Nuclear electric dipole moment with relativistic effects in Xe and Hg atoms

International Nuclear Information System (INIS)

Oshima, Sachiko; Fujita, Takehisa; Asaga, Tomoko

2007-01-01

The atomic electric dipole moment (EDM) is evaluated by considering the relativistic effects as well as nuclear finite size effects in Xe and Hg atomic systems. Due to Schiff's theorem, the first order perturbation energy of EDM is canceled out by the second order perturbation energy for the point nucleus. The nuclear finite size effects arising from the intermediate atomic excitations may be finite for deformed nucleus but it is extremely small. The finite size contribution of the intermediate nuclear excitations in the second order perturbation energy is completely canceled by the third order perturbation energy. As the results, the finite contribution to the atomic EDM comes from the first order perturbation energy of relativistic effects, and it amounts to around 0.3 and 0.4 percents of the neutron EDM d n for Xe and Hg, respectively, though the calculations are carried out with a simplified single-particle nuclear model. From this relation in Hg atomic system, we can extract the neutron EDM which is found to be just comparable with the direct neutron EDM measurement

Tensorial analysis of the long-range interaction between metastable alkaline-earth-metal atoms

International Nuclear Information System (INIS)

Santra, Robin; Greene, Chris H.

2003-01-01

Alkaline-earth-metal atoms in their lowest (nsnp) 3 P 2 state are exceptionally long lived and can be trapped magnetically. The nonspherical atomic structure leads to anisotropic long-range interactions between two metastable alkaline-earth-metal atoms. The anisotropy affects the rotational motion of the diatomic system and couples states of different rotational quantum numbers. This paper develops a tensorial decomposition of the most important long-range interaction operators, and a systematic inclusion of molecular rotations, in the presence of an external magnetic field. This analysis illuminates the nature of the coupling between the various degrees of freedom. The consequences are illustrated by application to a system of practical interest: metastable 88 Sr. Using atomic parameters determined in a nearly ab initio calculation, we compute adiabatic potential-energy curves. The anisotropic interatomic interaction, in combination with the applied magnetic field, is demonstrated to induce the formation of a long-range molecular potential well. This curve correlates to two fully polarized, low-field seeking atoms in a rotational s-wave state. The coupling among molecular rotational states controls the existence of the potential well, and its properties vary as a function of magnetic-field strength, thus allowing the scattering length in this state to be tuned. The scattering length of metastable 88 Sr displays a resonance at a field of 339 G

Collisional effects on metastable atom population in vapour generated by electron beam heating

International Nuclear Information System (INIS)

Dikshit, B; Majumder, A; Bhatia, M S; Mago, V K

2008-01-01

The metastable atom population distribution in a free expanding uranium vapour generated by electron beam (e-beam) heating is expected to depart from its original value near the source due to atom-atom collisions and interaction with electrons of the e-beam generated plasma co-expanding with the vapour. To investigate the dynamics of the electron-atom and atom-atom interactions at different e-beam powers (or source temperatures), probing of the atomic population in ground (0 cm -1 ) and 620 cm -1 metastable states of uranium was carried out by the absorption technique using a hollow cathode discharge lamp. The excitation temperature of vapour at a distance ∼30 cm from the source was calculated on the basis of the measured ratio of populations in 620 to 0 cm -1 states and it was found to be much lower than both the source temperature and estimated translational temperature of the vapour that is cooled by adiabatic free expansion. This indicated relaxation of the metastable atoms by collisions with low energy plasma electrons was so significant that it brings the excitation temperature below the translational temperature of the vapour. So, with increase in e-beam power and hence atom density, frequent atom-atom collisions are expected to establish equilibrium between the excitation and translational temperatures, resulting in an increase in the excitation temperature (i.e. heating of vapour). This has been confirmed by analysing the experimentally observed growth pattern of the curve for excitation temperature with e-beam power. From the observed excitation temperature at low e-beam power when atom-atom collisions can be neglected, the total de-excitation cross section for relaxation of the 620 cm -1 state by interaction with low energy electrons was estimated and was found to be ∼10 -14 cm 2 . Finally using this value of cross section, the extent of excitational cooling and heating by electron-atom and atom-atom collisions are described at higher e-beam powers

Search for electric dipole moment in 129Xe atom using active nuclear spin maser

Directory of Open Access Journals (Sweden)

Ichikawa Y.

2014-03-01

Full Text Available An experimental search for an electric dipole moment in the diamagnetic atom 129Xe is in progress through the precision measurement of spin precession frequency using an active nuclear spin maser. A 3He comagnetometer has been incorporated into the active spin maser system in order to cancel out the long-term drifts in the external magnetic field. Also, a double-cell geometry has been adopted in order to suppress the frequency shifts due to interaction with polarized Rb atoms. The first EDM measurement with the 129Xe active spin maser and the 3He comagnetometer has been conducted.

Three-Dimensional Atomic Structure of Metastable Nanoclusters in Doped Semiconductors

Science.gov (United States)

Couillard, Martin; Radtke, Guillaume; Knights, Andrew P.; Botton, Gianluigi A.

2011-10-01

Aberration-corrected scanning transmission electron microscopy is used to determine the atomic structure of nanoclusters of cerium dopant atoms embedded in silicon. By channeling electrons along two crystallographic orientations, we identify a characteristic zinc-blende chemical ordering within CeSi clusters coherent with the silicon host matrix. Strain energy limits the size of these ordered arrangements to just above 1 nm. With the local order identified, we then determine the atomic configuration of an individual subnanometer cluster by quantifying the scattering intensity under weak channeling condition in terms of the number of atoms. Analysis based on single-atom visualization also evidences the presence of split-vacancy impurity complexes, which supports the hypothesis of a vacancy-assisted formation of these metastable CeSi nanophases.

Interaction of rare gas metastable atoms

International Nuclear Information System (INIS)

Wang, A.Z.F.

1977-11-01

The physical and chemical properties of metastable rare gas atoms are discussed and summarized. This is followed by a detailed examination of the various possible pathways whereby the metastable's excess electronic energy can be dissipated. The phenomenon of chemi-ionization is given special emphasis, and a theoretical treatment based on the use of complex (optical) potential is presented. This is followed by a discussion on the unique advantages offered by elastic differential cross section measurements in the apprehension of the fundamental forces governing the ionization process. The methodology generally adopted to extract information about the interaction potential for scattering data is also systematically outlined. Two widely studied chemi-ionization systems are then closely examined in the light of accurate differential cross section measurements obtained in this work. The first system is He(2 3 S) + Ar for which one can obtain an interaction potential which is in good harmony with the experimental results of other investigators. The validity of using the first-order semiclassical approximation for the phase shifts calculation in the presence of significant opacities is also discussed. The second reaction studied is He*+D 2 for which measurements were made on both spin states of the metastable helium. A self-consistent interaction potential is obtained for the triplet system, and reasons are given for not being able to do likewise for the singlet system. The anomalous hump proposed by a number of laboratories is analyzed. Total elastic and ionization cross sections as well as rate constants are calculated for the triplet case. Good agreement with experimental data is found. Finally, the construction and operation of a high power repetitively pulsed nitrogen laser pumped dye laser system is described in great details. Details for the construction and operation of a flashlamp pumped dye laser are likewise given

Fast metastable hydrogen atoms from H2 molecules: twin atoms

Directory of Open Access Journals (Sweden)

Trimèche A.

2015-01-01

Full Text Available It is a difficult task to obtain “twin atoms”, i.e. pairs of massive particles such that one can perform experiments in the same fashion that is routinely done with “twin photons”. One possible route to obtain such pairs is by dissociating homonuclear diatomic molecules. We address this possibility by investigating the production of metastable H(2s atoms coming from the dissociation of cold H2 molecules produced in a Campargue nozzle beam crossing an electron beam from a high intensity pulsed electron gun. Dissociation by electron impact was chosen to avoid limitations of target molecular excited states due to selection rules. Detectors placed several centimeters away from the collision center, and aligned with respect to possible common molecular dissociation channel, analyze the neutral fragments as a function of their time-of-flight (TOF through Lyman-α detection. Evidence for the first time observed coincidence of pairs of H(2s atoms obtained this way is presented.

Multiperturber effects in the Faraday spectrum of Rb atoms immersed in a high-density Xe gas

Science.gov (United States)

Woerdman, J. P.; Blok, F. J.; Kristensen, M.; Schrama, C. A.

1996-02-01

We have measured the D1 and D2 Faraday spectrum and absorption spectrum of Rb atoms immersed in high-density Xe buffer gas in the range nXe=0.8-4.5×1020 cm-3. We find that the shape of the Faraday spectrum obeys the Becquerel relation over this whole density range; however the relative strength of the Faraday effect compared to absorption changes rather abruptly near nXe=1×1020 cm-3. This is ascribed to the onset of a many-body nature (overlapping collisions) of the Rb:Xe line broadening; the number of perturbers within the Weisskopf sphere is unity at nXe~1×1020 cm-3.

Beam experiments with state selected Ne (3P0, 3P2) metastable atoms

International Nuclear Information System (INIS)

Verheijen, M.J.

1984-01-01

Metastable rare gas atoms play an important role in all types of plasmas and gas discharges, e.g. in fluorescent lamps and in laser discharges (helium-neon laser or excimer lasers). In this thesis, the metastable states of NeI are studied. First, the theory of excited neon atoms and diatomic molecules is introduced, as well as Penning ionisation. Next, some experimental facilities are described (e.g. the dye laser system). With these instruments, natural lifetime measurements of the 2p fine structure states of NeI are carried out. Results are reported. Finally, total Penning ionisation cross sections are calculated using the optical potential model. (Auth.)

A novel Cs-(129)Xe atomic spin gyroscope with closed-loop Faraday modulation.

Science.gov (United States)

Fang, Jiancheng; Wan, Shuangai; Qin, Jie; Zhang, Chen; Quan, Wei; Yuan, Heng; Dong, Haifeng

2013-08-01

We report a novel Cs-(129)Xe atomic spin gyroscope (ASG) with closed-loop Faraday modulation method. This ASG requires approximately 30 min to start-up and 110 °C to operate. A closed-loop Faraday modulation method for measurement of the optical rotation was used in this ASG. This method uses an additional Faraday modulator to suppress the laser intensity fluctuation and Faraday modulator thermal induced fluctuation. We theoretically and experimentally validate this method in the Cs-(129)Xe ASG and achieved a bias stability of approximately 3.25 °∕h.

Photoionization of Xe inside C60: Atom-fullerene hybridization, giant cross-section enhancement, and correlation confinement resonances

International Nuclear Information System (INIS)

Madjet, Mohamed E.; Renger, Thomas; Hopper, Dale E.; McCune, Matthew A.; Chakraborty, Himadri S.; Rost, Jan-M.; Manson, Steven T.

2010-01-01

A theoretical study of the subshell photoionization of the Xe atom endohedrally confined in C 60 is presented. Powerful hybridization of the Xe 5s state with the bottom edge of C 60 π band is found that induces strong structures in the 5s ionization, causing the cross section to differ significantly from earlier results that omit this hybridization. The hybridization also affects the angular distribution asymmetry parameter of Xe 5p ionization near the Cooper minimum. The 5p cross section, on the other hand, is greatly enhanced by borrowing considerable oscillator strength from the C 60 giant plasmon resonance via the atom-fullerene dynamical interchannel coupling. Beyond the C 60 plasmon energy range the atomic subshell cross sections display confinement-induced oscillations in which, over the large 4d shape resonance region, the dominant 4d oscillations induce their ''clones'' in all degenerate weaker channels known as correlation confinement resonances.

Atomic approaches in metastable antiprotonic helium atoms. REPLY to 'analysis of the lifetimes and fractions of antiprotons trapped in metastable antiprotonic-helium states' by I. Shimamura and M. Kimura

International Nuclear Information System (INIS)

Yamazaki, Toshimitsu; Ohtsuki, Kazumasa.

1994-08-01

In the present note the authors clarify the purpose of YO and complement its essential points, thus showing that the criticisms of SK are inappropriate. The paper YO [1] was aimed at discussing some new aspects related to the metastability of hadronic helium atoms which had been discovered when negative kaons [2], negative pions [3] and antiprotons [4] were stopped in liquid helium. The delayed fraction, time spectrum shape and lifetimes were the observables. Further experimental studies are in progress [5], and as of today there is no successful explanation for these interesting phenomena. So, YO tried to give brief and rather qualitative estimates for the observations in an intuitive way, considering only the leading terms. The following problems are discussed in as simple a manner as possible, starting from the exotic-atom viewpoints of Condo [6] and Russell [7]: i)the atomic core polarization effect, ii)the structure and radiative lifetimes, iii)the non-statistical distribution of the angular momentum and an estimate of the delayed fraction, and iv)the isotope effect, though the title represents only i). To respond to the comments of SK, it is important to consider the correspondence between the atomic approach and the molecular approach for the metastable antiprotonic helium atom of Condo-Russell. We therefore begin this note with a discussion of this aspect. (author)

Inner-shell photoionization and core-hole decay of Xe and XeF2.

Science.gov (United States)

Southworth, Stephen H; Wehlitz, Ralf; Picón, Antonio; Lehmann, C Stefan; Cheng, Lan; Stanton, John F

2015-06-14

Photoionization cross sections and partial ion yields of Xe and XeF2 from Xe 3d(5/2), Xe 3d(3/2), and F 1s subshells in the 660-740 eV range are compared to explore effects of the F ligands. The Xe 3d-ϵf continuum shape resonances dominate the photoionization cross sections of both the atom and molecule, but prominent resonances appear in the XeF2 cross section due to nominal excitation of Xe 3d and F 1s electrons to the lowest unoccupied molecular orbital (LUMO), a delocalized anti-bonding MO. Comparisons of the ion products from the atom and molecule following Xe 3d photoionization show that the charge-state distribution of Xe ions is shifted to lower charge states in the molecule along with production of energetic F(+) and F(2+) ions. This suggests that, in decay of a Xe 3d core hole, charge is redistributed to the F ligands and the system dissociates due to Coulomb repulsion. The ion products from excitation of the F 1s-LUMO resonance are different and show strong increases in the yields of Xe(+) and F(+) ions. The subshell ionization thresholds, the LUMO resonance energies, and their oscillator strengths are calculated by relativistic coupled-cluster methods and agree well with measurements.

Energy-Transfer Kinetics for Xe (6p[1/2]0) Atoms in Kr, Ar, Ne, and He.

Science.gov (United States)

He, Shan; Liu, Dong; Li, Xueyang; Chu, Junzhi; Guo, Jingwei; Liu, Jinbo; Hu, Shu; Sang, Fengting; Jin, Yuqi

2018-06-11

The kinetic processes for the Xe (6p[1/2] 0 ) atoms in Kr, Ar, Ne, and He buffer gases were studied. We found that Kr, Ar, and Ne atoms can be used to switch the amplified spontaneous emission (ASE) channel from 3408 nm (6p[1/2] 0 -6s'[1/2] 1 ) to 3680 nm (5d[1/2] 1 -6p[1/2] 1 ), while Xe and He atoms do not show such a phenomenon. This ASE channel switch is mainly ascribed to the fast transfer of 6p[1/2] 0 → 5d[1/2] 1 . On the basis of the rate equations for two-state coupling (energy-transfer processes between the two states are very rapid), the reason why the ASE channel switch effect normally coincides with a double exponential decay of the spontaneous emission at 828 nm (6p[1/2] 0 -6s[3/2] 1 ) is explained. The actual situations in Xe, Ar, Ne, and He follow this rule. However, the strictly single exponential decay of the spontaneous emission at 828 nm and strong ASE channel switch effect simultaneously emerge in Kr. This indicates that the transfer of 6p[1/2] 0 → 5d[1/2] 1 in Kr does not occur via two-state coupling, but via two steps of near-resonance collision through the 5s[3/2] 2 (Kr) state as the intermediate state (6p[1/2] 0 → 5s[3/2] 2 (Kr) → 5d[1/2] 1 ). In addition, we found Xe (6p[1/2] 0 ) atoms strongly tend to reach the 6p[3/2] 2 , 6p[3/2] 1 , and 6p[5/2] 2 states through the 5s[3/2] 2 (Kr) state as the intermediate state in Kr. The 5s[3/2] 2 (Kr) state plays a very important role in the energy-transfer kinetics for the Xe (6p[1/2] 0 ) atoms. Kr is probably an excellent buffer gas for laser systems based on Xe.

Rb-129Xe spin-exchange rates due to binary and three-body collisions at high Xe pressures

International Nuclear Information System (INIS)

Cates, G.D.; Fitzgerald, R.J.; Barton, A.S.; Bogorad, P.; Gatzke, M.; Newbury, N.R.; Saam, B.

1992-01-01

We have studied the spin relaxation of 129 Xe nuclei due to collisions with Rb atoms at Xe pressures of 245--1817 Torr. Our results can be characterized by two parameters, the Rb- 129 Xe velocity-averaged binary spin-exchange cross section left-angle σv right-angle and a rate γ M that characterizes spin relaxation due to van der Waals molecules. Our results complement earlier studies performed at Xe pressures of about 1 Torr and N 2 pressures of 10--100 Torr. This work is useful for predicting spin-exchange rates between polarized Rb atoms and 129 Xe nuclei

X-ray laser implementation by means of a strong source of high-spin metastable atoms

International Nuclear Information System (INIS)

Helman, J.S.; Rau, C.; Bunge, C.F.

1983-01-01

High-spin metastable atomic beams of high density and extremely small divergence can be produced by electron capture during grazing-angle scattering of ion beams at ferromagnetic surfaces. This can be used to generate a long-lived reservoir of Li 1s2s2p 4 P/sub 5/2//sup ts0/ with enough density of metastables so that after laser-induced transfer to Li 1s2p/sup ts2/P strong lasing at 207 A should occur. This novel technique can also be used to produce a variety of other metastables known as potential candidates for lasing at shorter wavelengths

Demonstration of a CW diode-pumped Ar metastable laser operating at 4  W.

Science.gov (United States)

Han, J; Heaven, M C; Moran, P J; Pitz, G A; Guild, E M; Sanderson, C R; Hokr, B

2017-11-15

Optically pumped rare gas lasers are being investigated as potential high-energy, high beam quality systems. The lasing medium consists of rare gas atoms (Rg=Ne, Ar, Kr, or Xe) that have been electric discharge excited to the metastable np 5 (n+1)s P3 2 state. Following optical excitation, helium (He) at pressures of 200-1000 Torr is used as the energy transfer agent to create a population inversion. The primary technical difficulty for this scheme is the discharge production of sufficient Rg* metastables in the presence of >200  Torr of He. In this Letter, we describe a pulsed discharge that yields >10 13   cm -3 Ar* in the presence of He at total pressures up to 750 Torr. Using this discharge, a diode-pumped Ar* laser providing 4.1 W has been demonstrated.

Metastable argon atom density in complex argon/acetylene plasmas determined by means of optical absorption and emission spectroscopy

International Nuclear Information System (INIS)

Sushkov, Vladimir; Herrendorf, Ann-Pierra; Hippler, Rainer

2016-01-01

Optical emission and absorption spectroscopy has been utilized to investigate the instability of acetylene-containing dusty plasmas induced by growing nano-particles. The density of Ar(1s 5 ) metastable atoms was derived by two methods: tunable diode laser absorption spectroscopy and with the help of the branching ratio method of emitted spectral lines. Results of the two techniques agree well with each other. The density of Ar(1s 3 ) metastable atoms was also measured by means of optical emission spectroscopy. The observed growth instability leads to pronounced temporal variations of the metastable and other excited state densities. An analysis of optical line ratios provides evidence for a depletion of free electrons during the growth cycle but no indication for electron temperature variations. (paper)

First observation of laser-induced resonant annihilation in metastable antiprotonic helium atoms

International Nuclear Information System (INIS)

Morita, N.; Kumakura, M.; Yamazaki, T.

1993-11-01

We have observed the first laser-induced resonant transitions in antiprotonic helium atoms. These occur between metastable states and Auger dominated short lived states, and show that the anomalous longevity of antiprotons previously observed in helium media results from the formation of high-n high-l atomic states of p-barHe + . The observed transition with vacuum wavelength 597.259 ± 0.002 nm and lower-state lifetime 15 ± 1 ns is tentatively assigned to (n,l) = (39,35) → (38,34). (author)

Differential cross sections for inelastic scattering of electrons on Kr and Xe atoms at intermediate energies

International Nuclear Information System (INIS)

Filipovic, D.M.

1989-01-01

Electron-impact excitation of the larger- number noble-gas atoms is a way of understanding excitation mechanisms in atomic collisional processes. Krypton and xenon have the largest atomic number of all the stable noble gases. Therefore, effects dependent on the size of a target atom, such as alignment and orientation of the atomic outer shell charge cloud after collisional excitation, are best observed by studying these atoms. Normalized, absolute differential cross sections (DCS's) for the lowest electronic states of Kr and Xe atoms, at intermediate energies, are the subject of this report

The Decay of Optically Thick Helium Plasmas, Taking into Account Ionizing Collisions between Metastable Atoms or Molecules

International Nuclear Information System (INIS)

Stevefelt, J.

1970-11-01

The effective recombination rate of a helium afterglow plasma, which is optically thick towards the resonance lines, is calculated from the coupled rate equations for the number densities of free electrons and of metastable atoms or molecules. The model employed is a neutral plasma, consisting of one kind of ions and one kind of metastables. The ions are lost by electron-ion recombination only, with subsequent formation of metastables, which are then deactivated in collisions with free electrons or with other metastables: in the latter case one electron is regained to the free state. When the rate constants for these various processes are time-independent, it is found that after a certain transition time a transient equilibrium between the number densities of electrons and metastables is attained. In a dense afterglow plasma, where the recombination coefficient may be large, the transient equilibrium density of metastables may become significantly higher than the qua si-equilibrium value obtained by equating the time derivative of the metastable density to zero, and the effective recombination coefficient may be reduced by much more than a factor of two

The Decay of Optically Thick Helium Plasmas, Taking into Account Ionizing Collisions between Metastable Atoms or Molecules

Energy Technology Data Exchange (ETDEWEB)

Stevefelt, J

1970-11-15

The effective recombination rate of a helium afterglow plasma, which is optically thick towards the resonance lines, is calculated from the coupled rate equations for the number densities of free electrons and of metastable atoms or molecules. The model employed is a neutral plasma, consisting of one kind of ions and one kind of metastables. The ions are lost by electron-ion recombination only, with subsequent formation of metastables, which are then deactivated in collisions with free electrons or with other metastables: in the latter case one electron is regained to the free state. When the rate constants for these various processes are time-independent, it is found that after a certain transition time a transient equilibrium between the number densities of electrons and metastables is attained. In a dense afterglow plasma, where the recombination coefficient may be large, the transient equilibrium density of metastables may become significantly higher than the qua si-equilibrium value obtained by equating the time derivative of the metastable density to zero, and the effective recombination coefficient may be reduced by much more than a factor of two

Low energy collisions of spin-polarized metastable argon atoms with ground state argon atoms

Science.gov (United States)

Taillandier-Loize, T.; Perales, F.; Baudon, J.; Hamamda, M.; Bocvarski, V.; Ducloy, M.; Correia, F.; Fabre, N.; Dutier, G.

2018-04-01

The collision between a spin-polarized metastable argon atom in Ar* (3p54s, 3P2, M = +2) state slightly decelerated by the Zeeman slower-laser technique and a co-propagating thermal ground state argon atom Ar (3p6, 1S0), both merged from the same supersonic beam, but coming through adjacent slots of a rotating disk, is investigated at the center of mass energies ranging from 1 to 10 meV. The duration of the laser pulse synchronised with the disk allows the tuning of the relative velocity and thus the collision energy. At these sub-thermal energies, the ‘resonant metastability transfer’ signal is too small to be evidenced. The explored energy range requires using indiscernibility amplitudes for identical isotopes to have a correct interpretation of the experimental results. Nevertheless, excitation transfers are expected to increase significantly at much lower energies as suggested by previous theoretical predictions of potentials 2g(3P2) and 2u(3P2). Limits at ultra-low collisional energies of the order of 1 mK (0.086 μeV) or less, where gigantic elastic cross sections are expected, will also be discussed. The experimental method is versatile and could be applied using different isotopes of Argon like 36Ar combined with 40Ar, as well as other rare gases among which Krypton should be of great interest thanks to the available numerous isotopes present in a natural gas mixture.

Collisional energy dependence of molecular ionization by metastable rare gas atoms

International Nuclear Information System (INIS)

Martin, R.M.; Parr, T.P.

1979-01-01

The collisional energy dependence of several molecular total ionization cross sections by metastable rare gas atoms was studied over the thermal energy region using the crossed molecular beam time-of-flight method. Results are reported for the collision systems He, Ne, and Ar ionizing the geometric isomers cis- and trans-dichloroethylene and ortho- and para-dichlorobenzene. The He ionization cross sections oscillate about an energy dependence of E/sup -1/2/ over the energy range 0.004--1.0 eV, and the Ar*+para-dichlorobenzene cross section oscillates about an energy dependence of E/sup -2/5/ over the energy range 0.011--0.64 eV. The remaining systems are characterized by ''bent'' E/sup -m/ dependences with m values of 0.56--0.70 at low energies changing to 0.07--0.29 at higher energies. Comparison with the slopes of the He* systems and the Ar*+para-dichlorobenzene system shows that the ''bent'' and ''oscillating'' energy dependences are similar except for the form of the cross section functions at the lowest energies. No systematic differences are found between the cross section energy dependences for ionization of different geometric isomers or for ionization by the different metastable rare gas atoms

Study of total ionization by {alpha} particles, in pure gases and gaseous mixtures containing metastable atoms, as a function of temperature; Etude de l'ionisation totale par les paricules {alpha}, dans les gaz purs et les melanges gazeux contenant des atomes metastables, en fonction de la temperature

Energy Technology Data Exchange (ETDEWEB)

Bristeau, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1969-07-01

Experiments have been carried out on the total ionization by alpha particles, in pure gases and gaseous mixtures containing metastable atoms, as a function of temperature. Using a different experimental method, the results for the mean ionization energy at 300 K given by Jesse in 1953 have been confirmed to within 1 per cent. It is established that in pure gases the mean energy W required to form a pair of ions remains constant as the temperature varies from 77 to 300 K. It is shown that there is a temperature effect for W in binary gas mixtures of the type A-B containing meta-stable atoms A{sup *} and an 'impurity' B. A systematic study is made of the change {delta}W in W as a function of the temperature and of the B 'impurity' concentration in the mixtures Ne - Ar, Ne - Kr, Ne - H{sub 2}, Ne - N{sub 2}, Ne - CH{sub 4} and He - Ar. Experiments have been carried out on a ternary gas mixture of the type A - B - C, where C is a second ionizable 'impurity' added to the binary mixture A - B; they show the existence of excited atoms B{sup *} formed from the 'impurity' B. Finally, it is shown that the amount of metastable atoms formed in a pure gas must be very close to the number N{sub 0} of ion pairs, and that there must exist a correlation between the number N{sub 0} of ion pairs and the number {approx_equal} N{sub 0} of metastable atoms created in the pure rare gases. (author) [French] On realise des experiences sur l'ionisation totale par les particules alpha, dans les gaz purs et les melanges gazeux contenant des atomes metastables, en fonction de la temperature. Avec une methode experimentale differente, on retrouve a mieux que 1 pour cent pres les valeurs de l'energie moyenne d'ionisation que JESSE a obtenues en 1953 et a 300 K. On etablit que dans les gaz purs, l'energie moyenne W pour creer une paire d'ions demeure constante, quand la temperature varie entre 77 et 300 K. On met en evidence un effet de temperature sur W, dans les melanges gazeux binaires du type

Determination of Ar metastable atom densities in Ar and Ar/H2 inductively coupled low-temperature plasmas

International Nuclear Information System (INIS)

Fox-Lyon, N; Knoll, A J; Oehrlein, G S; Franek, J; Demidov, V; Koepke, M; Godyak, V

2013-01-01

Ar metastable atoms are important energy carriers and surface interacting species in low-temperature plasmas that are difficult to quantify. Ar metastable atom densities (N Ar,m ) in inductively coupled Ar and Ar/H 2 plasmas were obtained using a model combining electrical probe measurements of electron density (N e ) and temperature (T e ), with analysis of spectrally resolved Ar plasma optical emission based on 3p → 1s optical emission ratios of the 419.8 nm line to the 420.1 nm line. We present the variation of N Ar,m as the Ar pressure and the addition of H 2 to Ar are changed comparatively to recent adsorption spectroscopy measurements. (paper)

Syntheses, Raman spectra, and X-ray crystal structures of [XeF(5)][mu-F(OsO(3)F(2))(2)] and [M][OsO(3)F(3)] (M = XeF(5)(+), Xe(2)F(11)(+)).

Science.gov (United States)

Hughes, Michael J; Mercier, Hélène P A; Schrobilgen, Gary J

2010-04-05

Stoichiometric amounts of XeF(6) and (OsO(3)F(2))(infinity) react at 25-50 degrees C to form salts of the known XeF(5)(+) and Xe(2)F(11)(+) cations, namely, [XeF(5)][mu-F(OsO(3)F(2))(2)], [XeF(5)][OsO(3)F(3)], and [Xe(2)F(11)][OsO(3)F(3)]. Although XeF(6) is oxophilic toward a number of transition metal and main-group oxides and oxide fluorides, fluoride/oxide metathesis was not observed. The series provides the first examples of noble-gas cations that are stabilized by metal oxide fluoride anions and the first example of a mu-F(OsO(3)F(2))(2)(-) salt. Both [XeF(5)][mu-F(OsO(3)F(2))(2)] and [Xe(2)F(11)][OsO(3)F(3)] are orange solids at room temperature. The [XeF(5)][OsO(3)F(3)] salt is an orange liquid at room temperature that solidifies at 5-0 degrees C. When the salts are heated at 50 degrees C under 1 atm of N(2) for more than 2 h, significant XeF(6) loss occurs. The X-ray crystal structures (-173 degrees C) show that the salts exist as discrete ion pairs and that the osmium coordination spheres in OsO(3)F(3)(-) and mu-F(OsO(3)F(2))(2)(-) are pseudo-octahedral OsO(3)F(3)-units having facial arrangements of oxygen and fluorine atoms. The mu-F(OsO(3)F(2))(2)(-) anion is comprised of two symmetry-related OsO(3)F(2)-groups that are fluorine-bridged to one another. Ion pairing results from secondary bonding interactions between the fluorine/oxygen atoms of the anions and the xenon atom of the cation, with the Xe...F/O contacts occurring opposite the axial fluorine and from beneath the equatorial XeF(4)-planes of the XeF(5)(+) and Xe(2)F(11)(+) cations so as to avoid the free valence electron lone pairs of the xenon atoms. The xenon atoms of [XeF(5)][mu-F(OsO(3)F(2))(2)] and [Xe(2)F(11)][OsO(3)F(3)] are nine-coordinate and the xenon atom of [XeF(5)][OsO(3)F(3)] is eight-coordinate. Quantum-chemical calculations at SVWN and B3LYP levels of theory were used to obtain the gas-phase geometries, vibrational frequencies, and NBO bond orders, valencies, and NPA charges of

Enhanced creation of dispersive monolayer phonons in Xe/Pt(111) by inelastic helium atom scattering at low energies

DEFF Research Database (Denmark)

Hansen, Flemming Yssing; Bruch, Ludwig Walter

2007-01-01

Conditions likely to lead to enhanced inelastic atomic scattering that creates shear horizontal (SH) and longitudinal acoustic (LA) monolayer phonons are identified, specifically examining the inelastic scattering of He-4 atoms by a monolayer solid of Xe/Pt(111) at incident energies of 2-25 meV. ...

Measurement of cross-sections for step-bystep excitation of inert gas atoms from metastable states by electron collisions

International Nuclear Information System (INIS)

Mityureva, A.A.; Penkin, N.P.; Smirnov, V.V.

1989-01-01

Excitation of argon atoms by electron collisions from metastable (MS) to high-lying states of inert gases (the so-called step-by-step excitation) is investigated. Formation of MS atoms m and their further step-by-step excitation up to k level is carried out by an electron beam with energy from 1 up to 40 eV. Time distribution of forming metastable and step-by-step electron collisions is used. The method used permits to measure the functions of step-by-step excitation and the absolute values of cross sections. Absolute values of cross-sections and functions of step-by-step excitation of some lines and argon levels are obtained

Study of the metastable singlet of molecular nitrogen and of oxygen atoms in discharges and post-discharges

International Nuclear Information System (INIS)

Magne, Lionel

1991-01-01

Whereas discharges in nitrogen, in oxygen and in their mixtures are used in many different industrial processes (surface treatment, nitridation, oxidation, and so on), in order to get a better knowledge on nitrogen electronic states, this research thesis reports the study of the metastable singlet state of molecular nitrogen, and of oxygen atoms in their fundamental state. The molecular metastable has been observed by far-UV optical emission spectroscopy, in the positive column of a continuous discharge and in time post-discharge. As far as continuous discharge is concerned, the author measured the vibrational distribution of this state. A kinetic model has been developed, and calculated vibrational distributions are in good agreement with measurements. The density of oxygen atoms in fundamental state in time post-discharge has been measured by far-UV absorption optical spectroscopy. The probability of atom re-association of glass walls is deduced from the obtained results [fr

Properties of the triplet metastable states of the alkaline-earth-metal atoms

International Nuclear Information System (INIS)

Mitroy, J.; Bromley, M.W.J.

2004-01-01

The static and dynamic properties of the alkaline-earth-metal atoms in their metastable state are computed in a configuration interaction approach with a semiempirical model potential for the core. Among the properties determined are the scalar and tensor polarizabilities, the quadrupole moment, some of the oscillator strengths, and the dispersion coefficients of the van der Waals interaction. A simple method for including the effect of the core on the dispersion parameters is described

Enhanced atom mobility on the surface of a metastable film.

Science.gov (United States)

Picone, A; Riva, M; Fratesi, G; Brambilla, A; Bussetti, G; Finazzi, M; Duò, L; Ciccacci, F

2014-07-25

A remarkable enhancement of atomic diffusion is highlighted by scanning tunneling microscopy performed on ultrathin metastable body-centered tetragonal Co films grown on Fe(001). The films follow a nearly perfect layer-by-layer growth mode with a saturation island density strongly dependent on the layer on which the nucleation occurs, indicating a lowering of the diffusion barrier. Density functional theory calculations reveal that this phenomenon is driven by the increasing capability of the film to accommodate large deformations as the thickness approaches the limit at which a structural transition occurs. These results disclose the possibility of tuning surface diffusion dynamics and controlling cluster nucleation and self-organization.

Modification of the Xe 4d giant resonance by the C60 shell in molecular Xe at C60

International Nuclear Information System (INIS)

Amusia, M. Ya.; Baltenkov, A. S.; Chernysheva, L. V.; Felfli, Z.; Msezane, A. Z.

2006-01-01

It is demonstrated that in photoabsorption of the 4d 10 subshell of a Xe atom in molecular Xe at C 60 , the 4d giant resonance that characterizes the isolated Xe atom is distorted significantly. The reflection of photoelectron waves by the C 60 shell leads to profound oscillations in the photoionization cross section such that the Xe giant resonance is transformed into four strong peaks. Similarly, the angular anisotropy parameters, both dipole and nondipole, are also modified. The method of calculation is based on the approximation of the C 60 shell by an infinitely thin bubble potential that leaves the sum rule for the 4d-electrons almost unaffected, but noticeably modifies the dipole polarizability of the 4d-shell

Metastable states in antiprotonic helium atoms an island stability in a sea of continuum

CERN Document Server

Korobov, V I

2002-01-01

In this contribution we consider a phenomenon of metastable states in antiprotonic helium atoms, precise spectroscopy of these states and a present-day study of the electromagnetic properties of antiprotons. Calculation of nonrelativistic energies, relativistic and QED corrections as well as the fine and hyperfine structure and the magnetic moment of an antiproton are the main parts of this study. Refs. 22 (nevyjel)

Molecular dynamics simulation of Xe bubble nucleation in nanocrystalline UO2 nuclear fuel

International Nuclear Information System (INIS)

Moore, Emily; René Corrales, L.; Desai, Tapan; Devanathan, Ram

2011-01-01

Highlights: ► We simulated the interactions of defects and fission gas with grain boundaries in nuclear fuel. ► We observed the formation of Xe bubble nuclei that are difficult to observe experimentally. ► The bubble nuclei form by vacancy-assisted diffusion of Xe atoms. ► We also observed the initial stages of grain boundary motion. ► The study offers insights to the design of nuclear fuel to control fission gas release. - Abstract: We have performed molecular dynamics (MD) simulations to investigate the dynamical interactions between vacancy defects, fission gas atoms (Xe), and grain boundaries in a model of polycrystalline UO 2 nuclear fuel with average grain diameter of about 20 nm. We followed the mobility and aggregation of Xe atoms in the vacancy-saturated model compound for up to 2 ns. During this time we observed the aggregation of Xe atoms into nuclei, which are possible precursors to Xe bubbles. The nucleation was driven by the migration of Xe atoms via vacancy-assisted diffusion. The Xe clusters aggregate faster than grain boundary diffusion rates and are smaller than experimentally observed bubbles. As the system evolves towards equilibrium, the Xe atom cluster growth slows down significantly, and the lattice relaxes around the cluster. These simulations provide insights into fundamental physical processes that are inaccessible to experiment.

Inner-shell spectroscopy and exchange interaction of Rydberg electrons bound by singly and doubly charged Kr and Xe atoms in small clusters

International Nuclear Information System (INIS)

Nagasaka, Masanari; Hatsui, Takaki; Setoyama, Hiroyuki; Ruehl, Eckart; Kosugi, Nobuhiro

2011-01-01

Surface-site resolved Kr 3d 5/2 -1 5p and 3d 5/2 -1 6p and Xe 4d 5/2 -1 6p and 4d 5/2 -1 7p Rydberg excited states in small van der Waals Kr and Xe clusters with a mean size of = 15 are investigated by X-ray absorption spectroscopy. Furthermore, surface-site resolved Kr 4s -2 5p, 4s -2 6p, and 4s -1 4p -1 5p shakeup-like Rydberg states in small Kr clusters are investigated by resonant Auger electron spectroscopy. The exchange interaction of the Rydberg electron with the surrounding atoms and the induced polarization of the surrounding atoms in the singly and doubly ionized atoms are deduced from the experimental spectra to analyze different surface-site contributions in small clusters, assuming that the corner, edge, face, and bulk sites have 3, 5-6, 8, and 12 nearest neighbor atoms. These energies are almost proportional to the number of the nearest neighbor atoms. The present analysis indicates that small Kr and Xe clusters with = 15 have an average or mixture structure between the fcc-like cubic and icosahedron-like spherical structures.

Fragmented metastable states exist in an attractive bose-einstein condensate for atom numbers well above the critical number of the Gross-Pitaevskii theory.

Science.gov (United States)

Cederbaum, Lorenz S; Streltsov, Alexej I; Alon, Ofir E

2008-02-01

It is well known that attractive condensates do not posses a stable ground state in three dimensions. The widely used Gross-Pitaevskii theory predicts the existence of metastable states up to some critical number N(cr)(GP) of atoms. It is demonstrated here that fragmented metastable states exist for atom numbers well above N(cr)(GP). The fragments are strongly overlapping in space. The results are obtained and analyzed analytically as well as numerically. The implications are discussed.

Quadrupole photoionization of endohedral Xe-C60

International Nuclear Information System (INIS)

Govil, Karan; Deshmukh, P C

2009-01-01

The effect of an endohedral confinement on the quadrupole photoionization of atomic Xe is studied using the relativistic random phase approximation (RRPA). The atom's confinement is modelled by placing atomic Xe at the centre of a C 60 cage represented by an annular potential around it. A new confinement resonance is reported in the 4p quadrupole cross-section along with 'correlation confinement resonances' in 4d, 5s and 5p photoionizations at about 185 eV. The effect of the confinement on the non-dipole photoelectron angular distribution parameter γ is also reported.

Electronic Spectroscopy of B Atoms and B2 Molecules Isolated in Para-H2, Normal-D2, Ne, Ar, Kr, and Xe Matrices

National Research Council Canada - National Science Library

Tam, Simon

2000-01-01

...), Ne, Ar, Kr, and Xe matrices, and of B2 molecules in Ne, Ar, Kr, and Xe matrices. The 2s(sup 2)3s((sup 2)S) left arrow 2s(sup 2)2p((sup 2)P) B atom Rydberg absorption suffers large gas-to-matrix blue shifts, increasing...

Detonation of Meta-stable Clusters

Energy Technology Data Exchange (ETDEWEB)

Kuhl, Allen; Kuhl, Allen L.; Fried, Laurence E.; Howard, W. Michael; Seizew, Michael R.; Bell, John B.; Beckner, Vincent; Grcar, Joseph F.

2008-05-31

We consider the energy accumulation in meta-stable clusters. This energy can be much larger than the typical chemical bond energy (~;;1 ev/atom). For example, polymeric nitrogen can accumulate 4 ev/atom in the N8 (fcc) structure, while helium can accumulate 9 ev/atom in the excited triplet state He2* . They release their energy by cluster fission: N8 -> 4N2 and He2* -> 2He. We study the locus of states in thermodynamic state space for the detonation of such meta-stable clusters. In particular, the equilibrium isentrope, starting at the Chapman-Jouguet state, and expanding down to 1 atmosphere was calculated with the Cheetah code. Large detonation pressures (3 and 16 Mbar), temperatures (12 and 34 kilo-K) and velocities (20 and 43 km/s) are a consequence of the large heats of detonation (6.6 and 50 kilo-cal/g) for nitrogen and helium clusters respectively. If such meta-stable clusters could be synthesized, they offer the potential for large increases in the energy density of materials.

Properties of excited xenon atoms in a plasma display panel

International Nuclear Information System (INIS)

Uhm, Han S.; Hong, Byoung H.; Oh, Phil Y.; Choi, Eun H.

2009-01-01

The luminance efficiency of a plasma display panel is directly related to the vacuum ultraviolet (VUV) light that is emitted from excited xenon (Xe) atoms and molecules. It is therefore necessary to investigate the properties of excited xenon atoms. This study presents experimental data associated with the behavior of excited xenon atoms in a PDP discharge cell and compares the data with the theoretical results obtained using an analytical model. The properties of excited xenon atoms in the discharge cells of a plasma display panel are investigated by measuring the excited atom density through the use of laser absorption spectroscopy. The density of the excited xenon atoms increases from zero, reaches its peak, and decreases with time in the discharge cells. The profile of the excited xenon atoms is also studied in terms of the xenon mole fraction. The typical density of the excited xenon atoms in the metastable state is on the order of 10 13 atoms per cubic cm.

Metastable hydrogen

International Nuclear Information System (INIS)

Dose, V.

1982-01-01

This paper deals with the basic physical properties of the metastable 2 2 sub(1/2) state of atomic hydrogen. Applications relying on its special properties, including measurement of the Lamb shift, production of spin-polarized protons and the measurement of molecular electric moments, are discussed. (author)

Fixed energy inversion of 5 eV e-Xe atom scattering

International Nuclear Information System (INIS)

Lovell, A.; Amos, K.

2000-01-01

Fixed energy inverse scattering theory has been used to define central and spin-orbit Schroedinger potentials for the scattering of 5 eV polarized electrons from Xe atoms. The results are typical for a range of such data; including energies above threshold when the potentials become complex. The phase shifts obtained from an analysis of the measured differential cross section and analyzing power has been used as input data. Both semi-classical (WKB) and fully quantal inversion methods have been used to extract central and spin-orbit interactions. The analysis shows that information additional to the set of input phase shifts extracted from this (and similar) data may be needed to ascertain physical potentials

Cross sections of electron excitation out of metastable helium levels with a fast metastable target product produced via charge exchange

International Nuclear Information System (INIS)

Lagus, M.E.; Boffard, J.B.; Anderson, L.W.; Lin, C.C.

1996-01-01

Absolute direct cross sections for electron excitation out of the 2 3 S level and into the 3 3 D, 4 3 D, and 3 3 S levels of the helium atom from threshold to 500 eV and into the 3 3 P level over a more limited energy range have been measured using a fast metastable atomic beam target. We produce the metastable atoms via near-resonant charge exchange between a 1.6-keV He + ion beam and Cs vapor. Because this reaction is highly nonresonant with the ground state of helium, the charge-transfer process yields a primarily metastable beam. We use a thermal detector which we calibrate with ions to measure absolutely the neutral beam flux. The atomic beam is crossed by an electron beam, and we collect the resulting fluorescence at right angles to both the electron and atomic beams. We obtain the cross sections for excitation out of the 2 3 S level into the various excited levels by monitoring the emission out of the excited level of interest. copyright 1996 The American Physical Society

Energy transfers between N_2(A"3Σ) nitrogen metastable molecules and oxygen atoms and molecules

International Nuclear Information System (INIS)

De Souza, Antonio Rogerio

1985-01-01

This research thesis aims at determining reaction coefficients for energy transfers between nitrogen in its metastable status and oxygen atoms and molecules, the variation of these coefficients with respect to temperature (mainly in the 200-400 K range), products formed and more particularly branching rates of O("1S) oxygen and of NO_2. Reaction coefficients are experimentally determined by using the technique of post-discharge in flow. The experimental set-up is described and the study of the best operating conditions is reported. In the next part, the author reports the study of the energy transfer between nitrogen in its metastable status N_2(A) and oxygen molecules. Reaction coefficients are determined for the first three vibrational levels. The author then reports the study of the transfer of N_2(A) molecules on oxygen atoms in their fundamental status. Reactions coefficients and their variations are determined for the three first vibrational levels. The author describes the dissociation method and the method of detection of atomic oxygen. A kinetic model is proposed for the analysis of formed products during a post-discharge in flow, and the branching rate for the formation of O("1S) oxygen between 190 and 365 K is determined. The author finally discusses publications on the role of these reactions in the interpretation of some atmospheric phenomena

Two-photon polarization Fourier spectroscopy of metastable atomic hydrogen

International Nuclear Information System (INIS)

Duncan, A.J.; Beyer, H.-J.; Kleinpoppen, H.; Sheikh, Z.A,; B-Z Univ., Multan

1997-01-01

A novel Fourier-transform spectroscopic method using two-photon polarization to determine the spectral distribution of the two photons emitted in the spontaneous decay of metastable atomic hydrogen is described. The method uses birefringent retardation plates and takes advantage of the subtle interplay between the spectral properties and the entangled polarization properties of the radiation emitted in the decay. Assuming the validity of the theoretical spectral distribution, it is shown that the experimental results agree well with theory. On the other hand, success in solving the inverse problem of determining the spectral distribution from the experimental results is limited by the small number of experimental points. However, making reasonable assumptions it is deduced that the observed spectrum is characterized by a broadband signal of width (0.43 ± 0.06) x 10 16 rad s -1 and centre angular frequency (0.77 ± 0.03) x 10 16 rad s -1 in good agreement with the predictions of 0.489 x 10 16 rad s -1 and 0.775 x 10 16 rad s -1 , respectively, obtained from the theoretical spectral distribution modified to take account of the absorption of the two-photon radiation in air. The values of 1.5 fs for the coherence time and 440 nm for the coherence length for single photons of the two-photon pair which are obtained from the measured bandwidth imply that, in the ideal case, these values are determined by the essentially zero lifetime of the virtual intermediate state of the decay process rather than the long lifetime of the metastable state which, it is suggested, determines the coherence time and coherence length appropriate to certain types of fourth-order interference experiments. (Author)

Relaxation of energetic S(1D) atoms in Xe gas: comparison of ab initio calculations with experimental data.

Science.gov (United States)

Bovino, S; Zhang, P; Kharchenko, V; Dalgarno, A

2011-07-14

In this paper, we report our investigation of the translational energy relaxation of fast S((1)D) atoms in a Xe thermal bath. The interaction potential of Xe-S was constructed using ab initio methods. Total and differential cross sections were then calculated. The latter have been incorporated into the construction of the kernel of the Boltzmann equation describing the energy relaxation process. The solution of the Boltzmann equation was obtained and results were compared with those reported in experiments [G. Nan, and P. L. Houston, J. Chem. Phys. 97, 7865 (1992)]. Good agreement with the measured time-dependent relative velocity of fast S((1)D) atoms was obtained except at long relaxation times. The discrepancy may be due to the error accumulation caused by the use of hard sphere approximation and the Monte Carlo analysis of the experimental data. Our accurate description of the energy relaxation process led to an increase in the number of collisions required to achieve equilibrium by an order of magnitude compared to the number given by the hard-sphere approximation.

One-electron capture and target ionization in He+-neutral-atom collisions

International Nuclear Information System (INIS)

Shevelko, V.P.; Tolstikhina, I.Yu.; Kato, D.; Tawara, H.; Song, M-.Y.; Yoon, J-.S.

2009-12-01

One-electron capture and target-ionization cross sections in collisions of He + ions with neutral atoms: He + + A → He + A + and He + + A → He + + A + + e, A = H, He(1s 2 , 1s2s), Ne, Ar, Kr, Xe, are calculated and compared with available experimental data over the broad energy range E = 0.1 keV/u - 10 MeV/u of He + ions. The role of the metastable states of neutral helium atoms in such collisions, which are of importance in plasma physics applications, is briefly discussed. The recommended cross section data for these processes are presented in a closed analytical form (nine-order polynomials) which can be used for a plasma modeling and diagnostics. (author)

New spectroscopic results in Xe II, Xe III, and Xe IV

OpenAIRE

Reyna Almandos, Jorge Guillermo; Gallardo, Mario; Garavaglia, Mario J.

1982-01-01

New results obtained in spontaneous xenon spectrum employing a conventional pulsed gaseous laser tube as light source, are presented in this work. A total of 626 spectral lines has been ionically assigned as follows: 50 to Xe II spectrum, 103 to Xe III spectrum, arid 222 to Xe IV spectrum. 30 Lines previously assigned to Xe II were reassigned as belonging to Xe III, 94 lines were assigned with some doubts to Xe II-III spectrum and 84 lines to Xe Ill-IV spectrum. Also there were clas...

Disintegration of C60 by Xe ion irradiation

International Nuclear Information System (INIS)

Kalish, R.; Samoiloff, A.; Hoffman, A.; Uzan-Saguy, C.

1993-01-01

The Changes in resistivity of fullerene (C 60 ) films subject to 320 keV Xe ion irradiation are investigated as a function of ion dose. From a comparison of this dependence with similar data on other Xe irradiated C containing insulating materials and with data on C implanted fused quartz, it is concluded that upon ion impact C 60 clusters completely disintegrate. This disintegration releases about 60 C atoms which disperse amongst the remaining intact C 60 spheres giving rise to hopping conductivity between isolated C atoms. 16 refs., 3 figs

Resistivity and morphology of TiSi2 formed on Xe+-implanted polycrystalline silicon

International Nuclear Information System (INIS)

Kuwano, H.; Phillips, J.R.; Mayer, J.W.

1990-01-01

Xe ion irradiation of polycrystalline silicon before Ti deposition is found to affect subsequent silicide formation. Silicide films were prepared by implanting 60, 100, or 240 keV Xe + ions into 500-nm-thick undoped polycrystalline silicon before depositing Ti and annealing in vacuum. Preimplantation altered the subsequent silicide resistivity, x-ray diffraction patterns, and morphology as compared to films prepared on unimplanted polycrystalline Si substrates. We found that minimal TiSi 2 resistivities were achieved at lower temperatures with preimplantation, indicating that the Xe-implanted substrate promotes a lower temperature transition from the metastable C49 phase to the low-resistivity equilibrium C54 phase of TiSi 2 . X-ray diffraction results confirmed the lower temperature formation of the C54 phase with preimplantation. Low-temperature annealing (650 degree C, 30 min) of 6x10 16 cm -2 , 240 keV Xe + -implanted samples yielded low-resistivity (∼22 μΩ cm) silicide films, while simultaneously annealed samples without preimplantation had resistivity five times higher. Lower doses were effective at lower implant energies, with low resistivity achieved after 725 degree C, 30 min annealing for 2x10 15 cm -2 , 60 keV Xe + preimplantation

Metastable and bistable defects in silicon

International Nuclear Information System (INIS)

Mukashev, Bulat N; Abdullin, Kh A; Gorelkinskii, Yurii V

2000-01-01

Existing data on the properties and structure of metastable and bistable defects in silicon are analyzed. Primary radiation-induced defects (vacancies, self-interstitial atoms, and Frenkel pairs), complexes of oxygen, carbon, hydrogen, and other impurity atoms and defects with negative correlation energy are considered. (reviews of topical problems)

Fast production of Bose-Einstein condensates of metastable helium

Science.gov (United States)

Bouton, Q.; Chang, R.; Hoendervanger, A. L.; Nogrette, F.; Aspect, A.; Westbrook, C. I.; Clément, D.

2015-06-01

We report on the Bose-Einstein condensation of metastable 4He atoms using a hybrid approach, consisting of a magnetic quadrupole and an optical dipole trap. In our setup we cross the phase transition with 2 ×106 atoms, and we obtain pure condensates of 5 ×105 atoms in the optical trap. This approach to cooling 4He provides enhanced cycle stability, large optical access to the atoms and results in the production of a condensate every 6 s—a factor 2 faster than the state of the art. This speed-up will significantly reduce the data acquisition time needed for the measurement of many particle correlations, made possible by the ability of metastable helium atoms to be detected individually.

Studies on production of metastable core-excited atoms by laser-produced x-rays. Final report, 1 October 1984-30 September 1985

International Nuclear Information System (INIS)

Harris, S.E.; Young, J.F.

1986-04-01

The overall objective of the work on this program was to study methods for production of core-excited metastable atoms by laser-generated x-rays. We are interested in the spectroscopy of these levels, their autoionizing and radiative rates, and their metastability in the presence of hot electrons and ions. The concept of using x-rays emitted from a laser-produced plasma to excite large densities of energetic excited levels in atoms and ions has been thoroughly experimentally investigated using modest, 100 mJ, plasma-producing lasers. One of the objectives of this work was to verify that these techniques could be scaled up to higher energies, such as 20 J. Thus a major effort this year has been devoted to the design and construction of the high energy (20 J) 1064 nm plasma-forming laser system and the tunable probe/transfer laser

Trampoline motions in Xe-graphite(0 0 0 1) surface scattering

Science.gov (United States)

Watanabe, Yoshimasa; Yamaguchi, Hiroki; Hashinokuchi, Michihiro; Sawabe, Kyoichi; Maruyama, Shigeo; Matsumoto, Yoichiro; Shobatake, Kosuke

2005-09-01

We have investigated Xe scattering from the graphite(0 0 0 1) surface at hyperthermal incident energies using a molecular beam-surface scattering technique and molecular dynamics simulations. For all incident conditions, the incident Xe atom conserves the momentum parallel to the surface and loses approximately 80% of the normal incident energy. The weak interlayer potential of graphite disperses the deformation over the wide range of a graphene sheet. The dynamic corrugation induced by the collision is smooth even at hyperthermal incident energy; the graphene sheet moves like a trampoline net and the Xe atom like a trampoliner.

Double beta decay searches of 134Xe, 126Xe and 124Xe with large scale Xe detectors

International Nuclear Information System (INIS)

Barros, N; Thurn, J; Zuber, K

2014-01-01

The sensitivity for double beta decay studies of 134 Xe and 124 Xe is investigated assuming a potential large scale Xe experiment developed for dark matter searches depleted in 136 Xe. The opportunity for an observation of the 2νββ - decay of 134 Xe is explored for various scenarios. A positive observation should be possible for all calculated nuclear matrix elements. The detection of 2ν ECEC of 124 Xe can be probed in all scenarios covering the theoretical predicted half-life uncertainties and a potential search for 126 Xe is discussed. The sensitivity to β + EC decay of 124 Xe is discussed and a positive observation might be possible, while β + β + decay still remains unobservable. The performed studies take into account solar pp–neutrino interactions, 85 Kr beta decay and remaining 136 Xe double beta decay as background components in the depleted detector. (paper)

Plasma effects on the metastable H0(2s) atom

International Nuclear Information System (INIS)

Benage, J.F. Jr.

1986-01-01

Atomic radiative processes that occur in plasmas have long been of interest of plasma physicists. The process investigated here is atomic dipole transitions, specifically transitions from the metastable 2s to the 2p in hydrogen, which are induced by processes that occur in the plasma. An experiment was done to measure the rate of transitions from 2s to 2p in hydrogen. This experiment was divided into two sections. The first was to measure the transition rate in a near equilibrium plasma. The second section measured the transition rate when RF oscillations were imposed on the plasma. Results of the first part show that microscopic fluctuating electric fields produced by the motions of the charged particles induce transitions from 2s to 2p in hydrogen. The magnitude of this effect is compared to predicted transition rates due to collisions with electrons and ions and to rates predicted for an equilibrium plasma. In the second part, the plasma was shown to act as a filter, preventing transitions from being caused by the RF unless the RF was in the range where plasma waves could be launched. The interpretation given for this effect is that, when the oscillations are inducing transitions, it is because plasma waves are being launched in the plasma and it is these waves that are inducing the transitions

Laser absorption spectroscopy for measurement of He metastable atoms of a microhollow cathode plasma

Science.gov (United States)

Ueno, Keisuke; Kamebuchi, Kenta; Kakutani, Jiro; Matsuoka, Leo; Namba, Shinichi; Fujii, Keisuke; Shikama, Taiichi; Hasuo, Masahiro

2018-01-01

We generated a 0.3-mm-diameter DC, hollow-cathode helium discharge in a gas pressure range of 10-80 kPa. In discharge plasmas, we measured position-dependent laser absorption spectra for helium 23S1-23P0 transition with a spatial resolution of 55 µm. From the results of the analysis of the measured spectra using Voigt functions and including both the Doppler and collision broadening, we produced two-dimensional maps of the metastable 23S1 atomic densities and gas temperatures of the plasmas. We found that, at all pressures, the gas temperatures were approximately uniform in space with values in the range of 400-1500 K and the 23S1 atomic densities were ˜1019 m-3. We also found that the two-dimensional density distribution profiles became ring-shaped at high gas pressures, which is qualitatively consistent with the two-dimensional fluid simulation results.

Present status of the {sup 129}Xe comagnetometer development for neutron EDM measurement

Energy Technology Data Exchange (ETDEWEB)

Mihara, M., E-mail: mihara@vg.phys.sci.osaka-u.ac.jp [Osaka University, Department of Physics (Japan); Masuda, Y. [Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK) (Japan); Matsuta, K. [Osaka University, Department of Physics (Japan); Kawasaki, S.; Watanabe, Y. [Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK) (Japan); Hatanaka, K.; Matsumiya, R. [Osaka University, Research Center for Nuclear Physics (RCNP) (Japan)

2016-12-15

A {sup 129}Xe comagnetometer designed for the measurement of neutron electric dipole moment (nEDM) as precisely as 1 × 10{sup −27}e cm is presented. Highly nuclear spin polarized {sup 129}Xe are introduced into an EDM cell where the {sup 129}Xe spin precession is detected by means of the two-photon transition. The geometric phase effect (GPE) which generates the false nEDM was quantitatively discussed and the systematic error of nEDM from the GPE was estimated considering the buffer-gas suppression due to Xe atomic collisions. Research and development are in progress to construct the {sup 129}Xe comagnetometer with a field sensitivity of 0.3 fT. At present, about 70 % nuclear spin polarized {sup 129}Xe atoms have been obtained in a spin exchange opitial pumping cell, that are in the process of being transferred into the EDM cell via a cold trap.

Formation of (Xe2H)* centers in solid Xe via recombination: nonstationary luminescence and 'internal electron emission'

International Nuclear Information System (INIS)

Savchenko, E.V.; Khyzhniy, I.V.; Uyutov, S.A.; Gumenchuk, G.B.; Ponomarev, A.N.; Bondybey, V.E.; Beyer, M.K.

2010-01-01

The formation of excimers (Xe 2 H) * in solid Xe doped with molecular hydrogen under electron beam is studied using the original two-stage technique of nonstationary (NS) cathodoluminescence (CL) in combination with the current activation spectroscopy method - thermally stimulated exoelectron emission (TSEE). Charged species were generated using a high-density electron beam. The species produced were then probed with a low density beam on gradual sample heating. The near UV emission of the (Xe 2 H) * was used to monitor the neutralization process. It is found that the temperature behavior of the NS CL band of (Xe 2 H) * clearly correlates with the yield of TSEE measured after identical pre-irradiation of the sample. The fingerprints of the thermally stimulated detrapping of electrons - 'internal electron emission' in the spectrum of NS CL point to the essential role of neutralization reaction in the stability of the proton solvated by rare-gas atoms.

Ionization energies of Xe2+ and Xe3+

International Nuclear Information System (INIS)

Dutil, R.; Marmet, P.

1980-01-01

New electron impact measurements show that the previously accepted energies of ionization of Xe 2+ and Xe 3+ from xenon are erroneous. These energies are determined 33.11 +- 0.04 eV for Xe 2+ and 64.35 +- 0.10 eV for Xe 3+ . New structures are seen by electron impact just above the Xe 2+ threshold. New information is also given on the ionization energies of Xe 4+ and Xe 5+ . (orig.)

A comparison between the irradiation damage response of spinel and zirconia due to Xe ion bombardment

International Nuclear Information System (INIS)

Sickafus, K.E.; Wetteland, C.J.; Baker, N.P.; Yu Ning; Devanathan, R.; Nastasi, M.; Bordes, N.

1998-01-01

The mechanical properties of Xe-implanted spinel and cubic zirconia surfaces, as determined by nano-indentation measurements, are distinct and the differences can be related to their microstructures. Upon Xe 2+ ion irradiation to high dose at cryogenic temperature (120 K), the Young's modulus of irradiated spinel falls dramatically until the modulus is only about 3/4 the un-irradiated value. The maximum modulus occurs concurrent with the formation of a metastable crystalline phase of spinel. The subsequent elastic softening at higher Xe 2+ doses is an indication of the onset of amorphization of the spinel. Xe-implanted zirconia surfaces behave differently, in all cases showing almost no change in elastic modulus with increasing Xe 2+ ion dose. This is consistent with microstructural observations of Xe-implanted zirconia crystals which, unlike spinel, show no change in crystal structure with increasing ion dose. The hardness of both spinel and zirconia increases slightly for low Xe 2+ ion doses. At higher doses, zirconia shows little change in hardness, while the hardness of the implanted spinel falls by more than a factor of two. The initial increase in hardness of both spinel and zirconia is consistent with point defect accumulation and the precipitation of small interstitial clusters, while the drop in hardness of spinel at high Xe 2+ ion doses is due to the formation of an amorphous phase. (orig.)

Kinetics of the processes, plasma parameters, and output characteristics of a UV emitter operating on XeI molecules and iodine molecules and atoms

Energy Technology Data Exchange (ETDEWEB)

Shuaibov, A. K.; Grabovaya, I. A.; Minya, A. I.; Homoki, Z. T. [Uzhgorod National University (Ukraine); Kalyuzhnaya, A. G.; Shchedrin, A. I. [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)

2011-03-15

A kinetic model of the processes occurring in the plasma of a high-power low-pressure gas-discharge lamp is presented, and the output characteristics of the lamp are described. The lamp is excited by a longitudinal glow discharge and emits the I{sub 2}(D Prime -A Prime ) 342-nm and XeI(B-X) 253-nm bands and the 206.2-nm spectral line of atomic iodine. When the emitter operates in a sealed-off mode on the p(He): p(Xe): p(I{sub 2}) = 400: 120: (100-200) Pa mixture, the fractions of the UV radiation power of iodine atoms, exciplex molecules of xenon iodide, and iodine molecules comprise 55, 10, and 35%, respectively. At the optimal partial pressure, the maximum total radiation power of the lamp reaches 37 W, the energy efficiency being about 15%.

Radiative and nonradiative lifetimes in excited states of Ar, Kr and Xe atoms in Ne matrix

International Nuclear Information System (INIS)

Hahn, U.; Schwentner, N.

1979-10-01

Synchrotron radiation with its intense continuum and its excellent time structure has been exploited for time resolved luminescence spectroscopy in the solid state. By selective excitation of n = 1, n' = 1 and n = 2 exciton states of Xe, Kr and Ar atoms in Ne matrix we were able to identify the emitting states involved. Lifetimes within the cascade of radiative and radiationless relaxation between excited states as well as the radiative lifetimes for transitions to the ground state have been derived from the decay curves. Energy positions and radiative lifetimes of the emitting states correspond quite well with those of the free atoms. Radiative and radiationless relaxation processes take place within the manifold of excited states of the guest atoms. The rate constants for radiationless decay confirm an energy gap law. The order of the radiationless processes reaches in some cases extremely high values. Selection rules for spin and angular momentum are essential to understand the observed radiationless transition rates. (orig.)

Extension of equilibrium formation criteria to metastable microalloys

International Nuclear Information System (INIS)

Kaufmann, E.N.; Vianden, R.; Chelikowsky, J.R.; Phillips, J.C.

1977-01-01

Metastable microalloys of 25 metallic elements with beryllium have been prepared by ion implantation. The injected atoms have been found to occupy one of three sites available in the solvent lattice. A modified Laudau-Ginsburg expansion using bulk alloy variables proposed by Miedema is completely successful in predicting the observed metastable-site preferences and indicates a broader applicability of these variables than was heretofore anticipated

Primordial Terrestrial Xe from the Viewpoint of CFF-Xe

Science.gov (United States)

Meshik, A. P.; Shukolyukov, Yu. A.; Jessberger, E. K.

1995-09-01

We have already reported [7, 23] on the non-linear isotope mass-fractionation of fission Xe by migration of the precursors I, Te, Sn, and Sb and simultaneous fission of heavy nuclei. Xe with anomalous isotopic pattern was found in a number of meteorites and terrestrial materials and was named CFF-Xe (Chemically Fractionated Fission Xe). It is characterized by an up eightfold ^132Xe and ^131Xe excesses coupled with smaller ^134Xe and ^129Xe excesses. The present work is aimed to estimate the role of CFF-Xe in the terrestrial lithosphere and specifically deals with the problem of the isotopic composition of primordial terrestrial Xe. Due to variations of the migration conditions the isotopic structure of CFF-Xe is not well established and is even not reproducible in the same rock [2]. Nevertheless, we have tried to estimate the composition of CFF-Xe by investigating all available isotopic data of Xe of presumable mantle origin. This is Xe in MORB [29, 1, 12] and ocean island glasses [1, 28], in diamonds [17], in volcanic rocks [29, 8, 9, 21], in volcanic glasses from pillow basalts [16, 6], continental igneous rocks [1, 24, 10, 22], carbonatites and granitoids [1] as well as Xe in natural gases [3, 24, 11, 4, 15]. All data are plotted Fig. 1 where we also suggest end members of the observed scattering. Optimized slopes of CFF-lines are shown as well as the position of the initial points which we regard as primordial terrestrial Xe (Xe0). The isotopic composition of CFF-Xe and Xe0 are given in Tab. 1. The abundances of ^124Xe and ^126Xe in mantle derived samples are very uncertain, but since ^128Xe/^130Xe in Xea and Xe0 is very similar we propose the same ^124Xe/^130Xe and ^126Xe/^130Xe ratios for both Xea and Xe0. If so, AVCC-Xe is simply Xe0 with an admixture of L-Xe, and atmospheric xenon Xea consists of Xe0, CFF-Xe and a small amount of fission Xe (92.5%Xe0 + 5.3%CFF-Xe + 2.2%XeF). Thus, a number of old problems in xenology are removed. The hypothetic components U-Xe

Discharge characteristics of He-Ne-Xe gas mixture with varying Xe contents and at varying sustain electrode gap lengths in the plasma display panel

International Nuclear Information System (INIS)

Kwon, Ohyung; Whang, Ki-Woong; Bae, Hyun Sook

2009-01-01

The discharge characteristics of He-Ne-Xe gas mixture in the plasma display panel were investigated using a two-dimensional numerical simulation to understand the effects of adding He and varying the Xe contents in the gas mixture, and also varying sustain electrode gap. With 5% Xe content and 60 μm sustain electrode gap, decreased ionization led to the improvement of the vacuum ultraviolet (vuv) efficacy at increasing He mixing ratios. However, at 20% Xe content and 60 μm sustain electrode gap, increased electron heating improved the vuv efficacy until the He mixing ratio reached 0.7, but the efficacy decreased beyond the ratio of 0.7 due to the increased ionization of Xe atoms. At 5% Xe content and 200 μm sustain electrode gap, the vuv efficacy increased as a result of increased electron heating at the gap space at increasing He mixing ratios.

Role of metastable atoms in argon-diluted silane Rf plasmas

International Nuclear Information System (INIS)

Sansonnens, L.; Howling, A.A.; Hollenstein, C.; Dorier, J.L.; Kroll, U.

1994-01-01

The evolution of the argon metastable density has been studied by absorption spectroscopy in power-modulated plasmas of argon and a mixture of 4% silane in argon. A small concentration of silane suppresses the argon metastable density by molecular quenching. This molecular quenching adds to the electronic collisional dissociation to increase the silane dissociation rate as compared with pure silane plasmas. Using time-resolved emission spectroscopy, the role of metastables in excitation to the argon 2P 2 state has been determined in comparison with production from the ground state. In silane plasmas, emission from SiH* is due essentially to electron impact dissociation of silane, whereas in 4% silane-in-argon plasmas, emission from SiH* seems to be due to electron impact excitation of the SiH ground state. These studies demonstrate that argon is not simply a buffer gas but has an influence on the dissociation rate in the plasma-assisted deposition of amorphous silicon using argon-diluted silane plasmas. (author) 7 figs., 30 refs

Anomalous evolution of Ar metastable density with electron density in high density Ar discharge

International Nuclear Information System (INIS)

Park, Min; Chang, Hong-Young; You, Shin-Jae; Kim, Jung-Hyung; Shin, Yong-Hyeon

2011-01-01

Recently, an anomalous evolution of argon metastable density with plasma discharge power (electron density) was reported [A. M. Daltrini, S. A. Moshkalev, T. J. Morgan, R. B. Piejak, and W. G. Graham, Appl. Phys. Lett. 92, 061504 (2008)]. Although the importance of the metastable atom and its density has been reported in a lot of literature, however, a basic physics behind the anomalous evolution of metastable density has not been clearly understood yet. In this study, we investigated a simple global model to elucidate the underlying physics of the anomalous evolution of argon metastable density with the electron density. On the basis of the proposed simple model, we reproduced the anomalous evolution of the metastable density and disclosed the detailed physics for the anomalous result. Drastic changes of dominant mechanisms for the population and depopulation processes of Ar metastable atoms with electron density, which take place even in relatively low electron density regime, is the clue to understand the result.

Field Induced Magnetic Moments in a Metastable Iron-Mercury Alloy

DEFF Research Database (Denmark)

Pedersen, M.S.; Mørup, Steen; Linderoth, Søren

1996-01-01

The magnetic properties of a metastable iron-mercury alloy have been investigated in the temperature range from 5 to 200 K by Mossbauer spectroscopy and magnetization measurements. At low temperature the magnetic moment per iron atom is larger than af alpha-Fe. The effective spontaneous magnetic ....... It was found that the field-induced increase of the magnetic moment in the metastable iron-mecury alloy was about 0.06 Bohr magnetons per iron atom in the temperature range from 5 to 200 K for a field change from 6 to 12 T....

Production of H(2s) fast metastable atoms (0.25-3 keV) on a Cs target. Detection of the α Lyman radiation induced by Stark effect: polarisation. Destruction of H(2s) atoms on an IH target

International Nuclear Information System (INIS)

Valance, Antoine.

1974-01-01

The production, detection and destruction of the 2S1/2 metastable state of the hydrogen atom were studied. The quasi-resonant charge exchange processes between fast protons and cesium target, in the total cross sections for production of metastable H(2s) atoms and radiative H(2p) atoms showed structures hitherto unobserved. The theoretical study is based on calculation of the adiabatic molecular potential terms of the ionic quasi-molecule (CsH) + , taking a Helmann type pseudopotential to describe the electron with respect to the core of the cesium ion. The probabilities of transition towards the output channels are calculated using a stationary state perturbation method. From the data obtained the interferece phenomena of excited quasi-molecular states can be interpreted coherently in slow collision. The probability of transition along the inelastic output channels displays characteristics of a harmonic oscillatory function inversely proportional to the speed of approach of the particles. The frequency of these oscillations depends very slightly on the impact parameter. The theory proposed involves three Σ states. During detection of the metastable ions the Lyman-α radiation induced in the de-excitation electric field by Stark effect present anisotropic features. The degree of polarization measured as a function of the field strength oscillates around a slow decay toward a limit-1 at strong electric field. A theory not accounting for the hyperfine structure of states mixed by Stark effect showed a double oscillatory structure containing the two frequencies correlated to the 2P1/2 and 2P3/2 states from the 2S1/2 state. Finally the results on the electron detachment reaction between fast metastable atoms and hydroiodic acid target have contributed towards research on polarized proton sources [fr

Laser Spectroscopy of Antiprotonic Helium Atoms

CERN Multimedia

2002-01-01

%PS205 %title\\\\ \\\\Following the discovery of metastable antiprotonic helium atoms ($\\overline{p}He^{+} $) at KEK in 1991, systematic studies of their properties were made at LEAR from 1991 to 1996. In the first two years the lifetime of $\\overline{p}He^{+}$ in liquid and gaseous helium at various temperatures and pressures was measured and the effect of foreign gases on the lifetime of these atoms was investigated. Effects were also discovered which gave the antiproton a 14\\% longer lifetime in $^4$He than in $^3$He, and resulted in important differences in the shape of the annihilation time spectra in the two isotopes.\\\\ \\\\Since 1993 laser spectroscopy of the metastable $\\overline{p}He^{+}$ atoms became the main focus of PS205. Transitions were stimulated between metastable and non-metastable states of the $\\overline{p}He^{+}$ atom by firing a pulsed dye laser beam into the helium target every time an identified metastable atom was present (Figure 1). If the laser frequency matched the transition energy, the...

Spin-polarized 3He nuclear targets and metastable 4He atoms by optical pumping with a tunable, Nd:YAP laser

International Nuclear Information System (INIS)

Bohler, C.L.; Schearer, L.D.; Leduc, M.; Nacher, P.J.; Zachorowski, L.; Milner, R.G.; McKeown, R.D.; Woodward, C.E.

1988-01-01

Several Nd:YAP lasers were constructed which could be broadly tuned in the 1083-nm region which includes the helium 2 3 S-2 3 P transition, using a Lyot filter and thin, uncoated etalons within the laser cavity. 1 W of power could be extracted at 1083 nm through a 1% transmitting output coupler. This laser beam was used to optically pump metastable 4 He and 3 He 2 3 S helium atoms in a weak discharge cell, spin polarizing the metastable ensemble. In a 3 He cell the polarization is transferred to the nuclear spin system. A 3 He target cell at 0.3 Torr was polarized to 52% in a few minutes. We describe the application of this system to the design of polarized targets for experiments in nuclear physics

Ionization of small molecules by state-selected neon (3P0, 3P2) metastable atoms in the 0.06

NARCIS (Netherlands)

Berg, van den F.T.M.; Schonenberg, J.H.M.; Beijerinck, H.C.W.

1987-01-01

The velocity dependence and absolute values of the total ionisation cross section for the molecules H2, N2, O2, NO, CO, N2O, CO2, and CH4 by metastable Ne* (3P0) and Ne* (3P2) atoms at collision energies ranging from 0.06 to 6.0 eV have been measured in a crossed beam experiment. State selection of

Monitoring of atomic metastable state lifetimes by the laser-enhanced ionization technique--A new method for probing local stoichiometric combustive conditions

International Nuclear Information System (INIS)

Ljungberg, Peter; Malmsten, Yvonne; Axner, Ove

1995-01-01

The lifetimes of atomic metastable states in an acetylene/air flame have been investigated using the laser-enhanced ionization technique. The lifetimes were found to be several orders of magnitude less than the natural ones, which clearly shows that they are fully determined by the surrounding environment. The lifetime of a specific state has been investigated as a function of flame conditions. It was found that the lifetime is strongly dependent on the local flame composition, with a distinct maximum for stoichiometric conditions. For fuel-lean local conditions, the excess of O2 acts as an effective quencher of the metastable state, while for fuel-rich conditions the quenching is dominated by unburned fuel components. An acetylene/air flame has been probed both as a function of height in the flame, as well as a function of fuel/air composition fed to the burner. The experiments show clearly for which heights and fuel/air compositions that lean, stoichiometric or rich conditions prevail. This makes a monitoring of metastable state lifetimes a useful technique for combustion analysis

Probing the porosity of cocrystallized MCM-49/ZSM-35 zeolites by hyperpolarized 129Xe NMR.

Science.gov (United States)

Liu, Yong; Zhang, Weiping; Xie, Sujuan; Xu, Longya; Han, Xiuwen; Bao, Xinhe

2008-01-31

One- and two-dimensional 129Xe NMR spectroscopy has been employed to study the porosity of cocrystallized MCM-49/ZSM-35 zeolites under the continuous flow of hyperpolarized xenon gas. It is found by variable-temperature experiments that Xe atoms can be adsorbed in different domains of MCM-49/ZSM-35 cocrystallized zeolites and the mechanically mixed counterparts. The exchange of Xe atoms in different types of pores is very fast at ambient temperatures. Even at very low temperature two-dimensional exchange spectra (EXSY) show that Xe atoms still undergo much faster exchange between MCM-49 and ZSM-35 analogues in the cocrystallized zeolites than in the mechanical mixture. This demonstrates that the MCM-49 and ZSM-35 analogues in cocrystallized zeolites may be stacked much closer than in the physical mixture, and some parts of intergrowth may be formed due to the partially similar basic structure of MCM-49 and ZSM-35.

Trapping cold ground state argon atoms.

Science.gov (United States)

Edmunds, P D; Barker, P F

2014-10-31

We trap cold, ground state argon atoms in a deep optical dipole trap produced by a buildup cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of cotrapped metastable argon atoms and determine an elastic cross section. Using a type of parametric loss spectroscopy we also determine the polarizability of the metastable 4s[3/2](2) state to be (7.3±1.1)×10(-39)  C m(2)/V. Finally, Penning and associative losses of metastable atoms in the absence of light assisted collisions, are determined to be (3.3±0.8)×10(-10)  cm(3) s(-1).

He 3 -Xe 129 Comagnetometery using Rb 87 Detection and Decoupling

Science.gov (United States)

Limes, M. E.; Sheng, D.; Romalis, M. V.

2018-01-01

We describe a He 3 -Xe 129 comagnetometer using Rb 87 atoms for noble-gas spin polarization and detection. We use a train of Rb 87 π pulses and σ+/σ- optical pumping to realize a finite-field Rb magnetometer with suppression of spin-exchange relaxation. We suppress frequency shifts from polarized Rb by measuring the He 3 and Xe 129 spin precession frequencies in the dark, while applying π pulses along two directions to depolarize Rb atoms. The plane of the π pulses is rotated to suppress the Bloch-Siegert shifts for the nuclear spins. We measure the ratio of He 3 to Xe 129 spin precession frequencies with sufficient absolute accuracy to resolve Earth's rotation without changing the orientation of the comagnetometer. A frequency resolution of 7 nHz is achieved after integration for 8 h without evidence of significant drift.

Search for a permanent Xe-electric dipole moment

Energy Technology Data Exchange (ETDEWEB)

Zimmer, Stefan [Institut fuer Physik, Universitaet Mainz (Germany); Collaboration: MIXed-Collaboration

2016-07-01

A permanent electric dipole moment (EDM) of the isotope {sup 129}Xe would imply a breakdown of both parity P and time-reversal symmetry T and, through the CPT theorem, a breakdown in CP, the combined symmetries of charge conjugation C and parity P. Our goal is to improve the present experimental limit (d{sub Xe}<3.10{sup -27} ecm) by about three orders of magnitude. The most precise EDM limit on diamagnetic atoms was measured on {sup 199}Hg (d{sub Hg}<3.1.10{sup -29} ecm). To get more stringent limits, we perform a {sup 3}He/{sup 129}Xe clock comparison experiment with the detection of free spin precession of gaseous, nuclear polarized {sup 3}He or {sup 129}Xe samples with a SQUID as magnetic flux detector. The precession of co-located {sup 3}He/{sup 129}Xe nuclear spins are used as an ultra-sensitive probe for non-magnetic spin interactions of type δν∝ d{sub Xe}.E. With our experimental setup at the research center Juelich we are able to observe spin coherence times T{sub 2}{sup *} of several hours for both species. We report on first experimental results achieved within the MIXed-collaboration.

124Xe(n,γ)125Xe and 124Xe(n,2n)123Xe measurements for National Ignition Facility

Science.gov (United States)

Bhike, Megha; Ludin, Nurin; Tornow, Werner

2015-05-01

The cross section for the 124Xe(n,γ)125Xe reaction has been measured for the first time for neutron energies above 100 keV. In addition, the 124Xe(n,2n)123Xe reaction has been studied between threshold and 14.8 MeV. The results of these measurements provide sensitive diagnostic tools for investigating properties of the inertial confinement fusion plasma in Deuterium-Tritium (DT) capsules at the National Ignition Facility (NIF) located at Lawrence Livermore National Laboratory.

Observation of elastic scattering effects on photoelectron angular distributions in free Xe clusters

International Nuclear Information System (INIS)

Oehrwall, G; Tchaplyguine, M; Gisselbrecht, M; Lundwall, M; Feifel, R; Rander, T; Schulz, J; Marinho, R R T; Lindgren, A; Sorensen, S L; Svensson, S; Bjoerneholm, O

2003-01-01

We report an observation of substantial deviations in the photoelectron angular distribution for photoionization of atoms in free Xe clusters compared to the case of photoionization of free atoms. The cross section, however, seems not to vary between the cluster and free atoms. This observation was made in the vicinity of the Xe 4d Cooper minimum, where the atomic angular distribution is known to vary dramatically. The angular distribution of electrons emitted from atoms in the clusters is more isotropic than that of free atoms over the entire kinetic energy range studied. Furthermore, the angular distribution is more isotropic for atoms in the interior of the clusters than for atoms at the surface. We attribute this deviation to elastic scattering of the outgoing photoelectrons. We have investigated two average cluster sizes, ≥ 4000 and 1000 and found no significant differences between these two cases

124Xe(n,γ125Xe and 124Xe(n,2n123Xe measurements for National Ignition Facility

Directory of Open Access Journals (Sweden)

Bhike Megha

2015-01-01

Full Text Available The cross section for the 124Xe(n,γ125Xe reaction has been measured for the first time for neutron energies above 100 keV. In addition, the 124Xe(n,2n123Xe reaction has been studied between threshold and 14.8 MeV. The results of these measurements provide sensitive diagnostic tools for investigating properties of the inertial confinement fusion plasma in Deuterium-Tritium (DT capsules at the National Ignition Facility (NIF located at Lawrence Livermore National Laboratory.

129 Xe-NMR of carbon black filled elastomers

International Nuclear Information System (INIS)

Sperling-Ischinsky, K.; Veeman, W.S.

1999-01-01

It is shown that 129 Xe-NMR is a powerful tool to investigate carbon black and carbon black filled elastomers. For the carbon black material itself the 129 Xe chemical shift of xenon adsorbed at the surface of carbon black aggregates yields information about the relative average pore size of the carbon black aggregates. The experimental 129 Xe-NMR results of carbon black filled ethylene-propylene-diene (EPDM) can be explained when it is assumed that the xenon atoms in the bound EPDM fraction exchange rapidly on the NMR time scale between a state where they are adsorbed on the carbon black surface and a state in which they are absorbed in the EPDM layer. This would imply that the carbon black aggregates are not completely covered with EPDM chains. (author)

Magneto-optical trap for metastable helium at 389 nm

NARCIS (Netherlands)

Koelemeij, J.C.J.; Stas, R.J.W.; Hogervorst, W.; Vassen, W.

2003-01-01

We have constructed a magneto-optical trap (MOT) for metastable triplet helium atoms utilizing the 2 S-3(1)-->3 P-3(2) line at 389 nm as the trapping and cooling transition. The far-red-detuned MOT (detuning Delta=-41 MHz) typically contains few times 10(7) atoms at a relatively high (similar

Long lived quantum memory with nuclear atomic spins

International Nuclear Information System (INIS)

Sinatra, A.; Reinaudi, G.; Dantan, A.; Giacobino, E.; Pinard, M.

2005-01-01

We propose store non-classical states of light into the macroscopic collective nuclear spin (10 18 atoms) of a 3 He vapor, using metastability exchange collisions. We show that these collisions currently used to transfer orientation from the metastable state 2 3 S 1 to the ground state state of 3 He, may conserve quantum correlations and give a possible experimental scheme to perfectly map a squeezed vacuum field state onto a nuclear spin state, which should allow for extremely long storage times (hours). In addition to the apparent interest for quantum information, the scheme offers the intriguing possibility to create a long-lived non classical state for spins. During a metastability exchange collision an atom in the ground state state and an atom in the metastable triplet state 2 3 S exchange their electronic spin variables. The ground state atom is then brought into the metastable state and vice-versa. A laser transition is accessible from the metastable state so that the metastable atoms are coupled with light. This, together with metastability exchange collisions, provides an effective coupling between ground state atoms and light. In our scheme, a coherent field and a squeezed vacuum field excite a Raman transition between Zeeman sublevels of the metastable state, after the system is prepared in the fully polarized state by preliminary optical pumping. According to the intensity of the coherent field, which acts as a control parameter, the squeezing of the field can be selectively transferred either to metastable or to ground state atoms. Once it is encoded in the purely nuclear spin of the ground state of 3 He, which is 20 eV apart from the nearest excited state and interacts very little with the environment, the quantum state can survive for times as long as several hours. By lighting up only the coherent field in the same configuration as for the 'writing' phase, the nuclear spin memory can be 'read' after a long delay, the squeezing being transferred

Flow measurements in biological systems using Xe-127 and Xe-133

International Nuclear Information System (INIS)

Tripathi, R.R.

1981-01-01

Xe-133 and Xe-127 are widely used for quantitative evaluation of ventilation in human subjects. Owing to differences in scattering in the biological system as well as differences in the detector response to photons of selected energies, clinical Xe-133 images are much more distorted than the corresponding Xe-127 images. This thesis concerns itself with the evaluation of Xe-133 and Xe-127 as potential tracers for pulmonary function studies. Through the simulation of clinical images it is shown that such smaller abnormalities are able to be detected with Xe-127 than with Xe-133. It is also found that even for poorly ventilated regions, the measured lesion size in the simulated image is comparable to the known lesion size when studied with Xe-127. With Xe-133, however, the measured size of the lesion is smaller than its known size. By fitting the washout portion of the clinical data to a linear sum of two exponentials, a weighted average clearance constant for the tracer - which relates to the reciprocal of the mean flow through the system - can be calculated and used as an index for comparison of the two Xenon isotopes. When an appropriate model is used for data interpretation, more accurate clinical information can be derived from the Xe-127 data. Unlike Xe-133, ventilation study with Xe-127 can be performed immediately after the perfusion study with Tc-99m. Lower radiation dose and longer shelf-life of Xe-127 are added advantages over Xe-133. Various compartmental and non-compartmental models are examined and appropriate technique(s) for clinical data interpretation is(are) recommended

Enhancement of molecular NMR signal induced by polarization transfer from laser-polarized 129Xe

International Nuclear Information System (INIS)

Sun Xianping

2001-01-01

There is a large non-equilibrium nuclear polarization and a longer relaxation time in the laser-polarized 129 Xe produced by means of optical pumping and spin exchange. The characteristics of the laser-polarized 129 Xe permit the transfer of the polarization to enhance the atomic nuclear spin in liquid, solid and surface of solid molecules. Therefore, the sensitivity in nuclear magnetic resonance measurements for the molecules is enhanced and applications in the investigations of materials and surface sciences are expanded. The progress in the investigations of materials and surface sciences are expanded. The progress in the investigations of the polarization transfer between laser-polarized 129 Xe and the atomic nuclei in the molecules, the relative physics and the measurement of some parameters are introduced

Stable Chloro- and Bromoxenate Cage Anions; [X3(XeO3)3]3- and [X4(XeO3)4]4- (X = Cl or Br).

Science.gov (United States)

Goettel, James T; Haensch, Veit G; Schrobilgen, Gary J

2017-06-28

The number of isolable compounds which contain different noble-gas-element bonds is limited for xenon and even more so for krypton. Examples of Xe-Cl bonds are rare, and prior to this work, no Xe-Br bonded compound had been isolated in macroscopic quantities. The syntheses, isolation, and characterization of the first compounds to contain Xe-Br bonds and their chlorine analogues are described in the present work. The reactions of XeO 3 with [N(CH 3 ) 4 ]Br and [N(C 2 H 5 ) 4 ]Br have provided two bromoxenate salts, [N(C 2 H 5 ) 4 ] 3 [Br 3 (XeO 3 ) 3 ] and [N(CH 3 ) 4 ] 4 [Br 4 (XeO 3 ) 4 ], in which the cage anions have Xe-Br bond lengths that range from 3.0838(3) to 3.3181(8) Å. The isostructural chloroxenate anions (Xe-Cl bond lengths, 2.9316(2) to 3.101(4) Å) were synthesized by analogy with their bromine analogues. The bromo- and chloroxenate salts are stable in the atmosphere at room temperature and were characterized in the solid state by Raman spectroscopy and low-temperature single-crystal X-ray diffraction, and in the gas phase by quantum-chemical calculations. They are the only known examples of cage anions that contain a noble-gas element. The Xe-Br and Xe-Cl bonds are very weakly covalent and can be viewed as σ-hole interactions, similar to those encountered in halogen bonding. However, the halogen atoms in these cases are valence electron lone pair donors, and the σ* Xe-O orbitals are lone pair acceptors.

Saturated multikilovolt x-ray amplification with Xe clusters: single-pulse observation of Xe(L) spectral hole burning

International Nuclear Information System (INIS)

Borisov, Alex B; Davis, Jack; Song, Xiangyang; Koshman, Yevgeniya; Dai Yang; Boyer, Keith; Rhodes, Charles K

2003-01-01

Single-pulse measurements of spectral hole burning of Xe(L) 3d → 2p hollow atom transition arrays observed from a self-trapped plasma channel provide new information on the dynamics of saturated amplification in the λ ∼ 2.8-2.9 A region. The spectral hole burning on transitions in the Xe 34+ and Xe 35+ arrays reaches full suppression of the spontaneous emission and presents a corresponding width Δ h-bar ω x ∼ = 60 eV, a value adequate for efficient amplification of multikilovolt x-ray pulses down to a limiting length τ x ∼ 30 as. The depth of the suppression at 2.86 A indicates that the gain-to-loss ratio is ≥10. An independent determination of the x-ray pulse energy from damage produced on the surface of a Ti foil in the far field of the source gives a pulse energy of 20-30 μJ, a range that correlates well with the observation of the spectral hole burning and indicates an overall extraction efficiency of ∼10%. (letter to the editor)

Photoionization from metastable (1s2s) 1Se and 3Se states of the He atom for energies between the N=2 and 3 thresholds of He+

International Nuclear Information System (INIS)

Zhou, B.; Lin, C.D.

1994-01-01

Photoionization cross sections from the metastable state (1s2s) 1 Se of the He atom for photon energies between the He + (N=2) and (N=3) thresholds are calculated using the hyperspherical close-coupling method. The calculated spectra are convoluted with an energy resolution of 5.4 meV and are compared with the spectra for photoionization from the ground state. It is found that among the four possible outgoing channels, the 1sεp channel, which is the dominant channel for photoionization from the ground state, makes negligible contributions to the total cross sections for photoionization from the metastable state. As a result, the propensity rule derived from the ground-state photoionization no longer applies and more series of the doubly excited states are populated with significant spectral intensity in photoionization from the metastable state. Photoionization cross sections from the metastable (1s2s) 3 Se state are also calculated and analyzed

Excitation into 3p55p levels from the metastable levels of Ar

International Nuclear Information System (INIS)

Jung, R. O.; Boffard, John B.; Anderson, L. W.; Lin, Chun C.

2007-01-01

Measurements of cross sections for electron-impact excitation out of the J=0 and J=2 3p 5 4s metastable levels of argon into nine of the ten levels of the 3p 5 5p manifold are presented in the energy range from threshold to 10 eV. A mixed target of atoms in both metastable levels was created by a hollow cathode discharge. Laser quenching was used to depopulate either one of the metastable levels, allowing separate measurements of the cross sections from each of the two metastable levels. Unlike the metastable excitation cross sections into 3p 5 4p levels, the cross sections into the 3p 5 5p levels are not found to be proportional to optical oscillator strengths

Stellar laboratories . VIII. New Zr iv-vii, Xe iv-v, and Xe vii oscillator strengths and the Al, Zr, and Xe abundances in the hot white dwarfs G191-B2B and RE 0503-289

Science.gov (United States)

Rauch, T.; Gamrath, S.; Quinet, P.; Löbling, L.; Hoyer, D.; Werner, K.; Kruk, J. W.; Demleitner, M.

2017-03-01

Context. For the spectral analysis of high-resolution and high-signal-to-noise spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: To search for zirconium and xenon lines in the ultraviolet (UV) spectra of G191-B2B and RE 0503-289, new Zr iv-vii, Xe iv-v, and Xe vii oscillator strengths were calculated. This allows, for the first time, determination of the Zr abundance in white dwarf (WD) stars and improvement of the Xe abundance determinations. Methods: We calculated Zr iv-vii, Xe iv-v, and Xe vii oscillator strengths to consider radiative and collisional bound-bound transitions of Zr and Xe in our NLTE stellar-atmosphere models for the analysis of their lines exhibited in UV observations of the hot WDs G191-B2B and RE 0503-289. Results: We identified one new Zr iv, 14 new Zr v, and ten new Zr vi lines in the spectrum of RE 0503-289. Zr was detected for the first time in a WD. We measured a Zr abundance of -3.5 ± 0.2 (logarithmic mass fraction, approx. 11 500 times solar). We identified five new Xe vi lines and determined a Xe abundance of -3.9 ± 0.2 (approx. 7500 times solar). We determined a preliminary photospheric Al abundance of -4.3 ± 0.2 (solar) in RE 0503-289. In the spectra of G191-B2B, no Zr line was identified. The strongest Zr iv line (1598.948 Å) in our model gave an upper limit of -5.6 ± 0.3 (approx. 100 times solar). No Xe line was identified in the UV spectrum of G191-B2B and we confirmed the previously determined upper limit of -6.8 ± 0.3 (ten times solar). Conclusions: Precise measurements and calculations of atomic data are a prerequisite for advanced NLTE stellar-atmosphere modeling. Observed Zr iv-vi and Xe vi-vii line profiles in the UV spectrum of RE 0503-289 were simultaneously well reproduced with our newly calculated oscillator strengths. Based on observations

A high volume, batch mode {sup 129}Xe polarizer

Energy Technology Data Exchange (ETDEWEB)

Wojna-Pelczar, Anna, E-mail: anna.wojna.pelczar@mail.muni.cz [Central European Institute of Technology, Masaryk University, Brno (Czech Republic); Formerly: Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków (Poland); Pałasz, Tadeusz [Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków (Poland)

2017-06-01

Numerous designs of optical gas polarizers have been proposed, broadening possible applications of the hyperpolarized gases as contrast agents in magnetic resonance imaging. We present a home–made {sup 129}Xe polarizer based on the spin exchange optical pumping method. The polarizer operates under 1 bar of the gas mixture (at the maximum temperature of 160 °C) in a high volume optical cell (5025 cm{sup 3}). Approximately 100 cm{sup 3} of {sup 129}Xe polarized at 1.50±0.37% is produced in a single cycle of polarization. Operation under standard pressure imposes polarization transfer mainly via van der Waals molecules, resulting in the efficient spin exchange between rubidium and {sup 129}Xe atoms. The design, construction and operation of the polarizer are described in details.

Atomistic simulations of thermodynamic properties of Xe gas bubbles in U10Mo fuels

Energy Technology Data Exchange (ETDEWEB)

Hu, Shenyang, E-mail: shenyang.hu@pnnl.gov; Setyawan, Wahyu; Joshi, Vineet V.; Lavender, Curt A.

2017-07-15

Xe gas bubble superlattice formation is observed in irradiated uranium–10 wt% molybdenum (U10Mo) fuels. However, the thermodynamic properties of the bubbles (the relationship among bubble size, equilibrium Xe concentration, and bubble pressure) and the mechanisms of bubble superlattice formation are not well known. In this work, the molecular dynamics (MD) method is used to study these properties and mechanisms. The results provide important inputs for quantitative mesoscale models of gas bubble evolution and fuel performance. In the MD simulations, the embedded-atom method (EAM) potential of U10Mo-Xe [1] is employed. Initial gas bubbles with a low Xe concentration (underpressured) are generated in a body-centered cubic (bcc) U10Mo single crystal. Then Xe atoms are sequentially added into the bubbles one by one, and the evolution of pressure and dislocation emission around the bubbles is analyzed. The relationship between pressure, equilibrium Xe concentration, and radius of the bubbles is established. It was found that an overpressured gas bubble emits partial dislocations with a Burgers vector along the <111> direction and a slip plane of (11-2). Meanwhile, dislocation loop punch out was not observed. The overpressured bubble also induces an anisotropic stress field. A tensile stress was found along <110> directions around the bubble, favoring the nucleation and formation of a face-centered cubic bubble superlattice in bcc U10Mo fuels.

Atomistic simulations of thermodynamic properties of Xe gas bubbles in U10Mo fuels

Science.gov (United States)

Hu, Shenyang; Setyawan, Wahyu; Joshi, Vineet V.; Lavender, Curt A.

2017-07-01

Xe gas bubble superlattice formation is observed in irradiated uranium-10 wt% molybdenum (U10Mo) fuels. However, the thermodynamic properties of the bubbles (the relationship among bubble size, equilibrium Xe concentration, and bubble pressure) and the mechanisms of bubble superlattice formation are not well known. In this work, the molecular dynamics (MD) method is used to study these properties and mechanisms. The results provide important inputs for quantitative mesoscale models of gas bubble evolution and fuel performance. In the MD simulations, the embedded-atom method (EAM) potential of U10Mo-Xe [1] is employed. Initial gas bubbles with a low Xe concentration (underpressured) are generated in a body-centered cubic (bcc) U10Mo single crystal. Then Xe atoms are sequentially added into the bubbles one by one, and the evolution of pressure and dislocation emission around the bubbles is analyzed. The relationship between pressure, equilibrium Xe concentration, and radius of the bubbles is established. It was found that an overpressured gas bubble emits partial dislocations with a Burgers vector along the direction and a slip plane of (11-2). Meanwhile, dislocation loop punch out was not observed. The overpressured bubble also induces an anisotropic stress field. A tensile stress was found along directions around the bubble, favoring the nucleation and formation of a face-centered cubic bubble superlattice in bcc U10Mo fuels.

Anisotropic flow in Xe-Xe collisions at 5.44 TeV

CERN Document Server

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Naik, Bharati; Nair, Rahul; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Narayan, Amrendra; Naru, Muhammad Umair; Nassirpour, Adrian Fereydon; Ferreira Natal Da Luz, Pedro Hugo; Nattrass, Christine; Rosado Navarro, Sebastian; Nayak, Kishora; Nayak, Ranjit; Nayak, Tapan Kumar; Nazarenko, Sergey; Negrao De Oliveira, Renato Aparecido; Nellen, Lukas; Nesbo, Simon Voigt; Neskovic, Gvozden; Ng, Fabian; Nicassio, Maria; Niedziela, Jeremi; Nielsen, Borge Svane; Nikolaev, Sergey; Nikulin, Sergey; Nikulin, Vladimir; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Cabanillas Noris, Juan Carlos; Norman, Jaime; Nyanin, Alexander; Nystrand, Joakim Ingemar; Oh, Hoonjung; Ohlson, Alice Elisabeth; Oleniacz, Janusz; Oliveira Da Silva, Antonio Carlos; Oliver, Michael Henry; Onderwaater, Jacobus; Oppedisano, Chiara; Orava, Risto; Oravec, Matej; Ortiz Velasquez, Antonio; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Pachmayer, Yvonne Chiara; Pacik, Vojtech; Pagano, Davide; Paic, Guy; Palni, Prabhakar; Pan, Jinjin; Pandey, Ashutosh Kumar; Panebianco, Stefano; Papikyan, Vardanush; Pareek, Pooja; Park, Jonghan; Parkkila, Jasper Elias; Parmar, Sonia; Passfeld, Annika; Pathak, Surya Prakash; Patra, Rajendra Nath; Paul, Biswarup; Pei, Hua; Peitzmann, Thomas; Peng, Xinye; Pereira, Luis Gustavo; Pereira Da Costa, Hugo Denis Antonio; Peresunko, Dmitry Yurevich; Perez Lezama, Edgar; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petrovici, Mihai; Petta, Catia; Peretti Pezzi, Rafael; Piano, Stefano; Pikna, Miroslav; Pillot, Philippe; Ozelin De Lima Pimentel, Lais; Pinazza, Ombretta; Pinsky, Lawrence; Pisano, Silvia; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Planinic, Mirko; Pliquett, Fabian; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polishchuk, Boris; Poljak, Nikola; Poonsawat, Wanchaloem; Pop, Amalia; Poppenborg, Hendrik; Porteboeuf, Sarah Julie; Pozdniakov, Valeriy; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puccio, Maximiliano; Punin, Valery; Putschke, Jorn Henning; Raha, Sibaji; Rajput, Sonia; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Rami, Fouad; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Ratza, Viktor; Ravasenga, Ivan; Read, Kenneth Francis; Redlich, Krzysztof; Rehman, Attiq Ur; Reichelt, Patrick Simon; Reidt, Felix; Ren, Xiaowen; Renfordt, Rainer Arno Ernst; Reshetin, Andrey; Revol, Jean-pierre; Reygers, Klaus Johannes; Riabov, Viktor; Richert, Tuva Ora Herenui; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Ristea, Catalin-lucian; Rode, Sudhir Pandurang; Rodriguez Cahuantzi, Mario; Roeed, Ketil; Rogalev, Roman; Rogochaya, Elena; Rohr, David Michael; Roehrich, Dieter; Rokita, Przemyslaw Stefan; Ronchetti, Federico; Dominguez Rosas, Edgar; Roslon, Krystian; Rosnet, Philippe; Rossi, Andrea; Rotondi, Alberto; Roukoutakis, Filimon; Roy, Christelle Sophie; Roy, Pradip Kumar; Vazquez Rueda, Omar; Rui, Rinaldo; Rumyantsev, Boris; Rustamov, Anar; Ryabinkin, Evgeny; Ryabov, Yury; Rybicki, Andrzej; Saarinen, Sampo; Sadhu, Samrangy; Sadovskiy, Sergey; Safarik, Karel; Saha, Sumit Kumar; Sahoo, Baidyanath; Sahoo, Pragati; Sahoo, Raghunath; Sahoo, Sarita; Sahu, Pradip Kumar; Saini, Jogender; Sakai, Shingo; Saleh, Mohammad Ahmad; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sandoval, Andres; Sarkar, Amal; Sarkar, Debojit; Sarkar, Nachiketa; Sarma, Pranjal; Sas, Mike Henry Petrus; Scapparone, Eugenio; Scarlassara, Fernando; Schaefer, Brennan; Scheid, Horst Sebastian; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schmidt, Marten Ole; Schmidt, Martin; Schmidt, Nicolas Vincent; Schukraft, Jurgen; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Sefcik, Michal; Seger, Janet Elizabeth; Sekiguchi, Yuko; Sekihata, Daiki; Selyuzhenkov, Ilya; Senosi, Kgotlaesele; Senyukov, Serhiy; Serradilla Rodriguez, Eulogio; Sett, Priyanka; Sevcenco, Adrian; Shabanov, Arseniy; Shabetai, Alexandre; Shahoyan, Ruben; Shaikh, Wadut; Shangaraev, Artem; Sharma, Anjali; Sharma, Ankita; Sharma, Meenakshi; Sharma, Natasha; Sheikh, Ashik Ikbal; Shigaki, Kenta; Shimomura, Maya; Shirinkin, Sergey; Shou, Qiye; Shtejer Diaz, Katherin; Sibiryak, Yury; Siddhanta, Sabyasachi; Sielewicz, Krzysztof Marek; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Simatovic, Goran; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singh, Randhir; Singhal, Vikas; Sarkar - Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Slupecki, Maciej; Smirnov, Nikolai; Snellings, Raimond; Snellman, Tomas Wilhelm; Song, Jihye; Soramel, Francesca; Sorensen, Soren Pontoppidan; Sozzi, Federica; Sputowska, Iwona Anna; Stachel, Johanna; Stan, Ionel; Stankus, Paul; Stenlund, Evert Anders; Stocco, Diego; Storetvedt, Maksim Melnik; Strmen, Peter; Alarcon Do Passo Suaide, Alexandre; Sugitate, Toru; Suire, Christophe Pierre; Suleymanov, Mais Kazim Oglu; Suljic, Miljenko; Sultanov, Rishat; Sumbera, Michal; Sumowidagdo, Suharyo; Suzuki, Ken; Swain, Sagarika; Szabo, Alexander; Szarka, Imrich; Tabassam, Uzma; Takahashi, Jun; Tambave, Ganesh Jagannath; Tanaka, Naoto; Tarhini, Mohamad; Tariq, Mohammad; Tarzila, Madalina-gabriela; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terrevoli, Cristina; Teyssier, Boris; Thakur, Dhananjaya; Thakur, Sanchari; Thomas, Deepa; Thoresen, Freja; Tieulent, Raphael Noel; Tikhonov, Anatoly; Timmins, Anthony Robert; Toia, Alberica; Topilskaya, Nataliya; Toppi, Marco; Rojas Torres, Solangel; Tripathy, Sushanta; Trogolo, Stefano; Trombetta, Giuseppe; Tropp, Lukas; Trubnikov, Victor; Trzaska, Wladyslaw Henryk; Trzcinski, Tomasz Piotr; Trzeciak, Barbara Antonina; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ullaland, Kjetil; Umaka, Ejiro Naomi; Uras, Antonio; Usai, Gianluca; Utrobicic, Antonija; Vala, Martin; Van Hoorne, Jacobus Willem; Van Leeuwen, Marco; Vande Vyvre, Pierre; Varga, Dezso; Diozcora Vargas Trevino, Aurora; Vargyas, Marton; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vauthier, Astrid; Vazquez Doce, Oton; Vechernin, Vladimir; Veen, Annelies Marianne; Vercellin, Ermanno; Vergara Limon, Sergio; Vermunt, Luuk; Vernet, Renaud; Vertesi, Robert; Vickovic, Linda; Viinikainen, Jussi Samuli; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Villatoro Tello, Abraham; Vinogradov, Alexander; Virgili, Tiziano; Vislavicius, Vytautas; Vodopyanov, Alexander; Volkl, Martin Andreas; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; Von Haller, Barthelemy; Vorobyev, Ivan; Voscek, Dominik; Vranic, Danilo; Vrlakova, Janka; Wagner, Boris; Wang, Hongkai; Wang, Mengliang; Watanabe, Yosuke; Weber, Michael; Weber, Steffen Georg; Wegrzynek, Adam; Weiser, Dennis Franz; Wenzel, Sandro Christian; Wessels, Johannes Peter; Westerhoff, Uwe; Whitehead, Andile Mothegi; Wiechula, Jens; Wikne, Jon; Wilk, Grzegorz Andrzej; Wilkinson, Jeremy John; Willems, Guido Alexander; Williams, Crispin; Willsher, Emily; Windelband, Bernd Stefan; Witt, William Edward; Xu, Ran; Yalcin, Serpil; Yamakawa, Kosei; Yano, Satoshi; Yin, Zhongbao; Yokoyama, Hiroki; Yoo, In-kwon; Yoon, Jin Hee; Yurchenko, Volodymyr; Zaccolo, Valentina; Zaman, Ali; Zampolli, Chiara; Correa Zanoli, Henrique Jose; Zardoshti, Nima; Zarochentsev, Andrey; Zavada, Petr; Zavyalov, Nikolay; Zbroszczyk, Hanna Paulina; Zhalov, Mikhail; Zhang, Xiaoming; Zhang, Yonghong; Zhang, Zuman; Zhao, Chengxin; Zherebchevskii, Vladimir; Zhigareva, Natalia; Zhou, Daicui; Zhou, You; Zhou, Zhuo; Zhu, Hongsheng; Zhu, Jianhui; Zhu, Ya; Zichichi, Antonino; Zimmermann, Markus Bernhard; Zinovjev, Gennady; Zmeskal, Johann; Zou, Shuguang

2018-01-01

The first measurements of anisotropic flow coefficients $v_{n}$ for mid-rapidity charged particles in Xe-Xe collisions at $\\sqrt{s_{NN}}=5.44$ TeV are presented. Comparing these measurements to those from Pb-Pb collisions at $\\sqrt{s_{NN}}=5.02$ TeV, $v_{2}$ is found to be suppressed for mid-central collisions at the same centrality, and enhanced for central collisions. The values of $v_{3}$ are generally larger in Xe-Xe than in Pb-Pb at a given centrality. These observations are consistent with expectations from hydrodynamic predictions. When both $v_{2}$ and $v_{3}$ are divided by their corresponding eccentricities for a variety of initial state models, they generally scale with transverse density when comparing Xe-Xe and Pb-Pb, with some deviations observed in central Xe-Xe and Pb-Pb collisions. These results assist in placing strong constraints on both the initial state geometry and medium response for relativistic heavy-ion collisions.

Search for the permanent electric dipole moment of 129Xe

Science.gov (United States)

Sachdeva, Natasha; Chupp, Timothy; Gong, Fei; Babcock, Earl; Salhi, Zahir; Burghoff, Martin; Fan, Isaac; Killian, Wolfgang; Knappe-Grüneberg, Silvia; Schabel, Allard; Seifert, Frank; Trahms, Lutz; Voigt, Jens; Degenkolb, Skyler; Fierlinger, Peter; Krägeloh, Eva; Lins, Tobias; Marino, Michael; Meinel, Jonas; Niessen, Benjamin; Stuiber, Stefan; Terrano, William; Kuchler, Florian; Singh, Jaideep

2017-09-01

CP-violation in Beyond-the-Standard-Model physics, necessary to explain the baryon asymmetry, gives rise to permanent electric dipole moments (EDMs). EDM measurements of the neutron, electron, paramagnetic and diamagnetic atoms constrain CP-violating parameters. The current limit for the 129Xe EDM is 6 ×10-27 e . cm (95 % CL). The HeXeEDM experiment at FRM-II (Munich Research Reactor) and BMSR-2 (Berlin Magnetically Shielded Room) uses a stable magnetic field in a magnetically shielded room and 3He comagnetometer with potential to improve the limit by two orders of magnitude. Polarized 3He and 129Xe free precession is detected with SQUID magnetometers in the presence of applied electric and magnetic fields. Conclusions from recent measurements will be presented.

Metastable enhancement of C+ and O+ capture reactions

International Nuclear Information System (INIS)

Thomas, E.W.; Moran, T.F.

1990-09-01

Single electron capture by 10- to 500-eV singly charged C and O ions traversing targets of H 2 and H was studied with emphasis on comparing cross sections for metastable species with those for the ground state. For an H 2 target cross sections are of the order 10 Angstrom and 20 to 30 times larger than for ground state species. Electron impact ion sources typically produce 5 to 30% of their output in the metastable state. Previous published work has largely ignored (or failed to detect) the presence of metastables and is incorrect by as much as an order of magnitude. Discrepancies between data sets have been resolved, and a reliable data set is provided for energies from 10 to 10 5 eV. Similar experiments for an atomic H target are underway. It is proposed to extend the program to similar studies with multiply charged projectile species

Determination of 131mXe and 133mXe in the presence of 133gXe via combined beta-spectroscopy and delayed coincidence

International Nuclear Information System (INIS)

Reeder, P.L.; Bowyer, T.W.; McIntyre, J.I.; Pitts, W.K.

2001-01-01

The International Monitoring System for the Comprehensive Nuclear-Test-Ban Treaty will include measurements of Xe fission products. Pacific Northwest National Laboratory has developed an automated system for separating Xe from air which detects Xe fission products using a beta-gamma counting system for 131m Xe, 133m Xe, 133g Xe, and 135g Xe. Betas and conversion electrons are detected in a plastic scintillation cell containing the Xe sample. Gamma and X-rays are detected in a NaI(Tl) scintillation detector which surrounds the plastic scintillator sample cell. Two-dimensional pulse-height spectra of gamma-energy versus beta-energy are obtained. The plastic scintillator spectrum in coincidence with the 31-keV X-rays from 131m Xe. 133m Xe, and 133g Xe is a complex mixture of conversion electrons and betas. A new technique to simultaneously measure the delayed coincidence (T 1/2 = 6.27 ns) between beta-particles from 133g Xe and conversion electrons depopulating the 81-keV state in 133 Cs is being developed. This technique allows separation of the 133g Xe beta spectrum from the conversion electrons due to 131m Xe and 133m Xe and uniquely quantifies all three nuclides. (author)

Determination of 131m Xe and 133m Xe in the presence of 133gXe via combined beta-spectroscopy and delayed coincidence

International Nuclear Information System (INIS)

Reeder, Paul L.; Bowyer, Ted W.; McIntyre, Justin I.; Pitts, W K.

2001-01-01

The International Monitoring System for the Comprehensive Nuclear-Test-Ban Treaty will include measurements of Xe fission products. Pacific Northwest National Laboratory has developed an automated system for separating Xe from air which detects Xe fission products using a beta-gamma counting system for 131mXe, 133mXe, 133Xe, and 135Xe. Betas and conversion electrons are detected in a plastic scintillation cell containing the Xe sample. Gamma and X-rays are detected in a NaI(Tl) scintillation detector which surrounds the plastic scintillator sample cell. Two-dimensional pulse height spectra of gamma energy versus beta energy are obtained. The plastic scintillator spectrum in coincidence with the 31-keV X-rays from 131mXe. 133mXe, and 133Xe is a complex mixture of conversion electrons and betas. A new technique to simultaneously measure the delayed coincidence (t1/2 = 6.27 ns) between beta particles from 133Xe and conversion electrons depopulating the 81-keV state in 133Cs is being developed. This technique will allow separation of the 133Xe spectrum from the conversion electrons due to 131mXe and 133mXe and will uniquely quantify all three nuclides

Superfluorescence with cold trapped neon atoms

International Nuclear Information System (INIS)

Zachorowski, Jerzy

2003-01-01

A method for observation of superfluorescence in a cloud of cold metastable Ne atoms is proposed. Means of achieving a cold sample of trapped metastable atoms are discussed. The feasibility of obtaining conditions for a superfluorescence pulse is studied. The paper also discusses the prospects for obtaining intense pulses of extreme ultraviolet radiation

Low-lying levels of 129Xe and 131Xe

International Nuclear Information System (INIS)

Palmer, D.C.; Irving, A.D.; Forsyth, P.D.; Hall, I.; Martin, D.G.E.; Maynard, M.J.

1978-01-01

The nuclei 129 Xe and 131 Xe have been studied by Coulomb excitation and by (α, n) reactions on 126 Te and 128 Te. Eleven new levels for 129 Xe and six for 131 Xe and B(E2) transition values for some of the low-lying states are reported. The present Coulomb excitation experiments together with published β-decay work enable some spin-parity assignments and restrictions to be made. The data are broadly consistent with the predictions of the particle-vibrator coupling model, although a thorough comparison requires further spectroscopic measurements and more detailed theoretical calculation. (author)

Hydrodynamic predictions for 5.44 TeV Xe+Xe collisions

Science.gov (United States)

Giacalone, Giuliano; Noronha-Hostler, Jacquelyn; Luzum, Matthew; Ollitrault, Jean-Yves

2018-03-01

We argue that relativistic hydrodynamics is able to make robust predictions for soft particle production in Xe+Xe collisions at the CERN Large Hadron Collider (LHC). The change of system size from Pb+Pb to Xe+Xe provides a unique opportunity to test the scaling laws inherent to fluid dynamics. Using event-by-event hydrodynamic simulations, we make quantitative predictions for several observables: mean transverse momentum, anisotropic flow coefficients, and their fluctuations. Results are shown as a function of collision centrality.

Inelastic collision rates of trapped metastable hydrogen

NARCIS (Netherlands)

Landhuis, D; Matos, L; Moss, SC; Steinberger, JK; Vant, K; Willmann, L; Greytak, TJ; Kleppner, D

We report the first detailed decay studies of trapped metastable (2S) hydrogen. By two-photon excitation of ultracold H samples, we have produced clouds of at least 5x10(7) magnetically trapped 2S atoms at densities greater than 4x10(10) cm(-3) and temperatures below 100 muK. At these densities and

Differential cross sections for the scattering of Na 2Ssub(1/2) and Na 2Psub(3/2) by Xe 1S0

International Nuclear Information System (INIS)

Deventer, J.M.M. van.

1980-01-01

An atomic crossed-beam apparatus has been built and tested in which experiments were carried out on the scattering of alkali atoms in the ground state and an excited state by inert neutral gas atoms or molecules in the thermal energy region. Measurements have been performed on Na/Xe and Na*/Xe systems to extract information about the interaction potentials. (G.T.H.)

Solid and liquid 129Xe NMR signals enhanced by spin-exchange optical pumping under flow

International Nuclear Information System (INIS)

Zhou Xin; Luo Jun; Sun Xianping; Zeng Xizhi; Liu Maili; Liu Wuyang

2002-01-01

Laser-polarized 129 Xe gas was produced by spin-exchange with Cs atom optically pumped with diode laser array in a low field under flow. The nuclear spin polarizations of the solid and liquid 129 Xe frozen from the laser-polarized 129 Xe gas were 2.16% and 1.45% respectively in the SY-80M NMR spectrometer, which corresponded to the enhancements of 6000 and 5000 compared to those without optical pumping under the same conditions. It could provide the base and possibility for quantum computers using laser-enhanced solid and liquid 129 Xe. Polarization loss of transport and state change was also discussed

Symmetric resonance double charge transfer in Kr++ + Kr and Xe++ + Xe systems

International Nuclear Information System (INIS)

Okuno, K.; Koizumi, T.; Kaneko, Y.

1978-01-01

Cross sections of processes Kr ++ + Kr → Ke + Kr ++ and Xe ++ + Xe → Xe + Xe ++ were measured by the injected-ion-drift-tube technique from 0.04 to 20 eV. For both cases, the cross section below 1 eV coincides with the orbiting cross sections with a charge-transfer probability 1/2. Above 1 eV, the energy dependence of the cross sectcion is like that for single charge transfer. Mobilities of Kr ++ and Xe ++ in He are presented also

An investigation of Ar metastable state density in low pressure dual-frequency capacitively coupled argon and argon-diluted plasmas

International Nuclear Information System (INIS)

Liu, Wen-Yao; Xu, Yong; Peng, Fei; Guo, Qian; Li, Xiao-Song; Zhu, Ai-Min; Liu, Yong-Xin; Wang, You-Nian

2015-01-01

An tunable diode laser absorption spectroscopy has been used to determine the Ar*( 3 P 2 ) and Ar*( 3 P 0 ) metastable atoms densities in dual-frequency capacitively coupled plasmas. The effects of different control parameters, such as high-frequency power, gas pressure and content of Ar, on the densities of two metastable atoms and electron density were discussed in single-frequency and dual-frequency Ar discharges, respectively. Particularly, the effects of the pressure on the axial profile of the electron and Ar metastable state densities were also discussed. Furthermore, a simple rate model was employed and its results were compared with experiments to analyze the main production and loss processes of Ar metastable states. It is found that Ar metastable state is mainly produced by electron impact excitation from the ground state, and decayed by diffusion and collision quenching with electrons and neutral molecules. Besides, the addition of CF 4 was found to significantly increase the metastable destruction rate by the CF 4 quenching, especially for large CF 4 content and high pressure, it becomes the dominant depopulation process

Confinement and correlation effects in the Xe-C{sub 60} generalized oscillator strengths

Energy Technology Data Exchange (ETDEWEB)

Amusia, M. Ya. [Racah Institute of Physics, Hebrew University, 91904 Jerusalem (Israel); A. F. Ioffe Physical-Technical Institute, 194021 St. Petersburg (Russian Federation); Chernysheva, L. V. [A. F. Ioffe Physical-Technical Institute, 194021 St. Petersburg (Russian Federation); Dolmatov, V. K. [Department of Physics and Earth Science, University of North Alabama, Florence, Alabama 35632 (United States)

2011-12-15

The impact of both confinement and electron correlation on generalized oscillator strengths (GOS's) of endohedral atoms, A-C{sub 60}, is theoretically studied choosing the Xe-C{sub 60} 4d, 5s, and 5p fast electron impact ionization as the case study. Calculations are performed in the transferred to the atom energy region beyond the 4d threshold, {omega}=75-175 eV. The calculation methodology combines the plane-wave Born approximation, Hartree-Fock approximation, and random-phase approximation with exchange in the presence of the C{sub 60} confinement. The confinement is modeled by a spherical {delta}-function-like potential as well as by a square well potential to evaluate the effect of the finite thickness of the C{sub 60} cage on the Xe-C{sub 60} GOS's. Dramatic distortion of the 4d, 5p, and 5s GOS's by the confinement is demonstrated, compared to the free atom. Considerable contributions of multipolar transitions beyond dipole transitions in the calculated GOS's are revealed, in some instances. The vitality of accounting for electron correlation in calculation of the Xe-C{sub 60} 5s and 5p GOS's is shown.

Comprehensive sets of 124Xe(n ,γ )125Xe and 124Xe(n ,2 n )123Xe cross-section data for assessment of inertial-confinement deuterium-tritium fusion plasma

Science.gov (United States)

Bhike, Megha; Fallin, B.; Gooden, M. E.; Ludin, N.; Tornow, W.

2015-01-01

Measurements of the neutron radiative-capture cross section of 124Xe have been performed for the first time for neutron energies above 100 keV. In addition, data for the 124Xe(n ,2 n )123Xe reaction cross section have been obtained from threshold to 14.8 MeV to cover the entire energy range of interest, while previous data existed only at around 14 MeV. The results of these measurements provide the basis for an alternative and sensitive diagnostic tool for investigating properties of the inertial confinement fusion plasma in deuterium-tritium (DT) capsules at the National Ignition Facility located at Lawrence Livermore National Laboratory. Here, areal density ρ R (density × radius) of the fuel, burn asymmetry, and fuel-ablator mix are of special interest. The 124Xe(n ,γ )125Xe reaction probes the down-scattered neutrons, while the 124Xe(n ,2 n )123Xe reaction provides a measure of the 14 MeV direct neutrons.

Observation of double resonant laser induced transitions in the $v = n - l - 1 = 2$ metastable cascade of antiprotonic helium-4 atoms

CERN Document Server

Hayano, R S; Tamura, H; Torii, H A; Hori, Masaki; Maas, F E; Morita, N; Kumakura, M; Sugai, I; Hartmann, F J; Daniel, H; Von Egidy, T; Ketzer, B; Pohl, R; Horváth, D; Eades, John; Widmann, E; Yamazaki, T

1997-01-01

A new laser-induced resonant transition in the $v=n-l-1=2$ metastable cascade of antiprotonic $^4$He atoms has been found by using a double resonance technique. This was done by setting the first laser to the already known 470.724 nm resonance ($(n,l)=(37,34)\\rightarrow (36,33)$), while the $(38,35)\\rightarrow (37,34)$ transition was searched for with the second laser. The resonant transition was found at wavelength of 529.622$\\pm$0.003 nm, showing excellent agreement with a recent prediction of Korobov.

Ab initio effective core potentials including relativistic effects. II. Potential energy curves for Xe2, Xe+2, and Xe*2

International Nuclear Information System (INIS)

Ermler, W.C.; Lee, Y.S.; Pitzer, K.S.; Winter, N.W.

1978-01-01

Potential energy curves for the ground 1 Σ + /sub g/ state of Xe 2 , the first four states of the Xe + 2 ions, and the eight Xe* 2 excimer states corresponding to the addition of a 6ssigma/sub g/ Rydberg electron to these ion cores have been computed using averaged relativistic effective core potentials (AREP) and the self-consistent field approximation for the valence electrons. The calculations were carried out using the LS-coupling scheme with the effects of spin--orbit coupling included in the resulting potential energy curves using an empirical procedure. A comparison of nonrelativistic and averaged relativistic EP's and subsequent molecular calculations indicates that relativistic effects arising from the mass--velocity and Darwin terms are not important for these properties of Xe 2 molecules. Spectroscopic constants for Xe + 2 are in good agreement with all electron CI calculations suggesting that the computed values for Xe* 2 excimers should be reliable. The lifetime for the O/sub u/ + state of the Xe 2 * is computed to be 5.6 nsec which is in the range of the experimentally determined values

The mechanism of three-body process of energy transfer from excited xenon atoms to molecules

International Nuclear Information System (INIS)

Wojciechowski, K.; Forys, M.

1999-01-01

The mechanism of energy transfer from Xe(6 s[3/2] 1 ) resonance state (E=8.44 eV) and higher excited Xe(6p, 6p', 6 d) atoms produced in pulse radiolysis to molecules have been discussed. The analysis of the kinetic data for these processes shows that in the sensitized photolysis and radiolysis of Xe-M mixtures the excited atoms decay in 'ordinary' two-body reaction: Xe(6s[3/2] 1 0 )+M→products (r.1) and in fast 'accelerated' third order process: Xe(6s[3/2] 1 0 )+M+Xe→products (r.2) The discussion shows that three-body process occurs via reactions: Xe(6s[3/2] 1 0 )+Xe k w ↔ k d Xe 2 ** (r.2a) Xe 2 **+M k q →[Xe 2 M]*→products (r.2b) It was shown that this mechanism concerns also higher excited Xe atoms and can explain a similar process in He-M mixtures and suggests that it is a general mechanism of energy transfer in all irradiated rare gas-molecule systems

Formation and annealing of metastable (interstitial oxygen)-(interstitial carbon) complexes in n- and p-type silicon

CERN Document Server

Makarenko, L F; Lastovskii, S B; Murin, L I; Moll, M; Pintilie, I

2014-01-01

It is shown experimentally that, in contrast to the stable configuration of (interstitial carbon)-(interstitial oxygen) complexes (CiOi), the corresponding metastable configuration (CiOi{*}) cannot be found in n-Si based structures by the method of capacitance spectroscopy. The rates of transformation CiOi{*} -> CiOi are practically the same for both n- and p-Si with a concentration of charge carriers of no higher than 10(13) cm(-3). It is established that the probabilities of the simultaneous formation of stable and metastable configurations of the complex under study in the case of the addition of an atom of interstitial carbon to an atom of interstitial oxygen is close to 50\\%. This is caused by the orientation dependence of the interaction potential of an atom of interstitial oxygen with an interstitial carbon atom, which diffuses to this oxygen atom.

Isotope Shifts and Hyperfine Structure in the[Xe]4f(7)5d 6s(2) D-2(J)->[Xe]4f(7)5d 6s 6p F-9(J+1) Transitions of Gadolinium

International Nuclear Information System (INIS)

Blaum, K.; Bushaw, Bruce A.; Diel, S; Geppert, Ch; Kuschnick, A; Muller, P.; Nortershauser, W.; Schmitt, A.; Wendt, K.

1999-01-01

High-resolution resonance ionization mass spectrometry has been used to measure isotope shifts and hyperfine structure in all[Xe] 4f 7 5d 6s2 9DJ ---[Xe] 4f 7 5d 6s 6p 9FJ+1 (J= 2-6) and the[Xe] 4f 7 5d 6s2 9D6---[Xe] 4f 7 5d 6s 6p 9D5 transitions of gadolinium (Gd I). Gadolinium atoms in an atomic beam were excited with a tunable single-frequency laser in the wavelength range of 422 - 429 nm. Resonant excitation was followed by photoionization with the 363.8 nm line of an argon ion laser and resulting ions were mass separated and detected with a quadrupole mass spectrometer. Isotope shifts for all stable gadolinium isotopes in these transitions have been measured for the first time. Additionally, the hyperfine structure constants of the upper states have been derived for the isotopes 155, 157Gd and are compared with previous work. Using prior experimental values for the mean nuclear charge radii, derived from the combination of muonic atoms and electron scattering data, field shift a nd specific mass shift coefficients for the investigated transitions have been determined and nuclear charge parameters l for the minor isotopes 152, 154Gd have been calculated

Stark shift measurements of Xe II and Xe III spectral lines

International Nuclear Information System (INIS)

Cirisan, M; Pelaez, R J; Djurovic, S; Aparicio, J A; Mar, S

2007-01-01

Stark shift measurements of singly and doubly ionized Xe spectral lines are presented in this paper. Shifts of 110 Xe II lines and 42 Xe III lines are reported, including a significant number of new results. A low-pressure-pulsed arc with 95% of He and 5% of Xe was used as a plasma source. All measurements were performed under the following plasma conditions: electron density (0.2-1.4) x 10 23 m -3 and electron temperature 18 000-23 000 K. The measured Stark shifts are compared with other experimental and theoretical data

Wavelengths and energy levels of Xe V and Xe VI obtained by collision-based spectroscopy

International Nuclear Information System (INIS)

Larsson, M.O.; Gonzalez, A.M.; Hallin, R.; Heijkenskjoeld, F.; Nystroem, B.; O'Sullivan, G.; Weber, C.; Waennstroem, A.

1996-01-01

We have utilized collision-based spectroscopy to investigate the spectra of Xe V and Xe VI. The radiation emitted following electron capture by 50 keV Xe 5+ and 60 keV Xe 6+ ions impinging on a He (Ar) gas target has been recorded in the 350-6000 (1200-2500) A wavelength region. A number of new energy levels of Xe V and Xe VI have been established from lines identified by us. In particular, we have observed and identified transitions from the 5s 2 5p4f (5s 2 4f) configuration of Xe V (Xe VI). The analysis was supported by Hartree-Fock calculations. (orig.)

Photoassociation of cold metastable helium atoms

NARCIS (Netherlands)

Woestenenk, G.R.

2001-01-01

During the last decades the study of cold atoms has grown in a great measure. Research in this field has been made possible due to the development of laser cooling and trapping techniques. We use laser cooling to cool helium atoms down to a temperature of 1 mK and we are able to

Infrared Spectra of Novel NgBeSO2 Complexes (Ng = Ne, Ar, Kr, Xe) in Low Temperature Matrixes.

Science.gov (United States)

Yu, Wenjie; Liu, Xing; Xu, Bing; Xing, Xiaopeng; Wang, Xuefeng

2016-11-03

The novel noble-gas complexes NgBeSO 2 (Ng = Ne, Ar, Kr, Xe) have been prepared in the laser-evaporated beryllium atom reactions with SO 2 in low-temperature matrixes. Doped with heavier noble gas, the guest (Ar, Kr, Xe) atom can substitute neon to form more stable complex. Infrared spectroscopy and theoretical calculations are used to confirm the band assignment. The dissociation energies are calculated at 0.9, 4.0, 4.7, and 6.0 kcal/mol for NeBeSO 2 , ArBeSO 2 , KrBeSO 2 , and XeBeSO 2 , respectively, at the CCSD(T) level. Quantum chemical calculations demonstrate that the Ng-Be bonds in NgBeSO 2 could be formed by the combination of electron-donation and ion-induced dipole interactions. The Wiberg bond index (WBI) values of Ng-Be bonds and LOL (localized orbital locator) profile indicate that the Ng-Be bond exhibits a gradual increase in covalent character along Ne to Xe.

EPR investigation of electronic excitations in rare gas solids (Review Article)

Science.gov (United States)

Zhitnikov, R. A.; Dmitriev, Yu. A.

1998-10-01

The methods are described for producing unstable paramagnetic excited states in rare gas cryocrystals Ne, Ar, Kr, and Xe through the trapping, in the cryocrystals growing from the gas phase, the products of the gas discharge taking place in the same or other rare gas. The paper presents a technique and results of an observation and investigation of excited states in rare gas cryocrystals with electron paramagnetic resonance (EPR). The discovered unstable paramagnetic centers are interpreted as being local metastable excited np5(n+1)s atomic-type states in rare gas cryocrystals which are subject to the action of the anisotropic electric field resulted from the crystal surroundings distorted by the center. An account is given of the mechanisms for formation of observed paramagnetic excited states in cryocrystals which arise owing to the excitation energy of the metastable 3P2 atoms of Ne, Ar, Kr, Xe and He 23S1 and 21S0 atoms that form in the discharge in an appropriate gas and trap in the growing cryocrystal.

Production of 125I from amorphous films of Si doped with 124Xe and evaluation of its potential use in brachytherapy

International Nuclear Information System (INIS)

Leal, Alexandre S.; Viana, Gustavo A.

2015-01-01

This work describes the simulation of a new material that can be used in the brachytherapy treatment. The material consists of xenon-incorporated amorphous silicon (Xe@a-Si). The irradiated 124 Xe atoms of the samples are converted into 125 Xe, according to the reaction: 124 Xe (n,γ) 125 Xe that, in turn, decays to the radioisotope 125 I. A set of simulations performed using the MCNP5 code, shows that, in principle, the material proposed can be used in the seed of brachytherapy in the clinical treatment. (author)

A new search for the atomic EDM of {sup 129}Xe at FRM-II

Energy Technology Data Exchange (ETDEWEB)

Kuchler, F., E-mail: florian.kuchler@tum.de [Excellence Cluster Universe and Technische Universität München (Germany); Babcock, E. [Juelich Center for Neutron Science (Germany); Burghoff, M. [Physikalisch-Technische Bundesanstalt (Germany); Chupp, T.; Degenkolb, S. [University of Michigan (United States); Fan, I. [Physikalisch-Technische Bundesanstalt (Germany); Fierlinger, P. [Excellence Cluster Universe and Technische Universität München (Germany); Gong, F. [University of Michigan (United States); Kraegeloh, E. [Excellence Cluster Universe and Technische Universität München (Germany); Kilian, W.; Knappe-Grüneberg, S. [Physikalisch-Technische Bundesanstalt (Germany); Lins, T.; Marino, M.; Meinel, J.; Niessen, B. [Excellence Cluster Universe and Technische Universität München (Germany); Sachdeva, N. [University of Michigan (United States); Salhi, Z. [Juelich Center for Neutron Science (Germany); Schnabel, A.; Seifert, F. [Physikalisch-Technische Bundesanstalt (Germany); Singh, J. [Michigan State University and NSCL (United States); and others

2016-12-15

Permanent electric dipole moments (EDMs) arise due to the breaking of time-reversal or, equivalently, CP-symmetry. Although EDM searches have so far only set upper limits, which are many orders of magnitude larger than Standard Model (SM) predictions, the motivation for more sensitive searches is stronger than ever. A new effort at FRM-II incorporating {sup 129}Xe and {sup 3}He as a co-magnetometer can potentially improve the current limit. The noble gas mixture of {sup 129}Xe and {sup 3}He is simultanously polarized by spin-exchange optical pumping and then transferred into a high-performance magnetically shielded room. Inside, both species can freely precess in the presence of applied magnetic and electric fields. The precession signals are detected by LTc SQUID sensors. In EDM cells with silicon electrodes we observed spin lifetimes in excess of 2500 s without and with high-voltage applied. This meets one requirement to achieve our goal of improving the EDM limit on {sup 129}Xe by several orders of magnitude.

Structure and stability of solid Xe(H2)n

International Nuclear Information System (INIS)

Somayazulu, Maddury; Hemley, Russell J.; Dera, Przemyslaw; Smith, Jesse

2015-01-01

Mixtures of xenon and molecular hydrogen form a series of hexagonal, van der Waals compounds at high pressures and at 300 K. Synchrotron, x-ray, single crystal diffraction studies reveal that below 7.5 GPa, Xe(H 2 ) 8 crystallizes in a P3 - m1 structure that displays pressure-induced occupancy changes of two pairs of xenon atoms located on the 2c and 2d sites (while the third pair on yet another 2c site remains fully occupied). The occupancy becomes 1 at the P3 - m1 to R3 transition and all the xenon atoms occupy the 3d sites in the high-pressure structure. These pressure-induced changes in occupancy coincide with volume changes that maintain the average Xe:H 2 stoichiometry fixed at 1:8. The synchrotron x-ray diffraction and Raman measurements show that this unique hydrogen-bearing compound that can be synthesized at 4.2 GPa and 300 K, quenched at low temperatures to atmospheric pressure, and retained up to 90 K on subsequent warming

Excimer lasers utilizing XeF and XeCl molecules

Energy Technology Data Exchange (ETDEWEB)

Bychkov, Yu I; Konovalov, I N; Losev, V F; Mesyats, G A; Ryzhov, V V; Tarasenko, V F; Fedorov, A I; Shemyakina, S B; Yastremskii, A G

1978-12-01

The results are given of an experimental and theoretical study of XeF (wavelength approx. 350 nm) and XeCl (wavelength approx. 308 nm) lasers excited by an electron beam, a discharge stabilized by an electron beam, and a rapid discharge. These lasers are representative of ones employing halides of noble gases, which are the most powerful sources of stimulated emission in the uv region. The XeCl laser is shown to have good emission characteristics with various methods of excitation. An analysis of the kinetics of processes in the plasma of lasers utilizing halides of noble gases showed that the main channel for the transfer of the beam's energy to the formation of excimer molecules is the ionic channel. An efficiency of about 2.6 percent and a specific radiant energy of 10 J.l/sup -1/ showed that XeCl* is one of the most effective excimer molecules.

Probing zeolite internal structures using very low temperature 129Xe NMR

International Nuclear Information System (INIS)

Labouriau, A.; Crawford, S.N.; Earl, W.L.; Pietrass, T.; Weber, W.A.; Panjabi, G.; Gates, B.C.

1998-01-01

In recent years, probing pore structure with 129 Xe NMR has received a bad reputation. This is due to the fact that the method is more complex than was originally suggested so the data is somewhat difficult to interpret. The authors find that the use of a wide temperature range (40--350 K) allows them to interpret 129 Xe chemical shifts in terms of van der Waals attraction between the xenon atom and oxygen in zeolite walls. Using rather simple models from the literature, they can extract useful pore size information as well as the van der Waals potential energy

Spectra of copperlike and zinclike xenon: Xe XXV and Xe XXVI

International Nuclear Information System (INIS)

Kaufman, V.; Sugar, J.; Rowan, W.L.

1988-01-01

The spectra of highly ionized xenon were generated in a tokamak plasma and photographed in the region 60--350 A with a 2.2-m grazing-incidence spectrograph. The 4s 2 --4s4p transitions of Zn-like xenon (Xe XXV) and all the 4l--4(l+1) transitions of Cu-like xenon (Xe XXVI) were measured with estimated uncertainties of +- 0.005 A. These measurements have been combined with previous wavelength measurements of Xe XXVI to determine energy levels. A value for the ionization energy of Xe 25+ of 6 912 400 +- 3000 cm -1 (857.0 +- 0.4 eV) was derived

Electrically induced metastability in SI-GaAs studied by positron lifetime spectroscopy

International Nuclear Information System (INIS)

Luo, Y.L.; Beling, C.D.; Fung, S.; Ling, C.C.; Lui, M.K.; Mui, W.K.

2001-01-01

Recently, a room temperature electrically induced metastability in semi-insulating (SI)-GaAs has been reported in which the normally high resistance state of SI-GaAs converts into a low resistance state when breakdown electric fields are applied to the metal/Si-GaAs/metal system. The low resistance state persists when the electric field is lowered below the breakdown bias and as such may thus be considered as metastable state of the material. To clarify whether the high field breakdown has its origins in some atomic configurational change induced through high energy electron collisions we have employed positron lifetime spectroscopy. Lifetime spectra that have been taken at the same bias in both the high current and low current phases show that the positron lifetime in the metastable state has no change within the experimental error from that of the normal state, thus suggesting that the metastability is most likely of purely electronic origin. (orig.)

Observation of K- and L-REC in 200 MeV/u Xe54+-N2 collisions at HIRFL-CSR

International Nuclear Information System (INIS)

Yu Deyang; Xue Yingli; Shao Caojie; Song Zhangyong; Lu Rongchun; Ruan Fangfang; Wang Wei; Chen Jing; Yang Bian; Yang Zhihu; Wan Jianjie; Dong Chenzhong; Cai Xiaohong

2011-01-01

The 200 MeV/u Xe 54+ ions were utilized to collide with N 2 molecules and the K- and L-REC, as well as the Lyman lines of Xe 53+ were observed. After electron cooling, the ion beam momentum spread ΔP/P ∼ 2.2 x 10 -5 was achieved and the target thickness was stabilized at about 10 13 atom/cm 2 . As the first atomic experiment at HIRFL-CSR with the internal target, its feasibility and stability were verified.

Reactive quenching of two-photon excited xenon atoms by Cl2

International Nuclear Information System (INIS)

Bruce, M.R.; Layne, W.B.; Meyer, E.; Keto, J.W.

1987-01-01

Total binary and tertiary quench rates have been measured for the reaction Xe (5p 5 6p) + Cl 2 at thermal temperatures. Xenon atoms are excited by state-selective, two-photon absorption with a uv laser. The time dependent fluorescence from the excited atom in the IR and from XeCl* (B) product near 308 nm have been measured with subnanosecond time resolution. The decay rates are measured as a function of Cl 2 pressure to 20 Torr and Xe pressure to 400 Torr. The measured reaction rates (k 2 ∼ 10 -9 cm 3 sec -1 ) are consistent with a harpoon model described in a separate paper. We also measure large termolecular reaction rates for collisions with xenon atoms (k 3 ∼ 10 -28 cm 6 sec -1 ). Total product fluorescence has been examined using a gated optical multichannel analyzer. We measure unit branching fractions for high vibrational levels of XeCl* (B) with very little C state fluorescence observed. The measured termolecular rates suggest similar processes will dominate at the high buffer-gas pressures used in XeCl lasers. The effect of these large reactive cross sections for neutral xenon atoms on models of the XeCl laser will be discussed

Fast neutron spectroscopy with tensioned metastable fluid detectors

Energy Technology Data Exchange (ETDEWEB)

Grimes, T.F.; Taleyarkhan, R.P., E-mail: rusi@purdue.edu

2016-09-11

This paper describes research into development of a rapid-turnaround, neutron-spectroscopy capable (gamma-beta blind), high intrinsic efficiency sensor system utilizing the tensioned metastable fluid detector (TMFD) architecture. The inability of prevailing theoretical models (developed successfully for the classical bubble chamber) to adequately predict detection thresholds for tensioned metastable fluid conditions is described. Techniques are presented to overcome these inherent shortcomings, leading thereafter, to allow successful neutron spectroscopy using TMFDs – via the newly developed Single Atom Spectroscopy (SAS) approach. SAS also allows for a unique means for rapidly determining neutron energy thresholds with TMFDs. This is accomplished by simplifying the problem of determining Cavitation Detection Events (CDEs) arising from neutron interactions with one in which several recoiling atom species contribute to CDEs, to one in which only one dominant recoil atom need be considered. The chosen fluid is Heptane (C{sub 7}H{sub 16}) for which only recoiling C atoms contribute to CDEs. Using the SAS approach, the threshold curve for Heptane was derived using isotope neutron source data, and then validated against experiments with mono-energetic (2.45/14 MeV) neutrons from D-D and D-T accelerators. Thereafter the threshold curves were used to produce the response matrix for various geometries. The response matrices were in turn combined with experimental data to recover the continuous spectra of fission (Cf-252) and (α,n) Pu–Be isotopic neutron sources via an unfolding algorithm. A generalized algorithm is also presented for performing neutron spectroscopy using any other TMFD fluid that meets the SAS approach assumptions.

Growth kinetics of metastable (331) nanofacet on Au and Pt(110) surfaces

International Nuclear Information System (INIS)

Ndongmouo, U.T.; Houngninou, E.; Hontinfinde, F.

2006-12-01

A theoretical epitaxial growth model with realistic barriers for surface diffusion is investigated by means of kinetic Monte Carlo simulations to study the growth modes of metastable (331) nanofacets on Au and Pt(110) surfaces. The results show that under experimental atomic fluxes, the (331) nanofacets grow by 2D nucleation at low temperature in the submonolayer regime. A metastable growth phase diagram that can be useful to experimentalists is presented and looks similar to the one found for the stationary growth of the bcc(001) surface in the kinetic 6-vertex model. (author)

Trapping cold ground state argon atoms for sympathetic cooling of molecules

OpenAIRE

Edmunds, P. D.; Barker, P. F.

2014-01-01

We trap cold, ground-state, argon atoms in a deep optical dipole trap produced by a build-up cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of co-trapped metastable argon atoms using a new type of parametric loss spectroscopy. Using this technique we als...

Temperature enhancement of Xe(L) x-ray amplifier (λ ∼ 2.9 A) emission

International Nuclear Information System (INIS)

Borisov, Alex B; Zhang Ping; Racz, Ervin; McCorkindale, John C; Khan, Shahab F; Poopalasingam, Sankar; Zhao Ji; Rhodes, Charles K

2007-01-01

Cooling of the xenon nozzle flow to T = 230 K produces three leading effects. They are (1) a ∼2.5-fold enhancement of the Xe(L) hollow atom emission on the single-vacancy 3d → 2p charge state arrays (2) the production of amplifying self-trapped plasma channels with significantly enhanced lengths and (3) very sharply augmented emission on (2s-bar2p-bar) Xe(L) double-vacancy transitions in the λ ≅ 2.80 A region. (fast track communication)

Temperature enhancement of Xe(L) x-ray amplifier ({lambda} {approx} 2.9 A) emission

Energy Technology Data Exchange (ETDEWEB)

Borisov, Alex B [Laboratory for X-Ray Microimaging and Bioinformatics, Department of Physics, University of Illinois at Chicago, Chicago, IL 60607-7059 (United States); Zhang Ping [Laboratory for X-Ray Microimaging and Bioinformatics, Department of Physics, University of Illinois at Chicago, Chicago, IL 60607-7059 (United States); Racz, Ervin [Laboratory for X-Ray Microimaging and Bioinformatics, Department of Physics, University of Illinois at Chicago, Chicago, IL 60607-7059 (United States); McCorkindale, John C [Laboratory for X-Ray Microimaging and Bioinformatics, Department of Physics, University of Illinois at Chicago, Chicago, IL 60607-7059 (United States); Khan, Shahab F [Laboratory for X-Ray Microimaging and Bioinformatics, Department of Physics, University of Illinois at Chicago, Chicago, IL 60607-7059 (United States); Poopalasingam, Sankar [Laboratory for X-Ray Microimaging and Bioinformatics, Department of Physics, University of Illinois at Chicago, Chicago, IL 60607-7059 (United States); Zhao Ji [Laboratory for X-Ray Microimaging and Bioinformatics, Department of Physics, University of Illinois at Chicago, Chicago, IL 60607-7059 (United States); Rhodes, Charles K [Laboratory for X-Ray Microimaging and Bioinformatics, Department of Physics, University of Illinois at Chicago, Chicago, IL 60607-7059 (United States)

2007-11-28

Cooling of the xenon nozzle flow to T = 230 K produces three leading effects. They are (1) a {approx}2.5-fold enhancement of the Xe(L) hollow atom emission on the single-vacancy 3d {yields} 2p charge state arrays (2) the production of amplifying self-trapped plasma channels with significantly enhanced lengths and (3) very sharply augmented emission on (2s-bar2p-bar) Xe(L) double-vacancy transitions in the {lambda} {approx_equal} 2.80 A region. (fast track communication)

Energy levels and radiative rates for transitions in B-like to F-like Xe ions (Xe L-XLVI)

International Nuclear Information System (INIS)

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

2010-01-01

Energy levels, radiative rates, oscillator strengths, line strengths, and lifetimes have been calculated for transitions in B-like to F-like Xe ions, Xe L-XLVI. For the calculations, a fully relativistic GRASP code has been adopted, and results are reported for all electric dipole, electric quadrupole, magnetic dipole, and magnetic quadrupole transitions among the lowest 125, 236, 272, 226, and 113 levels of Xe L, Xe XLIX, Xe XLVIII, Xe XLVII, and Xe XLVI, respectively, belonging to the n ≤ 3 configurations.

Ion mobilities in Xe/Ne and other rare-gas mixtures

Energy Technology Data Exchange (ETDEWEB)

Piscitelli, D; Pitchford, L C [Centre de Physique des Plasmas et Applications de Toulouse (CPAT), UMR 5002 CNRS, 118 route de Narbonne, 31062 Toulouse (France); Phelps, A V [JILA, University of Colorado and National Institute of Technology, Boulder, Colorado (United States); Urquijo, J de [Centro de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Post Office Box 48-3, 62251, 80309-0440 Cuernavaca, Moreno (Mexico); Basurto, E [Departmento de Ciencias Basicas, Universidad Autonoma Metropolitana, 02200 Mexico Distrito Federal (Mexico)

2003-10-01

The ion mobility or drift velocity data important for modeling glow discharges in rare gas mixtures are not generally available, nor are the ion-neutral scattering cross sections needed to calculate these data. In this paper we propose a set of cross sections for Xe{sup +} and Ne{sup +} collisions with Xe and Ne atoms. Ion mobilities at 300 K calculated using this cross section set in a Monte Carlo simulation are reported for reduced field strengths, E/N, up to 1500x10{sup -21} V m{sup 2}, in pure gases and in Xe/Ne mixtures containing 5% and 20% Xe/Ne, which are mixtures of interest for plasma display panels (PDPs). The calculated Xe{sup +} mobilities depend strongly on the mixture composition, but the Ne{sup +} mobility varies only slightly with increasing Xe in the mixture over the range studied here. The mobilities in pure gases compare well with available experimental values, and mobilities in gas mixtures at low E/N compare well with our recent measurements which will be published separately. Results from these calculations of ion mobilities are used to evaluate the predictions of Blanc's law and of the mixture rule proposed by Mason and Hahn [Phys. Rev. A 5, 438 (1972)] for determining the ion mobilities in mixtures from a knowledge of the mobilities in each of the pure gases. The mixture rule of Mason and Hahn is accurate to better than 10% at high field strengths over a wide range of conditions of interest for modeling PDPs. We conclude that a good estimate of ion mobilities at high E/N in Xe/Ne and other binary rare gas mixtures can be obtained using this mixture rule combined with known values of mobilities in parent gases and with the Langevin form for mobility of rare gas ions ion in other gases. This conclusion is supported by results in Ar/Ne mixtures which are also presented here.

Shear response of grain boundaries with metastable structures by molecular dynamics simulations

Science.gov (United States)

Zhang, Liang; Lu, Cheng; Shibuta, Yasushi

2018-04-01

Grain boundaries (GBs) can play a role as the favored locations to annihilate point defects, such as interstitial atoms and vacancies. It is thus highly probable that different boundary structures can be simultaneously present in equilibrium with each other in the same GB, and thus the GB achieves a metastable state. However, the structural transition and deformation mechanism of such GBs are currently not well understood. In this work, molecular dynamics simulations were carried out to study the multiple structures of a Σ5(310)/[001] GB in bicrystal Al and to investigate the effect of structural multiplicity on the mechanical and kinetic properties of such a GB. Different GB structures were obtained by changing the starting atomic configuration of the bicrystal model, and the GB structures had significantly different atomic density. For the Σ5(310) GB with metastable structures, GB sliding was the dominant mechanism at a low temperature (T = 10 K) under shear stress. The sliding mechanism resulted from the uncoordinated transformation of the inhomogeneous structural units. The nucleation of voids was observed during GB sliding at the low temperature, and the voids subsequently evolved to a nanocrack at the boundary plane. Increasing the temperature can induce the structural transition of local GB structures and can change their overall kinetic properties. GB migration with occasional GB sliding dominated the deformation mechanism at elevated temperatures (T = 300 and 600 K), and the migration process of the metastable GB structures is closely related to the thermally assisted diffusion mechanism.

Atomic collisions research with excited atomic species

International Nuclear Information System (INIS)

Hoogerland, M.D.; Gulley, R.J.; Colla, M.; Lu, W.; Milic, D.; Baldwin, K.G.H.; Buckman, S.J.

1999-01-01

Measurements and calculations of fundamental atomic collision and spectroscopic properties such as collision cross sections, reaction rates, transition probabilities etc. underpin the understanding and operation of many plasma and gas-discharge-based devices and phenomena, for example plasma processing and deposition. In almost all cases the complex series of reactions which sustains the discharge or plasma, or produces the reactive species of interest, has a precursor electron impact excitation, attachment, dissociation or ionisation event. These processes have been extensively studied in a wide range of atomic and molecular species and an impressive data base of collision cross sections and reaction rates now exists. However, most of these measurements are for collisions with stable atomic or molecular species which are initially in their ground electronic state. Relatively little information is available for scattering from excited states or for scattering from unstable molecular radicals. Examples of such species would be metastable excited rare gases, which are often used as buffer gases, or CF 2 radicals formed by electron impact dissociation in a CF 4 plasma processing discharge. We are interested in developing experimental techniques which will enable the quantitative study of such exotic atomic and molecular species. In this talk I would like to outline one such facility which is being used for studies of collisions with metastable He(2 3 S) atoms

Total and elastic electron scattering cross sections from Xe at intermediate and high energies

International Nuclear Information System (INIS)

Garcia, G; Pablos, J L de; Blanco, F; Williart, A

2002-01-01

Experimental total electron scattering cross sections from Xe in the energy range 300-5000 eV have been obtained with experimental errors of about 3%. The method was based on the measurement of the attenuation of a linear electron beam through a Xe gas cell in combination with an electron spectroscopy technique to analyse the energy of the transmitted electrons. Differential and integral elastic cross sections have been calculated using a scattering potential method which includes relativistic effects. The consistency of our theoretical and experimental results is also discussed in the paper. Finally, analytical formulae depending on two parameters, namely the number of target electrons and the atomic polarizability, are given to reproduce the experimental data for Ne, Ar, Kr and Xe in the energy range 500-10 000 eV

Study of a rare-gas transverse fast discharge

Science.gov (United States)

Chubb, D. L.; Michels, C. J.

1979-01-01

An experimental and analytical study of a Blumlein-type transverse fast discharge operating with He and Xe are presented. An electro-optical voltage probe was used to measure the discharge voltage, and the measured voltages were in agreement with the computed voltages. The analytical model was used to predict the dependence of the discharge efficiency for producing metastables and ions on the important plasma and external circuit parameters. In He the ion efficiency is greater than the metastable efficiency, while in Xe it is the opposite; the He ion efficiencies are much larger than in Xe, while Xe metastable efficiencies are much larger than in He. These differences between Xe and He are accounted by the large dissociative recombination rate of Xe compared with He.

Quasimolecular emission near the Xe(5p 56s 1,3 P 1 - 5p 6 1 S 0) and Kr (4p 55s 1,3 P 1 - 4p 6 1 S 0) resonance lines induced by collisions with He atoms

Science.gov (United States)

Alekseeva, O. S.; Devdariani, A. Z.; Grigorian, G. M.; Lednev, M. G.; Zagrebin, A. L.

2017-02-01

This study is devoted to the theoretical investigation of the quasimolecular emission of Xe*-He and Kr*-He collision pairs near the Xe (5p 56s 1,3 P 1 - 5p 6 1 S 0) and Kr (4p 55s 1,3 P 1 - 4p 6 1 S 0) resonance atomic lines. The potential curves of the quasimolecules Xe(5p 56s) + He and Kr(4p 55s) + He have been obtained with the use of the effective Hamiltonian and pseudopotential methods. Based on these potential curves the processes of quasimolecular emission of Xe*+He and Kr*+He mixtures have been considered and the spectral distributions I(ħΔω) of photons emitted have been obtained in the framework of quasistatic approximation.

Combining density functional theory (DFT) and pair distribution function (PDF) analysis to solve the structure of metastable materials: the case of metakaolin.

Science.gov (United States)

White, Claire E; Provis, John L; Proffen, Thomas; Riley, Daniel P; van Deventer, Jannie S J

2010-04-07

Understanding the atomic structure of complex metastable (including glassy) materials is of great importance in research and industry, however, such materials resist solution by most standard techniques. Here, a novel technique combining thermodynamics and local structure is presented to solve the structure of the metastable aluminosilicate material metakaolin (calcined kaolinite) without the use of chemical constraints. The structure is elucidated by iterating between least-squares real-space refinement using neutron pair distribution function data, and geometry optimisation using density functional modelling. The resulting structural representation is both energetically feasible and in excellent agreement with experimental data. This accurate structural representation of metakaolin provides new insight into the local environment of the aluminium atoms, with evidence of the existence of tri-coordinated aluminium. By the availability of this detailed chemically feasible atomic description, without the need to artificially impose constraints during the refinement process, there exists the opportunity to tailor chemical and mechanical processes involving metakaolin and other complex metastable materials at the atomic level to obtain optimal performance at the macro-scale.

Populations and lifetimes in the $v=n-l-1=2$ and 3 metastable cascades of $\\overline{p} He^{+}$ measured by pulsed and continuous antiproton beams

CERN Document Server

Hori, Masaki; Widmann, E; Yamazaki, T; Hayano, R S; Ishikawa, T; Torie, H A; Von Egidy, T; Hartmann, F; Ketzer, B; Maierl, C; Pohl, R; Kumakura, M; Morita, N; Horváth, D; Sugai, I

2004-01-01

Using the laser spectroscopy, the time evolution of the state population in the v equivalent n-l=2 and 3 metastable cascades of antiprotonic helium atoms were studied. The effects of the collision between antiprotonic helium and the ordinary helium atoms on the atomic cascade were also analyzed. The measurements were done using the pulsed and continuous types of antiproton beams supplied by the Low Energy Antiproton Ring. The studies revealed five phases in the life history of the metastable antiprotonic helium. (Edited abstract) 71 Refs.

Metastability-exchange optical pumping of 3He for neutron polarizers

International Nuclear Information System (INIS)

Gentile, T.R.; Thompson, A.K.; Snow, W.M.

1995-01-01

Research is underway at NIST and IU to develop neutron polarizers that are based on polarized 3 He. Such polarizers rely on the strong spin dependence of the cross section for neutron capture by polarized 3 He. Two methods can produce the high density of polarized 3 He gas (10 19 -10 20 cm -3 ) required for an effective neutron polarizer: spin-exchange optical pumping, which is performed directly at high pressure (1-10 bar), and metastability-exchange optical pumping, in which the gas is polarized at low pressure (1 mbar) and then compressed. While we are pursuing both methods, progress in the metastable method will be discussed. The features of the metastable method are the high rate at which the gas can be polarized and the inherent separation of the optical pumping and target cells. In a landmark achievement, researchers at the Univ. of Mainz have developed a piston compressor that can fill a 130 cm 3 cell to a pressure of 7 bar of 45% polarized 3 He gas in 2 hours. We plan to develop a compressor and test it at the NIST Cold Neutron Research Facility. We have constructed a metastable-pumping apparatus at NIST and have obtained 76% polarization with a pumping rate of 1.2 x 10 18 atoms/sec in a 0.4 mbar, 270 cm 3 cell

XeBr exciplex laser

International Nuclear Information System (INIS)

Searles, S.K.

1976-01-01

Laser emission from the recently discovered XeBr exciplex laser was investigated as a function of the partial pressures of Xe and Br 2 . An optical loss process appears to limit high-pressure operation

Molecular dynamic simulation of interaction of low-energy Ar and Xe ions with copper clusters at graphite surface

International Nuclear Information System (INIS)

Kornich, G.V.; Lozovskaya, L.I.; Betts, G.; Zaporozhchenko, V.I.; Faupel, F.

2005-01-01

One conducted molecular and dynamic simulation of sputtering of isolated clusters consisting of 13, 27 and 195 Cu atoms from the (0001) graphite surface by 200 eV energy Ar and Xe ions. It is shown that the factors of reflection of Ar and Xe ions from copper clusters differ from one another insignificantly, though the energy of the reflected Xe ions is essentially lower than that of Ar ions. The values of the factor of cluster sputtering by Xe ions are higher in contrast to sputtering by Ar ions. One identified two mechanisms of cluster sputtering resulting in the maximum of sputtering intensity at the polar angles near the normal one, and in periodicity of maximums within the azimuth distributions of sputtering intensity with 60 deg period [ru

Atomic probes of surface structure and dynamics

International Nuclear Information System (INIS)

Heller, E.J.; Jonsson, H.

1992-01-01

The following were studied: New semiclassical method for scattering calculations, He atom scattering from defective Pt surfaces, He atom scattering from Xe overlayers, thermal dissociation of H 2 on Cu(110), spin flip scattering of atoms from surfaces, and Car-Parrinello simulations of surface processes

Simple and efficient method of spin-polarizing a metastable helium beam by diode laser optical pumping

International Nuclear Information System (INIS)

Granitza, B.; Salvietti, M.; Torello, E.; Mattera, L.; Sasso, A.

1995-01-01

Diode laser optical pumping to produce a highly spin-polarized metastable He beam to be used in a spin-polarized metastable atom deexcitation spectroscopy experiment on magnetized surfaces is described. Efficient pumping of the beam is performed by means of an SDL-6702 distributed Bragg reflector diode laser which yields 50 mW of output power in a single longitudinal mode at 1083 nm, the resonance wavelength for the 2 3 S→2 3 P 0,1,2 (D 0 , D 1 , and D 2 ) transitions of He*. The light is circularly polarized by a quarter-wave plate, allowing easy change of the sense of atomic polarization. The laser frequency can be locked to the atomic transition for several hours by phase-sensitive detection of the saturated absorption signal in a He discharge cell. Any of the three transitions of the triplet system can be pumped with the laser but the maximum level of atomic polarization of 98.5% is found pumping the D 2 line. copyright 1995 American Institute of Physics

Atomic collisions related to atomic laser isotope separation

International Nuclear Information System (INIS)

Shibata, Takemasa

1995-01-01

Atomic collisions are important in various places in atomic vapor laser isotope separation (AVLIS). At a vaporization zone, many atomic collisions due to high density have influence on the atomic beam characteristics such as velocity distribution and metastable states' populations at a separation zone. In the separation zone, a symmetric charge transfer between the produced ions and the neutral atoms may degrade selectivity. We have measured atomic excitation temperatures of atomic beams and symmetric charge transfer cross sections for gadolinium and neodymium. Gadolinium and neodymium are both lanthanides. Nevertheless, results for gadolinium and neodymium are very different. The gadolinium atom has one 5d electron and neodymium atom has no 5d electron. It is considered that the differences are due to existence of 5d electron. (author)

An ultracold, optically trapped mixture of 87Rb and metastable 4He atoms

NARCIS (Netherlands)

Flores, A.S.; Mishra, H.P.; Vassen, Wim; Knoop, S.

2017-01-01

We report on the realization of an ultracold (<25 μK) mixture of rubidium (87Rb) and metastable triplet helium (4He) in an optical dipole trap. Our scheme involves laser cooling in a dual-species magneto-optical trap, simultaneous MW- and RF-induced forced evaporative cooling in a quadrupole

The role of the Pauli principle in metastability exchange collisions

International Nuclear Information System (INIS)

Pinard, M.; Laloe, F.

1980-01-01

In optical pumping experiments, metastability exchange collisions are used to transfer orientation, alignment, ... between different atomic levels. This article studies the effect of such collisions on the atom internal variables density operator by a method used in a previous publication for spin exchange collisions. The calculations are valid when the nuclei of the two atoms are distinguishable as well as when they are identical particles, wich allows a detailed discussion of nuclear identity effects (apparent magnetic field, etc...). Two cases are successively studied: no depolarization of the electronic angular momentum (He*-He collisions) and partial depolarization (Ne*-Ne collisions for example). The nuclear identity effects should be observable in low temperature optical pumping experiments with noble gases. In an Appendix, another particle identity effect is studied, which can be observed in atomic beam experiments: during the collision of two 3 He atoms, both in the ground state, the spin state of the atoms scattered in a particular direction can be changed by nuclear indistinguishability effects

Atomic physics

International Nuclear Information System (INIS)

Anon.

1976-01-01

Research activities in atomic physics at Lawrence Berkeley Laboratory during 1976 are described. Topics covered include: experiments on stored ions; test for parity violation in neutral weak currents; energy conservation and astrophysics; atomic absorption spectroscopy, atomic and molecular detectors; theoretical studies of quantum electrodynamics and high-z ions; atomic beam magnetic resonance; radiative decay from the 2 3 Po, 2 levels of helium-like argon; quenching of the metastable 2S/sub 1/2/ state of hydrogen-like argon in an external electric field; and lifetime of the 2 3 Po level of helium-like krypton

Spectral Diagnosis on Contribution of Metastable Atoms to Ionization in Hall Effect Thruster%亚稳态原子对霍尔推力器电离影响的光谱诊断

Institute of Scientific and Technical Information of China (English)

颜世林; 宁中喜; 于达仁

2013-01-01

In order to quantitatively evaluate the contribution of metastable atoms in the ionization process in Hall thrusters (HET),and to improve the accuracy of ionization simulation models,we adopted the emissive-spectrum-intensity-ratio method to obtain the Krypton effective ionization-rate in the channel of HET.The experimental results revealed that,by taking the effect of metastable atoms into consideration,compared with that of base atoms,the Krypton effective ionization-rate increased by about 11 ％ and the increase is most within the electron temperature range of 15～20 eV.Hence,it is concluded that Krypton atoms in HET channel have a relatively high effective ionization rate,and the metastable contribution should be considered in HET ionization models.%霍尔推力器(HET)是一种先进的电推进装置,在航天领域有着广泛应用.为了衡量亚稳态原子对于推力器电离过程的影响,提高相应电离计算模拟模型的准确性,应用发射光谱线强度比计算方法来确定HET通道中包含亚稳态原子贡献的氪原子有效电离速率.实验发现,考虑亚稳态院子的贡献后,氪原子有效电离速率相对于未考虑亚稳态贡献的基态原子电离速率高,在15～20 eV的电子温度范围内增加最多,大约11％.计算结果说明亚稳态原子的存在使得HET通道内氪原子具有较高的有效电离速率,所以在HET电离模型中必须引入亚稳态的贡献项.

Metal-atom fluorescence from the quenching of metastable rare gases by metal carbonyls

International Nuclear Information System (INIS)

Hollingsworth, W.E.

1982-11-01

A flowing afterglow apparatus was used to study the metal fluorescence resulting from the quenching of metastable rare-gas states by metal carbonyls. The data from the quenching or argon, neon, and helium by iron and nickel carbonyl agreed well with a restricted degree of freedom model indicating a concerted bond-breaking dissociation

Directional emission of single photons from small atomic samples

DEFF Research Database (Denmark)

Miroshnychenko, Yevhen; V. Poulsen, Uffe; Mølmer, Klaus

2013-01-01

We provide a formalism to describe deterministic emission of single photons with tailored spatial and temporal profiles from a regular array of multi-level atoms. We assume that a single collective excitation is initially shared by all the atoms in a metastable atomic state, and that this state i...... is coupled by a classical laser field to an optically excited state which rapidly decays to the ground atomic state. Our model accounts for the different field polarization components via re-absorption and emission of light by the Zeeman manifold of optically excited states.......We provide a formalism to describe deterministic emission of single photons with tailored spatial and temporal profiles from a regular array of multi-level atoms. We assume that a single collective excitation is initially shared by all the atoms in a metastable atomic state, and that this state...

Cavity Ring-Down Spectroscopy for Gaseous Fission Products Trace Measurements in Sodium Fast Reactors

International Nuclear Information System (INIS)

Jacquet, P.; Pailloux, A.; Doizi, D.; Aoust, G.; Jeannot, J.-P.

2013-06-01

Safety and availability are key issues of the generation IV reactors. Hence, the three radionuclide confinement barriers, including fuel cladding, must stay tight during the reactor operation. During the primary gaseous failure, fission products xenon and krypton are released. Their fast and sensitive detection guarantees the first confinement barrier tightness. In the frame of the French ASTRID project, an optical spectroscopy technique - Cavity Ring Down Spectroscopy (CRDS) - is investigated for the gaseous fission products measurement. A dedicated CRDS set-up is needed to detect the rare gases with a commercial laser. Indeed, the CRDS is coupled to a glow discharge plasma, which generates a population of metastable atoms. The xenon plasma conditions are optimized to 110 Pa and 1.3 W (3 mA). The production efficiency of metastable Xe is then 0.8 %, stable within 0.5% during hours. The metastable number density is proportional to the xenon over argon molar fraction. The spectroscopic parameters of the strong 823.16 nm xenon transition are calculated and/or measured in order to optimize the fit of the experimental spectra and make a quantitative measurement of the metastable xenon. The CRDS is coupled to the discharge cell. The laser intensity inside the cavity is limited by the optical saturation process, resulting from the strong optical pumping of the metastable state. The resulting weak CRDS signal requires a fast and very sensitive photodetector. A 600 ppt xenon molar fraction was measured by CRDS. With the present set-up, the detection limits are estimated from the baseline noise to approximately 20 ppt for each even isotope, 60 ppt for the 131 Xe and 55 ppt for the 129 Xe. This sensitivity matches the specifications required for gaseous leak measurement; approximately 100 ppt for 133 Xe (4 GBq/m 3 ) and 10 ppb for stable isotopes. The odd isotopes are selectively measured, whereas the even isotopes overlap, a spectroscopic feature that applies for stable or

Absorption of femtosecond laser pulses by atomic clusters

International Nuclear Information System (INIS)

Lin Jingquan; Zhang Jie; Li Yingjun; Chen Liming; Lu Tiezheng; Teng Hao

2001-01-01

Energy absorption by Xe, Ar, He atomic clusters are investigated using laser pulses with 5 mJ energy in 150 fs duration. Experimental results show that the size of cluster and laser absorption efficiency are strongly dependent on several factors, such as the working pressure of pulse valve, atomic number Z of the gas. Absorption fraction of Xe clusters is as high as 45% at a laser intensity of 1 x 10 15 W/cm 2 with 20 x 10 5 Pa gas jet backing pressure. Absorption of the atomic clusters is greatly reduced by introducing pre-pulses. Ion energy measurements confirm that the efficient energy deposition results in a plasma with very high ion temperature

Labelling of macromoleculear carbohydrates by means of 'Hot Atom' reactions

International Nuclear Information System (INIS)

Lundqvist, H.; Malmborg, P.

1976-01-01

Radioactive labelling of polysaccharides have been performed using atoms with such high kinetic energy that they can break normally very stable bindings thus permitting labelling by substitution reactions. Such atoms can be produced in nuclear transformations. We have chosen to study the labelling efficiency of 'hot atoms' ( 77 Br, 123 I and 125 I) produced in radioactive decay (β + -decay and E.C.) of noble gas nuclides ( 77 Kr, 123 Xe and 125 Xe) which easily could be brought in close contact with the molecule to be labelled. Substances to be labelled have been starch particles and high molecular weight glycogen. (author)

Isotope separation by laser deflection of an atomic beam

International Nuclear Information System (INIS)

Bernhardt, A.F.

1975-02-01

Separation of isotopes of barium was accomplished by laser deflection of a single isotopic component of an atomic beam. With a tunable narrow linewidth dye laser, small differences in absorption frequency of different barium isotopes on the 6s 2 1 S 0 --6s6p 1 P 1 5536A resonance were exploited to deflect atoms of a single isotopic component of an atomic beam through an angle large enough to physically separate them from the atomic beam. It is shown that the principal limitation on separation efficiency, the fraction of the desired isotopic component which can be separated, is determined by the branching ratio from the excited state into metastable states. The isotopic purity of the separated atoms was measured to be in excess of 0.9, limited only by instrumental uncertainty. To improve the efficiency of separation, a second dye laser was employed to excite atoms which had decayed to the 6s5d metastable state into the 6p5d 1 P 1 state from which they could decay to the ground state and continue to be deflected on the 5535A transition. With the addition of the second laser, separation efficiency of greater than 83 percent was achieved, limited by metastable state accumulation in the 5d 2 1 D 2 state which is accessible from the 6p5d 1 P 1 level. It was found that the decay rate from the 6p5d state into the 5d 2 metastable state was fully 2/3 the decay rate to the ground state, corresponding to an oscillator strength of 0.58. (U.S.)

XENON IN THE PROTOPLANETARY DISK (PPD-Xe)

Energy Technology Data Exchange (ETDEWEB)

Marti, K.; Mathew, K. J., E-mail: kattathu.mathew@srs.gov [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA (United States)

2015-06-20

Relationships among solar system Xe components as observed in the solar wind, in planetary atmospheres, and in meteorites are investigated using isotopic correlations. The term PPD-Xe is used for components inferred to have been present in the molecular cloud material that formed the protoplanetary disk (PPD). The evidence of the lack of simple relationships between terrestrial atmospheric Xe and solar or meteoritic components is confirmed. Xe isotopic correlations indicate a heterogeneous PPD composition with variable mixing ratios of the nucleosynthetic component Xe-HL. Solar Xe represents a bulk PPD component, and the isotopic abundances did not change from the time of incorporation into the interior of Mars through times of regolith implantations to the present.

XENON IN THE PROTOPLANETARY DISK (PPD-Xe)

International Nuclear Information System (INIS)

Marti, K.; Mathew, K. J.

2015-01-01

Relationships among solar system Xe components as observed in the solar wind, in planetary atmospheres, and in meteorites are investigated using isotopic correlations. The term PPD-Xe is used for components inferred to have been present in the molecular cloud material that formed the protoplanetary disk (PPD). The evidence of the lack of simple relationships between terrestrial atmospheric Xe and solar or meteoritic components is confirmed. Xe isotopic correlations indicate a heterogeneous PPD composition with variable mixing ratios of the nucleosynthetic component Xe-HL. Solar Xe represents a bulk PPD component, and the isotopic abundances did not change from the time of incorporation into the interior of Mars through times of regolith implantations to the present

Xenon in the Protoplanetary Disk (PPD-Xe)

Science.gov (United States)

Marti, K.; Mathew, K. J.

2015-06-01

Relationships among solar system Xe components as observed in the solar wind, in planetary atmospheres, and in meteorites are investigated using isotopic correlations. The term PPD-Xe is used for components inferred to have been present in the molecular cloud material that formed the protoplanetary disk (PPD). The evidence of the lack of simple relationships between terrestrial atmospheric Xe and solar or meteoritic components is confirmed. Xe isotopic correlations indicate a heterogeneous PPD composition with variable mixing ratios of the nucleosynthetic component Xe-HL. Solar Xe represents a bulk PPD component, and the isotopic abundances did not change from the time of incorporation into the interior of Mars through times of regolith implantations to the present.

133Xe and 135Xe interference with in vivo low-energy measurement systems

International Nuclear Information System (INIS)

Cohen, N.; Lo Sasso, T.; Lei, W.

1980-01-01

Fission product 133 Xe and 135 Xe are released to the atmosphere during normal reactor operation. With increasing numbers of nuclear power stations there will be an increase in the ambient level of these isotopes. They do not present an appreciable long-term health hazard because of their inert nature and relatively short half-lives. However, their presence in the air of a whole-body counter may interfere significantly with in vivo low-energy photon counting procedures by contributing to the background count-rate in the energy region below 300 keV. This applies particularly to lung and whole-body measurements with dual thin crystal NaI(Tl)-CsI(Tl) scintillation detectors for actinide nuclides. It is important, therefore, that gamma spectroscopists should be aware of the possible presence of 133 Xe and 135 Xe in the air of their whole-body counting facilities, particularly if these are near to reactors and do not have traps for removal of inert gases from their air supplies. (author)

Influence of the chlorine concentration on the radiation efficiency of a XeCl exciplex lamp

Energy Technology Data Exchange (ETDEWEB)

Avtaeva, S. V., E-mail: s_avtaeva@mail.ru [Kyrgyz-Russian Slavic University (Kyrgyzstan); Sosnin, E. A. [Russian Academy of Sciences, Institute of High-Current Electronics, Siberian Branch (Russian Federation); Saghi, B. [Mohamed Boudiaf University of Sciences and Technology, Department of Electronics (Algeria); Panarin, V. A. [Russian Academy of Sciences, Institute of High-Current Electronics, Siberian Branch (Russian Federation); Rahmani, B. [Mohamed Boudiaf University of Sciences and Technology, Department of Electronics (Algeria)

2013-09-15

The influence of the chlorine concentration on the radiation efficiency of coaxial exciplex lamps (excilamps) excited by a dielectric barrier discharge (DBD) in binary Xe-Cl{sub 2} mixtures at pressures of 240–250 Torr is investigated experimentally and theoretically. The experiments were carried out at Cl{sub 2} concentrations in the range of 0.01–1%. The DBD characteristics were calculated in the framework of a one-dimensional hydrodynamic model at Cl{sub 2} concentrations in the range of 0.1–5%. It is found that the radiation intensities of the emission bands of Xe*{sub 2}(172 nm) and XeCl* (308 nm) are comparable when the chlorine concentration in the mixture is in the range of 0.01–0.1%. In this case, in the mixture, the radiation intensity of the Xe*{sub 2} molecule rapidly decreases with increasing Cl{sub 2} concentration and, at a chlorine concentration of ≥0.2%, the radiation of the B → X band of XeCl* molecules with a peak at 308 nm dominates in the discharge radiation. The radiation efficiency of this band reaches its maximum value at chlorine concentrations in the range of 0.4–0.5%. The calculated efficiencies of DBD radiation exceed those obtained experimentally. This is due to limitations of the one-dimensional model, which assumes the discharge to be uniform in the transverse direction, whereas the actual excilamp discharge is highly inhomogeneous. The influence of the chlorine concentration on the properties of the DBD plasma in binary Xe-Cl{sub 2} mixtures is studied numerically. It is shown that an increase in the Cl{sub 2} concentration in the mixture leads to the attachment of electrons to chlorine atoms and a decrease in the electron density and discharge conductivity. As a result, the electric field and the voltage drop across the discharge gap increase, which, in turn, leads to an increase in the average electron energy and the probability of dissociation of Cl{sub 2} molecules and ionization of Xe atoms and Cl{sub 2} molecules

Influence of the chlorine concentration on the radiation efficiency of a XeCl exciplex lamp

International Nuclear Information System (INIS)

Avtaeva, S. V.; Sosnin, E. A.; Saghi, B.; Panarin, V. A.; Rahmani, B.

2013-01-01

The influence of the chlorine concentration on the radiation efficiency of coaxial exciplex lamps (excilamps) excited by a dielectric barrier discharge (DBD) in binary Xe-Cl 2 mixtures at pressures of 240–250 Torr is investigated experimentally and theoretically. The experiments were carried out at Cl 2 concentrations in the range of 0.01–1%. The DBD characteristics were calculated in the framework of a one-dimensional hydrodynamic model at Cl 2 concentrations in the range of 0.1–5%. It is found that the radiation intensities of the emission bands of Xe* 2 (172 nm) and XeCl* (308 nm) are comparable when the chlorine concentration in the mixture is in the range of 0.01–0.1%. In this case, in the mixture, the radiation intensity of the Xe* 2 molecule rapidly decreases with increasing Cl 2 concentration and, at a chlorine concentration of ≥0.2%, the radiation of the B → X band of XeCl* molecules with a peak at 308 nm dominates in the discharge radiation. The radiation efficiency of this band reaches its maximum value at chlorine concentrations in the range of 0.4–0.5%. The calculated efficiencies of DBD radiation exceed those obtained experimentally. This is due to limitations of the one-dimensional model, which assumes the discharge to be uniform in the transverse direction, whereas the actual excilamp discharge is highly inhomogeneous. The influence of the chlorine concentration on the properties of the DBD plasma in binary Xe-Cl 2 mixtures is studied numerically. It is shown that an increase in the Cl 2 concentration in the mixture leads to the attachment of electrons to chlorine atoms and a decrease in the electron density and discharge conductivity. As a result, the electric field and the voltage drop across the discharge gap increase, which, in turn, leads to an increase in the average electron energy and the probability of dissociation of Cl 2 molecules and ionization of Xe atoms and Cl 2 molecules. The total energy deposited in the discharge

Influence of the chlorine concentration on the radiation efficiency of a XeCl exciplex lamp

Science.gov (United States)

Avtaeva, S. V.; Sosnin, E. A.; Saghi, B.; Panarin, V. A.; Rahmani, B.

2013-09-01

The influence of the chlorine concentration on the radiation efficiency of coaxial exciplex lamps (excilamps) excited by a dielectric barrier discharge (DBD) in binary Xe-Cl2 mixtures at pressures of 240-250 Torr is investigated experimentally and theoretically. The experiments were carried out at Cl2 concentrations in the range of 0.01-1%. The DBD characteristics were calculated in the framework of a one-dimensional hydrodynamic model at Cl2 concentrations in the range of 0.1-5%. It is found that the radiation intensities of the emission bands of Xe*2(172 nm) and XeCl* (308 nm) are comparable when the chlorine concentration in the mixture is in the range of 0.01-0.1%. In this case, in the mixture, the radiation intensity of the Xe*2 molecule rapidly decreases with increasing Cl2 concentration and, at a chlorine concentration of ≥0.2%, the radiation of the B → X band of XeCl* molecules with a peak at 308 nm dominates in the discharge radiation. The radiation efficiency of this band reaches its maximum value at chlorine concentrations in the range of 0.4-0.5%. The calculated efficiencies of DBD radiation exceed those obtained experimentally. This is due to limitations of the one-dimensional model, which assumes the discharge to be uniform in the transverse direction, whereas the actual excilamp discharge is highly inhomogeneous. The influence of the chlorine concentration on the properties of the DBD plasma in binary Xe-Cl2 mixtures is studied numerically. It is shown that an increase in the Cl2 concentration in the mixture leads to the attachment of electrons to chlorine atoms and a decrease in the electron density and discharge conductivity. As a result, the electric field and the voltage drop across the discharge gap increase, which, in turn, leads to an increase in the average electron energy and the probability of dissociation of Cl2 molecules and ionization of Xe atoms and Cl2 molecules. The total energy deposited in the discharge rises with increasing

Study on decay of 118Xe and 119Xe by means of mass-separator on-line with a synchrocyclotron

International Nuclear Information System (INIS)

Berlovich, Eh.E.; Batist, L.Kh.; Blinnikov, Yu.S.

1976-01-01

The decay of sup(118, 119)Xe isotopes has been investigated. An experimental device involving a mass-separator operating in line with a synchrocyclotron is briefly outlined. The elements to be investigated were isolated from a proton-irradiated target by the 'on-beam-chemistry' methods and transferred into the mass-separator ion source. The Xe separated ions are transported to detectors in an experimental ha ll. The energies and relative γ ray intensities of 118 Xe → 118 J and of 119 Xe → 119 J decays ar presented. The error of the γ ray energy determination does not exceed 0.6 keV. Obtained are the periods of half-life: for 118 Xe - (3.8+-0.9) min, for 119 Xe - (5.8+-0.3) min. The decay scheme for 119 Xe is made up. The scheme of 119 Xe levels is well inscribed into the general systematics of the J odd isotope levels. On the basis of obtained and known data the spin values are described to the 119 J levels

Metastable He (n=2) - Ne potential interaction calculation

International Nuclear Information System (INIS)

Rahal, H.

1983-10-01

Diabatic potential terms corresponding to He (2 1 S)-Ne and He (2 3 S)-Ne interactions are calculated. These potentials reproduce the experimental results thermal metastable atom elastic scattering on Ne target. A model which reduces the interaction to a one-electron problem is proposed: the He excited electron. Its interaction with the He + center is reproduced by a ''l'' dependent potential model with a 1/2 behaviour at short range. The electron interaction facing the Ne is described by a l-dependent pseudopotential reproducing with accuracy the electron elastic scattering on a Ne atom. The importance of the corrective term related to the Ne polarizations by the electron and the He + ion is showed in this work. In the modelling problems, the accuracy cannot be better than 0.1 MeV [fr

High energy XeBr electric discharge laser

Science.gov (United States)

Sze, Robert C.; Scott, Peter B.

1981-01-01

A high energy XeBr laser for producing coherent radiation at 282 nm. The XeBr laser utilizes an electric discharge as the excitation source to minimize formation of molecular ions thereby minimizing absorption of laser radiation by the active medium. Additionally, HBr is used as the halogen donor which undergoes harpooning reactions with Xe.sub.M * to form XeBr*.

Experimental confirmation of photon-induced spin-flip transitions in helium via triplet metastable yield spectra

International Nuclear Information System (INIS)

Rubensson, Jan-Erik; Moise, Angelica; Richter, Robert; Mihelic, Andrej; Bucar, Klemen; Zitnik, Matjaz

2010-01-01

Doubly excited states below the N=2 ionization threshold are populated by exciting helium atoms in a supersonic beam with monochromatized synchrotron radiation. The fluorescence decay of these states triggers a radiative cascade back to the ground state with large probability to populate long lived singlet and triplet helium metastable states. The yield of metastables is measured using a multichannel plate detector after the beam has passed a singlet-quenching discharge lamp. The variation of the yield observed with the lamp switched on or off is related to the triplet-singlet mixing of the doubly excited states.

Non-resonant two and three-photon ionization of the singlet and triplet metastable helium atoms of an atomic jet

International Nuclear Information System (INIS)

Mathieu, Bernard.

1978-01-01

The three-photon ionization cross-section of the helium metastables He(2 1 S) and He(2 3 S) is determined by means of the linearly polarized radiation of a pulsed ruby laser with an emission wavelength equal to 6946.4 A at 19 0 C. Two-photon ionization, obtained by doubling the laser beam frequency, is also studied [fr

Controlling interactions between highly magnetic atoms with Feshbach resonances.

Science.gov (United States)

Kotochigova, Svetlana

2014-09-01

This paper reviews current experimental and theoretical progress in the study of dipolar quantum gases of ground and meta-stable atoms with a large magnetic moment. We emphasize the anisotropic nature of Feshbach resonances due to coupling to fast-rotating resonant molecular states in ultracold s-wave collisions between magnetic atoms in external magnetic fields. The dramatic differences in the distribution of resonances of magnetic (7)S3 chromium and magnetic lanthanide atoms with a submerged 4f shell and non-zero electron angular momentum is analyzed. We focus on dysprosium and erbium as important experimental advances have been recently made to cool and create quantum-degenerate gases for these atoms. Finally, we describe progress in locating resonances in collisions of meta-stable magnetic atoms in electronic P-states with ground-state atoms, where an interplay between collisional anisotropies and spin-orbit coupling exists.

Co thin film with metastable bcc structure formed on GaAs(111 substrate

Directory of Open Access Journals (Sweden)

Minakawa Shigeyuki

2014-07-01

Full Text Available Co thin films are prepared on GaAs(111 substrates at temperatures ranging from room temperature to 600 ºC by radio-frequency magnetron sputtering. The growth behavior and the detailed resulting film structure are investigated by in-situ reflection high-energy electron diffraction and X-ray diffraction. In early stages of film growth at temperatures lower than 200 ºC, Co crystals with metastable A2 (bcc structure are formed, where the crystal structure is stabilized through hetero-epitaxial growth. With increasing the film thickness beyond 2 nm, the metastable structure starts to transform into more stable A1 (fcc structure through atomic displacements parallel to the A2{110} close-packed planes. The crystallographic orientation relationship between the A2 and the transformed A1 crystals is A1{111} || A2{110}. When the substrate temperature is higher than 400 ºC, Ga atoms of substrate diffuse into the Co films and a Co-Ga alloy with bcc-based ordered structure of B2 is formed.

Analysis of 125Xe electron-photon coincidence decay

International Nuclear Information System (INIS)

Klingberg, F.J.; Biegalski, S.R.

2016-01-01

As part of the verification component of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), environmental gas samples originating from nuclear fission are analyzed for the presence of 131m Xe, 133m Xe, 133 Xe, and 135 Xe. In this work, the non-traditional radioxenon isotope 125 Xe was investigated. The isotope was produced as an isotopically pure sample via neutron activation of 124 Xe at the University of Texas at Austin Nuclear Engineering Teaching Lab's TRIGA MARK II Reactor. The sample was then measured using a HPGe detector as well as an ARSA-style b-c coincidence detector. Potential sources and sensitivities for production of 125 Xe are also considered for relevance to the CTBT verification mission. (author)

Charge transfer reactions in Xe plasma expansion

International Nuclear Information System (INIS)

Jiao, C. Q.; Garscadden, A.; Ganguly, B. N.

2007-01-01

Charge transfer reactions of fast Xe ions with hydrocarbons including methane (CH 4 ), ethene (C 2 H 4 ), and propane (C 3 H 8 ) are studied by adding these hydrocarbon gases into a cross flowing Xe plasma expansion. Branching ratios and relative reaction rates for the charge transfers of fast Xe + with each of the three hydrocarbon gases are measured under different rf powers of the inductively coupled Xe discharge. For CH 4 /Xe system, we find that fast Xe + reacts readily with CH 4 generating CH 4 + and CH 3 + in a ratio of 1:0.56, with an estimated rate coefficient of (2.3±0.3)x10 -10 cm 3 /s at 75 W rf power which slowly increases to (2.9±0.3)x10 -10 cm 3 /s at 250 W (error bars reflect only the uncertainties due to the unknown extent of the ion recombination that follows the charge transfer reaction). These observed charge transfer reactions are made possible by the kinetically excited Xe ions produced by free expansion of the plasma. For the C 2 H 4 /Xe system product ions C 2 H 4 + and C 2 H 2 + are observed, and for C 3 H 8 /Xe, C 2 H 4 + and C 2 H 5 + and minor product ions including C 2 H 2 + and C 3 H 7 + are observed

Biological Studies with Laser-Polarized ^129Xe

Science.gov (United States)

Tseng, C. H.; Oteiza, E. R.; Wong, G. A.; Walsworth, R. L.; Albert, M. S.; Nascimben, L.; Peled, S.; Sakai, K.; Jolesz, F. A.

1996-05-01

We have studied several biological systems using laser-polarized ^129Xe. In certain tissues magnetic resonance imaging (MRI) using inhaled laser-polarized noble gases may provide images superior to those from conventional proton MRI. High resolution laser-polarized ^3He images of air spaces in the human lung were recently obtained by the Princeton/Duke group. However, ^3He is not very soluble in tissue. Therefore, we are using laser polarized ^129Xe (tissue-soluble), with the long term goal of biomedical functional imaging. We have investigated multi-echo and multi-excitation magnetic resonance detection schemes to exploit the highly non-thermal ^129Xe magnetization produced by the laser polarization technique. We have inhalated live rats with laser-polarized ^129Xe gas and measured three distinct ^129Xe tissue resonances that last 20 to 40 sec. As a demonstration, we obtained a laser polarized ^129Xe image of the human oral cavity. Currently we are measuring the polarization lifetime of ^129Xe dissolved in human blood, the biological transporting medium. These studies and other recent developments will be reported.

Emission characteristics of Xe-RbBr plasma

Science.gov (United States)

Heneral, A. A.; Avtaeva, S. V.

2017-12-01

The luminescence spectra of the longitudinal pulsed-periodic discharge in Xe-RbBr gas-vapour mixtures at low pressures are experimentally studied. Conditions for obtaining strong UV radiation of XeBr* exiplex molecules in the spectral range of 200-425 nm are found. The greatest output of the XeBr* UV radiation is provided at temperature of the gas-discharge tube walls of ~1000 K. The maximum UV emission power of the whole plasma volume is 4.8 W. Formation of XeBr* exciplex molecules in the pulsed-periodic discharge in Xe-RbBr gas-vapour mixtures at low pressures is discussed.

Results on the role of metastable Ar atoms in a 9-MHz high-power atmospheric ICP by using emission/absorption spectrometry

International Nuclear Information System (INIS)

Gunter, W.; Zeeman, P.B.; Visser, K.

1984-01-01

An investigation into the role of overpopulations of metastable argon levels as agents for causing non-local thermal equilibrium (LTE) in an inductively coupled plasma source (ICP), was carried out. Four argon transitions in the near infrared region were monitored through absorption measurements at two different observation heights in a 9-MHz high-power ICP. The lower states of the four transitions consist of two metastable (11.55 and 11.72 eV) and two radiating (11.62 and 11.83 eV) levels. Comparison of measured metastable level to radiating level absorbance ratios with calculated population ratios gave an indication whether overpopulations of certain levels existed. Results indicate no overpopulation of metastable states with respect to radiating states, arguing against their role as non-LTE mechanism agents. This conclusion is, however, preliminary, since the calculation of absolute population densities from absorbance measurements must still be carried out

Transition probabilities for atoms

International Nuclear Information System (INIS)

Kim, Y.K.

1980-01-01

Current status of advanced theoretical methods for transition probabilities for atoms and ions is discussed. An experiment on the f values of the resonance transitions of the Kr and Xe isoelectronic sequences is suggested as a test for the theoretical methods

Electron-Impact Ionization Cross Sections of H, He, N, O, Ar, Xe, Au, Pb Atoms and Their Ions in the Electron Energy Range from the Threshold up to 200 keV

CERN Document Server

Povyshev, V M; Shevelko, V P; Shirkov, G D; Vasina, E G; Vatulin, V V

2001-01-01

Single electron-impact ionization cross sections of H, He, N, O, Ar, Xe, Au, Pb atoms and their positive ions (i.e. all ionization stages) are presented in the electron energy range from the threshold up to 200 keV. The data-set for the cross sections has been created on the basis of available experimental data and calculations performed by the computer code ATOM. Consistent data for the ionization cross sections have been fitted by seven parameters using the LSM method. The accuracy of the calculated data presented is within a factor of 2 that in many cases is sufficient to solve the plasma kinetics problems. Contributions from excitation-autoionization and resonant-ionization processes as well as ionization of atoms and ions are not considered here. The results of the numerical calculations are compared with the well-known Lotz formulae for ionization of neutral atoms and positive ions. The material is illustrated by figures and includes tables of ionization cross sections, binding energies and fitting para...

High-power frequency-stabilized laser for laser cooling of metastable helium at 389 nm

NARCIS (Netherlands)

Koelemeij, J.C.J.; Hogervorst, W.; Vassen, W.

2005-01-01

A high-power, frequency-stabilized laser for cooling of metastable helium atoms using the 2 S13 →3 P23 transition at 389 nm has been developed. The 389 nm light is generated by frequency doubling of a titanium:sapphire laser in an external enhancement cavity containing a lithium-triborate nonlinear

Performance assessment of a new laser system for efficient spin exchange optical pumping in a spin maser measurement of 129Xe EDM

International Nuclear Information System (INIS)

Funayama, C.; Furukawa, T.; Sato, T.; Ichikawa, Y.; Ohtomo, Y.; Sakamoto, Y.; Kojima, S.; Suzuki, T.; Hirao, C.; Chikamori, M.; Hikota, E.; Tsuchiya, M.; Yoshimi, A.; Bidinosti, C. P.; Ino, T.; Ueno, H.; Matsuo, Y.; Fukuyama, T.; Asahi, K.

2015-01-01

We demonstrate spin-exchange optical pumping of 129 Xe atoms with our newly made laser system. The new laser system was prepared to provide higher laser power required for the stable operation of spin maser oscillations in the 129 Xe EDM experiment. We studied the optimum cell temperature and pumping laser power to improve the degree of 129 Xe spin polarization. The best performance was achieved at the cell temperature of 100 ∘ C with the presently available laser power of 1 W. The results show that a more intense laser is required for further improvement of the spin polarization at higher cell temperatures in our experiment

Two new Np--Ga phases: α-NpGa2 and metastable m-NpGa2

International Nuclear Information System (INIS)

Giessen, B.C.; Elliott, R.O.

1976-01-01

Following an earlier study of metastable Np-rich Np--Ga alloys, rapidly quenched Np--Ga alloys with 63 to 80 at. pct. Ga were prepared and studied. Two new NpGa 2 phases, both with an AlB 2 type structure, were found: α-NpGa 2 , with a = 4.246A, c = 4.060A, c/a = 0.956, and m-NpGa 2 , with a = 4.412A, c = 3.642A, c/a = 0.825. While m-NpGa 2 was observed only in very fast quenched (splat cooled) samples and appears to be metastable, α-NpGa 2 is probably an equilibrium phase. In a splat cooled alloy with 75 at. pct. Ga, another, unidentified, metastable phase was observed. Crystal chemical discussions of atomic volumes, interatomic distances and axial ratios are given; the volume difference between the two forms of NpGa 2 is correlated with a valence change of Np

Exotic species with explicit noble metal-noble gas-noble metal linkages.

Science.gov (United States)

Moreno, Norberto; Restrepo, Albeiro; Hadad, C Z

2018-02-14

We present a study of the isoelectronic Pt 2 Ng 2 F 4 and [Au 2 Ng 2 F 4 ] 2+ species with noble gas atoms (Ng = Kr, Xe, Rn) acting as links bridging the two noble metal atoms. The stability of the species is investigated using several thermodynamic, kinetic and reactivity indicators. The results are compared against [AuXe 4 ] 2+ , which is thermodynamically unstable in the gas phase but is stabilized in the solid state to the point that it has been experimentally detected as [AuXe 4 ](Sb 2 F 11 ) 2 (S. Seidel and K. Seppelt, Science, 2000, 290, 117-118). Our results indicate that improving upon [AuXe 4 ] 2+ , these exotic combinations between the a priori non-reactive noble metals and noble gases lead to metastable species, and, therefore, they have the possibility of existing in the solid state under adequate conditions. Our calculations include accurate energies and geometries at both the CCSD/SDDALL and MP2/SDDALL levels. We offer a detailed description of the nature of the bonding interactions using orbital and density-based analyses. The computational evidence suggests partially covalent and ionic interactions as the stabilization factors.

Charged particle suppression in Pb+Pb and Xe+Xe collisions measured with the ATLAS detector

CERN Document Server

Balek, Petr; The ATLAS collaboration

2018-01-01

The measurement of charge particle production in heavy ion collisions, when compared with pp data, provides insight into the properties of the hot and dense quark-gluon plasma. The ATLAS detector at the LHC recorded 0.49 nb$^{−1}$ of Pb+Pb collisions and 4.2 pb$^{−1}$ of pp collisions, both at the center-of-mass energy $\\sqrt{s}=\\sqrt{s_{NN}}=5.02$ TeV. Recently, ATLAS also recorded 3 $\\mu$b$^{−1}$ of Xe+Xe collisions at $\\sqrt{s_{NN}}=5.44$ TeV, which offers a new opportunity to study the system size dependence of the parton energy loss. The large acceptance of the ATLAS detector allows measurements of charged hadron spectra in a wide range of both pseudorapidity and transverse momentum, differentially in collision centrality. The charged hadron spectra measured in Pb+Pb and Xe+Xe collisions are compared to the analogous spectra measured in pp collisions, and the resulting nuclear modification factors $R_{AA}$ are studied.

Bibliography of electron and photon cross sections with atoms and molecules published in the 20th century. Xenon

International Nuclear Information System (INIS)

Hayashi, Makoto

2003-09-01

A bibliographies of original and review reports of experiments or theories of electron and photon cross sections and also electron swarm data are presented for atomic or molecular species with specified targets. These works covered 17 atoms and 51 molecules. The present bibliography is only for xenon (Xe). About 1180 papers were compiled. A comprehensive author index is included. The bibliography covers the period 1921 through 2000 for Xe. Finally, author's recommended Xe electron collision cross section set is given by number tables. (author)

Pairwise additivity in the nuclear magnetic resonance interactions of atomic xenon.

Science.gov (United States)

Hanni, Matti; Lantto, Perttu; Vaara, Juha

2009-04-14

Nuclear magnetic resonance (NMR) of atomic (129/131)Xe is used as a versatile probe of the structure and dynamics of various host materials, due to the sensitivity of the Xe NMR parameters to intermolecular interactions. The principles governing this sensitivity can be investigated using the prototypic system of interacting Xe atoms. In the pairwise additive approximation (PAA), the binary NMR chemical shift, nuclear quadrupole coupling (NQC), and spin-rotation (SR) curves for the xenon dimer are utilized for fast and efficient evaluation of the corresponding NMR tensors in small xenon clusters Xe(n) (n = 2-12). If accurate, the preparametrized PAA enables the analysis of the NMR properties of xenon clusters, condensed xenon phases, and xenon gas without having to resort to electronic structure calculations of instantaneous configurations for n > 2. The binary parameters for Xe(2) at different internuclear distances were obtained at the nonrelativistic Hartree-Fock level of theory. Quantum-chemical (QC) calculations at the corresponding level were used to obtain the NMR parameters of the Xe(n) (n = 2-12) clusters at the equilibrium geometries. Comparison of PAA and QC data indicates that the direct use of the binary property curves of Xe(2) can be expected to be well-suited for the analysis of Xe NMR in the gaseous phase dominated by binary collisions. For use in condensed phases where many-body effects should be considered, effective binary property functions were fitted using the principal components of QC tensors from Xe(n) clusters. Particularly, the chemical shift in Xe(n) is strikingly well-described by the effective PAA. The coordination number Z of the Xe site is found to be the most important factor determining the chemical shift, with the largest shifts being found for high-symmetry sites with the largest Z. This is rationalized in terms of the density of virtual electronic states available for response to magnetic perturbations.

All-optical atom trap trace analysis for rare krypton isotopes

Energy Technology Data Exchange (ETDEWEB)

Woelk, Pablo; Kohler, Markus; Sieveke, Carsten; Hebel, Simon; Sahling, Peter [Carl Friedrich von Weizsaecker Centre for Science and Peace Research, University of Hamburg (Germany); Becker, Christoph; Sengstock, Klaus [Institut fuer Laser-Physik, University of Hamburg (Germany)

2016-07-01

The isotope Krypton-85 is an excellent indicator for the detection of nuclear reprocessing activities. However, for the analysis of atmospheric air samples, sensitive measuring methods down to the single atom level are required because of the small concentrations. Furthermore, for a practical and effective detection of clandestine reprocessing, small sample sizes and a high sample throughput rate are desirable. Established methods using Atom Trap Trace Analysis (ATTA) allow high sensitivity but have a limited throughput of about 200 samples per year, since the vacuum chambers have to be flushed for several hours after each measurement to avoid cross contamination due to the RF-driven excitation of metastable states. Here we present an enhanced ATTA apparatus, which in contrast to the established methods, produces metastable Kr all-optically. This avoids cross contamination, therefore allowing a much higher throughput rate. The apparatus is based on a self-made VUV-lamp and a 2D-3D magneto-optical trap setup. In the 2D trap metastable krypton is produced and a beam of atoms is formed by Doppler-cooling simultaneously.

High densities and optical collisions in a two-colour magneto-optical trap for metastable helium

NARCIS (Netherlands)

Koelemeij, J.C.J.; Tychkov, A.; Jeltes, T.; Hogervorst, W.; Vassen, W.

2004-01-01

We have studied a cloud of cold metastable helium (He*) atoms interacting with near-resonant light at 1083 nm and 389 nm. The 1083 nm light allows for efficient loading of a large magneto-optical trap (MOT) and the 389 nm light is subsequently used to increase the density and reduce the temperature

Spatial distributions of Cu polycrystal sputtered atoms

International Nuclear Information System (INIS)

Abgaryan, V.K.; Semenov, A.A.; Shkarban, I.I.

2004-01-01

The results of the experimental determination of the Cu atoms spatial distribution, sputtered from the polycrystalline copper target, irradiated by the Xe + ions with the energy of 300 eV, are presented. The spatial distributions of the sputtered particles, calculated through the quasistable-dynamic model of the cascade modeling (CAMO) are presented also for the case of the polycrystalline copper irradiation by the Ar + and Xe + ions with the energy of 300-1000 eV [ru

Negligible fractionation of Kr and Xe isotopes by molecular diffusion in water

Science.gov (United States)

Tyroller, Lina; Brennwald, Matthias S.; Busemann, Henner; Maden, Colin; Baur, Heinrich; Kipfer, Rolf

2018-06-01

Molecular diffusion is a key transport process for noble gases in water. Such diffusive transport is often thought to cause a mass-dependent fractionation of noble gas isotopes that is inversely proportional to the square root of the ratio of their atomic mass, referred to as the square root relation. Previous studies, challenged the commonly held assumption that the square root relation adequately describes the behaviour of noble gas isotopes diffusing through water. However, the effect of diffusion on noble gas isotopes has only been determined experimentally for He, Ne and Ar to date, whereas the extent of fractionation of Kr and Xe has not been measured. In the present study the fractionation of Kr and Xe isotopes diffusing through water immobilised by adding agar was quantified through measuring the respective isotope ratio after diffusing through the immobilised water. No fractionation of Kr and Xe isotopes was observed, even using high-precision noble gas analytics. These results complement our current understanding on isotopic fractionation of noble gases diffusing through water. Therefore this complete data set builds a robust basis to describe molecular diffusion of noble gases in water in a physical sound manner which is fundamental to assess the physical aspects of gas dynamics in aquatic systems.

Inclusive J/$\\psi$ production in Xe-Xe collisions at $\\sqrt{s_{NN}}$ = 5.44 TeV

CERN Document Server

Acharya, Shreyasi; The ALICE collaboration; Adamova, Dagmar; Adolfsson, Jonatan; Aggarwal, Madan Mohan; Aglieri Rinella, Gianluca; Agnello, Michelangelo; Agrawal, Neelima; Ahammed, Zubayer; Ahn, Sang Un; Aiola, Salvatore; Akindinov, Alexander; Al-turany, Mohammad; Alam, Sk Noor; Silva De Albuquerque, Danilo; Aleksandrov, Dmitry; Alessandro, Bruno; Alfaro Molina, Jose Ruben; Ali, Yasir; Alici, Andrea; Alkin, Anton; Alme, Johan; Alt, Torsten; Altenkamper, Lucas; Altsybeev, Igor; Anaam, Mustafa Naji; Andrei, Cristian; Andreou, Dimitra; Andrews, Harry Arthur; Andronic, Anton; Angeletti, Massimo; Anguelov, Venelin; Anson, Christopher Daniel; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Anwar, Rafay; Apadula, Nicole; Aphecetche, Laurent Bernard; Appelshaeuser, Harald; Arcelli, Silvia; Arnaldi, Roberta; Arnold, Oliver Werner; Arsene, Ionut Cristian; Arslandok, Mesut; Audurier, Benjamin; Augustinus, Andre; Averbeck, Ralf Peter; Azmi, Mohd Danish; Badala, Angela; Baek, Yong Wook; Bagnasco, Stefano; Bailhache, Raphaelle Marie; Bala, Renu; Baldisseri, Alberto; Ball, Markus; Baral, Rama Chandra; Barbano, Anastasia Maria; Barbera, Roberto; Barile, Francesco; Barioglio, Luca; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Ramillien Barret, Valerie; Bartalini, Paolo; Barth, Klaus; Bartsch, Esther; Bastid, Nicole; Basu, Sumit; Batigne, Guillaume; Batyunya, Boris; Batzing, Paul Christoph; Bazo Alba, Jose Luis; Bearden, Ian Gardner; Beck, Hans; Bedda, Cristina; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bello Martinez, Hector; Bellwied, Rene; Espinoza Beltran, Lucina Gabriela; Belyaev, Vladimir; Bencedi, Gyula; Beole, Stefania; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bertens, Redmer Alexander; Berzano, Dario; Betev, Latchezar; Bhaduri, Partha Pratim; Bhasin, Anju; Bhat, Inayat Rasool; Bhatt, Himani; Bhattacharjee, Buddhadeb; Bhom, Jihyun; Bianchi, Antonio; Bianchi, Livio; Bianchi, Nicola; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Biro, Gabor; Biswas, Rathijit; Biswas, Saikat; Blair, Justin Thomas; Blau, Dmitry; Blume, Christoph; Boca, Gianluigi; Bock, Friederike; Bogdanov, Alexey; Boldizsar, Laszlo; Bombara, Marek; Bonomi, Germano; Bonora, Matthias; Borel, Herve; Borissov, Alexander; Borri, Marcello; Botta, Elena; Bourjau, Christian; Bratrud, Lars; Braun-munzinger, Peter; Bregant, Marco; Broker, Theo Alexander; Broz, Michal; Brucken, Erik Jens; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Buhler, Paul; Buncic, Predrag; Busch, Oliver; Buthelezi, Edith Zinhle; Bashir Butt, Jamila; Buxton, Jesse Thomas; Cabala, Jan; Caffarri, Davide; Caines, Helen Louise; Caliva, Alberto; Calvo Villar, Ernesto; Soto Camacho, Rabi; Camerini, Paolo; Capon, Aaron Allan; Carena, Francesco; Carena, Wisla; Carnesecchi, Francesca; Castillo Castellanos, Javier Ernesto; Castro, Andrew John; Casula, Ester Anna Rita; Ceballos Sanchez, Cesar; Chandra, Sinjini; Chang, Beomsu; Chang, Wan; Chapeland, Sylvain; Chartier, Marielle; Chattopadhyay, Subhasis; Chattopadhyay, Sukalyan; Chauvin, Alex; Cheshkov, Cvetan Valeriev; Cheynis, Brigitte; Chibante Barroso, Vasco Miguel; Dobrigkeit Chinellato, David; Cho, Soyeon; Chochula, Peter; Chowdhury, Tasnuva; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Colamaria, Fabio Filippo; Colella, Domenico; Collu, Alberto; Colocci, Manuel; Concas, Matteo; Conesa Balbastre, Gustavo; Conesa Del Valle, Zaida; Contreras Nuno, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortese, Pietro; Cosentino, Mauro Rogerio; Costa, Filippo; Costanza, Susanna; Crkovska, Jana; Crochet, Philippe; Cuautle Flores, Eleazar; Cunqueiro Mendez, Leticia; Dahms, Torsten; Dainese, Andrea; Dani, Sanskruti; Danisch, Meike Charlotte; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Supriya; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; De Caro, Annalisa; De Cataldo, Giacinto; De Conti, Camila; De Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; De Marco, Nora; De Pasquale, Salvatore; Derradi De Souza, Rafael; Franz Degenhardt, Hermann; Deisting, Alexander; Deloff, Andrzej; Delsanto, Silvia; Deplano, Caterina; Dhankher, Preeti; Di Bari, Domenico; Di Mauro, Antonio; Di Ruzza, Benedetto; Arteche Diaz, Raul; Dietel, Thomas; Dillenseger, Pascal; Ding, Yanchun; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Domenicis Gimenez, Diogenes; Donigus, Benjamin; Dordic, Olja; Van Doremalen, Lennart Vincent; Dubey, Anand Kumar; Dubla, Andrea; Ducroux, Laurent; Dudi, Sandeep; Duggal, Ashpreet Kaur; Dukhishyam, Mallick; Dupieux, Pascal; Ehlers Iii, Raymond James; Elia, Domenico; Endress, Eric; Engel, Heiko; Epple, Eliane; Erazmus, Barbara Ewa; Erhardt, Filip; Ersdal, Magnus Rentsch; Espagnon, Bruno; Eulisse, Giulio; Eum, Jongsik; Evans, David; Evdokimov, Sergey; Fabbietti, Laura; Faggin, Mattia; Faivre, Julien; Fantoni, Alessandra; Fasel, Markus; Feldkamp, Linus; Feliciello, Alessandro; Feofilov, Grigorii; Fernandez Tellez, Arturo; Ferretti, Alessandro; Festanti, Andrea; Feuillard, Victor Jose Gaston; Figiel, Jan; Araujo Silva Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fiorenza, Gabriele; Flor, Fernando; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Francescon, Andrea; Francisco, Audrey; Frankenfeld, Ulrich Michael; Fronze, Gabriele Gaetano; Fuchs, Ulrich; Furget, Christophe; Furs, Artur; Fusco Girard, Mario; Gaardhoeje, Jens Joergen; Gagliardi, Martino; Gago Medina, Alberto Martin; Gajdosova, Katarina; Gallio, Mauro; Duarte Galvan, Carlos; Ganoti, Paraskevi; Garabatos Cuadrado, Jose; Garcia-solis, Edmundo Javier; Garg, Kunal; Gargiulo, Corrado; Gasik, Piotr Jan; Gauger, Erin Frances; De Leone Gay, Maria Beatriz; Germain, Marie; Ghosh, Jhuma; Ghosh, Premomoy; Ghosh, Sanjay Kumar; Gianotti, Paola; Giubellino, Paolo; Giubilato, Piero; Glassel, Peter; Gomez Coral, Diego Mauricio; Gomez Ramirez, Andres; Gonzalez, Victor; Gonzalez Zamora, Pedro; Gorbunov, Sergey; Gorlich, Lidia Maria; Gotovac, Sven; Grabski, Varlen; Graczykowski, Lukasz Kamil; Graham, Katie Leanne; Greiner, Leo Clifford; Grelli, Alessandro; Grigoras, Costin; Grigoryev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Gronefeld, Julius Maximilian; Grosa, Fabrizio; Grosse-oetringhaus, Jan Fiete; Grosso, Raffaele; Guernane, Rachid; Guerzoni, Barbara; Guittiere, Manuel; Gulbrandsen, Kristjan Herlache; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Bautista Guzman, Irais; Haake, Rudiger; Habib, Michael Karim; Hadjidakis, Cynthia Marie; Hamagaki, Hideki; Hamar, Gergoe; Hamid, Mohammed; Hamon, Julien Charles; Hannigan, Ryan; Haque, Md Rihan; Harris, John William; Harton, Austin Vincent; Hassan, Hadi; Hatzifotiadou, Despina; Hayashi, Shinichi; Heckel, Stefan Thomas; Hellbar, Ernst; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Gonzalez Hernandez, Emma; Herrera Corral, Gerardo Antonio; Herrmann, Florian; Hetland, Kristin Fanebust; Hilden, Timo Eero; Hillemanns, Hartmut; Hills, Christopher; Hippolyte, Boris; Hohlweger, Bernhard; Horak, David; Hornung, Sebastian; Hosokawa, Ritsuya; Hota, Jyotishree; Hristov, Peter Zahariev; Huang, Chun-lu; Hughes, Charles; Huhn, Patrick; Humanic, Thomas; Hushnud, Hushnud; Hussain, Nur; Hussain, Tahir; Hutter, Dirk; Hwang, Dae Sung; Iddon, James Philip; Iga Buitron, Sergio Arturo; Ilkaev, Radiy; Inaba, Motoi; Ippolitov, Mikhail; Islam, Md Samsul; Ivanov, Marian; Ivanov, Vladimir; Izucheev, Vladimir; Jacak, Barbara; Jacazio, Nicolo; Jacobs, Peter Martin; Jadhav, Manoj Bhanudas; Jadlovska, Slavka; Jadlovsky, Jan; Jaelani, Syaefudin; Jahnke, Cristiane; Jakubowska, Monika Joanna; Janik, Malgorzata Anna; Jena, Chitrasen; Jercic, Marko; Jevons, Oliver; Jimenez Bustamante, Raul Tonatiuh; Jin, Muqing; Jones, Peter Graham; Jusko, Anton; Kalinak, Peter; Kalweit, Alexander Philipp; Kang, Ju Hwan; Kaplin, Vladimir; Kar, Somnath; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karczmarczyk, Przemyslaw; Karpechev, Evgeny; Kebschull, Udo Wolfgang; Keidel, Ralf; Keijdener, Darius Laurens; Keil, Markus; Ketzer, Bernhard Franz; Khabanova, Zhanna; Khan, Ahsan Mehmood; Khan, Shaista; Khan, Shuaib Ahmad; Khanzadeev, Alexei; Kharlov, Yury; Khatun, Anisa; Khuntia, Arvind; Kielbowicz, Miroslaw Marek; Kileng, Bjarte; Kim, Byungchul; Kim, Daehyeok; Kim, Dong Jo; Kim, Eun Joo; Kim, Hyeonjoong; Kim, Jinsook; Kim, Jiyoung; Kim, Minjung; Kim, Se Yong; Kim, Taejun; Kim, Taesoo; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Klay, Jennifer Lynn; Klein, Carsten; Klein, Jochen; Klein-boesing, Christian; Klewin, Sebastian; Kluge, Alexander; Knichel, Michael Linus; Knospe, Anders Garritt; Kobdaj, Chinorat; Varga-kofarago, Monika; Kohler, Markus Konrad; Kollegger, Thorsten; Kondratyeva, Natalia; Kondratyuk, Evgeny; Konevskikh, Artem; Konyushikhin, Maxim; Kovalenko, Oleksandr; Kovalenko, Vladimir; Kowalski, Marek; Kralik, Ivan; Kravcakova, Adela; Kreis, Lukas; Krivda, Marian; Krizek, Filip; Kruger, Mario; Kryshen, Evgeny; Krzewicki, Mikolaj; Kubera, Andrew Michael; Kucera, Vit; Kuhn, Christian Claude; Kuijer, Paulus Gerardus; Kumar, Jitendra; Kumar, Lokesh; Kumar, Shyam; Kundu, Sourav; Kurashvili, Podist; Kurepin, Alexander; Kurepin, Alexey; Kuryakin, Alexey; Kushpil, Svetlana; Kvapil, Jakub; Kweon, Min Jung; Kwon, Youngil; La Pointe, Sarah Louise; La Rocca, Paola; Lai, Yue Shi; Lakomov, Igor; Langoy, Rune; Lapidus, Kirill; Lara Martinez, Camilo Ernesto; Lardeux, Antoine Xavier; Larionov, Pavel; Laudi, Elisa; Lavicka, Roman; Lea, Ramona; Leardini, Lucia; Lee, Seongjoo; Lehas, Fatiha; Lehner, Sebastian; Lehrbach, Johannes; Lemmon, Roy Crawford; Leon Monzon, Ildefonso; Levai, Peter; Li, Xiaomei; Li, Xing Long; Lien, Jorgen Andre; Lietava, Roman; Lim, Bong-hwi; Lindal, Svein; Lindenstruth, Volker; Lindsay, Scott William; Lippmann, Christian; Lisa, Michael Annan; Litichevskyi, Vladyslav; Liu, Alwina; Ljunggren, Hans Martin; Llope, William; Lodato, Davide Francesco; Loginov, Vitaly; Loizides, Constantinos; Loncar, Petra; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lowe, Andrew John; Luettig, Philipp Johannes; Luhder, Jens Robert; Lunardon, Marcello; Luparello, Grazia; Lupi, Matteo; Maevskaya, Alla; Mager, Magnus; Mahmood, Sohail Musa; Maire, Antonin; Majka, Richard Daniel; Malaev, Mikhail; Malik, Qasim Waheed; Malinina, Liudmila; Mal'kevich, Dmitry; Malzacher, Peter; Mamonov, Alexander; Manko, Vladislav; Manso, Franck; Manzari, Vito; Mao, Yaxian; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Margutti, Jacopo; Marin, Ana Maria; Markert, Christina; Marquard, Marco; Martin, Nicole Alice; Martinengo, Paolo; Martinez, Jacobb Lee; Martinez Hernandez, Mario Ivan; Martinez-garcia, Gines; Martinez Pedreira, Miguel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Massacrier, Laure Marie; Masson, Erwann; Mastroserio, Annalisa; Mathis, Andreas Michael; Toledo Matuoka, Paula Fernanda; Matyja, Adam Tomasz; Mayer, Christoph; Mazzilli, Marianna; Mazzoni, Alessandra Maria; Meddi, Franco; Melikyan, Yuri; Menchaca-rocha, Arturo Alejandro; Meninno, Elisa; Mercado-perez, Jorge; Meres, Michal; Soncco Meza, Carlos; Mhlanga, Sibaliso; Miake, Yasuo; Micheletti, Luca; Mieskolainen, Matti Mikael; Mihaylov, Dimitar Lubomirov; Mikhaylov, Konstantin; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz Czeslaw; Mitra, Jubin; Mitu, Ciprian Mihai; Mohammadi, Naghmeh; Mohanty, Auro Prasad; Mohanty, Bedangadas; Khan, Mohammed Mohisin; Moreira De Godoy, Denise Aparecida; Perez Moreno, Luis Alberto; Moretto, Sandra; Morreale, Astrid; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhlheim, Daniel Michael; Muhuri, Sanjib; Mukherjee, Maitreyee; Mulligan, James Declan; Gameiro Munhoz, Marcelo; Munning, Konstantin; Arratia Munoz, Miguel Ignacio; Munzer, Robert Helmut; Murakami, Hikari; Murray, Sean; Musa, Luciano; Musinsky, Jan; Myers, Corey James; Myrcha, Julian Wojciech; Naik, Bharati; Nair, Rahul; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Narayan, Amrendra; Naru, Muhammad Umair; Nassirpour, Adrian Fereydon; Ferreira Natal Da Luz, Pedro Hugo; Nattrass, Christine; Rosado Navarro, Sebastian; Nayak, Kishora; Nayak, Ranjit; Nayak, Tapan Kumar; Nazarenko, Sergey; Negrao De Oliveira, Renato Aparecido; Nellen, Lukas; Nesbo, Simon Voigt; Neskovic, Gvozden; Ng, Fabian; Nicassio, Maria; Niedziela, Jeremi; Nielsen, Borge Svane; Nikolaev, Sergey; Nikulin, Sergey; Nikulin, Vladimir; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Cabanillas Noris, Juan Carlos; Norman, Jaime; Nyanin, Alexander; Nystrand, Joakim Ingemar; Oh, Hoonjung; Ohlson, Alice Elisabeth; Oleniacz, Janusz; Oliveira Da Silva, Antonio Carlos; Oliver, Michael Henry; Onderwaater, Jacobus; Oppedisano, Chiara; Orava, Risto; Oravec, Matej; Ortiz Velasquez, Antonio; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Pachmayer, Yvonne Chiara; Pacik, Vojtech; Pagano, Davide; Paic, Guy; Palni, Prabhakar; Pan, Jinjin; Pandey, Ashutosh Kumar; Panebianco, Stefano; Papikyan, Vardanush; Pareek, Pooja; Park, Jonghan; Parkkila, Jasper Elias; Parmar, Sonia; Passfeld, Annika; Pathak, Surya Prakash; Patra, Rajendra Nath; Paul, Biswarup; Pei, Hua; Peitzmann, Thomas; Peng, Xinye; Pereira, Luis Gustavo; Pereira Da Costa, Hugo Denis Antonio; Peresunko, Dmitry Yurevich; Perez Lezama, Edgar; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petrovici, Mihai; Petta, Catia; Peretti Pezzi, Rafael; Piano, Stefano; Pikna, Miroslav; Pillot, Philippe; Ozelin De Lima Pimentel, Lais; Pinazza, Ombretta; Pinsky, Lawrence; Pisano, Silvia; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Planinic, Mirko; Pliquett, Fabian; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polishchuk, Boris; Poljak, Nikola; Poonsawat, Wanchaloem; Pop, Amalia; Poppenborg, Hendrik; Porteboeuf, Sarah Julie; Pozdniakov, Valeriy; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puccio, Maximiliano; Punin, Valery; Putschke, Jorn Henning; Raha, Sibaji; Rajput, Sonia; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Rami, Fouad; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Ratza, Viktor; Ravasenga, Ivan; Read, Kenneth Francis; Redlich, Krzysztof; Rehman, Attiq Ur; Reichelt, Patrick Simon; Reidt, Felix; Ren, Xiaowen; Renfordt, Rainer Arno Ernst; Reshetin, Andrey; Revol, Jean-pierre; Reygers, Klaus Johannes; Riabov, Viktor; Richert, Tuva Ora Herenui; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Ristea, Catalin-lucian; Rode, Sudhir Pandurang; Rodriguez Cahuantzi, Mario; Roeed, Ketil; Rogalev, Roman; Rogochaya, Elena; Rohr, David Michael; Roehrich, Dieter; Rokita, Przemyslaw Stefan; Ronchetti, Federico; Dominguez Rosas, Edgar; Roslon, Krystian; Rosnet, Philippe; Rossi, Andrea; Rotondi, Alberto; Roukoutakis, Filimon; Roy, Christelle Sophie; Roy, Pradip Kumar; Vazquez Rueda, Omar; Rui, Rinaldo; Rumyantsev, Boris; Rustamov, Anar; Ryabinkin, Evgeny; Ryabov, Yury; Rybicki, Andrzej; Saarinen, Sampo; Sadhu, Samrangy; Sadovskiy, Sergey; Safarik, Karel; Saha, Sumit Kumar; Sahoo, Baidyanath; Sahoo, Pragati; Sahoo, Raghunath; Sahoo, Sarita; Sahu, Pradip Kumar; Saini, Jogender; Sakai, Shingo; Saleh, Mohammad Ahmad; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sandoval, Andres; Sarkar, Amal; Sarkar, Debojit; Sarkar, Nachiketa; Sarma, Pranjal; Sas, Mike Henry Petrus; Scapparone, Eugenio; Scarlassara, Fernando; Schaefer, Brennan; Scheid, Horst Sebastian; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schmidt, Marten Ole; Schmidt, Martin; Schmidt, Nicolas Vincent; Schukraft, Jurgen; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Sefcik, Michal; Seger, Janet Elizabeth; Sekiguchi, Yuko; Sekihata, Daiki; Selyuzhenkov, Ilya; Senosi, Kgotlaesele; Senyukov, Serhiy; Serradilla Rodriguez, Eulogio; Sett, Priyanka; Sevcenco, Adrian; Shabanov, Arseniy; Shabetai, Alexandre; Shahoyan, Ruben; Shaikh, Wadut; Shangaraev, Artem; Sharma, Anjali; Sharma, Ankita; Sharma, Meenakshi; Sharma, Natasha; Sheikh, Ashik Ikbal; Shigaki, Kenta; Shimomura, Maya; Shirinkin, Sergey; Shou, Qiye; Shtejer Diaz, Katherin; Sibiryak, Yury; Siddhanta, Sabyasachi; Sielewicz, Krzysztof Marek; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Simatovic, Goran; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singh, Randhir; Singhal, Vikas; Sarkar - Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Slupecki, Maciej; Smirnov, Nikolai; Snellings, Raimond; Snellman, Tomas Wilhelm; Song, Jihye; Soramel, Francesca; Sorensen, Soren Pontoppidan; Sozzi, Federica; Sputowska, Iwona Anna; Stachel, Johanna; Stan, Ionel; Stankus, Paul; Stenlund, Evert Anders; Stocco, Diego; Storetvedt, Maksim Melnik; Strmen, Peter; Alarcon Do Passo Suaide, Alexandre; 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Van Hoorne, Jacobus Willem; Van Leeuwen, Marco; Vande Vyvre, Pierre; Varga, Dezso; Diozcora Vargas Trevino, Aurora; Vargyas, Marton; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vauthier, Astrid; Vazquez Doce, Oton; Vechernin, Vladimir; Veen, Annelies Marianne; Vercellin, Ermanno; Vergara Limon, Sergio; Vermunt, Luuk; Vernet, Renaud; Vertesi, Robert; Vickovic, Linda; Viinikainen, Jussi Samuli; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Villatoro Tello, Abraham; Vinogradov, Alexander; Virgili, Tiziano; Vislavicius, Vytautas; Vodopyanov, Alexander; Volkl, Martin Andreas; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; Von Haller, Barthelemy; Vorobyev, Ivan; Voscek, Dominik; Vranic, Danilo; Vrlakova, Janka; Wagner, Boris; Wang, Hongkai; Wang, Mengliang; Watanabe, Yosuke; Weber, Michael; Weber, Steffen Georg; Wegrzynek, Adam; Weiser, Dennis Franz; Wenzel, Sandro Christian; Wessels, Johannes Peter; Westerhoff, Uwe; Whitehead, Andile Mothegi; Wiechula, Jens; Wikne, Jon; Wilk, Grzegorz Andrzej; Wilkinson, Jeremy John; Willems, Guido Alexander; Williams, Crispin; Willsher, Emily; Windelband, Bernd Stefan; Witt, William Edward; Xu, Ran; Yalcin, Serpil; Yamakawa, Kosei; Yano, Satoshi; Yin, Zhongbao; Yokoyama, Hiroki; Yoo, In-kwon; Yoon, Jin Hee; Yurchenko, Volodymyr; Zaccolo, Valentina; Zaman, Ali; Zampolli, Chiara; Correa Zanoli, Henrique Jose; Zardoshti, Nima; Zarochentsev, Andrey; Zavada, Petr; Zavyalov, Nikolay; Zbroszczyk, Hanna Paulina; Zhalov, Mikhail; Zhang, Xiaoming; Zhang, Yonghong; Zhang, Zuman; Zhao, Chengxin; Zherebchevskii, Vladimir; Zhigareva, Natalia; Zhou, Daicui; Zhou, You; Zhou, Zhuo; Zhu, Hongsheng; Zhu, Jianhui; Zhu, Ya; Zichichi, Antonino; Zimmermann, Markus Bernhard; Zinovjev, Gennady; Zmeskal, Johann; Zou, Shuguang

2018-01-01

Inclusive J/$\\psi$ production is studied in Xe-Xe interactions at a centre-of-mass energy per nucleon pair of $\\sqrt{s_{NN}}$ = 5.44 TeV, using the ALICE detector at the CERN LHC. The J/$\\psi$ meson is reconstructed via its decay into a muon pair, in the centre-of-mass rapidity interval 2.5 < y < 4 and down to zero transverse momentum. In this Letter, the nuclear modification factors $R_{AA}$ for inclusive J/$\\psi$, measured in the centrality range 0-90% as well as in the centrality intervals 0-20% and 20-90% are presented. The $R_{AA}$ values are compared to previously published results for Pb-Pb collisions at $\\sqrt{s_{NN}}$ = 5.02 TeV and to the calculation of a transport model. A good agreement is found between Xe-Xe and Pb-Pb results as well as between data and the model.

Beta-gamma counting system for Xe fission products

International Nuclear Information System (INIS)

Reeder, P.L.; Bowyer, T.W.; Perkins, R.W.

1998-01-01

A beta-gamma coincidence counting system has been developed for automated analysis of Xe gas samples separated from air. The Xe gas samples are contained in a cylindrical plastic scintillator cell located between two NaI(Tl) scintillation detectors. The X-ray and gamma spectra gated by coincident events in the plastic scintillator cell are recorded for each NaI(Tl) crystal. The characteristic signatures of the 131m Xe, 133g Xe, 133m Xe, and 135g Xe isotopes of interest for nuclear test-ban verification as well as the procedures and results of absolute efficiency measurements are described. A NaI(Tl) crystal with provision for 4 sample cells has been implemented for the system to be deployed in the field. Examples of data on ambient air samples in New York City obtained with the field prototype are presented. (author)

Velocity dependence of the Penning ionization of D atoms by He(21S) and H2(23S) atoms

International Nuclear Information System (INIS)

Fort, J.; Laucagne, J.J.; Pesnelle, A.; Watel, G.

1975-01-01

A time-of-flight technique has been developed for the study of the velocity dependence of the cross section for Penning ionization of D atoms by metastable He atoms: He(2 1 S)+D→He(1 1 S)+D + +e - , He(2 3 S)+D→He(1 1 S)+D + e - [fr

Melting in Two-Dimensional Lennard-Jones Systems: Observation of a Metastable Hexatic Phase

International Nuclear Information System (INIS)

Chen, K.; Kaplan, T.; Mostoller, M.

1995-01-01

Large scale molecular dynamics simulations of two-dimensional melting have been carried out using a recently revised Parrinello-Rahman scheme on massively parallel supercomputers. A metastable state is observed between the solid and liquid phases in Lennard-Jones systems of 36 864 and 102 400 atoms. This intermediate state shows the characteristics of the hexatic phase predicted by the theory of Kosterlitz, Thouless, Halperin, Nelson, and Young

/sup 133/Xe and /sup 135/Xe interference with in vivo low-energy measurement systems

Energy Technology Data Exchange (ETDEWEB)

Cohen, N; Lo Sasso, T; Lei, W [New York Univ., NY (USA). Inst. of Environmental Medicine

1980-03-01

Fission product /sup 133/Xe and /sup 135/Xe are released to the atmosphere during normal reactor operation. With increasing numbers of nuclear power stations there will be an increase in the ambient level of these isotopes. They do not present an appreciable long-term health hazard because of their inert nature and relatively short half-lives. However, their presence in the air of a whole-body counter may interfere significantly with in vivo low-energy photon counting procedures by contributing to the background count-rate in the energy region below 300 keV. This applies particularly to lung and whole-body measurements with dual thin crystal NaI(Tl)-CsI(Tl) scintillation detectors for actinide nuclides. It is important, therefore, that gamma spectroscopists should be aware of the possible presence of /sup 133/Xe and /sup 135/Xe in the air of their whole-body counting facilities, particularly if these are near to reactors and do not have traps for removal of inert gases from their air supplies.

Xenon gas field ion source from a single-atom tip

Science.gov (United States)

Lai, Wei-Chiao; Lin, Chun-Yueh; Chang, Wei-Tse; Li, Po-Chang; Fu, Tsu-Yi; Chang, Chia-Seng; Tsong, T. T.; Hwang, Ing-Shouh

2017-06-01

Focused ion beam (FIB) systems have become powerful diagnostic and modification tools for nanoscience and nanotechnology. Gas field ion sources (GFISs) built from atomic-size emitters offer the highest brightness among all ion sources and thus can improve the spatial resolution of FIB systems. Here we show that the Ir/W(111) single-atom tip (SAT) can emit high-brightness Xe+ ion beams with a high current stability. The ion emission current versus extraction voltage was analyzed from 150 K up to 309 K. The optimal emitter temperature for maximum Xe+ ion emission was ˜150 K and the reduced brightness at the Xe gas pressure of 1 × 10-4 torr is two to three orders of magnitude higher than that of a Ga liquid metal ion source, and four to five orders of magnitude higher than that of a Xe inductively coupled plasma ion source. Most surprisingly, the SAT emitter remained stable even when operated at 309 K. Even though the ion current decreased with increasing temperature, the current at room temperature (RT) could still reach over 1 pA when the gas pressure was higher than 1 × 10-3 torr, indicating the feasibility of RT-Xe-GFIS for application to FIB systems. The operation temperature of Xe-SAT-GFIS is considerably higher than the cryogenic temperature required for the helium ion microscope (HIM), which offers great technical advantages because only simple or no cooling schemes can be adopted. Thus, Xe-GFIS-FIB would be easy to implement and may become a powerful tool for nanoscale milling and secondary ion mass spectroscopy.

Metastable gravity on classical defects

International Nuclear Information System (INIS)

Ringeval, Christophe; Rombouts, Jan-Willem

2005-01-01

We discuss the realization of metastable gravity on classical defects in infinite-volume extra dimensions. In dilatonic Einstein gravity, it is found that the existence of metastable gravity on the defect core requires violation of the dominant energy condition for codimension N c =2 defects. This is illustrated with a detailed analysis of a six-dimensional hyperstring minimally coupled to dilaton gravity. We present the general conditions under which a codimension N c >2 defect admits metastable modes, and find that they differ from lower codimensional models in that, under certain conditions, they do not require violation of energy conditions to support quasilocalized gravity

Molecular dynamics simulations of adsorption and diffusion of Xe on bare and Xe covered Pt(111)

NARCIS (Netherlands)

Jong, de F.; Jansen, A.P.J.

1994-01-01

Molecular dynamics simulations are used to calculate adsorption probabilities and diffusion coefficients of Xe on Pt(111) and Xe/Pt(111). Experimental trends are reproduced. The adsorption mechanism is found to be the modified Kisliuk model, with the addition of direct and indirect insertion in the

Photoionisation study of Xe.CF{sub 4} and Kr.CF{sub 4} van-der-Waals molecules

Energy Technology Data Exchange (ETDEWEB)

Alekseev, V. A., E-mail: alekseev@va3474.spb.edu; Kevorkyants, R. [St. Petersburg State University, 7/9 Universitetskaya Nab., St. Petersburg 199034 (Russian Federation); Garcia, G. A.; Nahon, L. [Synchrotron Soleil, Orme des Merisiers, St. Aubin BP 48, 91192 Gif sur Yvette Cedex (France)

2016-05-14

We report on photoionization studies of Xe.CF{sub 4} and Kr.CF{sub 4} van-der-Waals complexes produced in a supersonic expansion and detected using synchrotron radiation and photoelectron-photoion coincidence techniques. The ionization potential of CF{sub 4} is larger than those of the Xe and Kr atoms and the ground state of the Rg.CF{sub 4}{sup +} ion correlates with Rg{sup +} ({sup 2}P{sub 3/2}) + CF{sub 4}. The onset of the Rg.CF{sub 4}{sup +} signals was found to be only ∼0.2 eV below the Rg ionization potential. In agreement with experiment, complementary ab initio calculations show that vertical transitions originating from the potential minimum of the ground state of Rg.CF{sub 4} terminate at a part of the potential energy surfaces of Rg.CF{sub 4}{sup +}, which are approximately 0.05 eV below the Rg{sup +} ({sup 2}P{sub 3/2}) + CF{sub 4} dissociation limit. In contrast to the neutral complexes, which are most stable in the face geometry, for the Rg.CF{sub 4}{sup +} ions, the calculations show that the minimum of the potential energy surface is in the vertex geometry. Experiments which have been performed only with Xe.CF{sub 4} revealed no Xe.CF{sub 4}{sup +} signal above the first ionization threshold of Xe, suggesting that the Rg.CF{sub 4}{sup +} ions are not stable above the first dissociation limit.

SEP-Kr and SEP-Xe in Lunar Ilmenite and the Ar/Kr/Xe Ratio in the Solar Wind

Science.gov (United States)

Wieler, R.; Baur, H.; Signer, P.

1992-07-01

We analyzed all five noble gases in an ilmenite sample from lunar soil 71501 by closed system stepped etching (CSSE), thus extending our CSSE studies of solar noble gases (Wieler et al., 1986; Benkert et al., 1988) to Kr and Xe. He, Ne, Ar isotopes: We observe the familiar presence of two solar noble gas components: step 1 shows ^4He/^3He = 2250, ^20Ne/^22Ne = 13.8, and ^36Ar/^38Ar=5.46. The first two ratios are essentially identical to modern solar wind values (SWC; Geiss, 1973), indicating an isotopically unfractionated SW noble gas reservoir in lunar ilmenite. The Ne data-points of later steps fall on a straight line and reach the SEP-Ne point (^20Ne/^22Ne = 11.3). The slope of this line indicates mass dependent fractionation between SW-Ne and SEP-Ne. SEP-He (^4He/^3He = 4650 +-100) and SEP-Ar (^36Ar/^38Ar = 4.89+-0.05) are also observed (latter two numbers slightly revised compared to Wieler et al., 1992). Kr, Xe isotopes: Kr in those two steps that release pure SW-Ne is very slightly lighter than atmospheric Kr (^86Kr/^84Kr = 0.3041; see also Wieler et al., 1992). We interpret this to be SW-Kr in soil 71501. Steps containing (isotopically heavier) SEP-Ne likewise release heavier Kr, interpreted accordingly as SEP-Kr (^86Kr/^84Kr = 0.323). Similarly, a light Xe component is released first (SW-Xe, ^136Xe/^132Xe = 0.3003), followed by heavier SEP-Xe (^136Xe/^132Xe = 0.319). The data are consistent with both Kr and Xe in SW and SEP components to be related by mass fractionation. The relation first proposed by Benkert et al. (1988) between a ratio R(m(sub)2,m(sub)1) of two isotopes with masses m(sub)2>m(sub)1 in SW and SEP now holds for all five noble gases: (R(sub)SW-R(sub)SEP)/R(sub)SW = (2+-0.13)*(m(sub)2- m(sub)1)/m(sub)2. Since m(sub)2~m(sub)1, this relation may also be written as: R(sub)SEP/R(sub)SW ~ (m(sub)1/m(sub)2)^2 (Geiss and Bochsler, 1991). Element ratios: ^4He/^36Ar and ^20Ne/^36Ar rise from values several times below SWC to essentially SWC ratios in

Desensitization of metastable intermolecular composites

Science.gov (United States)

Busse, James R [South Fork, CO; Dye, Robert C [Los Alamos, NM; Foley, Timothy J [Los Alamos, NM; Higa, Kelvin T [Ridgecrest, CA; Jorgensen, Betty S [Jemez Springs, NM; Sanders, Victor E [White Rock, NM; Son, Steven F [Los Alamos, NM

2011-04-26

A method to substantially desensitize a metastable intermolecular composite material to electrostatic discharge and friction comprising mixing the composite material with an organic diluent and removing enough organic diluent from the mixture to form a mixture with a substantially putty-like consistency, as well as a concomitant method of recovering the metastable intermolecular composite material.

Metastability and avalanche dynamics in strongly correlated gases with long-range interactions

Science.gov (United States)

Hruby, Lorenz; Dogra, Nishant; Landini, Manuele; Donner, Tobias; Esslinger, Tilman

2018-03-01

We experimentally study the stability of a bosonic Mott insulator against the formation of a density wave induced by long-range interactions and characterize the intrinsic dynamics between these two states. The Mott insulator is created in a quantum degenerate gas of 87-Rubidium atoms, trapped in a 3D optical lattice. The gas is located inside and globally coupled to an optical cavity. This causes interactions of global range, mediated by photons dispersively scattered between a transverse lattice and the cavity. The scattering comes with an atomic density modulation, which is measured by the photon flux leaking from the cavity. We initialize the system in a Mott-insulating state and then rapidly increase the global coupling strength. We observe that the system falls into either of two distinct final states. One is characterized by a low photon flux, signaling a Mott insulator, and the other is characterized by a high photon flux, which we associate with a density wave. Ramping the global coupling slowly, we observe a hysteresis loop between the two states—a further signature of metastability. A comparison with a theoretical model confirms that the metastability originates in the competition between short- and global-range interactions. From the increasing photon flux monitored during the switching process, we find that several thousand atoms tunnel to a neighboring site on the timescale of the single-particle dynamics. We argue that a density modulation, initially forming in the compressible surface of the trapped gas, triggers an avalanche tunneling process in the Mott-insulating region.

Metastable Magnesium fluorescence spectroscopy using a frequency-stabilized 517 nm laser

DEFF Research Database (Denmark)

He, Ming; Jensen, Brian B; Therkildsen, Kasper T

2009-01-01

We present a laser operating at 517 nm for our Magnesium laser-cooling and atomic clock project. A two-stage Yb-doped fiber amplifier (YDFA) system generates more than 1.5 W of 1034 nm light when seeded with a 15 mW diode laser. Using a periodically poled lithium niobate (PPLN) waveguide, we obta...... obtained more than 40 mW of 517 nm output power by single pass frequency doubling. In addition, fluorescence spectroscopy of metastable magnesium atoms could be used to stabilize the 517 nm laser to an absolute frequency within 1 MHz.......We present a laser operating at 517 nm for our Magnesium laser-cooling and atomic clock project. A two-stage Yb-doped fiber amplifier (YDFA) system generates more than 1.5 W of 1034 nm light when seeded with a 15 mW diode laser. Using a periodically poled lithium niobate (PPLN) waveguide, we...

Preparation and dosimetry of reactor-produced Xe-125 for ventilation scintigraphy

International Nuclear Information System (INIS)

Junker, D.; Cordes, H.

1978-01-01

Xe-125 is produced in the reactor by the (n, γ)-reaction from Xe-124. The natural abundance of Xe-124, however, is only 0,1 percent. As the costs for Xe-124 enriched Xenon are considerable, natural Xenon is activated in the epithermal energy region. In contrast to the other stable isotopes of Xenon, Xe-124 shows a large resonance cross section in this energy region. The main activation product is Xe-125. In addition, a few nuclides (e.g. Xe-125m, Xe-127m, Xe-137) are produced, which due to their short half lives give no contribution to radiation dose. Radiocontaminants originating from parent-daughter decay (e.g. Cs-135 and Cs-137) are separated by filtration of the gas. I-125 produced by the decay of Xe-125 is removed by filtering of the gas before administration to the patient. Typical yields of a sample capsule are 20 to 30 mCi Xe-125 after irradiation of 4 hours in an epithermal flux of approximately 2.10 -11 s -1 cm -2 . The residual contaminants contributing to the radiation dose are Xe-135 and Xe-129m. Depending on the irradiation time they amount to a few percent of the total activity. Using Xe-125 for lung ventilation studies results in considerable reduction of radiation dose as compared to Xe-133. An additional advantage is the better tissue penetration of Xe-125 (γ-energies at 188 keV (55%) and 243 keV (29%)) permitting the reduction of the dose for a study. The daughter nuclide I-125 generated during the study causes only a few mrem of radiation dose if the thyroid is blocked. Altogether Xe-125 as compared to Xe-133 offers more suitable γ-energies for lung ventilation studies and in addition a reduced radiation dose to the patient. (author)

Centrality determination using the Glauber model in Xe-Xe collisions at $\\sqrt{s_{\\rm NN}} = 5.44$ TeV

CERN Document Server

2018-01-01

This document describes the methods used by the ALICE Collaboration for determining the centrality of Xe-Xe collisions at $\\sqrt{s_{\\rm NN}} = 5.44$ TeV at the LHC within the Glauber model. The half-density radius $R$ and the diffusivity $a$ describing the Xe-129 nucleus with a 2-parameter Fermi distribution have been derived from a recent electron scattering measurement for the Xe-132 nucleus. The deformation parameter $\\beta$ has been derived by an interpolation between measured deformation parameters for the even-$A$ Xe isotopes. The inelastic nucleon-nucleon cross-section at $\\sqrt{s_{\\rm NN}} = 5.44$ TeV has been estimated by interpolation of pp data at different center-of-mass energies. The particle multiplicity per nucleon-nucleon collision has been parameterized by a negative binomial distribution (NBD) and a number of independently emitting sources (ancestors) given by a linear combination of $N_{\\rm part}$ and $N_{\\rm coll}$. The NBD parameters $\\mu$ and $k$ and the ancestor parameter $f$ are then...

Metastable dark energy

Directory of Open Access Journals (Sweden)

Ricardo G. Landim

2017-01-01

Full Text Available We build a model of metastable dark energy, in which the observed vacuum energy is the value of the scalar potential at the false vacuum. The scalar potential is given by a sum of even self-interactions up to order six. The deviation from the Minkowski vacuum is due to a term suppressed by the Planck scale. The decay time of the metastable vacuum can easily accommodate a mean life time compatible with the age of the universe. The metastable dark energy is also embedded into a model with SU(2R symmetry. The dark energy doublet and the dark matter doublet naturally interact with each other. A three-body decay of the dark energy particle into (cold and warm dark matter can be as long as large fraction of the age of the universe, if the mediator is massive enough, the lower bound being at intermediate energy level some orders below the grand unification scale. Such a decay shows a different form of interaction between dark matter and dark energy, and the model opens a new window to investigate the dark sector from the point-of-view of particle physics.

Relativistic many-body calculation of energies, transition rates, lifetimes, and multipole polarizabilities in Cs-like La iii

Science.gov (United States)

Safronova, U. I.; Safronova, M. S.

2014-05-01

Excitation energies of the [Xe]nd (n =5-9), [Xe]ns (n =6-10), [Xe]np (n =6-9), [Xe]nf (n =4-8), and [Xe]ng (n =5-8) states in La iii, where [Xe] = 1s22s22p63s23p63d104s24p64d105s25p6, are evaluated. Electric dipole matrix elements for the allowed transitions between the low-lying [Xe]nd, [Xe]ns, [Xe]np, [Xe]nf, and [Xe]ng states in the La iii ion are calculated using the high-precision relativistic all-order method where all single, double, and partial triple excitations of the Dirac-Fock wave functions are included to all orders of perturbation theory. Recommended values are provided for a large number of electric dipole matrix elements, oscillator strengths, transition rates, and lifetimes. Scalar and tensor polarizabilities of the states listed above are evaluated. The uncertainties of the recommended values are estimated. Electric quadrupole and magnetic dipole matrix elements are calculated to determine lifetimes of the 5d5/2 and 6s metastable levels. The ground-state E1, E2, and E3 static polarizabilities are calculated. This work provides recommended values critically evaluated for their accuracy for a number of La iii atomic properties for use in planning and analysis of various experiments as well as theoretical modeling.

Xe-129 NMR chemical shift in Xe@C-60 calculated at experimental conditions: Essential role of the relativity, dynamics, and explicit solvent

Czech Academy of Sciences Publication Activity Database

Standara, Stanislav; Kulhánek, P.; Marek, R.; Straka, Michal

2013-01-01

Roč. 34, č. 22 (2013), s. 1890-1898 ISSN 0192-8651 R&D Projects: GA ČR GA203/09/2037; GA ČR GA13-03978S Grant - others:7th European Community Framework Program(XE) FP7-286154; CEITEC-Central European Institute of Technology (European Regional Development)(XE) CZ.1.05/1.1.00/02.0068; Operational Program Research and Development for Innovations(XE) CZ.1.05/3.2.00/08.0144 Institutional support: RVO:61388963 Keywords : Xe-129 NMR * Xe@C-60 * dynamical averaging * explicit solvent * relativistic effects Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.601, year: 2013

Production of pure 133mXe for CTBTO

Science.gov (United States)

Peräjärvi, K.; Eronen, T.; Gorelov, D.; Hakala, J.; Jokinen, A.; Kettunen, H.; Kolhinen, V.; Laitinen, M.; Moore, I. D.; Penttilä, H.; Rissanen, J.; Saastamoinen, A.; Toivonen, H.; Turunen, J.; Äystö, J.

2014-01-01

Underground nuclear weapon detonations release gaseous species into the atmosphere. The most interesting isotopes/isomers from the detection point of view are 131mXe, 133mXe, 133Xe and 135Xe. We have developed a method that employs high-precision Penning trap mass spectrometry at the JYFLTRAP facility, the University of Jyväskylä, to produce pure calibration samples of these isotopes/isomers. Among developments this work required a new mass resolution record of a few parts-per-million. Here the status and future plans of the project are reviewed.

INTERSTELLAR METASTABLE HELIUM ABSORPTION AS A PROBE OF THE COSMIC-RAY IONIZATION RATE

International Nuclear Information System (INIS)

Indriolo, Nick; McCall, Benjamin J.; Hobbs, L. M.; Hinkle, K. H.

2009-01-01

The ionization rate of interstellar material by cosmic rays has been a major source of controversy, with different estimates varying by three orders of magnitude. Observational constraints of this rate have all depended on analyzing the chemistry of various molecules that are produced following cosmic-ray ionization, and in many cases these analyses contain significant uncertainties. Even in the simplest case (H + 3 ), the derived ionization rate depends on an (uncertain) estimate of the absorption path length. In this paper, we examine the feasibility of inferring the cosmic-ray ionization rate using the 10830 A absorption line of metastable helium. Observations through the diffuse clouds toward HD 183143 are presented, but yield only an upper limit on the metastable helium column density. A thorough investigation of He + chemistry reveals that only a small fraction of He + will recombine into the triplet state and populate the metastable level. In addition, excitation to the triplet manifold of helium by secondary electrons must be accounted for as it is the dominant mechanism which produces He* in some environments. Incorporating these various formation and destruction pathways, we derive new equations for the steady state abundance of metastable helium. Using these equations in concert with our observations, we find ζ He -15 s -1 , an upper limit about 5 times larger than the ionization rate previously inferred for this sight line using H + 3 . While observations of interstellar He* are extremely difficult at present, and the background chemistry is not nearly as simple as previously thought, potential future observations of metastable helium would provide an independent check on the cosmic-ray ionization rate derived from H + 3 in diffuse molecular clouds, and, perhaps more importantly, allow the first direct measurements of the ionization rate in diffuse atomic clouds.

LABORATORY FREQUENCY REDISTRIBUTION FUNCTION FOR THE POLARIZED Λ-TYPE THREE-TERM ATOM

Energy Technology Data Exchange (ETDEWEB)

Casini, R. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Manso Sainz, R. [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

2016-12-20

We present the frequency redistribution function for a polarized three-term atom of the Λ-type in the collisionless regime, and we specialize it to the case where both the initial and final terms of the three-state transition are metastable (i.e., with infinitely sharp levels). This redistribution function represents a generalization of the well-known R {sub II} function to the case where the lower terms of the transition can be polarized and carry atomic coherence, and it can be applied to the investigation of polarized line formation in tenuous plasmas, where collisional rates may be low enough that anisotropy-induced atomic polarization survives even in the case of metastable levels.

Precise measurement of magnetic field gradients from free spin precession signals of He-3 and Xe-129 magnetometers

NARCIS (Netherlands)

Allmendinger, Fabian; Blümler, Peter; Doll, Michael; Grasdijk, Oliver; Heil, Werner; Jungmann, Klaus; Karpuk, Sergej; Krause, Hans-Joachim; Offenhäuser, Andreas; Repetto, Maricel; Schmidt, Ulrich; Sobolev, Yuri; Tullney, Kathlyne; Willmann, Lorenz; Zimmer, Stefan

2017-01-01

We report on precise measurements of magnetic field gradients extracted from transverse relaxation rates of precessing spin samples. The experimental approach is based on the free precession of gaseous, nuclear spin polarized He-3 and (12)9Xe atoms in a spherical cell inside a magnetic guiding field

High spin {gamma}-ray spectroscopy of {sup 121,122}Xe

Energy Technology Data Exchange (ETDEWEB)

Timmers, H [Liverpool Univ. (United Kingdom). Oliver Lodge Lab.; [Department of Physics, SUNY at Stony Brook, NY (United States); Riley, M A; Hanna, F; Mullins, S M; Sharpey-Schafer, J F [Liverpool Univ. (United Kingdom). Oliver Lodge Lab.; Hughes, J R; Fossan, D B; Liang, Y; Ma, R; Xu, N [Department of Physics, SUNY at Stony Brook, NY (United States); Simpson, J; Bentley, M A [Daresbury Lab. (United Kingdom); Bengtsson, T [Lund Univ. (Sweden). Dept. of Mathematical Physics; Wyss, R [Institute for Heavy Ion Research, Oak Ridge, TN (United States)

1992-08-01

High-spin states have been populated in {sup 121,122}Xe using the reactions {sup 108}Pd({sup 16}O,3n){sup 121}Xe at 65 MeV and {sup 96}Zr({sup 30}Si,4n/5n){sup 122}Xe/{sup 121}Xe at 135 MeV. Coincident {gamma} rays following the neutron evaporation were detected by six Compton-suppressed Ge detectors and the TESSA3 array respectively. The level structure of {sup 121}Xe and {sup 122}Xe has been extended up to 47/2 {Dirac_h} and 32 {Dirac_h} respectively. In {sup 121}Xe a coupled band was found feeding the 19/2{sup -} level. In {sup 122}Xe several decays are suggested to be a sequence of stretched E2 quadrupole transitions connecting states of positive parity. While in {sup 121}Xe this phenomenon was not observed, at high spin a phase transition from prolate collective rotation to oblate single particle excitation was detected in {sup 122}Xe. For the new, probably positive parity side band in{sup 122}Xe a four quasi-neutron or a two quasi-proton configuration of h{sub 11/2} quasi-nucleons might be considered. The positive parity high spin structure in {sup 122}Xe contains three I{sup {pi}} = 22{sup +} states of different character. This is predicted by TRS (total Routhian surface) calculations, which identify these states as two shapes with predominantly prolate collective characteristic and the third as an oblate single particle configuration. 12 refs., 3 figs.

¹³⁶ Xe enrichment through cryogenic distillation

Energy Technology Data Exchange (ETDEWEB)

Back, Henning O.; Bottenus, Daniel R.; Clayton, Christopher K.; Stephenson, David E.; TeGrotenhuis, Ward E.

2017-09-01

The next generation of 136Xe neutrinoless double beta decay experiments will require on the order of 5 tons of enriched 136Xe. By estimating the relative volatilities of the xenon isotopes and using standard chemical engineering techniques we explore the feasibility of using cryogenic distillation to produce 5 tons of 80% enriched 136Xe in 5-6 years. With current state-of-the-art distillation column packing materials we can estimate the total height of a traditional cryogenic distillation column. We also, report on how Micro Channel Distillation may reduce the overall size of a distillation system for 136Xe production.

Recoil distance lifetime measurements in 122,124Xe

Science.gov (United States)

Govil, I. M.; Kumar, A.; Iyer, H.; Li, H.; Garg, U.; Ghugre, S. S.; Johnson, T.; Kaczarowski, R.; Kharraja, B.; Naguleswaran, S.; Walpe, J. C.

1998-02-01

Lifetimes of the lower-excited states in 122,124Xe are measured using the recoil-distance Doppler-shift technique. The reactions 110Pd(16O,4n)122Xe and 110Pd(18O,4n)124Xe at a beam energy of 66 MeV were used for this experiment. The lifetimes of the 2+, 4+, 6+, and 8+ states of the ground state band were extracted using the computer code LIFETIME including the corrections due to the side feeding and the nuclear deorientation effects. The lifetime of the 2+ state in 122Xe agrees with the recoil distance method (RDM) measurements but for the 124Xe it does not agree with the RDM measurements but agrees with the Coulomb-excitation experiment. The measured B(E2) values for both the nuclei are compared with the standard algebraic and the multishell models.

Cluster-surface collisions: Characteristics of Xe55- and C20 - Si[111] surface bombardment

International Nuclear Information System (INIS)

Cheng, H.

1999-01-01

Molecular dynamics (MD) simulations are performed to study the cluster-surface collision processes. Two types of clusters, Xe 55 and C 20 are used as case studies of materials with very different properties. In studies of Xe 55 - Si[111] surface bombardment, two initial velocities, 5.0 and 10.0 km/s (normal to the surface) are chosen to investigate the dynamical consequences of the initial energy or velocity in the cluster-surface impact. A transition in the speed of kinetic energy propagation, from subsonic velocities to supersonic velocities, is observed. Energy transfer, from cluster translational motion to the substrate, occurs at an extremely fast rate that increases as the incident velocity increases. Local melting and amorphous layer formation in the surfaces are found via energetic analysis of individual silicon atoms. For C 20 , the initial velocity ranges from 10 to 100 km/s. The clusters are damaged immediately upon impact. Similar to Xe 55 , increase in the potential energy is larger than the increase in internal kinetic energy. However, the patterns of energy distribution are different for the two types of clusters. The energy transfer from the carbon clusters to Si(111) surface is found to be slower than that found in the Xe clusters. Fragmentation of the carbon cluster occurs when the initial velocity is greater than 30 km/s. At 10 km/s, the clusters show recrystallization at later times. The average penetration depth displays a nonlinear dependence on the initial velocity. Disturbance in the surface caused by C 20 is discussed and compared to the damage caused by Xe 55 . Energetics, structures, and dynamics of these systems are fully analyzed and characterized. copyright 1999 American Institute of Physics

Experimental investigation of the chemistry of excited states of rare gases. Technical progress report, October 15, 1975--July 15, 1976

International Nuclear Information System (INIS)

Setser, D.W.

1976-07-01

Total quenching rate constants and branching ratios for rare gas halide excimer formation have been measured for Ar( 3 P 0 , 2 ), Kr( 3 P 2 ) and Xe( 3 P 2 ) reacting with chlorine and fluorine-containing molecules. Emphasis was focused on systems giving KrF* and XeF* as products. All halogen containing molecules quench metastable rare gas atoms with gas kinetic cross-sections. However, only diatomic halogens and small molecules with O-X or N-X bonds quench the metastable with high branching ratios for excimer formation. The product channels for the reagents which do not yield the rare gas halides as the main exit channel remain to be identified. The work that has been done provides a good survey of halogen donors. This work will assist in selection of the best halogen-containing molecules for use in rare gas halide excimer lasers. Tunable dye laser fluorescence experiments have been done to obtain radiative lifetimes and two body quenching rate constants (with ground state Ar) for excited states of Ar*(3p 5 ,4p) and Ar*

Electron-impact ionization of heavy atomic ions

International Nuclear Information System (INIS)

Pindzola, M.S.; Griffin, D.C.; Bottcher, C.

1987-01-01

General theoretical methods for the calculation of direct and indirect processes in the electron-impact ionization of heavy atomic ions are reviewed. Cross section results for Xe 8+ and U 89+ are presented. 12 refs., 4 figs

Quenching reactions of electronically excited atoms

International Nuclear Information System (INIS)

Setser, D.W.

2001-01-01

The two-body, thermal quenching reactions of electronically excited atoms are reviewed using excited states of Ar, Kr, and Xe atoms as examples. State-specific interstate relaxation and excitation-transfer reactions with atomic colliders are discussed first. These results then are used to discuss quenching reactions of excited-state atoms with diatomic and polyatomic molecules, the latter have large cross sections, and the reactions can proceed by excitation transfer and by reactive quenching. Excited states of molecules are not considered; however, a table of quenching rate constants is given for six excited-state molecules in an appendix

Asymmetric output profile of Xe Laser

NARCIS (Netherlands)

Blok, F.J.; Rubin, P.L.; Verschuur, Jeroen W.J.; Witteman, W.J.

2001-01-01

A new set of asymmetric modes was recently revealed in a Xe slab laser with pronounced lens effects originating from gas heating in the discharge. The appearance of these modes is a threshold effect. Their domain of existence in the Xe laser is discussed. It is shown that mode competition can result

Reflection-type hologram for atoms

International Nuclear Information System (INIS)

Shimizu, Fujio; Fujita, Jun-ichi

2002-01-01

A cold metastable neon atomic beam was manipulated with a reflective amplitude hologram that was encoded on a silicon surface. A black-and-white pattern of atoms was reconstructed on a microchannel plate detector. The hologram used the enhanced quantum reflection developed by authors and was made of a two-dimensional array of rectangular low and high reflective cells. The surface of the high reflective cell was composed of regularly spaced roof-shaped ridges, while the low reflective cell was simply a flat surface. The hologram was the first demonstration of reflective atom-optical elements that used universal interaction between a neutral atom and solid surface

Lifetime of the metastable 23S1 state in stored Li+ ions

International Nuclear Information System (INIS)

Knight, R.D.

1979-04-01

A laser-induced fluorescence technique combined with the observation of spontaneous magnetic dipole photons from the highly metastable 2 3 S 1 state of Li + was used to measure the radiative lifetime of this state. The ions are created by electron impact on a lithium atomic beam and are subsequently stored for periods of many seconds in an RF-quadrupole ion trap. A tunable dye laser excites the 2 3 S--2 3 P, transition at 5485A, and the intercombination electric dipole transition 2 3 P 1 --1 1 S 0 at 202A is observed. This process depletes the metastable population in a time tau/sub d/ 3 S 1 / and provides a measure of the total number of metastables. Comparison with the rate of 210A spontaneously emitted photons yields a measured value for the 2 3 S 1 radiative lifetime of tau/sub rad/ = 58.6 +- 12.9 sec, where the quoted error represents 95% confidence levels. The theoretical lifetime is tau/sub theory/ = 49.0 sec. The measured value includes data taken with both 6 Li + and 7 Li + isotopes and was corrected for the slightly different detector efficiencies at 202A and 210A. A careful study of nonradiative quenching of the metastable state was necessary to understand observed differences between tau/sub rad/ and tau/sub 3 S 1 /, the total metastable lifetime. Spatial density profiles of the ions within the trap, useful for determining the ion temperature, were obtained by scanning the laser beam horizontally across the ion trap while storing 2 3 P 1 -- 1 S 0 photon counts as a function of the laser beam's position. Agreement with a simple equilibrium model, including space charge effects, is satisfactory. A study of the optical pumping process is necessary to understand the laser-ion interaction, and observational and theoretical data are presented. 47 references

High-j neutron excitations outside 136Xe

Science.gov (United States)

Talwar, R.; Kay, B. P.; Mitchell, A. J.; Adachi, S.; Entwisle, J. P.; Fujita, Y.; Gey, G.; Noji, S.; Ong, H. J.; Schiffer, J. P.; Tamii, A.

2017-08-01

The ν 0 h9 /2 and ν 0 i13 /2 strength at 137Xe, a single neutron outside the N =82 shell closure, has been determined using the 136Xe(α ,3He)137Xe reaction carried out at 100 MeV. We confirm the recent observation of the second 13 /2+ state and reassess previous data on the 9 /2- states, obtaining spectroscopic factors. These new data provide additional constraints on predictions of the same single-neutron excitations at 133Sn.

Long-range interactions of excited He atoms with ground-state noble-gas atoms

KAUST Repository

Zhang, J.-Y.; Qian, Ying; Schwingenschlö gl, Udo; Yan, Z.-C.

2013-01-01

The dispersion coefficients C6, C8, and C10 for long-range interactions of He(n1,3S) and He(n1,3P), 2≤n≤10, with the ground-state noble-gas atoms Ne, Ar, Kr, and Xe are calculated by summing over the reduced matrix elements of multipole transition

Measurement of collision-induced radiative deexcitation cross sections for metastable He*(2 1S) interacting with He, Ar, Kr, and Xe

International Nuclear Information System (INIS)

Dehnbostel, C.; Feltgen, R.; Hoffmann, G.

1990-01-01

The radiative deexcitation cross section for He * (2 1 S) in collisions with He has been measured in the collision energy range from 40 to 110 meV. The experimental results agree well with quantal distorted-wave calculations of Zygelman and Dalgarno [Phys. Rev. A 38, 1877 (1988)]. The measured radiative quenching cross sections for the systems He * (2 1 S)+Ar,Kr,Xe manifest a scaling law for fixed collision energy with α 2 as the scaling parameter, where α is the static dipole polarizability of the heavier rare gas

Kinetics of Ar+*(2G9/2) metastable ions and transport of argon ions in ICP reactor

NARCIS (Netherlands)

Sadeghi, N.; Derouard, J.; Grift, van de M.; Kroesen, G.M.W.; Hoog, de F.J.; Tachibana, K.; Watanabe, Y.

1997-01-01

The decay time of the argon Ar~~(2G912) metastable ions was measured in the afterglow of a low pressure pulsed helicon reactor. From the argon pressure and electron density dependence of this decay time, rate coefficients for quenching of these ions by argon atoms and by plasma electrons have been

Charged-particle nuclear modification factors in XeXe collisions at $\\sqrt{s_{\\mathrm{NN}}}=5.44~\\mathrm{TeV}$

CERN Document Server

CMS Collaboration

2018-01-01

The differential yields of charged particles having pseudorapidity within $|\\eta|6~\\mathrm{GeV}$. However, the suppression in XeXe events is slightly greater than in PbPb collisions when comparing selections having a similar number of participating nucleons.

Experimental ion mobility measurements in Xe-CF4 mixtures

Science.gov (United States)

Cortez, A. F. V.; Kaja, M. A.; Escada, J.; Santos, M. A. G.; Veenhof, R.; Neves, P. N. B.; Santos, F. P.; Borges, F. I. G. M.; Conde, C. A. N.

2018-04-01

In this paper we present the results of the ion mobility measurements made in gaseous mixtures of xenon with carbon tetrafluoride (Xe-CF4) for pressures ranging from 6 to 10 Torr (8-10.6 mbar) and for low reduced electric fields in the 10 to 25 Td range (2.4-6.1 kVṡcm‑1ṡbar‑1), at room temperature. The time-of-arrival spectra revealed one or two peaks depending on the gas relative abundances, which were attributed to CF3+ and to Xe2+ ions. However, for Xe concentrations above 60%, only one peak remains (Xe2+). The reduced mobilities obtained from the peak centroid of the time-of-arrival spectra are presented for Xe concentrations in the 5%-95% range.

Impact parameter sensitive study of inner-shell atomic processes in the experimental storage ring

Science.gov (United States)

Gumberidze, A.; Kozhuharov, C.; Zhang, R. T.; Trotsenko, S.; Kozhedub, Y. S.; DuBois, R. D.; Beyer, H. F.; Blumenhagen, K.-H.; Brandau, C.; Bräuning-Demian, A.; Chen, W.; Forstner, O.; Gao, B.; Gassner, T.; Grisenti, R. E.; Hagmann, S.; Hillenbrand, P.-M.; Indelicato, P.; Kumar, A.; Lestinsky, M.; Litvinov, Yu. A.; Petridis, N.; Schury, D.; Spillmann, U.; Trageser, C.; Trassinelli, M.; Tu, X.; Stöhlker, Th.

2017-10-01

In this work, we present a pilot experiment in the experimental storage ring (ESR) at GSI devoted to impact parameter sensitive studies of inner shell atomic processes for low-energy (heavy-) ion-atom collisions. The experiment was performed with bare and He-like xenon ions (Xe54+, Xe52+) colliding with neutral xenon gas atoms, resulting in a symmetric collision system. This choice of the projectile charge states was made in order to compare the effect of a filled K-shell with the empty one. The projectile and target X-rays have been measured at different observation angles for all impact parameters as well as for the impact parameter range of ∼35-70 fm.

Comparison of Xe single bubble sonoluminescence in water and sulfuric acid

International Nuclear Information System (INIS)

An Yu

2008-01-01

Using the equations of fluid mechanics with proper boundary conditions and taking account of the gas properties, we can numerically simulate the process of single bubble sonoluminescence, in which electron–neutral atom bremsstrahlung, electron—ion bremsstrahlung and recombination radiation, and the radiative attachment of electrons to atoms and molecules contribute to the light emission. The calculation can quantitatively or qualitatively interpret the experimental results. We find that the accumulated heat energy inside the compressed gas bubble is mostly consumed by the chemical reaction, therefore, the maximum degree of ionization inside Xe bubble in water is much lower than that in sulfuric acid, of which the vapour pressure is very low. In addition, in sulfuric acid much larger p a and R 0 are allowed which makes the bubbles in it much brighter than that in water. (classical areas of phenomenology)

Chemical activity of noble gases Kr and Xe and its impact on fission gas accumulation in the irradiated UO2 fuel

International Nuclear Information System (INIS)

Szuta, M.

2006-01-01

It is generally accepted that most of the insoluble inert gas atoms Xe and Kr produced during fissioning are retained in the fuel irradiated at a temperature lower than the threshold. Experimental data imply that we can assume that after irradiation exposure in excess of 10 18 fissions/cm 3 the single gas atom diffusion can be disregarded in description of fission gas behaviour. It is assumed that the vicinity of the fission fragment trajectory is the place of intensive irradiation induced chemical interaction of the fission gas products with UO 2 . Significant part of fission gas product is thus expected to be chemically bound in the matrix of UO 2 . Experiments with mixture of noble gases, coupled with theoretical calculations, provide strong evidence for direct bonds between Ar, Kr, or Xe atoms and the U atom of the CUO molecule. Because of its positive charge, the UO 2 2+ ion, which is isoelectronic with CUO, should form even stronger bonds with noble gas atoms, which could lead to a growing number of complexes that contain direct noble gas - to - actinide bonds. Considering the huge amount of gas immobilised in the UO 2 fuel the solution process and in consequence the re-solution process of rare gases is to be replaced by the chemical bonding process. This explains the fission gas accumulation in the irradiated UO 2 fuel. (author)

Level structures of 119Xe, 121Xe excited in (12C,3nγ) reactions and analysis of the hsub(11/2) bands in the IBF model

International Nuclear Information System (INIS)

Barci, V.; Gizon, J.; Gizon, A.

1982-02-01

Levels in 119 Xe, 121 Xe excited by the reactions 110 Cd, 112 Cd( 12 C,3nγ) 119 Xe, 121 Xe have been studied by in-beam γ-ray spectroscopic techniques. Several bands have been observed: hsub(11/2) and gsub(7/2) in 119 Xe, 121 Xe, a decoupled one in 121 Xe. A new level structure in 119 Xe found for the first time is assigned as the gsub(9/2) band generated by one hole in the gsub(9/2) neutron shell. The connections between these bands have been fixed in both nuclei. A detailed analysis is made for the hsub(11/2) level structure. An interpretation is given in terms of the interacting boson-fermion model where hsub(11/2), fsub(7/2) and hsub(9/2) fermion configurations are included

Predictions for multiplicities and flow harmonics in 5.44 TeV Xe+Xe collisions at the CERN Large Hadron Collider

Science.gov (United States)

Eskola, K. J.; Niemi, H.; Paatelainen, R.; Tuominen, K.

2018-03-01

We present the event-by-event next-to-leading-order perturbative-QCD + saturation + viscous hydrodynamics (EKRT) model predictions for the centrality dependence of the charged hadron multiplicity in the pseudorapidity interval |η |≤0.5 , and for the centrality dependence of the charged hadron flow harmonics vn{2 } obtained from two-particle cumulants, in √{sN N}=5.44 TeV Xe+Xe collisions at the CERN Large Hadron Collider. Our prediction for the 0-5 % central charged multiplicity is d Nch/d η =1218 ±46 . We also predict vn{2 } in Xe+Xe collisions to increase more slowly from central towards peripheral collisions than those in a Pb+Pb system. We find that at 10 ,⋯,50 % centralities v2{2 } is smaller and v3{2 } is larger than in the Pb+Pb system while v4{2 } is of the same magnitude in both systems. We also find that the ratio of flow harmonics in Xe+Xe collisions and in Pb+Pb collisions shows a slight sensitivity to the temperature dependence of the shear-viscosity-to-entropy ratio. As we discuss here, the new nuclear mass-number systematics especially in the flow harmonics serves as a welcome further constraint for describing the space-time evolution of a heavy-ion system and for determining the shear viscosity and other transport properties of strongly interacting matter.

Beta-delayed proton emitter $^{113}Xe$

CERN Document Server

Hagberg, E; Jonson, B; Jørgensen, B; Kugler, E; Mowinckel, T

1973-01-01

The ISOLDE facility at the CERN synchrocyclotron has been used for extending the series of beta -delayed proton emitters in xenon to masses lighter than those previously observed (/sup 115,117/Xe). Owing to the rapid decrease of the yields, experiments with solid-state counters were inconclusive, and instead a new and much more sensitive method based on nuclear emulsions was developed. The mass range 111-114 showed one new activity, /sup 113/Xe, with a half-life of 2.8+or-0.2 sec. From measurements of the track lengths for a total of 1130 protons from /sup 113/Xe it was possible to determine the energy spectrum. The results extend the systematics of beta -strength functions in the light xenon isotopes. (19 refs).

Electron detachment in ion-atom collisions

International Nuclear Information System (INIS)

Vreugd, C. de.

1980-01-01

The electron detachment process that occurs in negative ion-atom collisions is investigated. Differential cross sections were measured for the collisions of F - , Cl - , Br - , I - on He, Ne, Ar, Kr, Xe, Na and K. Electron energy distributions were obtained for some of the systems. (Auth.)

Trapping of negative kaons by metastable states during the atomic cascade in liquid helium

International Nuclear Information System (INIS)

Yamazaki, T.; Aoki, M.; Iwasaki, M.; Hayano, R.S.; Ishikawa, T.; Outa, H.; Takada, E.; Tamura, H.; Sakaguchi, A.

1989-06-01

We observed two distinct peaks, 205 MeV/cπ - and 235 MeV/cμ - , associated with K π2 - and K μ2 - decays at rest, respectively, from negative kaons stopped in liquid helium. These peaks were found to be delayed with respect to the stopping K - , showing that stopped K - mesons of about 2% fraction are trapped in metastable states with an overall lifetime of about 40 nsec. This observation provides a direct evidence for Condo's trapping hypothesis for the at-rest decay components of K - and π - in liquid helium. (author)

Low energy atom-atom collisions

International Nuclear Information System (INIS)

Child, M.S.

1980-01-01

The semiclassical theory of atom-atom potential scattering and of low energy inelastic atom-atom scattering is reviewed. Particular attention is given to the origin and interpretation of rainbow structure, diffraction oscillations and exchange oscillations in the potential scattering differential cross-section, and to the glory structure and symmetry oscillations in the integral cross-section. Available methods for direct inversion of the cross-section data to recover the potential are reviewed in some detail. The theory of non-adiabatic transitions is introduced by a short discussion of interaction mechanisms and of diabetic and adiabatic representations. Analytical S matrix elements are presented for two state curve-crossing (Landau-Zener-Stuckelberg), Demkov and Nikitin models. The relation between Stuckelberg oscillations in the S matrix and in the differential cross-section is discussed in terms of interference between trajectories belonging to two different classical deflection functions. The energy dependences of the inelastic integral cross-section for curve-crossing and Demkov type transitions are also discussed. Finally the theory is reviewed in relation to a recent close-coupled study of fine structure transitions in F( 2 P) + Xe( 2 S) scattering

Determination of the number density of excited and ground Zn atoms during rf magnetron sputtering of ZnO target

Energy Technology Data Exchange (ETDEWEB)

Maaloul, L.; Gangwar, R. K.; Stafford, L., E-mail: luc.stafford@umontreal.ca [Département de Physique, Université de Montréal, Montréal, Québec H3C 3J7 (Canada)

2015-07-15

A combination of optical absorption spectroscopy (OAS) and optical emission spectroscopy measurements was used to monitor the number density of Zn atoms in excited 4s4p ({sup 3}P{sub 2} and {sup 3}P{sub 0}) metastable states as well as in ground 4s{sup 2} ({sup 1}S{sub 0}) state in a 5 mTorr Ar radio-frequency (RF) magnetron sputtering plasma used for the deposition of ZnO-based thin films. OAS measurements revealed an increase by about one order of magnitude of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms by varying the self-bias voltage on the ZnO target from −115 to −300 V. Over the whole range of experimental conditions investigated, the triplet-to-singlet metastable density ratio was 5 ± 1, which matches the statistical weight ratio of these states in Boltzmann equilibrium. Construction of a Boltzmann plot using all Zn I emission lines in the 200–500 nm revealed a constant excitation temperature of 0.33 ± 0.04 eV. In combination with measured populations of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms, this temperature was used to extrapolate the absolute number density of ground state Zn atoms. The results were found to be in excellent agreement with those obtained previously by actinometry on Zn atoms using Ar as the actinometer gas [L. Maaloul and L. Stafford, J. Vac. Sci. Technol., A 31, 061306 (2013)]. This set of data was then correlated to spectroscopic ellipsometry measurements of the deposition rate of Zn atoms on a Si substrate positioned at 12 cm away from the ZnO target. The deposition rate scaled linearly with the number density of Zn atoms. In sharp contrast with previous studies on RF magnetron sputtering of Cu targets, these findings indicate that metastable atoms play a negligible role on the plasma deposition dynamics of Zn-based coatings.

Brain Imaging Using Hyperpolarized 129Xe Magnetic Resonance Imaging.

Science.gov (United States)

Chahal, Simrun; Prete, Braedan R J; Wade, Alanna; Hane, Francis T; Albert, Mitchell S

2018-01-01

Hyperpolarized (HP) 129 Xe magnetic resonance imaging (MRI) is a novel iteration of traditional MRI that relies on detecting the spins of 1 H. Since 129 Xe is a gaseous signal source, it can be used for lung imaging. Additionally, 129 Xe dissolves in the blood stream and can therefore be detectable in the brain parenchyma and vasculature. In this work, we provide detailed information on the protocols that we have developed to image 129 Xe within the brains of both rodents and human subjects. © 2018 Elsevier Inc. All rights reserved.

Hyperpolarized 129Xe as an NMR probe for functional studies

International Nuclear Information System (INIS)

Wolber, J.

2000-01-01

The nuclear spin polarization of 129 Xe can be enhanced by several orders of magnitude using optical pumping techniques, resulting in a dramatic enhancement of the 129 Xe Nuclear Magnetic Resonance (NMR) signal. The 'hyperpolarized' gas can be used for Magnetic Resonance Imaging (MRI) of the void spaces of the lungs after introduction of the gas into the respiratory system. Furthermore, the high solubility of xenon in blood and lipids suggests the use of 129 Xe NMR for studying blood flow, permeability, perfusion and blood volume. Hyperpolarized 129 Xe MRI has the potential of combining the high sensitivity and functional information of radioactive tracer studies with the high spatial and temporal resolution of MRI. The spin-lattice relaxation time T 1 of 129 Xe in blood determines the loss of polarization during transit from the lungs to the tissue of interest. A difference in the relaxation times of xenon in oxygenated and deoxygenated blood could be used as a contrast mechanism in functional Magnetic Resonance Imaging (fMRI). In this thesis, the hyperpolarized 129 Xe T 1 in human blood is measured in vitro as a function of blood oxygenation, and the relevant relaxation mechanisms are discussed. A new and unexpected finding is that the hyperpolarized 129 Xe NMR spectrum in blood is highly sensitive to blood oxygenation. Therefore, hyperpolarized 129 Xe NMR provides a powerful means of measuring blood oxygenation quantitatively and non-invasively. The interaction of xenon with hemoglobin is responsible for an oxygen-dependent shift of the 129 Xe NMR resonance of xenon in red blood cells. Injection delivery of hyperpolarized 129 Xe in solution could be a more efficient method of administrating the gas for functional NMR studies. For this purpose, suitable biocompatible carrier media have been studied. In particular, the use of perfluorocarbon emulsions, which are already in use as blood substitutes, as delivery media for hyperpolarized 129 Xe has been investigates

I-Xe dating of silicate and troilite from IAB iron meteorites

International Nuclear Information System (INIS)

Niemeyer, S.

1979-01-01

Silicate and troilite (FeS) from IAB irons were analyzed by the I-Xe technique. Four IAB silicate samples gave well-defined I-Xe ages [in millions of years relative to Bjurbole: - 3.7 +- 0.3 for Woodbine, -0.7 +- 0.6 for Mundrabilla, + 1.4 +- 0.7 for Copiapo, and +2.6 +- 0.6 for Landes. The ( 129 Xe/ 132 Xe)sub(trapped) ratios are consistent with previous values for chondrites, with the exception of Landes which has an extraordinary trapped ratio of 3.5 +- 0.2. Both analyses of silicate from Pitts gave anomalous I-Xe patterns. Troilite samples were also analyzed: Pitts troilite gave a complex I-Xe pattern, which suggests an age of +17 Myr; Mundrabilla troilite defined a good I-Xe correlation, which after correction for neutron capture on 128 Te gave an age of -10.8 +- 0.7 Myr. Thus, low-melting troilite predates high-melting silicate in Mundrabilla. Abundances of Ga, Ge, and Ni in metal from these meteorites are correlated with I-Xe ages of the silicate; meteorites with older silicates have greater Ni contents. No model easily accounts for this result as well as other properties of IAB irons; nevertheless, these results, taken at face value, favour a nebular formation model. The great age of troilite from Mundrabilla suggests that this troilite formed in a different nebular region from the silicate and metal, and was later mechanically mixed with these other phases. The correlation between the trace elements in the metal and the I-Xe ages of the silicate provides one of the first known instances in which another well-defined meteoritic property correlates with I-Xe ages. In addition, almost all the 129 Xe in Mundrabilla silicate (etched in acid) was correlated with 128 Xe. These two results further support the validity of the I-Xe dating method. (author)

Synthesis and X-ray crystal structure of (OsO(3)F(2))(2)2XeOF(4) and the Raman spectra of (OsO(3)F(2))(infinity), (OsO(3)F(2))(2), and (OsO(3)F(2))(2)2XeOF(4).

Science.gov (United States)

Hughes, Michael J; Mercier, Hélène P A; Schrobilgen, Gary J

2009-05-18

The adduct, (OsO(3)F(2))(2)2XeOF(4), was synthesized by dissolution of the infinite chain polymer, (OsO(3)F(2))(infinity), in XeOF(4) solvent at room temperature followed by removal of excess XeOF(4) under dynamic vacuum at 0 degrees C. Continued pumping at 0 degrees C resulted in removal of associated XeOF(4), yielding (OsO(3)F(2))(2), a new low-temperature phase of OsO(3)F(2). Upon standing at 25 degrees C for 1(1)/(2) h, (OsO(3)F(2))(2) underwent a phase transition to the known monoclinic phase, (OsO(3)F(2))(infinity). The title compounds, (OsO(3)F(2))(infinity), (OsO(3)F(2))(2), and (OsO(3)F(2))(2)2XeOF(4) have been characterized by low-temperature (-150 degrees C) Raman spectroscopy. Crystallization of (OsO(3)F(2))(2)2XeOF(4) from XeOF(4) solution at 0 degrees C yielded crystals suitable for X-ray structure determination. The structural unit contains the (OsO(3)F(2))(2) dimer in which the OsO(3)F(3) units are joined by two Os---F---Os bridges having fluorine bridge atoms that are equidistant from the osmium centers (2.117(5) and 2.107(4) A). The dimer coordinates to two XeOF(4) molecules through Os-F...Xe bridges in which the Xe...F distances (2.757(5) A) are significantly less than the sum of the Xe and F van der Waals radii (3.63 A). The (OsO(3)F(2))(2) dimer has C(i) symmetry in which each pseudo-octahedral OsO(3)F(3) unit has a facial arrangement of oxygen ligands with XeOF(4) molecules that are only slightly distorted from their gas-phase C(4v) symmetry. Quantum-chemical calculations using SVWN and B3LYP methods were employed to calculate the gas-phase geometries, natural bond orbital analyses, and vibrational frequencies of (OsO(3)F(2))(2), (OsO(3)F(2))(2)2XeOF(4), XeOF(4), OsO(2)F(4), and (mu-FOsO(3)F(2))(2)OsO(3)F(-) to aid in the assignment of the experimental vibrational frequencies of (OsO(3)F(2))(2), (OsO(3)F(2))(2)2XeOF(4), and (OsO(3)F(2))(infinity). The vibrational modes of the low-temperature polymeric phase, (OsO(3)F(2))(infinity), have been

LASER RADIATION CHARACTERISTICS (BRIEF COMMUNICATIONS): Conversion of KrCl and XeCl laser radiation to the visible spectral range by stimulated Raman scattering in lead vapor

Science.gov (United States)

Evtushenko, Gennadii S.; Mel'chenko, S. V.; Panchenko, Aleksei N.; Tarasenko, Viktor F.

1990-04-01

Conversion of KrCl and XeCl laser radiation by stimulated Raman scattering was achieved in lead vapor. The KrCl laser radiation was converted into three lines in the visible region at λ = 406, 590, and 723 nm by transitions from both the ground and first excited levels of the lead atom. The conversion efficiency of XeCl laser radiation of low spatial coherence was found to be limited by the activation of a competing nonlinear process.

Collisions of halogen (2P) and rare gas (1S) atoms

International Nuclear Information System (INIS)

Becker, C.H.

1978-12-01

Differential cross sections I (THETA) at several collision energies measured in crossed molecular beam experiments are reported for several combinations of halogen atoms ( 2 P) scattered off rare gas-rare gas atoms ( 1 S 0 ), namely, F + Ne, F + Ar, F + Kr, F + Xe, C1 + Xe. The scattering is described by an elastic model appropriate to Hund's case c coupling. With the use of this model, the X 1/2, I 3/2, and II 1/2 interaction potential energy curves are derived by fitting calculated differential cross sections, based on analytic representations of the potentials, to the data. The F - Xe X 1/2 potential shows a significant bonding qualitatively different than for the other F-rare gases. The I 3/2 and II 1/2 potentials closely resemble the van der Waals interactions of the one electron richer ground state rare gas-rare gas systems. Coupled-channel scattering calculations are carried out for F + Ar, F + Xe, and C1 + Xe using the realistic potential curves derived earlier. The results justify the use of the elastic model, and give additional information on intramultiplet and intermultiplet transitions. The transitions are found to be governed by the crossing of the two Ω = 1/2 potentials in the complex plane. The measured I (theta) and I (THETA) derived from the coupled-channel computations show small oscillations or perturbations (Stueckelberg oscillations) though quantitative agreement is not obtained.The nature of the anomalous F - Xe X 1/2 potential is discussed as is the approximation of a constant spin orbit coupling over the experimentally accessible range of internuclear distances for these open shell molecules. 55 references

A popular metastable omega phase in body-centered cubic steels

Energy Technology Data Exchange (ETDEWEB)

Ping, D.H., E-mail: ping.de-hai@nims.go.jp [National Institute for Materials Science, Sengen 1-2-1, Tsukuba 305-0047 (Japan); Geng, W.T., E-mail: geng@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

2013-05-15

Steel remains to be one of the most common structural materials in the world as human civilization advances from the Iron Age to the ongoing Silicon Age. Our knowledge of its microstructure evolution and structure–performance relationship is nevertheless still incomplete. We report the observation and characterization of a long ignored metastable phase formed in steels with body-centered cubic (bcc) structure using both transmission electron microscopy and density functional theory calculations. This ω phase has a hexagonal structure and coherent interface with the matrix: a{sub ω} = √2 × a{sub bcc} and c{sub ω} = √3/2 × a{sub bcc}. It is 3.6% smaller in volume and 0.18 eV higher in energy than bcc-Fe, with atoms in alternating close- and loose-packed layers couple anti-ferromagnetically. Carbon plays a crucial role in promoting bcc to ω transformation. At a concentration higher than 4 at.% they tend to segregate from the bcc matrix to the ω-phase; at about 14 at.%, they can induce bcc to ω transformation; and finally at 25 at.%, they stabilize the ω phase as ω-Fe{sub 3}C. The ω phase in bcc Fe can serve as sinks for vacancies, H, and He atoms, leading to improved resistance of martensitic steels to irradiation damage. - Highlights: ► A long-ignored metastable ω phase in body-centered cubic (bcc) steel. ► The ω phase has hexagonal structure with lattice parameters a{sub ω} = √2 × a{sub bcc} and c{sub ω} = √3/2 × a{sub bcc}. ► Carbon enrichment is found to play a crucial role on the bcc-to-ω phase transformation. ► The ω phase is strongly related to the martensitic transformation and twinning structure. ► The ω phase in bcc Fe can serve as sinks for vacancies, H, and He atoms.

Diagnostics of microdischarge-integrated plasma sources for display and materials processing

International Nuclear Information System (INIS)

Tachibana, K; Kishimoto, Y; Kawai, S; Sakaguchi, T; Sakai, O

2005-01-01

Two different types of microdischarge-integrated plasma sources have been operated at around the atmospheric pressure range. The discharge characteristics were diagnosed by optical emission spectroscopy (OES), laser absorption spectroscopy (LAS) and microwave transmission (MT) techniques. The dynamic spatiotemporal behaviour of excited atoms was analysed using OES and LAS and the temporal behaviour of the electron density was estimated using the MT method. In Ar and Xe/Ne gases, waveforms of the MT signal followed the current waveform in the rise period and lasted longer according to the recombination losses. However, in He the waveform followed the density of metastable atoms, reflecting the production of a large amount of electrons by the Penning ionization process with impurities. The estimated peak electron density in those plasma sources is of the order of 10 12 cm -3 , and the metastable atom density can reach 10 13 cm -3 . Thus, it is suggested that these sources can be potentially applied to convenient material processing tools of large area operated stably at atmospheric pressure

Origin of anomalous Xe-H in nanodiamond stardust

Energy Technology Data Exchange (ETDEWEB)

Kratz, K. L. [Max-Planck-Institut für Chemie, Otto-Hahn-Institut, D-55128 Mainz, Germany and Fachbereich Chemie, Pharmazie und Geowissenschaften, Universitat Mainz, Mainz (United States); Farouqi, K. [Max-Planck-Institut für Chemie, Otto-Hahn-Institut, D-55128 Mainz, Germany and Zentrum für Astronomie der Universität Heidelberg, D-69120 Heidelberg (Germany); Hallmann, O. [Max-Planck-Institut für Chemie, Otto-Hahn-Institut, D-55128 Mainz (Germany); Pfeiffer, B. [II. Physikalisches Institut, Univ. Giessen, D-35392 Giessen (Germany); Ott, U. [Max-Planck-Institut für Chemie, Otto-Hahn-Institut, D-55128 Mainz (Germany); Univ. of West Hungary, H-9700 Szombathely (Hungary)

2014-05-09

Still today, the nucleosynthesis origin of Xe-H in presolar nanodiamonds is far from understood. Historically possible explanations were proposed by a secondary “neutron-burst” process occurring in the He- or C/O-shells of a type-II supernova (SN-II), which are, however, not fully convincing in terms of modern nucleosynthesis conditions. Therefore, we have investigated Xe isotopic abundance features that may be diagnostic for different versions of a classical, primary r-process in high-entropy-wind (HEW) ejecta of core-collapse SN-II. We report here on parameter tests for non-standard r-process variants, by varying electron abundances (Y{sub e}), ranges of entropies (S) and expansion velocities (V{sub exp}) with their correlated neutron-freezeout times (τ(freeze)) and temperatures (T{sub 9}(freeze)). From this study, we conclude that a best fi to the measured Xe-H abundance ratios {sup i}Xe/{sup 136}Xe can be obtained with the high-S “main” component of a “cold” r-process variant.

Observation of correlated atom pairs in spontaneous four wave mixing of two colliding Bose-Einstein condensates; Observation de paires d'atomes correles au travers de la collision de deux condensats de Bose-Einstein

Energy Technology Data Exchange (ETDEWEB)

Perrin, A

2007-11-15

In this thesis, we report on the observation of pairs of correlated atoms produced in the collision of two Bose-Einstein condensates of metastable helium. Three laser beams perform a Raman transfer which extracts the condensate from the magnetic trap and separates it into two parts with opposite mean momenta. While the condensates propagate, elastic scattering of pairs of atoms occurs, whose momenta satisfy energy and momentum conservation laws. Metastable helium atoms large internal energy allows the use of a position-sensitive, single-atom detector which permits a three-dimensional reconstruction of the scattered atoms'momenta. The statistics of these momenta show correlations for atoms with opposite momenta. The measured correlation volume can be understood from the uncertainty-limited momentum spread of the colliding condensates. This interpretation is confirmed by the observation of the momentum correlation function for two atoms scattered in the same direction. This latter effect is a manifestation of the Hanbury Brown-Twiss effect for indistinguishable bosons. Such a correlated-atom-pair source is a first step towards experiments in which one would like to confirm the pairs'entanglement. (author)

Modified source of a fast neutral atom beam with a controlled energy

International Nuclear Information System (INIS)

Gostev, V.A.; Elakhovskij, D.V.; Khakhaev, A.D.

1980-01-01

A source of a metastable helium atom beam with a controlled energy based on a phenomenon of resonant ion neutralization on the surface of a solid body is described. The neutral particle energy control is carried out by changing ion velocities before their transformation into metastable atoms. The results of experiments with a modified construction of atomic beam source are stated. These experiments were conducted to find the possibilities to control velocities of atoms in a flow as well as to elucidate the peculiarities of operation of a collimator-converter of this construction. Dependences of a halfwidth of the ion velocity distribution function on the ion source parameters have been investigated. The possibility for particle energy control in a collimated flow of fast neutral. atoms has been experimentally shown, it is also shown that a mean value of atom energy in a beam coincides with a value of mean energy of ions from which atoms are produced by the resonant neutralization method; the construction of the source provides the possibility to realize the method of ''overtaking beams'' for neutral atoms and as a result of this to give a possibility for studying atom-atom collisions in a wide energy range at relatively high densities of flows

Half-life of Xe120

Science.gov (United States)

Phillips, A. A.; Andreoiu, C.; Ball, G. C.; Bandyopadhyay, D.; Behr, J. A.; Chupp, T. E.; Finlay, P.; Garrett, P. E.; Grinyer, G. F.; Hackman, G.; Hayden, M. E.; Hyland, B.; Nuss-Warren, S. R.; Pearson, M. R.; Schumaker, M. A.; Smith, M. B.; Svensson, C. E.; Tardiff, E. R.; Valiente-Dobón, J. J.; Warner, T.

2006-08-01

We have measured the half-life of Xe120 using a high-purity germanium (HPGe) detector to monitor the 176, 178, and 762 keV γ rays from Xe120 β+ decay. The result, 46±0.6 min, differs significantly from the value 40±1 min reported by Andersson [Ark. Fys. 28, 37 (1964)]. We have also measured the half-lives of Cs120 and I120 to be 60±0.7 s and 82.1±0.6 min, respectively, both of which are consistent with previous measurements.

Metastable Structures in Cluster Catalysis from First-Principles: Structural Ensemble in Reaction Conditions and Metastability Triggered Reactivity.

Science.gov (United States)

Sun, Geng; Sautet, Philippe

2018-02-28

Reactivity studies on catalytic transition metal clusters are usually performed on a single global minimum structure. With the example of a Pt 13 cluster under a pressure of hydrogen, we show from first-principle calculations that low energy metastable structures of the cluster can play a major role for catalytic reactivity and that hence consideration of the global minimum structure alone can severely underestimate the activity. The catalyst is fluxional with an ensemble of metastable structures energetically accessible at reaction conditions. A modified genetic algorithm is proposed to comprehensively search for the low energy metastable ensemble (LEME) structures instead of merely the global minimum structure. In order to reduce the computational cost of density functional calculations, a high dimensional neural network potential is employed to accelerate the exploration. The presence and influence of LEME structures during catalysis is discussed by the example of H covered Pt 13 clusters for two reactions of major importance: hydrogen evolution reaction and methane activation. The results demonstrate that although the number of accessible metastable structures is reduced under reaction condition for Pt 13 clusters, these metastable structures can exhibit high activity and dominate the observed activity due to their unique electronic or structural properties. This underlines the necessity of thoroughly exploring the LEME structures in catalysis simulations. The approach enables one to systematically address the impact of isomers in catalysis studies, taking into account the high adsorbate coverage induced by reaction conditions.

Multielectron effects in atomic processes

International Nuclear Information System (INIS)

Amusia, M.Ya.; Chernysheva, L.V.

1999-01-01

One demonstrates a prominent role of electron collectivization in atoms and quasi-atomic formations. Paper discusses in detail the approximation of random phases with exchange enabling to take account of these effects. One points out the necessity to go outside the terms of the approximation when studying some processes via combination of the approximation with the theory of disturbances. The results of the recently conducted estimations of cross sections of photoionization of atomic iodine and of its positive and negative ions, Xe + single-electron photoionization, resonance-amplified emission of photons in electron collisions with atoms and quasi-atomic formations, non-dipole corrections to the angular distribution of photoelectrons, probabilities of two electron transitions where the whole amount of energy releases in the form of one photon, illustrate the role of the collective effects [ru

Stereodynamics of Ne(3P2) reacting with Ar, Kr, Xe, and N2

Science.gov (United States)

Zou, Junwen; Gordon, Sean D. S.; Tanteri, Silvia; Osterwalder, Andreas

2018-04-01

Stereodynamics experiments of Ne(3P2) reacting with Ar, Kr, Xe, and N2 leading to Penning and associative ionization have been performed in a crossed molecular beam apparatus. A curved magnetic hexapole was used to state-select and polarize Ne(3P2) atoms which were then oriented in a rotatable magnetic field and crossed with a beam of Ar, Kr, Xe, or N2. The ratio of associative to Penning ionization was recorded as a function of the magnetic field direction for collision energies between 320 cm-1 and 500 cm-1. Reactivities are obtained for individual states that differ only in Ω, the projection of the neon total angular momentum vector on the inter-particle axis. The results are rationalized on the basis of a model involving a long-range and a short-range reaction mechanism. Substantially lower probability for associative ionization was observed for N2, suggesting that predissociation plays a critical role in the overall reaction pathway.

Adsorption properties of fission gases Xe and Kr on pristine and doped graphene: A first principle DFT study

Energy Technology Data Exchange (ETDEWEB)

Vazhappilly, Tijo, E-mail: tijoj@barc.gov.in [Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Ghanty, Tapan K., E-mail: tapang@barc.gov.in [Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094 (India); Jagatap, B.N. [Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

2017-07-15

Graphene has excellent adsorption properties due to large surface area and has been used in applications related to gas sorption and separation. The separation of radioactive noble gases using graphene is an interesting area of research relevant to nuclear waste management. Radioactive noble gases Xe and Kr are present in the off-gas streams from nuclear fission reactors and spent nuclear fuel reprocessing plants. The entrapment of these volatile fission gases is important in the context of nuclear safety. The separation of Xe from Kr is extremely difficult, and energy intensive cryogenic distillation is generally employed. Physisorption based separation techniques using porous materials is a cost effective alternative to expensive cryogenic distillation. Thus, adsorption of noble gases on graphene is relevant for fundamental understanding of physisorption process. The properties of graphene can be tuned by doping and incorporation of defects. In this regard, we study the binding affinity of Xe and Kr in pristine and doped graphene sheets. We employ first principle calculations using density functional theory, corrected for dispersion interactions. The structural parameters obtained from the current study show excellent agreement with the available theoretical and experimental observations on similar systems. Noble gas adsorption energies on pristine graphene match very well with the available literature. Our results show that the binding energy of fission gases Xe and Kr on graphene can be considerably improved through doping the lattice with a heteroatom. - Graphical abstract: The adsorption of radioactive fission gases Xe and Kr on pristine/doped graphene is an interesting topic in the context of nuclear waste management. Previous experimental and computational studies about Xe/Kr adsorption on graphene were limited to only on pristine graphene. The doping by hetero atom changes the electronic properties of graphene and creates active sites in the lattice. Based

Measurement of the azimuthal anisotropy of charged particle production in Xe+Xe collisions at $\\sqrt{s_{\\mathrm{NN}}}$=5.44~TeV with the ATLAS detector

CERN Document Server

The ATLAS collaboration

2018-01-01

This note describes the measurement of flow harmonics $v_2$--$v_5$ in Xe+Xe collisions at $\\sqrt{s_{\\mathrm{NN}}}$=5.44~TeV performed using the ATLAS detector at the LHC. The measurements are performed using multi-particle correlations involving 2, 4 and 6 particles and the Scalar Product technique. Measurements of the centrality and $p_{\\mathrm{T}}$ dependence of the $v_n$ are presented. Comparisons of the measured $v_n$ to previous measurements for Pb+Pb collisions at $\\sqrt{s_{\\mathrm{NN}}}$=5.02~TeV are also presented. The Xe+Xe $v_n$ are observed to be larger than the Pb+Pb $v_n$ for $n$=2,3 and $4$ in the most central events, but with decreasing centrality or increasing harmonic order $n$, the Xe+Xe $v_n$ become smaller than the Pb+Pb $v_n$. The Xe+Xe and Pb+Pb comparisons are also shown as a function of the mean number of participants $\\langle N_\\text{part} \\rangle$, and the 4-particle cumulants for higher-order harmonics -- $v_3\\{4\\}$ and $v_4\\{4\\}$ -- are found to scale better with $\\langle N_\\text{p...

EUV emission from Kr and Xe capillary discharge plasmas

International Nuclear Information System (INIS)

Juschkin, L.; Ellwi, S.; Kunze, H-J.; Chuvatin, A.; Zakharov, S.V.

2002-01-01

Kr and Xe plasmas are very intensive emitters in the spectral range of 100-150 A, which is relevant for a number of applications (for example microlithography). We present investigations of the extreme utraviolet (EUV) emission from a slow capillary discharge with Kr and Xe fillings. The emission of Kr ions (Kr VIII to Kr XI) within the range of 70-150 A consists of three bands of lines of about 10 A width with maxima at 116, 103 and 86 A. Xe emission bands of about 15 A width have their maxima at 136 and 115 A (Xe IX to Xe XII). The radiation duration in this spectral range is ∼150 ns for both elements. At the optimum conditions, the Kr emission at 103 A is 2-3 times more intense than the Xe emission at 136 A. The measured spectral energy of Kr radiation is about 0.1 J sr -1 A -1 . Experimental results are compared with numerical modellings of the dynamics and emission of the capillary discharge plasma, which enables the determination of plasma parameters and the future use of the codes as additional instruments for plasma diagnostics. (author)

Spectroscopy of highly ionized atoms

International Nuclear Information System (INIS)

Livingston, A.E.

1987-01-01

The atomic structure and decay characteristics of excited states in multiply ionized atoms represent a fertile testing ground for atomic calculations ranging from accurate ab initio theory for few-electron systems to practical semi-empirical approaches for many-electron species. Excitation of fast ions by thin foils generally produces the highest ionization stages for heavy ions in laboratory sources. The associated characteristics of spectroscopic purity and high time resolution provide unique capabilities for studying the atomic properties of highly-ionized atoms. This report is limited to a brief discussion of three classes of atomic systems that are experiencing current theoretical and experimental interest: precision structure of helium-like ions, fine structure of doubly-excited states, and lifetimes of metastable states. Specific measurements in each of these types of systems are mentioned, with emphasis on the relation to studies involving slow, highly-charged ions

Metastable Supersymmetry Breaking in a Cooling Universe

International Nuclear Information System (INIS)

Kaplunovsky, Vadim S.

2007-01-01

I put metastable supersymmetry breaking in a cosmological context. I argue that under reasonable assumptions, the cooling down early Universe favors metastable SUSY-breaking vacua over the stable supersymmetric vacua. To illustrate the general argument, I analyze the early-Universe history of the Intriligator-Seiberg-Shih model

Xe isotope detection and discrimination using beta spectroscopy with coincident gamma spectroscopy

Science.gov (United States)

Reeder, P. L.; Bowyer, T. W.

1998-02-01

Beta spectroscopic techniques show promise of significant improvements for a beta-gamma coincidence counter that is part of a system for analyzing Xe automatically separated from air. The previously developed counting system for 131mXe, 133mXe, 133gXe, and 135gXe can be enhanced to give additional discrimination between these Xe isotopes by using the plastic scintillation sample cell as a beta spectrometer to resolve the conversion electron peaks. The automated system will be a key factor in monitoring the Comprehensive Test Ban Treaty.

On a metastable vacuum burning phenomenon

International Nuclear Information System (INIS)

Berezin, V.A.; Tkachev, I.I.; Kuzmin, V.A.; AN SSSR, Moscow. Inst. Yadernykh Issledovanij)

1983-02-01

Equations of motion of an interface between two phases with arbitrary equations of state are obtained. It is found that there may take place a process of metastable vacuum burning. It is shown that under some conditions the process of the new phase bubble expansion is described by the detonation wave equations. Possible cosmological consequences of the metastable phase burning effect are briefly discussed. (author)

Fluorescence measurement of atomic oxygen concentration in a dielectric barrier discharge

Science.gov (United States)

Dvořák, P.; Mrkvičková, M.; Obrusník, A.; Kratzer, J.; Dědina, J.; Procházka, V.

2017-06-01

Concentration of atomic oxygen was measured in a volume dielectric barrier discharge (DBD) ignited in mixtures of Ar + O2(+ H2) at atmospheric pressure. Two-photon absorption laser induced fluorescence (TALIF) of atomic oxygen was used and this method was calibrated by TALIF of Xe in a mixture of argon and a trace of xenon. The calibration was performed at atmospheric pressure and it was shown that quenching by three-body collisions has negligible effect on the life time of excited Xe atoms. The concentration of atomic oxygen in the DBD was around 1021 m-3 and it was stable during the whole discharge period. The concentration did not depend much on the electric power delivered to the discharge provided that the power was sufficiently high so that the visible discharge filled the whole reactor volume. Both the addition of hydrogen or replacing of argon by helium led to a significant decrease of atomic oxygen concentration. The TALIF measurements of O concentration levels in the DBD plasma performed in this work are made use of e.g. in the field analytical chemistry. The results contribute to understanding the processes of analyte hydride preconcentration and subsequent atomization in the field of trace element analysis where DBD plasma atomizers are employed.

Xe isotopic abundances in enstatite meteorites and relations to other planetary reservoirs

International Nuclear Information System (INIS)

Lee, Jee-Yon; Marti, Kurt; Wacker, John F.

2009-01-01

This paper describes the interpretation of xenon that was measured in the Abee meteorite. Reported Xe isotopic abundances in enstatite chondrites (EC's) show some variability, and this makes comparisons to other solar system reservoirs rather difficult. In contrast, we find uniform Xe isotopic abundances in the EC chondrite Abee for a variety of clasts, except for 128 Xe and 129 Xe, the isotopes affected by neutron capture in I and by extinct 129 I. We report averages for the studied clasts which are consistent within error limits with OC-Xe and with the Q-Xe signature. On the other hand, the elemental abundance ratios Ar/Xe are variable between clasts. A strongly reducing environment which is indicated for enstatite meteorites was generally assumed to be consistent with conditions existing in the early inner solar system. Xe isotopic abundances in SNC meteorites from Mars and also those in some terrestrial wells show that distinct isotopic reservoirs coexisted on the same planets. In particular, the Xe isotopic signatures in terrestrial well gases show the presence of a minor distinct component in two of the reported four well gases. These authors suggested that the extra component represents solar Xe, but we show that also a meteoritic xenon reservoir of the Abee-Xe structure is an option. The reported Xe data in Ar-rich (subsolar) EC's show isotopic abundances slightly lighter than those in Abee-Xe, but the relative abundances of Ar, Kr, and Xe indicate only a minor component of elementally unfractionated solar Xe. The elemental ratios suggest rather a different origin for these gases: the loading of solar particles into grain surfaces during exposure at elevated temperatures during accretion of matter in the inner solar system. A model of this type was suggested for the accretion of gases now observed in the atmosphere on Venus. We note that disks of crystalline silicates (including enstatite and olivine) have been observed in T Tauri stars during their early

Stimulated transitions in resonant atom Majorana mixing

Science.gov (United States)

Bernabéu, José; Segarra, Alejandro

2018-02-01

Massive neutrinos demand to ask whether they are Dirac or Majorana particles. Majorana neutrinos are an irrefutable proof of physics beyond the Standard Model. Neutrinoless double electron capture is not a process but a virtual Δ L = 2 mixing between a parent A Z atom and a daughter A ( Z - 2) excited atom with two electron holes. As a mixing between two neutral atoms and the observable signal in terms of emitted two-hole X-rays, the strategy, experimental signature and background are different from neutrinoless double beta decay. The mixing is resonantly enhanced for almost degeneracy and, under these conditions, there is no irreducible background from the standard two-neutrino channel. We reconstruct the natural time history of a nominally stable parent atom since its production either by nature or in the laboratory. After the time periods of atom oscillations and the decay of the short-lived daughter atom, at observable times the relevant "stationary" states are the mixed metastable long-lived state and the non-orthogonal short-lived excited state, as well as the ground state of the daughter atom. We find that they have a natural population inversion which is most appropriate for exploiting the bosonic nature of the observed atomic transitions radiation. Among different observables of the atom Majorana mixing, we include the enhanced rate of stimulated X-ray emission from the long-lived metastable state by a high-intensity X-ray beam: a gain factor of 100 can be envisaged at current XFEL facilities. On the other hand, the historical population of the daughter atom ground state can be probed by exciting it with a current pulsed optical laser, showing the characteristic absorption lines: the whole population can be excited in a shorter time than typical pulse duration.

Dependences of the van der Waals atom-wall interaction on atomic and material properties

International Nuclear Information System (INIS)

Caride, A.O.; Klimchitskaya, G.L.; Mostepanenko, V.M.; Zanette, S.I.

2005-01-01

The 1%-accurate calculations of the van der Waals interaction between an atom and a cavity wall are performed in the separation region from 3 nm to 150 nm. The cases of metastable He * and Na atoms near metal, semiconductor, and dielectric walls are considered. Different approximations to the description of wall material and atomic dynamic polarizability are carefully compared. The smooth transition to the Casimir-Polder interaction is verified. It is shown that to obtain accurate results for the atom-wall van der Waals interaction at short separations with an error less than 1% one should use the complete optical-tabulated data for the complex refractive index of the wall material and the accurate dynamic polarizability of an atom. The obtained results may be useful for the theoretical interpretation of recent experiments on quantum reflection and Bose-Einstein condensation of ultracold atoms on or near surfaces of different kinds

Metastable enhancement of C+ and O+ capture reactions

International Nuclear Information System (INIS)

Thomas, E.W.

1992-01-01

The project is devoted to the study of charge transfer neutralization of Carbon and oxygen ions in H and H 2 gases at energies from 10 to 500 eV. A major motivation was to provide cross section data to support analysis of edge plasmas in Tokamak Fusion devices. The first objective was to measure cross sections for metastable excited singly charged ions separately from the cross sections for ground state ions. Previously published values are confusing because the beams used included unknown fractions of metastables and these metastables have cross sections greatly different from the ground states. The program was fully accomplished, metastable cross sections were found to be over an order of magnitude greater than ones for the ground state and existing discrepancies in the literature were resolved. Considerable effort was devoted to the design and operation of ion source configurations were the metastable content of the ion beam was known. Subsequently study progressed to the neutralization of multiply charged C and 0 ions in the same targets. First there has been a need to develop ion sources which can produce useful beams of multiply charged species. This has now been accomplished. The intent is to use these sources for the measurement of cross sections with again an attempt to differentiate between the behavior of ground and metastably excited species

Metastable and unstable cellular solidification of colloidal suspensions

Science.gov (United States)

Deville, Sylvain; Maire, Eric; Bernard-Granger, Guillaume; Lasalle, Audrey; Bogner, Agnès; Gauthier, Catherine; Leloup, Jérôme; Guizard, Christian

2009-12-01

Colloidal particles are often seen as big atoms that can be directly observed in real space. They are therefore becoming increasingly important as model systems to study processes of interest in condensed-matter physics such as melting, freezing and glass transitions. The solidification of colloidal suspensions has long been a puzzling phenomenon with many unexplained features. Here, we demonstrate and rationalize the existence of instability and metastability domains in cellular solidification of colloidal suspensions, by direct in situ high-resolution X-ray radiography and tomography observations. We explain such interface instabilities by a partial Brownian diffusion of the particles leading to constitutional supercooling situations. Processing under unstable conditions leads to localized and global kinetic instabilities of the solid/liquid interface, affecting the crystal morphology and particle redistribution behaviour.

Atomic probes of surface structure and dynamics

International Nuclear Information System (INIS)

Heller, E.J.; Jonsson, H.

1992-01-01

Progress for the period Sept. 15, 1992 to Sept. 14, 1993 is discussed. Semiclassical methods that will allow much faster and more accurate three-dimensional atom--surface scattering calculations, both elastic and inelastic, are being developed. The scattering of He atoms from buckyballs is being investigated as a test problem. Somewhat more detail is given on studies of He atom scattering from defective Pt surfaces. Molecular dynamics simulations of He + and Ar + ion sputtering of Pt surfaces are also being done. He atom scattering from Xe overlayers on metal surfaces and the thermalized dissociation of H 2 on Cu(110) are being studied. (R.W.R.) 64 refs

Metastable superconducting alloys

International Nuclear Information System (INIS)

Johnson, W.L.

1978-07-01

The study of metastable metals and alloys has become one of the principal activities of specialists working in the field of superconducting materials. Metastable crystalline superconductors such as the A15-type materials have been given much attention. Non-crystalline superconductors were first studied over twenty years ago by Buckel and Hilsch using the technique of thin film evaporation on a cryogenic substrate. More recently, melt-quenching, sputtering, and ion implantation techniques have been employed to produce a variety of amorphous superconductors. The present article presents a brief review of experimental results and a survey of current work on these materials. The systematics of superconductivity in non-crystalline metals and alloys are described along with an analysis of the microscopic parameters which underlie the observed trends. The unique properties of these superconductors which arise from the high degree of structural disorder in the amorphous state are emphasized

Progress in short period multilayer coatings for water window applications

International Nuclear Information System (INIS)

Gullikson, E.M.; Salmassi, F.; Aquila, A.L.; Dollar, F.

2006-01-01

Absolute photoionization cross-section measurements for a mixture of ground and metastable states of Xe4+, Xe5+, and Xe6+ are reported in the photon energy range of 4d-nf transitions, which occur within or adjacent to the 13.5 nm window for extreme ultraviolet lithography light source development. The reported values allow the quantification of opacity effects in xenon plasmas due to these 4d-4f autoionizing states. The oscillator strengths for the 4d-4f and 4d-5f transitions in Xeq+ (q=1-6) ions are calculated using nonrelativistic Hartree-Fock and random phase approximations. These are compared with published experimental values for Xe+ to Xe3+ and with the values obtained from the present experimental cross-section measurements for Xe4+ to Xe6+. The calculations assisted in the determination of the metastable content in the ion beams for Xe5+T and Xe6+. The experiments were performed by merging a synchrotron photon beam generated by an undulator beamline of the Advanced Light Source with an ion beam produced by an electron cyclotron resonance ion source

XeCl Excimer Laser with Three- and Four-Component Mixture of Active Gases

International Nuclear Information System (INIS)

Iwanejko, L.; Pokora, L.

1998-01-01

Selected results of investigations of a XeCl excimer laser employing a new type (four-component)of mixture of gases, He-Kr:Xe-HCl, are presented. The mixture includes, instead of Xe, a mixture of not-separated Kr and Xe gases, much less expensive than pure xenon. A comparison of durations and energies of pulses generated in the XeCl excimer laser using three- or four-component gaseous active medium (He-Xe-HCl or He-Kr:Xe-HCl) is made. The investigations have been carried out with the use of a laser system with UV preionization and self sustained pumping discharge. (author)

Variable energy positron beam study of Xe-implanted uranium oxide

International Nuclear Information System (INIS)

Djourelov, Nikolay; Marchand, Benoît; Marinov, Hristo; Moncoffre, Nathalie; Pipon, Yves; Nédélec, Patrick; Toulhoat, Nelly; Sillou, Daniel

2013-01-01

Doppler broadening of annihilation gamma-line combined with a slow positron beam was used to measure the momentum density distribution of annihilating pair in a set of sintered UO 2 samples. The influence of surface polishing, of implantation with 800-keV 136 Xe 2+ at fluences of 1 × 10 15 and 1 × 10 16 Xe cm −2 , and of annealing were studied by following the changes of the momentum distribution shape by means of S and W parameters. The program used for this purpose was VEPFIT. At the two fluences in the stoichiometric as-implanted UO 2 , formation of Xe bubbles was not detected. The post-implantation annealing and over-stoichiometry in the as-implanted sample caused Xe precipitation and formation of Xe bubbles.

Lifetime measurements in Crsub(I) by laser excitation from the metastable states

International Nuclear Information System (INIS)

Kwiatkowski, M.; Micali, G.; Werner, K.; Zimmermann, P.

1981-01-01

A combination of collisional and laser excitation was used to measure radiative lifetimes in Cr I. By a discharge an atomic beam of metastable atoms in the 3d 5 4sa 5 S, a 5 G, b 5 D, a 3 I, b 1 I and 3d 4 4s 2 a 5 D terms was produced. Spatially separated from the place of collisional excitation laser radiation selectively populated levels belonging to the 3d 5 4p z 5 P, y 5 P, u 5 F, u 5 D, x 3 I, y 1 I, 3d 5 5pz 5 G and 3d 4 4s4px 5 G terms. Time-resolved observation of the reemitted resonance fluorescence yielded the lifetimes of 28 levels. The values are compared with other experimental and theoretical results. (orig.)

Test of Lorentz symmetry with a 3He/129Xe clock-comparison experiment

International Nuclear Information System (INIS)

Gemmel, Claudia

2011-01-01

The minimal Standard Model Extension (SME) of Kostelecky and coworkers, which parametrizes the general treatment of CPT- and Lorentz invariance violation, predicts sidereal modulations of atomic transition frequencies as the Earth rotates relative to a Lorentz-violating background field. One method to search for these modulations is the so-called clock-comparison experiment, where the frequencies of co-located clocks are compared as they rotate with respect to the fixed stars. In this work an experiment is presented where polarized 3 He and 129 Xe gas samples in a glass cell serve as clocks, whose nuclear spin precession frequencies are detected with the help of highly sensitive SQUID sensors inside a magnetically shielded room. The unique feature of this experiment is the fact that the spins are precessing freely, with transverse relaxation times T * 2 of up to 4.4 h for 129 Xe and 14.1 h for 3 He. To be sensitive to Lorentz-violating effects, the influence of external magnetic fields is canceled via the weighted 3 He/ 129 Xe phase difference, ΔΦ=Φ he -(γ he )/(γ xe ) Φ xe . The Lorentz-violating SME parameters for the neutron, b n X and b n Y , are determined out of a χ 2 fit on the phase difference data of 7 spin precession measurements of 12 to 16 hours length. The piecewise defined fit model contains a sine and a cosine term to describe the sidereal modulation, as well as 7 offset terms, 7 linear terms and 7 . 2 exponential terms decreasing with T * 2,he and T * 2,xe , which are assigned to the respective measurement. The linear term in the weighted phase difference mainly arises from deviations of the gyromagnetic ratios from their literature values due to chemical shifts, while the exponential terms reflect the phase shifts resulting from demagnetization fields in the non-ideally spherical sample cell. The result of the χ 2 fit constrains the parameter b n perpendicular to =√((b n X ) 2 +(b n Y ) 2 ) to be -32 GeV at the 95% confidence level. This

Evaluation of reactivity and Xe behavior during daily load following operation

International Nuclear Information System (INIS)

Sakamoto, Yasunori; Araki, Tsuneyasu; Yamamoto, Fumiaki

1992-01-01

A boiling water reactor (BWR) has an excellent load following capability provided by a core flow control, which is used for changing a reactor power level and for compensating the subsequent Xe concentration change. The core characteristics during load following operations are investigated in detail, using our reactor core simulator. Comparisons of changes of the Doppler reactivity, the void reactivity and the Xe reactivity during transients are performed. Also the features of Xe transient during load following operations are shown. It has been shown that the core flow change required to compensate the Xe reactivity change produces much greater change of the void reactivity than that required for power level changes, and that the resulting local power change in the lower part of the core is greater than that in the upper part, because the Xe concentration change in the lower part is hardly compensated by the core flow control. Also the effects of power level changes, cycle patterns, and initial concentration of Xe and I on the Xe transient behavior have been investigated. (author)

Observation of correlated atom pairs in spontaneous four wave mixing of two colliding Bose-Einstein condensates

International Nuclear Information System (INIS)

Perrin, A.

2007-11-01

In this thesis, we report on the observation of pairs of correlated atoms produced in the collision of two Bose-Einstein condensates of metastable helium. Three laser beams perform a Raman transfer which extracts the condensate from the magnetic trap and separates it into two parts with opposite mean momenta. While the condensates propagate, elastic scattering of pairs of atoms occurs, whose momenta satisfy energy and momentum conservation laws. Metastable helium atoms large internal energy allows the use of a position-sensitive, single-atom detector which permits a three-dimensional reconstruction of the scattered atoms'momenta. The statistics of these momenta show correlations for atoms with opposite momenta. The measured correlation volume can be understood from the uncertainty-limited momentum spread of the colliding condensates. This interpretation is confirmed by the observation of the momentum correlation function for two atoms scattered in the same direction. This latter effect is a manifestation of the Hanbury Brown-Twiss effect for indistinguishable bosons. Such a correlated-atom-pair source is a first step towards experiments in which one would like to confirm the pairs'entanglement. (author)

Desensitization and recovery of metastable intermolecular composites

Science.gov (United States)

Busse, James R [South Fork, CO; Dye, Robert C [Los Alamos, NM; Foley, Timothy J [Los Alamos, NM; Higa, Kelvin T [Ridgecrest, CA; Jorgensen, Betty S [Jemez Springs, NM; Sanders, Victor E [White Rock, NM; Son, Steven F [Los Alamos, NM

2010-09-07

A method to substantially desensitize a metastable intermolecular composite material to electrostatic discharge and friction comprising mixing the composite material with an organic diluent and removing enough organic diluent from the mixture to form a mixture with a substantially putty-like consistency, as well as a concomitant method of recovering the metastable intermolecular composite material.

Dynamical SUSY breaking in meta-stable vacua

International Nuclear Information System (INIS)

Intriligator, Kenneth; Seiberg, Nathan; Shih, David

2006-01-01

Dynamical supersymmetry breaking in a long-lived meta-stable vacuum is a phenomenologically viable possibility. This relatively unexplored avenue leads to many new models of dynamical supersymmetry breaking. Here, we present a surprisingly simple class of models with meta-stable dynamical supersymmetry breaking: N = 1 supersymmetric QCD, with massive flavors. Though these theories are strongly coupled, we definitively demonstrate the existence of meta-stable vacua by using the free-magnetic dual. Model building challenges, such as large flavor symmetries and the absence of an R-symmetry, are easily accommodated in these theories. Their simplicity also suggests that broken supersymmetry is generic in supersymmetric field theory and in the landscape of string vacua

Atomic emission spectroscopy

Science.gov (United States)

Andrew, K. H.

1975-01-01

The relationship between the Slater-Condon theory and the conditions within the atom as revealed by experimental data was investigated. The first spectrum of Si, Rb, Cl, Br, I, Ne, Ar, and Xe-136 and the second spectrum of As, Cu, and P were determined. Methods for assessing the phase stability of fringe counting interferometers and the design of an autoranging scanning system for digitizing the output of an infrared spectrometer and recording it on magnetic tape are described.

I-Xe dating of silicate and troilite from IAB iron meteorites

International Nuclear Information System (INIS)

Niemeyer, S.

1978-01-01

The IAB iron meteorites may be related to the chondrites; siderophile elements in the metal matrix have chondritic abundances, and the abundant silicate inclusions are chondritic both in mineralogy and in chemical composition. Silicate and troilite (FeS) and IAB irons were analyzed by the I-Xe technique. Four IAB silicate samples gave well-defined I-Xe ages [in millions of years relative to Bjurboele; the monitor error (+-2.5 m.y.) is not included]: -3.7 +- 0.3 for Woodbine, -0.7 +- 0.6 for Mundrabilla, +1.4 +- 0.7 for Copiapo, and +2.6 +- 0.6 for Landes. The ( 129 Xe/ 132 Xe)/sub trapped/ ratios are consistent with previous values for chondrites, with the exception of Landes which has an extraordinary trapped ratio of 3.5 +- 0.2. Both analyses of silicate from Pitts gave anomalous I-Xe patterns: intermediate-temperature points defined good correlations but higher-temperature (greater than or equal to 1400 0 C) points lay above (extra 129 Xe) these lines. The two correlations have different slopes, so it cannot be assigned a definite I-Xe age to Pitts silicate. Troilite samples from Mundrabilla and Pitts were also analyzed: Pitts troilite gave a complex I-Xe pattern, which suggests an age of +17 m.y.; Mundrabilla troilite defined a good I-Xe correlation, which after correction for neutron capture on 128 Te an age of -10.8 +- 0.7 m.y. Thus, surprisingly, low-melting troilite substantially predates high-melting silicate in Mundrabilla. Abundances of Ga, Ge, and Ni in metal from these meteorites are correlated with I-Xe ages of the silicate (referred to henceforth as the metal-silicate correlation). After exploring possible relationships between the I-Xe ages and other properties of the IAB group, it was concluded that the metal-silicate correlation, the old Mundrabilla troilite, and other results favor a nebular formation model (e.g. Wasson, 1970a)

Xe/Kr Selectivity Measurements using AgZ-PAN at Various Temperatures

International Nuclear Information System (INIS)

Garn, Troy Gerry; Greenhalgh, Mitchell Randy; Watson, Tony Leroy

2015-01-01

In preparation for planned FY-15 Xe/Kr multi-column testing, a series of experiments were performed to determine the selectivity of Xe over Kr using the silver converted mordenite-polyacrylonitrile (AgZ-PAN) sorbent. Results from these experiments will be used for parameter selection guidelines to define test conditions for Kr gas capture purity evaluations later this year. The currently configured experimental test bed was modified by installing a new cooling apparatus to permit future multi-column testing with independent column temperature control. The modified test bed will allow for multi-column testing to facilitate a Xe separation followed by a Kr separation using engineered form sorbents. Selectivity experiments were run at temperatures of 295, 250 and 220 K. Two feed gas compositions of 1000 ppmv Xe, 150 ppmv Kr in either a He or an air balance were used. AgZ-PAN sorbent selectivity was calculated using Xe and Kr capacity determinations. AgZ-PAN sorbent selectivities for Xe over Kr of 72 were calculated at room temperature (295 K) using the feed gas with a He balance and 34 using the feed gas with an air balance. As the test temperatures were decreased the selectivity of Xe over Kr also decreased due to an increase in both Xe and Kr capacities. At 220 K, the sorbent selectivities for Xe over Kr were 22 using the feed gas with a He balance and 28 using the feed gas with an air balance. The selectivity results indicate that AgZ-PAN used in the first column of a multi-column configuration will provide adequate partitioning of Xe from Kr in the tested temperature range to produce a more pure Kr end product for collection.

Effect of Xe ion (167 MeV) irradiation on polycrystalline SiC implanted with Kr and Xe at room temperature

International Nuclear Information System (INIS)

Hlatshwayo, T T; Kuhudzai, R J; Njoroge, E G; Malherbe, J B; O’Connell, J H; Skuratov, V A; Msimanga, M

2015-01-01

The effect of swift heavy ion (Xe 167 MeV) irradiation on polycrystalline SiC individually implanted with 360 keV Kr and Xe ions at room temperature to fluences of 2  ×  10 16 cm −2 and 1  ×  10 16 cm −2 respectively, was investigated using transmission electron microscopy (TEM), Raman spectroscopy and Rutherford backscattering spectrometry (RBS). Implanted specimens were each irradiated with 167 MeV Xe +26 ions to a fluence of 8.3  ×  10 14 cm −2 at room temperature. It was observed that implantation of 360 keV Kr and Xe ions individually at room temperature amorphized the SiC from the surface up to a depth of 186 and 219 nm respectively. Swift heavy ion (SHI) irradiation reduced the amorphous layer by about 27 nm and 30 nm for the Kr and Xe samples respectively. Interestingly, the reduction in the amorphous layer was accompanied by the appearance of randomly oriented nanocrystals in the former amorphous layers after SHI irradiation in both samples. Previously, no similar nanocrystals were observed after SHI irradiations at electron stopping powers of 33 keV nm −1 and 20 keV nm −1 to fluences below 10 14 cm −2 . Therefore, our results suggest a fluence threshold for the formation of nanocrystals in the initial amorphous SiC after SHI irradiation. Raman results also indicated some annealing of radiation damage after swift heavy ion irradiation and the subsequent formation of small SiC crystals in the amorphous layers. No diffusion of implanted Kr and Xe was observed after swift heavy ion irradiation. (paper)

Observation of correlated atom pairs in spontaneous four wave mixing of two colliding Bose-Einstein condensates; Observation de paires d'atomes correles au travers de la collision de deux condensats de Bose-Einstein

Energy Technology Data Exchange (ETDEWEB)

Perrin, A

2007-11-15

In this thesis, we report on the observation of pairs of correlated atoms produced in the collision of two Bose-Einstein condensates of metastable helium. Three laser beams perform a Raman transfer which extracts the condensate from the magnetic trap and separates it into two parts with opposite mean momenta. While the condensates propagate, elastic scattering of pairs of atoms occurs, whose momenta satisfy energy and momentum conservation laws. Metastable helium atoms large internal energy allows the use of a position-sensitive, single-atom detector which permits a three-dimensional reconstruction of the scattered atoms'momenta. The statistics of these momenta show correlations for atoms with opposite momenta. The measured correlation volume can be understood from the uncertainty-limited momentum spread of the colliding condensates. This interpretation is confirmed by the observation of the momentum correlation function for two atoms scattered in the same direction. This latter effect is a manifestation of the Hanbury Brown-Twiss effect for indistinguishable bosons. Such a correlated-atom-pair source is a first step towards experiments in which one would like to confirm the pairs'entanglement. (author)

Using ion production to monitor the birth and death of a metastable helium Bose-Einstein condensate

International Nuclear Information System (INIS)

Seidelin, S; Sirjean, O; Gomes, J Viana; Boiron, D; Westbrook, C I; Aspect, A

2003-01-01

We discuss observations of the ion flux from a cloud of trapped 2 3 S 1 metastable helium atoms. Both Bose-Einstein condensates (BEC) and thermal clouds were investigated. The ion flux is compared with time-of-flight observations of the expanded cloud. We show data concerning BEC formation and decay, as well as measurements of two-and three-body ionization rate constants. We also discuss possible improvements and extensions of our results

Shock disturbance of the I-Xe system

International Nuclear Information System (INIS)

Caffee, M.W.; Hohenberg, C.M.; Podosek, F.A.; Swindle, T.D.

1982-01-01

Three separate samples of the meteorite Bjurbole were artificially shocked at pressures of 70 kb, 200 kb, and 400 kb. Analysis of xenon released in stepwise heating shows that the I-Xe system of the 400 kb sample is substantially altered by the shock loading, and it is no longer possible to infer an age or trapped xenon composition for that sample. The 200-kb and 70-kb samples display isotopic structures progressively less altered demonstrating the gradations in shock disturbance likely to be found in natural systems. Interpretations of the I-Xe and Ar-40-Ar-39 systems for several naturally shocked meteorites are also presented. New data for Arapahoe do not confirm the previously reported age and trapped xenon composition, demonstrating instead that its I-Xe structure has been strongly disturbed by shock

Photoionization of xenon below the atomic ionization potential

International Nuclear Information System (INIS)

Laporte, P.; Saile, V.; Reininger, R.; Asaf, U.; Steinberger, I.T.

1982-10-01

Experiments using monochromated synchrotron radiation revealed that for densities of the order of 10 19 atoms/cm 3 and more xenon exhibits a continuous photoresponse excitation spectrum below the atomic ionization potential (12.12 eV). The lower limit of the continuum is at about 11.10 eV, the energy difference between the ground state of the molecular ion Xe 2+ and that of the free atom. This is attributed to the Hornbeck-Molnar process occurring at the line wings as well as at the line centres. Dips appearing in the continuum very near to positions of atomic lines are discussed invoking the quasi-static theory. (orig.)

Excess 129Xe in terrestrial samples: A non-primordial hypothesis

International Nuclear Information System (INIS)

Caffee, M.W.; Hudson, G.B.

1987-03-01

Excesses of 129 Xe relative to the isotopic composition in air are observed in some terrestrial samples. Traditionally these 129 Xe excesses have been thought to be related to 129 I that was present in abundance in the early solar system. We propose an alternative hypothesis to explain terrestrial 129 Xe excesses based on the production of 129 I from the spontaneous fission of 238 U

Unified quantum theory of elastic and inelastic atomic scattering from a physisorbed monolayer solid

DEFF Research Database (Denmark)

Bruch, L. W.; Hansen, Flemming Yssing; Dammann, Bernd

2017-01-01

A unified quantum theory of the elastic and inelastic scattering of low energy He atoms by a physisorbed monolayer solid in the one-phonon approximation is given. It uses a time-dependent wave packet with phonon creation and annihilation components and has a self-consistent feedback between...... the wave functions for elastic and inelastic scattered atoms. An attenuation of diffraction scattering by inelastic processes thus is inherent in the theory. The atomic motion and monolayer vibrations in the harmonic approximation are treated quantum mechanically and unitarity is preserved. The evaluation...... of specific one-phonon events includes contributions from diffuse inelastic scattering in other phonon modes. Effects of thermally excited phonons are included using a mean field approximation. The theory is applied to an incommensurate Xe/Pt(111) monolayer (incident energy Ei = 4-16 meV), a commensurate Xe...

Luminescent Characteristics of a Pulsed Discharge Plasma in Xe-KBr Mixture

Science.gov (United States)

Heneral, A. A.; Zhmenyak, Y. V.

2018-03-01

A mixture of xenon with a nontoxic halogen carrier Xe-KBr is used to create a plasma radiation source at the 282-nm transition of the XeBr* molecule excited by a high-voltage pulsed-periodic discharge. The luminescence spectra of the plasma of a longitudinal pulsed-periodic discharge in the Xe-KBr mixture at low pressures are studied experimentally. The most intense UV bands of exciplex XeBr* molecules are recorded in the spectral range of 250-350 nm. The spectral, temporal, and energetic characteristics of the radiation source are presented, as well as the dependence of the XeBr* exciplex molecule formation efficiency on the discharge excitation conditions. The optimal conditions for the excitation of UV radiation in the pulsed-periodic discharge plasma are determined.

Xe isotopic constraints on cycling of deep Earth volatiles

Science.gov (United States)

Parai, R.; Mukhopadhyay, S.

2017-12-01

The modern deep Earth volatile budget reflects primordial volatiles delivered during accretion, radiogenic ingrowth of volatile species (e.g., 40Ar produced by 40K decay), outgassing in association with mantle processing, and regassing via subduction. The noble gases are unique volatile tracers in that they are chemically inert, but are thought to be trapped within hydrous alteration phases in downwelling lithologies. Noble gases thus provide a tracer of volatile transport between the deep Earth and surface reservoirs. Constraints on the fluxes of noble gases between deep Earth and surface reservoirs over time can accordingly be used to provide insight into temperature conditions at subduction zones, limits on volatile cycling, and the evolving distribution of major volatile species in terrestrial reservoirs over time. Xe isotope systematics in mantle-derived rocks show that 80-90% of the mantle Xe budget is derived from recycling of atmospheric Xe, indicating that atmospheric Xe is retained in subducting slabs beyond depths of magma generation in subduction zones over Earth history. We present an integrated model of Xe cycling between the mantle and atmosphere in association with mantle processing over Earth history. We test a wide variety of outgassing and regassing rates and take the evolution of the atmospheric Xe isotopic composition [e.g., 1] into account. Models in which the deep Earth transitions from a net outgassing to net regassing regime best satisfy Xe isotopic constraints from mantle-derived rocks [2-6]. [1] Avice et al., 2017; Nature Communications, 8; [2] Mukhopadhyay, 2012, Nature 486, 101-104; [3] Parai et al., 2012, EPSL 359-360, 227-239; [4] Parai and Mukhopadhay, 2015, G-cubed 16, 719-735; [5] Peto et al., 2013, EPSL 369-370, 13-23; [6] Tucker et al., 2012, EPSL 355-356, 244-254.

Closing in on parton energy loss with charged particle spectra in Xe-Xe and Pb-Pb collisions with ALICE

CERN Multimedia

CERN. Geneva

2018-01-01

For comparison, a pp reference at the collision energy of 5.44 TeV is obtained by interpolating between existing pp measurements at 5.02 and 7 TeV.  The nuclear modification factor in Xe-Xe collisions is compared to Pb-Pb collisions at 5.02 TeV and 2.76 TeV, showing remarkable similarity at pT > 10 GeV/c. The comparison of the measured nuclear mod...

Modulation of ERG channels by XE991

DEFF Research Database (Denmark)

Elmedyb, Pernille; Calloe, Kirstine; Schmitt, Nicole

2007-01-01

In neuronal tissue, KCNQ2-5 channels conduct the physiologically important M-current. In some neurones, the M-current may in addition be conducted partly by ERG potassium channels, which have widely overlapping expression with the KCNQ channel subunits. XE991 and linopiridine are known to be stan......In neuronal tissue, KCNQ2-5 channels conduct the physiologically important M-current. In some neurones, the M-current may in addition be conducted partly by ERG potassium channels, which have widely overlapping expression with the KCNQ channel subunits. XE991 and linopiridine are known...... to be standard KCNQ potassium channel blockers. These compounds have been used in many different tissues as specific pharmacological tools to discern native currents conducted by KCNQ channels from other potassium currents. In this article, we demonstrate that ERG1-2 channels are also reversibly inhibited by XE......991 in the micromolar range (EC(50) 107 microM for ERG1). The effect has been characterized in Xenopus laevis oocytes expressing ERG1-2 and in the mammalian HEK293 cell line stably expressing ERG1 channels. The IC(50) values for block of KCNQ channels by XE991 range 1-65 microM. In conclusion, great...

Double-electron excitation above Xe K-edge

International Nuclear Information System (INIS)

Ito, Y.; Tochio, T.; Vlaicu, A.M.; Mutaguchi, K.; OhHashi, H.; Shigeoka, N.; Nakata, Y.; Akahama, Y.; Uruga, T.; Emura, Sh.

2000-01-01

When X-rays fall on any substance, whether solid, liquid, or gaseous, a photoabsorption occurs. Photoabsorption in atoms has been generally treated as a single-electron excitation process. However, the existence of the multi-electron excitation process, where the removal of a core electron by photoabsorption causes excitation of additional electrons in the same atoms, has been known in x-ray absorption spectra for a long time. In x-ray absorption spectra, experimental investigations of the shake processes in inner-shell ionization phenomena have been performed by detecting discontinuities. The shake effect which is a consequence of rearrangement of the atomic electrons, occurs in association with inner-shell excitation and ionization phenomena in x-ray absorption. The shake process has been studied extensively in various gases, because it is usually considered that the measurement of the multi-electron excitation is only possible for monatomic gases or vapors. The x-ray absorption spectra in Kr gas were measured by Ito et al. in order to observe precisely x-ray absorption spectra and to investigate the multi-electron excitation cross sections in Kr as a function of photon energy using synchrotron radiation. However, no suitable measured K x-ray absorption spectra was available to elucidate the shake processes. In the present work, the photoabsorption cross sections in Xe have been precisely measured in order to determine the features on the shake processes resulting from multiple electron excitations as a function of photon energy. Double-electron transitions of [1s4d], [1s4p], [1s4s], and [1s3d] are first detected. (author)

Constraints on the timing of the Moon-forming giant impact from MORB Xe isotopes

Science.gov (United States)

Parai, R.; Mukhopadhyay, S.

2014-12-01

As Earth accreted, volatiles were delivered by accreting material and lost by degassing and impact-driven ejection to space. The Moon-forming giant impact initiated the final catastrophic outgassing and bulk volatile ejection event on the early Earth. I-Pu-U-Xe systematics provide a powerful tool to probe degassing of the early Earth. Radiogenic 129Xe was produced by β-decay of the extinct nuclide 129I (t1/2 = 15.7 Ma) in the first ~90 Myr of Earth history. Fissiogenic 131Xe, 132Xe, 134Xe, 136Xe were produced in distinct, characteristic proportions by the fission of extinct short-lived 244Pu (t1/2 = 80.0 Myr) and extant long-lived 238U (t1/2 = 4.468 Gyr). Here we present radiogenic and fission Xe data in basalts from the Southwest Indian Ridge, and discuss them with other mantle-derived samples to shed light on early Earth volatile accretion and loss. Based on the ratio of radiogenic 129Xe to plutogenic 136Xe determined for the MORB source, we calculate an I-Pu-Xe closure age for the upper mantle of ~44-70 Myr after the start of the Solar System. The closure age should correspond to the end of catastrophic mantle outgassing during accretion, and thus constrains the age of the last giant impact (LGI). Our closure age is significantly older than previous Xe closure age determinations of ~100 Myr, and is also older than some direct radiometric ages of lunar crustal samples. In order to explore the effects of accretion timescales, partial early retention of Xe, and degassing associated with long-term mantle processing on Xe closure age, we develop a new model of I-Pu-U-Xe systematics. We find that for LGI's between ~35 and 70 Myr after the start of the Solar System, we are able to satisfy constraints on I-Pu-U-Xe systematics simultaneously without invoking partial retention of Xe prior to the last giant impact. For LGI's after ~80 Myr, partial retention of Xe prior to the LGI is required. Non-zero early retention of Xe is necessary to explain the budgets of primordial

Differential elastic scattering of He* (21S) by Ar, Kr and Xe: Repulsive rainbows and optical potentials

International Nuclear Information System (INIS)

Martin, D.W.; Gregor, R.W.; Jordan, R.M.; Siska, P.E.

1978-01-01

Elastic scattering angular distributions of He* (2 1 S) with Ar, Kr, and Xe measured in crossed atomic beams at collision energies from 0.4--2.8 kcal/mole are analyzed using a physically motivated optical potential model. The resulting potentials show some features expected on the basis of the analogous Li--rare gas potentials: monotonically increasing van der Waals well depths epsilon in the sequence Ar, Kr, Xe, and nearly constant well position r/sub m/. However, structure occurs in the repulsive parts of the potentials in the form of a local slope maximum (force minimum) at low positive potential energy, as suggested by other studies. The potential energy at the slope maximum decreases monotonically in the Ar, Kr, Xe sequence, while its position increases monotonically. The slope maximum is manifested in the angular distributions through the appearance of rainbow scattering peaks for Ar and Kr at angles well removed from those at which attractive rainbows are expected, with both repulsive and attractive rainbows evident in the same distribution. The resonance widths are constrained to be simple exponentials. Table I contains all potential parameters derived. Reasonably good agreement is obtained between measured total ionization cross sections and quenching rate constants and those calculated from the optical potentials

Characterization of Cr-rich Cr-Sb multilayer films: Syntheses of a new metastable phase using modulated elemental reactants

International Nuclear Information System (INIS)

Regus, Matthias; Mankovsky, Sergiy; Polesya, Svitlana; Kuhn, Gerhard; Ditto, Jeffrey; Schürmann, Ulrich; Jacquot, Alexandre; Bartholomé, Kilian; Näther, Christian; Winkler, Markus; König, Jan D.; Böttner, Harald; Kienle, Lorenz; Johnson, David C.; Ebert, Hubert; Bensch, Wolfgang

2015-01-01

The new metastable compound Cr 1+x Sb with x up to 0.6 has been prepared via a thin film approach using modulated elemental reactants and investigated by in-situ X-ray reflectivity, X-ray diffraction, differential scanning calorimetry, energy dispersive X-ray analysis as well as transmission electron microscopy and atomic force microscopy. The new Cr-rich antimonide crystallizes in a structure related to the Ni 2 In-type structure, where the crystallographic position (1/3, 2/3, 3/4) is partially occupied by excess Cr. The elemental layers of the pristine material interdiffused significantly before Cr 1+x Sb crystallized. A change in the activation energy was observed for the diffusion process when crystal growth starts. First-principles electronic structure calculations provide insight into the structural stability, magnetic properties and resistivity of Cr 1+x Sb. - Graphical abstract: 1 amorphous multilayered film 2 interdiffused amorphous film 3 metastable crystalline phase 4 thermodynamic stable phase (and by-product). - Highlights: • Interdiffusion of amorphous Cr and Sb occurs before crystallization. • Crystallization of a new metastable phase Cr 1.6 Sb in Ni 2 In-type structure. • The new Cr-rich phase shows half-metallic behavior

Relativistic coupled-cluster calculations of 20Ne, 40Ar, 84Kr, and 129Xe: Correlation energies and dipole polarizabilities

International Nuclear Information System (INIS)

Mani, B. K.; Angom, D.; Latha, K. V. P.

2009-01-01

We have carried out a detailed and systematic study of the correlation energies of inert gas atoms Ne, Ar, Kr, and Xe using relativistic many-body perturbation theory and relativistic coupled-cluster theory. In the relativistic coupled-cluster calculations, we implement perturbative triples and include these in the correlation energy calculations. We then calculate the dipole polarizability of the ground states using perturbed coupled-cluster theory.

Echo-planar MR imaging of dissolved hyperpolarized 129Xe. Potential for M angiography

International Nuclear Information System (INIS)

Maansson, S.

2002-01-01

Purpose: The feasibility of hyperpolarized 129 Xe for fast MR angiography (MRA) was evaluated using the echo-planar imaging (EPI) technique. Material and Methods: Hyperpolarized Xe gas was dissolved in ethanol; a carrier agent with high solubility for Xe (Ostwald solubility coefficient 2.5) and long relaxation times. The dissolved Xe was injected as a bolus into a flow phantom where the mean flow velocity was 15 cm/s. Ultrafast EPI images with 44 ms scan time were acquired of the flowing bolus and the signal-to-noise ratios (SNR) were measured. Results: The relaxation times of hyperpolarized Xe in ethanol were measured to T1=160±11 s and T2 ≅ 20 s. The resulting images of the flowing liquid were of reasonable quality and had an SNR of about 70. Conclusion: Based on the SNR of the obtained Xe EPI images; it was estimated that rapid in vivo MRA with 129 Xe may be feasible; provided that an efficient; biologically acceptable carrier for Xe can be found and polarization levels of more than 25% can be achieved in isotopically enriched 129 Xe

Coulomb states in atoms and solids

International Nuclear Information System (INIS)

Ortalano, D.M.

1988-05-01

In this dissertation, an empirical quantum defect approach to describe the valence excitons of the rare gas solids is developed. These Coulomb states are of s-symmetry and form a hydrogen-like series which converges to the bottom of the lowest conduction band. A non-zero quantum defect is found for all of the excitons of neon, argon and xenon. For these systems, then, there exists, in addition to the screened Coulombic component, a non-Coulombic component to the total exciton binding energy. The Wannier formalism is, therefore, inappropriate for the excitons of Ne, Ar and Xe. From the sign of the quantum defect, the non-Coulombic potential is repulsive for Ne and Ar, attractive for Xe, and nearly zero for Kr. This is opposite to that for the Rydberg states of the corresponding rare gas atoms, where the non-Coulombic potential between the electron and the cation is attractive for all of the atoms. The excitons then, are not simply perturbed Rydberg states of the corresponding rare gas atoms (i.e., the excitons do not possess atomic parentage). Interatomic term value/band gap energy correlations and reduced term value/reduced band gap correlations were performed. These correlations were exploited to provide further evidence against both the Wannier formalism and the atomic parentage view point. From these correlations, it was also discovered that the non-Coulombic potential varies smoothly across the valence isoelectronic series of solids, and that it becomes more attractive (or less repulsive) in going from neon to xenon. In order to address the atomic parentage controversy, it was necessary to compare the excitons to the low-n Rydberg states of the rare gas atoms. A review of the quantum defect description of the atomic Rydberg states is, therefore, presented. Also, Rydberg term value/ionization energy correlations are discussed and compared with the analogous exciton correlations. 7 refs., 10 figs., 5 tabs

Laser techniques for spectroscopy of core-excited atomic levels

Science.gov (United States)

Harris, S. E.; Young, J. F.; Falcone, R. W.; Rothenberg, J. E.; Willison, J. R.

1982-01-01

We discuss three techniques which allow the use of tunable lasers for high resolution and picosecond time scale spectroscopy of core-excited atomic levels. These are: anti-Stokes absorption spectroscopy, laser induced emission from metastable levels, and laser designation of selected core-excited levels.

Chemi-ionization in the metastable neon--metastable argon system

International Nuclear Information System (INIS)

Neynaber, R.N.; Tang, S.Y.

1980-01-01

Studies were made by a merging-beams technique of the associative ionization (AI) reaction (1) Ne/sup asterisk/+Ar/sup asterisk/→NeAr + +e and the Penning ionization (PI) reactions (2) Ne/sup asterisk/+Ar/sup asterisk/→Ne+Ar + +e and (3) Ne/sup asterisk/+Ar/sup asterisk/→Ne + +Ar+e. The relative kinetic energy of the reactants was varied from 0.01 to 10 eV. The Ne/sup asterisk/ and Ar/sup asterisk/ each represents a composite of the metastable 0 P/sub 2,0/ states. There is a complication in the present investigation which arises because AI and PI occur in collisions of Ne/sup asterisk/ with ground-state Ar. Since the reactant beams consist of metastable as well as ground-state species, the measurements are composites of chemi-ionization in both the Ne/sup asterisk/--Ar/sup asterisk/ and Ne/sup asterisk/--Ar systems. Information on AI and PI for the Ne/sup asterisk/--Ar/sup asterisk/ system is obtained by subtracting from these composite measurements known contributions of the Ne/sup asterisk/--Ar system. From such information it appears that the molecular states of the reactants are different for reactions (2) and

High Sensitivity Detection of Xe Isotopes Via Beta-Gamma Coincidence Counting

International Nuclear Information System (INIS)

Bowyer, Ted W.; McIntyre, Justin I.; Reeder, Paul L.

1999-01-01

Measurement of xenon fission product isotopes is a key element in the global network being established to monitor the Comprehensive Nuclear-Test-Ban Treaty. Pacific Northwest National Laboratory has developed an automated system for separating Xe from air which includes a beta-gamma counting system for 131mXe, 133mXe, 133Xe, and 135Xe. Betas and conversion electrons are detected in a plastic scintillation cell containing the Xe sample. The counting geometry is nearly 100% for beta and conversion electrons. The resolution in the pulse height spectrum from the plastic scintillator is sufficient to observe distinct peaks for specific conversion electrons. Gamma and X-rays are detected in a NaI(Tl) scintillation detector which surrounds the plastic scintillator sample cell. Two-dimensional pulse height spectra of gamma energy versus beta energy are obtained. Each of the four xenon isotopes has a distinctive signature in the two-dimensional energy array. The details of the counting system, examples of two-dimensional beta-gamma data, and operational experience with this counting system will be described

Revised analysis of singly ionized xenon, Xe II

International Nuclear Information System (INIS)

Hansen, J.E.; Persson, W.

1987-01-01

We present a revised analysis of the spectrum of singly ionized xenon, Xe II. This spectrum has been reanalyzed on the basis of the wavelength material published by Drs J. C. Boyce and C. J. Humphreys. The latter has kindly placed the original wavelength list covering the wavelength range 10220-390 A at our disposal. We report 161 energy levels which have been identified on the basis of classifications of 950 lines. We report first f and g levels in Xe II. Also a number of g-factors have been determined for the first time and we give in total 75 g-factors. We have carried out least-squares fits to the even configurations and report the resulting parameter values and eigenvector compositions. A least-squares fit to the 5p 4 6p configuration is also reported. The levels have been named in jK and for many levels also in LS coupling. The former is the better coupling scheme for Xe II. We present an analysis of the 5s photoelectron satellite spectrum of Xe based on our calculated eigenvector compositions and calculations of transition probabilities for ground state transitions as well as lifetimes for the 6p levels. The latter are compared to recent experimental measurements. A list of wavelengths for observed laser transitions showing the present classifications and a discussion of the determination of the ionization potential of Xe II concludes the paper. (orig.)

Bose-Einstein condensation of atomic gases

International Nuclear Information System (INIS)

Anglin, J. R.; Ketterle, W.

2003-01-01

The early experiments on Bose-Einstein condensation in dilute atomic gases accomplished three longstanding goals. First, cooling of neutral atoms into their motional state, thus subjecting them to ultimate control, limited only by Heisenberg uncertainty relation. Second, creation of a coherent sample of atoms, in which all occupy the same quantum states, and the realization of atom lasers - devices that output coherent matter waves. And third, creation of gaseous quantum fluid, with properties that are different from the quantum liquids helium-3 and helium-4. The field of Bose-Einstein condensation of atomic gases has continued to progress rapidly, driven by the combination of new experimental techniques and theoretical advances. The family of quantum degenerate gases has grown, and now includes metastable and fermionic atoms. condensates have become an ultralow-temperature laboratory for atom optics, collisional physics and many-body physics, encompassing phonons, superfluidity, quantized vortices, Josephson junctions and quantum phase transitions. (author)

Many-body effects on the structures and stability of Ba{sup 2+}Xe{sub n} (n = 1–39, 54) clusters

Energy Technology Data Exchange (ETDEWEB)

Abdessalem, Kawther, E-mail: kawtherabdessalem@yahoo.fr; Habli, Héla; Ghalla, Houcine [Laboratoire de Physique Quantique, Faculté des Sciences de Monastir, Université de Monastir, Avenue de l’Environnement, 5019 Monastir (Tunisia); Yaghmour, Saud Jamil [Physics Department, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Calvo, Florent [University of Grenoble Alpes, LIPHY, F-38000 Grenoble, France and CNRS, LIPHY, F-38000 Grenoble (France); Oujia, Brahim [Laboratoire de Physique Quantique, Faculté des Sciences de Monastir, Université de Monastir, Avenue de l’Environnement, 5019 Monastir (Tunisia); Physics Department, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia)

2014-10-21

The structures and relative stabilities of mixed Ba{sup 2+}Xe{sub n} (n = 1–39, 54) clusters have been theoretically studied using basin-hopping global optimization. Analytical potential energy surfaces were constructed from ab initio or experimental data, assuming either purely additive interactions or including many-body polarization effects and the mutual contribution of self-consistent induced dipoles. For both models the stable structures are characterized by the barium cation being coated by a shell of xenon atoms, as expected from simple energetic arguments. Icosahedral packing is dominantly found, the exceptional stability of the icosahedral motif at n = 12 being further manifested at the size n = 32 where the basic icosahedron is surrounded by a dodecahedral cage, and at n = 54 where the transition to multilayer Mackay icosahedra has occurred. Interactions between induced dipoles generally tend to decrease the Xe-Xe binding, leading to different solvation patterns at small sizes but also favoring polyicosahedral growth. Besides attenuating relative energetic stability, many-body effects affect the structures by expanding the clusters by a few percents and allowing them to deform more.

Entropy-driven metastable defects in silicon

International Nuclear Information System (INIS)

Hamilton, B.; Peaker, A.R.; Pantelides, S.T.

1989-01-01

The known metastable defects are usually describable by a configuration coordinate diagram in which two energy minima are separated by a barrier. This diagram does not change with temperature and each configuration is stable over some temperature range. Here we report the observation of a novel metastability: A configuration change occurs spontaneously and abruptly at a critical temperature, giving rise to a discontinuous DLTS (deep level transient spectroscopy) spectrum. We propose that this phenomenon is a manifestation of entropy variations in the configurational space. (author) 12 refs., 4 figs

Chalcogenides Metastability and Phase Change Phenomena

CERN Document Server

Kolobov, Alexander V

2012-01-01

A state-of-the-art description of metastability observed in chalcogenide alloys is presented with the accent on the underlying physics. A comparison is made between sulphur(selenium)-based chalcogenide glasses, where numerous photo-induced phenomena take place entirely within the amorphous phase, and tellurides where a reversible crystal-to-amorphous phase-change transformation is a major effect. Applications of metastability in devices¿optical memories and nonvolatile electronic phase-change random-access memories among others are discussed, including the latest trends. Background material essential for understanding current research in the field is also provided.

Discharge efficiency in high-Xe-content plasma display panels

NARCIS (Netherlands)

Hayashi, D.; Kroesen, G.M.W.; Hagelaar, G.J.M.; Heusler, G.

2004-01-01

We study theoretically the overall output performance and the dominating reaction processes of the vacuum ultraviolet (UV) radiation production in high-Xe partial pressures in plasma display panels (PDPs) with Ne-Xe gas mixtures. A two-dimensional self-consistent fluid model is applied for the

Modeling of Kr-Xe discharge of excimer lamp

Directory of Open Access Journals (Sweden)

Belasri A.

2013-03-01

Full Text Available This paper reports the numerical simulation of Dielectric Barrier Discharge (DBD for Kr-Xe excilamp. The model of the discharge consists of three main modules: a plasma chemistry module, a circuit module and a Boltzmann equation module. The results predict the optimal operating conditions and describe the electrical and chemical properties of the KrXe* excimer lamp.

Nuclear structure studies in highly neutron-deficient (114,116)Xe

Science.gov (United States)

Degraaf, James Hendrick

Lifetimes of nuclear states in 114Xe and 116Xe were measured for the first time; these nuclei represent the most neutron-deficient isotopes of xenon for which lifetimes have now been measured. The fusion-evaporation reactions 58Ni(60Ni, 2p)116Xe at 223 MeV beam energy and 58Ni(58Ni, 2p)114Xe at 215 MeV beam energy were used. Lifetimes were measured using the Recoil Distance Method (RDM) with the 8π gamma-ray spectrometer at Chalk River Laboratories. The new measurements of the B(E2;2+/to 0+) strength in these nuclei, coupled with the recent measurements for heavier xenon isotopes, are well described within the framework of the O(6) symmetry limit of the Interacting Boson Approximation. The octupole nature of the negative parity side-band was also studied, and the lifetime measurements indicate a change from a K/approx 3 structure in heavier xenon isotopes to a K/approx 0,/ 1 structure in 114Xe.

XeBr excilamp based on a non-toxic component mixture

Energy Technology Data Exchange (ETDEWEB)

Kelman, V A; Shpenik, Yu O; Zhmenyak, Yu V, E-mail: mironkle@rambler.ru [Institute of Electron Physics, National Academy of Sciences of Ukraine, Universitetska 21, 88017 Uzhgorod (Ukraine)

2011-06-29

This paper presents the results of experimental studies on obtaining UV luminescence of XeBr* molecules at the excitation of a non-toxic Xe-CsBr gas-vapour mixture by a longitudinal pulse-periodic discharge. Effective UV emission yield of the exciplex XeBr* molecules (spectral maximum at 282 nm) is observed within a wide range of excitation conditions. The spectral distribution in the UV emission under the optimal excitation conditions does not differ essentially from that in other XeBr excilamps based on toxic components. The emission of the B {yields} X band of the XeBr* molecules provides the main contribution to the total power of the discharge UV emission. The determined average power of the UV emission for the experimental discharge tube is 12 W at an efficiency of 1%. Spectral, power-related and time-dependent parameters of the laboratory excilamp are presented for a wide range of excitation parameters. A new mechanism of exciplex molecule formation at the excitation of a rare gas/alkali halide vapour mixture is discussed.

XeBr excilamp based on a non-toxic component mixture

International Nuclear Information System (INIS)

Kelman, V A; Shpenik, Yu O; Zhmenyak, Yu V

2011-01-01

This paper presents the results of experimental studies on obtaining UV luminescence of XeBr* molecules at the excitation of a non-toxic Xe-CsBr gas-vapour mixture by a longitudinal pulse-periodic discharge. Effective UV emission yield of the exciplex XeBr* molecules (spectral maximum at 282 nm) is observed within a wide range of excitation conditions. The spectral distribution in the UV emission under the optimal excitation conditions does not differ essentially from that in other XeBr excilamps based on toxic components. The emission of the B → X band of the XeBr* molecules provides the main contribution to the total power of the discharge UV emission. The determined average power of the UV emission for the experimental discharge tube is 12 W at an efficiency of 1%. Spectral, power-related and time-dependent parameters of the laboratory excilamp are presented for a wide range of excitation parameters. A new mechanism of exciplex molecule formation at the excitation of a rare gas/alkali halide vapour mixture is discussed.

A metastable liquid melted from a crystalline solid under decompression

Science.gov (United States)

Lin, Chuanlong; Smith, Jesse S.; Sinogeikin, Stanislav V.; Kono, Yoshio; Park, Changyong; Kenney-Benson, Curtis; Shen, Guoyin

2017-01-01

A metastable liquid may exist under supercooling, sustaining the liquid below the melting point such as supercooled water and silicon. It may also exist as a transient state in solid-solid transitions, as demonstrated in recent studies of colloidal particles and glass-forming metallic systems. One important question is whether a crystalline solid may directly melt into a sustainable metastable liquid. By thermal heating, a crystalline solid will always melt into a liquid above the melting point. Here we report that a high-pressure crystalline phase of bismuth can melt into a metastable liquid below the melting line through a decompression process. The decompression-induced metastable liquid can be maintained for hours in static conditions, and transform to crystalline phases when external perturbations, such as heating and cooling, are applied. It occurs in the pressure-temperature region similar to where the supercooled liquid Bi is observed. Akin to supercooled liquid, the pressure-induced metastable liquid may be more ubiquitous than we thought.

The interaction between Xe and F in Si (1 0 0) pre-amorphised with 20 keV Xe and implanted with low energy BF{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Werner, M. [Joule Physics Laboratory, Institute of Materials Research, University of Salford, Salford M54WT (United Kingdom)]. E-mail: m.werner@pgr.salford.ac.uk; Berg, J.A. van den [Joule Physics Laboratory, Institute of Materials Research, University of Salford, Salford M54WT (United Kingdom); Armour, D.G. [Joule Physics Laboratory, Institute of Materials Research, University of Salford, Salford M54WT (United Kingdom); Carter, G. [Joule Physics Laboratory, Institute of Materials Research, University of Salford, Salford M54WT (United Kingdom); Feudel, T. [AMD Saxony LLC and Co. KG, Wilschdorfer Landstrasse, 101 D-01109 Dresden (Italy); Herden, M. [AMD Saxony LLC and Co. KG, Wilschdorfer Landstrasse, 101 D-01109 Dresden (Italy); Bersani, M. [ITC IRST, 38050 Povo, Trento (Italy); Giubertoni, D. [ITC IRST, 38050 Povo, Trento (Italy); Bailey, P. [CCLRC Daresbury Laboratory, Daresbury WA44A (United Kingdom); Noakes, T.C.Q. [CCLRC Daresbury Laboratory, Daresbury WA44A (United Kingdom)

2004-12-15

The pre-amorphisation of Si by Xe{sup +} ions, before source/drain and extension implants, is an attractive alternative to Ge{sup +} or Si{sup +}, as it produces sharper amorphous/crystalline interfaces. Si (1 0 0) samples pre-amorphised with 20 keV Xe{sup +} to a nominal dose of 2E14 cm{sup -2} were implanted with 1 and 3 keV BF{sub 2} {sup +} to doses of 7E14 cm{sup -2}. Samples were annealed at temperatures ranging from 600 to 1130 deg. C and investigated by medium energy ion scattering (MEIS) and secondary ion mass spectrometry (SIMS). Following annealing, it was observed that implanted Xe has interacted with F originating from the BF{sub 2} {sup +} implant. MEIS studies showed that for all annealing conditions, approximately half of the Xe accumulated at depths of 7 nm for the 1 keV and at 13 nm for the 3 keV BF{sub 2} {sup +} implant. This equates to the end of range of B and F within the amorphous Si. SIMS showed that in the pre-amorphised samples, approximately 10% of the F migrates into the bulk and is trapped at the same depth in a {approx}1:1 ratio to Xe. A small fraction of the implanted B is also trapped. The effect is interpreted in terms of the formation of a defect structure within the amorphised Si, leading to F stabilised Xe bubble or XeF compound formation.

Fourier photospectroscopy of Xe-C60 through a Xe 4d resonance window: theory versus recent experiment

International Nuclear Information System (INIS)

Patel, Aakash B; Chakraborty, Himadri S

2011-01-01

The photoionization cross section of endohedral Xe-C 60 over a Xe 4d giant resonance energy region, calculated in the time-dependent local density approximation, is compared with recent measurements (Kilcoyne et al 2010 Phys. Rev. Lett. 105 213001). An analysis based on the Fourier transforms of oscillatory cross sections is performed to derive a number of inherent similarities between the prediction and the data, including a large beating-type oscillation and several others of intermediate size. Results stress the need for more accurate measurements to access the wealth of information about the geometry of the system. (fast track communication)

Metastable defect response in CZTSSe from admittance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Koeper, Mark J.; Hages, Charles J.; Li, Jian V.; Levi, Dean; Agrawal, Rakesh

2017-10-02

Admittance spectroscopy is a useful tool used to study defects in semiconductor materials. However, metastable defect responses in non-ideal semiconductors can greatly impact the measurement and therefore the interpretation of results. Here, admittance spectroscopy was performed on Cu2ZnSn(S,Se)4 where metastable defect response is illustrated due to the trapping of injected carriers into a deep defect state. To investigate the metastable response, admittance measurements were performed under electrically and optically relaxed conditions in comparison to a device following a low level carrier-injection pretreatment. The relaxed measurement demonstrates a single capacitance signature while two capacitance signatures are observed for the device measured following carrier-injection. The deeper level signature, typically reported for kesterites, is activated by charge trapping following carrier injection. Both signatures are attributed to bulk level defects. The significant metastable response observed on kesterites due to charge trapping obscures accurate interpretation of defect levels from admittance spectroscopy and indicates that great care must be taken when performing and interpreting this measurement on non-ideal devices.

Metastability and Rydberg states of triatomic hydrogen

International Nuclear Information System (INIS)

Helm, H.

1991-01-01

The np,nd and nf Rydberg series of H 3 have been studied by one- or two-photon excitation from the lowest metastable state of H 3 :B2p 2 A 2 ''. The lifetime of the metastable state has been measured and the influence of an external electric field on the Rydberg states has been studied under both aspects of dynamics (field-ionization and field-induced predissociation) and structure (Strak effect)

A sensitive zinc-activated 129Xe MRI probe

International Nuclear Information System (INIS)

Kotera, N.; Delacour, L.; Traore, T.; Buisson, D.A.; Taran, F.; Coudert, S.; Rousseau, B.; Tassali, N.; Leonce, E.; Boutin, C.; Berthault, P.; Brotin, T.; Dutasta, J.P.

2012-01-01

Herein we propose the use of hyper-polarized 129 Xe nuclear magnetic resonance (NMR) spectroscopy for the sensitive detection of Zn 2+ ions. To achieve this goal, the noble gas is encapsulated in dedicated host systems bearing a ligand that chelates the Zn 2+ ions. Cryptophanes, aromatic cage molecules made of cyclotriveratrylene groups, are perfectly suited to this purpose as 1) they can easily be rendered water-soluble, 2) the noble gas has a high affinity for their cavity, 3) when xenon is encapsulated, it takes a specific NMR frequency, and 4) xenon exchange in and out of the cavity insures a continuous refreshment of the Xe-cryptophane environment in hyper-polarization. We constructed a powerful 129 Xe NMR-based sensor of Zn 2+ ions, which enables for the first time measurement of Zn 2+ concentrations as low as 100 nm. This high sensitivity was achieved thanks to a smart 129 Xe MRI sensor, where the binding of the ion to the target is accompanied by a change in NMR parameters. We have also demonstrated the importance of working with enantiopure cryptophane derivatives. (O.M.)

Neutron Inelastic Scattering on 134Xe at En = 5 - 8 MeV

Science.gov (United States)

Kidd, Mary; Tornow, Werner; Finch, Sean; Krishichayan, Fnu; Bhike, Megha

2017-09-01

Neutrinoless double-beta decay (0 νββ) studies are both the best way to determine the Majorana nature of the neutrino and determine its effective mass. The two main experiments searching for 0 νββ -decay of 136Xe (Q value = 2457.8 keV) are Kamland-Zen and EXO-200. Though both experiments have enriched 136Xe targets, these targets still contain significant quantities of 134Xe. Recently, a new nuclear level was discovered in 134Xe that decays to the ground state emitting a 2485.7 keV gamma ray. The γ-ray production cross section for this branch was found to be on the order of 10 mb for incident neutron energies of 2.5-4.5 MeV. Here, we have extended the investigation of this level to higher incident neutron energies, and further explore the potential neutron-induced backgrounds on both 134Xe and 136Xe for extended neutron energies. We will report our preliminary results for neutron inelastic scattering on 134Xe in applications to 0 νββ decay searches. NSF PHY-1614348, DE-FG02-97ER41033.

Measurements of Positronium Formation Cross Sections for Positron-Kr, Xe Scattering

Science.gov (United States)

Kauppila, W. E.; Kwan, C. K.; Li, H.; Stein, T. S.; Zhou, S.

1997-04-01

Our experimental approach(S. Zhou et al., Phys. Rev. Lett. 73, 236 (1994).) for measuring Ps formation cross sections (Q_Ps) involves passing a variable energy positron beam through a gas scattering cell and detecting the 511 keV annihilation gamma rays resulting from the decay of para-Ps and from the interaction of ortho-Ps with the walls of the scattering cell. It is found that the Q_Ps curves for both Kr and Xe rise rapidly from their formation threshold energies of 7.2 and 5.3 eV, reach maxima within about 10 eV of their thresholds and then decrease to become rather small (less than 10% of the peak heights) above 100 eV. At the maxima Q_Ps accounts for more than 50% of the total scattering cross sections. There is some evidence of possible small scale structure in the Q_Ps curves between 10 and 100 eV. The present results are consistent with the prior measurements of Diana et al.( L.M. Diana et al., in "Atomic Physics with Positrons", edited by J.W. Humberston and E.A.G. Armour (Plenum, New York and London, 1987), p. 55; and in "Positron Annihilation", edited by L. Dorikens-Vanpraet et al. (World Scientific, Singapore, 1989), p. 311.) from near threshold to 70 eV for Kr and from 15 to 100 eV for Xe.

Population distribution of atomic uranium in the afterglow of a pulsed hollow-cathode discharge

International Nuclear Information System (INIS)

Demers, Yves; Gagne, J.-M.; Pianarosa, Piero

1987-01-01

From laser absorption measurements we have deduced the time evolution of the population distribution of atomic uranium in the afterglow of a pulsed hollow-cathode type discharge. The vapour generator operates with xenon as the discharge sustaining gas at a pressure of 280 Pa (2.1 Torr). The current pulse characteristics are width 250 μs and height 1.5 A. The pulse repetition frequency is 100 Hz. It is shown that the populations in the three metastable levels at 6249, 3868 and 3800 cm -1 decrease almost exponentially in a time interval between 150 and 300 μs. From 400 μs onwards in the afterglow, the atom population is essentially shared between the ground and the first metastable (620 cm -1 ) levels. Furthermore, starting from 9 ms in the afterglow more than 80% of the U atoms are found in the ground level. (author)

Regional lung function (133Xe-radiospirometry) in bronchial cancer

International Nuclear Information System (INIS)

Arborelius, M.; Kristersson, S.; Lindell, S.E.

1976-01-01

In a prospective study of all patients with bronchial cancer in the city of Malmoe, all patients considered for surgery were examined with regard to overall function (conventional spirometry) and regional lung function (133-Xe-radiospirometry). Out of 116 consecutive cases examined with 133-Xe-radiospirometry before surgery,

Kr and Xe isotopes from spontaneous fission of 248Cm and 250Cf

International Nuclear Information System (INIS)

Srinivasan, B.

1980-01-01

Relative yields of Kr and Xe isotopes from the spontaneous fission of 248 Cm and 250 Cf have been determined mass spectrometrically. The yields are as follows: 83 Kr/ 84 Kr/ 85 Kr/ 86 Kr = 0.223/0.458/0.596/ identical 1.00 and 0.306/0.582/0.793/ identical 1.00; 131 Xe/ 134 Xe/ 136 Xe = 0.486/0.819/1.075 identical 1.00 and 0.343/0.506/0.851/ identical 1.00 from 248 Cm and 250 Cf, respectively. The Xe yields from 248 Cm agree with an earlier determination by Leich et al. Neither of these yield patterns matches that of fissiogenic Kr and Xe in carbonaceous chondrites and hence 248 Cm and 250 Cf are ruled out as progenitors of the meteoritic Kr and Xe. In general, none of the spontaneously fissioning nuclides of actinide elements can be identified as a possible progenitor. Even the mixtures of actinides, including a combination of 248 Cm and 250 Cm, are unsuitable. The origin of anomalous Kr and Xe in carbonaceous chondrites must then be traced either to the spontaneous fission of a superheavy element or to peculiarities in specific nucleosynthetic reactions. (orig.)

Atomic quasi-Bragg-diffraction in a magnetic field

NARCIS (Netherlands)

Domen, K.F.E.M.; Jansen, M.A.H.M.; Dijk, van W.; Leeuwen, van K.A.H.

2009-01-01

We report on a technique to split an at. beam coherently with an easily adjustable splitting angle. In our expt. metastable helium atoms in the |{1s2s}3S1 M=1 state diffract from a polarization gradient light field formed by counterpropagating .sigma.+ and .sigma.- polarized laser beams in the

Mass spectrometry of solid samples in open air using combined laser ionization and ambient metastable ionization

International Nuclear Information System (INIS)

He, X.N.; Xie, Z.Q.; Gao, Y.; Hu, W.; Guo, L.B.; Jiang, L.; Lu, Y.F.

2012-01-01

Mass spectrometry of solid samples in open air was carried out using combined laser ionization and metastable ionization time-of-flight mass spectrometry (LI-MI-TOFMS) in ambient environment for qualitative and semiquantitative (relative analyte information, not absolute information) analysis. Ambient metastable ionization using a direct analysis in realtime (DART) ion source was combined with laser ionization time-of-flight mass spectrometry (LI-TOFMS) to study the effects of combining metastable and laser ionization. A series of metallic samples from the National Institute of Standards and Technology (NIST 494, 495, 498, 499, and 500) and a pure carbon target were characterized using LI-TOFMS in open air. LI-MI-TOFMS was found to be superior to laser-induced breakdown spectroscopy (LIBS). Laser pulse energies between 10 and 200 mJ at the second harmonic (532 nm) of an Nd:YAG laser were applied in the experiment to obtain a high degree of ionization in plasmas. Higher laser pulse energy improves signal intensities of trace elements (such as Fe, Cr, Mn, Ni, Ca, Al, and Ag). Data were analyzed by numerically calculating relative sensitivity coefficients (RSCs) and limit of detections (LODs) from mass spectrometry (MS) and LIBS spectra. Different parameters, such as boiling point, ionization potential, RSC, LOD, and atomic weight, were shown to analyze the ionization and MS detection processes in open air.

Level structures of neutron-rich Xe isotopes

Energy Technology Data Exchange (ETDEWEB)

Ahmad, I.; Lister, C.J.; Morss, L.R. [and others

1995-08-01

The level structures of neutron-rich Xe isotopes were determined by observing prompt gamma-ray coincidences in {sup 248}Cm fission fragments. A 5-mg {sup 248}Cm, in the form of {sup 248}Cm-KCl pellet, was placed inside Eurogam array which consisted of 45 Compton-suppressed Ge detectors and 5 Low-Energy Photon Spectrometers. Transitions in Xe isotopes were identified by the appearance of new peaks in the {gamma}-ray spectra obtained by gating on the gamma peaks of the complementary Mo fragments.

Generation of atomic iodine via fluorine for chemical oxygen-iodine laser

Czech Academy of Sciences Publication Activity Database

Jirásek, Vít; Špalek, Otomar; Čenský, Miroslav; Picková, Irena; Kodymová, Jarmila; Jakubec, Ivo

2007-01-01

Roč. 334, - (2007), s. 167-174 ISSN 0301-0104 R&D Projects: GA ČR GA202/05/0359 Grant - others:USAF European Office for Research and Development(XE) FA 8655-05-M-4027 Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z40320502 Keywords : atomic iodine * atomic fluorine * chemical oxygen-iodine laser Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.805, year: 2007

On the bosonic atoms

Science.gov (United States)

Amusia, M. Ya.; Chernysheva, L. V.

2018-01-01

We investigate ground state properties of atoms, in which substitute fermions - electrons by bosons, namely π --mesons. We perform some calculations in the frame of modified Hartree-Fock (HF) equation. The modification takes into account symmetry, instead of anti-symmetry of the pair identical bosons wave function. The modified HF approach thus enhances (doubles) the effect of self-action for the boson case. Therefore, we accordingly modify the HF equations by eliminating the self-action terms "by hand". The contribution of meson-meson and meson-nucleon non-Coulomb interaction is inessential at least for atoms with low and intermediate nuclear charge, which is our main subject. We found that the binding energy of pion negative ions A π - , pion atoms A π , and the number of extra bound pions ΔN π increases with the growth of nuclear charge Z. For e.g. Xe ΔN π = 4. As an example of a simple process with a pion atom, we consider photoionization that differs essentially from that for electron atoms. Namely, it is not monotonic decreasing from the threshold but has instead a prominent maximum above threshold. We study also elastic scattering of pions by pion atoms.

The liquid metastable miscibility gap in Cu-based systems

DEFF Research Database (Denmark)

Curiotto, S.; Greco, R.; Pryds, Nini

2007-01-01

Some Cu-based alloys, like Cu–Co, Cu–Fe and Cu–Co–Fe, display a liquid metastable miscibility gap. When the melt is undercooled below a certain temperature depending on the alloy composition, they present a separation in two liquid phases, followed by coagulation before dendritic solidification....... In order to predict the phase equilibria and the mechanisms of microstructure formation, a determination of the metastable monotectics in the phase diagrams is essential. This paper focuses on the up-to-date findings on the Cu–Co, Cu–Fe and Cu–Co–Fe metastable miscibility gap in the liquid phase...

A few proofs for nonexistence of the metastable states

International Nuclear Information System (INIS)

Blazjevski, Atanas

2007-01-01

This paper is the bigger part of one until now unpublished author's work, whose title is 'A few proofs for nonexistence of the metastable states'. Because of a big volume of the work, the problems of supersaturated (metastable) steam which appears at the following of slightly, superheated, saturated or wet steam in the convergent and Laval nozzles will be discussed in the main. This steam is mentioned in the literature as one between of the strongest proofs for existence of metastable states in the substances. In this work the steam is not one -phase gaseous metastable steam, as it was thought until now, but yat it is nonequilibrium wet steam in which during the expanding process in the nozzles extreme small particles condensate, consisted of two, three or only few agglomerated molecules are formed which stay in heat, mechanical and internal nonequilibrium with the rest of the expanding gaseous phase of the steam. It means, that this steam, which is called a supersaturated or metastable steam, in fact does not exist in reality because it is nothing else but only nonequilibrium wet steam consisted of tho phases: the expanding gaseous phase of the steam in the nozzle and the mentioned small and nonequilibrium particles condensate which are formed there...

128Xe Lifetime Measurement Using the Coulex-Plunger Technique in Inverse Kinematics

International Nuclear Information System (INIS)

Konstantinopoulos, T.; Lagoyannis, A.; Harissopulos, S.; Dewald, A.; Rother, W.; Ilie, G.; Jones, P.; Rakhila, P.; Greenlees, P.; Grahn, T.; Julin, R.; Balabanski, D. L.

2008-01-01

The lifetimes of the lowest collective yrast and non-yrast states in 128 Xe were measured in a Coulomb excitation experiment using the recoil distance method (RDM) in inverse kinematics. Hereby, the Cologne plunger apparatus was employed together with the JUROGAM spectrometer. Excited states in 128 Xe were populated using a 128 Xe beam impinging on a nat Fe target with E( 128 Xe)≅525 MeV. Recoils were detected by means of an array of solar cells placed at forward angles. Recoil-gated γ-spectra were measured at different plunger distances

128Xe Lifetime Measurement Using the Coulex-Plunger Technique in Inverse Kinematics

Science.gov (United States)

Konstantinopoulos, T.; Lagoyannis, A.; Harissopulos, S.; Dewald, A.; Rother, W.; Ilie, G.; Jones, P.; Rakhila, P.; Greenlees, P.; Grahn, T.; Julin, R.; Balabanski, D. L.

2008-05-01

The lifetimes of the lowest collective yrast and non-yrast states in 128Xe were measured in a Coulomb excitation experiment using the recoil distance method (RDM) in inverse kinematics. Hereby, the Cologne plunger apparatus was employed together with the JUROGAM spectrometer. Excited states in 128Xe were populated using a 128Xe beam impinging on a natFe target with E(128Xe)~525 MeV. Recoils were detected by means of an array of solar cells placed at forward angles. Recoil-gated γ-spectra were measured at different plunger distances.

Calculation of Photonic decay width for meta-stable muonic symmetric ion in adiabatic representation method

International Nuclear Information System (INIS)

Gheisari, R.; Eskandari, M. R.

2006-01-01

Meta-stable symmetric ions ppμ * and ddμ * are formed in the collisions of the excited muonic atoms with the hydrogen isotopes. By dissociation of them, the muon transfers from 2s to 1s via the new channels. Considering the quantum electrodynamics field and employing the new wave functions, the matrix elements are simply integrated. In this method using the adiabatic representations, the photo-decay widths for the some of ppμ * and ddμ * states are variationally calculated. The decay rates for X-ray productions of the similar states are approximately same.

Decay of 132Cs and nuclear structure of 132Xe

International Nuclear Information System (INIS)

Cruz, M.T.F. da; Goldman, I.D.

1989-02-01

Gamma spectroscopy, coincidence and angular correlation experiments were performed, in an extensive study of 132 Cs decay. The population intensities of states in 132 Ba were measured, some upper limits were determined and the value of the transition to the 4 1 + state of 132 Ba has drastically changed. A new gamma transition of 688 KeV was detected and located in the level scheme of 132 Xe. The angular correlation measurements were performed with a Ge(Li)-NaI(Tl) spectrometer and helped in choosing the spin value for the 1804 KeV state of 132 Xe. Kumar-Baranger-type calculations were performed for the 132 Xe fairly good results. The resulting potential energy surface for 132 Xe is very different from that of Gneuss and Greiner model, suggesting the need for any quadrupole moment measurement for this nucleus. (author) [pt

Structural Properties and Thermodynamic Stability of Metastable Phases in the Zr-Nb and Ti-V Systems

International Nuclear Information System (INIS)

Aurelio, Gabriela

2003-01-01

The structural properties and relative stability of metastable phases have been studied in the Zr-Nb and Ti-V systems.The first part of this Thesis is connected to a previous work performed in our Group (G. Grad, PhD Thesis, Instituto Balseiro, Argentina, 1999).It presents a phenomenological analysis of the systematics of interatomic distances in the omega (Ω ) and bcc (β) phases of the transition metals, which concerns a parameter entering into Pauling's resonating-valence- bond-theory and the structural and bonding properties of the Ω and β phases.Neutron diffraction experiments in Zr-Nb and Ti-V alloys are reported, aimed at studying possible atomic ordering in the Ω phase and the composition dependence of its interatomic distances.An extensive neutron diffraction study was performed on a series of Zr-Nb and Ti-V alloys quenched from high temperatures, where β is the stable phase.Upon quenching, three metastable structures are formed, viz., the hcp (∝ q ) phase, the Ω q phase, and the untransformed β q phase.The structural properties of these metastable phases were determined as a function of the Nb and V contents to generate a reliable experimental database.With such data, a series of issues are discussed related to the structure, relative stability, and phase relations in the alloys and its constitutive elements.The effect of composition upon the lattice parameters of the metastable β q and Ω q phases was combined in a consistent way with a critical analysis of structural and thermophysical data on the metastable phases of Ti and Zr.The relative stability of the metastable ∝ q , Ω q and β q phases in Zr-Nb alloys, and its evolution towards thermodynamic equilibrium, were studied combining neutron thermodiffraction and analytical electron microscopy techniques.During isothermal heat treatments performed at high temperature, the structural properties of the alloys were determined as a function of temperature, time and composition.A method of

Theoretical simulations of atomic and polyatomic bombardment of an organic overlayer on a metallic substrate

CERN Document Server

Krantzman, K D; Delcorte, A; Garrison, B J

2003-01-01

Our previous molecular dynamics simulations on initial test systems have laid the foundation for understanding some of the effects of polyatomic bombardment. In this paper, we describe simulations of the bombardment of a more realistic model system, an overlayer of sec-butyl-terminated polystyrene tetramers on a Ag left brace 1 1 1 right brace substrate. We have used this model system to study the bombardment with Xe and SF sub 5 projectiles at kinetic energies ranging from 0.50 to 5.0 keV. SF sub 5 sputters more molecules than Xe, but a higher percentage of these are damaged rather than ejected intact when the bombarding energy is greater than 0.50 keV. Therefore, at energies comparable to experimental values, the efficiency, measured as the yield-to-damage ratio, is greater with Xe than SF sub 5. Stable and intact molecules are generally produced by upward moving substrate atoms, while fragments are produced by the upward and lateral motion of reflected projectile atoms and fragments from the target molecul...

Adsorption on metal oxides Studies with the metastable impact electron spectroscopy

CERN Document Server

Krischok, S; Kempter, V

2002-01-01

An overview is given on the application of metastable impact electron spectroscopy, in combination with UPS, to the study of clean magnesia and titania surfaces and their interaction with metal atoms and small molecules. The mechanisms for metal adsorption on reducible (titania) and non-reducible (magnesia) substrates are different: while on titania the metal atom often bonds by electron transfer to Ti3d states, it is hybridization of the adsorbate and anion wavefunctions which accounts for the bonding on MgO. In the case of H sub 2 O, molecular adsorption takes place both on MgO and TiO sub 2; on the other hand, water-alkali coadsorption leads to hydroxide formation. In the case of CO sub 2 , chemisorption takes place in form of carbonate (CO sub 3) species. These originate from the CO sub 2 interaction with O sup 2 sup - surface anions. While for CaO chemisorption takes place at regular oxygen sites, for MgO this occurs at low-coordinated oxygen ions only; for TiO sub 2 chemisorption requires alkali coadsor...

Adsorption on metal oxides: Studies with the metastable impact electron spectroscopy

International Nuclear Information System (INIS)

Krischok, S.; Hoefft, O.; Kempter, V.

2002-01-01

An overview is given on the application of metastable impact electron spectroscopy, in combination with UPS, to the study of clean magnesia and titania surfaces and their interaction with metal atoms and small molecules. The mechanisms for metal adsorption on reducible (titania) and non-reducible (magnesia) substrates are different: while on titania the metal atom often bonds by electron transfer to Ti3d states, it is hybridization of the adsorbate and anion wavefunctions which accounts for the bonding on MgO. In the case of H 2 O, molecular adsorption takes place both on MgO and TiO 2 ; on the other hand, water-alkali coadsorption leads to hydroxide formation. In the case of CO 2 , chemisorption takes place in form of carbonate (CO 3 ) species. These originate from the CO 2 interaction with O 2- surface anions. While for CaO chemisorption takes place at regular oxygen sites, for MgO this occurs at low-coordinated oxygen ions only; for TiO 2 chemisorption requires alkali coadsorption

A study of capillary discharge lamps in Ar-Hg and Xe-Hg mixtures

International Nuclear Information System (INIS)

Denisova, N; Gavare, Z; Revalde, G; Skudra, Ja; Veilande, R

2011-01-01

Low-pressure capillary discharge lamps in Ar-Hg and Xe-Hg mixtures are studied. The discharge size is 0.5 mm (500 μm) in radius. According to the literature, such types of plasma sources are classified as microplasmas. The studies include spectrally resolved optical measurements, tomographic reconstructions and numerical simulations using the collisional-radiative model for an Ar-Hg plasma. We discuss the problems of theoretical modelling and experimental diagnostics of microplasma sources. It is shown that the conventional collisional-radiative model, based on the assumption that transportation of atoms in the highly excited states can be neglected, has limitations in modelling a capillary discharge in an Ar-Hg mixture. It is found that diffusion of highly excited mercury atoms to the wall influences the emission properties of the capillary discharge. We have concluded that applications of the emission tomography method to microplasmas require a special analysis in each particular case.

Imaging Human Brain Perfusion with Inhaled Hyperpolarized 129Xe MR Imaging.

Science.gov (United States)

Rao, Madhwesha R; Stewart, Neil J; Griffiths, Paul D; Norquay, Graham; Wild, Jim M

2018-02-01

Purpose To evaluate the feasibility of directly imaging perfusion of human brain tissue by using magnetic resonance (MR) imaging with inhaled hyperpolarized xenon 129 ( 129 Xe). Materials and Methods In vivo imaging with 129 Xe was performed in three healthy participants. The combination of a high-yield spin-exchange optical pumping 129 Xe polarizer, custom-built radiofrequency coils, and an optimized gradient-echo MR imaging protocol was used to achieve signal sensitivity sufficient to directly image hyperpolarized 129 Xe dissolved in the human brain. Conventional T1-weighted proton (hydrogen 1 [ 1 H]) images and perfusion images by using arterial spin labeling were obtained for comparison. Results Images of 129 Xe uptake were obtained with a signal-to-noise ratio of 31 ± 9 and demonstrated structural similarities to the gray matter distribution on conventional T1-weighted 1 H images and to perfusion images from arterial spin labeling. Conclusion Hyperpolarized 129 Xe MR imaging is an injection-free means of imaging the perfusion of cerebral tissue. The proposed method images the uptake of inhaled xenon gas to the extravascular brain tissue compartment across the intact blood-brain barrier. This level of sensitivity is not readily available with contemporary MR imaging methods. © RSNA, 2017.

Fourier photospectroscopy of Xe-C{sub 60} through a Xe 4d resonance window: theory versus recent experiment

Energy Technology Data Exchange (ETDEWEB)

Patel, Aakash B; Chakraborty, Himadri S, E-mail: himadri@nwmissouri.edu [Center for Innovation and Entrepreneurship, Department of Chemistry and Physics, Northwest Missouri State University, Maryville, Missouri 64468 (United States)

2011-10-14

The photoionization cross section of endohedral Xe-C{sub 60} over a Xe 4d giant resonance energy region, calculated in the time-dependent local density approximation, is compared with recent measurements (Kilcoyne et al 2010 Phys. Rev. Lett. 105 213001). An analysis based on the Fourier transforms of oscillatory cross sections is performed to derive a number of inherent similarities between the prediction and the data, including a large beating-type oscillation and several others of intermediate size. Results stress the need for more accurate measurements to access the wealth of information about the geometry of the system. (fast track communication)

Relativistic many-body theory of atomic structures

International Nuclear Information System (INIS)

Cheng, K.T.

1983-01-01

The main objective of this program is to improve our understanding of the effect of relativity and electron correlations on atomic processes. Current efforts include hyperfine structure (hfs) studies using the multiconfiguration Dirac-Fock (MCDF) technique. Atomic hfs are known to be sensitive to relativity and electron correlations, and provide important tests of relativistic atomic many-body theories. Preliminary results on the hfs of the 4f 12 3 H ground state of 68 Er 167 are shown and are in good agreement with experiment. This shows that the MCDF technique can be an efficient and powerful method for atomic hfs studies. Further tests of this method are in progress. We are also studying the absorption spectra for Xe-like ions in the region of 4d → nf, epsilonf transitions

129Xe on the outgassing of the atmosphere

International Nuclear Information System (INIS)

Thomsen, L.

1980-01-01

Because of the short half-life of its parent ( 129 I, 17 m.y.) and its own chemical inertness, 129 Xe offers unique insight into the problem of the outgassing history of the earth's atmosphere. Because the current atmosphere is different in Xe isotopic patterns than is the interior, the present atmosphere must have been largely outgassed before these patterns finished changing, that is, very early in earth history. Furthermore, there can have been no significant delay in the onset of outgassing; that is, the earth must have been initially hot. Because ancient sedimentary rocks indicate that the atmospheric Xe patterns have not changed substantially for over 3 b.y., models presuming a separate, lower mantle reservoir do not alter these conclusions. Similar conclusions have been reached before but have always carried a heavier burden of debatable assumptions

Optical properties of implanted Xe color centers in diamond

Science.gov (United States)

Sandstrom, Russell; Ke, Li; Martin, Aiden; Wang, Ziyu; Kianinia, Mehran; Green, Ben; Gao, Wei-bo; Aharonovich, Igor

2018-03-01

Optical properties of color centers in diamond have been the subject of intense research due to their promising applications in quantum photonics. In this work we study the optical properties of Xe related color centers implanted into nitrogen rich (type IIA) and an ultrapure, electronic grade diamond. The Xe defect has two zero phonon lines at ∼794 nm and 811 nm, which can be effectively excited using both green and red excitation, however, its emission in the nitrogen rich diamond is brighter. Near resonant excitation is performed at cryogenic temperatures and luminescence is probed under strong magnetic field. Our results are important towards the understanding of the Xe related defect and other near infrared color centers in diamond.

Damage evolution in Xe-ion irradiated rutile (TiO2) single crystals

International Nuclear Information System (INIS)

Li, F.; Sickafus, K.E.; Evans, C.R.; Nastasi, M.

1999-01-01

Rutile (TiO 2 ) single crystals with (110) orientation were irradiated with 360 keV Xe 2+ ions at 300 K to fluences ranging from 2 x 10 19 to 1 x 10 20 Xe/m 2 . Irradiated samples were analyzed using: (1) Rutherford backscattering spectroscopy combined with ion channeling analysis (RBS/C); and (2) cross-sectional transmission electron microscopy (XTEM). Upon irradiation to a fluence of 2 x 10 19 Xe/m 2 , the sample thickness penetrated by the implanted ions was observed to consist of three distinct layers: (1) a defect-free layer at the surface (thickness about 12 nm) exhibiting good crystallinity; (2) a second layer with a low density of relatively large-sized defects; and (3) a third layer consisting of a high concentration of small defects. After the fluence was increased to 7 x 10 19 Xe/m 2 , a buried amorphous layer was visible by XTEM. The thickness of the amorphous layer was found to increase with increasing Xe ion fluence. The location of this buried amorphous layer was found to coincide with the measured peak in the Xe concentration (measured by RBS/C), rather than with the theoretical maximum in the displacement damage profile. This observation suggests the implanted Xe ions may serve as nucleation sites for the amorphization transformation. The total thickness of the damaged microstructure due to ion irradiation was always found to be much greater than the projected range of the Xe ions. This is likely due to point defect migration under the high stresses induced by ion implantation

Metastable states in magnetic nanorings

DEFF Research Database (Denmark)

Castaño, F. J.; Ross, C. A.; Frandsen, Cathrine

2003-01-01

Magnetization states and hysteresis behavior of small ferromagnetic rings, of diameters 180-520 nm, have been investigated using magnetic force microscopy. In addition to the expected bi-domain ("onion") and flux-closed ("vortex") magnetization states, a metastable state has been found. This "twi......Magnetization states and hysteresis behavior of small ferromagnetic rings, of diameters 180-520 nm, have been investigated using magnetic force microscopy. In addition to the expected bi-domain ("onion") and flux-closed ("vortex") magnetization states, a metastable state has been found....... This "twisted" state contains a 360degrees domain wall which can exist over a wide range of applied fields. Four possible configurations of the twisted state are possible. Micromagnetic modeling shows that the twisted state is stabilised in small diameter, narrow rings. Additionally, more complex configurations...

Analysis of XeC1 Emission in a Hollow Cathode Discharge.

Science.gov (United States)

1981-06-01

excited homopolar molecule, e.g., Xe2 , Hg2 The term exciplex refers to an electronically excited heteropolar complex, e.g., KrF , XeOH , XeCl , which...frequently overlooked and both homopolar and heteropolar systems are commonly referred to as excimers, Excimers are formed by the interaction between two...mode and a non-scanning mode. Scanning is performed using a 1 rpm motor and produces plots of in- tensity versus wavelength. The non-scanning mode is

Effect of high Xe-concentration in a plasma display panel with a SrCaO cold cathode

International Nuclear Information System (INIS)

Uchida, Giichiro; Kajiyama, Hiroshi; Shinoda, Tsutae; Uchida, Satoshi; Akiyama, Toshiyuki

2010-01-01

We present here measurements of high Xe-contents plasma display panel (PDP) with SrCaO cold cathode. Luminous efficacy (η) shows a two-step increase with Xe-concentration in Ne/Xe gas mixture: η drastically increases up to Xe-concentration of 30% (Xe: 30%), and then attains 5 lm/W at the highest Xe-concentration of Xe: 100%. The high performance PDP with Xe: 100% can be operated at low applied voltage between 230 and 377 V due to the high secondary electron emission from the SrCaO cathode. Emission measurements clearly show the change in discharge characteristics at Xe: 30%, where the discharge changes from a Ne/Xe mixture discharge to an almost pure Xe discharge, and the vacuum ultraviolet (VUV) radiation from the combination of resonance and excimer radiations to only excimer radiation. Theoretical analysis solving Boltzmann equation for electron demonstrates that increasing Xe-concentration enhances the collision frequency for electron impact excitation directly from ground state to lower levels concerned with the VUV radiation, resulting in a drastic increase in luminous efficacy up to Xe: 30%. Also, one-dimensional fluid simulation of a Ne/Xe dielectric barrier discharge clearly shows that a combination of high secondary electron emission cathode and high Xe-concentration is quite effective for high VUV radiation efficiency because it induces a drastic increase in electron-heating efficiency.

Nuclear Structure of 124Xe Studied with β+/EC-Decay

Science.gov (United States)

Radich, A. J.; Garrett, P. E.; Allmond, J. M.; Andreoiu, C.; Ball, G. C.; Bianco, L.; Bildstein, V.; Chagnon-Lessard, S.; Cross, D. S.; Diaz Varela, A.; Dunlop, R.; Finlay, P.; Garnsworthy, A. B.; Hackman, G.; Hadinia, B.; Jigmeddorj, B.; Laffoley, A. T.; Leach, K. G.; Michetti-Wilson, J.; Orce, J. N.; Rajabali, M. M.; Rand, E.; Starosta, K.; Sumithrarachchi, C. S.; Svensson, C. E.; Triambak, S.; Wang, Z. M.; Wood, J. L.; Wong, J.; Williams, S. J.; Yates, S. W.

The nuclear structure of 124Xe was investigated using γ-ray spectroscopy following the β+/EC-decay of 124Cs. A very high-statistics data set was collected and γγ coincidence data was analyzed, greatly adding to the 124Xe level scheme. A new decay branch from the high-spin isomer of 124Cs was observed as well as weak E2 transitions into excited 0+ states in 124Xe. B(E2) transition strengths of such low-spin transitions are very important in determining collective properties, which are currently poorly characterized in the region of neutron-deficient xenon isotopes.

Role of carbon atoms in the remote plasma deposition of hydrogenated amorphous carbon

International Nuclear Information System (INIS)

Benedikt, J.; Wisse, M.; Woen, R.V.; Engeln, R.; Sanden, M.C.M. van de

2003-01-01

The aim of this article is to determine the role of carbon atoms in the growth of hydrogenated amorphous carbon (a-C:H) films by means of an argon/acetylene expanding thermal plasma. Cavity ring down absorption spectroscopy is used to detect metastable carbon atoms by probing the 1s 2 2s 2 2p 3s 1 P 1 2 2s 2 2p 2 1 S 0 electronic transition. In addition to absorption measurements, the emission of the same transition is monitored by means of optical emission spectroscopy. These two measurements provide information about the local production of the C atoms and about their reactivity in the gas phase. It will be shown that under growth conditions in an Ar/C 2 H 2 expanding thermal plasma, the metastable carbon density is also representative for the ground state carbon density. From obtained results it is concluded that the carbon atoms react rapidly with acetylene in the gas phase and therefore their contribution to the growth of hard diamond-like a-C:H films can be neglected. Only at low acetylene flows, the condition when soft polymer-like films are deposited, carbon atoms are detected close to the substrate and can possibly contribute to the film growth

High Cycle Fatigue of Metastable Austenitic Stainless Steels

OpenAIRE

Fargas Ribas, Gemma; Zapata Dederle, Ana Cristina; Anglada Gomila, Marcos Juan; Mateo García, Antonio Manuel

2009-01-01

Metastable austenitic stainless steels are currently used in applications where severe forming operations are required, such as automotive bodies, due to its excellent ductility. They are also gaining interest for its combination of high strength and formability after forming. The biggest disadvantage is the difficulty to predict the mechanical response, which depends heavily on the amount of martensite formed. The martensitic transformation in metastable stainless steels can b...

Modeling of metastable phase formation diagrams for sputtered thin films.

Science.gov (United States)

Chang, Keke; Music, Denis; To Baben, Moritz; Lange, Dennis; Bolvardi, Hamid; Schneider, Jochen M

2016-01-01

A method to model the metastable phase formation in the Cu-W system based on the critical surface diffusion distance has been developed. The driver for the formation of a second phase is the critical diffusion distance which is dependent on the solubility of W in Cu and on the solubility of Cu in W. Based on comparative theoretical and experimental data, we can describe the relationship between the solubilities and the critical diffusion distances in order to model the metastable phase formation. Metastable phase formation diagrams for Cu-W and Cu-V thin films are predicted and validated by combinatorial magnetron sputtering experiments. The correlative experimental and theoretical research strategy adopted here enables us to efficiently describe the relationship between the solubilities and the critical diffusion distances in order to model the metastable phase formation during magnetron sputtering.

Electronic and atomic impacts on large clusters

International Nuclear Information System (INIS)

Gspann, J.

1982-01-01

Describing first the generation and properties of molecular beams of large Van der Waals clusters such as speed distribution, cluster size distribution, and internal temperature of the clusters, the review then features the results of electronic impacts on large clusters: metastable electronic cluster excitations, ejection of positive cluster ions of less than 100 atoms from much larger parent clusters, and ionization of the large clusters. Atomic impacts at thermal energies are treated with respect to the scattering cross section of the clusters, their drag coefficient in free molecular flow, and the peculiarities of impacts on helium clusters of either isotope. (Auth.)

Radiation-sustained nanocluster metastability in oxide dispersion strengthened materials

Science.gov (United States)

Ribis, J.; Bordas, E.; Trocellier, P.; Serruys, Y.; de Carlan, Y.; Legris, A.

2015-12-01

ODS materials constitute a new promising class of structural materials for advanced fission and fusion energy application. These Fe-Cr based ferritic steels contain ultra-high density of dispersion-strengthening nanoclusters conferring excellent mechanical properties to the alloy. Hence, guarantee the nanocluster stability under irradiation remain a critical issue. Nanoclusters are non-equilibrium multicomponent compounds (YTiCrO) forming through a complex nucleation pathway during the elaboration process. In this paper, it is proposed to observe the response of these nanoclusters when the system is placed far from equilibrium by means of ion beam. The results indicate that the Y, Ti, O and Cr atoms self-organized so that nanoclusters coarsened but maintain their non-equilibrium chemical composition. It is discussed that the radiation-sustained nanocluster metastability emerges from cooperative effects: radiation-induced Ostwald ripening, permanent creation of vacancies in the clusters, and fast Cr diffusion mediated by interstitials.

Radiation-sustained nanocluster metastability in oxide dispersion strengthened materials

International Nuclear Information System (INIS)

Ribis, J.; Bordas, E.; Trocellier, P.; Serruys, Y.; Carlan, Y. de; Legris, A.

2015-01-01

ODS materials constitute a new promising class of structural materials for advanced fission and fusion energy application. These Fe–Cr based ferritic steels contain ultra-high density of dispersion-strengthening nanoclusters conferring excellent mechanical properties to the alloy. Hence, guarantee the nanocluster stability under irradiation remain a critical issue. Nanoclusters are non-equilibrium multicomponent compounds (YTiCrO) forming through a complex nucleation pathway during the elaboration process. In this paper, it is proposed to observe the response of these nanoclusters when the system is placed far from equilibrium by means of ion beam. The results indicate that the Y, Ti, O and Cr atoms self-organized so that nanoclusters coarsened but maintain their non-equilibrium chemical composition. It is discussed that the radiation-sustained nanocluster metastability emerges from cooperative effects: radiation-induced Ostwald ripening, permanent creation of vacancies in the clusters, and fast Cr diffusion mediated by interstitials.

Tumor ocular metastásico Metastatic ocular tumor

Directory of Open Access Journals (Sweden)

Martha G Domínguez Expósito

2004-06-01

Full Text Available El carcinoma metastásico del ojo es considerado la neoplasia maligna que más frecuente se encuentra de forma intraocular. Solo cerca del 10 % de las personas que tienen una o más lesiones metastásicas intraoculares son detectadas clínicamente antes de la muerte. A menudo, el carcinoma metastásico ocular es diagnosticado por el oftalmólogo ante la presencia de síntomas oculares. Las lesiones están localizadas con preferencia en coroides. Nos motivo a realizar la presentación de este caso la presencia de lesiones intraoculares múltiples tumorales metastásicos en un paciente cuyo síntoma de presentación fue la disminución de la agudeza visualThe eye metastatic carcinoma is considered the most frequently found intraocular malignant neoplasia. Only 10 % of the persons with one or more metastatic intraocular injuries are clinically detected before death. The metastatic ocular carcinoma is often diagnosed by the ophthalmologist in the presence of ocular symptoms. The injuries are preferably located in the choroid. The appearance of multiple metastatic intraaocular tumoral injuries in a patient whose chief complaint was the reduction of visual acuity motivated us to presente this case

Effect of plasma oscillations of C60 collectivized electrons on photoionization of endohedral noble-gas atoms

International Nuclear Information System (INIS)

Amusia, M. Ya.; Baltenkov, A. S.

2006-01-01

It is demonstrated that outer and inner electron shells, including that formed by collectivized electrons of the fullerene C 60 , affects dramatically the cross section of the subvalent ns subshells of the noble-gas endohedral atoms A-C 60 . The calculations are performed within the framework of a very simple, so-called ''orange skin,'' model that makes it possible, in spite of its simplicity, to take into account the modification of the ns subshell due to its interaction with inner and outer atomic shells, as well as with the collectivized electrons of the C 60 . As a concrete example, we consider the Xe 5s electrons completely collectivized by the powerful action of the Xe close and remote multielectron neighboring shells

Multi-quantum excitation in optically pumped alkali atom: rare gas mixtures

Science.gov (United States)

Galbally-Kinney, K. L.; Rawlins, W. T.; Davis, S. J.

2014-03-01

Diode-pumped alkali laser (DPAL) technology offers a means of achieving high-energy gas laser output through optical pumping of the D-lines of Cs, Rb, and K. The exciplex effect, based on weak attractive forces between alkali atoms and polarizable rare gas atoms (Ar, Kr, Xe), provides an alternative approach via broadband excitation of exciplex precursors (XPAL). In XPAL configurations, we have observed multi-quantum excitation within the alkali manifolds which result in infrared emission lines between 1 and 4 μm. The observed excited states include the 42FJ states of both Cs and Rb, which are well above the two-photon energy of the excitation laser in each case. We have observed fluorescence from multi-quantum states for excitation wavelengths throughout the exciplex absorption bands of Cs-Ar, Cs-Kr, and Cs-Xe. The intensity scaling is roughly first-order or less in both pump power and alkali concentration, suggesting a collisional energy pooling excitation mechanism. Collisional up-pumping appears to present a parasitic loss term for optically pumped atomic systems at high intensities, however there may also be excitation of other lasing transitions at infrared wavelengths.

L-shell X-ray production of molybdenum and niobium induced by 1500–3500 keV Xe26+ ions

International Nuclear Information System (INIS)

Guo, Yipan; Yang, Zhihu; Song, Zhangyong; Xu, Qiumei; Chen, Jing; Yang, Bian

2013-01-01

L-shell X-ray production cross sections are measured for molybdenum and niobium target induced by Xe 26+ ions. The incident energy range varies from 1500 to 3500 keV. The experimental results are well reproduced by the binding-energy-modified binary encounter approximation model in the united-atom limit. In addition to target L-shell X-ray spectra, we also observe a weak spectrum which corresponds to the forbidden transition 3d → 2s from the projectiles

Test of Lorentz symmetry with a {sup 3}He/{sup 129}Xe clock-comparison experiment

Energy Technology Data Exchange (ETDEWEB)

Gemmel, Claudia

2011-01-28

The minimal Standard Model Extension (SME) of Kostelecky and coworkers, which parametrizes the general treatment of CPT- and Lorentz invariance violation, predicts sidereal modulations of atomic transition frequencies as the Earth rotates relative to a Lorentz-violating background field. One method to search for these modulations is the so-called clock-comparison experiment, where the frequencies of co-located clocks are compared as they rotate with respect to the fixed stars. In this work an experiment is presented where polarized {sup 3}He and {sup 129}Xe gas samples in a glass cell serve as clocks, whose nuclear spin precession frequencies are detected with the help of highly sensitive SQUID sensors inside a magnetically shielded room. The unique feature of this experiment is the fact that the spins are precessing freely, with transverse relaxation times T{sup *}{sub 2} of up to 4.4 h for {sup 129}Xe and 14.1 h for {sup 3}He. To be sensitive to Lorentz-violating effects, the influence of external magnetic fields is canceled via the weighted {sup 3}He/{sup 129}Xe phase difference, {delta}{phi}={phi}{sub he}-({gamma}{sub he})/({gamma}{sub xe}) {phi}{sub xe}. The Lorentz-violating SME parameters for the neutron, b{sup n}{sub X} and b{sup n}{sub Y}, are determined out of a {chi}{sup 2} fit on the phase difference data of 7 spin precession measurements of 12 to 16 hours length. The piecewise defined fit model contains a sine and a cosine term to describe the sidereal modulation, as well as 7 offset terms, 7 linear terms and 7 . 2 exponential terms decreasing with T{sup *}{sub 2,he} and T{sup *}{sub 2,xe}, which are assigned to the respective measurement. The linear term in the weighted phase difference mainly arises from deviations of the gyromagnetic ratios from their literature values due to chemical shifts, while the exponential terms reflect the phase shifts resulting from demagnetization fields in the non-ideally spherical sample cell. The result of the {chi

Hyperpolarized 129Xe MRI: A viable functional lung imaging modality?

International Nuclear Information System (INIS)

Patz, Samuel; Hersman, F. William; Muradian, Iga; Hrovat, Mirko I.; Ruset, Iulian C.; Ketel, Stephen; Jacobson, Francine; Topulos, George P.; Hatabu, Hiroto; Butler, James P.

2007-01-01

The majority of researchers investigating hyperpolarized gas MRI as a candidate functional lung imaging modality have used 3 He as their imaging agent of choice rather than 129 Xe. This preference has been predominantly due to, 3 He providing stronger signals due to higher levels of polarization and higher gyromagnetic ratio, as well as its being easily available to more researchers due to availability of polarizers (USA) or ease of gas transport (Europe). Most researchers agree, however, that hyperpolarized 129 Xe will ultimately emerge as the imaging agent of choice due to its unlimited supply in nature and its falling cost. Our recent polarizer technology delivers vast improvements in hyperpolarized 129 Xe output. Using this polarizer, we have demonstrated the unique property of xenon to measure alveolar surface area noninvasively. In this article, we describe our human protocols and their safety, and our results for the measurement of the partial pressure of pulmonary oxygen (pO 2 ) by observation of 129 Xe signal decay. We note that the measurement of pO 2 by observation of 129 Xe signal decay is more complex than that for 3 He because of an additional signal loss mechanism due to interphase diffusion of 129 Xe from alveolar gas spaces to septal tissue. This results in measurements of an equivalent pO 2 that accounts for both traditional T 1 decay from pO 2 and that from interphase diffusion. We also provide an update on new technological advancements that form the foundation for an improved compact design polarizer as well as improvements that provide another order-of-magnitude scale-up in xenon polarizer output

Direct Observation of Xe and Kr Adsorption in a Xe-Selective Microporous Metal-Organic Framework

NARCIS (Netherlands)

Chen, X.; Plonka, A.M.; Banerjee, D.; Krishna, R.; Schaef, H.T.; Ghose, S.; Thallapally, P.K.; Parise, J.B.

2015-01-01

The cryogenic separation of noble gases is energy-intensive and expensive, especially when low concentrations are involved. Metal organic frameworks (MOFs) containing polarizing groups within their pore spaces are predicted to be efficient Xe/Kr solid,state adsorbents, but no experimental insights

Magnetic dipole strength in 128Xe and 134Xe in the spin-flip resonance region

Science.gov (United States)

Massarczyk, R.; Rusev, G.; Schwengner, R.; Dönau, F.; Bhatia, C.; Gooden, M. Â. E.; Kelley, J. Â. H.; Tonchev, A. Â. P.; Tornow, W.

2014-11-01

The magnetic dipole strength in the energy region of the spin-flip resonance is investigated in 128Xe and 134Xe using quasimonoenergetic and linearly polarized γ -ray beams at the High-Intensity γ -Ray Source facility in Durham, North Carolina, USA. Absorption cross sections were deduced for the magnetic and electric and dipole strength distributions separately for various intervals of excitation energy, including the strength of states in the unresolved quasicontinuum. The magnetic dipole strength distributions show structures resembling a resonance in the spin-flip region around an excitation energy of 8 MeV. The electric dipole strength distributions obtained from the present experiments are in agreement with the ones deduced from an earlier experiment using broad-band bremsstrahlung instead of a quasimonoenergetic beam. The experimental magnetic and electric dipole strength distributions are compared with phenomenological approximations and with predictions of a quasiparticle random phase approximation in a deformed basis.

Orientation of Ar(3P2) atoms by laser optical pumping

International Nuclear Information System (INIS)

Giberson, K.W.; Hart, M.W.; Hammond, M.S.; Dunning, F.B.; Walters, G.K.

1984-01-01

A beam of argon metastable atoms with a high degree of electron-spin polarization has been produced by optical pumping using an Oxazine 750 dye laser. The beam is suitable for the study of electron spin and orbital orientation dependences in a variety of collision processes

Noble gas bond and the behaviour of XeO3 under pressure.

Science.gov (United States)

Hou, Chunju; Wang, Xianlong; Botana, Jorge; Miao, Maosheng

2017-10-18

Over the past few decades, the concept of hydrogen bonds, in which hydrogen is electrophilic, has been extended to halogen bonds, chalcogen bonds and pnicogen bonds. Herein, we show that such a non-covalent bonding also exists in noble gas compounds. Using first principles calculations, we illustrate the OXe-O bond in molecular crystal XeO 3 and its effect on the behavior of this compound under pressure. Our calculations show that the covalent Xe-O bond lengths were elongated with increasing pressure and correspondingly the Xe-O stretching vibration frequencies were red shifted, which is similar to the change of H-bonds under pressure. The OXe-O bond and related hopping of O between neighboring Xe sites also correspond to the structural changes in the XeO 3 compounds at about 2 GPa. Our study extends the concept of hydrogen bonding to include all p-block elements and show a new bonding type for Noble gas elements in which it acts as an electrophilic species.

Neutron-induced Backgrounds in 134Xe for Large-Scale Neutrinoless Double-Beta Decay Experiments

Science.gov (United States)

Moriguchi, Nina; Kidd, Mary; Tornow, Werner

2016-09-01

136Xe is used in large neutrinoless double-beta (0 νββ) decay experiments, such as KamLAND- Zen and EXO 200. Though highly purified, 136Xe still contains a significant amount of 134Xe. Recently, a new nuclear energy level was found in 134Xe. If 134Xe decays from this proposed excited state, it will emit a 2485.7 keV gamma ray. Because this energy lies near the region of interest of 136Xe νββ decay experiments (Q value 2457.8 keV), it could make a significant contribution to the background. A purified gaseous sample of 134Xe will be irradiated with neutrons of an incident energy of 4.0 MeV at Triangle Universities Nuclear Laboratory and monitored with high-purity germanium detectors. The spectra obtained from these detectors will be analyzed for the presence of the 2581 keV gamma ray. We will report on the status of this experiment. Future plans include expanding this measurement to higher initial neutron energies. Tennesse Tech University CISE Grant program.

A first-principles study of He, Xe, Kr and O incorporation in thorium carbide

Energy Technology Data Exchange (ETDEWEB)

Pérez Daroca, D., E-mail: pdaroca@tandar.cnea.gov.ar [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, Av. General Paz 1499, 1650 San Martín, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas, 1033 Buenos Aires (Argentina); Llois, A.M. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, Av. General Paz 1499, 1650 San Martín, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas, 1033 Buenos Aires (Argentina); Mosca, H.O. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica, Av. General Paz 1499, 1650 San Martín, Buenos Aires (Argentina); Instituto de Tecnología Jorge A. Sabato, UNSAM-CNEA, Av. General Paz 1499, 1650 San Martín, Buenos Aires (Argentina)

2015-05-15

Thorium-based materials are currently being investigated in relation with their potential utilization in Generation-IV reactors as nuclear fuels. Understanding the incorporation of fission products and oxygen is very important to predict the behavior of nuclear fuels. A first approach to this goal is the study of the incorporation energies and stability of these elements in the material. By means of first-principles calculations within the framework of density functional theory, we calculate the incorporation energies of He, Xe, Kr and O atoms in Th and C vacancy sites, in tetrahedral interstitials and in Schottky defects along the 〈1 1 1〉 and 〈1 0 0〉 directions. We also analyze atomic displacements, volume modifications and Bader charges. This kind of results for ThC, to the best authors’ knowledge, have not been obtained previously, neither experimentally, nor theoretically. This should deal as a starting point towards the study of the complex behavior of fission products in irradiated ThC.

Ionization dynamics of a xenon atom in super-strong laser fields

International Nuclear Information System (INIS)

Yamakawa, Koichi; Akahane, Yutaka; Fukuda, Yuji; Aoyama, Makoto; Inoue, Norihiro; Ueda, Hideki; Utsumi, Takayuki

2003-12-01

We report on detailed investigations of ionization dynamics of a xenon atom exposed to intense 800-nm pulses of 20-fs duration in the extensive intensity range from 10 13 to 10 18 W/cm 2 . Ion yields of Xe + to Xe 20+ were observed as a function of laser intensity and compared with the results from a single active electron (SAE) based Ammosov-Delone-Krainov (ADK) model. Unexpected ionization probabilities for lower charge states and also no interplay between the inner- and outer-shells by screening are inferred. Suppression of nonsequential ionization towards higher intensity and few optical cycle regimes is also proved. (author)

Sputtering of Au induced by single Xe ion impacts

International Nuclear Information System (INIS)

Birtcher, R. C.; Donnelly, S. E.

1999-01-01

Sputtering of Au thin films has been determined for Xe ions with energies between 50 and 600 keV. In-situ transmission electron microscopy was used to observe sputtered Au during deposition on a carbon foil near the specimen. Total reflection and transmission sputtering yields for a 62 nm thick Au thin film were determined by ex-situ measurement of the total amount of Au on the carbon foils. In situ observations show that individual Xe ions eject Au nanoparticles as large as 7 nm in diameter with an average diameter of approximately 3 nm. Particle emission correlates with crater formation due to single ion impacts. Nanoparticle emission contributes significantly to the total sputtering yield for Xe ions in this energy range in either reflection or transmission geometry

Photoionization dynamics of excited Ne, Ar, Kr and Xe atoms near threshold

International Nuclear Information System (INIS)

Sukhorukov, V L; Petrov, I D; Schäfer, M; Merkt, F; Ruf, M-W; Hotop, H

2012-01-01

A review of experimental and theoretical studies of the threshold photoionization of the heavier rare-gas atoms is presented, with particular emphasis on the autoionization resonances in the spectral region between the lowest two ionization thresholds 2 P 3/2 and 2 P 1/2 , accessed from the ground or excited states. Observed trends in the positions, widths and shapes of the autoionization resonances depending on the atomic number, the principal quantum number n, the orbital angular momentum quantum number ℓ and further quantum numbers specifying the fine- and hyperfine-structure levels are summarized and discussed in the light of ab initio and multichannel quantum defect theory calculations. The dependence of the photoionization spectra on the initially prepared neutral state are also discussed, including results on the photoionization cross sections and photoelectron angular distributions of polarized excited states. The effects of various approximations in the theoretical treatment of photoionization in these systems are analysed. The very large diversity of observed phenomena and the numerous anomalies in spectral structures associated with the threshold ionization of the rare-gas atoms can be described in terms of a limited set of interactions and dynamical processes. Examples are provided illustrating characteristic aspects of the photoionization, and sets of recommended parameters describing the energy-level structure and photoionization dynamics of the rare-gas atoms are presented which were extracted in a critical analysis of the very large body of experimental and theoretical data available on these systems in the literature. (topical review)

Antibody-Unfolding and Metastable-State Binding in Force Spectroscopy and Recognition Imaging

Science.gov (United States)

Kaur, Parminder; Qiang-Fu; Fuhrmann, Alexander; Ros, Robert; Kutner, Linda Obenauer; Schneeweis, Lumelle A.; Navoa, Ryman; Steger, Kirby; Xie, Lei; Yonan, Christopher; Abraham, Ralph; Grace, Michael J.; Lindsay, Stuart

2011-01-01

Force spectroscopy and recognition imaging are important techniques for characterizing and mapping molecular interactions. In both cases, an antibody is pulled away from its target in times that are much less than the normal residence time of the antibody on its target. The distribution of pulling lengths in force spectroscopy shows the development of additional peaks at high loading rates, indicating that part of the antibody frequently unfolds. This propensity to unfold is reversible, indicating that exposure to high loading rates induces a structural transition to a metastable state. Weakened interactions of the antibody in this metastable state could account for reduced specificity in recognition imaging where the loading rates are always high. The much weaker interaction between the partially unfolded antibody and target, while still specific (as shown by control experiments), results in unbinding on millisecond timescales, giving rise to rapid switching noise in the recognition images. At the lower loading rates used in force spectroscopy, we still find discrepancies between the binding kinetics determined by force spectroscopy and those determined by surface plasmon resonance—possibly a consequence of the short tethers used in recognition imaging. Recognition imaging is nonetheless a powerful tool for interpreting complex atomic force microscopy images, so long as specificity is calibrated in situ, and not inferred from equilibrium binding kinetics. PMID:21190677

Boltzmann statistical consideration on the excitation mechanism of iron atomic lines emitted from glow discharge plasmas

International Nuclear Information System (INIS)

Zhang Lei; Kashiwakura, Shunsuke; Wagatsuma, Kazuaki

2011-01-01

A Boltzmann plot for many iron atomic lines having excitation energies of 3.3–6.9 eV was investigated in glow discharge plasmas when argon or neon was employed as the plasma gas. The plot did not show a linear relationship over a wide range of the excitation energy, but showed that the emission lines having higher excitation energies largely deviated from a normal Boltzmann distribution whereas those having low excitation energies (3.3–4.3 eV) well followed it. This result would be derived from an overpopulation among the corresponding energy levels. A probable reason for this is that excitations for the high-lying excited levels would be caused predominantly through a Penning-type collision with the metastable atom of argon or neon, followed by recombination with an electron and then stepwise de-excitations which can populate the excited energy levels just below the ionization limit of iron atom. The non-thermal excitation occurred more actively in the argon plasma rather than the neon plasma, because of a difference in the number density between the argon and the neon metastables. The Boltzmann plots yields important information on the reason why lots of Fe I lines assigned to high-lying excited levels can be emitted from glow discharge plasmas. - Highlights: ► This paper shows the excitation mechanism of Fe I lines from a glow discharge plasma. ► A Boltzmann distribution is studied among iron lines of various excitation levels. ► We find an overpopulation of the high-lying energy levels from the normal distribution. ► It is caused through Penning-type collision of iron atom with argon metastable atom.

Mass spectrometric probes of metal cluster distributions and metastable ion decay

International Nuclear Information System (INIS)

Parks, E.K.; Liu, K.; Cole, S.K.; Riley, S.J.

1988-01-01

The study of metal clusters has provided both an opportunity and a challenge to the application of mass spectrometry. These days the most often-used technique for cluster generation - laser vaporization - leads to extensive distributions of cluster sizes, from one to perhaps thousands of atoms, and most studies reported to date use excimer laser ionization and time-of-flight mass spectrometry for cluster detection. Our apparatus is a simple one-stage TOF design employing Wiley-McLauren spatial focusing and a one-meter drift tube. In a second apparatus employing a pulsed valve in the cluster source, we see asymmetric broadening of niobium cluster mass peaks under multiphoton ionization conditions, indicating metastable decay of parent cluster ions. Other studies of niobium clusters have shown no such asymmetric peaks. 2 figs

Angle Performance on Optima XE

International Nuclear Information System (INIS)

David, Jonathan; Satoh, Shu

2011-01-01

Angle control on high energy implanters is important due to shrinking device dimensions, and sensitivity to channeling at high beam energies. On Optima XE, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through a series of narrow slits, and any angle adjustment is made by steering the beam with the corrector magnet. In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightly tilting the wafer platen during implant.Using a sensitive channeling condition, we were able to quantify the angle repeatability of Optima XE. By quantifying the sheet resistance sensitivity to both horizontal and vertical angle variation, the total angle variation was calculated as 0.04 deg. (1σ). Implants were run over a five week period, with all of the wafers selected from a single boule, in order to control for any crystal cut variation.

Large-angle adjustable coherent atomic beam splitter by Bragg scattering

NARCIS (Netherlands)

Koolen, A.E.A.; Jansen, G.T.; Domen, K.F.E.M.; Beijerinck, H.C.W.; Leeuwen, van K.A.H.

2002-01-01

Using a "monochromatic" (single-axial-velocity) and slow (250 m/s) beam of metastable helium atoms, we realize up to eighth-order Bragg scattering and obtain a splitting angle of 6 mrad at low laser power (3 mW). This corresponds to a truly macroscopic separation of 12 mm on the detector. For

Extended Neural Metastability in an Embodied Model of Sensorimotor Coupling

Directory of Open Access Journals (Sweden)

Miguel Aguilera

2016-09-01

Full Text Available The hypothesis that brain organization is based on mechanisms of metastable synchronization in neural assemblies has been popularized during the last decades of neuroscientific research. Nevertheless, the role of body and environment for understanding the functioning of metastable assemblies is frequently dismissed. The main goal of this paper is to investigate the contribution of sensorimotor coupling to neural and behavioural metastability using a minimal computational model of plastic neural ensembles embedded in a robotic agent in a behavioural preference task. Our hypothesis is that, under some conditions, the metastability of the system is not restricted to the brain but extends to the system composed by the interaction of brain, body and environment. We test this idea, comparing an agent in continuous interaction with its environment in a task demanding behavioural flexibility with an equivalent model from the point of view of 'internalist neuroscience'. A statistical characterization of our model and tools from information theory allows us to show how (1 the bidirectional coupling between agent and environment brings the system closer to a regime of criticality and triggers the emergence of additional metastable states which are not found in the brain in isolation but extended to the whole system of sensorimotor interaction, (2 the synaptic plasticity of the agent is fundamental to sustain open structures in the neural controller of the agent flexibly engaging and disengaging different behavioural patterns that sustain sensorimotor metastable states, and (3 these extended metastable states emerge when the agent generates an asymmetrical circular loop of causal interaction with its environment, in which the agent responds to variability of the environment at fast timescales while acting over the environment at slow timescales, suggesting the constitution of the agent as an autonomous entity actively modulating its sensorimotor coupling

Extended Neural Metastability in an Embodied Model of Sensorimotor Coupling.

Science.gov (United States)

Aguilera, Miguel; Bedia, Manuel G; Barandiaran, Xabier E

2016-01-01

The hypothesis that brain organization is based on mechanisms of metastable synchronization in neural assemblies has been popularized during the last decades of neuroscientific research. Nevertheless, the role of body and environment for understanding the functioning of metastable assemblies is frequently dismissed. The main goal of this paper is to investigate the contribution of sensorimotor coupling to neural and behavioral metastability using a minimal computational model of plastic neural ensembles embedded in a robotic agent in a behavioral preference task. Our hypothesis is that, under some conditions, the metastability of the system is not restricted to the brain but extends to the system composed by the interaction of brain, body and environment. We test this idea, comparing an agent in continuous interaction with its environment in a task demanding behavioral flexibility with an equivalent model from the point of view of "internalist neuroscience." A statistical characterization of our model and tools from information theory allow us to show how (1) the bidirectional coupling between agent and environment brings the system closer to a regime of criticality and triggers the emergence of additional metastable states which are not found in the brain in isolation but extended to the whole system of sensorimotor interaction, (2) the synaptic plasticity of the agent is fundamental to sustain open structures in the neural controller of the agent flexibly engaging and disengaging different behavioral patterns that sustain sensorimotor metastable states, and (3) these extended metastable states emerge when the agent generates an asymmetrical circular loop of causal interaction with its environment, in which the agent responds to variability of the environment at fast timescales while acting over the environment at slow timescales, suggesting the constitution of the agent as an autonomous entity actively modulating its sensorimotor coupling with the world. We

Glassy and Metastable Crystalline BaTi2O5 by Containerless Processing

Science.gov (United States)

Yoda, Shinichi; Kentei Yu, Yu; Kumar, Vijaya; Kameko, Masashi

Many efforts have been devoted to forming bulk glass from the melt of ferroelectric crystalline materials without adding any network-forming oxides such as SiO2 due to the potential for producing transparent glass ceramics with high dielectric constant and enhanced piezoelectric, pyroelectric and electro-optic use. The containerless processing is an attractive synthesis tech-nique as it can prevent melt contamination, minimize heterogeneous nucleation, and allow melt to achieve deep undercooling for forming metastable and glassy materials. We have fabricated a new ferroelectric materiel BaTi2 O5 [1] as bulk glass from melt by us-ing containerless processing and studied the phase relationship between microstructure and ferroelectric properties of BaTi2 O5 [2]. The structures of glassy and metastable crystalline BaTi2 O5 fabricated by the containerless pro-cessing were comprehensively investigated by combined X-ray and neutron diffractions, XANES analyses and computer simulations [3]. The 3-dimensional atomic structure of glassy BaTi2 O5 (g-BaTi2 O5 ), simulated by Reverse Monte Carlo (RMC) modelling on diffraction data, shows that extremely distorted TiO5 polyhedra interconnected with both corner-and edge-shared oxy-gen, formed a higher packing density structure than that of conventional silicate glass linked with only corner-sharing of SiO4 polyhedra. In addition, XANES measurement reveales that five-coordinated TiO5 polyhedra were formable in the crystallized metastable a-and b-BaTi2 O5 phases. The structure of metastable b-BaTi2 O5 was solved by ab initio calculation, and refined by Rietveld refinement as group Pnma with unit lattices a = 10.23784 ˚, b = 3.92715 ˚, c A A = 10.92757 A ˚. Our results show that the glass-forming ability enhanced by containerless pro-cessing, not by `strong glass former', fabricated new bulk oxide glasses with peculiar structures and properties. The intermediate-range structure of g-BaTi2 O5 and the crystalline structure of

Behavior of Rydberg atoms at surfaces: energy level shifts and ionization

Energy Technology Data Exchange (ETDEWEB)

Dunning, F.B. E-mail: fbd@rice.edu; Dunham, H.R.; Oubre, C.; Nordlander, P

2003-04-01

The ionization of xenon atoms excited to the extreme red and blue states in high-lying Xe(n) Stark manifolds at a metal surface is investigated. The data show that, despite their very different initial spatial characteristics, the extreme members of a given Stark manifold ionize at similar atom/surface separations. This is explained, with the aid of complex scaling calculations, in terms of the strong perturbations in the energies and structure of the atomic states induced by the presence of the surface which lead to avoided crossings between neighboring levels as the surface is approached.

Behavior of Rydberg atoms at surfaces: energy level shifts and ionization

CERN Document Server

Dunning, F B; Oubre, C D; Nordlander, P

2003-01-01

The ionization of xenon atoms excited to the extreme red and blue states in high-lying Xe(n) Stark manifolds at a metal surface is investigated. The data show that, despite their very different initial spatial characteristics, the extreme members of a given Stark manifold ionize at similar atom/surface separations. This is explained, with the aid of complex scaling calculations, in terms of the strong perturbations in the energies and structure of the atomic states induced by the presence of the surface which lead to avoided crossings between neighboring levels as the surface is approached.

Energy barriers between metastable states in first-order quantum phase transitions

Science.gov (United States)

Wald, Sascha; Timpanaro, André M.; Cormick, Cecilia; Landi, Gabriel T.

2018-02-01

A system of neutral atoms trapped in an optical lattice and dispersively coupled to the field of an optical cavity can realize a variation of the Bose-Hubbard model with infinite-range interactions. This model exhibits a first-order quantum phase transition between a Mott insulator and a charge density wave, with spontaneous symmetry breaking between even and odd sites, as was recently observed experimentally [Landig et al., Nature (London) 532, 476 (2016), 10.1038/nature17409]. In the present paper, we approach the analysis of this transition using a variational model which allows us to establish the notion of an energy barrier separating the two phases. Using a discrete WKB method, we then show that the local tunneling of atoms between adjacent sites lowers this energy barrier and hence facilitates the transition. Within our simplified description, we are thus able to augment the phase diagram of the model with information concerning the height of the barrier separating the metastable minima from the global minimum in each phase, which is an essential aspect for the understanding of the reconfiguration dynamics induced by a quench across a quantum critical point.

Laser fluorescence spectroscopy of sputtered uranium atoms

International Nuclear Information System (INIS)

Wright, R.B.; Pellin, M.J.; Gruen, D.M.; Young, C.E.

1979-01-01

Laser induced fluorescence (LIF) spectroscopy was used to study the sputtering of 99.8% 238 U metal foil when bombarded by normally incident 500 to 3000 eV Ne + , Ar + , Kr + , and O 2 + . A three-level atom model of the LIF processes is developed to interpret the observed fluorescent emission from the sputtered species. The model shows that close attention must be paid to the conditions under which the experiment is carried out as well as to the details of the collision cascade theory of sputtering. Rigorous analysis shows that when properly applied, LIF can be used to investigate the predictions of sputtering theory as regards energy distributions of sputtered particles and for the determination of sputtering yields. The possibility that thermal emission may occur during sputtering can also be tested using the proposed model. It is shown that the velocity distribution (either the number density or flux density distribution, depending upon the experimental conditions) of the sputtered particles can be determined using the LIF technique and that this information can be used to obtain a description of the basic sputtering mechanisms. These matters are discussed using the U-atom fluorescence measurements as a basis. The relative sputtering yields for various incident ions on uranium were also measured for the first time using the LIF technique. A surprisingly high fraction of the sputtered uranium atoms were found to occupy the low lying metastable energy levels of U(I). The population of the sputtered metastable atoms were found approximately to obey a Boltzman distribution with an effective temperature of 920 +- 100 0 K. 41 references

Study of high-j neutron excitations outside 136Xe

Science.gov (United States)

Talwar, R.; Kay, B. P.; Mitchell, A. J.; Adachi, S.; Entwisle, J. P.; Fujita, Y.; Gey, G.; Noji, S.; Ong, H. J.; Schiffer, J. P.; Tamii, A.

2017-09-01

The character of single-neutron excitations outside of N = 82 has been studied using nucleon transfer reactions in terms of the energy centroid of their strength as well as the fragmentation of this strength among the actual states of the nucleus. However, extending the systematic study of the N = 83 isotones to 137Xe has been challenging due to xenon being a gas at room temperature. Though several attempts have been made, a quantitative determination of the spectroscopic factors for the neutron 9/2- and 13/2+ excitations in 137Xe is still lacking. In the present work, we report on a study of the 136Xe(α,3He)137Xe reaction carried out at 100 MeV to probe the l = 5 , 9/2- and l = 6 , 13/2+ single-neutron excitations. The experimental technique and results will be presented discussing them in context of the evolution of these single-neutron excitations and the influence of the tensor interaction on the neutron single-particle states as the proton orbits are filling. This work has been supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contract Number DE-AC02-06CH11357, the Australian Research Council Discovery Project 120104176, and the UK Science and Technology Facilities.

Zeolitic Imidazolate Framework-8 (ZIF-8) Membranes for Kr/Xe Separation

Energy Technology Data Exchange (ETDEWEB)

Wu, Ting; Feng, Xuhui; Elsaidi, Sameh K.; Thallapally, Praveen K.; Carreon, Moises A.

2017-01-30

Herein, we demonstrate that a prototypical type of metal organic framework, zeolitic imidazolate framework-8 (ZIF-8), in membrane form, can effectively separate Kr/Xe gas mixtures at industrially relevant compositions. The best membranes separated Kr/Xe mixtures with average Kr permeances as high as 1.5 × 10^-8 ± 0.2 mol/m² s Pa and average separation selectivities of 14.2 ± 1.9 for molar feed compositions corresponding to Kr/Xe ratio encountered typically in air. Molecular sieving, competitive adsorption, and differences in diffusivities were identified as the prevailing separation mechanisms. These membranes potentially represent a less-energy-intensive alternative to cryogenic distillation, which is the benchmark technology used to separate this challenging gas mixture. To our best knowledge, this is the first example of any metal organic membrane composition displaying separation ability for Kr/Xe gas mixtures.

Experimental ion mobility measurements in Xe-CO2

Science.gov (United States)

Cortez, A. F. V.; Santos, M. A. G.; Veenhof, R.; Patra, R. N.; Neves, P. N. B.; Santos, F. P.; Borges, F. I. G. M.; Conde, C. A. N.

2017-06-01

Data on ion mobility is important to improve the performance of large volume gaseous detectors. In the present work the method, experimental setup and results for the ion mobility measurements in Xe-CO2 mixtures are presented. The results for this mixture show the presence of only one peak for all gas ratios of Xe-CO2, low reduced electric fields, E/N, 10-25 Td (2.4-6.1 kV·cm-1·bar-1), low pressures 6-8 Torr (8-10.6 mbar), at room temperature.

Nucleation of metastable aragonite CaCO3 in seawater.

Science.gov (United States)

Sun, Wenhao; Jayaraman, Saivenkataraman; Chen, Wei; Persson, Kristin A; Ceder, Gerbrand

2015-03-17

Predicting the conditions in which a compound adopts a metastable structure when it crystallizes out of solution is an unsolved and fundamental problem in materials synthesis, and one which, if understood and harnessed, could enable the rational design of synthesis pathways toward or away from metastable structures. Crystallization of metastable phases is particularly accessible via low-temperature solution-based routes, such as chimie douce and hydrothermal synthesis, but although the chemistry of the solution plays a crucial role in governing which polymorph forms, how it does so is poorly understood. Here, we demonstrate an ab initio technique to quantify thermodynamic parameters of surfaces and bulks in equilibrium with an aqueous environment, enabling the calculation of nucleation barriers of competing polymorphs as a function of solution chemistry, thereby predicting the solution conditions governing polymorph selection. We apply this approach to resolve the long-standing "calcite-aragonite problem"--the observation that calcium carbonate precipitates as the metastable aragonite polymorph in marine environments, rather than the stable phase calcite--which is of tremendous relevance to biomineralization, carbon sequestration, paleogeochemistry, and the vulnerability of marine life to ocean acidification. We identify a direct relationship between the calcite surface energy and solution Mg:Ca [corrected] ion concentrations, showing that the calcite nucleation barrier surpasses that of metastable aragonite in solutions with Mg:Ca ratios consistent with modern seawater, allowing aragonite to dominate the kinetics of nucleation. Our ability to quantify how solution parameters distinguish between polymorphs marks an important step toward the ab initio prediction of materials synthesis pathways in solution.

Innovative concept for a major breakthrough in atmospheric radioactive xenon detection for nuclear explosion monitoring

International Nuclear Information System (INIS)

Le Petit, G.; Cagniant, A.; Gross, P.; Achim, P.; Douysset, G.; Taffary, T.; Moulin, C.; Morelle, M.

2013-01-01

The verification regime of the comprehensive test ban treaty (CTBT) is based on a network of three different waveform technologies together with global monitoring of aerosols and noble gas in order to detect, locate and identify a nuclear weapon explosion down to 1 kt TNT equivalent. In case of a low intensity underground or underwater nuclear explosion, it appears that only radioactive gases, especially the noble gas which are difficult to contain, will allow identification of weak yield nuclear tests. Four radioactive xenon isotopes, 131m Xe, 133m Xe, 133 Xe and 135 Xe, are sufficiently produced in fission reactions and exhibit suitable half-lives and radiation emissions to be detected in atmosphere at low level far away from the release site. Four different monitoring CTBT systems, ARIX, ARSA, SAUNA, and SPALAX TM have been developed in order to sample and to measure them with high sensitivity. The latest developed by the French Atomic Energy Commission (CEA) is likely to be drastically improved in detection sensitivity (especially for the metastable isotopes) through a higher sampling rate, when equipped with a new conversion electron (CE)/X-ray coincidence spectrometer. This new spectrometer is based on two combined detectors, both exhibiting very low radioactive background: a well-type NaI(Tl) detector for photon detection surrounding a gas cell equipped with two large passivated implanted planar silicon chips for electron detection. It is characterized by a low electron energy threshold and a much better energy resolution for the CE than those usually measured with the existing CTBT equipments. Furthermore, the compact geometry of the spectrometer provides high efficiency for X-ray and for CE associated to the decay modes of the four relevant radioxenons. The paper focus on the design of this new spectrometer and presents spectroscopic performances of a prototype based on recent results achieved from both radioactive xenon standards and air sample

The atomic nucleus as a target

International Nuclear Information System (INIS)

Strugalski, Z.; Pawlak, T.

1981-01-01

The purpose of this article is to characterize the atomic nucleus used as a target in hadron-nucleus collision experiments. The atomic nucleus can be treated as a lens-shaped ''slab'' of nuclear matter. Such ''slab'' should be characterized by the nuclear matter layer thickness at any impact parameter, by its average thickness, and by its maximal thickness. Parameters characterizing atomic nuclei as targets are given for the elements: 6 12 C, 7 14 N, 8 16 O, 9 19 F, 10 20 Ne, 13 27 Al, 14 28 Si, 16 32 S, 18 40 Ar, 24 52 Cr, 26 54 Fe, 27 59 Co, 29 64 Cu, 30 65 Zn, 32 73 Ge, 35 80 Br, 47 100 Ag, 53 127 I, 54 131 Xe, 73 181 Ta, 74 184 W, 79 197 Au, 82 207 Pb, 92 -- 238 U [ru

Classification of knotted tori in 2-metastable dimension

KAUST Repository

Cencelj, Matija

2012-11-30

This paper is devoted to the classical Knotting Problem: for a given manifold N and number m describe the set of isotopy classes of embeddings N → Sm. We study the specific case of knotted tori, that is, the embeddings Sp × Sq → Sm. The classification of knotted tori up to isotopy in the metastable dimension range m > p + 3 2 q + 2, p 6 q, was given by Haefliger, Zeeman and A. Skopenkov. We consider the dimensions below the metastable range and give an explicit criterion for the finiteness of this set of isotopy classes in the 2-metastable dimension: Theorem. Assume that p+ 4 3 q +2 < mp+ 3 2 q +2 and m > 2p+q +2. Then the set of isotopy classes of smooth embeddings Sp × Sq → Sm is infinite if and only if either q + 1 or p + q + 1 is divisible by 4. © 2012 RAS(DoM) and LMS.

Classification of knotted tori in 2-metastable dimension

KAUST Repository

Cencelj, Matija; Repovš, Dušan; Skopenkov, Mikhail

2012-01-01

This paper is devoted to the classical Knotting Problem: for a given manifold N and number m describe the set of isotopy classes of embeddings N → Sm. We study the specific case of knotted tori, that is, the embeddings Sp × Sq → Sm. The classification of knotted tori up to isotopy in the metastable dimension range m > p + 3 2 q + 2, p 6 q, was given by Haefliger, Zeeman and A. Skopenkov. We consider the dimensions below the metastable range and give an explicit criterion for the finiteness of this set of isotopy classes in the 2-metastable dimension: Theorem. Assume that p+ 4 3 q +2 < mp+ 3 2 q +2 and m > 2p+q +2. Then the set of isotopy classes of smooth embeddings Sp × Sq → Sm is infinite if and only if either q + 1 or p + q + 1 is divisible by 4. © 2012 RAS(DoM) and LMS.

Repulsive wall potentials for He-(Ne,Ar,Kr,Xe) as inferred from differential cross sections

International Nuclear Information System (INIS)

Nitz, D.E.; Larson, J.; Swanson, K.; Wildgoose, C.

1993-01-01

We have obtained representations of the He-(Ne,Ar,Kr,Xe) ground state repulsive walls using model potentials optimized to fit published absolute differential cross section data for 500 and 1500 eV collisions. The HeNe potential, like the He 2 potentials can be fit using the semi-empirical HFD-B form constrained to cross zero at the proper internuclear separation. For the heavier atoms, this approach is unsuccessful and superior fits are obtained using only the purely repulsive V(r) - A EXP [-αr - βr 2 ] term of the HFD-B potential. Comparison of fitted potentials with previous results will be presented

Programming A Molecular Relay for Ultrasensitive Biodetection through ¹²⁹ Xe NMR

Energy Technology Data Exchange (ETDEWEB)

Wang, Yanfei [Department of Chemistry, University of Pennsylvania, 231 South 34th Street Philadelphia PA 19104-6323 USA; Roose, Benjamin W. [Department of Chemistry, University of Pennsylvania, 231 South 34th Street Philadelphia PA 19104-6323 USA; Philbin, John P. [Department of Chemistry, University of Pennsylvania, 231 South 34th Street Philadelphia PA 19104-6323 USA; Doman, Jordan L. [Department of Chemistry, University of Pennsylvania, 231 South 34th Street Philadelphia PA 19104-6323 USA; Dmochowski, Ivan J. [Department of Chemistry, University of Pennsylvania, 231 South 34th Street Philadelphia PA 19104-6323 USA

2015-12-21

We reported a supramolecular strategy for detecting specific proteins in complex media by using hyperpolarized ¹²⁹Xe NMR. A cucurbit[6]uril (CB[6])-based molecular relay was programmed for three sequential equilibrium conditions by designing a two-faced guest (TFG) that initially binds CB[6] and blocks the CB[6]–Xe interaction. Moreover, the protein analyte recruits the TFG and frees CB[6] for Xe binding. TFGs containing CB[6]- and carbonic anhydrase II (CAII)-binding domains were synthesized in one or two steps. X-ray crystallography confirmed TFG binding to Zn²⁺ in the deep CAII active-site cleft, which precludes simultaneous CB[6] binding. The molecular relay was reprogrammed to detect avidin by using a different TFG. Finally, Xe binding by CB[6] was detected in buffer and in E. coli cultures expressing CAII through ultrasensitive ¹²⁹Xe NMR spectroscopy.

XeCl Excimer Laser For Micro - Machining Of Materials: Preliminary Theoretical And Experimental Works.

Science.gov (United States)

Iwanejko, Leszek; Pokora, Ludwik; Stefanski, Miroslaw; Ujda, Zbigniew

1987-10-01

The paper presents the results of preliminary investigations, both theoretical and experimental, of XeC1 excimer laser pumped by transverse electric discharge with UU preionization. The medium was a mixture of gases He-Xe-HC1. A theoretical model of the XeC1 laser was worked out and a lot of laser parameters calculations were done. In the same time an excimer laser operating on the mixture He-Xe-HC1 was started, the generation of laser radiation was of energy about 20mJ.

Stark--Zeeman effect of metastable hydrogen molecules

International Nuclear Information System (INIS)

Kagann, R.H.

1975-01-01

The Stark effect of the N = 1 rotational level of orthohydrogen and the N = 2 rotational level of parahydrogen in the metastable c 3 PI/sub u/ electronic state has been measured using the molecular beam magnetic resonance method. The Stark effect of the metastable state is 10,000 times larger than that of the ground electronic state. The Stark effect of parahydrogen was found to be weakly dependent on static magnetic field strength, whereas the Stark effect of orthohydrogen was found to be more strongly dependent on the magnetic field strength. The Stark effect of orthohydrogen has been calculated using second-order perturbation theory with a pure Stark effect perturbation. The magnetic field dependence of the Stark effect was calculated using third-order perturbation theory with a mixed Stark--Zeeman effect double perturbation. A comparison of the experimental and theoretical values of α/sub perpendicular/ provides information on the electronic transition moment connecting the c 3 PI/sub u/ state to the a 3 Σ + /sub g/ state. The transition moment is needed to calculate the radiative lifetimes of the various vibrational levels of the c 3 PI/sub u/ state. The transition moment also enters the calculation of the quenching of this metastable state by an external electric field. There is a disagreement between theoretical predictions and the results of an experiment on the electric field quenching of the metastables. A test of the electronic transition moment may help shed light on this question. The experimental determination of the values of the transition moments allows one to test theory by comparing these values to those obtained by calculations employing ab initio wavefunctions

Numerical transfer-matrix study of a model with competing metastable states

DEFF Research Database (Denmark)

Fiig, T.; Gorman, B.M.; Rikvold, P.A.

1994-01-01

transition. A recently developed transfer-matrix formalism is applied to the model to obtain complex-valued ''constrained'' free-energy densities f(alpha). For particular eigenvectors of the transfer matrix, the f(alpha) exhibit finite-rangescaling behavior in agreement with the analytically continued...... 'metastable free-energy density This transfer-matrix approach gives a free-energy cost of nucleation that supports the proportionality relation for the decay rate of the metastable phase T proportional to\\Imf alpha\\, even in cases where two metastable states compete. The picture that emerges from this study...

Gain measurements of the Ca-Xe charge exchange system. [for UV lasers

Science.gov (United States)

Michels, C. J.; Chubb, D. L.

1978-01-01

Charge-exchange-pumped Ca(+) was studied for possible positive laser gain at 370.6 and 315.9 nm using an Xe MPD arc as the Xe(+) source. The present paper describes the MPD arc, the calcium injection system, the diagnostics for gain, and spontaneous emission measurements and results. No positive gain measurements were observed. A small Xe-Ca charge exchange cross section compared to He-metal laser systems charge exchange cross sections is the most probable reason why the result was negative.

New study on the XeVIII spectrum

International Nuclear Information System (INIS)

Gallardo, M.; Raineri, M.; Giuliani, M.; Lagorio, C.; Padilla, S.; Sarmiento, R.; Reyna Almandos, J.G.

2005-01-01

Capillary light sources were used to observe the spectrum of seven-times-ionized xenon, XeVIII, in the 300-6000 A wavelength range. Twenty-eight energy levels belonging to the 5s-9s, 5d-9d, 5g-9g, 7i-10i, 9l, 5p-9p, 4f-9f, 6h-9h and 8k-10k configurations were adjusted and 38 new spectral lines were classified. The XeVIII ionization energy was determined with improved accuracy using the polarization model. The analysis was supported by Hartree-Fock calculations. The weighted oscillator strengths for all the observed spectral lines were also calculated considering the fitted values for the energy parameters

New study on the XeVIII spectrum

Energy Technology Data Exchange (ETDEWEB)

Gallardo, M. [Centro de Investigaciones Opticas (CIOp) Casilla de Correo 124, 1900 La Plata (Argentina)]. E-mail: gallardom@ciop.unlp.edu.ar; Raineri, M. [Centro de Investigaciones Opticas (CIOp) Casilla de Correo 124, 1900 La Plata (Argentina)]. E-mail: monicar@ciop.unlp.edu.ar; Giuliani, M. [Dto. de Fisica, Fac. de C. Exactas y Naturales, Universidad Nacional de Mar del Plata Funes 3350 (7600) Mar del Plata (Argentina); Lagorio, C. [Dto. de Fisica, Fac. de C. Exactas y Naturales, Universidad Nacional de Mar del Plata Funes 3350 (7600) Mar del Plata (Argentina); Padilla, S. [Dto. de Fisica, Fac. de C. Exactas y Naturales, Universidad Nacional de Mar del Plata Funes 3350 (7600) Mar del Plata (Argentina); Sarmiento, R. [Dto. De Fisica, Universidad del Atlantico, A.A 1890 Barranquilla (Colombia); Reyna Almandos, J.G. [Centro de Investigaciones Opticas (CIOp) Casilla de Correo 124, 1900 La Plata (Argentina)]. E-mail: jreyna@ciop.unlp.edu.ar

2005-10-15

Capillary light sources were used to observe the spectrum of seven-times-ionized xenon, XeVIII, in the 300-6000 A wavelength range. Twenty-eight energy levels belonging to the 5s-9s, 5d-9d, 5g-9g, 7i-10i, 9l, 5p-9p, 4f-9f, 6h-9h and 8k-10k configurations were adjusted and 38 new spectral lines were classified. The XeVIII ionization energy was determined with improved accuracy using the polarization model. The analysis was supported by Hartree-Fock calculations. The weighted oscillator strengths for all the observed spectral lines were also calculated considering the fitted values for the energy parameters.

Cyclic cosmology, conformal symmetry and the metastability of the Higgs

Science.gov (United States)

Bars, Itzhak; Steinhardt, Paul J.; Turok, Neil

2013-10-01

Recent measurements at the LHC suggest that the current Higgs vacuum could be metastable with a modest barrier (height ( GeV)4) separating it from a ground state with negative vacuum density of order the Planck scale. We note that metastability is problematic for standard bang cosmology but is essential for cyclic cosmology in order to end one cycle, bounce, and begin the next. In this Letter, motivated by the approximate scaling symmetry of the standard model of particle physics and the primordial large-scale structure of the universe, we use our recent formulation of the Weyl-invariant version of the standard model coupled to gravity to track the evolution of the Higgs in a regularly bouncing cosmology. We find a band of solutions in which the Higgs field escapes from the metastable phase during each big crunch, passes through the bang into an expanding phase, and returns to the metastable vacuum, cycle after cycle after cycle. We show that, due to the effect of the Higgs, the infinitely cycling universe is geodesically complete, in contrast to inflation.

Cyclic cosmology, conformal symmetry and the metastability of the Higgs

International Nuclear Information System (INIS)

Bars, Itzhak; Steinhardt, Paul J.; Turok, Neil

2013-01-01

Recent measurements at the LHC suggest that the current Higgs vacuum could be metastable with a modest barrier (height (10 10–12 GeV) 4 ) separating it from a ground state with negative vacuum density of order the Planck scale. We note that metastability is problematic for standard bang cosmology but is essential for cyclic cosmology in order to end one cycle, bounce, and begin the next. In this Letter, motivated by the approximate scaling symmetry of the standard model of particle physics and the primordial large-scale structure of the universe, we use our recent formulation of the Weyl-invariant version of the standard model coupled to gravity to track the evolution of the Higgs in a regularly bouncing cosmology. We find a band of solutions in which the Higgs field escapes from the metastable phase during each big crunch, passes through the bang into an expanding phase, and returns to the metastable vacuum, cycle after cycle after cycle. We show that, due to the effect of the Higgs, the infinitely cycling universe is geodesically complete, in contrast to inflation

Spectroscopy of systems of two identical atoms: effects of quantum interference

International Nuclear Information System (INIS)

Makarov, A.A.; Yudson, V.I.

2017-01-01

Several effects of quantum interference in spectroscopy of a system of two atoms are discussed. (i) In the system of spatially separated atoms in a one-dimensional (1D) geometry (a single-mode waveguide or photon crystal), a (meta)stable excited entangled state can be formed, its decay being very sensitive to the distance between the atoms and to perturbations which cause a difference between their resonance frequencies. (ii) In a system of closely located atoms in 3D space, the extreme sensitivity of absorption and fluorescence spectra to the direction of the applied magnetic field is demonstrated. These theoretical predictions can be useful for the quantum information processing and ultrasensitive measurements.

Measurement of
 the azimuthal anisotropy of charged particles 
in 5.02 TeV Pb+Pb and 5.44 TeV Xe+Xe collisions 
with ATLAS

CERN Document Server

Bold, Tomasz; The ATLAS collaboration

2018-01-01

The experimental data collected by the ATLAS experiment during the 2015 Pb+Pb and 2017 Xe+Xe LHC runs offer new opportunities to study charged particle azimuthal anisotropy. The high-statistics Pb+Pb sample allows for a detailed study of the azimuthal anisotropy of produced particles. This should improve the understanding of initial conditions of nuclear collisions, hydrodynamical behavior of quark-gluon plasma and parton energy loss. New ATLAS measurements of differential and global Fourier harmonics of charged particles (vn) in 5.02 TeV Pb+Pb and 5.44 TeV Xe+Xe collisions in a wide range of transverse momenta, pseudorapidity (|η|<2.5) and collision centrality are presented. The higher order harmonics, sensitive to fluctuations in the initial state, are measured up to n=7 using the two-particle correlation, cumulant and scalar product methods. The dynamic properties of QGP are studied using a recently-proposed modified Pearson's correlation coefficient, ρ(v2n,pT), between the eventwise mean transverse m...

Laser generation of XeCl exciplex molecules in a longitudinal repetitively pulsed discharge in a Xe - CsCl mixture

Science.gov (United States)

Boichenko, A. M.; Klenovskii, M. S.

2015-12-01

By using the previously developed kinetic model, we have carried out simulations to study the possibility of laser generation of XeCl exciplex molecules in the working medium based on a mixture of Xe with CsCl vapours, excited by a longitudinal repetitively pulsed discharge. The formation mechanism of exciplex molecules in this mixture is fundamentally different from the formation mechanisms in the traditional mixtures of exciplex lasers. The conditions that make the laser generation possible are discussed. For these conditions, with allowance for available specific experimental conditions of the repetitively pulsed discharge excitation, we have obtained the calculated dependences of the power and efficiency of generation on the reflectivity of mirrors in a laser cavity.

Sequences by Metastable Attractors: Interweaving Dynamical Systems and Experimental Data

Directory of Open Access Journals (Sweden)

Axel Hutt

2017-05-01

Full Text Available Metastable attractors and heteroclinic orbits are present in the dynamics of various complex systems. Although their occurrence is well-known, their identification and modeling is a challenging task. The present work reviews briefly the literature and proposes a novel combination of their identification in experimental data and their modeling by dynamical systems. This combination applies recurrence structure analysis permitting the derivation of an optimal symbolic representation of metastable states and their dynamical transitions. To derive heteroclinic sequences of metastable attractors in various experimental conditions, the work introduces a Hausdorff clustering algorithm for symbolic dynamics. The application to brain signals (event-related potentials utilizing neural field models illustrates the methodology.

Inelastic transitions of atoms and molecules induced by van der Waals interaction with a surface

International Nuclear Information System (INIS)

Baudon, J.; Hamamda, M.; Boustimi, M.; Bocvarski, V.; Taillandier-Loize, T.; Dutier, G.; Perales, F.; Ducloy, M.

2012-01-01

Inelastic processes occuring in thermal-velocity metastable atoms and molecules passing at a mean distance (1–100 nm) are investigated. These processes are caused by the quadrupolar part of the van der Waals interaction: fine-structure transitions in atoms (Ar ∗ , Kr ∗ ), rovibrational transitions in N 2 ∗ ( 3 Σ u + ), transitions among magnetic sub-levels in the presence of a magnetic field.

Laser Cooling without Repumping: A Magneto-Optical Trap for Erbium Atoms

International Nuclear Information System (INIS)

McClelland, J.J.; Hanssen, J.L.

2006-01-01

We report on a novel mechanism that allows for strong laser cooling of atoms that do not have a closed cycling transition. This mechanism is observed in a magneto-optical trap (MOT) for erbium, an atom with a very complex energy level structure with multiple pathways for optical-pumping losses. We observe surprisingly high trap populations of over 10 6 atoms and densities of over 10 11 atoms cm -3 , despite the many potential loss channels. A model based on recycling of metastable and ground state atoms held in the quadrupole magnetic field of the trap explains the high trap population, and agrees well with time-dependent measurements of MOT fluorescence. The demonstration of trapping of a rare-earth atom such as erbium opens a wide range of new possibilities for practical applications and fundamental studies with cold atoms

Boltzmann statistical consideration on the excitation mechanism of iron atomic lines emitted from glow discharge plasmas

Energy Technology Data Exchange (ETDEWEB)

Zhang Lei; Kashiwakura, Shunsuke; Wagatsuma, Kazuaki, E-mail: wagatuma@imr.tohoku.ac.jp

2011-11-15

A Boltzmann plot for many iron atomic lines having excitation energies of 3.3-6.9 eV was investigated in glow discharge plasmas when argon or neon was employed as the plasma gas. The plot did not show a linear relationship over a wide range of the excitation energy, but showed that the emission lines having higher excitation energies largely deviated from a normal Boltzmann distribution whereas those having low excitation energies (3.3-4.3 eV) well followed it. This result would be derived from an overpopulation among the corresponding energy levels. A probable reason for this is that excitations for the high-lying excited levels would be caused predominantly through a Penning-type collision with the metastable atom of argon or neon, followed by recombination with an electron and then stepwise de-excitations which can populate the excited energy levels just below the ionization limit of iron atom. The non-thermal excitation occurred more actively in the argon plasma rather than the neon plasma, because of a difference in the number density between the argon and the neon metastables. The Boltzmann plots yields important information on the reason why lots of Fe I lines assigned to high-lying excited levels can be emitted from glow discharge plasmas. - Highlights: Black-Right-Pointing-Pointer This paper shows the excitation mechanism of Fe I lines from a glow discharge plasma. Black-Right-Pointing-Pointer A Boltzmann distribution is studied among iron lines of various excitation levels. Black-Right-Pointing-Pointer We find an overpopulation of the high-lying energy levels from the normal distribution. Black-Right-Pointing-Pointer It is caused through Penning-type collision of iron atom with argon metastable atom.

Nuclear dynamics in the metastable phase of the solid acid caesium hydrogen sulfate.

Science.gov (United States)

Krzystyniak, Maciej; Drużbicki, Kacper; Fernandez-Alonso, Felix

2015-12-14

High-resolution spectroscopic measurements using thermal and epithermal neutrons and first-principles calculations within the framework of density-functional theory are used to investigate the nuclear dynamics of light and heavy species in the metastable phase of caesium hydrogen sulfate. Within the generalised-gradient approximation, extensive calculations show that both 'standard' and 'hard' formulations of the Perdew-Burke-Ernzerhof functional supplemented by Tkatchenko-Scheffler dispersion corrections provide an excellent description of the known structure, underlying vibrational density of states, and nuclear momentum distributions measured at 10 and 300 K. Encouraged by the agreement between experiment and computational predictions, we provide a quantitative appraisal of the quantum contributions to nuclear motions in this solid acid. From this analysis, we find that only the heavier caesium atoms reach the classical limit at room temperature. Contrary to naïve expectation, sulfur exhibits a more pronounced quantum character relative to classical predictions than the lighter oxygen atom. We interpret this hitherto unexplored nuclear quantum effect as arising from the tighter binding environment of this species in this technologically relevant material.

Magnetic dipole strength in {sup 128}Xe and {sup 134}Xe in the spin-flip resonance region

Energy Technology Data Exchange (ETDEWEB)

Massarczyk, R. [Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden (Germany); Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Rusev, G. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Schwengner, R.; Doenau, F. [Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden (Germany); Bathia, C. [McMaster University, Hamilton, Ontario L8S4L8 (Canada); Gooden, M.E.; Kelley, J.H. [Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); North Carolina State University, Raleigh, NC 27695 (United States); Tonchev, A.P. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Tornow, W. [Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Duke University, Durham, NC 27708 (United States)

2015-07-01

The magnetic dipole strength in the energy region of the spin-flip resonance is investigated in {sup 128}Xe and {sup 134}Xe using quasimonoenergetic and linearly polarized γ-ray beams at the High-Intensity γ-Ray Source facility in Durham, North Carolina, USA. Absorption cross sections were deduced for the magnetic and electric and dipole strength distributions separately for various intervals of excitation energy, including the strength of states in the unresolved quasicontinuum. The magnetic dipole strength distributions show structures resembling a resonance in the spin-flip region around an excitation energy of 8 MeV. The electric dipole strength distributions obtained from the present experiments are in agreement with the ones deduced from an earlier experiment using broad-band bremsstrahlung instead of a quasimonoenergetic beam. The experimental magnetic and electric dipole strength distributions are compared with model predictions.

Theoretical search for optimal pump parameters for observing spontaneous radiation amplification on the λ=41.8-nm transition of Xe IX in plasma

International Nuclear Information System (INIS)

Ivanova, E P; Ivanov, Arkadii L

2004-01-01

Based on a collisional-radiative model, an atomic-kinetic calculation of the gains on the 41.8-nm transitions of Pd-like xenon was performed for the plasma produced due to the interaction of a femtosecond laser pulse with gaseous xenon. The gains g(z,τ) averaged over the spatial and temporal coordinates were compared with the known gains which had been measured experimentally in Xe 8+ . The amplification was shown to occur under the conditions of ionisation of the working ions, and the time of output radiation saturation depends on the time of Xe 8+ transformation to higher-ionised ions. Our theoretical investigation enables determining the optimal pump parameters, at which the product of the gain g by the active medium length L is about 20, which exceeds the experimental gL value. (active media)

Analysis and evaluation of atom level composition variation and property change due to materials irradiation damage

International Nuclear Information System (INIS)

Furuya, Kazuo; Takeguchi, Masaki; Mitsuishi, Kazuki; Song Menhi; Saito, Tetsuya

2000-01-01

This study aims at general elucidation of atom level composition variation due to radiation damage and property change accompanied with this under intending to stressing application of the in-situ analysis and evaluation apparatus on material radiation damage. Then, by using the electron energy loss spectroscopy (EELS) capable of showing a power in composition analysis at microscopic region, measurement of EELS on crystal structure change after heat treatment of Xe precipitation was carried out under parallel of its high resolution observation. As a result, a precipitation with less than 30 nm in diameter was observed on a specimen inserted at 473 K. Xe precipitates in crystalline state began to change at 623 K, to be perfectly gassy state at 773 K. In an energy filter image (EFI) using low loss of Xe, distribution of crystalline and non-crystalline Xe was observed. In EELS, peaks at 14.6 and 15.3 eV were observed in 300 and 773 K, respectively, which were thought to be plasmon. And, difference of peak position at the core loss was thought to reflex difference of Xe state at 300 and 773 K. (G.K.)

Negative heat capacities in central Xe+Sn reactions

International Nuclear Information System (INIS)

Le Neindre, N.; Bougault, R.; Gulminelli, F.

2000-02-01

In this study the fluctuation method is applied to the 32-50 A.MeV Xe + Sn central collisions detected with the INDRA multidetector. This method based on kinetic energy fluctuations allows the authors to provide information on the liquid gas phase transition in nuclear multifragmentation. In the case of Xe + Sn central reactions a divergence in the total heat capacity is observed. This divergence corresponds to large fluctuations on the detected fragment partitions. A negative heat capacity branch is measured and so tends to confirm the observation of a first order phase transition in heavy-ion collisions. (A.C.)

Comparison of 133Xe gas dynamic SPECT and thin-section CT in patients with pulmonary emphysema

International Nuclear Information System (INIS)

Takahashi, Kazue; Satoh, Katashi; Ohkawa, Motoomi

2001-01-01

We assessed 133 Xe gas dynamic single photon emission computed tomography (SPECT) by comparing washout axial images with thin-section CT (TSCT) in patients with pulmonary emphysema. Twenty-three patients were studied. All patients were diagnosed as having pulmonary emphysema on the basis of TSCT. We compared TSCT of upper, middle and lower lung fields with 133 Xe gas dynamic SPECT axial images at the corresponding levels during the 3 to 4 minutes of washout phase. If the degree of 133 Xe gas retention or TSCT finding of ventral and dorsal parts was not the same, the images were divided into two parts. A total of 174 lesions in 23 cases were examined, but 3 lesions having no retention of 133 Xe gas at equilibrium phase were excluded. The results showed that: there were 37 lesions (21.6%) with equivalent severity on both images; there were 42 lesions (24.5%) with more severity on 133 Xe gas dynamic SPECT than on TSCT; and there were 92 lesions (53.8%) with more severity on TSCT than on 133 Xe gas dynamic SPECT. The severity on 133 Xe gas dynamic SPECT and TSCT was not always compatible. One of the reasons for the variable 133 Xe gas retention even when the lesion had the same severity on TSCT, may be bronchial stricture which cannot be seen on TSCT. By comparison of axial images of 133 Xe gas dynamic SPECT with CT images, we could recognize the areas of 133 Xe gas retention in detail. Results suggest that 133 Xe gas dynamic SPECT can be useful to identify ventilation impairment in pulmonary emphysema. (author)

Level structure in 123Xe

International Nuclear Information System (INIS)

Luukko, A.; Hattula, J.; Helppi, H.; Knuuttila, O.

1980-09-01

The level structure of 123 Xe has been studied with 122 Te( 3 He,2n) and 123 Te( 3 He,3n) reactions using in-beam γ-ray spectroscopic methods. Band-like level structures based on the unique-parity hsub(11/2) neutron state and different low-j states are observed. The isomeric state proposed earlier is established at 185.4 keV with a half-life of 5.6+-0.3 μs, and a new spin assignment of 7/2 - is proposed for this level. A triaxial-rotor-model calculation has been performed to interprete the negative-parity level system. Because of the 7/2 - state, we do not obtain a consistent description of the negative-parity states with the triaxial rotor model, unlike the heavier odd-A Xe nuclei. On the other hand, the positive-parity level structures are interpreted in terms of the core-quasiparticle model supposing a vibrational core. This indicates different core shapes for the positive- and negative-parity level systems. (author)

Structure of intruder band in "1"1"9"-"1"2"9Xe

International Nuclear Information System (INIS)

Sharma, H.P.; Chakraborty, S.; Tiwary, S.S.

2017-01-01

Xe isotopes in A∼130 mass region are known for their variety of structural phenomena, such as, unexpected signature splitting, signature inversion, γ-vibration etc. These phenomena are associated to axialy asymmetric shape. The triaxial shape in Xe nuclei are expected to originate due to the availability of prolate driving low-Ω πh_1_1_/_2 orbital and oblate driving high-Ω νh11/2 orbital near Fermi surface. The observed experimental E (4"+)/E (2"+) value (∼2.5) also support the γ-soft nature of these nuclei. Interestingly, both proton and neutron alignments have been observed in νh_1_1_/_2 band in "1"1"9"-"1"2"5Xe and neutron alignment dominates. In "1"2"9Xe, proton alignment reported to dominate. It is also supported by TPRM calculations, although, there are no significant change in the neutron orbitals. Whether this change in the alignment is occurred at N=75 or 73 is not known. Therefore, it is interesting to understand the status of the neutron and proton alignment in "1"2"7Xe, which are not studied well. Hence, in-beam γ-ray spectroscopy of "1"2"7Xe was carried out using "1"2"2Sn("9Be, 4nγ) fusion-evaporation reaction at 48 MeV using INGA facility at Inter-University Accelerator Centre, New Delhi. Details of the analysis and results will be discussed during the conference. (author)

Efficiency of ablative plasma energy transfer into a massive aluminum target using different atomic number ablators

Czech Academy of Sciences Publication Activity Database

Kasperczuk, A.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Stepniewski, W.; Jach, K.; Swierczynski, R.; Renner, Oldřich; Šmíd, Michal; Ullschmied, Jiří; Cikhart, J.; Klír, D.; Kubeš, P.; Řezáč, K.; Krouský, Eduard; Pfeifer, Miroslav; Skála, Jiří

2015-01-01

Roč. 33, č. 3 (2015), s. 379-386 ISSN 0263-0346 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk(CZ) LD14089 EU Projects: European Commission(XE) 284464 - LASERLAB-EUROPE Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; AVČR(CZ) M100101208 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : ablator atomic number * crater volume * laser energy transfer * plasma ablative pressure Subject RIV: BL - Plasma and Gas Discharge Physics; BH - Optics, Masers, Lasers (UFP-V) Impact factor: 1.649, year: 2015

Theoretical Study of the NMR Chemical Shift of Xe in Supercritical Condition

DEFF Research Database (Denmark)

Lacerda Junior, Evanildo Gomes; Sauer, Stephan P. A.; Mikkelsen, Kurt Valentin

2018-01-01

In this work we investigate the level of theory necessary for reproducing the non-linear variation of the 129Xe nuclear magnetic resonance (NMR) chemical shift with the density of Xe in supercritical conditions. In detail we study how the 129Xe chemical shift depends under these conditions...... on electron correlation, relativistic and many-body effects. The latter are included using a sequential-QM/MM methodology, in which a classical MD simulation is performed first and the chemical shift is then obtained as an average of quantum calculations of 250 MD snapshots conformations carried out for Xen...... this approach we obtain very good agreement with the experimental data, showing that the chemical shift of 129Xe in supercritical conditions is very well described by cluster calculations at the HF level, with small contributions from relativistic and electron correlation effects....

Study of elementary transfer mechanisms during a collision between a swift multi-charged heavy ion and a neutral atom; Etude des mecanismes elementaires de transfert d`energie au cours d`une collision entre un ion lourd rapide multi-charge et un atome neutre

Energy Technology Data Exchange (ETDEWEB)

Jardin, P. [Caen Univ., 14 (France)

1995-12-31

This work is dedicated to the study of the energy transfer mechanisms which occur during a collision between a swift multicharged heavy ion and a neutral atom. The elementary energy energy transfer mechanisms (scattering, excitation, ionization, capture) and their consequences on the target velocity after the collision (recoil velocity) are recalled in the first chapter. In the case of small projectile diffusion angles, we show that the recoil velocity component, transverse to the incident projectile direction, results principally from the diffusion mechanism, while the longitudinal component is due essentially to the mass transfer and the inelastic energy transfer mechanisms. Since the target recoil velocities are very small, we have built an experimental set-up which reduces the impreciseness on their measurement due to the target thermal spread using, as targets, cooled atoms of a supersonic jet (temperature < 1 K). The association of time of flight and localisation techniques allows us, for each ionised target atom, to determine the three recoil velocity components with a very good accuracy (a few tens of meters per second). In chapter three, we describe the data analysis method. And then we present in the last chapter the results we have obtained for the collision systems Xe{sup 44+}(6.7 MeV/A) + Ar => Xe{sup 44} + Ar{sup q+}+qe{sup -} (q ranging from 1 to 7); Xe{sup 44+} (6.7 MeV/A) + He => Xe{sup 44+} He{sup 1+,2+}+1e{sup -},2e{sup -}. We show that it is possible to interpret the recoil velocity in terms of kinetic energy transferred to the target and to the electrons ejected from the target. (author) 44 refs.

Nuclear-driven flashlamp pumping of the atomic iodine laser

International Nuclear Information System (INIS)

Miley, G.H.

1992-03-01

This report is a study of the atomic iodine laser pumped with nuclear- excited XeBr fluorescence. Preliminary experiments, conducted in the TRIGA reactor investigated the fluorescence of the excimer XeBr under nuclear pumping with 10 B and 3 He, for use as a flashlamp gas to stimulate the laser. These measurements included a determination of the fluorescence efficiency (light emitted in the wavelength region of interest, divided by energy deposited in the gas) of XeBr under nuclear pumping, with varying excimer mixtures. Maximum fluorescence efficiencies were approximately 1%. In order to better understand XeBr under nuclear excitation, a kinetics model of the system was prepared. The model generated the time-dependant concentrations of 20 reaction species for three pulse sizes, a TRIGA pulse, a fast burst reactor pulse, and an e-beam pulse. The modeling results predicted fluorescence efficiencies significantly higher (peak efficiencies of approximately 10%) than recorded in the fluorescence experiments. The cause of this discrepancy was not fully determined. A ray tracing computer model was also prepared to evaluate the efficiency with which nuclear-induced fluorescence generated in one cavity of a laser could be coupled into another cavity containing an iodine lasant. Finally, an experimental laser cell was constructed to verify that nuclear-induced XeBr fluorescence could be used to stimulate a laser. Lasing was achieved at 1.31 micron in the TRIGA using C 3 F 7 I, a common iodine lasant. Peak laser powers were approximately 20 mW. Measured flashlamp pump powers at threshold agreed well with literature values, as did lasant pressure dependency on laser operation

Targeted Molecular Imaging of Cancer Cells Using MS2-Based ¹²⁹ Xe NMR

Energy Technology Data Exchange (ETDEWEB)

Jeong, Keunhong [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Netirojjanakul, Chawita [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Munch, Henrik K. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Sun, Jinny [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Finbloom, Joel A. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Wemmer, David E. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Biosciences Division; Pines, Alexander [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Francis, Matthew B. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division

2016-07-25

Targeted, selective, and highly sensitive ¹²⁹Xe NMR nanoscale biosensors have been synthesized using a spherical MS2 viral capsid, Cryptophane A molecules, and DNA aptamers. The biosensors showed strong binding specificity toward targeted lymphoma cells (Ramos line). Hyperpolarized ¹²⁹Xe NMR signal contrast and hyper-CEST ¹²⁹Xe MRI image contrast indicated its promise as highly sensitive hyperpolarized ¹²⁹Xe NMR nanoscale biosensor for future applications in cancer detection in vivo.

Comparative studies of atomic independent-particle potentials

International Nuclear Information System (INIS)

Talman, J.D.; Ganas, P.S.; Green, A.E.S.

1979-01-01

A number of atomic properties are compared in various independent-particle models for atoms. The models studied are the Hartree-Fock method, a variationally optimized potential model, a parametrized analytic form of the same model, parametrized analytic models constructed to fit atomic energy levels, the so-called Hartree-Fock-Slater model, and the Xα model. The physical properties compared are single-particle energy levels, total energies, and dipole polarizabilities. The extent to which the virial theorem is satisfied in the different models is also considered. The atoms Be, Ne, Ar, Kr, and Xe and ions O v and Al iv hav been compared. The results show that the experimental properties can be well represented by several of the independent-particle models. Since it has been shown that the optimized potential models yield wavefunctions that are almost the same as Hartree-Fock wavefunctions, they provide a natural solution to the problem of extending the Hartree-Fock method to excited states

Amplification at λ ∼ 2.8 A on Xe(L),(2s-bar2p-bar) double-vacancy states produced by 248 nm excitation of Xe clusters in plasma channels

International Nuclear Information System (INIS)

Borisov, Alex B; Song Xiangyang; Zhang Ping; Dasgupta, Arati; Davis, Jack; Kepple, Paul C; Dai Yang; Boyer, Keith; Rhodes, Charles K

2005-01-01

Xe(L),(2s-bar2p-bar) double-vacancy states undergo strong amplification in relativistic self-trapped plasma channels on 3d → 2p transitions in the λ = 2.78-2.81 A region. The 2 P 3/2 → 2 S 1/2 component at λ ≅ 2.786 A exhibits saturated amplification demonstrated by both (1) the observation of spectral hole-burning in the spontaneous emission profile and (2) the correlated enhancement of 3p → 2s cascade transitions ( 2 S 1/2 → 2 P j ; j = 1/2, 3/2) at λ = 2.558 and λ = 2.600 A. The condition of saturation places a lower limit of ∼10 17 W cm -2 on the intensity of the x-ray beam produced by the amplification in the channel. The anomalous strength of the amplification signalled by the saturation mirrors the equivalently anomalous behaviour observed for all 3d → 2p transitions corresponding to 2p-bar) single-vacancy Xe q+ arrays (q = 31, 32, 34, 35, 36) that exhibit gain. The conspicuous absence of amplification involving states with (2p-bar) 2 double-vacancy configurations suggests the operation of a selective interaction that enhances the production of 2s-bar2p-bar states. Overall, the generation of double-vacancy states of this genre demonstrates that an excitation rate approaching ∼1 W/atom for ionic species is achievable in self-trapped plasma channels

Experimental comparison of the critical ionization velocity in atomic and molecular gases

International Nuclear Information System (INIS)

Axnaes, I.

1978-08-01

The critical ionization velocity usub(c) of Ne, Kr, Xe, Cl 2 , O 2 , CO, CO 2 , NH 3 and H 2 O is investigated experimentally in a coaxial plasma gun. Together with experimental data obtained in earlier experiments the present results make it possible to make a systematic comparison between the critical ionization velocity for atomic and molecular gases. It is found that atomic and molecular gases tend to have values of critical ionization velocity which are respectively smaller and larger than the theoretical values. The current dependence of usub(c) is found to be different for atomic and molecular gases. A number of atomic and molecular processes relevant to the experiment are discussed

Electron impact collision strengths and transition rates for extreme ultraviolet emission from Xe10+

International Nuclear Information System (INIS)

Shen Yunfeng; Gao Cheng; Zeng Jiaolong

2009-01-01

The energy levels, oscillator strengths, and electron impact collision strengths are calculated for the Xe 10+ ion using the configuration interaction scheme implemented by the Flexible Atomic Code. These data pertain to the 3917 levels belonging to the following configurations: 4s 2 4p 6 4d 8 , 4s 2 4p 6 4d 7 4f, 4s 2 4p 6 4d 7 5l (l = s, p, d, or f), 4s 2 4p 5 4d 9 , 4s 2 4p 5 4d 8 4f, 4s 2 4p 5 4d 8 5l, 4s 2 4p 6 4d 6 5s5p, 4s 2 4p 6 4d 6 5p5d. Configuration interactions among these configurations are included in the calculation. Collision strengths are obtained at 10 scattered electron energies (1-1000 eV) and are tabulated here at five representative energies of 10, 50, 100, 500, and 1000 eV. Effective collision strengths are obtained by assuming a Maxwellian electron velocity distribution at 10 temperatures ranging from 10 to 100 eV, and are tabulated at five representative temperatures of 10, 30, 50, 70 and 100 eV in this work. The whole data set should be useful for research involving extreme ultraviolet emission from Xe 10+

Cyclic cosmology, conformal symmetry and the metastability of the Higgs

Energy Technology Data Exchange (ETDEWEB)

Bars, Itzhak [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States); Steinhardt, Paul J., E-mail: steinh@princeton.edu [California Institute of Technology, Pasadena, CA 91125 (United States); Department of Physics and Princeton Center for Theoretical Physics, Princeton University, Princeton, NJ 08544 (United States); Turok, Neil [Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5 (Canada)

2013-10-07

Recent measurements at the LHC suggest that the current Higgs vacuum could be metastable with a modest barrier (height (10{sup 10–12} GeV){sup 4}) separating it from a ground state with negative vacuum density of order the Planck scale. We note that metastability is problematic for standard bang cosmology but is essential for cyclic cosmology in order to end one cycle, bounce, and begin the next. In this Letter, motivated by the approximate scaling symmetry of the standard model of particle physics and the primordial large-scale structure of the universe, we use our recent formulation of the Weyl-invariant version of the standard model coupled to gravity to track the evolution of the Higgs in a regularly bouncing cosmology. We find a band of solutions in which the Higgs field escapes from the metastable phase during each big crunch, passes through the bang into an expanding phase, and returns to the metastable vacuum, cycle after cycle after cycle. We show that, due to the effect of the Higgs, the infinitely cycling universe is geodesically complete, in contrast to inflation.

Experimental ion mobility measurements in Xe-CH4

Science.gov (United States)

Perdigoto, J. M. C.; Cortez, A. F. V.; Veenhof, R.; Neves, P. N. B.; Santos, F. P.; Borges, F. I. G. M.; Conde, C. A. N.

2017-09-01

Data on ion mobility is important to improve the performance of large volume gaseous detectors. In the present work, the method, experimental setup and results for the ion mobility measurements in Xe-CH4 mixtures are presented. The results for this mixture show the presence of two distinct groups of ions. The nature of the ions depend on the mixture ratio since they are originated by both Xe and CH4. The results here presented were obtained for low reduced electric fields, E/N, 10-25 Td (2.4-6.1 kV ṡ cm-1 ṡ bar-1), at low pressure (8 Torr) (10.6 mbar), and at room temperature.

Laser generation of XeCl exciplex molecules in a longitudinal repetitively pulsed discharge in a Xe – CsCl mixture

International Nuclear Information System (INIS)

Boichenko, A M; Klenovskii, M S

2015-01-01

By using the previously developed kinetic model, we have carried out simulations to study the possibility of laser generation of XeCl exciplex molecules in the working medium based on a mixture of Xe with CsCl vapours, excited by a longitudinal repetitively pulsed discharge. The formation mechanism of exciplex molecules in this mixture is fundamentally different from the formation mechanisms in the traditional mixtures of exciplex lasers. The conditions that make the laser generation possible are discussed. For these conditions, with allowance for available specific experimental conditions of the repetitively pulsed discharge excitation, we have obtained the calculated dependences of the power and efficiency of generation on the reflectivity of mirrors in a laser cavity. (active media)

Laser generation of XeCl exciplex molecules in a longitudinal repetitively pulsed discharge in a Xe – CsCl mixture

Energy Technology Data Exchange (ETDEWEB)