an amide bond. Acid hydrolysis of the lipid yields two fluorescent substances, A (ninhydrine positive) and B (negative), in addition to myristic acid. Proton nuclear magnetic resonance (NMR) studies indicate that substance A contains a butyl groups attached to a conjugated ring carbon, two equivalent ethyl groups attached to one or two nitrogen atoms, and two downfield protons (8.4 ppm), ...
The Neutron Science Project at Japan Atomic Energy Research Institute has been proposed for the research of nuclear transmutation technology and the basic science with a spallation neutron source. The project calls for an 8MW proton linac which accelerates 5.3mA average current cw and pulsed beams up to 1.5GeV. The superconducting (SC) rf-cavity is the main option for the energy part from 100MeV to 1.5GeV because by using the SC structure, less power is consumed in cw operation than by using a normal conducting (NC) structure. A conceptual design study of the superconducting proton linac is reported. The SC linac is composed of 8 {beta} sections. Each section has the identical 5-cell cavities with the surface peak field of 16MV/m. The total number of cavities is 284, and the length of the SC linac is 690m. The lattice design is determined with the equipartitioned condition and the matched envelope equations for the minimum emittance growth. The ...
Gantries in the proton/carbon cancer therapy machines represent the major cost and are of the largest size. This report explains a new way to the gantry design. The size and cost of the gantries are reduced and their use is simplified by using the fixed magnetic field. The ''new'' gantry is made of a very large momentum acceptance non-scaling Fixed Field Alternating Gradient (FFAG) quarter and half arc beam lines. The gantry is made of combined function magnets with a very strong focusing and small dispersion function. Additional magnets with a fast response are required to allow adjustments of the beam position for different energies at the beginning of the gantry. Additional strong focusing magnets following the gantry have also to be adjustable to provide required spot size and radial scanning above the patients. The fixed field combined function magnets could be made of small permanent magnets for the ...
A novel compact CT-guided intensity modulated proton radiotherapy (IMPT) system is described. The system is being designed to deliver fast IMPT so that larger target volumes and motion management can be accomplished. The system will be ideal for large and complex target volumes in young patients. The basis of the design is the dielectric wall accelerator (DWA) system being developed at the Lawrence Livermore National Laboratory (LLNL). The DWA uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. High electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The system will produce individual pulses that can be varied in intensity, energy and spot width. The IMPT planning system will optimize delivery characteristics. The system will be capable of being sited in a conventional linac vault and provide intensity ...
PAMELA is a satellite borne experiment designed to study with great accuracy cosmic rays of galactic, solar, and trapped nature in a wide energy range (protons: 80 MeV-700 GeV, electrons 50 MeV-400 GeV). Main objective is the study of the antimatter component: antiprotons (80 MeV-190 GeV), positrons (50 MeV-270 GeV) and search for antinuclei with a precision of the order of $10^{-8}$). The experiment, housed on board the Russian Resurs-DK1 satellite, was launched on June, $15^{th}$ 2006 in a $350\\times 600 km$ orbit with an inclination of 70 degrees. In this work we describe the scientific objectives and the performance of PAMELA in its first two years of operation. Data on protons of trapped, secondary and galactic nature - as well as measurements of the December $13^{th}$ 2006 Solar Particle Event - are also provided.
The superconducting Tevatron accelerator at Fermi National Accelerator Laboratory (Fermilab) has surpassed twenty years of operation. The Tevatron is still the highest energy particle accelerator in the world and will remain so until the commissioning of the LHC in Europe later this decade. The Tevatron has operated in a Fixed Target mode, accelerating a proton beam into stationary targets/detectors, as well as a Colliding Beam mode, continuously colliding counter rotating beams of protons and antiprotons. Upon completion, the Tevatron cryogenic system became the world's largest helium refrigeration system. In 1993, the Tevatron cryogenic system was given the designation of International Historic Mechanical Engineering Landmark by the American Society of Mechanical Engineers. The operational history, experiences and statistics of the Tevatron, with an emphasis on the cryogenic system, is presented. Improvements, upgrades and current ...
The Tevatron is a proton anti-proton accelerator collider operating at the Fermi National Accelerator Laboratory. The machine is currently delivering beam for the CDF and D0 experiments, which expect increasing luminosity until the conclusion of Run II, planned for 2009. The Laboratory defined a plan for achieving higher luminosity, and one of the tasks is the upgrade of the accelerator's beam position monitor (BPM). The Tevatron was built during the early eighties and some of its control systems, including the BPMs, are still the original ones. This paper describes the front-end software of the Tevatron BPM upgrade, from the requirements to the implementation, and the underlying hardware setup. The front-end software designed is presented, emphasizing its modularity and reusability, allowing it to be applied to other Fermilab machines.
A method, based on anion exchange chromatography, is presented for the isolation of "1"3"9Ce after production by a proton-induced nuclear reaction on a thick praseodymium target. After bombardment the target is dissolved in nitric acid and "1"3"9Ce oxidised to the Ce(IV) oxidation state with bromic acid. "1"3"9Ce is then separated form the praseodymium by anion exchange chromatography on a Ag MP-1 resin column in a nitric acid - bromic acid mixture. "1"3"9Ce is sorbed onto the resin column and praseodymium eluted with the acid mixture. The bromic acid is washed out of the column with nitric acid and "1"3"9Ce finally eluted with dilute nitric acid containing sulphur dioxide.
Neopentane, because of its unique structural features, was found to be a useful probe for the assay of the acidity of various zeolites. The C-C bond was attacked by catalyst protons yielding CH/sub 4/ and the isobutyl carbenium ion in equal quantities. The latter either decomposed to produce isobutene or underwent secondary reactions. New avenues for reaction were opened with isobutane. The reaction of the Bronsted protons with the tertiary CH bonds produced H/sub 2/ and the same isobutyl carbenium ion. Hydride ion transfer of the same tertiary hydrogen to existing carbenium ions also occurred and the results showed that about half of the reaction was carried by this pathway. As with Neopentane, the C-C bond could also be attacked yielding the sec-propyl carbenium ion. These tools are being further developed.
We report here results of an application of single-nucleon stripping reactions at high energies (65 MeV/u) in inverse kinematics to obtain spectroscopic factors. From measurements of the partial cross-sections for ground and excited states in residual nuclei formed in one-proton stripping reactions, single particle orbits and occupancies of light nuclei have been studied in the s-d shell. Single proton stripping cross-sections of {sup 25}Al and {sup 26,27,28}P on a Be target have been measured using the S800 spectrograph and the NaI(Tl) array at the NSCL. These results indicate that this technique may provide a general tool for the intermediate energy range analogous to transfer (pick-up) reactions at low-energy.
We report here results of an application of single-nucleon stripping reactions at high energies (65 MeV/u) in inverse kinematics to obtain spectroscopic factors. From measurements of the partial cross-sections for ground and excited states in residual nuclei formed in one-proton stripping reactions, single particle orbits and occupancies of light nuclei have been studied in the s-d shell. Single proton stripping cross-sections of "2"5Al and "2"6","2"7","2"8P on a Be target have been measured using the S800 spectrograph and the NaI(Tl) array at the NSCL. These results indicate that this technique may provide a general tool for the intermediate energy range analogous to transfer (pick-up) reactions at low-energy.
The dielectric wall accelerator (DWA) system being developed at the Lawrence Livermore National Laboratory (LLNL) uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. High electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The system is capable of accelerating any charge to mass ratio particle. Applications of high gradient proton and electron versions of this accelerator will be discussed. The status of the developmental new technologies that make the compact system possible will be reviewed. These include, high gradient vacuum insulators, solid dielectric materials, photoconductive switches and compact proton sources.
The ATLAS High Level Trigger (HLT) is a distributed real-time software system that performs the final online selection of events produced during proton-proton collisions at the Large Hadron Collider (LHC). It is designed as a two-stage trigger and event filter running on a farm of commodity PC hardware. Currently the system consists of about 850 processing nodes and will be extended incrementally following the expected increase in luminosity of the LHC to about 2000 nodes. The event selection within the HLT applications is carried out by specialized reconstruction algorithms. The selection can be controlled via properties that are stored in a central database and are retrieved at the startup of the HLT processes, which then usually run continuously for many hours. To be able to respond to changes in the LHC beam conditions, it is essential that the algorithms can be re-configured without disrupting data taking while ensuring a consistent and reproducible ...
I present an overview of the measurement of the proton form factors in the time-like regiun. BABAR has recently measured with great accuracy the e{sup +} e{sup -} {yields} p p-bar reaction from productiun threshold up to an energy of {approx} 4.5 GeV; finding evidence for a ratio of the electric to magnetic form factur greater than unity, contrary to expectation. In agreement with previous measurements. BABAR confirmed the steep rise uf the magnetic form factor close to the p p-bar mass threshold, suggesting the possible presence of an under-threshuld N N-bar vector state. These and uther open questiuns related to the nucleon furm factors both in the time-like and space-like region, wait for more data with different experimental techniques to be possibly solved.
Gas nitridation has shown excellent promise to form dense, electrically conductive and corrosion-resistant Cr-nitride surface layers on Ni-Cr base alloys for use as proton exchange membrane fuel cell (PEMFC) bipolar plates. Due to the high cost of nickel, Fe-base bipolar plate alloys are needed to meet the cost targets for many PEMFC applications. Unfortunately, nitridation of Fe-base stainless steel alloys typically leads to internal Cr-nitride precipitation rather than the desired protective surface nitride layer formation, due to the high permeability of nitrogen in these alloys. This paper reports the finding that it is possible to form a continuous, protective Cr-nitride (CrN and Cr2N) surface layer through nitridation of Fe-base stainless steel alloys. The key to form a protective Cr...
The radioisotope production facilities and programs of the 86-Inch Cyclotron are reviewed in this presentation. The 86-Inch Cyclotron is designed to accelerate protons to a maximum energy of 22 MeV for internal targets. These protons are used to bombard metals that are electroplated, potted or soldered to water-cooled plates. Additionally, metals and inorganic compounds are bombarded in water-cooled tube targets. High radioisotope production rates are obtained by beam currents as large as 3 mA. Production rates for /sup 11/C, /sup 57/Co, /sup 67/Ga, /sup 68/Ge, /sup 109/Cd, and other isotopes are presented. The production of /sup 11/C for the carboxyl labeling of amino acids in cooperation with Oak Ridge Associated Universities is discussed. The 86-Inch Cyclotron is used for those programs requiring a larger beam current than is available from commercial cyclotrons.
Abstract The electrochemical properties of a perfluorosulfonic acid (PFSA) membrane are estimated using a combination of molecular dynamics simulation and statistical thermodynamic model. We obtain all parameters in an ionic conductivity model from an atomistic simulation and remove all adjusted model parameters. From a microscopic point of view, the hydrated PFSA membrane shows micro-phase segregation which separated into hydrophilic and hydrophobic phases. Our present work originates with this phenomenon and we treat this phase segregation as if it is a continuous phase for each of which the proton (H+) is transported inside the PFSA membrane/solvent (water and alcohols) mixture. The chemical potential for a given system is estimated using a molecular simulation technique to predict the ...
This work deals with a new route to modify polymer blend morphology in order to improve the porosity of gas diffusion layers (GDLs) for proton exchange membrane fuel cells (PEMFCs). First, electrically conductive polymer-based blends were carefully formulated using a twin-screw extrusion process. Blend electrical conductivity was ensured by the addition of high specific surface area carbon black and synthetic graphite flakes. Final GDL porosity, in particular its macroporosity, was generated by melt blending polyamide 11 (PA11) matrix with polystyrene (PS) followed by PS extraction with tetrahydrofuran (THF) solvent at room temperature. In order to improve GDL porosity by the optimisation of PS dispersion in the PA11 matrix, PA11/PS blends were compatibilised by the addition of 2 wt.-% of ...
The fully depleted pn-junction charge coupled device (pn-CCD) has been developed as a detector for X-ray imaging and high-resolution spectroscopy for the X-ray satellite missions XMM and ABRIXAS. If the detector is exposed to a particle radiation environment, the energy resolution is degraded due to charge transfer losses and a dark current increase. In a first experiment, prototype devices were irradiated with 10 MeV protons. After completion of the detector development, the proton irradiation was repeated for a quantitative study of the radiation damage, relevant for the satellite missions. The irradiation test was extended by a 5.5 MeV {alpha}-particle and a 6 keV X-ray exposure of the pn-CCD, including the CAMEX preamplifier chip.
Elastic scattering cross sections of keV protons in solids (Z=3-82) are calculated using the partial wave expansion technique and the ''muffin-tin'' bound-atom potential. The differential cross sections for small scattering angles of less than 10deg are smaller than those with the Ziegler-Biersack-Littmark potential at all energies and for all solids, although, for larger angles, the two cross sections agree with each other. The mean free paths of the protons in the solids, obtained from the total cross sections, decrease very slowly with decreasing energy. Furthermore, at low energies they approach half the nearest-neighbor distance, which is taken as the radius of the augmented plane wave sphere in the muffin-tin model of crystalline solids. (orig.).
A newly developed method to support tissue characterization in routine MR imaging is presented. It represents a compromise between the practical requirements of clinical routine (short measurement time, multisection imaging) and the necessary accuracy of the relaxation parameter evaluation. The sequence employed is a modification of the PHAPS technique and works with two excitation pulses. It allows the simultaneous acquisition of all measurement data for the subsequent T1, T2, and rho evaluations. T1 is determined with a specially designed computation formula based on four signal ratios. A multiexponential T2 analysis is performed with use of 28 echoes. From these parameters, relative proton density can be computed.
Differential cross sections for the excitation of the first octupole-vibrational state in the closed-neutron-shell nuclides "8"8Sr and "9"0Zr and in the closed-proton shell-nuclei sup(116,118,120,124)Sn by 11 MeV neutrons are presented. The distorted-wave Born approximation is used to obtain deformation lengths, delta(3"-) for each state. Results are compared with earlier measurements of inelastic proton scattering to the same states. Although limited resolution in the neutron time-of-flight spectrometer complicates the interpretation of the Sn data, the overall conclusion that deltasub(nn')(3"-) approx. deltasub(pp')(3"-) is supported by all of the measurements. (orig.).
The Pulsed Lepton Source (PLS) project opens some exciting possibilities for muon and neutrino physics . The PLS would use the 0.25 4s proton pulses from the upgraded Proton Storage Ring (PSR) at LAMPF to create short, intense bursts of muons and neutrinos. The neutrino beam would be used for a few fundamentally important weak interaction physics experiments. The muon beams would find a wide variety of applications in both fundamental and applied'' muon physics areas. After a brief discussion of the physical layouts of the PSR and the proposed PLS in Sec. 2 and muon area in Sec. 3, we note some of the muon physics experiments and areas that could advantageously be addressed at the PLS in Secs. 4 and 5, and conclude in Sec. 6.
The effects of spin diffusion on the free induction decay (FID) of protons associated with the noncrystalline domains of two polymers, polyethylene and blended Nylon 66 (ZYTEL-408), have been examined using Goldman--Shen NMR pulse sequence ((1/2)..pi..x-t/sub 0/-(1/2)..pi..x-bar-tau-(1/2)..pi..x-t). At tau< or approx. =100 ..mu..s, the FID is drastically distorted from the exponential form while at longer tau(tau> or approx. =500 ..mu..s) an exponential FID is observed; but its transverse spin relaxation rate is smaller than that of the FID obtained after a single (1/2)..pi..x pulse and approaches this value at the limit of large tau. These findings are interpreted in terms of the theory of rapid spin diffusion. The spatial variation in the spin relaxation rate within the noncrystalline domain is inferred.
An all solid-state kicker pulser for a proton radiography system has been designed. Multiple solid-state modulators stacked in an inductive-adder configuration are utilized in this kicker pulser design. Each modulator is comprised of multiple metal-oxide-semiconductor field-effect transistors (MOSFETs) which quickly switch the energy storage capacitors across a magnetic induction core. Metglas is used as the core material to minimize loss. Voltage from each modulator is inductively added by a voltage summing stalk. A circuit model of a prototype inductive adder kicker pulser modulator has been developed to predict the performance of the pulser modulator. The modeling results are compared with experimental data.
Differential scattering experiments are reported for proton impact on N_2, CO, and NO in the energy range E/sub lab/=30--80 eV. The measurements include the range of very small scattering angles around 0"0 as well as the rainbow region. The vibrationally resolved energy-loss spectra show a relatively low vibrational inelasticity for all three systems. Differential cross sections, transition probabilities, and the mean vibrational energy transfer are presented. Rotational excitation is indicated by the broadening of the energy-loss peaks which is most significant for H"+--NO. The small-angle scattering data for vibrational excitation in CO show good agreement with the impact parameter theory using the known long-range interactions for this system.
The total photoabsorption cross section on a free proton was measured at the GRAAL facility in the energy range E ? = 600?1500 MeV. The large-aperture LAGRAN?E detector and a liquid hydrogen target were used in the experiment performed with a back-scattered Compton gamma beam. To improve the accuracy, two alternative methods were employed. First, a subtraction method of using empty-target measurements allowed the cross section ? tot to be evaluated directly because of a low level of the electromagnetic background. Second, an algorithm for evaluating ? tot on the basis of summing the dominating partial cross sections was developed. Experimental results obtained for ? tot by the two methods are compared with existing data.
The photon-proton total cross section has been measured in the process e{sup +}p{yields}e{sup +}{gamma}p{yields}e{sup +}X with the ZEUS detector at HERA. Events were collected with photon virtuality Q{sup 2}<0.02 GeV{sup 2} and average {gamma}p center-of-mass energy W{sub {gamma}}{sub p}=209 GeV in a dedicated run, designed to control systematic effects, with an integrated luminosity of 49 nb{sup -1}. The measured total cross section is {sigma}{sub tot}{sup {gamma}}{sup p}=174{+-}1 (stat.){+-}13 (syst.) {mu}b. The energy dependence of the cross section is compatible with parameterizations of high-energy pp and pp-bar data.
In this work, a three-dimensional multiphase non-isothermal model incorporated with a capillary-extended sub-model in gas channels is used to investigate the coupled phenomena of water and thermal transport in proton exchange membrane fuel cells. Distributions of water and temperature along the flow path in the channel are highlighted and the pros and cons of various operating temperatures are elaborated. In addition, this work also sheds light on the impacts of temperature variations of bipolar plates induced by non-uniform cooling conditions, which have been overlooked by most previous works. An important phenomenon of water distribution, dry-out at inlets and flooding at outlets (DIFO), is observed and this non-uniform distribution is revealed to be greatly influenced by the operating t...
This progress report concerns work completed or initiated since our last report in October of 1980. We have performed experiments in two major areas: photodissociation of organic cations to study the competition between isomerization and fragmentation; and, low energy proton transfer reactions of HCO"+ with selected neutrals. The former area provides a sideline to our combustion studies of proton transfer in hydrocarbon flames, but the question of energy transfer in highly excited gas phase ions impacts directly upon questions closely related to the fate of ions in combustion. The latter area, currently in progress, focuses upon the dynamics of biomolecular reactions of direct relevance to combustion.
Thick targets of several heavy lanthanide (Ho-Lu) compounds were bombarded by protons and "3He ions of 3 MeV/amu, and M_#alpha# and M_#beta# X-rays were measured with a crystal spectrometer. Ionization probabilities of the N-shell for zero impact parameter were obtained from the X-ray intensity ratio for proton and "3He ion impacts. A shell dependence of the ionization probability was found in a scaling plot. X-ray spectra of lanthanide compounds were compared and no chemical effect was observed. This result is considered to be due to the fact that the main component of M_#alpha# and M_#beta# lines is for radiative transition after the refilling of the 4f orbit (3d"-"14f"n"+"1 #-># 4f"n) where n denotes the number of 4f electrons of the target atom before ionization. (orig.).
The complete world set of parity-violating electron scattering data up to Q{sup 2}{approx}0.3 GeV{sup 2} is analyzed. We extract the current experimental determination of the strange electric and magnetic form factors of the proton, as well as the weak axial form factors of the proton and neutron, at Q{sup 2}=0.1 GeV{sup 2}. Within experimental uncertainties, we find that the strange form factors are consistent with zero, as are the anapole contributions to the axial form factors. Nevertheless, the correlation between the strange and anapole contributions suggest that there is only a small probability that these form factors all vanish simultaneously.
We have developed an energy-extension method of a Bragg curve counter (BCC) at the high-energy end for the measurements of double-differential cross-sections (DDXs) of fragment productions induced by tens of MeV protons. In this method, we estimate the incident energies of the fragments penetrating a BCC on the basis of the energy loss and atomic number (Z). We applied this method to the DDX measurements of the {sup nat}C(p, Li) and {sup nat}C(p, Be) reactions induced by 70 MeV protons. The validity of this method has been confirmed by comparing the DDXs of beryllium with theoretical predictions of the PHITS code and the two-body kinematics. This method improves the energy acceptance of the BCC for light fragments twice as wide as that of a conventional method without remodeling of the BCC and any loss of the original advantages.
An apparatus for non-invasively inspecting an object, such as an item of luggage, for explosives material is described. It comprises a multi-channel thermal neutron inspection system having a plurality of neutron irradiation chambers. Simultaneous operation of several channels increases the maximum system throughput several times. Each chamber has a lithium neutron source which is stimulated to neutron production by a proton beam. Beam switching magnets are energised by pulsing to divert a common proton beam to each source in turn. The initial beam is generated by a radio frequency quadrupole accelerator. The advantages of this system are very low residual source activity and controllable neutron production thereby minimising safety hazards. The irradiation chamber may contain several different gamma ray detectors to identify the elements present in explosives material. In addition, a neutron radiography imaging means may be employed to ...
The exclusive electroproduction of ?0 mesons was studied with the HERMES spectrometer at the DESY laboratory by scattering 27.6 GeV positron and electron beams off a transversely polarized hydrogen target. Spin density matrix elements for this process were determined from the measured production- and decay-angle distributions of the produced ?0 mesons. These matrix elements embody information on helicity transfer and the validity of s-channel helicity conservation in the case of a transversely polarized target. From the spin density matrix elements, the leading-twist term in the single-spin asymmetry was calculated separately for longitudinally and transversely polarized ?0 mesons. Neglecting s-channel helicity changing matrix elements, results for the former can be compared to calculations based on generalized parton distributions, which are sensitive to the contribution of the total angular momentum of the quarks to the proton spin.
The high selectivity of 201 MeV inelastic proton scattering at forward angles for exciting ..delta..L=0 spin flip transitions is outlined by comparison with (e,e') and 65 MeV (p,p') measurements. A summary of the results obtained on the calcium isotopes, the N=28 isotones, /sup 88/Sr and /sup 90/Zr is presented. The differences in the relative M1 strength distributions between the (p,p') and the (e,e') results are discussed. Preliminary results on /sup 208/Pb are given; the ''isoscalar'' 1/sup +/ state at 5.846 MeV is excited.
Proton induced X-ray emission (PIXE) and proton induced {gamma}-ray emission (PIGE) techniques are employed for the determination of essential and trace elements in some commonly used medicinal plants of north east India. Light elements such as Na, Mg, Al and P are determined by PIGE while medium Z elements such as K, Ca, Mn, Fe, Cu, Zn, Rb and Sr are determined by PIXE. Analysis is performed on pellets (thick targets) prepared using powders of the specimens which, in turn, are obtained following a series of processing steps. Plant based biological certified reference materials (CRMs) served as standards for quantification. These elements are found to be present in varying concentrations in the studied plants, with the contents of Mn and Zn being notably large in certain specimens. Medicinal properties possessed by these plants have been correlated with their elemental distribution.
An electrochemistry model was developed to analyse the J-V characteristics of a Proton Exchange Membrane (PEM) water electrolyzer for hydrogen production. The Butler-Volmer equation and water transport characteristics through electrolyte membrane were employed to simulate the electrode activation over-potential and membrane ohmic over-potential, respectively. The modeling results are found to agree reasonably well with experimental data published in the literature. The parametric simulations show that the ohmic over-potential is relatively small with typical water content in the membrane. Compared with the cathode over-potential, the anode over-potential is more significant and constitutes the major source of voltage loss. The high anode over-potential is due to the relatively slow oxidation kinetics, which is related to anode material property and microstructure. This model can be integrated with a photovoltaic or wind turbine model to predict the performance of ...
A compact proton accelerator for medical applications is being developed at Lawrence Livermore National Laboratory. The accelerator architecture is based on the dielectric wall accelerator (DWA) concept. One critical area to consider is the switch region. Electric field simulations and thermal calculations of the switch area were performed to help determine the operating limits of rmed SiC switches. Different geometries were considered for the field simulation including the shape of the thin Indium solder meniscus between the electrodes and SiC. Electric field simulations were also utilized to demonstrate how the field stress could be reduced. Both transient and steady steady-state thermal simulations were analyzed to find the average power capability of the switches.
Two perfluorosulfonic acid membranes, Nafion{sup R} 105 and Nafion{sup R} 115 with the same thickness but different equivalent weights (EW = 1000 g/eq. resp. 1100 g/eq.) were characterised by conductivity measurements at different water vapour activities in the temperature range of 25-70{sup o}C. The results demonstrate that a lower membrane equivalent weight opens the possibility to obtain the needed proton conductivity at lower water vapour activity. This is especially important for those fuel cell applications, in which the cell is operated without external humidification of the fuel gases. (author) 5 figs., 5 refs.
The formation constants of species formed in the system H"+"+alanine and VO_"2"+alanine have be determined in aqueous solution for 1.0protonation constant of the amino group of alanine has been determined using a computer program which employ a least-squares method. The defence of the protonation of alanine and the stability constant of the species on ionic strength are described by a Debby-huckel type equation.
Energy flows in deep inelastic electron-proton scattering are investigated at a centre-of-mass energy of 296 GeV for the range Q{sup 2}{>=}10 GeV{sup 2} using the ZEUS detector. A comparison is made between events with and without a large rapidity gap between the hadronic system and the proton direction. The energy flows, corrected for detector acceptance and resolution, are shown for these two classes of events in both the HERA laboratory frame and the Breit frame. From the differences in the shapes of these energy flows we conclude that QCD radiation is suppressed in the large-rapidity-gap events compared to the events without a large rapidity gap. (orig.)
At present the cooler synchrotron COSY a synchrotron and storage ring for medium energy physics is being commissioned at Juelich. The construction of the ring was finished during September 1992. The cooler ring will deliver protons in the momentum range from 270 to 3300 MeV/c. The phase density of the circulating protons will be increased with electron cooling at injection and with stochastic cooling at momenta between 1500 and 3300 MeV/c. High luminosity internal experiments as well as high resolution external experiments will be possible. Details of the lattice, to match the different ion optical requirements for cooling, acceleration, internal experiments and ultra-slow extraction will be discussed. An overview of the performance of the ion sources, the injector cyclotron, the ring, the injection beamline are given. The realization status of the extraction beamlines to the external experimental area is given. The experience on the ...
The energy spectra of atmospheric-secondary protons and deuterium nuclei have been measured during the September 23, 1991, balloon flight of the NMSU/Wizard - MASS2 instrument. The apparatus was launched from Fort Sumner, New Mexico. The geomagnetic cutoff at the launch site is about 4.5 GV/c. The instrument was flown for 9.8 hours at an altitude of over 100,000 feet. Particles detected below the geomagnetic cutoff have been produced mainly by the interactions of the primary cosmic rays with the atmosphere. The measurement of cosmic ray energy spectra below the geomagnetic cutoff provide direct insights into the particle production mechanism and allows comparison to atmospheric cascade calculations.
We calculate the energy spectra of cosmic rays (CR) and their secondaries produced in a supernova remnant (SNR), taking into account the time-dependence of the SNR shock. We model the trajectories of charged particles as a random walk with a prescribed diffusion coefficient, accelerating the particles at each shock crossing. Secondary production by CRs colliding with gas is included as a Monte Carlo process. We find that SNRs produce less antimatter than suggested previously: The positron/electron ratio and the antiproton/proton ratio are a few percent and few $\\times 10^{-5}$, respectively. Moreover, the obtained positron/electron ratio decreases with energy, while the antiproton/proton ratio rises at most by a factor of two above 10 GeV.
A non-resonant RF cavity loaded with amorphous alloy cores has been designed and tested. The cavity has a re-entrant structure loaded with 8 amorphous alloy toroidal core and its characteristic impedance is designed as 450 Omega . The RF power is fed by 1 kW solid state amplifier using a step-up transformer with 1:9 impedance ratio. In the high power test, an accelerating gap voltage of more than 900 V was measured with input power of 1 kW in the frequency range of 1 to 10 MHz. The voltage standing wave ratio (VSWR) was less than 2.0. The results prove that the cavity may be used successfully within a compact proton synchrotron for a cancer therapy facility. (3 refs).
An appropriate mathematical model can help researchers to simulate, evaluate, and control a proton exchange membrane fuel cell (PEMFC) stack system. Because a PEMFC is a nonlinear and strongly coupled system, many assumptions and approximations are considered during modeling. Therefore, some differences are found between model results and the real performance of PEMFCs. To increase the precision of the models so that they can describe better the actual performance, optimization of PEMFC model parameters is essential. In this paper, an artificial bee swarm optimization algorithm, called ABSO, is proposed for optimizing the parameters of a steady-state PEMFC stack model suitable for electrical engineering applications. For studying the usefulness of the proposed algorithm, ABSO-based results...
The {rvec n} + p {yields} d + {gamma} experiment under construction at LANSCE studies the weak interaction between neutrons and protons. The experiments will measure the directional dependence of the parity-violating {gamma}-ray asymmetry, A{sub {gamma}}, in the polarized cold neutron capture by para-hydrogen. The goal is to measure A{sub {gamma}} with uncertainty of 0.5 x 10{sup -8}, 10% of its predicted value. A{sub {gamma}} primarily isolates the {Delta}I = 1 component of the hadronic weak interaction and thus will determine the long-range weak pion-nucleon coupling constant H{sub {pi}}{sup 1}. The experiment is carefully designed for the LANSCE pulsed spallation neutron source to achieve the proposed statistical precision and to control systematic errors. We discuss the experiment and its status.
In the CERN approach to the design of a neutrino factory, the repetition frequency of the proton beam is high enough to consider stationary solid targets as a viable solution for multi-MW beams. The target consists of high density tantalum spheres of 2 mm diameter which can efficiently be cooled by passing a high mass flow He-gas stream through the voids between the Ta-granules. Very small thermal shocks and stresses will arise in this fine grained structure due to the relatively long burst of 3.3 ms from the SPL-proton linac. In a quadruple target system where each target receives only one quarter of the total beam power of 4 MW, conservative temperature levels and adequate lifetimes of the target are estimated in its very high radiation environment. A conceptual design of the integration of the target into the magnetic horn-pion-collector is presented.
LECTURE SERIES 14, 15, 17 January 2008 11:00 to 12:00 - Council Chamber, bldg. 503-1-001 Applications of accelerators to tumour therapy U. AMALDI, TERA Foundation & University of Milano Bicocca The first lecture is devoted to an historical review of the developments of the teletherapy techniques which make use of hadron beams and are collectively called "hadrontherapy". The main emphasis is on the use of protons and light ions, but also neutrons, pions and antiprotons are considered. The second lecture reviews the rationale behind the use of carbon ions in the treatment of radioresistant tumours and the results obtained both with proton and carbon ion beams on the 60 000 patients treated worldwide. The numbers of patients who would profit from hadrontherapy are presented together with the current landscape of running and planned hospital based centres. The main technical challenges set by this therapeutic modality are discussed in the ...
Virtual Compton Scattering o013 the proton has been studied at Q 2 -values of 1:0 and 1:9 (GeV=c) 2 in Hall A at the Thomas Je013erson National Accelerator Facility (JLab). Data were taken below and above the pion production threshold as well as in the resonance region. Results obtained below pion threshold at Q 2 = 1:0 (GeV=c) 2 are presented in this paper.
ATP is synthesized by ATP synthase (FOF1-ATPase). Its rotary electromotor (FO) translocates protons (in some organisms sodium cations) and generates torque to drive...Full Text Available
Using the Relativistic Mean Field Theory (RMF) it is shown that different proton fraction which is directly connected with the neutron excess and with the asymmetry of the system affects proto-neutron stars parameters and changes their composition. The obtained form of the equation of state allows to construct the mass-radius relations and shows that the increasing asymmetry creates more compact stars. The inclusion of {delta} meson together with nonlinear vector meson interaction terms and magnetic field make this effect even stronger.
We discuss the description of the proton structure function within the dipole factorization framework. We parameterize the forward dipole amplitude to account for saturation as predicted by the small-x QCD evolution equations. Contrarily to previous models, the saturation scale does not decrease when taking heavy quarks into account. We show that the same dipole amplitude also allows to reproduce diffractive data and exclusive vector meson production.
Starting from the gauge hierarchy problem as a motivation, supersymmetric theories are reviewed. The minimal supersymmetric standard model is briefly described and the possible soft breaking terms of supersymmetry are introduced. Phenomenological questions are addressed for the flavor changing neutral current and CP violation. Phenomenological evidences for the supersymmetric grand unified models are reviewed and proton decay is examined. Relations with supergravity and superstring unification is also mentioned. (author).
Stable strange quark matter produced in the QCD phase transition in the early universe will trap neutrons and repel protons, thus reducing primordial helium production, Ysub(p). For reasonable values of Ysub(p), the radius of strange droplets must exceed 10/sup -6/ cm if strange matter shall solve the dark-matter problem without spoiling Big Bang helium synthesis. (orig.).
Stable strange quark matter produced in the QCD phase transition in the early universe will trap neutrons and repel protons, thus reducing primordial helium production, Ysub(p). For reasonable values of Ysub(p), the radius of strange droplets must exceed 10/sup 6/ cm if strange matter shall solve the dark-matter problem without spoiling Big Bang helium synthesis. (orig.).
The neutron deficient Sr and Zr nuclei are studied in the relativistic mean-field approach. Large deformations and shape coexistence are predicted for these nuclei in the vicinity of the proton drip line. The charge radii are found to increase with the removal of neutrons from the semimagic {sup 88}Sr and {sup 90}Zr, in close agreement with the recent isotopic-shift measurements.
A historical summary is made on the measurements concerning the rising total hadron-hadron cross sections at high energies. The first part of this paper concerns the total cross section measurements performed at the Brookhaven, Serpukhov and Fermilab fixed target accelerators; then the measurements at the CERN Intersecting Storage Rings (ISR), and at the CERN and at the Tevatron Fermilab proton-antiproton colliders; finally the cosmic ray measurements at even higher energies. A short discussion on Conclusions and Perspectives follows.
This document presents our proposal to continue the activities of Boston University researchers in eight projects in high energy physics research: Colliding Beams Physics; Accelerator Design Physics; MACRO Project; Proton Decay Project; Theoretical Particle Physics; Muon G-2 Project; and Hadron Collider Physics. The scope of each of these projects is presented in detail in this paper.
Modern particle accelerators offer new opportunities to dramatically reshape the way we think about nuclear energy, and challenge some of the thorniest problems linked to its industrial use, e.g. nuclear waste. A powerful proton accelerator driving a sub-critical fission reactor could be used for producing energy more safely and burning up the extra spent fuel which so far has been stored in geological repositories.
The inhibitor action of unbranched polyamines on corrosion of low-carbon steel in 0.5 M sulfuric acid is studied through potentiostatic polarization curves. It is shown that the inhibitor efficiency I depends on the polyamine concentration and molecular structure. The quantum-mechanical calculations of molecular properties are accomplished through the MNDO method. Correlation between the measured I and physicochemical properties of the polyamine inhibitors in protonized and nonprotonized form is found with application of the general perturbation theory
Plant roots release about 5% to 20% of all photosynthetically-fixed carbon, and as a result create a carbon-rich environment for numerous rhizosphere organisms, including plant pathogens and symbiotic...Full Text Available
Neutron Science Project was started at Japan Atomic Energy Research Institute since 1996 for promoting futuristic basic science and nuclear technology utilizing neutrons. For this purpose, research and developments of intense proton accelerator and spallation neutron target were initiated. The present paper describes the current status of such research and developments. (author)
Technical studies on constructing the J-PARC (Japan Proton Accelerator Research Complex) are presented by five authors: (1) on the wiring for electromagnets of the 50 GeV synchrotron, (2) on the fast beam-extraction from the 50 GeV synchrotron into two opposite directions, (3) on the target chamber system for the generation of muons, (4) on the design of large aperture electromagnets, and (5) on the maintenance and control of the electromagnet power supplies. (K.Y.)
The objectives of this R and D project are as follows : First, transferring developed technologies to outside companies and operating technology market to vitalize technology transactions, Second, developing commercial application projects to transfer technologies for commercial purposes and to solve interface problems in commercial applications, Third, enhancing commercial utilizations of developed accelerator and beam utilization technologies, Finally. preparing infra-structures for the development of over 30 venture- businesses based on achieved technologies through the Proton Engineering Frontier Project.
Plantago ovata Forsk - an economically important medicinal plant - was analyzed for trace elements and chlorophyll in a study of the effects of gamma radiation on physiological responses of the seedlings. Proton-induced X-ray emission (PIXE) technique was used to quantify trace elements in unirradiated and gamma-irradiated plants at the seedling stage. The experiments revealed radiation-induced changes in the trace element and chlorophyll concentrations.
The young open cluster Berkeley 87 was predicted to be associated with the COS B {gamma}-ray source 2CG 075+00 on the basis of the experimental evidence of the presence of a shock front around the Wolf - Rayet star ST3 placed in the inner part of the cluster. The CGRO phase-1 data confirm this identification. Protons accelerated at the shock boundary can produce {pi} deg. via p-p interactions and then {gamma}-rays. With the measured flux F{sub {gamma}} (E > 100 MeV) {approx_equal} 9x10{sup -7} ph cm{sup -2} s{sup -1} and the power-law proton spectrum with spectral index {gamma} = 2, the cosmic-ray-energy-density in the inner part ({approx} 0.8 pc radius) of Berk 87 is about 100 times greater than that in the vicinity of the Earth. We have calculated {gamma}-ray spectra expected from the decay of {pi}{sup d}eg. produced in p-p interactions. The spectra have been normalized to the observed flux of Berk 87 by using different input ...
Optical absorption measurements show that substitutional H"- ions, that is, protons with two electrons on anion sites, are thermally more stable than anion vacancies when thermochemically reduced CaO crystals are annealed in a reducing atmosphere. The H"- ions are identified by the infrared vibrational modes observed at 880 and 911 cm"-"1.
Recent nucleosynthesis calculations of Type II supernovae using advanced neutrino transport determine that the early neutrino winds are proton-rich. However, a fraction of the ejecta emitted at the same time is composed of neutron-rich pockets. In this paper we calculate the nucleosynthesis contribution from the neutron-rich pockets in the hot convective bubbles of a core-collapse supernova and show that they do not contribute significantly to the total nucleosynthesis.
The Monte Carlo simulation method is applied to calculate the nucleon transfer part of the imaginary optical-model potential in colliding heavy ions. In the process of transfer of nucleons from one nucleus to the other, forward and backward neutrons and protons are treated separately by taking into consideration the effect of the Coulomb forces and the potential energy surfaces (driving forces). The Pauli exclusion principle is also incorporated properly in the calculation.
The amino acid residues 114-118 in actin were found to be implicated strongly in the binding of nucleotide, and as would be expected for such an important binding site, they are located in a completely conserved region of the actin sequence. A 19-residue peptide with the actin sequence 106-124 was synthesized in order to span the putative triphosphate binding site. Proton NMR spectra of the actin peptide 114-118 in the presence and absence of ATP indicated that Arg-116 and Lys-118 are particularly involved in binding ATP. A strong binding of ATP to the peptide 106-124 also was measured. Tripolyphosphate bound to the peptide 106-124 somewhat more weakly than ATP. Binding involved residues 115-118 and 121-124, indicating the presence of a reverse turn between these segments. Proton resonances were assigned by using two-dimensional double quantum correlated spectroscopy, one-dimensional spin decoupling techniques, one-dimensional nuclear ...
To assess which specific morphologic features, enhancement patterns, or pharmacokinetic parameters on breast Magnetic Resonance Imaging (MRI) could predict a false-negative outcome of Proton...Full Text Available
An energy frontier or QCD Explorer ep and collider can be realized by colliding high-energy photons generated by Compton backscattered off a CLIC electron beam, at either 75 GeV or 1.5 TeV, with protons or ions stored in the LHC. In this study we discuss a performance optimization of this type of collider by tailoring the parameters of both CLIC and LHC. An estimate of the ultimately achievable luminosity is given.
Three resonances at the proton energies 7.0, 7.08, and 7.53 MeV on the target "8"8Sr were chosen to investigate the possibility of determining the amplitudes of the weak coupling experimentally. The corresponding "8"9Sr levels under investigation were 1.93 MeV ("5/_2"+), 2.00 MeV ("3/_2"+), and 2.46 MeV ("3/_2"+). Angular distributions were measured on resonance at 7.0, 7.08, and 7.53 MeV from proton inelastic scattering to the 1.84 MeV (2"+) state of "8"8Sr for differential cross section, analyzing power, spin-flip probability, and spin-flip asymmetry. A polarized beam of protons was used to obtain the analyzing power. The spin-flip probability was obtained from the coincidence of the prompt gamma rays from the (p,p'#gamma#) reaction with the scattered protons. With the polarized beam, the gamma coincidence technique was further used to obtain a spin-flip asymmetry measurement. From these measurements, ...
A discussion is presented of the 750-KeV chopper experience with both proton and negative ion beams and the ability of these systems to tailor the Linac beam to the diverse requirements of its users; normal accelerator injection, neutron therapy beam, and electron cooling experiments. This flexibility plus a cleaner beam pulse, improved thyratron operation, and mechanical modularity are the results of recent improvements. Additional benefits have been increased reliability and ease of service to the 750-KeV chopper. 3 refs.
The fragment separator at GSI, Darmstadt, has been used to produce and separate very proton rich nuclei in the {sup 100}Sn region. By fragmentation of a {sup 112}Sn beam at 1 A{center_dot}GeV we produced nuclei along the rp-process path between {sup 77}Y and {sup 98}In. By implanting these ions into a silicon detector stack we were able to determine their halflives. Preliminary data are presented.
Effect of proton backscattering on inelastic pd-scattering is discussed in detail. The discussion was carried out on the basis of interaction mechanism if bombarding particle with flucton. It is noted that fluctons are assumed presently as time multiquark formations of nuclear matter with the size of nucleon size order and density above nucleon one. 35 refs., 10 figs.
Modern nuclear spectroscopy boosts the study of the nuclear matter towards extreme conditions: large excitation energies, high spins, and new nuclear species with unusual ratio between the numbers of neutrons and protons. One of the 'exotic' nuclear regions, practically not studied until now, is the upper part of the N=Z line, from about N#approx#Z#approx#36 to Sn-100, probably the heaviest bound nucleus with N=Z. These nuclei lie close to the proton-drip line. Due to their special composition, it is expected that their study will reveal some phenomena which are less encountered in the nuclei studied till now. In particular, of outstanding interest is the fact that these are the only nuclei which may provide information on the properties of the neutron-proton pairing forces. In spite of its large interest, this nuclear region is exceedingly difficult to reach with the present techniques. The lecture follows the latest ...
The protonation constants (KiH) of 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-3,6,9,-triacetic acid (PCTA) and stability constants of...Full Text Available
It has been shown for the first time that astatine is capable of undergoing addition reactions to unsaturated hydrocarbons. A new compound of astatine, viz., ethylene astatohydrin, has been obtained, and its retention numbers of squalane, Apiezon, and tricresyl phosphate have been found. The influence of various factors on the formation of ethylene astatohydrin has been studied. It has been concluded on the basis of the results obtained that the univalent cations of astatine in an acidic medium is protonated hypoastatous acid.
The excitation of compound-nucleus resonances in Y/sup 89/ and Zr/sup 90/ by proton bombardment at 4 to 5.5 Mev of Sr/sup 88/ and Y/sup 89/, respectively, is reported. Shell-model corfigurations were used to interpret the results. (R.E.U.)
A microwave hydrogen ion source was developed to improve reliability, and to increase operation time of proton linac application systems. The ion source needs no filament in the discharge chamber, which leads to better reliability and less maintenance time. The developed source produced a maximum hydrogen ion beam current of 70 mA (high current density of 360 mA/cm2, beam energy of 30 keV) with a 5 mm diam extraction aperture and 1.2 kW microwave power. The proton fraction was increased with an increase in rf power and reached around 90% at 1 kW. Measured 90% beam normalized emittance was 0.4 #pi# mm mrad. Rise times of rf power and beam current to 90% of the final values were about 30 and 35 #mu#s, respectively, at a pulse operation mode with 400 #mu#s pulse width and 100 Hz repetition rate. The dynamic range of beam currents was enlarged (3-63 mA) in the pulse mode with a modified rf wave form to assist ignition of microwave discharge. These ...
The relative merits and difficulties of the primary and secondary origin hypotheses for the observed cosmic ray antiprotons, including the low energy measurement of Buffington, were examined. It is concluded that the cosmic ray antiproton data may be strong evidence for antimatter galaxies and baryon symmetric cosmology. The present antiproton data are consistent with a primary extragalactic component having antiproton/proton approximately equal to .0032 + or - 0.7.
Chemical effects on the intensity ratio of LX-ray of molybdenum compounds irradiated by 11-keV electrons and by 3-MeV protons were studied using an x-ray crystal spectrometer. It was found that the intensity ratios of L_#gamma#_1/L_#beta#_1 markedly decrease with the increase of ionicity of molybdenum compounds, except for the case of metallic molybdenum. (author).
Active galactic nuclei (AGNs) and quasars (QSOs) appear to emit roughly equal energy per decade from radio to gamma-ray energies (e.g. Ramaty and Ligenfelter 1982). This argues strongly for a nonthermal radiation mechanism (see Rees 1984). In addition, statistical studies have indicated that the spectra of these objects in the IR-UV and 2 to 50 keV x-ray band, can be fitted very well with power laws of specific indices. These spectral indices do not seem to depend on the luminosity or morphology of the objects (Rothschild et al. 1983; Malkan 1984), and any theory should account for them in a basic and model independent way. If shocks accelerate relativistic protons via the first-order Fermi mechanism (e.g. Axfor 1981), the radiating electrons can be produced as secondaries throughout the source by proton-proton (p-p) collisions and pion decay, thus eliminating Compton losses (Protheroe and Kazanas 1983). As shown by Kazanas (1984), if ...
The ..beta.. decay half-lives of neutron-rich isotopes with Z=24-28 are calculated in the QRPA with a Gamow-Teller residual interaction. For odd-mass and odd-odd systems QRPA phonon correlations are introduced to quasiparticle transitions in first-order perturbation. The calculated half-lives agree very well with the experimental values. For later application of this model to nuclei far from stability, we have examined the dependence of the calculated half-lives on the model parameters.
The #beta# decay half-lives of neutron-rich isotopes with Z=24-28 are calculated in the QRPA with a Gamow-Teller residual interaction. For odd-mass and odd-odd systems QRPA phonon correlations are introduced to quasiparticle transitions in first-order perturbation. The calculated half-lives agree very well with the experimental values. For later application of this model to nuclei far from stability, we have examined the dependence of the calculated half-lives on the model parameters. (orig.).
The resonance reaction /sup 11/B(p,/alpha/)/sup 8/Be was used to determine the boron profiles in the surface of: (1) boron implanted silicon; (2) boron diffused silicon; and (3) boron containing films deposited on silicon wafers. The boron distribution in the various samples was found to be stable under the bombardment of the proton beam. The convolution process used to obtain yield curves from the depth distribution, and the program used for this purpose are described.
We consider electromagnetic corrections at finite temperature and their effect on the nucleosynthesis in the standard Big Bang scenario. This requires discussing the finite, temperature dependent correction to the neutron-proton mass difference as well as making use of a previous result on the temperature correction to the mass of the electron. We find that these corrections do not affect the conventional results of e.g. the helium abundance to any appreciable extent.
The beam-beam interaction in the Tevatron produce the betatron tune spread in each bunch and a bunch-to-bunch tune spread. The tune spread sets limits on bunch intensity and luminosity. The beam-beam effects for antiprotons are usually more severe since the proton bunch population is higher. The beam-beam effects for antiprotons can in principle be compensated with the use of an electron beam with a corresponding charge density. The status of studies of possibilities of the beam-beam compensation is reviewed in this paper.
This report seeks to address the role of hydrogen bonding with Bronsted acids and bases in proton-coupled electron transfer (PCET) as it pertains to concerted or stepwise pathways of quinone (Q) and hydroquinone (QH_2) electrochemistry. This study was performed using a series of techniques that included cyclic voltammetry (CV), digital simulations, computational chemistry and "1H NMR. Hydrogen bonding was inferred by a decrease in diffusion coefficient (D) values measured using a pulsed gradient echo- (PGE-) "1H NMR technique. Changes of 40.8% and 37.9% in D values were only noted after the addition of two equivalents of acetate to 1,4-hydroquinone (1,4-QH_2) and catechol (1,2-QH_2), respectively. In contrast, the D values for the addition of selected amines (pyridine, N,N-diisopropylethylamine and triethylamine) changed only 3.2% on average. Quantum mechanical calculations were conducted to determine the pK_a of all quinoid species to serve as a starting point for ...
Helical dipole magnets are required in a project for the Relativistic Heavy Ion Collider (RHIC) to control and preserve the beam polarization in order to allow the collision of polarized proton beams. Specifications are for low current superconducting magnets with a 100 mm coil aperture and a 4 Tesla field in which the field rotates 360 degrees over a distance of 2.4 meters. A magnet meeting the requirements has been developed that uses a small diameter cable wound into helical grooves machined into a thick-walled aluminum cylinder.
The proton beam has an advantage of the sharp dose falloff in dose distribution called Bragg peak while conventional radiation therapy modalities such as photons exhibit considerable amount of exit dose. To take advantage of this property it is important to know the exact location of the distal dose falloff. An error can cause overdose to the normal tissue or underdose to the tumor volume. The only way of finding out the dose distribution in-situ in particle therapy is to measure the gammas produced by nuclear reactions with tissue materials. Two kinds of gammas can be used: one is prompt gamma and the other is coincident gamma from the positron-emission isotopes. We chose to detect prompt gammas, and developed a prompt gamma scanning system (PGS). The proton beams of the proton therapy facility at National Cancer Center were used. The gamma distribution was compared to the dose distribution measured by an ionization ...
A proton exchange membrane fuel cell (PEMFC) must maintain a balance between the hydration level required for efficient proton transfer and excess liquid water that can impede the flow of gases to the electrodes where the reactions take place. Therefore, it is critically important to understand the two-phase flow of liquid water combined with either the hydrogen (anode) or air (cathode) streams. In this paper, we describe the design of an in situ test apparatus that enables investigation of two-phase channel flow within PEMFCs, including the flow of water from the porous gas diffusion layer (GDL) into the channel gas flows; the flow of water within the bipolar plate channels themselves; and the dynamics of flow through multiple channels connected to common manifolds which maintain a uniform pressure differential across all possible flow paths. These two-phase flow effects have been studied at relatively low operating temperatures under ...
The covariant quark model is shown to allow a phenomenological description of the neutron electric form factor, G{sub E}{sup n}(Q{sup 2}), in the impulse approximation, provided that the wave function contains minor ({approx}3%) admixtures of the lowest energy sea-quark configurations. While that form factor is not very sensitive to whether the q{sup -} in the qqqqq{sup -} component is in the P-state or in the S-state, the calculated nucleon magnetic form factors are much closer to the empirical values in the case of the former configuration. In the case of the electric form factor of the proton, G{sub E}{sup p}(Q{sup 2}) a zero appears in the impulse approximation close to 10 GeV{sup 2}, when the q{sup -} is in the P-state. That configuration, which may be interpreted as a pion loop ('cloud') fluctuation, also leads to a clearly better description of the nucleon magnetic moments. When the amplitude of the sea-quark admixtures are set so as to ...
The removal of heavy metal by microbial biomass have been investigated as an alternative to the traditional methods. The removal of the heavy metals copper and iron from discarded lubricating-oil was studied using the biosorbent Sargassum sp. It was chosen a discarded lubricating-oil of a bus fleet from the city of Natal-RN-Brazil. The oil was characterized to determine and quantify the heavy metals present. The effect of biomass protonation was performed in order to increase the removal efficiency of the metals. The equilibrium time between the oil and the biomass was determined. It was found that after 10 hours the equilibrium was reached. It was also studied the influence of biomass quantity. The results showed that the biomass quantity is an important parameter to the efficiency and biosorption capacity. The protonated biomass was shown more efficient to removal of Fe and Cu, removing 37,53% and 31,63% respectively. (author)
The performance of a 6 kW proton exchange membrane (PEM) electrolyzer was modeled using a semiempirical equation. Total cell voltage was represented as a sum of the Nernst voltage, activation overpotential and ohmic overpotential. A temperature and pressure dependent Nernst potential, derived from thermodynamic principles, was used to model the 20 cell PEM electrolyzer stack. The importance of including the temperature dependence of various model components is clearly demonstrated. The reversible potential without the pressure effect decreases with increasing temperature in a linear fashion. The exchange current densities at both the electrodes and the membrane conductivity were the coefficients of the semiempirical equation. An experimental system designed around a 6 kW PEM electrolyzer was used to obtain the current-voltage characteristics at different stack temperatures. A nonlinear curve fitting method was employed to determine the equation coefficients from ...
The world fusion program has advanced to the stage where it is appropriate to construct a number of devices for the purpose of burning DT fuel. In these next-generation experiments, the expected flux and fluence of 14 MeV neutrons and associated gamma rays will pose a significant challenge to the operation and diagnostics of the fusion device. Radiation effects include structural damage to materials such as vacuum windows and seals, modifications to electrical properties such as electrical conductivity and dielectric strength and impaired optical properties such as reduced transparency and luminescence of windows and fiber optics during irradiation. In preparation for construction and operation of these new facilities, the fusion diagnostics community needs to work with materials scientists to develop a better understanding of radiation effects, and to undertake a testing program aimed at developing workable solutions for this multi-faceted problem. A unique facility to help in this ...
Thin PTFE membranes were prepared by coating the PTFE dispersion onto the aluminum films. Thus the thin crosslinked PTFE (RX-PTFE) membranes were obtained by means of electron beam irradiation above the melting temperature of PTFE under oxygen-free atmosphere. The RX-PTFE membranes were pre-irradiated and grafted by styrene with or without divinylbenzene (DVB) in liquid phase. The existence of DVB accelerated the initial grafting rate. The styrene grafted RX-PTFE membranes are white colored, on the other hand, the styrene/DVB grafted RX-PTFE membranes are colorless. The proton exchange membranes (PEMs) were obtained by sulfonating the grafted membranes using chlorosulfonic acid. The ion exchange capacity (IEC) values of the PEMs ranging from 1.5 to 2.8 meq/g were obtained. The PEMs made from the styrene/DVB grafted membranes showed higher chemical stability than those of the styrene grafted membranes under oxidative circumstance.
H Power Enterprises of Canada was founded in 1997; currently, it has 40 employees and expect to grow to about 50 by mid-2000. The company is engaged in fuel cell technology development , manufacturing and marketing. The company has the advantage that its technology has been proven, products are already commercialized, and strategic alliances are already in place to make an assault on the market. The concept of proton exchange membrane fuel cell technology is explained in terms of efficiency, response time, power density, stack manufacturing cost, maintenance cost, stack life and compatible thermal loads. Individual products, their energy and operating efficiency, potential applications and potential markets are reviewed. It is estimated that for stationary fuel cells the market will be worth $ 30 billion by 2030. In the United States alone, remote residential cogeneration sites are estimated at 500,000. The estimates for uses in transportation is estimated at $ 1 ...
The authors propose to develop a high-energy heavy-ion experimental database and make it accessible to the scientific community through an on-line interface. This database will be searchable and cross-indexed with relevant publications, including published detector descriptions. Since this database will be a community resource, it requires the high-energy nuclear physics community's financial and manpower support. This database should eventually contain all published data from Bevalac, AGS and SPS to RHIC and CERN-LHC energies, proton-proton to nucleus-nucleus collisions as well as other relevant systems, and all measured observables. Such a database would have tremendous scientific payoff as it makes systematic studies easier and allows simpler benchmarking of theoretical models to a broad range of old and new experiments. Furthermore, there is a growing need for compilations of high-energy nuclear data for applications including stockpile stewardship, ...
Thermal (gas) nitridation of stainless steel alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant nitride containing surface layers (Cr2N, CrN, TiN, V2N, VN, etc.) of interest for fuel cells, batteries, and sensors. This paper presents results of scale-up studies to determine the feasibility of extending the nitridation approach to thin 0.1mm stainless steel alloy foils for proton exchange membrane fuel cell (PEMFC) bipolar plates. Developmental Fe-20Cr-4V alloy and type 2205 stainless steel foils were treated by pre-oxidation and nitridation to form low-ICR, corrosion-resistant surfaces. As-treated Fe-20Cr-4V foil exhibited target (low) ICR values, whereas 2205 foil suffered from run-to-run variation in ICR values, ranging up to 2x the...
Thermal (gas) nitridation of stainless steel alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant nitride containing surface layers (Cr2N, CrN, TiN, V2N, VN, etc.) of interest for fuel cells, batteries, and sensors. This paper presents results of proton exchange membrane (PEM) single-cell fuel cell studies of stamped and pre-oxidized/nitrided developmental Fe-20Cr-4V weight percent (wt.%) and commercial type 2205 stainless steel alloy foils. The single-cell fuel cell behavior of the stamped and pre-oxidized/nitrided material was compared to as-stamped (no surface treatment) 904L, 2205, and Fe-20Cr-4V stainless steel alloy foils and machined graphite of similar flow field design. The best fuel cell behavior among the alloys was exhibited...
This work deals with a new route to modify polymer blend morphology in order to improve the porosity of gas diffusion layers (GDLs) for proton exchange membrane fuel cells (PEMFCs). First, electrically conductive polymer-based blends were carefully formulated using a twin-screw extrusion process. Blend electrical conductivity was ensured by the addition of high specific surface area carbon black and synthetic graphite flakes. Final GDL porosity, in particular its macroporosity, was generated by melt blending polyamide 11 (PA11) matrix with polystyrene (PS) followed by PS extraction with tetrahydrofuran (THF) solvent at room temperature. In order to improve GDL porosity by the optimisation of PS dispersion in the PA11 matrix, PA11/PS blends were compatibilised by the addition of 2 wt.-% of clay. It was observed that both macroporosity and pore size distribution were beneficially modified after blend compatibilisation. Final GDL conductivity of about 1.25 S cm{sup ...
AMS is a particle detector designed to perform high precision measurements of the cosmic rays fluxes with the main goals of searching for anti-nuclei, as remnants of primordial anti-matter, and of measuring the faintest components of the cosmic flux, anti- protons, positrons and high energy photons. To fulfill the requirements of large acceptance, long exposure time and excellent particle identification needed to achieve the intended results, AMS will operate in space as an attached payload to the International Space Station (ISS), being the first full featured particle physics experiment to operate in the Earth orbit. The AMS-02 accurate measurements of cosmic-ray nuclei, protons, antiprotons, electrons and positrons will be completed by high energy gamma rays detection. The experiment will detect gamma-rays, either by reconstructing e+e? pairs generated by photons converted upstream the tracker (conversion mode), or based on direct ...
Recently PAMELA released their first results on the positron and antiproton ratios. Stimulated by the new data, we studied the cosmic ray propagation models and calculated the secondary positron and antiproton spectra. The low energy positron ratio can be consistent with data in the convection propagation model. Above $\\sim 10$ GeV PAMELA data shows a clear excess on the positron ratio. However, the secondary antiproton is roughly consistent with data. The positron excess may be a direct evidence of dark matter annihilation or decay. We compare the positron and anti-proton spectra with data by assuming dark matter annihilates or decays into different final states. The PAMELA data actually excludes quark pairs being the main final states, disfavors gauge boson final states. Only in the case of leptonic final states the positron and anti-proton spectra can be explained simultaneously. We also compare the decaying and annihilating dark matter ...
Using the advantage that the projected range of ions in matter is sharply limited, a new technique for the production of three-dimensional microstructures has been developed. Based on the P-LIGA technique (Proton-Lithographie, Galvanoformung, Abformung) this process allows the generation of structures with surfaces of almost any shape having a root mean square roughness of about #lambda#/50 for visible light wavelengths. An ion beam with diameters between 2 and 50 #mu#m is directly writing the structures and the shape is varied by geometrical manipulation of the sample in three axes during the exposure. Practically, structures have been written using protons with an energy of 1.8 MeV in a provisional experimental setup with beam diameters of 10 and 50 #mu#m, respectively. After irradiation, the parts exposed were dissolved in a liquid developer without affecting the nonirradiated parts. The shape and the rms roughness of the resulting ...
Examination of a chloroform extract of Dracaena loureiri Gagnep (Agavaceae), a Thia medicinal plant possessing antibacterial activity, has led to the isolation of fifteen flavenoids. The biogenic relationships among these flavenoids isolated were briefly discussed. Definition of the skeleton and the unambiguous assignment of all of the protons of the isolates was achieved through extensive 2D-homonuclear chemical shift correlation, nuclear Overhauser effect (NOE) difference spectroscopy and 2D-NOE experiments. The {sup 1}H and {sup 13}C NMR spectra of staurosporine, a potent biologically active agent from Streptomyces staurosporeus, were unambiguously assigned by using 2D homonuclear chemical shift correlation, NOE, {sup 1}H-detected heteronuclear multiple-quantum coherence via direct coupling and via multiple-bond coupling for resonance assignments of protonated and nonprotonated carbons, respectively. S. Staurosporeus was found to utilize ...
Evaluation of nuclear data has been performed for {sup 237}Np, {sup 241}Am, {sup 242g}Am and {sup 242m}Am. Neutron data were obtained at energies from 20 to 250 MeV and combined with JENDL-3.3 data at 20 MeV. Evaluation of the proton data has been done from 1 to 250 MeV. The coupled channel optical model was used to obtain angular distributions for elastic and inelastic scattering and transmission coefficients. Pre-equilibrium exciton model and Hauser-Feshbach statistical model were used to describe neutron and charged particles emission from excited nuclei. These evaluation is the first work for producing full sets of evaluated file up to 250 MeV for {sup 237}Np and Americium isotopes. (author)
Evaluation of nuclear data has been performed for sup 2 sup 3 sup 7 Np, sup 2 sup 4 sup 1 Am, sup 2 sup 4 sup 2 sup g Am and sup 2 sup 4 sup 2 sup m Am. Neutron data were obtained at energies from 20 to 250 MeV and combined with JENDL-3.3 data at 20 MeV. Evaluation of the proton data has been done from 1 to 250 MeV. The coupled channel optical model was used to obtain angular distributions for elastic and inelastic scattering and transmission coefficients. Pre-equilibrium exciton model and Hauser-Feshbach statistical model were used to describe neutron and charged particles emission from excited nuclei. These evaluation is the first work for producing full sets of evaluated file up to 250 MeV for sup 2 sup 3 sup 7 Np and Americium isotopes.
This paper reports on the superiority of zeolites over amorphous solids which is well documented for solid acid catalysts of industrial use. Crystalline supports, likewise, open attractive perspectives for catalysis by metals, alloys, and ligated metal clusters. Size and location of clusters can be controlled by careful design of the preparation conditions. Pore dimensions control the access of reactants to active sites and escape paths for products. Cage dimensions determine which transition states can be attained; window apertures are functional in isolating metal clusters from each other, thus preventing ther coalescence and growth. The ship-in-a-bottle method permits deisgn of fairly large active complexes entrapped in zeolite cages. Orientation of non-spherical molecules in a zeolite proe helps to direct their collision with a metal particle to the head on mode; however, isolated Pt atoms hidden in niches of the pore walls can attack passing molecules at their soft flanks. ...
Proton exchange membrane fuel cells (PEMFCs) are attractive because of their high conversion efficiency, low pollution, lightweight, and high power density. A major area of challenges is the design and engineering of active, robust, and low-cost electrocatalysts. This report discusses recent findings of our investigations of the design and nano-engineering of platinum-vanadium-iron catalysts for use in PEMFC. The membrane electrode assembly was prepared using nano-engineered PtVFe nanoparticles with controlled composition and size supported on carbon as cathode electrocatalysts. The electrocatalytic activity and stability of the catalysts have been characterized by both rotating disk electrode and membrane electrode assembly measurements. The trimetallic catalysts have been shown to exhibit excellent electrocatalytic performance in PEMFC in comparison with commercial platinum catalysts. The results exhibited a good agreement between obtained these two types of ...
Angelin Pedra is a specie found in the north of Mato Grosso State in Brazil, where an expressive volume of waste of this wood is produced. An alternative to recycle this waste is to produce wood plastic composites. However, structural and chemical investigations are fundamental to generate information for this use. In the present work, low field NMR was used to determine the spin-lattice and spin-spin relaxation times with objective to investigate the molecular dynamic behavior of the alburnu and cerne regions of Angelin Pedra aiming at a potential use of this waste wood in polymeric composites. The results of the proton spin-lattice relaxation time (T1H) and the proton spin-spin relaxation time (T2H) showed at least three different mobility domains for both regions. Among the values, one was very flexible and other was rigid. Knowing that wood is a polymer composite basically constituted by cellulose, hemicellulose and lignin can attribute the ...
Minority-carrier lifetime damage coefficients for 1 MeV electron, 3 MeV proton, and 6 MeV alpha particle irradiation of n-type (4.5{times}10{sup 15} and 1.3{times}10{sup 17}cm{sup {minus}3}) and p-type (2.5{times}10{sup 17}cm{sup {minus}3}) InP have been measured using time-resolved photoluminescence. These values are relatively insensitive to carrier type and show a slight increase with increasing carrier concentration. Evidence of comparable electron and hole capture lifetimes is found for the dominant recombination defect. The effect of 3 MeV proton and 6 MeV alpha particles relative to 1 MeV electrons is an increase in the lifetime damage coefficient by factors of about 10{sup 4} and 10{sup 5}, respectively. {copyright} {ital 1997 American Institute of Physics.}
Semi-inclusive pi+ electroproduction on protons has been measured with the CLAS detector at Jefferson Lab. The measurement was performed on a liquid-hydrogen target using a 5.75 GeV electron beam. The complete five-fold differential cross sections were measured over a wide kinematic range in Q2, x, z, and pT and over the complete range of azimuthal angles, phi, enabling us to separate the different structure functions, H2+eps*H1, H3 and H4. Our measurements of H2 at low-x were found to be in fairly good agreement with pQCD calculations, suggesting a precocious factorization of the process. Indeed, the conventional f(x)*D(z) term can account for almost all of the observed cross section, even at small z. The measured xF-distributions are in qualitative agreement with high energy data, which suggests a surprising numerical similarity between the spectator diquark fragmentation in the present reaction and the anti-quark fragmentation measured in e+e- collisions. We ...
The National Spallation Neutron Source (NSNS), in which neutrons are generated by bombarding a liquid mercury target with 1 GeV protons, will place extraordinary demands on materials performance. The target structural material will operate in an aggressive environment, subject to intense fluxes of high energy protons, neutrons, and other particles, while exposed to liquid mercury and to water. Components that require special consideration include the Hg liquid target container and protective shroud, beam windows, support structures, moderator containers, and beam tubes. In response to these demands a materials R and D program has been developed for the NSNS that includes: selection of materials; calculations of radiation damage; irradiations, post irradiation testing, and characterization; compatibility testing and characterization; design and implementation of a plan for monitoring of materials performance in service; and materials engineering ...
The masses of the proton-rich nuclides {sup 85,86,87}Mo and {sup 87}Tc have been measured with the Penning trap mass spectrometer SHIPTRAP at GSI. The measured mass excesses of these nuclei deviate from the values of the Atomic Mass Evaluation 2003 by up to 1.6 MeV, indicating a systematic shift of the mass surface in this region compared to previous measurements. A local mass extrapolation based on the new results has been made for the mass range A=80-95. Measured and extrapolated mass values and the derived separation energies have been compared to theoretical mass models. Taking into account the new mass excess values, rp-process network calculations have been performed. Preliminary results show changes in the final abundances for A=86-92 by up to a factor of 30. Results of measurements and calculations are presented, and the issue of a potential Zr-Nb cycle is addressed.
The masses of the proton-rich nuclides "8"5","8"6","8"7Mo and "8"7Tc have been measured with the Penning trap mass spectrometer SHIPTRAP at GSI. The measured mass excesses of these nuclei deviate from the values of the Atomic Mass Evaluation 2003 by up to 1.6 MeV, indicating a systematic shift of the mass surface in this region compared to previous measurements. A local mass extrapolation based on the new results has been made for the mass range A=80-95. Measured and extrapolated mass values and the derived separation energies have been compared to theoretical mass models. Taking into account the new mass excess values, rp-process network calculations have been performed. Preliminary results show changes in the final abundances for A=86-92 by up to a factor of 30. Results of measurements and calculations are presented, and the issue of a potential Zr-Nb cycle is addressed.
We studied the magnetic dipole moments #mu# of even-odd C isotopes, ranging from proton-rich to neutron-rich nuclei, with antisymmetrized molecular dynamics (AMD). The results are in good agreement with the experimental data. In the "9C ground state the total intrinsic spin of the protons is found to be nonzero (S_p#not =#0), which is unusual in even-odd nuclei. The interesting point is that the spin-orbit force breaks slightly the coupling off of intrinsic spins of the even nucleon group in isospin T=3/2 nuclei. This result is consistent with the newly measured #mu# data that, when combined with "9Li data, indicate an unusual left-angle #sigma# right-angle value larger than unity. A #mu# moment -1.05#mu#_N of "1"7C is theoretically predicted. We also show a good reproduction of E2 transition data. copyright 1996 The American Physical Society.
Thick targets of several heavy lanthanide (Ho-Lu) compounds were bombarded by protons and /sup 3/He ions of 3 MeV/amu, and M/sub ..cap alpha../ and M/sub ..beta../ X-rays were measured with a crystal spectrometer. Ionization probabilities of the N-shell for zero impact parameter were obtained from the X-ray intensity ratio for proton and /sup 3/He ion impacts. A shell dependence of the ionization probability was found in a scaling plot. X-ray spectra of lanthanide compounds were compared and no chemical effect was observed. This result is considered to be due to the fact that the main component of M/sub ..cap alpha../ and M/sub ..beta../ lines is for radiative transition after the refilling of the 4f orbit (3d/sup -1/4f/sup n+1/ -> 4f/sup n/) where n denotes the number of 4f electrons of the target atom before ionization.
Theoretical interpretation of fast-charged-particle spectra, observed in the #alpha#-particle-induced reactions on the s-d shell nuclei (A = 24-28), in terms of the Intranuclear Cascade Model and the GDH exciton model (ALICE) is presented. The de-excitation of the excited residual nuclei is accounted for by the evaporation process. The theoretically predicted fast-proton and #alpha#' spectral shapes compare reasonably well with the corresponding measured spectra. However, the magnitude depends critically (as expected) on the reaction cross section employed by the model. As a first step to improve the model predictability of the reaction products, a closer look at the calculation of the #alpha#-particle reaction cross sections was undertaken. A microscopic approach using the optical theorem of Glauber's theory was employed to estimate the #alpha#-induced reaction cross sections for the light target nuclei under consideration. The calculated particle spectra were ...
We discuss the impact for light neutralinos in an effective Minimal Supersymmetric extension of the Standard Model of the recent results presented by the CMS and ATLAS Collaborations at the CERN Large Hadron Collider for a search of supersymmetry in proton-proton collisions at a center-of-mass energy of 7 TeV with an integrated luminosity of 35 inverse pb. We find that, in the specific case of light neutralinos, efficiencies for the specific signature searched by ATLAS (jets+missing transverse energy and an isolated lepton) imply a lower sensitivity compared to CMS (which searches for jets +missing transverse energy). Focusing on the CMS bound, if squark soft masses of the three families are assumed to be degenerate, the combination of the ensuing constraint on squark and gluino masses with the experimental limit on the b to s + gamma decay imply a lower bound on the neutralino mass that can reach the value of 11.9 GeV, depending on the gluino mass. On the other ...
In the presence of hydroxyl anion, both formaldehyde and glyoxal are known to undergo rearrangements involving intermolecular and intramolecular hydride transfer (the Cannizzaro and Benzilic acid rearrangements respectively). The authors report ab initio SCF-MO calculations of the transition state geometries, the activation barriers, and the hydrogen isotope effects for these two reactions. The structure of the transition state for the rection involving formaldehyde is usually basis set dependent, becoming more linear and symmetrical as the basis set size increases. In contrast, the analogous transition state for the glyoxal reaction involves a highly non-linear hydride transfer. They find the isotope effects to be quite low for the Cannizzaro reaction, and significantly larger for the non-linear benzilic acid rection, in apparent contradiction to Westheimer's suggestion the isotope effects reach a maximum for linear hydrogen transfers. Since this hypothesis does seem to be true for ...
The new proton-induced nuclear reaction data for C, Fe, Cu and Pb for KASKAD-S have been generated using a newly developed data preparation system. The new system utilizes the NJOY and TRANSX codes to prepare these data with the latest evaluation instead of using the SADCO code with the built-in nuclear data. Auxiliary codes have been developed to help the conversion of TRANSX output into the reaction data for running the KASKAD-S. The basic nuclear data selected for this work are the LA150 and KAERI high energy files whose energy ranges are up to 150 and 250 MeV, respectively. The total neutron yields were calculated using KASKAD-S and the new reaction data up to 250 MeV bombarding energy. The calculations were compared with the measurements or MCNPX calculations when the measured data were absent. The comparison shows that our calculations give an overall good agreement with the measurements and MCNPX calculations except around 30 MeV where large discrepancies ...
Aims: The production of saturated organic molecules in hot cores and corinos is not well understood. The standard approach is to assume that, as temperatures heat up during star formation, methanol and other species evaporate from grain surfaces and undergo a warm gas-phase chemistry at 100 K or greater to produce species such as methyl formate, dimethyl ether, and others. But a series of laboratory results shows that protonated ions, typical precursors to final products in ion-molecule schemes, tend to fragment upon dissociative recombination with electrons rather than just ejecting a hydrogen atom. Moreover, the specific proposed reaction to produce protonated methyl formate is now known not to occur at all. Methods: We utilize a gas-grain chemical network to probe the chemistry of the relatively ignored stage of hot core evolution during which the protostar switches on and the temperature of the surrounding gas and dust rises from 10 K to ...
We compare the physics potential of the upcoming neutrino oscillation experiments Daya Bay, Double Chooz, NOvA, RENO, and T2K based on their anticipated nominal luminosities and schedules. After discussing the sensitivity to theta_{13} and the leading atmospheric parameters, we demonstrate that leptonic CP violation will hardly be measurable without upgrades of the T2K and NOvA proton drivers, even if theta_{13} is large. In the presence of the proton drivers, the fast track to hints for CP violation requires communication between the T2K and NOvA collaborations in terms of a mutual synchronization of their neutrino-antineutrino run plans. Even in that case, upgrades will only discover CP violation in a relatively small part of the parameter space at the 3 sigma confidence level, while 90% confidence level hints will most likely be obtained. Therefore, we conclude that a new facility will be required if the goal is to obtain a significant ...
The masses of proton rich nuclides in the vicinity of N=Z=43 were measured with the Penning trap mass spectrometer SHIPTRAP at GSI. These nuclei were produced in the fusion-evaporation reaction {sup 36}Ar+{sup 54}Fe at energies of 5.0 and 5.9 MeV/u and separated at the velocity filter SHIP. The data are of astrophysical interest since these nuclei are believed to be a part of the rp and {nu}p process paths. The masses of {sup 85}Mo and {sup 87}Tc were measured for the first time. The masses of another two nuclides, {sup 86,87}Mo, were determined for the first time in a direct mass measurement. For these nuclides the mass excess deviates from values of the 2003 Atomic Mass Evaluation by up to 1.5 MeV, indicating a systematic shift of the mass surface in this region of the nuclear chart. Additionally, the masses of {sup 86}Zr and {sup 85}Nb were measured and found to be in agreement with the values obtained at JYFLTRAP. The experiment as well as preliminary data on ...
The masses of proton rich nuclides in the vicinity of N=Z=43 were measured with the Penning trap mass spectrometer SHIPTRAP at GSI. These nuclei were produced in the fusion-evaporation reaction "3"6Ar+"5"4Fe at energies of 5.0 and 5.9 MeV/u and separated at the velocity filter SHIP. The data are of astrophysical interest since these nuclei are believed to be a part of the rp and #nu#p process paths. The masses of "8"5Mo and "8"7Tc were measured for the first time. The masses of another two nuclides, "8"6","8"7Mo, were determined for the first time in a direct mass measurement. For these nuclides the mass excess deviates from values of the 2003 Atomic Mass Evaluation by up to 1.5 MeV, indicating a systematic shift of the mass surface in this region of the nuclear chart. Additionally, the masses of "8"6Zr and "8"5Nb were measured and found to be in agreement with the values obtained at JYFLTRAP. The experiment as well as preliminary data on mass values, separation ...
There is an increasing interest in using radioisotopes of rare earth elements for internal radiotherapy and for imaging in nuclear medicine. {sup 177}Lu is one of the promising radionuclides. This article reports on the first measurements of the excitation function for the production of {sup 177}Lu with proton-beam energies up to 17 MeV on natural hafnium targets. The experimental cross sections for the reaction {sup nat}Hf(p,x){sup 177}Lu were obtained by the activation of a stacked-foil target and subsequent gamma spectrometry. Theoretical cross sections were calculated up to 35 MeV with the EMPIRE nuclear reaction model code. The measured and calculated cross sections were used for deriving the thick-target yields and for estimating the production of other nuclides than {sup 177}Lu. Measured production cross sections of {sup 175,176,177,178}Ta on the same target are also presented.
There is an increasing interest in using radioisotopes of rare earth elements for internal radiotherapy and for imaging in nuclear medicine. "1"7"7Lu is one of the promising radionuclides. This article reports on the first measurements of the excitation function for the production of "1"7"7Lu with proton-beam energies up to 17 MeV on natural hafnium targets. The experimental cross sections for the reaction "n"a"tHf(p,x)"1"7"7Lu were obtained by the activation of a stacked-foil target and subsequent gamma spectrometry. Theoretical cross sections were calculated up to 35 MeV with the EMPIRE nuclear reaction model code. The measured and calculated cross sections were used for deriving the thick-target yields and for estimating the production of other nuclides than "1"7"7Lu. Measured production cross sections of "1"7"5","1"7"6","1"7"7","1"7"8Ta on the same target are also presented.
A dense and supersaturated nitrogen layer with higher conductivity is obtained on the surface of austenitic stainless steel 304L by the low temperature plasma nitriding. The effect of plasma nitriding on the corrosion behavior and interfacial contact resistance (ICR) for the austenitic stainless steel 304L was investigated in 0.05M H{sub 2}SO{sub 4}+2ppm F{sup -} simulating proton exchange membrane fuel cell (PEMFC) environment using electrochemical and electric resistance measurements. The experiment results show that the stable passive film is formed after the potentiostatic polarization at the specified anodic or cathodic potentials under PEMFC operation condition, and the plasma nitriding improves slightly the corrosion resistance and decreases markedly the ICR of 304L. The ICR of the plasma nitrided 304L increases after the potentiostatic polarizations for 4h, and lower than 100m{omega}cm{sup 2} at the compaction force of 150Ncm{sup -2}. (author)
The paper describes a concept of extracting fusion power from D-{sup 3}He fueled IEC (Inertia Electrostatic Configuration) devices. The fusion system consists of a series of fusion modules and direct energy converters at an end or at both ends. This system of multiple units is linear and is connected by a magnetic field. A pair of coils anti-parallel to the magnetic field yields a field-null domain at the center of each unit as required for IEC operation. A stabilizing coil installed between the coil pairs eliminates the strong attractive force between the anti-parallel coils. Accessible regions for charged particle trajectories are essentially isolated from the coil structure. Thus, charged particles are directed along magnetic field lines to the direct energy converter without appreciable losses. A direct energy converter unit designed to be compatible to this unique system is also described. It basically consists of a separator and a traveling wave converter. A separator separates ...
The purpose of this study is to develop the radioisotope tracer technology, which can be used in solving industrial and environmental problems and to build a strong tracer group to support the local industries. In relation to the tracer technology in 1999, experiments to estimate the efficiencies of a sludge digester of a waste water treatment plant and a submerged biological reactor of a dye industry were conducted. As a result, the tracer technology for optimization of facilities related to wastewater treatment has been developed and is believed to contribute to improve their operation efficiency. The quantification of the experimental result was attempted to improve the confidence of tracer technology by ECRIN program which basically uses the MCNP simulation principle. Using thin layer activation technique, wear of tappet shim was estimated. Thin layer surface of a tappet shim was irradiated by proton beam and the correlation between the measured activity loss ...
High-spin states of "1"8"7Ir have been populated in the "1"7"6Yb("1"5N,4n) reaction and measured with the YRAST Ball spectrometer. The #pi#h _9_/_2 rotational band has been extended beyond the first alignment crossing, which was found at rotational frequency (#Planck constant#/2#pi#)#omega# _c #approx =#0.39 MeV . Two different scenarios for describing this crossing are considered: the alignment of an h _9_/_2 proton or i _1_3_/_2 neutron pair and it is concluded that a proton band crossing is more likely. A systematic study of the rotational alignment crossings in the #pi#h _9_/_2 bands in the N=104,106,108 isotopes of _7_3Ta,_7_5Re,_7_7Ir, and _7_9Au is presented.
The flux of cosmic ray antiprotons with kinetic energies between /approximately/1 and 15 GeV is /approximately/5 times greater than the flux predicted on the basis of the leaky-box model. This excess is attributed to secondary antineutron production in compact sources. Because the antineutrons are not confined by the magnetic field of the compact source, they leave the interaction site, decay in interstellar space and account for the apparent excess cosmic ray antiproton flux. The escape and decay of neutrons produced in association with the antineutrons is a source of cosmic ray protons. Observations of the angular variation of the intensity and spectral shape of 100 MeV ..gamma..-rays produced by neutron-decay protons in the reaction p + p ..-->.. ..pi../sup 0/ ..-->.. 2..gamma.. could reveal compact-source cosmic ray production sites. COS-B observations of spectral hardening near point sources, and future high-resolution observations ...
A series of cation exchange membranes was produced by impregnating and coating both sides of a quartz web with a Nafion solution (1100 EW, 10%wt in water). Inert filler particles (SiO_2, ZrO_2 or TiO_2; 5-20%wt) were incorporated into the aqueous Nafion solution to produce robust, composite membranes. Ion-exchange capacity/equivalent weight, water take-up, thickness change on hydration and ionic and electrical conductivity were measured in 1 mol dm"-"3 sulfuric acid at 298 K. The TiO_2 filler significantly impacted on these properties, producing higher water take-up and increased conductivity. Such membranes may be beneficial for proton exchange membrane (PEM) fuel cell operation at low humidification. The PEM fuel cell performance of the composite membranes containing SiO_2 fillers was examined in a Ballard Mark 5E unit cell. While the use of composite membranes offers a cost reduction, the unit cell performance was reduced, in practice, due to drying of the ...
The nature of extralattice aluminum and its effect on acidity in zeolites was studied. A series of zeolites (some commercial), dealuminated by various methods, were obtained having Si/Al ratios between 1.5 and 20. These were characterized using volumetric sorption, XRD, AA, NMR, and reaction studies. Samples dealuminated using ammonium hexafluorosilicate were found to contain little or no extralattice aluminum. In contrast, steam-dealuminated zeolites had large amounts of extralattice aluminum. In some cases a significant portion of the extralattice aluminum was unobservable by [sup 27]Al NMR, suggesting the existence of an aluminum species of low symmetry. Proton NMR indicated that all the protons were associated with the lattice aluminum atoms. Depending on the preparation history, different groups of H-Y zeolites exhibited different maxima in catalytic activity as a function of aluminum content. The maxima in catalytic activity for n-pentane ...
High-resolution proton nuclear magnetic resonance spectroscopy has been used to investigate the molecular mechanism of the Bohr effect of human normal adult hemoglobin in the presence of two allosteric effectors, i.e., chloride and inorganic phosphate ions. The individual hydrogen ion equilibria of 22-26 histidyl residues of hemoglobin have been measured in anion-free 0.1 M HEPES buffer and in the presence of 0.18 M chloride or 0.1 M inorganic phosphate ions in both deoxy and carbonmonoxy forms. The results indicate that the #beta#2-histidyl residues are strong binding sites for chloride and inorganic phosphate ions in hemoglobin. The affinity of the #beta#2-histidyl residues for these anions is larger in the deoxy than in the carbonmonoxy form. Nevertheless, the contribution of these histidyl residues to the anion Bohr effect is small due to their low pK value in deoxyhemoglobin in anion-free solvents. The interactions of chloride and inorganic phosphate ions with ...
This dissertation describes a measurement of the rate ofnuclear muon capture by the proton, performed by the MuCap Collaborationusing a new technique based on a time projection chamber operating inultraclean, deuterium-depleted hydrogen gas at room temperature and 1 MPapressure. The hydrogen target's low gas density of 1 percent compared toliquid hydrogen is key to avoiding uncertainties that arise from theformation of muonic molecules. The capture rate was obtained from thedifference between the mu- disappearance rate in hydrogen--as determinedfrom data collected in the experiment's first physics run in fall2004--and the world averagefor the mu+ decay rate. After combining theresults of my analysis with the results from another independent analysisof the 2004 data, the muon capture rate from the hyperfine singlet groundstate of the mu-p atom is found to be Lambda_S = 725.0 +- 17.4 1/s, fromwhich the induced pseudoscalar coupling of the nucleon, ...
We have developed a Bragg curve counter (BCC) equipped with an active cathode to extend the energy acceptance to lower energies than for a conventional BCC to measure differential cross-sections of fragment production reactions induced by tens of MeV protons. The signal from the active cathode providing the timing signal of fragment incidence and the time difference signal between the cathode and anode gives information on the fragment range in the BCC on the basis of electron drift time. Utilization of the range information made possible identification of fragments less than 0.5 MeV/u that is lower than the identification threshold of a conventional BCC technique. After investigations on fundamental properties of a newly constructed BCC using heavy ion beams and alpha-particles, this method was applied successfully to a fragment production measurement for 70 MeV proton-induced reactions on carbon. With this technique, the energy threshold of ...
The isomeric and {beta}-decay properties of neutron-rich {sup 53-57}Sc and {sup 53,54}Ca nuclei near neutron number N = 32 are reported, and the low-energy level schemes of {sup 53,54,56}Sc and {sup 53-57}Ti are presented. The low-energy level structures of the {sub 21}Sc isotopes are discussed in terms of the coupling of the valence 1f{sub 7/2} proton to states in the corresponding {sub 20}Ca cores. Implications with respect to the robustness of the N = 32 subshell closure are discussed, as well as the repercussions for a possible N = 34 subshell closure.
The traveler participated in the discussions about the physics that can be learned in the experiments being planned, those presently running, or those recently completed by a growing number of major laboratories in Europe and the USA at the 'Workshop on NN Bremsstrahlung and Polarization Observables', where many representatives of these experimental programs were present. The traveler's research in this field is supported by a DOE Grant, and she has pioneered the early theoretical NN(lambda) treatments. In addition, she visited the Vrije University to collaborate with Professor Henk Blok on proton scattering from Zr-90 and neighboring nuclei. The traveler also visited NIKEF and discussed possible future experiments of mutual interest to be done at that laboratory.
The general usefulness of neutron activation analysis (NAA) for samples containing the platinum group elements (PGE) and Au, either as major or trace constituents, is discussed. Charged particle activation is shown to be a viable or complementary alternative. Proton (6-10 MeV) and alpha particle (9-15 MeV) beams, produced in a tandem Van de Graaff accelerator, have been established to be the most effective choice. By taking advantage of the Coulomb barrier effect and the fact that many charged particle induced reactions have relatively large threshold values, the same instrumental technique can be applied, with minor modifications, to a wide range of materials.
The general usefulness of neutron activation analysis (NAA) for samples containing the platinum group elements and Au, either as major or trace constituents, is discussed. Charged particle activation is shown to be a viable or complementary alternative. Proton (6-10 MeV) and alpha particle (9-15 MeV) beams, produced in a Tandem van de Graaff accelerator, have been established to be the most effective choice. By taking advantage of the Coulomb barrier effect and the fact that many charged particle induced reactions have relatively large threshold values, the same instrumental technique can be applied, with minor modifications, to a wide range of materials.
Physicists are no strangers to Feynman diagrams, but the meaning of the diagrams is not always clear, even to those who have used them. That confusion has deep roots, as Kaiser clearly and convincingly explains. To Feynman himself, a diagram depicted an actual physical process in space-time, such as the exchange of photons that occurs when an electron and proton collide. However, he also saw it as shorthand for the contributions to the amplitude of a physical process made by the element of the process it depicted. The best part of this new book covers the early history, social history and 'conceptual history' of Feynman diagrams. Disagreements and criticisms aside, the book will be invaluable to historians and sociologists of physics interested in the growth of Feynman diagrams. (U.K.)
The thermodynamics of protonation and europium(III) complex formation with substituted methane diphosphonic acids have been reported recently. These ligands form strong complexes with europium in moderately acidic solutions ((H{sup +}) {ge} 0.1 M), conditions not conducive to complexation by most carboxylate and aminopolycarboxylate ligands. A correlation of log {beta} vs pK{sub a} values for phosphonate and carboxylate ligands is used to explore the effect of ligand structure on complex stability. 5 refs., 1 fig.
The HARP experiment at CERN is performing extensive measurements of hadron production cross sections and secondary particle yields, in the momentum range 1.5-15 GeV/c, over the full solid angle and using a large set of cryogenic and solid targets. First measurements of hadron production cross-sections in the forward region are reported using an aluminium target 5% of an interaction length thick and a proton beam of 12.9 GeV/c. A preliminary analysis in the large angle region of elastic scattering events produced with the cryogenic hydrogen target at 3 GeV/c beam momentum is also presented.
A black neutron detector of novel design has been constructed and tested as a neutron flux monitor. The neutron time-of-flight (TOF) technique was used to measure the zero degree neutron spectrum from a subnanosecond pulsed proton beam on a thick metallic lithium target. We describe the detector, discuss the shielding arrangement and electronics, determine the low-energy cut-off. We calculate the efficiency, show spectra and compare measured zero degree differential cross-section of the {sup 7}Li(p, n{sub 0}){sup 7}Be reaction with recommended published cross-sections. (orig.).
The LHC is designed to provide proton beams of 7 TeV and nominal luminosity of 10**34 cm**-2s**-1. This objective is achieved at an affordable cost by pushing all major collider components to the limits of technology, by upgrading the existing CERN accelerators and infrastructure, and by involving the technical expertise, resources and dedication of accelerator laboratories world-wide. Following a decade of intensive R&D and technical validation of major collider systems, the LHC construction is now fully underway. Major industrial contracts have been awarded and are in execution for the procurement of the magnet, cryogenics and other systems. In this report, the status of the design and construction of the major LHC systems is presented.
We have synthesized ozone by irradiating thin solid films of oxygen and oxygen-water mixtures with 100 keV protons, motivated by recent reports of condensed O_3 on icy satellites in the outer Solar system. We measured the depth of the Hartley absorption band in the ultraviolet by reflectance spectroscopy and used it to quantify the column density of ozone. We analyzed the results using a three-component (O, O_2 and O_3) model that successfully explains the fluence dependence of ozone production.
In future experiments the readout electronics for pixel detectors is required to be resistant to a very high radiation level. In this paper we report on irradiation tests performed on several preFPIX2 prototype pixel readout chips for the BTeV experiment exposed to a 200MeVproton beam. The prototype chips have been implemented in commercial 0.25 {micro}m CMOS processes following radiation tolerant design rules. The results show that this ASIC design tolerates a large total radiation dose, and that radiation induced Single Event Effects occur at a manageable level.
We present numerical calculations for cesium and mercury to estimate the sensitivity of the scattering length to the variation of the fine structure constant alpha. The method used follows ideas Chin and Flambaum [Phys. Rev. Lett. 96, 230801 (2006)], where the sensitivity to the variation of the electron to proton mass ratio, beta, was considered. We demonstrate that for heavy systems, the sensitivity to variation of alpha is of the same order of magnitude as to variation of beta. Near narrow Feshbach resonances the enhancement of the sensitivity may exceed nine orders of magnitude.
The schematic model is extended to open-shell nuclei. The quasiparticle random-phase approximation plus core polarization are used to calculate multipole matrix elements M/sub n/ and M/sub p/. Calculated trends in the ratio of deformation parameters ..beta../sub n//..beta../sub p/ are compared with experimental ratios for several sets of isotopes and isotones. The systematics indicate a rather abrupt change toward equality of ..beta../sub n/ and ..beta../sub p/ when N or Z is changed from a closed-shell value.
Bulk properties such as the binding energies, r.m.s. radii and deformation parameters are calculated for the light (Z=2-8) even-mass nuclei using deformed relativistic mean-field theory. A comparison between L1, NL1 and NL2 parameter sets are given. The effects of pairing for open-shell nuclei have been investigated. The calculation is extended to nuclei near the proton- and neutron-drip line. Reasonable agreement with experiment is achieved for NL1 and NL2 parameter sets. (orig.).
The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide (HgI{sub 2}) is reviewed and in the case of CZT supplemented by new alpha particle data. CZT strip detectors exposed to intermediate energy (1.3 MeV) proton fluences exhibit increased interstrip leakage after 10{sup 10} p/cm{sup 2} and significant bulk leakage after 10{sup 12} p/cm{sup 2}. CZT exposed to 200MeVprotons shows a two-fold loss in energy resolution after a fluence of 5 {times} 10{sup 9} p/cm{sup 2} in thick (3 mm) planar devices but little effect in 2 mm devices. No energy resolution effects were noted from moderated fission spectrum of neutrons after fluences up to 10{sup 10} n/cm{sup 2}, although activation was evident. Exposures of CZT to 5 MeV alpha particle at fluences up to 1.5 {times} 10{sup 10} {alpha}/cm{sup 2} produced a near linear decrease in peak ...
Polymer electrolyte membrane fuel cells (PEMFCs) are energy conversion devices that produce electricity from a supply of fuel, such as hydrogen. One of the major challenges in achieving efficient energy conversion is the development of cost-effective materials that can act as electrocatalysts for PEMFCs. In this letter, we demonstrate that, instead of conventional noble metals, such as platinum, chromium nitride nanocrystals of fcc structure exhibit attractive catalytic activity for PEMFCs. Device testing indicates good stability of nitride nanocrystals in low temperature fuel cell operational environment.
Carrier-free "8"8Y radioisotope, which has the longest half life (T=106.6 d) of yttrium radioisotopes and is a #gamma#-ray emitter, was obtained by proton irradiation of strontium, followed by cooling for one month. Then, "8"8Y was purified by precipitating strontium as strontium nitrate and extracting yttrium with tri-n-butyl phosphate (TBP). The decontamination factor of strontium to yttrium was more than 4x10"3 and chemically pure yttrium radioisotope was obtained. (author) 6 refs.
#pi#"#+-# and K"#+-# cumulative production in pA #-># #pi#"#+-#+x and pA #-># K"#+-#+x reactions at 10.14 GeV proton beam energy on nuclei (Be-Ta) was invesigated. Measurements were conducted using FAS-1 focusing hadron spectrometer. Invariant cross sections of #pi#"#+-# and K"#+-# cumulative production, values of ratio of this cross sections, dependences of production cross sections for pions and kaons on cumulative number and mass number of nucleus target, as well as on transverse momentum are measured. Difference of cumulative meson spectra occurring in different nuclei fragmentation is discussed in terms of flucton model. 17 refs.; 14 figs.
The satellite-borne experiment PAMELA has been used to make a new measurement of the cosmic-ray antiproton flux and the antiproton-to-proton flux ratio which extends previously published measurements down to 60 MeV and up to 180 GeV in kinetic energy. During 850 days of data acquisition approximately 1500 antiprotons were observed. The measurements are consistent with purely secondary production of antiprotons in the galaxy. More precise secondary production models are required for a complete interpretation of the results.
Nuclear reaction cross-sections for stable strontium and cesium isotopes, which were calculated by different approaches, are compared to available experimental data. Neutron and proton induced reaction cross-sections for the long-lived radionuclides [sup 90]Sr and [sup 137]Cs have been calculated in the energy range from 1 MeV to 10 GeV. Recommendations concerning cross-section calculations for strontium and cesium isotopes at intermediate and high energies are given. (orig.)
Energy level schemes are derived from gamma spectroscopy of several medium-mass deformed nuclei by studying the decay or proton and #alpha# nuclear spectroscopic data. Some new isomeric studies are established among which is the 31 y "1"7"8Hf isomeric state for which Isup(#pi#), K was determined to be 16"+, 16. A four quasi-particle configuration was assigned to this state at 2447.5 +- 2.5 KeV. Atomic masses have been calculated from various measurements and, on the basis of mass formulae extrapolated to neighboring mass regions.
The neutron transition multipole moment, M/sub n/, for (0"+#->#2"+, 1.84 MeV) transition is inferred by measuring the (#alpha#,#alpha#') angular distribution at E/sub #alpha#/ = 50 MeV and comparing it with a microscopic distorted-wave Born approximation calculation. Proton transition densities are taken from electron scattering data. M/sub n//M/sub p/ is found to be substantially less than N/Z in agreement with the (p,p') result.
The first measurement of the pn{yields}d{omega} total cross-section has been achieved at mean excess energies Q{approx}28 and 57 MeV by using a deuterium cluster-jet target. The momentum of the fast deuteron was measured in the ANKE spectrometer at COSY-Juelich and that of the slow ''spectator'' proton (p{sub sp}) from the pd{yields}p{sub sp}d{omega} reaction in a silicon telescope placed close to the target. The cross-sections lie above those measured for pp{yields}pp{omega} but seem to be below theoretical predictions. (orig.)
The (p,n) cross section on "8"8Sr was measured for proton energies between 5.75 and 11 MeV. Overall resolution was sufficient to separate the "8"8Y ground state (J/sup #pi#/ = 4"-), the first excited state (J/sup #pi#/ = 5"-) at 0.232 MeV, and the second excited state (J/sup #pi#/ = 1"+) at 0.393 MeV. A Legendre polynomial fit was made to the angular distributions and the resulting integrated cross sections are shown. 1 figure.
A general relativistic model for the formation and acceleration of lowmass-loaded jets from systems containing accreting black holes is presented. The model is based on previous numerical results and theoretical studies in the Newtonian regime, but modified to include the effects of space-time curvature in the vicinity of the event horizon of a spinning black hole. It is argued that the boundary layer between the Keplerian accretion disk and the event horizon is best suited for the formation and acceleration of the accretion-powered jets in active galactic nuclei and micro-quasars. The model presented here is based on matching the solutions of three different regions: i- a weakly magnetized Keplerian accretion disk in the outer part, where the transport of angular momentum is mediated through the magentorotational instability, ii- a strongly magnetized, advection-dominated and turbulent-free boundary layer (BL) between the outer cold accretion disk and the event horizon and where the ...
The introduction prior to series of papers on the application of neutrons for materials science (MS) in this issue starts with a brief summary of neutron scattering research history in Japan; from the individual activity by Motoharu Kimura at RIKEN early around 1940s to those at present era of world leading neutron science facilities of both JRR3 research reactor and JPARC of the largest proton Accelerator complex in Tokai. Then physical properties of low energy neutrons applied to MS as well as such neutron sources are also reviewed (http://www.jstage.jst.go.jp/browse/jvsj2). (author)
Equivalent circuit and electrical parameters for H-doped NH_4UO_2PO_4.3H_2O self supported membranes have been determined by impedance spectroscopy. The measurements were carried out with a dry membrane, at different temperatures, and a wet membrane in contact with different electrolyte solutions. Resistance values for the dry membrane decrease with temperature increase, which agrees with the weak protonic character of the H-doped ammonium uranylphosphate. On the other hand, differences in the electrical parameters, depending on the electrolyte considered were also obtained and are attributed to different conduction mechanisms. (Author).
The nuclei {sup 81}Zr and {sup 85}Mo with T{sub z}=1/2 have been reinvestigated via their {beta}-delayed proton emissions with p-{gamma} coincidence measurement. The half-life of {sup 81}Zr has been measured to be 5.3{+-}0.5 s, which agrees with one of the two previous values. For {sup 85}Mo, the measured half-life is 3.2{+-}0.2 s, which revises the previous value. (orig.) With 3 figs., 12 refs.
The nuclei "8"1Zr and "8"5Mo with T_z=1/2 have been reinvestigated via their #beta#-delayed proton emissions with p-#gamma# coincidence measurement. The half-life of "8"1Zr has been measured to be 5.3#+-#0.5 s, which agrees with one of the two previous values. For "8"5Mo, the measured half-life is 3.2#+-#0.2 s, which revises the previous value. (orig.).
Cosmic rays at ground level have been collected using the NMSU/Wizard - MASS2 instrument. The 17-hr observation run was made on September 9. 1991 in Fort Sumner, New Mexico, Usa. Fort Sumner is located at 1270 meters a.s.l., corresponding to an atmospheric depth of about 887 g/cm{sup 2}. The geomagnetic cutoff is 4.5 GV/c. The charge ratio of positive and negative muons and the proton to muon ratio have been determined. These observations will also be compared with data collected at a higher latitude using the same basic apparatus.
In a (p,p') study of /sup 88/Sr at Esub(p) = 201 MeV both a large resonance centered at 9.4 MeV excitation energy and the known 1/sup +/ state at 3.486 MeV are excited. Several discrete states are observed in the resonance. The cross section of the whole resonance is 27% of a simple particle-hole prediction. The strength of the low-lying 1/sup +/ state is only about 15% of that calculated from a wave function including core-polarization contributions, whereas (e,e') scattering finds about 50%.
In a (p,p') study of "8"8Sr at Esub(p) = 201 MeV both a large resonance centered at 9.4 MeV excitation energy and the known 1"+ state at 3.486 MeV are excited. Several discrete states are observed in the resonance. The cross section of the whole resonance is 27% of a simple particle-hole prediction. The strength of the low-lying 1"+ state is only about 15% of that calculated from a wave function including core-polarization contributions, whereas (e,e') scattering finds about 50%. (orig.).
Electron scattering data have been used to obtain transition charge densities for the low-lying E2 transitions in /sup 88/Sr, /sup 89/Y, and /sup 90/Zr. These charge densities show a characteristic shape indicative of their microscopic constituency, modified by core-polarization effects. A good description of transitions in the even-even nuclei is obtained by using the measured single-particle transitions in /sup 89/Y as effective densities. .ID LV2086 .PG 19 22
"2H, "4He, "1"6O, "4"0Ca, "8"0Zr, "1"4"0Yb, "2"2"4112, "3"3"6168 nuclei are invesigated in terms of flucton model. Effective numbers of nuclear fluctons and deuterons are calculated. Values of complete effective numbers of low-radius deuterons and fluctons with S=1 spin and T=0 isospin are presented. Investigation results of inclusive reactions of quasi-elastic knock-out of deuterons by fast protons are discussed. 9 refs.; 1 fig.; 1 tab.
A study of the #pi#1g/sub 9/2/ orbit size in "8"8Sr, "9"0Zr, and "9"2Mo is presented. The rms radius for the point-proton density is extracted by studying transitions to 8"+ states in these nuclei. The radii are consistently larger than a value determined in a magnetic electron scattering experiment on "9"3Nb. A qualitative discussion of the ground state occupation of the #pi#1g/sub 9/2/ orbit based on the transition amplitudes to the 8"+ states is given.
Properties of unique parity states in odd-proton (/sub 77/Ir, /sub 79/Au) and odd-neutron nuclei (/sub 78/Pt) are investigated in the framework of the interacting boson-fermion approximation model. The core (boson)-particle (fermion) interaction is represented by a quadrupole-quadrupole interaction and an exchange term, which takes into account the effects of the Pauli exclusion principle. The even-even core nucleus is described in terms of the IBA-1 hamiltonian. The change in the properties of the corresponding odd-A nuclei can be interpreted in terms of a transition of the core hamiltonian between the O(6) and SU(3) limiting cases.
Properties of unique parity states in odd-proton (_7_7Ir, _7_9Au) and odd-neutron nuclei (_7_8Pt) are investigated in the framework of the interacting boson-fermion approximation model. The core (boson)-particle (fermion) interaction is represented by a quadrupole-quadrupole interaction and an exchange term, which takes into account the effects of the Pauli exclusion principle. The even-even core nucleus is described in terms of the IBA-1 hamiltonian. The change in the properties of the corresponding odd-A nuclei can be interpreted in terms of a transition of the core hamiltonian between the O(6) and SU(3) limiting cases. (orig.).
The structure of the low-lying levels of the [sup 91]Zr nucleus is discussed in a framework of the cluster-phonon coupling model. In order to describe simultaneously positive- and negative-parity states, octupole as well as quadrupole vibrations of the [sup 88]Sr core are allowed. The cluster states include two single protons coupled to a single neutron. The residual interaction among the cluster particles is assumed to be the modified surface [delta] interaction. Energy levels and electromagnetic properties are calculated and compared with the experimental data.
Chemical effects of L X-ray intensity ratios in niobium and molybdenum compounds were studied by electron and proton bombardments. L{sub {gamma}1} X-rays which involve transition of 4d electrons of the valence shell were found to be sensitive to the chemical environment. The L{sub {gamma}1}/L{sub {beta}1} X-ray intensity ratio increased with an increase of the 4d electron occupation of niobium or molybdenum in niobium or molybdenum compounds, showing that the chemical effects can be ascribed to the 4d electron behavior of the metallic atom in its compounds. (orig.).
Chemical effects of L X-ray intensity ratios in niobium and molybdenum compounds were studied by electron and proton bombardments. L_#gamma#_1 X-rays which involve transition of 4d electrons of the valence shell were found to be sensitive to the chemical environment. The L_#gamma#_1/L_#beta#_1 X-ray intensity ratio increased with an increase of the 4d electron occupation of niobium or molybdenum in niobium or molybdenum compounds, showing that the chemical effects can be ascribed to the 4d electron behavior of the metallic atom in its compounds. (orig.).
Historically the Los Alamos Spallation Radiation Effects Facility (LASREF) has used manual methods to control the position of the 800 kW, 800 MeV proton beam on targets. New experiments, however, require more stringent position control more frequently than can be done manually for long periods of time. Data from an existing harp is used to automatically adjust steering magnets to maintain beam position to required tolerances.
Alpha particles, tritons, deuterons and protons accompanying /sup 252/Cf fission were registered in coincidence with both fission fragments by means of a system containing two-dimensional position-sensitive silicon detectors. Angular distributions, kinetic energy spectra of light charged particles as well as mass distributions of fission fragments in coincidence with light charged particles were measured. The experimental results are compared with some theoretical models.
I review findings of various research groups regarding perturbative heterotic string model building in the last 12 months. Attention is given to recent studies of extra U(1)'s and local discrete symmetries (LDS's) in generic string models. Issues covered include the role of U(1)'s and LDS's in limiting proton decay, developments in classification of models containing anomalous U(1), and possible complications resulting from kinetic mixing between observable and hidden sector U(1)'s. Additionally, recent string-derived and string-inspired models are briefly reviewed. Talk Presented at SUSY '97.
A new potential function based on spectroscopic results for diatomic molecules is presented and applied to the hydrogen bonding systems. The potential energy of interaction is supposed to have electrostatic, polarization, dispersion, repulsion and effective charge-transfer contributions. Estimates of the effective charge-transfer quantity have been made based on the average charge of the proton donor and the acceptor atoms. For dimers such as water, methanol, acetic acid and formic acid, the vibrational stretching frequencies and dimerization energies are calculated and discussed in connection with Badger-Bauer rule. (author).
The isomeric and ?-decay properties of neutron-rich 53-57Sc and 53,54Ca nuclei near neutron number N=32 are reported, and the low-energy level schemes of 53,54,56Sc and 53-57Ti are presented. The low-energy level structures of the 21Sc isotopes are discussed in terms of the coupling of the valence 1f7/2 proton to states in the corresponding 20Ca cores. Implications with respect to the robustness of the N=32 subshell closure are discussed, as well as the repercussions for a possible N=34 subshell closure.
In the framework of spallation neutron sources and accelerator-driven systems, the international PISA (Proton-induced Spallation) collaboration has initiated measurements of total- and double-differential cross-sections for products of spallation reactions in a wide range of target nuclei (GU) at the COSY proton accelerator in Julich (Germany). The purpose is to study secondary particle production created in structural, window and target materials via proton beams up to 2.5 GeV of incident kinetic energy. Residual nuclei [H, He up to intermediate mass fragment (IMF)] production cross-sections are of great importance for estimating the damage to target and structure materials involving the planned spallation neutron sources, given that the lifetime of window and target materials is directly associated to those cross-sections. The demand for reliable theoretical predictions on production cross-sections is by no means ...
Measurements were made of the cross sections for the /sup 27/Al(/sup 16/O,/sup 15/N)/sup 28/Si, /sup 89/Y(/sup 15/N,/sup 16/O)/sup 88/Sr and /sup 89/Y(/sup 27/Al,/sup 28/Si)/sup 88/Sr reactions at energies near and below the Coulomb barrier. The first reaction required separate measurements of the transfer to elastic cross section ratio for particular charge states, the charge state distribution for /sup 27/Al and /sup 28/Si ions, and the absolute elastic scattering cross section for the /sup 27/Al + /sup 16/O system. The ratio measurement required the combined use of two relatively new scientific instruments: the momentum filter and the Bragg curve spectrometer. The latter two transfer measurements were performed using the same setup involving surface barrier detectors at backward angles. Additional elastic scattering data for the /sup 15/N + /sup 28/Si, /sup 89/Y + /sup 15/N, /sup 89/Sr + /sup 27/Al, and /sup 88/Sr + /sup 28/Si systems was collected to provide entrance and exit ...
Excitation functions, production yields and radionuclidic purities are described for "2"0"1Tl production by the "2"0"3Tl(p,3n) "2"0"1Pb #-># "2"0"1Tl and "2"0"5Tl(p,5n)"2"0"1Pb#->#"2"0"1Tl nuclear reactions. The yields (mCi g"-"1 cm"2/#mu#A-hr) of the parent "2"0"1Pb(9.4hr), as well as the radiocontaminants "2"0"0Pb(21.5hr), sup(202m)Pb(3.62 hr), "2"0"3Pb(52.1 hr) and sup(204m)Pb(1.115 hr) were measured by irradiating a stack of thin natural Tl foils with protons from the 76-in isochronous cyclotron at the Crocker Nuclear Laboratory. The "2"0"1Tl thick-target yield (mCi/#mu#A hr) was calculated for different target thicknesses and corresponding incident proton energies. The excitation functions for the "2"0"3Tl(p,3n)"2"0"1Pb and "2"0"5Tl(p,5n)"2"0"1Pb reactions were measured in the 15-60-MeV energy range. (author).
OAK B188 The goal of this project is to mimic the energy transduction processes by which photosynthetic organisms harvest sunlight and convert it to forms of energy that are more easily used and stored. The results may lead to new technologies for solar energy harvesting based on the natural photosynthetic process. They may also enrich our understanding and control of photosynthesis in living organisms, and lead to methods for increasing natural biomass production, carbon dioxide removal, and oxygen generation. In our work to date, we have learned how to make synthetic antenna and reaction center molecules that absorb light and undergo photoinduced electron transfer to generate long-lived, energetic charge-separated states. We have assembled a prototype system in which artificial reaction centers are inserted into liposomes (artificial cell-like constructs), where they carry out light-driven transmembrane translocation of hydrogen ions to generate proton motive ...
Assessment of the roles of the carboxyl-terminal #beta#146 histidyl residues in the alkaline Bohr effect in human and normal adult hemoglobin by high-resolution proton nuclear magnetic resonance spectroscopy requires assignment of the resonances corresponding to these residues. By a careful spectroscopic study of human normal adult hemoglobin, enzymatically prepared des(His146#beta#)-hemoglobin, and the mutant hemoglobins Cowtown (#beta#146His #-># Leu) and York (#beta#146His #-># Pro), the authors have resolved some of these conflicting results. By a close incremental variation of pH over a wide range in chloride-free 0.1 M N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid buffer, a single resonance has been found to be consistently missing in the proton nuclear magnetic resonance spectra of these hemoglobin variants. The results indicate that the contribution of the #beta#146 histidyl residues is 0.52 H"+/hemoglobin tetramer at pH ...
A balloon-borne instrument has measured the cosmic-ray antiproton flux between 130 and 320 MeV and searched for antihelium between 130 and 370 MeV per nuclear. These particles were selected from the background of normal-matter cosmic rays by combining a selective trigger with a detailed spark chamber visualization of each recorded event. Antiprotons are identified by their characteristic annihilatin radiation. Residue from background processes meeting the selection criteria is small. The observed 14 antiprotons yield a measured differential flux of 1.7 +- 0.5 x 10/sup -4/ antiprotons m/sup -2/ sr/sup -1/ s/sup -1/ MeV/sup -1/ at the top of the atmosphere. The corresponding antiproton/proton ratio is 2.2 +- 0.6 x 10/sup -4/,, only slightly smaller than the ratio observed by other experiments at higher energies. Thus the antiprotons have a spectral shape similar to the protons, at least down to about 100 MeV. The expected flux of these particles ...
It has been concluded by geologists that a significant amount of hydrogen is stored as point defects in nominally anhydrous minerals. Determination of the amount of hydrogen bound in these minerals is a step towards determining the total water content of the earth mantle as well as comprehending its internal water cycle. The possibility to measure hydrogen in thin geological samples by elastic p-p scattering has been investigated at the Lund Nuclear Microprobe. In this work the development of the experimental procedure and standardisation of data analysis is described. Special emphasis has been put into doing the data analysis as simple as possible and at the same time applicable to all sorts of thin samples, even those of unknown nature. A special annular surface barrier detector composed of two insulated detector halves, which are read out simultaneously, is used to detect the recoiled proton and the scattered proton in coincidence. ...
The effects of purified Helminthosporium maydis T (HmT) toxin on active Ca/sup 2 +/ transport into isolated mitochondria and microsomal vesicles were compared for a susceptible (T) and a resistant (N) strain of corn (Zea mays). ATP, malate, NADH, or succinate could drive /sup 45/Ca/sup 2 +/ transport into mitochondria of corn roots. Ca/sup 2 +/ uptake was dependent on the proton electrochemical gradient generated by the redox substrates or the reversible ATP synthetase, as oligomycin inhibited ATP-driven CA/sup 2 +/ uptake while KCN inhibited transport driven by the redox substrates. Purified native HmT toxin completely inhibited Ca/sup 2 +/ transport into T mitochondria at 5 to 10 nanograms per milliliter while transport into N mitochondria was decreased slightly by 100 nanograms per milliliter toxin. Malate-driven Ca/sup 2 +/ transport in T mitochondria was frequently more inhibited by 5 nanograms per milliliter toxin than succinate or ATP-driven Ca/sup 2 +/ ...
BaZr_0_._1Ce_0_._7Y_0_._2O_3_-_#delta# (BZCY7) exhibits adequate proton conductivity as well as sufficient chemical and thermal stability over a wide range of SOFC operating conditions, while layered GdBa_0_._5Sr_0_._5Co_2O_5_+_#delta# (GBSC) perovskite deposited on a doped ceria electrolyte demonstrates advanced electrochemical properties. This research fully takes advantage of these advanced properties and develops novel protonic ceramic membrane fuel cells (PCMFCs) of Ni-BZCY7|BZCY7|GBSC. The results show that the open-circuit potential of 1.003 V, maximum power density of 430 mW cm"-"2, and a low polarization resistance of the electrodes of 0.08 #OMEGA# cm"2 are achieved at 700 "oC. With temperature increases, the total cell resistance decreases, among which electrolyte resistance becomes increasingly dominant over polarization resistance. The results also indicate that GBSC perovskite cathode is a good candidate for intermediate ...
Host matrices for actinide immobilisation will undergo the formation of large helium quantities due to alpha decay. Helium diffusion rate has to be known in order to predict the long-term behaviour of the material, and particularly, the influence of helium accumulation on mechanical properties. A nuclear reaction analysis method, namely the "3He(d, p)"4He reaction, has been used to analyse the evolution of "3He profiles after ion implantations at 1 and 3 MeV in two materials, monoclinic ZrO_2 (as a test material) and Ca_9Nd(PO_4)_5(SiO_4)F_1_._5(OH)_0_._5 britholite (envisaged for Am and Pu long-term storage). Two data processing methods are used: the classical excitation curve (proton yields versus deuteron energy) and second, the proton energy spectrum for a given deuteron energy. The characteristics of the "3He profiles (depth, width) obtained by both methods are compared to SRIM estimations. Their evolution during subsequent annealings ...
New sets of cross sections for the production of krypton isotopes from targets of Rb, Sr, Y, and Zr were constructed primarily on the bases of experimental excitation functions for Kr production from Y. These cross sections were used to calculate galactic-cosmic-ray and solar-proton production rates for Kr isotopes in the moon. Spallation Kr data obtained from ilmenite separates of rocks 10017 and 10047 are reported. Production rates and isotopic ratios for cosmogenic Kr observed in ten well-documented lunar samples and in ilmenite separates and bulk samples from several lunar rocks with long but unknown irradiation histories were compared with predicted rates and ratios. The agreements were generally quite good. Erosion of rock surfaces affected rates or ratios for only near-surface samples, where solar-proton production is important. There were considerable spreads in predicted-to-observed production rates of /sup 83/Kr, due at least in part ...
The high energy limit of Quantum Chromodynamics is one of the most fascinating areas in the theory of strong interactions. Over a decade ago the HERA experiment at DESY in Hamburg provided strong evidence for the rise of the proton structure function at small values of the Bjorken variable x. This behavior can be explained as an increase of the gluon density of the proton with energy or correspondingly with smaller values of x. This increase can be attributed on the other hand to the large probability of gluon splitting in QCD. The natural framework for describing the gluon dynamics at small x is the Balitskii-Fadin-Kuraev-Lipatov formalism developed some 30 years ago. It predicts that the gluon density grows very fast with increasing energy, as a power with a large intercept. This increase has to be tamed in order to satisfy the unitarily bound. Over two decades ago, Gribov, Levin and Ryskin proposed the mechanism called the parton saturation, ...
We present a Poincare covariant Faddeev equation, which enables the simultaneous prediction of meson and baryon observables using the leading order in a truncation of the Dyson-Schwinger equations that can systematically be improved. The solution describes a nucleon's dressed-quark core. The evolution of the nucleon mass with current-quark mass is discussed. A nucleon-photon current, which can produce nucleon form factors with realistic Q{sup 2} evolution, is described. Axial-vector diquark correlations lead to a neutron Dirac form factor that is negative, with r{sub 1}{sup nu}>r{sub 1}{sup nd}. The proton electric-magnetic form factor ratio falls with increasing Q{sup 2}.
Recently we have made measurements of thermonuclear burst energetics and recurrence times which are unprecedented in their precision, largely thanks to the sensitivity of the Rossi X-ray Timing Explorer. In the "Clocked Burster", GS 1826-24, hydrogen burns during the burst via the rapid-proton (rp) process, which has received particular attention in recent years through theoretical and modelling studies. The burst energies and the measured variation of alpha (the ratio of persistent to burst flux) with accretion rate strongly suggests solar metallicity in the neutron star atmosphere, although this is not consistent with the corresponding variation of the recurrence time. Possible explanations include extra heating between the bursts, or a change in the fraction of the neutron star over which accretion takes place. I also present results from 4U 1746-37, which exhibits regular burst trains which are interrupted by "out of phase" bursts.
In this paper we discuss a number of astrophysical environments and how improved nuclear data could facilitate a better understanding of them. One area of interest includes proton and alpha-particle reactions with unstable nuclei which are necessary for understanding the nucleosynthesis and energy generation in hot hydrogen-burning environments. Efforts underway at LLNL and elsewhere to develop the technology for the measurement of these reaction rates are discussed. Heavy-element nucleosynthesis in the late stages of red-giant stars and supernovae requires a complete network of neutron capture rates and beta-decay rates for nuclei near and far from stability. Experimental and theoretical efforts at LLNL to supply the input data and to model the nucleosynthetic environments will be outlined. Suggestions are made as to which nuclear data are most critical for the various scenarios. 42 refs., 11 figs., 1 tab.
Bismuth radioisotopes, produced by 50-MeV proton bombardment of a lead target in a cyclotron, are separated from the lead target material by ion-exchange chromatography on a column containing 5.0 ml of Chelex 100. After a decay period of 24 hr, the /sup 203/Pb formed in situ is eluted from the column and then separated from /sup 200/Tl and /sup 201/Tl on a second ion-exchange column containing 0.5 ml of Chelex 100. Separations are sharp and carrier-free /sup 203/Pb is obtained.
In this paper it is shown that a measurement of the relative luminosity changes at the LHC may be obtained by analysing the currents drawn from the high voltage power supplies of the electromagnetic section of the forward calorimeter of the ATLAS detector. The method was verified with a reproduction of a small section of the ATLAS forward calorimeter using proton beams of known beam energies and variable intensities at the U-70 accelerator at IHEP in Protvino, Russia. The experimental setup and the data taking during a test beam run in April 2008 are described in detail. A comparison of the measured high voltage currents with reference measurements from beam intensity monitors shows a linear dependence on the beam intensity. The non-linearities are measured to be less than 0.5 % combining statistical and systematic uncertainties.
Monte Carlo calculations of proton irradiation of permanent magnets for the TRADE experiment have been performed. An irradiation dose of about 4´106 Gy/yr/mA has been estimated due to beam losses in normal operating conditions. Existing experimental results indicate that this irradiation level may induce a considerable demagnetization: in fact, a dose of 6´107 Gy induces a remanence loss of 0.3 % on samples of Sm2Co17 magnets, which are the most resistant type. More detailed calculations with the final design of the magnets and of the beam line are suggested, to determine if the irradiation levels allowed a reliable operation of the permanent magnets for the entire duration of the TRADE experiment. Damage and gas production rates have also been calculated; the values obtained are very low, thus confirming that the demagnetization process is in great part reversible.
This paper reports the chemical compositions of chicken-blood stone Ji Xue Shi measured by Proton Induced X-ray Emission (PIXE). The experimental result show that for the red portion of chicken-blood stone, the concentration of Hg is as high as 20 wt%, and the concentration of S can be above 10 wt%. For the non-red portion the main chemical compositions are Al{sub 2}O{sub 3} and SiO{sub 2}. The obtained chemical compositions are close to those of kaolinite for Balin chicken-blood stone, and of pyrophyllite for Changhua chicken-blood stone, respectively. So far many Changhua chicken-blood stones and Balin chicken-blood stones were found in China, the PIXE method can be used to explore the provenance of available chicken-blood stones. (author)
This document reproduces the final project of David San Fabian Ayuso, presented on May 26, 2005, for the obtention of the engineer degree of the Carlos III University of Madrid. A single-phase, isothermal model, including both electron and proton transport, is introduced for the simulation of polymer electrolyte fuel cells (PEM). The model is implemented in the commercial code Fluent 6.0, through the use of UDFs (User Defined Functions). In order to validate the model, a single canal of a PEM monocell is simulated in three dimensions. The obtained result are qualitatively satisfactory. It is observed that it is not essential to solve the current collectors when a monocell is considered (and not a stack). in the present study, the number of nodes is the computational grid appears to be too low in the membrane zone in order to make a complete validation of the model. (Author) 20 refs.
A more complete level scheme is presented here for the decay of [sup 187]Pt, incorporating many new lines and levels up to 2.4 MeV. Emphasis has been placed on the extraction of multipole mixing ratios from nuclear orientation data. Analysis of that data, however, required a more complete understanding of the level structure (including, in particular, branching ratios, conversion coefficients, and level feedings), prompting the collection of new spectroscopy data. The low-lying, positive-parity levels are described in terms of (odd-proton) single-particle Nilsson states coupled to a triaxial core. Multipole mixing ratios are compared to those calculated in the Particle-Plus-Triaxial-Rotor Model. (orig.).
A more complete level scheme is presented here for the decay of "1"8"7Pt, incorporating many new lines and levels up to 2.4 MeV. Emphasis has been placed on the extraction of multipole mixing ratios from nuclear orientation data. Analysis of that data, however, required a more complete understanding of the level structure (including, in particular, branching ratios, conversion coefficients, and level feedings), prompting the collection of new spectroscopy data. The low-lying, positive-parity levels are described in terms of (odd-proton) single-particle Nilsson states coupled to a triaxial core. Multipole mixing ratios are compared to those calculated in the Particle-Plus-Triaxial-Rotor Model. (orig.).
We discuss an experimental technique aimed at tagging electron neutrinos in multi-GeV artificial sources on an event-by-event basis. It exploits in a novel manner calorimetric and tracking technologies developed in the framework of the LHC experiments and of rare kaon decay searches. The setup is based on an instrumented decay tunnel equipped with tagging units that intercept secondary and tertiary leptons from the bulk of undecayed pi+ and protons. We show that the taggers are able to reduce the nue contamination originating from K_e3 decays by about one order of magnitude. Only a limited suppression (~60%) is achieved for nue produced by the decay-in-flight of muons; for moderate beam powers, similar performance as for K_e3 can be reached supplementing the tagging system with an instrumented beam dump.
Cosmic ray antiprotons provide an important probe for the study of cosmic ray propagation in the interstellar space and to investigate the existence of Galactic dark matter. The ARGO-YBJ experiment is observing the Moon shadow with high statistical significance at an energy threshold of a few hundred GeV. Using all the data collected until November 2009, we set two upper limits on the antip/p flux ratio: 5% at an energy of 1.4 TeV and 6% at 5 TeV with a confidence level of 90%. In the few-TeV range the ARGO-YBJ results are the lowest available, useful to constrain models for antiproton production in antimatter domains.
The determination of Li and proton-capture element abundances in globular cluster (GC) giants allows us to constrain several key questions on the multiple population scenarios in GCs, from formation and early evolution to pollution and dilution mechanisms. In this Letter, we present our results on Li abundances for a large sample of giants in the intermediate-metallicity GC NGC 6121 (M4), for which Na and O have been already determined by Marino et al. The stars analyzed are both below and above the red giant branch bump luminosity. We found that the first and second generation stars share the same Li content, suggesting that a Li production must have occurred. This provides strong observational evidence supporting the scenario in which asymptotic giant branch stars are GC polluters.
Durability is a major limitation of current proton exchange membrane fuel cells. Mechanical stress due to hygro-thermal cycling is one failure mechanism of the polymer electrolyte membrane. In previous work the cyclic rate, temperature, and hydration dependent elastic-viscoplastic mechanical behavior of Nafion has been extensively investigated in uniaxial and biaxial tension, serving as a data basis and means of validation for a three-dimensional constitutive model. Here, the important effect of loading via constrained swelling is studied. Specifically, two types of loading are investigated: partially constrained swelling via a bimaterial swelling test and hygro-thermal cycling within a fuel cell. The bimaterial swelling conditions are examined via experiments in conjunction with modeling....
Nitridation of Cr-bearing alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant CrN or Cr2N base surfaces of interest for a range of electrochemical devices, including fuel cells, batteries, and sensors. This paper presents results of exploratory studies of the nitridation of commercially available, high Cr (30-35wt%) Ni-Cr alloys and a ferritic high Cr (29wt%) stainless steel for proton exchange membrane fuel cell (PEMFC) bipolar plates. A high degree of corrosion resistance in sulfuric acid solutions designed to simulate bipolar plate conditions and low ICR values were achieved. Oxygen impurities in the nitriding environment were observed to play a significant role in the nitrided surface structures that formed, with detrimental effect...
The performance of scanning driver circuits fabricated with self-aligned aluminum gate polysilicon thin-film transistors (TFT's) is demonstrated. After the gate electrode patterning, the fabrication process temperature is kept below 400degC to enable the use of aluminum gate electrodes. The low-temperature crystallization phenomenon, which occurs when protons are implanted simultaneously with boron or phosphorus dopants, is employed to eliminate the 600degC activation-annealing process. A maximum clock frequency of about 2.0 MHz is achieved when the driver operating voltage is 24 V and the TFT channel length is 12 [mu]m. (author).
The performance of scanning driver circuits fabricated with self-aligned aluminum gate polysilicon thin-film transistors (TFT's) is demonstrated. After the gate electrode patterning, the fabrication process temperature is kept below 400degC to enable the use of aluminum gate electrodes. The low-temperature crystallization phenomenon, which occurs when protons are implanted simultaneously with boron or phosphorus dopants, is employed to eliminate the 600degC activation-annealing process. A maximum clock frequency of about 2.0 MHz is achieved when the driver operating voltage is 24 V and the TFT channel length is 12 #mu#m. (author).
Researchers report results from the Low Energy Antiproton Experiment (LEAP), a balloon-borne instrument which was flown in August, 1987. They found a value of 4.2 by 10-6 for the antiproton to proton ratio in the energy range from 120 MeV to 600 MeV at the top of the atmosphere. In particular, this experiment places an upper limit on the flux almost an order of magnitude below the reported flux of Buffington et al. This upper limit allows us to place significant constraints on both the primordial black hole and weakly interacting Majorana Fermion hypothesis, as well as on the low energy processes in more conventional models of galactic cosmic ray antiproton production.
The superconducting magnets and associated cryogenic components in A-sector represent the initial phase of installation of the Fermilab superconducting accelerator, designed to accelerate proton beams to energies of 1 TeV. Installation of the magnets, comprising one-eighth of the ring, was completed in December, 1981. Cooldown and power tests took place in the first half of 1982, concurrent with main ring use for 400 GeV high energy physics. The tests described in this paper involved 151 cryogenic components in the tunnel: 94 dipoles, 24 quadrupoles, 25 spool pieces, 3 feed cans, 4 turn-around boxes and 1 bypass. Refrigeration was supplied by three satellite refrigerators, the Central Helium Liquefier, and two compressor buildings. The magnets were powered by a single power supply.
Breath analysis could offer a non-invasive means of intravenous drug monitoring if robust correlations between drug concentrations in breath and blood can be established. In this study, propofol blood and breath concentrations were determined in an animal model under varying physiological conditions. Propofol concentrations in breath were determined by means of two independently calibrated analytical methods: continuous, real-time proton transfer reaction mass spectrometry (PTR-MS) and discontinuous solid-phase micro-extraction coupled with gas chromatography mass spectrometry (SPME-GC-MS). Blood concentrations were determined by means of SPME-GC-MS. Effects of changes in pulmonary blood flow resulting in a decreased cardiac output (CO) and effects of dobutamine administration resulting in...
Dimensioning of actinides waste packages for long duration storage has to take into account helium production from natural decay and release rates from the material. For the latter, we propose here an improved method for the determination of the helium diffusion coefficient in britholite, to be used for minor actinides storage. This work is based on results we previously published using the classical three steps method: "3He implantation on a Van de Graaff facility, "3He profile determination analysing the protons resulting from the "3He(d,p)"4He reaction in a nuclear microprobe, evolution of the helium profile during annealings. Taking explicitly into account the incident deuterons energy stragglings allows us to show that the implanted helium profiles are bimodal, each component leading to a different helium diffusion coefficient.
The radioactive isotopes of lead are reviewed with respect to their choice for in vitro tracer studies. The #gamma#-photon energy and absence of particle emission in the decay of "2"0"3Pb makes it particularly suitable for these applications. Reaction yields of "2"0"3Pb using "2"0"3Tl targets and proton, deuteron, "3He and "4He beams are listed. Using the preferred reaction "2"0"3Tl (d, 2n)"2"0"3Pb with a 15 MeV deuteron beam, yields of about 75 #mu#Ci #mu#Ahr"-"1, after chemical separation, are reported. Details of target design and chemical separation are given. (U.K.).
The spectrum of antiprotons from dark matter annihilation are calculated using the Lund Monte Carlo program, and simple analytic expressions for the spectrum and low-energy antiproton/proton ratio are derived. Comparing the results with recent upper limits on low energy antiprotons, it is concluded that the reported 4-13 GeV antiproton flux cannot be accounted for by dark matter annihilation. The new upper limits do not provide useful constraints on dark matter particles. They restrict the annihilation rate and imply that annihilation gamma ray and e(+) fluxes would be far below the fluxes produced by cosmic-ray collisions. It may be possible to look for a dark matter halo annihilation signal at antiprotons energies below 0.5 GeV, where the flux from cosmic-ray collisions is expected to be negligible. 32 references.
A means of determination of a ctive hydrogen of hydroxyl, carboxyl, sulfhydryl, amino, amido and sulfonamido groups by chemical ionization mass spectrometry using ammonia and trideuterioammonia as reagent gases is described. The method is based on exchange of active hydrogen for deuterium occurring during the chemical ionization process using trideuterioammonia, with comparison of m/z for ammonium adduct [M + NH1]+ and trideuterioammonium adduct [M--nH + nD + ND4]+, or of protonated molecular ion [M + H]+ and deuteronated molecular ion [M--nH + nD + D]+ yielding the number of active hydrogens. Applications have been made to several classes of biologically important compounds. PMID:427257
The description of the high energy particle telescope NINA for the study of cosmic ray nuclei is presented. The instrument will be installed on board of the Resource 01 satellite and will fly on a polar orbit at 690 Km. The telescope consists on a pile of 16 detecting planes each of them is composed by two silicon strip detectors with perpendicular strips and has a total area of 60x60mm{sup 2}. The experiment goals are the study of cosmic ray protons and nuclei in the energy range 12-100 MeV/amu. It will be sensitive to the anomalous component and will also make the observation of the large solar flare events and geophysical phenomena as well. This experiment is the first step of the program RIM whose goal is the satellite study of anti particles in primary cosmic rays.
We consider particle evaporation and fission of an ensemble of hot, rotating compound nuclei as a stochastic process. We derive a set of coupled differential equations formed by a Fokker-Planck equation describing fission, and master equations for calculating particle evaporation. From these equations, we are able to determine multiplicities of prefission neutrons, protons and {alpha}-particles, their energy spectra and their angular momentum distributions. A comparison of our results with experimental data provides us with information regarding the reduced friction coefficient {beta}, the fission barrier height and the level density parameter. For different iridium isotopes, ({sup 181,185,187}Ir), {sup 185}Os and {sup 158}Er, we obtain as an upper limit {beta}{<=}8.0x10{sup 21} s{sup -1}. (orig.).
We consider particle evaporation and fission of an ensemble of hot, rotating compound nuclei as a stochastic process. We derive a set of coupled differential equations formed by a Fokker-Planck equation describing fission, and master equations for calculating particle evaporation. From these equations, we are able to determine multiplicities of prefission neutrons, protons and #alpha#-particles, their energy spectra and their angular momentum distributions. A comparison of our results with experimental data provides us with information regarding the reduced friction coefficient #beta#, the fission barrier height and the level density parameter. For different iridium isotopes, ("1"8"1","1"8"5","1"8"7Ir), "1"8"5Os and "1"5"8Er, we obtain as an upper limit #beta##<=#8.0x10"2"1 s"-"1. (orig.).
Stationary target measurements of the nucleon form factors have been performed with high precision down to Q{sup 2} of {approx} 0.01 GeV{sup 2} for protons (G{sub E}{sup p}) and down to {approx} 0.1 GeV{sup 2} for neutrons (G{sub M}{sup n}). Conventional extraction using cross section and polarization measurement cannot be extended to very low values of Q{sup 2} due to inherent experimental limitations. We present a proposal for a new approach to a measurement, using colliding beams, which will extend the range of possible measurement at low Q{sup 2} by several orders of magnitude over stationary target limits.
Stationary target measurements of the nucleon form factors have been performed with high precision down to Q2 of ? 0.01 GeV2 for protons (GEp) and down to ? 0.1 GeV2 for neutrons (GMn). Conventional extraction using cross section and polarization measurement cannot be extended to very low values of Q2 due to inherent experimental limitations. We present a proposal for a new approach to a measurement, using colliding beams, which will extend the range of possible measurement at low Q2 by several orders of magnitude over stationary target limits.